Vacuum Insulation Panel Blocking Membrane Welding Process And Its Microstructureits

Vacuum insulation panel is a kind of super thermal insulation material which is manufactured bythe way of vacuum packaging. Vacuum insulation panel is formed of glass fibre core material andplastic composite barrier membrane. The encapsulated substance of vacuum insulation panel is the hotmelt welding of plastic composite barrier membrane, the accelerated aging and wrinkling of plasticwhich is caused in the process of hot melting will lead to the declining of sealing strength. Soresearching on the vacuum insulation panel blocking membrane welding process and itsmicrostructureits is of great significance to the performance and application of the vacuum insulationpanel.Based on the structure of PA/VMPET/Al/PE composite barrier membrane as the research objectin this paper, the vacuum insulation panel was prepared through vacuum hot melt welding to analysisthe influence of heat sealing temperature, time, pressure on the heat sealing strength. Using coefficientof thermal conductivity, stress intensity factor, crystallinity and thermal sealing strength value as arepresentation, to study the influence of weld inclusions, welding heat affected zone and weld singeon the heat sealing performance of heat sealing side of vacuum insulation panel.From the angle of the polymer chain movement of the sinusoidal theory, analysis the microscopicmechanism of heat sealing, the conclusion was that the heat sealing temperature, time, pressure werethe basic and necessary conditions of complete heat sealing and the heat sealing temperature on theinfluence of the heat sealing strength was the most obvious. Relying on heat transfer theory ofunsteady heat conduction, ideal single-layer barrier membrane thermal model and step by step heatingup in the process of the actual heat sealing model were established. It suggested that the accuracy ofstep by step heating up in the process of the actual heat sealing model was better than idealsingle-layer barrier membrane thermal model5-7℃through the experiments.The research results showed that the better process parameters interval was heat sealingtemperature of160-170℃, heat sealing time of1-2s, heat sealing pressure of0.2to0.4MPa. Usingthe MATLAB neural network toolbox to establish the BP neural network model of heat sealingstrength, the process parameters were optimized, determined the maximum intensity of thecorresponding process parameters for the heat sealing temperature of168℃, heat sealing time of1.8s, heat sealing pressure of0.34MPa. According to the model, the surface of the relationship betweenthe heat sealing strength and heat sealing temperature, time and the heat sealing strength of surface contour were mapped which provided a theoretical basis for intuitive studying the influence ofwelding parameters on the heat sealing strength..