Blown plastic film tubing prodn. - using various prodn. parameters which are determined and singly or collectively altered to match each other e.g. for increasing output rate

摘要

Films are produced by a process involving one or more of (a) the blown film is cooled to recrystallisation pt. of the polymer and/or the cylindrical part of the blown tubing adjacent to the bubble is cooled and/or (b) the dia. of the bubble is confined around its recrystallisation and/or (c) the surface area of the bubble is increased between the annular gap of the die and the recrystallisation zone and/or (d) the speed of the material feed through the gap in the die is reduced and/or (e) the material is stretched in the annular gap before it leaves there and/or (f) the annular die and blowing head are disengaged and/or (g) the temp. of the melt in the annular die gap is reduced or changed so as to adjust the viscosity and/or temp. and/or (h) the specific heat, thermal conductivity, density or melt viscosity of the polymer used is altered by suitable additions to the material and/or its prodn. process. ADVANTAGE - System enables the various prodn. parameters to be determined and adjusted to match each other e.g. for the purpose of increasing output. Process is obtd. without having to use complicated rheological or thermodynamic procedures. (0/6)