MXPA06008139A - Aromatic polyamide tubing for vehicle applications - Google Patents

Abstract

A vehicle tube (14) includes a layer of aromatic polyamide (22). In one example, an outer layer of aromatic polyamide (24) is bonded to the layer aromatic polyamide (22). In another example, the layer of aromatic polyamide (22) includes filler and modifying agents (34) and is electrically conductive. Example filler and modifying agents (34) include carbon powder, carbon nanotubes, metal fiber, heat-stabilizing agent, impact-modifying agent or mixtures thereof. In another example, the outer layer of aromatic polyamide (24) includes a corrugated outer surface portion (70) to provide flexibility to the tube (14). One example method includes extruding an aromatic polyamide barrier layer (22), extruding a second aromatic polyamide barrier layer (24) coaxially with the first aromatic polyamide layer (22), and bonding the second aromatic polyamide barrier layer (24) to the first aromatic polyamide barrier layer (22).

Description

For two-letter codes and other abbreviations, referto the "Guidance Notes on Codes and Abbreviations" appearing at the beginning-ning ofeach regular issue of the PCT Gazette.

POISON OF POA AMAMIDA AROMATIC FOR VEHICLE APPLICATIONS BACKGROUND OF THE INVENTION This invention relates generally to an aromatic polyamide pipe for use in vehicles. The vehicles use several types of tubes. The type of tube depends on the function and environment of the operation of the vehicle system. For example, rubber tubes are commonly used in vacuum braking systems, channeled from the intake manifold in the engine to the vacuum brake booster. The vacuum carried by this tube provides the power assistance for braking. The vacuum brake pipe must be able to withstand the high temperatures of the vacuum brake system and must be resistant to fuel vapors since these vapors may migrate out of the intake manifold after the engine has been shut off. The engine cooling systems of a vehicle also use rubber tubes to handle the water-glycol coolant. The rubber tubes in the engine cooling system must be able to withstand the elevated temperatures of the cooling system while in contact with the water-glycol coolant. A conventional rubber tube usually includes several layers of fiber reinforced rubber between each layer to provide strength and durability. Rubber tubes are commonly produced by extruding an inner rubber layer on a mandrel. However, they can also be produced without using the mandrels. The fiber reinforcement is braided around the outside of the inner layer and an outer rubber layer is extruded onto the fiber reinforcement. If necessary, fiber reinforcements and rubber layers can be applied additionally. The entire tube is then cured in a curing process that transforms the raw polymer material into an interlaced elastomer. A disadvantage in this process is that it is both laborious and expensive. The thermoplastic tubes are used in the fuel system and must be able to withstand the elevated temperatures associated with the fuel system while in contact with the fuel. Fuel tubes usually include thermoplastic layers made of materials such as common grade polyamide (e.g., PA12, PA66, PA612, PA6, etc.), fluoropolymer or ethylene vinyl alcohol. A disadvantage of polyamide tubes is that they may not have adequate chemical or thermal resistance for many applications in non-fuel vehicles. As a result, polyamide tubes can degrade under extreme high temperatures or prolonged exposure at elevated temperatures. Fluoropolymers generally provide better thermal resistance than polyamide and ethylene vinyl alcohol, but are more expensive and more difficult to process. Consequently, a thermoplastic tube is needed that provides all the advantages of thermoplastics along with the heat and chemical