Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Reexamination Certificate
1999-09-30
2002-08-20
Zirker, Daniel (Department: 1771)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
C428S040100, C428S198000, C428S3550AC, C428S356000, C442S149000, C442S151000, C442S374000, C442S375000
Reexamination Certificate
active
06436528
ABSTRACT:
The invention relates to an adhesive tape having a tapelike backing comprising a nonwoven material which is wet-laid or mechanically preconsolidated and additionally consolidated adhesively using a chemical binder, and is coated on at least one side with an adhesive, and to its use.
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 fibre web is described which is reinforced by the formation of loops from the fibres 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, the 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 individual fibres, other advantageous backing properties, especially for the harnessing of cables in cars, 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 fibres 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 fibre material results in a coarse web which lacks the typically soft, textile character. Denier 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
lenght
Adhesive tapes having a woven backing satisfy stringent technical requirements but are laborious to produce, owing to the poor productivity of the weaving process, are expensive, and have a tendency for the adhesive composition to strike through. Adhesive tapes having stitchbonded web backings, although simple in their construction, nevertheless show considerable disadvantages in practical use, such as problems owing to the heterogeneous web structure with reinforcing parallel stitches. Furthermore, the production rate of this technology is limited even with modem high-performance units.
Furthermore, with a single-sided adhesive tape having a conventional Malifleece as backing material, i.e. a Malifleece which has not been additionally bonded, it is necessary to treat the reverse in order to prevent delamination of the backing and/or extraction of individual fibres or tufts of fibres from the surface, especially in the case of unwinding from the roll. Alternatively, this objective can be attained by introducing a release paper between the individual plies of adhesive tape during the operation of winding the adhesive tape roll, although this is undesirable for the producer owing to the additional cost factor and to the user owing to waste disposal and handling problems, quite apart from the fact that siliconized release papers are as far as possible avoided, especially in coating sectors.
In the case of stitchbonded or otherwise mechanically consolidated webs (needlefelts or air- and/or water-jet consolidated webs) as well, the individual fibres of the web are nevertheless still displaceable with respect to one another and can be torn out individually under stress. This applies both to fibres in the sheetlike backing and, quite particularly, to fibres at the surfaces. It is extremely laborious, and hardly economically feasible, to conduct such consolidation, possibly by passing the web several times through the consolidation process, to such an extent that the fibre assembly no longer suffers delamination—in this case there would, however, inevitably be a loss of desired properties such as tearability by hand, textile character, damping properties, etc.
If, therefore, at this point, in the manufacturing process of the backing and/or of the adhesive tape, there is a failure to ensure additional improvements, then the fibres extracted during the unwinding of the adhesive tape roll have a marked adverse effect on the adhesive properties of the adhesive tape. They are responsible for poor visual qualities and may even ruin the entire functional capacity of the adhesive tape.
The object on which the present invention is based is therefore to improve an adhesive tape in such a way that the disadvantages of the prior art do not occur to the same extent, if at all.
This object is achieved by means an adhesive tape as specified in the main claim. The subclaims relate to advantageous developments of the adhesive tape and to a particularly advantageous use thereof.
The invention accordingly provides an adhesive tape having a tapelike backing of nonwoven material which is coated on at least one side with an adhesive, the untreated web being a fibre web which in a first step is mechanically consolidated, for example, by the formation of loops from fibres of the web or by needling, stitching or air- or water-jet treatment, or else is a wet-laid web which has been laid hydrodynamically. This intermediate then undergoes additional, adhesive consolidation by means of an added binder.
Preconsolidated webs are produced, for example, on stitchbonding machines of the the “Malifleece” type from the company Karl Mayer, formerly Malimo, and can be obtained, inter alia, from the companies Naue Fasertechnik and Techtex GmbH. A Malifleece is characterized in that a cross-laid web is consolidated by the formation of loops from fibres of the web.
The backing used can also be a web of the Kunit or Multiknit type. A Kunit web is characterized in that it originates from the processing of a longitudinally oriented fibre web to form a sheetlike structure which has the heads and legs of loops on one side and, on the other, loop feet or pile fibre folds, but possesses neither filaments nor prefabricated sheetlike structures. A web of this kind has also been produced for many years, for example, on stitch-bonding machines of the “Kunitvlies” type from the company Karl Mayer. A further characterizing feature of this web is that, as a longitudinal-fibre web, it is able to absorb high tensile forces in the lengthwise direction. The characteristic feature of a Multiknit web relative to the Kunit is that the web is consolidated on both the top and bottom sides by virtue of the double-sided needle punching.
Finally, stitchbonded webs are also suitable as an intermediate for forming an adhesive tape of the invention. A stitchbonded web is formed from a nonwoven material having a large number of stitches extending parallel to one another. These stitches are brought about by the incorporation, by stitching or knitting, of conti
Ganschow Frank
Külper Klaus
Chang Victor S
Norris & McLaughlin & Marcus
tesa AG
Zirker Daniel
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