(1) Polyvinyl chloride (PVC) shed film has good heat preservation, light transmission, weather resistance, softness, and easy shape. It is suitable as the outer covering material for greenhouses, large sheds and small and medium arch sheds. The disadvantage is that the film has a large proportion (1.3 g/cm3), and the coverage area of a certain weight of the shed film is 1/3 less than that of the polyethylene film (PE), which increases the cost; it becomes hard and brittle at low temperatures, and it is easy to soften and relax at high temperatures; After the additives are precipitated, the film surface will absorb dust, which will affect the light transmission. The residual film cannot be burned because of the generation of chlorine.
The main products of PVC greenhouse film are:
①No anti-aging additives are added in the process of ordinary PVC greenhouse film, and the use period is only 4-6 months. It can produce one-season crops, wastes energy, increases labor and investment, and is gradually being eliminated.
②PVC anti-aging film is formed into a film by adding anti-aging additives to the raw material and calendering it. The effective use period is up to 8-10 months. It has good light transmittance, heat preservation and weather resistance. It is the main material for covering large sheds and small and medium-sized arch sheds. It is mostly used for early spring and late autumn cultivation.
③PVC non-drip anti-aging film (PVC double anti-shed film) has anti-aging and dripping characteristics at the same time, good light transmission and heat preservation, drip-free lasting for 4-6 months, and safe service life of 12-18 months , It is widely used and is the preferred covering material for high-efficiency and energy-saving solar greenhouses. It is better to make greenhouse covering materials.
④ In addition to weathering and drip-resistant performance of PVC weather-resistant and drip-resistant film, the surface of the film has been treated to reduce the amount of plasticization, lighter dust absorption, and improved light transmittance, which is more beneficial for winter and spring cultivation in solar greenhouses and greenhouses.
(2) Polyethylene (PE) greenhouse film is light in texture (specific gravity is about 0.96 g/cm3), soft, easy to shape, good in light transmission, non-toxic, suitable for making various greenhouse films and mulching films, and is the main agricultural industry in my country. Varieties of membranes. The disadvantages are: poor weather resistance and heat preservation, and difficult to bond. If the greenhouse film is produced, additives such as anti-aging agents, non-drip agents, and thermal insulation agents must be added to meet the requirements of production.