resistance of elastomers in modern vehicle systems. BRIEF DESCRIPTION OF THE INVENTION A vehicle tube includes a layer of aromatic polyamide. In one example, the tube includes a single layer of aromatic polyamide that includes a heat stabilizing additive. In another example, an aromatic polyamide layer is bonded to another thermoplastic layer. The thermoplastic layer may be a layer of aromatic polyamide or a layer of polypropylene, polyethylene, fluoropolymer or polyamide. In another example, an outer layer of aromatic polyamide is bonded to an inner layer of aromatic polyamide and the outer layer of aromatic polyamide includes a corrugated or corrugated outer surface portion to give flexibility to the tube. An example method includes extruding an aromatic polyamide barrier layer. In another example, a second aromatic polyamide barrier layer is coaxially extruded with the aromatic polyamide barrier layer and bonded to the aromatic polyamide barrier layer using an intermediate thermoplastic layer between the aromatic polyamide barrier layer and the second barrier layer of aromatic polyamide. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 schematically illustrates a vehicle that includes a tube; Figure 2 illustrates in schematic form a cross-sectional view of a first exemplary aromatic polyamide pipe; Figure 3 schematically illustrates a cross-sectional view of a second embodiment of an exemplary aromatic polyamide tube; Figure 4 illustrates in schematic form a cross-sectional view of a third embodiment of an example aromatic polyamide tube; Figure 5 illustrates in schematic form a cross-sectional view of a fourth corrugated tube of example aromatic polyamide; Figure 6 schematically illustrates a cross-sectional view of a fifth embodiment of an exemplary aromatic polyamide corrugated tube; Figure 7 schematically illustrates a cross-sectional view of a sixth embodiment of an exemplary aromatic polyamide corrugated tube; Figure 8 schematically illustrates a cross-sectional view of a seventh embodiment of an exemplary aromatic polyamide corrugated tube; and Figure 9 schematically illustrates a cross-sectional view of an eighth embodiment of an exemplary aromatic polyamide corrugated tube. DETAILED DESCRIPTION OF THE PREFERRED MODALI DAD Figure 1 illustrates a vehicle 10 including a vehicle system 12 having a tube 1 4. The vehicle system 12 can be a motor cooling system, an air conditioning system, a system Cooling of transmission oil, a fuel system or a vacuum brake system. However, it is understood that this list of vehicle systems is not exclusive and other types of vehicle systems can be used. The tube 14 operates under a variety of conditions in the vehicle system 12, which include contact with chemicals (i.e., vehicle fluids) and / or exposure to elevated temperatures. In the example shown, the main function of the tube 14 is to carry and transport a vehicle fluid in the system 12 of the vehicle, such as a fuel. In order to maintain proper function in the desired life of the tube 14, the tube 14 is chemically resistant to the fluid of the vehicle and thermally resistant to the high temperatures required of the application. Figure 2 shows a first example embodiment of the tube 14 which includes a simple layer 22. The layer 22 includes an internal surface 26 that defines a conduit 28 through which the fluid of the vehicle can be carried and transferred. The layer 22 is made of an aromatic polyamide and includes amide groups (refers to the chemical group CNOH2) and aromatic rings. At least a portion of the amide groups is attached to the aromatic rings. An aromatic ring, as used in this description, refers to a portion of a molecular structure of the aromatic polyamide that includes six carbon atoms arranged in a ring-like structure (commonly referred to as a benzene ring).

