Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Web – sheet or filament bases; compositions of bandages; or...
Patent
1995-12-20
1997-06-24
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Web, sheet or filament bases; compositions of bandages; or...
424448, 424449, A61F 1302, A61L 1516, A61K 970
Patent
active
056415060
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a medical patch material having a support coated with an even and porous spread of a pressure sensitive hot-melt adhesive, and to a process for its production.
According to the art, medical patch materials are composed of supporting materials of textile fabrics and/or films which are coated with adhesive substances of the group of natural rubber, synthetic rubber, polyvinyl ether, and polyacrylate copolymers based on solvents or dispersions.
Among these adhesive masses, natural rubber adhesives are disadvantageous because of their high allergization risk and their low aging resistance; for this reason their medical application has increasingly receded into the background. Dispersion adhesive masses have the disadvantage that solubilization of the adhesive masses occurs because of their low moisture resistance, therefore they too did not succeed in the market. The solvent acrylate adhesives, widely used today, have the disadvantage that the employed solvent has to be evaporated under heavy power and technical expenditure and must then be burnt or even recovered and directed to waste disposal.
Modern pressure sensitive hot-melt adhesives of synthetic-rubber adhesives based on block copolymers have not gained importance in the market until today, because their low permeability to water vapor prevents reliable, long-term adhesion on the human skin which releases about 500 g/m.sup.2 /24 h of water in state of rest.
Increasing the water-vapor permeability in a medical patch material by means of a porous spread, for example by using screen printing coaters, has been known for some time for the medicinal application of patch materials. However, the disadvantage of patch materials coated in this manner, wherein the adhesive is applied only in the form of islands and not coherently, lies in the fact that the film patches thus manufactured cannot ensure impermeability to bacteria, and that individual threads tend to unravel in case of textile fabrics. This not only concerns the optical impression but this sometimes renders reliable application impossible in case of elastic supporting materials.
Moreover, pressure sensitive hot-melt adhesives applied by means of screen printing have the property of giving a hemispherical spread and not a cylindrical one. In direct coating this results in the fact that the adhesive surface facing the skin, as compared with the applied adhesive amount, is very small and depends on the application pressure; and in transfer coating, the adherence to the supports is insufficient even if the lamination pressure is high. On the other hand, pressure sensitive hot-melt adhesive coatings having a coherent adhesive substance and tack-free spots arranged in the form of islands, provided that these were formed by means of gravure printing, failed to gain importance in the medical application because spreads of only up to 30 g/m.sup.2 could be achieved by means of gravure coating. If higher spreads were applied, the fine structures achieved were unsatisfactory and the required porosity reduced to a considerable extent. In addition, these comparatively thin spreads resulted in low internal elasticity which was not sufficient to compensate surface differences between the human skin and the supporting material, which were caused by movements. Therefore the edges of the patch material frequently peeled in case of small spread amounts.
It is the object of the present invention to provide a medical patch material having a support coated with an even and porous spread of a pressure sensitive hot-melt adhesive and a process for its production. This makes it possible--by avoiding the above discussed disadvantages and technical limitations--to coat pressure sensitive hot-melt adhesives based on block copolymers having a suitable viscosity by means of gravure printing on supports of textile fabrics and/or films or foils in such a manner that with sufficient porosity the amount of adhesive applied is sufficient to ensure a reliable and permanent adherence of the patch materials
REFERENCES:
patent: 4645502 (1987-02-01), Gale et al.
patent: 4911916 (1990-03-01), Cleary
patent: 5133972 (1992-07-01), Ferrini et al.
patent: 5262165 (1993-11-01), Govil et al.
Ludwig Karin
Reinhold Karl-Heinz
Seeger Kurt
Talke Volker
Lohmann GmbH & Co. KG
Page Thurman K.
Shelborne Kathryne E.
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