Patent Application
20070295525
The present invention is concerned with a vehicular cable that utilizes insulation that is non-halogenated and heavy metal free. In particular, the invention pertains to an automotive wire harness of a non-halogenated composition.
Environmental regulations dictate that the material selection in the vehicular industry needs to be halogen free and heavy metal free compositions especially for the vehicular cables. Typically, polyvinyl chloride (PVC) is utilized because of its combination of competitive raw materials costs and desirable properties. These properties include processibility, toughness, chemical resistance and ability to withstand temperatures typical for many applications in automotive environments.
Unfortunately, the chlorine content of PVC limits its disposal at the end of the life of the vehicle. Also there are concerns about effects on health and the environment by PVC by-products and PVC plasticizer. Accordingly, therefore, a replacement for PVC has long been sought with an intent to find competitive cost efficient replacements. In addition, performance must be taken into account including high temperature endurance, toughness processability and also reduction in weight.
It is therefore desirable to have a material that is a vehicular cable insulation, is cost effective and still achieves desirable characteristics such as lack of halogens and heavy metals, appropriate conductivity, temperature resistance, scrape abrasion resistance, resistance to heat aging, resistance to automotive fluids and resistance to flame and in particular to be capable of meeting the standard ISO (International Organization for Standardization) 6722 and offers all these properties with a reduction in weight.
Described is an insulated non-halogenated, heavy metal free vehicular cable comprising an inner core of a copper based metal wire having a cross sectional area of at least about 0.1 mm2, and an outer insulation, covering the length of the inner core, comprised of a thermoplastic polyphenylene ether composition that has no halogen or heavy metal added thereto, the insulated cable capable of meeting the testing standard ISO 6722.
Further objects and advantages of the invention will be apparent from the following description and appended claims, reference being made to the accompanying drawings forming a part of the specification, wherein like reference characters designate corresponding parts in several views.
With increasing electronic content in automobiles there is an ever growing need for miniaturizing the size of the cables that provide resistance to physical abuse and provide resistance to flame and automotive fluids among other requirements to be met for the automotive industry such as ISO 6722. It has been found to be particularly desirable to utilize an insulated non-halogenated, heavy metal free vehicular cable containing a copper based metal wire that has a diameter of at last about 0.1 mm or more and an outer insulation covering the length of the inner core comprised of a thermoplastic polyphenylene ether composition which has no halogen or heavy metal added thereto.
By “non-halogenated” is meant that the polymeric material that is utilized has no halogen material that is added to the composition, as a desirable component of the composition.
By “heavy metal free” is meant that no heavy metal such as mercury, hexavalent chrome, cadmium, lead and the like are added to the metal core, as a desirable component of the metal composition.
By “copper based metal” is meant that the metal wire is comprised of greater than 50% by weight of the metal being copper, or copper alloyed with other metal components as is well known in the industry yet maintaining suitable electrical conductivity. Well known copper based alloys may be used such as HPC-80EF, trademark Phelps Dodge.
By “polyphenylene ether” is meant a thermoplastic polymeric material which is commercially available and generally are polymers of monohydroxy aromatic-materials. Other readily available materials are 2, 6-xylenol or a 2, 3, 6-trimethylphenyl and polymers thereof. Polyphenylene ether (PPE) is also known as polyphenylene oxide (PPO) and is described in the literature. See U.S. Pat. Nos. 3,306,874, 3,306,875; 3,257,357; and 3,257,358, which are herein incorporated by reference.
Frequently polyphenylene ether materials are a blend of other thermoplastic or cross-linked ethylenically unsaturated materials such as polyolefinic materials, styrene or styrene butadiene or polyacryamide and the like. These materials are commercially available such as Noryl, Luranyl, Ultranyl or Vestoblend, trademarks of GE. Some materials that may be utilized include Noryl WCV072, WCV072L-111, and the like of GE.
It has been found that the ultra thin cable and cable wall that is utilized in the present case even at a small cross section of 0.1 mm2 give a very satisfactory result in abrasion cycling tests such as that called for in ISO-6722.
The cross sectional area of the copper wire can range from about 0.1 to about 3 square millimeters, such as 26 AWG to 12 AWG, alternatively 0.13 to 1.5 square millimeters.
The insulated cable of the present invention is prepared utilizing normal well known commercially available equipment where the desired polyphenylene ether polymer is fed to an extrusion machine where the molten viscous polymer is passed through a die, as shown in
Turning now to a description of the drawings.
During the extrusion process of the insulated vehicular cable 10, the copper based core is fed through the middle of die 20 entering the back end 22 of the die and exiting from the die at 24. The die has a central portion 26 through which the copper based wire 14 passes. The hot viscous PPE will be passed into the space 28 at the entrance end 22 of the die 20 and proceeds to envelop the copper wire. The die begins to narrow at 30 as PPE is extruded with the copper based wire passing from 30 through exit 24 of the die. At the exit 24 of the die, the insulated vehicular cable 10 of the present invention is obtained. The cooling process as described above and the packaging of the cable follows thereafter.
The diameter of the insulated vehicular cable 10 of the present invention can vary substantially. A cable diameter that has been found useful is between 0.85 and 0.92 mm in case of 0.13 mm2 cable. Other dimensions of an insulated vehicular cable would be one that has approximately 0.13 square millimeters of wire as its cross sectional area but which is used to form the embodiment shown in
As indicated above a wide variety of commercially available extruding equipment may be utilized such as an extruder identified as BMD60-24D or a Nokia Maillefer, and the like.
The die utilized in the present invention may be manufactured from a wide variety of commercially available materials such as D2 hardened tool steel.
Following the procedures outlined in ISO-6722, scrap abrasion resistant using 7(N) load and 0.45 millimeter needle was used on three sets of cables, the first being compressed halogen free cable ISO ultra thin wall cable referred as CBFUS, the second ISO thin wall cable referred as HFSS and the third ISO thick wall cable referred as HF. The test results are identified in tables 1 and 2 below.
*Wire Size (square mm)
*Wire Size (square mm)
Following the procedures outlined in ISO-6722 a number of tests were so performed where the cross sectional area of the copper wire varied as well as the diameter of insulated polyphyenelyene ether varied as is shown in tables 3-4.
While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all of the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive rather than limiting and that various changes may be made without departing from the spirit or the scope of the invention.
