Nonwoven fabric composite for hygiene articles etc. - by extruding layer of molten polymer onto spun-bonded web or staple fibre web under reduced pressure

摘要

Composite non-woven fabric (I) is obtd. from spun-bonded web or a web of staple fibres (II) and a strip of polymeric material (III) which is applied to (II) while still molten. The process is carried out under partial vacuum. Also claimed is a coating system for carrying out the process, which includes a sheet die (103), cooling devices (104), and a rotating vacuum cylinder (102) with perforations around its perimeter. (II) is pref. a layer of unbonded, matted fibre or bonded felt, made of polyamide, polyester or pref. polypropylene (PP) with unit wt. 10-60 (pref. 10-20) g/m2, or of biodegradable material, pref. based on cellulose, viscose, gelatin fibres or natural polyester e.g. Biopol (RTM), poly-hydroxybutyric acid or poly-epsilon-caprolactone; (III) is ethylene homo- or co-polymer, elastomeric polyamide, polyurethane or elastomeric polyether, or a biodegradable material (as for II); (III) is 5-40 (pref. 20) microns thick, and is transparent, opaque, matt-finished or coloured, and is pref. permeable to water vapour; a layer of coupling agent (pref. EVA copolymer grafted with a small amt. of adipic acid anhydride) (IV) is introduced between (II) and (III), or the molten strip of (III) is subjected to oxidative pretreatment or corona treatment, before application to (II); the vacuum cylinder has internal chambers. USE/ADVANTAGE - (I) is used for the prodn. of nappies, adult nappies, sanitary towels, undersheets for beds and operating covers. The process (esp. the vacuum-coating) enables the prodn. of a mechanically strong composite material (I) which retains the textile character of (II) (appearance, feel, permeability to water vapour and air) and its softness.