What are the types of greenhouse film

There are four main types of greenhouse films commonly used in my country: the first is polyvinyl chloride (PVC) greenhouse film; the second is polyethylene (PE) greenhouse film; the third is ethylene-vinyl acetate copolymer greenhouse film; the fourth is The species is a light-adjustable agricultural film. These types of shed films have similarities and differences in nature, and thus have different use effects. (1) Polyvinyl chloride (PVC) shed film has good thermal insulation, light transmittance, weather resistance, softness, and easy modeling. It is suitable as an outer covering material for greenhouses, greenhouses and small and medium-sized arch sheds. The disadvantage is that the specific gravity of the film is large (1.3 g/cm3), the coverage area of ​​a certain weight of shed film is 1/3 less than that of polyethylene film (PE), and the cost increases; it becomes hard and brittle at low temperature, and it is easy to soften and relax at high temperature; After the additives are precipitated, the film surface is vacuumed, which affects the light transmission, and the residual film cannot be burnt due to the generation of chlorine gas. The main products of polyvinyl chloride shed film are: ①No anti-aging additives are added in the film making process of ordinary PVC shed film, and the service life is only 4-6 months. being phased out. ②The PVC anti-aging film is formed into a film by adding anti-aging additives to the raw material. The effective use period is 8-10 months, and it has good light transmission, heat preservation and weather resistance. It is the main material for covering in greenhouses and small and medium-sized arched sheds. It is mostly used for cultivation in early spring and late autumn. ③PVC non-drip anti-aging film (PVC double anti-shed film) has both anti-aging and dripping properties, good light transmission and heat preservation, non-drip performance can last for 4-6 months, and safe service life is 12-18 months It is widely used and is the preferred covering material for high-efficiency and energy-saving solar greenhouses, and it is more effective as a greenhouse covering material. ④ PVC weather-resistant non-drip dust-proof film has weather-resistant drip-resistant performance, the surface of the film is treated, the amount of plasticization and precipitation is less, the dust absorption is lighter, the light transmittance is improved, and it is more beneficial to winter and spring cultivation in solar greenhouses and greenhouses. (2) Polyethylene (PE) shed film is light in texture (specific gravity is about 0.96 g/cubic centimeter), soft, easy to shape, good in light transmission, non-toxic, suitable for all kinds of shed film and mulch film, and is the main agricultural product in my country. Film varieties. The disadvantage is that it has poor weather resistance and thermal insulation, and is not easy to bond. If the greenhouse film is produced, additives such as anti-aging agent, non-dropping agent, heat insulating agent, etc. must be added to meet the production requirements. The main products are: ① Ordinary PE shed film (also known as pe blown agricultural film) is a white film that is directly blown from raw materials without adding anti-aging additives. It is widely used in greenhouses and small and medium-sized sheds. The shed has a service life of only 4-6 months, and can only grow one season of crops, wastes energy, increases labor, and is gradually eliminated in production. ②PE anti-aging film (also known as longevity film, anti-aging film) is made by adding anti-aging auxiliaries to PE resin and blowing to form a film. The thickness of this shed film is 0.08-0.12 mm, the service period can reach 12 to 18 months, and it can be used for 2-3 seasons of crop cultivation, which not only prolongs the service period, reduces the cost, saves energy, but also greatly increases the output and output value. Agricultural film varieties that are mainly promoted in facility cultivation. ③PE non-drip anti-aging film (also known as double anti-film, long-life dripping film) also has dripping, weather resistance, light transmittance and good thermal insulation, the anti-fog effect can be maintained for 2-4 months, and the aging resistance life It can last for 12-18 months. It is a variety of agricultural film with complete performance and wide use. It can not only be used in greenhouses and large and medium-sized greenhouses, but also suitable for energy-saving solar greenhouse cultivation in early spring. ④PE insulation film is a covering material that can prevent infrared radiation from radiating into the atmosphere, which can increase the temperature of the greenhouse by 1-2 °C, and has a better application effect in cold areas. ⑤PE multifunctional composite film has many functions such as no drip, heat preservation, weather resistance, longevity, and some have the function of blocking ultraviolet rays, which reduces the transmission of ultraviolet rays in the shed. Some can inhibit the formation of sclerotinia ascomyci and Botrytis cinerea spores. Use period of up to 12-18 months. (3) Ethylene-vinyl acetate copolymer (EVA for short) shed film: (add a certain proportion of eva), EVA resin is a new agricultural film material used in agriculture in recent years. , thermal insulation and weather resistance are stronger than PVC or PE agricultural film. EVA agricultural film covering can increase production by about 10% compared with other shed films, can be used continuously for more than 2 years, does not deform before aging, can be easily recycled after use, and is not easy to cause soil or environmental pollution. (4) Light-adjustable agricultural film The light-adjustable film made of rare earth and other functional additives added to PE resin can selectively transmit light and is a new covering material that can make full use of solar energy. Compared with shed film, the effect of heating and heat preservation in the shed is good, the crop biochemical effect is strong, and it has the functions of early maturity, high yield, and improved nutrient composition for different crops. Rare earth can also absorb ultraviolet rays and prolong the service life of agricultural film. Among them, the special purple film for leafy vegetables (leek film) is to add purple masterbatch and weather-resistant, heat-insulating, drip-free masterbatch into the film, and then blow molding to form a film. The film is slightly blue-violet, reducing strong light, increasing temperature, early growth period, high quality and high yield. It is suitable for the cultivation of chives and various green leafy vegetables.