Stock material or miscellaneous articles – Hollow or container type article – Glass – ceramic – or sintered – fused – fired – or calcined metal...
Reexamination Certificate
1999-01-27
2001-09-25
Dye, Rena L. (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
Glass, ceramic, or sintered, fused, fired, or calcined metal...
C428S036400, C428S036910, C138S137000, C138S141000, C138S146000
Reexamination Certificate
active
06294234
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fluid conduit for fuels and fuel vapors (hereinafter “fuel or fuel vapor fluid conduits”). More specifically, the present invention relates to fuel or fuel vapor fluid conduits that are made of thermoplastic materials.
2. Discussion of the Related Arts
To meet the requirements of fuel or fuel vapor fluid conduits, such as, for example, high diffusion-blocking ability, flexibility, tensile strength and impact strength, conventional fluid conduits have been produced from several layers. Each layer satisfies some of these requirements. But these several layers are not compatible with each other. In other words, the layers (e.g., polyvinylidenefluoride and polyamide) must be joined to each other by bonding. Compatibility or adhesive agents are used to bond these chemically diverse materials to each other. Once the conventional fluid conduit is made, the bonded layers of material, which together form the fluid conduit, can not be used in a recycling process to produce new conduits.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a fuel or fuel vapor fluid conduit that is made from a reusable material and satisfies the requirements of these types of fluid conduits.
This and other objects are achieved, in accordance with a currently preferred exemplary embodiment of the present invention, by a fluid conduit that is made from a first thermoplastic material including a thermoplastic polyester elastomer and a second thermoplastic material including a thermoplastic polyester having a higher bending strength and flexibility and a lower tensile strength and impact strength than the first material.
The first and second thermoplastic materials, in combination, meet the essential requirements for fuel and fuel vapor conduits, such as, for example, low fuel permeation, high flexibility, tensile strength and impact strength. The fluid conduit made from the first and second thermoplastic materials is preferably hot formed, for example, by extrusion, and the materials are joined in this process by fusion. Moreover, the fluid conduit material can, after being melted down, be reused in a recycling process to produce a new fluid conduit.
The waste materials, such as, for example, clippings that are produced during the manufacturing of the fluid conduit, can also be reused.
The first and second materials can be mixed together. A fluid conduit formed from the mixed materials still meets the essential requirements of fuel or fuel vapor fluid conduits.
The fluid conduit, however, preferably includes a first and a second layer. The first layer preferably contains the first material and the second layer preferably contains the second material. The first material, which withstands the higher mechanical stresses, is preferably placed radially outside of the second material.
There are preferably more than two layers and first and second materials are preferably contained in alternating layers. A fluid conduit constructed in this manner can withstand especially high requirements. The mixture of the two materials can be contained in an additional layer so as to meet even higher requirements, and all layers (i.e., a layer of the first material, a layer of the second material, and a layer of the mixture of the two materials) can be coextruded.
The first material is preferably selected from the group consisting of a block copolymer of hard (crystalline) blocks of polybutyleneterephthalate and soft (amorphous), long-chain blocks of polyetherglycol and a thermoplastic polyester elastomer based on polybutylenenaphthalate. These substances bridge the gap between rubber/elastomer and high performance plastics and combine the characteristic strength and processability of plastics with the flexibility, tensile strength and impact strength of rubber/elastomer.
The second material is preferably selected from the group consisting of polybutyleneterephthalate, polyethyleneterephthalate, polybutylene-naphthalate and polyethylenenaphthalate.
The thickness ratio of the layers are preferably selected so that alone the fluid conduit has a sufficiently high clamping force so as to be securable on a pipe socket against unintended pulling off under certain predetermined rated conditions.
The overall thickness of the second layer(s) is preferably 10 to 70% of the overall wall thickness of the fluid conduit.
One of the layers may have a reinforcement selected from the group consisting of glass fibers, steel fibers, glass balls and minerals, as well as a mixture of at least two of these reinforcement materials. A fluid conduit having such a reinforcement can withstand especially high mechanical loads.
To avoid an electrostatic charge and the associated danger of creating a spark, one of the layers may be electrically conductive or antistatic.
The fluid conduit can be sheathed with a flame protection layer. The flame protection layer is preferably made from a reusable material and is joined, by fusion, with the first and/or second material (e.g., by a thicker thermoplastic polyester elastomer).
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Darby & Darby
Dye Rena L.
Rasmussen GmbH
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