Films breathability

Conveyor belt and moving web reactors give a piston-flow reaction environment. The polymer layer is usually thin enough so that heat transfer is not a serious issue, but the confinement of vapors to meet environmental requirements can be expensive. Thus waterborne or condensation polymerizations without by-products (eg polyurethanes) are preferred. Ultraviolet and electron beam curing is common. Applications include photographic and xerographic films, breathable fabrics, coated abrasives, and printed films, as well as polymers manufactured on belt flakers. 

Waterproof Finishes. Waterproofing results from coating a fabric and filling the pores with film-forming material such as varnish, mbber, nitroceUulose, wax, tar, or plastic. The materials may be appHed as hot melts, eg, waxes or some polymers, as solvent solutions, or as aqueous latexes. The continuity of the film provides the water resistance. Except for tents, tarpauHns, and covers, coated fabrics have been largely replaced by plastics, and by fabrics treated with water and oU repeUents that do not reduce permeabUity to air and water vapor. Eabrics are also commonly laminated to films, such that the total stmeture is waterproof (15), or in some cases water-resistant but breathable (16). 

Lower-density E-plastomers have found alternate use in cast film processes to make elastic film laminates with good breathability which contain laminates of liquid impermeable extensible polymeric films with extensible-thermoplastic-polymer-fiber nonwovens and nonwoven webs of polyethylene-elastomer fibers as the intermediate layers. The development relates to a breathable film including an E-plastomer and filler that contributes to pore formation after fabrication and distension of the film. The method and extent of distension is designed to produce a breathable film by stretching the film to form micropores by separation of the film of the E-plastomer from the particulate solids. This film is useful for manufacture of absorbent personal-care articles, such as disposable diapers and sanitary napkins and medical garments. In detail, these constructions comprise a liquid impermeable extensible film comprising polyolefins. The outer layer contains extensible-thermoplastic-polymer-fiber nonwovens, and an elastic intermediate layer contains nonwoven webs of fiber E-plastomers. The intermediate layer is bonded to the film layer and the outer... 

Plastic Suppliers Inc., a US extruder of blown film for labels and envelopes, has produced the world s first blown film from NatureWorks PLA. It was hitherto thought that PLA was unsuitable for blown film extrusion. Plastic Supplies claims that its EarthFirst film is 100% compostable, has high gloss, optimum clarity and transparency, high moisture vapour transmission rate, flavour retention, odour barrier, is breathable and is US Food and Drug Administration (FDA) compliant. Areas of application for EarthFirst include window carton film for food packaging, label film, floral wrap film, shrink film and envelope film. 

The formation of microvoids (or micropores) in drawn /3-PP is a well-known feature, used successfully to produce breathable films and membranes. Macroscopically their occurrence is correlated with an opacification (i.e. whitening) of the specimen. Their amount can, for example, be measured at given strain rate/draw ratio by liquid porosimetry (e.g. mercury intrusion), gas absorption or by the determination of the density of the deformed sample [129,177,178]. 

The damage process is accompanied by numerous microvoids, the development of which has been utilized for waterproof and/or breathable films. Other interesting segments are fibers, glass-fiber reinforced PP, thermo-formable grades and piping systems. 

The machine operates as follows. The substrate film 5 is fastened between frames 7 and 8 and is heated by heater 4 to a viscous-flow state. Chuck 2 travels upwards and air is exhausted through its breathable surface. The substrate film imitates at curing the profile of the chuck. Film 10, fed by unit 9, is subjected to embossing by needle roller 11 and treatment by Cl. The inhibiting liquid is applied onto the film from vessel 12 using castor 13 fit with a porous pad on its outer surface. The Cl is applied onto the film areas over the packed article contours. The inhibited film covers articles 6 on substrate 5, the air is evacuated and the pack is sealed. The machine economizes... 

General Description Elf Atochem Pebax Resins, breathable resins, are polyether block amides (PEBAs), thermoplastic elastomers made of a flexible polymer and a rigid polyamide. Extruded films made with Pebax are compact, thoroughly waterproof, and breathable. 

Permeability Pebax is permeable to oxygen and other gases such as CO2, N2, and C2H4. Pebax s high breathability lets water vapor (or perspiration in the textile applications) go through films at a very high rate.fi ]... 

Table 43-01. Film Properties of Atofina Pebax Breathable Films...

Film Applications Copolyester TPE film and coating markets divide into breathable and non-breath-able applications.f ]... 

Non-breathable applications include wholesale food packaging, especially applications that require freezing products in the bag, monolayer and multilayer films, and vacuum bagging.t ... 

Breathable Films, Pebax, Elf Atoehem, R-04.96, Atofina Chemieals, Ine. 

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