Using aromatic polyamide in tube 14 can provide the benefit of increased strength at elevated temperatures, increased resistance to chemicals and increased resistance to penetration of vehicle fluid through tube 14 compared to previously known tubes. In one example, the aromatic polyamide has at least 50% of the amide groups bound to aromatic rings. This provides a desirable balance of heat and chemical resistance. In another example, the aromatic polyamide can be expressed in terms of a repeated chemical unit, wherein the repeated chemical unit includes an amide group attached to an aromatic ring. In another example, it is used to form the tube 14 Zytel ™ HTN (High Temperature Nylon), available from DuPont ™ (Wilmington, DE). Polyphthalamide, available from Solvay ™ Engineered Polymers (Auburn Hills, MI), or available from Kuraray Polyamide 9T, can be used alternatively to form tube 14. It should be understood, however, that alternate sources of aromatic or semi-aromatic polyamide. In the example shown, the layer 22 is made of an aromatic polyamide compound and fillers or modifying agents. Loads and agents 34 example modifiers used to form the aromatic polyamide compound include carbon powder, carbon fiber, carbon nanotubes, metal fiber, heat stabilizing agents, impact modifiers, pigments and mixtures thereof. The charges and modifying agents 34 increase, for example, the electrical conductivity, strength, impact resistance, appearance, elongation and / or temperature resistance of the tube 14. In one example, the aromatic polyamide of the layer 22 includes between 0.1% by weight and 10% by weight of heat stabilizing antioxidant agent, between 1% by weight and 50% by weight of an elastomeric or thermoplastic olefin impact modifier, and between 0.01% by weight and 15% by weight of a powder or type of pigment dye. The anti-oxidant agent of heat stabilization increases the heat resistance of the aromatic polyamide during the formation of the tube 14, during the use of the tube 14, or both. The elastomeric or thermoplastic olefin impact modifier increases the resistance of the tube 14 to impacts. The powder or type of pigment dye enhances the aesthetics of the layer 22. As is known, the powder or pigment dye type is mainly added for appearance, however, the addition of the powder or dye may slightly change the electrical properties, mechanical or other of the layer 22. In an example tube 14, the charges and modifying agents 34 are used to increase the electrical properties of the layer 22, so that the electrical resistivity of the surface of the layer 22 is between approximately 103 and 108 ohms / m2. In a vehicle system 12 (Figural) that carries fuel, for example, electrical dissipation of static electricity may be a desirable aspect. The fillers and agents desirable modifiers for increasing the electrical resistivity of the tube 14 include carbon powder, carbon fiber, carbon nanotubes, metal fiber and mixtures thereof added in effective amounts to the aromatic polyamide material. The amount of fillers and modifying agents 34 is sufficient to change a characteristic of the aromatic polyamide compound as compared to the aromatic polyamide without any fillers and modifying agents. In one example, carbon black is added to the aromatic polyamide to change the electrical resistivity of the aromatic polyamide layer. Figure 3 shows a second example embodiment of the tube 14 including the layer 22 and an outer layer 24 having an internal surface 30. The outer layer 24 is joined to an external surface 32 of the layer 22. In one example, each of the layer 22 and the outer layer 24 are made of an aromatic polyamide. In another example, the outer layer 24 is made of other thermoplastic materials such as polypropylene, polyethylene, fluoropolymer and polyamide. The aromatic polyamide includes amide groups and aromatic rings, and at least a portion of the amide groups are attached to the aromatic rings, as described above. The use of aromatic polyamides for both layer 22 and outer layer 24 can provide the benefit of having two barrier layers to prevent at least a portion of the fuel from penetrating through tube 14, while previously known tubes include only a single barrier layer (a fluoropolymer, for example).

