Woven Sacks

MFI  Measuring   The  melt flow index  ( MFI ) is a  measure  of the ease of flow of the melt of a  thermoplastic   polymer . It is defined as the  mass  of polymer, in grams, flowing in ten minutes through a capillary of a specific diameter and length by a pressure applied via prescribed alternative gravimetric weights for alternative prescribed temperatures.Polymer processors usually correlate the value of MFI with the polymer grade that they have to choose for different processes, and most often this value is not accompanied by the units, because it is taken for granted to be g/10min. Similarly, the test conditions of MFI measurement is normally expressed in kilograms rather than any other units. The method is described in the similar standards  ASTM  D1238 and ISO 1133. Melt flow rate is an indirect measure of molecular weight, with high melt flow rate corresponding to low molecular weight. At the same time, melt flow r...

Corona Treatment   Watt-Density = Power /(area x time)  US Units: W/(ft 2/minute)  [KW setting x 1000] / [Line Speed (ft/min) x width (ft)]  Example:   Treater output = 3.0 kW; line speed = 450 fpm; Treater width = 5 ft  The watt-density is: (3.0 x1000)/(450 x 5) = 1.7 W/(ft 2/min) Important:  You must determine optimum watt-density for each film and for each set of running conditions.  Some starting suggestions:  BOPP films: 3.0 – 4.0 WD  OPET films: 1.5 – 2.0 WD  BON films: 0.5 – 1.5 WD  (metric units are factor of 10 higher) Why do I need corona treating and how does it work? Corona treating increases the surface energy of plastic films, foils and paper to improve wettability and adhesion of inks, coatings and adhesives. Treating works best when a substrate is treated at the time of extrusion and in-line prior to converting. Corona treating increases quality and productivity through improved print quality, fas...