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What resin to choose when making a cast film machine?
What is a cast film machine? A cast film machine is a non-stretched, non-oriented flat extruded film made from melt casting and rapid heating with a cast film machine. There are two ways of single-layer drool and multi-layer co-extrusion drool. Compared with blown film, it is characterized by slow production speed, low output and excellent transparency, gloss and thickness uniformity of the polymer. But we are making a cast film machine, do we know the importance of resin selection? What kind of resin should I choose?
(1) The first is the selection of resin varieties
The choice of resin varieties is basically whether the desired cast film machine can be produced. Resins with properties close to the purpose of modification should be selected to save the amount of additives added. Wear-resistant modification, three small wear-resistant resins PA, POM, UHMWPE; should be considered first; again, if the resin modification is uniform, three uniform resins PS, PMMA, PC should be considered first.
(2) The second is the choice of resin brand
Many manufacturers have never paid much attention to this when making a cast film machine. Different brands of the same resin have very little difference in performance, and a brand whose performance is close to the purpose of modification should be selected. For example, heat-resistant modified PP can be selected within the range of PP grades with a heat distortion temperature of 100 to 140 °C. We should choose a PP grade with a self-resistance of 140 °C, such as PP-4012 of Xiaohan Oil.
(3) Again, it is the choice of resin fluidity
The abstraction of this step can only be achieved by trial, and there is no clear standard. The viscosity of various plasticized materials in the formula should be close to ensure processing fluidity. For materials of different viscosities, transition materials should be added to reduce the viscosity gradient. For example, PA6 is often added as a transition material in the PA6 toughening and flame retardant formula, and HDPE is often added as a transition material in the PA6 toughening and flame retardant formula.
Different processing methods require different flow properties.
Different varieties of plastics have different fluidity. Since then, plastics have been classified as low-flow plastics, high-flow plastics, and never-flow plastics, as follows:
Low flow plastics - polystyrene, high impact polystyrene, -butadiene-styrene copolymer, polyethylene, polypropylene, polyamide, etc.
High flow plastics - PC, MPPO, PPS, etc.
Plastics that never flow - PTFE, UHMWPE, PPE, etc.
The same plastic also has different fluidity, mainly because the molecular weight and molecular chain distribution are different, so the same raw material is divided into different grades. Different processing methods require different fluidity, so the grades are divided into injection molding grade, extrusion grade, blow molding grade and calendering grade.
Different modification purposes require different fluidity, such as high filling requirements and poor fluidity, such as magnetic plastics, filling materials, halogen-free flame retardant cable materials, etc.
(4) Finally, the selectivity of resin to additives
The literal meaning of auxiliaries, as the name suggests, is the catalyst that promotes the smooth forming of the cast film machine. For example, PPS must not add lead-containing copper additives, and PC must not use antimony trioxide, which will lead to depolymerization. In addition, the pH of the additives should be the same as the pH of the resin, so that they will react with each other and the consequences will be very serious.
Cast film machine can be used to produce PE, CPE, EVA and other plastic films, as well as transparent films, embossed films (patterns can be sampled according to customers), optical films, etc.
Cast film machine performance: not hard or brittle at low temperature, not sticky at high temperature of 45 °C, bad hand feeling, light weight, non-toxic, no irritating odor, and large environmental pollution after use.
Changzhou ZL-Machinery Co.,Ltd.