In one example, the aromatic polyamide of at least one of layer 22 and outer layer 24 has at least 50% of the amide groups attached to the aromatic rings, as described above. This can provide a desirable balance of heat and chemical resistance. In another example, layer 22 includes fillers and modifying agents 34, as described above. In other examples, the outer layer 24 also includes filler and modifying agents 34 to increase, for example, the electrical conductivity, strength, impact resistance, elongation and / or temperature resistance of the tube 14. The tube 14 it has a corresponding total thickness and each of layer 22 and outer layer 24 has a corresponding layer thickness. In one example, the thickness of the outer layer 24 is from 50% to 95% of the total thickness of the tube 14. This may provide the benefit of reducing, for example, the cost of the tube 14 where loads and agents 34 modifiers are used more costly to make electrically conductive to layer 22. Layer 22 and outer layer 24 are formed by a known co-extrusion process. One of ordinary skill in the art will recognize the skills necessary to co-extrude the aromatic polyamide layers. Figure 4 shows a third exemplary embodiment of a tube 14 including the layer 22, the outer layer 24 and an intermediate layer 48 interposed between the layer 22 and the outer layer 24. The intermediate layer 48 acts as an adhesive to bond an inner surface 32 of the outer layer 24 to the outer surface 30 of the layer 22. In one example, each of the layer 22 and the outer layer 24 is made of aromatic polyamide. The outer layer 24 can also be made of other thermoplastic materials, such as polypropylene, polyethylene, fluoropolymer and polyamide. In one example, layer 22 includes fillers and modifying agents 34, as described above. In other examples, the outer layer 24 also includes fillers and modifying agents 34 to increase, for example, the electrical conductivity, strength, impact resistance, elongation and / or temperature resistance of the tube 14. The layer 48 intermediate is made of a thermoplastic material including, for example, polyvinylidene fluoride, ethylene chlorotrifluoroethylene, ethylene tetrafluoroethylene, polyamide, modified polyamide, polyolefin, ethylene vinyl alcohol, polyester, polybutylene naphthalate, other thermoplastics or combinations thereof. In one example, the intermediate layer 48 provides dual functions of joining the layer 22 and the outer layer 24 together and acting as an additional barrier layer for the penetration of vehicle fluid through the tube 14. Figure 5 illustrates a fourth example of tube 14 that includes layer 22 and outer layer 24 in a corrugated configuration. The layer 22 and the outer layer 24 are made of aromatic polyamide, as described above. In one example, layer 22 includes loads and agents 34 modifiers, as described above. In other examples, the outer layer 24 also includes fillers and modifying agents 34 to increase, for example, the electrical conductivity, strength, impact resistance, elongation and / or temperature resistance of the tube 14. The layer 24 external includes an outer corrugated portion 68 having at least one corrugation 70 which provides flexibility to the tube 1 4. The corrugation 70 generally has a U-shape, although other shapes are possible, and includes a height 72, a length 74, a radius 73 and a thickness 78a. In this example, the ripple 70 extends through the entire thickness 78 of the tube 1 4. That is, the thickness of each of the layer 22 and the outer layer 24 are essentially constant over a length of the tube 14. Alternatively , in a fifth embodiment, the layer 22 can be used as a single layer having a thickness 78b in a similar corrugated configuration, as illustrated in Figure 6. Figure 7 illustrates a sixth example tube 14 that includes the layer 22 and the outer layer 24 in a corrugated configuration. Layer 22 and outer layer 24 are made of aromatic polyamide, as described above. In one example, layer 22 includes fillers and modifying agents 34, as described above. In other examples, the outer layer 24 also includes fillers and modifying agents 34 to increase, for example, the electrical conductivity, strength, impact resistance, elongation and / or temperature resistance of the tube 14. The layer 24 external includes an outer corrugated portion 94 having at least one corrugation 96 that provides flexibility. The corrugation 96 is generally U-shaped, although other shapes are possible, and includes a height 98, a length 100, a radius 102 and a thickness 104a. In this example, the corrugation 96 does not extend through the entire thickness 104 of the tube 14. That is, the layer 22 includes a corrugated outer surface portion 106 and a non-corrugated inner surface portion 108. Alternatively, the layer 22 can be used in a similar corrugated configuration having only the layer 22 and the corresponding thickness 104b, as illustrated in the seventh embodiment shown in Figure 8. Figure 9 illustrates an eighth example of a tube 14 which includes layer 22 and outer layer 24 attached to layer 22. Layer 22 and outer layer 24 are made of aromatic polyamide, as described above. In one example, layer 22 includes fillers and modifying agents 34, as described above. In other examples, the outer layer 24 also includes fillers and modifying agents 34 to increase, for example, the electrical conductivity, strength, impact resistance, elongation and / or temperature resistance of the tube 14. The layer 24 external includes portions 1 14 of corrugated external surface and portions 1 16 of alternating non-corrugated external surface. In the example shown, the corrugated outer surface portions 1 14 include three corrugated 1 18, however, it is understood that less corrugated 118 or additional ones may also be used. The corrugated outer surface portions 114 and the alternating non-corrugated outer surface portions 16 may provide the benefit of adapting the flexibility of the tube 14. That is, the corrugated outer surface portions 1 14 and the outer surface portions 16 Alternating corrugations can provide flexibility between that of a corrugated pipe entirely and a tube not entirely corrugated. Similar to the examples shown in Figures 6 and 8, the corrugated outer surface portions 1 14 and the alternating non-corrugated outer surface portions 1 16 can also be used in a single layer configuration. The examples of Figures 5 to 9 can provide a benefit in vehicle systems 12 (Figural) where flexibility is desirable., for example, for assembling or bending the tube 14 around an obstacle in the vehicle 10. There are several other advantages of the aromatic polyamide tube 14 of the present invention. In one, the tube provides chemical resistance, temperature and fluid penetration of the vehicle and can withstand the aggressive environment under the hood of a vehicle. The tube is also recyclable and can also be less expensive and lighter in weight than other plastic or rubber tubes. The invention has been described in an illustrative manner, and it is understood that the terminology used is intended to be in the nature of description words rather than limitation. Various modifications and variations of the examples described are possible in light of the above teachings. It is understood, therefore, that within the scope of the appended claims, the invention can be practiced in another way than specifically described.

