Production technology of extrusion casting method

日期:2019/8/7 9:02:06 / 阅读: / 来源:本站

Production technology of extrusion casting method
1. Selection of resin
The extrusion casting method requires the resin to have a good melt flowability, and the melt flow rate of the resin is generally larger than that of the resin used in the extrusion blown film method.
For example: CPP, generally 10 ~ 12g / 10min;
CPE, generally 3~10g/10min;
CPA6, generally 1.8~2.0g/10min
In addition, the choice of resin model, but also consider the end use of the film. For example, retort sterilization
CPP, which requires a temperature resistance of 140 ° C or higher, requires the use of block copolymerized polypropylene of the cooking type PP; transparent PP packaging film, the point is less crystal point, high transparency, the use of film grade PP homopolymer. PE stretch film (wound entangled, self-adhesive food wrap film), need to use film-grade polyethylene without additives (lubricants, opening agents); medical polyethylene film (medical gloves, tape base), requires better Resilience and softness can be blended with EVA.
2. Extruder temperature setting
3. Cooling roller temperature setting
Polypropylene and polyethylene are crystalline plastics, and the casting melt is quenched in a cooling roll to accelerate the crystallization rate, and the crystallinity is also small, the film is soft, the transparency is high, and the tensile strength is also high. However, if the chiller temperature is required to be low, the cooling cost required for the chilled cooling water temperature is too high. Generally, the CP cooling roll temperature is 18-25 ° C; the CPE cooling roll temperature is 20-30 ° C.
Polyamide is a highly crystalline polymer with a narrow melting temperature range. The melt viscosity is very sensitive to temperature changes. It must be cooled in two steps to produce a flat, wrinkle-free film. In the production of CPA6, hot oil is required to be introduced into the chill roll, so that the surface temperature of the roll is controlled to be around 90-100 ° C (much lower than the melt temperature); then, the film enters the water-cooled double-sided cooling roll, cooling roll The surface temperature is approximately 40 °C.

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