The hot stage polarized light microscope is used to identify different types of crystal points, and the contaminants-foreign contaminants crystal points can be seen under the microscope.
When crystal spots of foreign contaminants appear, it is necessary to improve the cleanliness of the protective film production workshop; improve the material storage and transportation process, keep the resin packaging bag clean; strictly control the production order, and avoid cross-contamination between different types of raw materials when batching.
After heating and melting the film body, clear crystal points or degradation products-highly crosslinked/oxidized crystal points can still be seen;
The crystal points disappear after the main body of the film is heated and melted, but the crystal points-lightly crosslinked crystal points can be seen again after cooling down;
When highly cross-linked/oxidized crystal points occur, it is necessary to replace batches of raw materials with fewer crystal points; reduce processing temperature; add additional antioxidants; optimize equipment and replace with high-quality screws.
The crystal points disappear after heating and melting the main body of the film, but the crystal points do not recover when the temperature is lowered—the crystal points that are poorly plasticized.
When there is a poorly plasticized crystal point, it is necessary to avoid mixing pellets and powder; pay attention to the pumping process of raw material particles to avoid the generation of raw material powder due to friction; avoid simply blending raw materials with very large melting points; if the formula is It is required that raw materials with large melting points must be mixed; the temperature of the diyi zone and the second zone of the screw needs to be lowered to avoid premature melting of low-melting raw materials, and the filter screen can be encrypted to increase the shear in the metering section.https://www.pe-protectionfilm.com/