Surgery: splint – brace – or bandage – Bandage structure – Skin laceration or wound cover
Reexamination Certificate
2000-07-03
2003-04-29
Lewis, Kim M. (Department: 3761)
Surgery: splint, brace, or bandage
Bandage structure
Skin laceration or wound cover
C602S041000, C602S045000, C602S076000, C442S269000, C442S305000, C428S317900, C428S295400, C428S297400, C428S297100, C428S902000
Reexamination Certificate
active
06555730
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a backing material for medical purposes, preferably for orthopaedic dressings and bandages, which is coated on at least one side completely or partially with a selfadhesive composition.
2. The Related Art
As backing materials for medical purposes, numerous materials based on films, wovens, knits, nonwovens, gels or foams have already been disclosed and are also. employed in practice. The materials, which are often coated with a self-adhesive composition as well, are required to be skin-compatible, generally permeable to air and water vapour, and also easy to model and conformable. Based on these requirements, a very thin or soft backing is frequently preferred. For handling and in use, however, the backing materials are also required to be of sufficient strength and possibly of limited extensibility. Furthermore, the backing material should retain sufficient strength and low extensibility even after becoming wet through.
Thin backings, especially those made of nonwovens, are highly permeable to air and water vapour. For certain applications, however, their strength is too low and their elongation too high.
Specific applications, an example being tapes for functional tape dressings for the prophylaxis and therapy of injuries, disorders and altered states of the musculoskeletal system, require inelastic backings having high strength in the direction of stress. This is achieved by using woven-fabric backings, usually of cotton or viscose. Backing materials of this kind, with appropriately high basis weight, are generally cost-intensive. High conformability and modelability can only be achieved by means of a woven fabric of relatively low strength. When such a fabric is stressed, however, it generally exhibits a degree of elongation, which is undesirable for its use.
When the dressings listed become wet through, they generally lose strength or become more extensible. This is likewise undesirable for their use and has to date been compensated by more frequent changing of dressings, which, however, is cost-intensive.
Lamination with reinforcement threads has also been disclosed in the prior art by German Patent 571 244, although the reinforcement threads employed therein are not of high tenacity. The document, then, generally gives no indication of an inelastic backing.
In addition, AU 73555/74 describes by way of example a glass filament-reinforced backing material for medical application based on foam.
U.S. Pat. No. 4,668,563 describes a glass fibre-reinforced material which, however, is elastic. All backing materials mentioned, however, are not reinforced by stitching.
DE 44 42 092 and DE U 94 01 037 describe adhesive tapes based on stitchbonded webs which are partially coated on the reverse side of the backing. Such adhesive tapes are used preferably in cable bandaging.
DE 44 42 093 is also based on the use of a nonwoven 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. DE 44 42 507 likewise discloses an adhesive tape for cable bandaging, but bases it on so-called Kunit or Multikunit webs.
A utility or special suitability of these backing materials for medical purposes, however, cannot be inferred from the documents cited. In particular, the publications give indications neither of sufficient skin compatibility of the adhesive compositions nor of functionally secured bonding on the skin or an advantageous permeability to air and water vapour.
U.S. Pat. No. 4,773,238 describes a fibre web with lengthwise overstitching, the stitching seams being intended to amount to no more than 20% by weight based on the weight of the total nonwoven. Proposed in accordance with the invention is the utility as an insert for filters in dust filtration.
U.S. Pat. No. 4,967,740 gives a general disclosure of backing materials for use in medical supply, which are produced in a one-step process. In this process, the backing is impregnated simultaneously with an elastomer and with a release solution. In this way, the material can be presented without release paper on a roll.
In a listing of a large number of appropriate backings, mention is made, inter alia, of overstitched nonwovens, without the skilled worker being given any indication as to how the nonwoven should, specifically, be configured in order to meet the requirements placed on a medical backing.
Highly adhesive orthopaedic bandages and other medical products are usually coated over the whole of their area with a rubber adhesive composition. These adhesive compositions then permit a high bond strength on the reverse face of the backing, which ensures a stable functional dressing in the case of systems of circularly applied dressings with a plurality of plies.
The object of the invention was to provide a nonwoven-based backing material which is suitable for medical requirements and does not have the disadvantages known from the prior art. These inventions and other objects of the invention are achieved by the invention described herein.
SUMMARY OF THE INVENTION
Accordingly, a nonwoven overstitched by means of yarns is used as backing material for medical purposes, the number of stitches on the nonwoven being advantageously at least 5/cm, preferably from 7/cm to 50/cm. The ultimate tensile stress strength of the backing material is at least 30 N/cm, preferably from 40 to 450 N/cm, with particular preference from 50 to 250 N/cm, and the backing material is coated partially or over its full area on at least one side with a self-adhesive composition.
The yarns preferably have a water absorption of less than 30%, with particular preference less than 20%. The water absorption can be regenerated by the atmospheric humidity.
DETAILED DESCRIPTION OF THE INVENTION
Accordingly, materials which can be used for the yarns are, advantageously, polymeric fibres made from polypropylene, polyester, polyamide, aramid or polyethylene, and also mineral fibres such as glass fibres or carbon fibres. In addition it is also possible to use multistrand yarns or mixed multistrands, especially Sirospun yarns. For specific applications, single- or multi-strand fibre blend yarns may also be employed. Furthermore, the yarns can have been at least partly coloured in order to make the backing material more visually appealing.
For specific applications, the yarn can also be elastic. From this there is then regenerated an elastic base support having an elongation of up to 250% at a load of 10 N/cm. Mention may be made here, for example, as a polyamide yarn (Lycra®, DuPont) [sic]. A backing material of this kind generates a compression force of from 0.2 N/cm to 10 N/cm at an elongation of from 20% to 70% and is used in compression technology.
In the case of the alternative embodiment of the subject-matter of the invention, a nonwoven is used as backing material for medical purposes. In this case, the nonwoven is reinforced by the formation of stitches formed by loops from the fibres of the web, the number of stitches on the web being advantageously at least 5/cm, preferably from 7/cm to 50/cm. The ultimate tensile stress strength of the backing material is at least 30 N/cm, preferably from 40 to 450 N/cm, with particular preference from 50 to 250 N/cm, and the backing material is coated partially or over its full area on at least one side with a self-adhesive composition.
The backing materials are based on known nonwovens which are mechanically consolidated either by overstitching with separate yarns or by looping. In the first case, the resulting structures are the web-yarn stitchbonds. For their production, a fibre web is taken, which can, for example, be in cross-plating configuration, and is overstitched with separate yarns in pillarstitch formation or tricot formation.
These nonwovens are known by the name “Maliwatt” (from the company Malimo) or Arachne.
With the second type of consolidation, again, preferably a cross-plated web is taken. In the course of the consolidation operati
Albrod Andreas
Ganschow Frank
Himmelsbach Peter
Keite-Telgenbüscher Klaus
Peeters-Bendix Daniela
Beiersdorf AG
Lewis Kim M.
Norris & McLaughlin & Marcus
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