How to design the formula of calendered film?

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How to design the formula of calendered film?

(1) The formula design is mainly based on

as calendering film, and generally has the following requirements for the formula:

① good thermal stability. The calendering film process is long and the temperature is high (Generally at 180'Around 12) , And contact with hot metal roller for a long time, so the thermal stability of the formula is required to be higher.

② good aging resistance. Under the action of heat, light and oxygen, polyvinyl chloride film will become brittle, resulting in the decline of service performance. In order to maintain good service performance for a long time, the formula must provide good aging resistance.

③ has certain softness. Especially for products used outdoors, they should have certain softness at low temperature to prevent film cracking under harsh weather conditions.

④ it is dustproof and anti-fog. Due to the internal plasticizer exudation and film electrostatic effect, as well as the dust in the atmosphere falling on the surface of the agricultural film is not easy to fall off, the light transmittance of the agricultural film will decrease after a period of use (Generally, it will drop by 10% to 20%) In this way, the greenhouse temperature will be correspondingly reduced, affecting the growth of crops. Therefore, to improve the dustproof property of agricultural film, Human xylitol glyceride should be added to the formula.

(2) Selection of raw materials

① selection of resin. Generally choose suspension polymerized resin, soft products generally choose loose type II resin, and pay attention to'Fisheye'As small as possible.

② the choice of plasticizer. The amount of plasticizer generally added to the film is 45 ~ 50 copies. The plasticizer commonly used in film formulations is dioctyl phthalate (DOP)Because its comprehensive performance is better. A part of diisooctyl Ester, disecondary octyl Ester and dinonyl ester can also be used instead. Dibutyl phthalate is also added to polyvinyl chloride films because it has good compatibility with polyvinyl chloride, good molding and low price, but is generally used with DOP. If you want to improve the low temperature resistance, you can add dioctyl sebacate.

③ selection of stabilizer. Heat stabilizers are mostly metal soap stabilizers, such as barium/cadmium soap and barium/cadmium/zinc soap. The ratio of barium to cadmium is generally (3 ~ 5) : 1 The effect is good, the dosage is 2-3 copies.

④ the choice of other additives. In order to improve the weather resistance of soft products and prolong the service life of products, a small amount of chelating agent, ultraviolet absorber and antioxidant can be added.

in order to prevent film dust absorption, a dust-proof agent can be added to the film production formula, which belongs to static electricity prevention agent. Among them, quaternary ammonium compounds are generally used as external antistatic agents for soft polyvinyl chloride. In order to prevent the formation of droplets on the surface of the film, anti-fog drops need to be added to the film, which is also an electrostatic preventive agent.