Claims (30)

1. CLAIMS 1. A vehicle pipeline comprising: a pipe including an aromatic polyamide layer defining a conduit.
2. 2. The vehicle pipeline as mentioned in the Claim 1, which includes a second layer of a thermoplastic material bonded to the aromatic polyamide layer.
3. 3. The vehicle pipeline as recited in Claim 2, wherein the second layer of thermoplastic material includes at least one of aromatic polyamide, polypropylene, polyethylene, fluoropolymer, polyamide, and mixtures thereof.
4. The vehicle pipeline as recited in Claim 2, wherein the second layer of thermoplastic material is an outer layer having an outer layer thickness and the pipe has a total thickness and the thickness of the outer layer comprises between approximately 50% and 95% of the total thickness.
5. The vehicle pipeline as recited in Claim 2, which includes an intermediate thermoplastic layer located between the aromatic polyamide layer and the second layer of thermoplastic material.
6. The vehicle pipeline as recited in Claim 2, wherein the aromatic polyamide layer includes an outer surface and the second layer of thermoplastic material includes an inner surface and the outer surface of the second layer of thermoplastic material makes contact with the inner surface of the aromatic polyamide layer.
7. The vehicle pipeline as recited in Claim 1, wherein the aromatic polyamide of the aromatic polyamide layer includes a repeating chemical unit having an amide group and an aromatic ring and the amide group is attached to the aromatic ring.
8. The vehicle tubing as recited in Claim 1, wherein the aromatic polyamide of the aromatic polyamide layer includes amide groups and aromatic rings and at least a portion of the amide groups are attached to the aromatic rings.
9. 9. The vehicle pipeline as recited in Claim 8, wherein at least 50% of the amide groups are attached to the aromatic rings. 1 0.
10. The vehicle pipeline as mentioned in Claim 8, wherein the aromatic polyamide of the aromatic polyamide layer includes at least one of an impact modifying agent, a heat stabilizing agent, a heat stabilizing agent and a color pigment. eleven .
11. The vehicle pipeline as mentioned in the Claim 1, wherein the aromatic polyamide layer includes a conductive material having a surface electrical resistivity between about 1 02 and 1 07 ohms / square.
12. The vehicle pipeline as recited in Claim 1, wherein the conductive material includes at least one of carbon powder, carbon fiber, carbon nanotubes, metal fiber, metal powder and mixtures thereof. .
13. 13. The vehicle pipeline as recited in Claim 1, wherein the aromatic polyamide layer includes a corrugated outer surface.
14. 14. A vehicle pipeline comprising: a first layer of a first thermoplastic material including a corrugated outer surface portion; and a second layer of a second thermoplastic material bonded to the first layer, wherein at least one of the first thermoplastic material and the second thermoplastic material includes an aromatic polyamide.
15. 15. The vehicle pipeline as recited in Claim 14, wherein the second layer includes a corrugated inner portion and a corrugated outer surface portion corresponding to the outer corrugated surface portion of the first layer.
16. 16. The vehicle pipeline as recited in Claim 14, wherein the second layer includes an uncorrugated outer surface portion and a corrugated outer surface portion corresponding to the outer corrugated surface portion of the first layer.
17. 17. The vehicle pipe as recited in Claim 16, wherein the pipe includes a length, the first layer has a first wall thickness and the second layer has a second wall thickness, and one of the first wall thickness and the second wall thickness is essentially constant in the length of the pipe and the other of the first wall thickness and the second wall thickness changes with the length of the pipe.
18. 18. The vehicle pipeline as mentioned in the Claim 16, wherein the first layer includes an uncorrugated outer surface portion adjacent to the corrugated outer surface portion.
19. 19. The vehicle pipeline as recited in Claim 18, wherein the pipeline includes a length, and the length includes portions of noncorrugated outer surface and alternating corrugated outer surface portions.
20. 20. The vehicle pipeline as recited in Claim 14, wherein the first layer and the second layer both include an aromatic polyamide. twenty-one .
21. A method for resisting the penetration of a fluid through a pipe wall, comprising the steps of: extruding the aromatic polyamide into a layer of aromatic polyamide that forms a conduit.
22. The method as recited in Claim 21, which includes the steps of extruding a second layer of aromatic polyamide coaxially with the aromatic polyamide layer layer, and bonding the second layer of aromatic polyamide to the aromatic polyamide layer.
23. The method as recited in Claim 22, which includes the step of attaching the second layer of aromatic polyamide to the aromatic polyamide layer with an intermediate thermoplastic layer placed between the second layer of aromatic polyamide and the aromatic polyamide layer.
24. The method as recited in Claim 21, which includes the step of forming a corrugated outer surface in the aromatic polyamide layer.
25. The method as recited in Claim 21, which includes the step of adding at least one of carbon powder, carbon fiber, carbon nanotubes, metal fiber, metal powder, a heat stabilizing agent, an impact modifying agent and mixtures thereof to the aromatic polyamide before extruding the aromatic polyamide layer.
26. 26. A vehicle pipeline comprising: a first layer of aromatic polyamide; and a second layer of aromatic polyamide attached to the first layer of aromatic polyamide.
27. 27. The tubing as recited in Claim 26, which includes an intermediate thermoplastic layer between the first layer of aromatic polyamide and the second layer of aromatic polyamide.
28. The pipeline as recited in Claim 26, wherein at least one of the first layer of aromatic polyamide and the second layer of aromatic polyamide includes at least one of an impact modifying agent, a heat stabilizing agent. , a color pigment and mixtures thereof.
29. 29. The pipe as mentioned in claim 26, wherein the first layer of aromatic polyamide is an inner layer relative to the second layer of aromatic polyamide and the first layer of aromatic polyamide includes a conductive material and has an electrical surface resistivity between approximately 102 and 10r ohms / square.
30. 30. The pipe as set forth in claim 29, wherein the conductive material includes at least one of carbon powder, carbon fiber, carbon nanotubes, metal fiber, metal powder and mixtures thereof.