GB686762A - Improvements in or relating to the treatment of continuous films of water-sensitive, organic, non-fibrous materials - Google Patents

Abstract

Continuous film of water-sensitive, organic, non-fibrous material is continuously conditioned and slit by passing it through a conditioning apparatus comprising a partial drying chamber 26 wherein the water-content of the film is reduced from a value which is in equili-brium with normal atmospheric relative humidity of 35 to 45 per cent to a lower value which is in equilibrium with an atmospheric relative humidity of 15 to 25 per cent and a rehumidifying chamber 27 wherein the partly dried film is exposed to steam, water vapour or moist air to readjust its water content to a value which <PICT:0686762/IV (a)/1> is in equilibrium with an atmospheric relative humidity of 45 to 65 per cent, the film then being slit on machine 33 before being rewound at 34. Rollers 25 are adapted to be lowered to a position 28 to withdraw the film from the chambers when necessary. As an alternative, retractable screens may be positioned within the chambers to protect the film from heat and humidifying agent, when movement of the film through the chambers is interrupted. The process is applicable to films of regenerated cellulose, lowly substituted cellulose esters, ethers and ether-esters, gelatine and alginic derivatives. Specification 591,616, [Group XVI], is referred to.