Basis for formulation design of PVC blown film

basis for formulation design of PVC blown film

PVC blown film is mainly used as packaging material and covering material in agriculture. As an agricultural film, the requirements are very high. In terms of quantity, it should quickly meet the needs of the vast rural areas. In terms of quality, it should be durable, able to withstand wind, rain and sun exposure. The price should be low, suitable for the needs of the poor and lower-middle peasants. Therefore, when designing the formula of PVC film for agriculture, the following points must be considered:

(1) There is sufficient thermal stability: the processing temperature of extrusion blow molding film is relatively high (Mold temperature up to 210 °C) Only when the degree of plasticization is good can the products with good appearance and uniform thickness be blown into the head. In order to adapt to the characteristics of the blow molding process, the formula must be considered not to decompose at high temperatures.

(2) It has good aging resistance: during the use of agricultural films, plasticizers volatilize due to sunlight; Due to rain, soil burial, etc. , the plasticizer is extracted; At the same time, when exposed to air for a long time, polyvinyl chloride itself will decompose HCl under the influence of heat, light and other external conditions, thus rapidly occurring thermal aging. These effects will make the film deteriorate and brittle, and finally lose its use value. Therefore, the anti-aging problem of agricultural film directly affects its use, cost and development prospect. If the service life of the same film can be doubled, it will not only reduce the cost, save materials, but also solve the quantity problem. The main contradiction in the use of thin films is the anti-aging problem, so it should be studied as the focus. In the selection of plasticizers, the coordination of stabilizers, as well as the addition of other special additives, the aging resistance of agricultural films should be improved.

(3) There must be a certain softness, especially at low temperatures. Because the agricultural film on the vegetable field is used in the winter, the temperature is low, the wind is strong, plus snow or hail, so if the film's low temperature softness is not good, it will break and freeze the seedlings.

(4) In order to reduce costs, try to use raw materials with a wide range of sources and low prices. Such as stone grease and chlorinated paraffin.

(5) The problem of stickiness is not very prominent on agricultural films, because its production season and use season are mostly in winter. Packaging Film must consider the problem of hot weather sticking.