application

PE blow molding film production process

Hopper feeding – material plasticizing extrusion – blowing traction – wind ring cooling – herring splint – traction roller traction – corona treatment – film winding, but it is worth pointing out that the performance of blown film has a great relationship with the production process parameters, therefore, in the process of blowing film, must strengthen the control of process parameters, standardized process operation, to ensure the smooth production, And obtain high quality film products.

Processing and main components of agricultural film

Agricultural film is made of high polymer as the main body, adding appropriate amount of functional additives, after blow molding processing. The ideal material for the shed film is polyolefin, such as polyethylene (PE), polyvinyl chloride (PVC), ethylene – vinyl acetate copolymer (EVA) and other thermoplastics.

Thermoplastics do not have a melting point like low molecular compounds, but melt at a certain temperature interval, within which they are viscoelastic. Using this property, it can be heated into a melting state similar to gum sugar, blowing bubble, cooling, curing, shaping, traction to get a certain size of the shed film.

Classification of agricultural film

1, aging resistance film (longevity shed film). Add a few thousandths of an excellent light stabilizer to the main raw material. Shed film in oxygen environment by light (especially ultraviolet) irradiation, there will be a variety of changes, such as discoloration, surface cracking, mechanical deterioration. The service life of ordinary polyolefin shed film is only 4 to 5 months, while the usual winter agricultural production needs the life of the shed film is 9 to 10 months. The continuous service life of individual regions or individual varieties of crops requires the shed film to be more than 2 years, and the life of flower shed film and ginseng shed film is more than 3 years. The above purpose can be achieved by adding a few thousandths of the excellent light stabilization agent to prepare the longevity shed film.

2, no drop film. A shed film in which some surfactants are added to the main material so that the inner surface of the film does not appear (or rarely appears for a certain period of time) condensation droplets during coating use. In cold winter, the temperature inside the greenhouse is higher than the outside, and the humidity is large, the greenhouse is like an enlarged film hot water cup. Water vapor is easy to reach the dew point after contact with the film, forming water droplets on the inner surface of the film. A water drop is like a lens, when the light from the outside to the shed, the surface of the water will make the light refraction phenomenon, the light can not enter the shed, greatly reducing the light transmittance of the shed film, not conducive to the photosynthesis of crops. If light is focused through a “lens” and hits a plant, it will burn the plant and harm it. Larger drops of water on crops can cause them to rot. After adding some surfactants, the surface of the drip-free film is changed to hydrophobic to hydrophilic, and the water droplets will soon form a transparent water film along the inner surface of the inclined shed film, and the light transmission of the film is not affected.

3, no drop, fog elimination function shed film. Fluoride and silicon antifogging agents were added on the basis of drip-free film. Winter solar greenhouse using general film cover, often produce heavy fog, greenhouse light intensity is reduced, affecting the development of crops, but also easy to cause disease. On the basis of the drip-free film, add fluorine and silicon fogging agent, so that the water vapor in the susaturated state of the shed can more rapidly condense on the surface of the shed film, and under the action of the drip-free agent, the water droplets along the surface of the greenhouse film rapidly auxiliary spread and flow to the ground, this is the drip free, fogging function of the shed film.

4, light shed film (light conversion film). The optical conversion agent is added to the main raw material. In recent years, according to the principle of light ecology, the solar energy conversion technology is applied to agricultural film, that is, the light conversion agent is added to the shed film, the solar energy in the plant photosynthesis is very small into the red orange light favorable to plant growth, improve the photosynthesis of plants in the plastic shed film, improve the utilization rate of light energy of plastic greenhouse, in order to improve the quality of plants. Such as improve fruit sweetness, early maturity, increase production, increase income, beautify the color of flowers and trees.

5, high insulation film. Using high visible light transmittance, infrared blocking effect of high polymer and add infrared absorbent, made of high temperature insulation film. High insulation film can absorb radiant heat as much as possible during the day and reduce radiant heat as much as possible at night. During the day, the sunlight mainly shines into the film with visible light wavelength of 0.3~0.8 micron, which increases the temperature in the greenhouse and absorbs a lot of heat in the soil. At night, there is a temperature difference between the inside and outside, and the soil radiates heat in the form of infrared light with a wavelength of 7-10 microns. Therefore, by using high polymer with high transmittance of visible light and good infrared blocking effect, and by adding infrared absorbent, people have developed high temperature retaining film. At present, great progress has been made in the application of nano-insulation materials on the membrane.

6, multifunctional membrane. According to the processing method classification, there are single layer film and multilayer co-extrusion composite film, the latter is a multifunctional film. For example, 0.1mm film can be composed of 3 layers, its significance is, by adding the most reasonable and economical additives in each layer, give the shed film needed multiple functions. For example, add more drops and fogging agents in the middle layer, and add more light stabilizer in the outer layer.

7, color film. It is produced according to the principle of optics. Under the red film cover, cotton seedlings grew well, the stems were thick, the roots were developed and the survival rate was high. Planting carrots and cabbage with yellow agricultural film can accelerate their growth, and covering cucumber can increase the yield by more than 50%. Using purple agricultural film can greatly increase the yield of eggplant, leek and pineapple; The strawberries under the blue coating bear large and abundant fruit. The advantages of color film in promoting crop production, increasing yield and improving quality are showing broad application prospects.

8. Degradation membrane. It is developed for the “white pollution” caused by waste agricultural film. The residual film of degraded film can decompose itself in a short time under the influence of various natural conditions. Degradation films can be divided into three forms: photodegradation, biodegradation and photobiodegradation. The e starch film and grass fiber film which are being developed in our country belong to degradation films. Samples have been developed and put into small batch production.