Casting PA film and production technology
1. Casting PA film and its raw materials used: PA film has the advantages of high strength, good toughness, good transparency, good heat resistance and cold resistance, can be used in the range of 50-180 ℃, high temperature cooking materials can be used and frozen Packaging materials; it also has good oxygen barrier properties, is a barrier material. PA varieties used to produce film are: PA6, PA12, PA66 and so on. For the packaging of meat products and sausages, the required oxygen permeability of 20-80 cm / (m2-24 h), of which PA6 is the most ideal.
2. Production equipment: The extruder is generally used Φ90 - Φ150 mm single screw extruder, L / D is 28-35, screw geometric compression ratio of 3.4-4.0, with mixing screw. The nose with multi-tube head, lip lip length longer than the CPP length.
Cooling device: PA film cooling device and CPP different, to be cooled in two steps. Casting roller for cold oil roller, hot oil roller, roller surface temperature of 90 -100 0C. It is then cooled with a water-cooled roll and the film is cooled to room temperature. If you use CPP rapid cooling Meng method, PA film wrinkles serious, not good smoothness of the product. Other equipment Other equipment and CPP production line is basically the same.
3. Production process parameters: PA6 is now an example, with Φ90 mm single screw extruder, L / D of 32, the screw geometric compression ratio of 3.5, with MFR of 1.8 a 2.0 g / 10 min of PA6 (Japan Dongli Company CM1021-XF). Extrusion temperature Extrusion temperature of cast PA6 film Cooling temperature The surface temperature of the first chill roll is 90 --- 100 ° C and the surface temperature of the second chill roll is 20-40 ° C.
4. The main product quality indicators: cast PA film is currently no national standard and standard superscripts, the above-produced cast PA6 film measured the main physical and mechanical properties are as follows. Film thickness 30 μm; longitudinal tensile strength 70 MPa; longitudinal elongation at break 280%; transverse tensile strength 60 MPa; transverse elongation at break 260%.
5.LDPE film varieties: LDPE film is mainly used for building and all kinds of waterproof materials and composite heat sealing substrate. This film is currently no national standard and department standard, the main physical and mechanical properties of reference indicators: tensile strength "20 MPa; Elongation at break) 300%.
LLDPE film LLDPE cast film has the following two.
① self-adhesive film, the film is LLDPE as the main raw material, adding a certain percentage of a resin made by extrusion casting. The film can be properly through the oxygen and carbon dioxide gas, can maintain the fresh food color and inherent flavor. This film scalability, flexible and self-adhesive, easy to use. This film performs GB 10457-89; film thickness 0.006-0.021 mm.
② self-adhesive winding film The film and the preservation film belong to the same type of product, mainly for commodity box packaging; this film is generally relatively thick, usually 0.02-0-03mm; the film is currently no national standard and the Ministry of superscript.
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