Electricity: conductors and insulators – Conduits – cables or conductors – Insulated
Reexamination Certificate
2001-02-28
2003-04-01
Nguyen, Chau N. (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Insulated
C428S317700, C442S374000
Reexamination Certificate
active
06541707
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to the use of an adhesive tape as a bandaging tape for cables, the cables having a PVC-free sheath.
Electrical and electromechanical components, and the sheathing of electrical leads, frequently comprise polymeric materials, polyvinyl chloride (PVC) representing the most important plastic, owing historically to its availability and to its excellent materials properties and insulating properties.
In particular, sheathings of copper wires consist predominantly of PVC, unless conditions such as high-temperature requirements necessitate alternatives.
In the past, self-adhesive tapes for the mechanical and electrical protection of such cables were developed, such self-adhesive tapes being as generally and extensively used for protecting and insulating, and bandaging, electrical leads and components.
The self-adhesive tapes permit a long-term union to be produced without damage occurring to the cable as a result of interactions between adhesive tape and cable sheathing. The additives in the plasticized PVC, in particular, tend to migrate, and necessitate adhesive tapes tailored specifically to such materials.
Therefore, adhesive tapes having a PVC film backing, in particular, have become established: firstly on account of their mechanical properties, but secondly on account of minimized compatibility problems, since at least backing and substrate consist of the same material.
For specialty applications such as the wrapping of lengths of lead or cable harnesses in domestic appliances, machinery, and especially vehicles, moreover, there is widespread use of self-adhesive tapes which possess a textile backing, for example, a woven polyester or viscous staple fabric.
In discussions concerning the environmental compatibility of PVC, the trend is to replace this material by alternatives. Electrical components and accessories, and also the sheathing of copper cables, are increasingly being produced with other plastics, with more stringent applications involving the use, besides fluoropolymers and thermoplastic elastomers such as Amitel® [DSM Engineering Plastics] or Hytrel® [DuPont], predominantly of polyester plastics.
For the cost-sensitive mass sector, with less stringent temperature requirements, the use of polyolefinic materials is on the increase, especially since the metallocene technology made it possible to formulate for mechanical properties similar to those of plasticized PVC; an additional factor is that the polyolefins per se exhibit outstanding insulating effects on the basis of their chemical composition as pure hydrocarbons.
For cable harnesses in vehicles, as well, the trend is in favor of PVC-free leads of this kind, while components such as plug connections, switches, grooved tubes, etc., are already manufactured predominantly from PVC-free materials.
Lengths of electrical lead, or components, that are wrapped with self-adhesive tapes are required to ensure reliable functioning over the entire lifetime of the product as a whole, such as that of a vehicle, for example. If inappropriate adhesive tapes are selected, there may be instances of incompatibility during the life of the product, which may result in damage to the cable, such damage possibly extending to extreme embrittlement—corrosion and short circuiting, with the risk of failure of the entire electrical/electronics system, are the possible consequences. Especially in the case of vehicles such as automobiles or trucks, the compatibility requirements are very stringent; in the passenger compartment, temperatures may peak at up to 80° C., while in the engine compartment much higher temperatures are present for long periods.
Therefore, for the field of use of the cable wrapping tapes, a long-term test over 3000 hours, in accordance for example with FORD specification S95 GG 14K 024 BA, has established itself as a standard test—specimen cable harnesses are stored at the test temperatures and after fixed periods of time, usually every 500 hours, are bent around a mandrel of defined diameter and then examined for damage; this test runs over a total period of 3000 hours. In addition to purely visual evaluation, in some cases an electrical insulation test takes place as well. The test temperatures are guided by the fields of use of the cable harnesses and are, for example, 90° C. for woven fabric tapes employed in the passenger compartment, in accordance with FORD S95 GG 14K 024 BA. For applications in the engine compartment, long-term temperatures of 125° C. or more are required.
For cable wrapping applications of this kind, adhesive tapes having a tapelike backing based on wovens or stitchbonded webs are known, woven tapes having been obtainable for a relatively long time and tapes having a stitchbonded web backing being described, for example, in DE 94 01 037 U1. Pressure-sensitive adhesive coatings are preferably employed as the adhesive coating.
DE 44 42 092 C1 describes such an adhesive tape, based on stitchbonded webs, which is coated on the reverse of the backing. DE 44 42 093 C1 is also based on the use of a web as backing for an adhesive tape; in this case, a cross-laid fiber web is described which is reinforced by the formation of loops from the fibers of the web; i.e., a web known to the person skilled in the art as Malifleece. DE 44 42 507 C1 likewise discloses an adhesive tape for cable bandaging, but bases it on so-called Kunit or Multiknit webs.
DE 195 23 494 C2 discloses the use of an adhesive tape having a backing comprising nonwoven material for bandaging cable harnesses, said tape being coated on one side with an adhesive. The web employed in accordance with the invention is a spunbonded web of polypropylene, which is thermally consolidated and embossed with the aid of a calender, the embossing roll having an embossing surface of from 10% to 30%, preferably 19%.
DE 298 04 431 U1 likewise discloses the use of an adhesive tape having a backing comprising nonwoven material for the bandaging of cable harnesses, the proposed spunbonded web consisting of polyester.
DE 298 19 014 U1 discloses adhesive tapes based on a web which is consolidated with air and/or water jets. The disadvantage of these backings, despite the mechanical consolidation, is that it is impossible by this technique to rule out the extraction of individual long threads and an adverse effect on the adhesive properties. In the case of very extensive consolidation of the backing, other advantageous backing properties, especially for the harnessing of cables in automobiles, can no longer be obtained.
WO 99/24518 A1 describes an adhesive tape where the backing material is a nonwoven whose suitability for adhesive tape applications derives from the specific selection of fibers or filaments having a fineness of more than 15 denier and from a sheet layer applied additionally by extrusion. The additional extrusion coating required is not the only disadvantage for use; in particular, the restriction to very thick fiber material results in a coarse web which lacks the typically soft, textile character. Denier [den] is a unit which is common in the textile industry, and originates from France, for the linear density (fineness) of yarns. The unit is produced by the equation:
linear
density
=
filament
mass
filament
length
,
a filament having the linear density one denier [1 den] if the weight of a filament 9000 m long is 1 g; correspondingly, 1 g/1000 m=1/9 den (cf. Römpp Lexikon Chemie-Version 2.0, Stuttgart/New York, Georg Thieme Verlag 1999).
In the case of the desired substitution of PVC by polyolefins, in particular, it is found that self-adhesive tapes employed to date consistently have problems with the long-term compatibility. The range of damage which occurs extends from slight cracking in the cable sheathing, owing to embrittlement, through to complete failure by crumbling of components and cable sheathing following prolonged storage.
Adhesive tapes comprising silicone adhesive compositions are k
Harder Christian
Höwe Bernd
Külper Klaus
Lange Frank
Nguyen Chau N.
Norris & McLaughlin & Marcus
tesa AG
LandOfFree
Use of an adhesive tape as cable bandaging tape does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Use of an adhesive tape as cable bandaging tape, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Use of an adhesive tape as cable bandaging tape will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3080752