Patent Application
20080011377
For instance, the hose may show different crosslinking degrees in axial direction and/or in circumferential direction, i.e., it may comprise substantially rigid and flexible sections.
The configuration of substantially rigid and flexible sections depends on the use desired for the hose 1.
The crosslinkable material can be a thermoplastic material or a thermoplastic elastomer. By analogy with the base polymers of the thermoplastic materials, corresponding thermoplastic elastomers such as TPE-A and TEE-E types (optionally, glass fiber-reinforced) are crosslinkable by irradiation by adding co-activators/crosslinking promoters. Particularly suited materials are copolyamide elastomers (TPE-A), elastomeric polyetheresters (TEE-E), polyurethane elastomers (TPE-U), elastomer-modified thermoplastics, and mixtures thereof.
In an exemplary embodiment the crosslinkable material is used in the form of a single-component system. The single-component system is particularly easy to handle and to provide. After having been shaped, the hose is sequentially crosslinked in a downstream step. Optimum adhesion of the different segments is accomplished by material identity. This, in turn, enhances flexibility with respect to construction and design of the hose and is conducive to the implementation of optimized properties. As an additional advantage, production wastes or unused materials can be re-used because the crosslinking operation is only carried out in a subsequent operative step. If TPE-A or TEE-E is used for this embodiment as the crosslinkable material, it is of advantage if these materials are modified for cross-linking with functional groups or double bonds in the material. This is e.g. accomplished by the use of partly unsaturated polyethers or soft blocks of polyetherester. This accomplishes not only a crosslinking of the amide or ester functions in the partly crystalline phases, but the soft blocks are also crosslinked in a three-dimensional way.
In a further exemplary embodiment, the crosslinkable material is used in the form of a two-component system. This is above all of advantage if increased demands are made on the stiffness of the hard component, particularly in connection with increased temperatures and pressures. Hard/soft composites consisting of a suitable thermoplastic material and of the corresponding thermoplastic elastomer, such as PA6, PA 612 and TPE-A (GF optional) or PBT and TEE-E, can be used as the materials. Thanks to the use of the two-component system in the case of chemically equivalent materials, adhesion can be improved in the area of the boundary layer due to material compatibility. An optimized adhesion is accomplished in the boundary layer by interdiffusion of the polymer chains in the area of the boundary layer and by subsequent crosslinking. Moreover, this optimizes the mechanical dynamic properties as well as the temperature stability, particularly of the soft component.
The sectionwise crosslinking of the hose can be accomplished by irradiation. β- or γ-rays are here particularly preferably used.
Preferably, the crosslinkable material further comprises a crosslinking promoter or co-activator as the additive component. The crosslinking promoter is only needed in small quantitative fractions. The crosslinking degree or crosslinking density of the hose can each time be set in accordance with the requirements by selecting the crosslinking promoter and its content. Examples of suitable crosslinking promoters/co-activators are trifunctional unsaturated compounds, such as triallylisocyanurate (TAIC), triallylcyanurate (TAC), trimethylallylisocyanurate (TMAIC), trimethylolpropanetriacrylate (TMPTR). These compounds react in different ways to irradiation, resulting in different crosslinking degrees in the case of an identical dose.
The hose according to
An exemplary manufacturing method of the hose will be described hereinafter with reference to the enclosed figures:
First of all, a flexible hose 1 is provided, comprising at least one crosslinkable material. The hose 1 can be entirely made in an injection molding process and is substantially uncrosslinked and flexible. Subsequently, the sections of the hose 1 that are no to be further crosslinked are masked or covered with a masking 4. The masking 4 prevents those sections 3 of the hose 1 that are not to be further crosslinked from being subjected to further crosslinking. The masking 4 is configured in the case of irradiation crosslinking as a radiation-shielding means, e.g. as a metal foil 4.
After the sections 3 of the hose 1 that are not to be further crosslinked have been masked, the sections 2 that are to be further crosslinked and not covered by the masking 4 are subjected to the action of a crosslinking agent 6 and are crosslinked. In the case of irradiation crosslinking, the sections 2 of the hose 1 to be crosslinked are irradiated by a radiation source 5, the crosslinking reaction being started in the irradiated portions of the crosslinkable material. High-energy beta (β-) or gamma (γ-) rays are preferably used as crosslinking agents 6. The properties of the crosslinkable material can be influenced by way of a targeted selection of the co-activator content and the radiation dose and can be set in compliance with the desired future use.
After the hose 1 has been subjected to the action of the crosslinking agent 6, the masking 4 of the hose 1 is removed. In the sections 2 which are to be crosslinked and pertain to the crosslinkable material of the hose 1, the degree of crosslinking is locally increased. In the sections 3 of the crosslinkable material of the hose 1 that have been covered by the masking 4, the crosslinking degree is much smaller than in the sections 2 acted upon by the crosslinking agent 6. For instance, the hose 1 or the crosslinkable material of the hose 1 comprises different crosslinking degrees in portions and, since there is a direct relation between strength and crosslinking degree, it has degrees of strength differing from portion to portion.
The features of design of the hose according to the invention, particularly the selection of the material, including the additive component, the layered structure, the corrugation, the curvature and the arrangement of the substantially uncrosslinked and crosslinked portions can be defined at will and can each be determined with respect to the specific application of the hose.
It will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102006032751.9 | Jul 2006 | DE | national |
