Development of antifogging and drip free polyethyl

Development of polyethylene anti fog drip film

1 preface

the most important use of polyethylene drip free film in agriculture is as greenhouse film. Plastic greenhouses play a vital role in the early sowing and ripening of vegetables, melons and fruits. They provide fresh vegetables throughout the year and make a great contribution to meeting people's living needs. Polyethylene drip free film is made of a certain proportion of linear low density polyethylene (LLDPE), a certain proportion of low density polyethylene (LDPE) (sometimes added with a certain proportion of EVA), and a certain proportion of drip free masterbatch after extrusion and blow molding. The main function of plastic greenhouse is to improve the temperature in the greenhouse. In addition to the low thermal conductivity of plastic film as a polymer material, which can reduce the heat loss in the shed, the silicon containing inorganic mineral fillers such as talc powder and kaolin in the drip free masterbatch can also significantly improve the thermal insulation of the shed film, and the increase of the temperature in the shed will inevitably lead to the evaporation of ground water. At present, the drip free agents in the polyethylene drip free film masterbatch used by most agricultural film manufacturers (or produced by themselves), such as 540B, 622a or w94, only have drip proof effect, which leads to a large fog in the shed, so that flowering vegetables such as cucumber, watermelon, eggplant and so on are prone to disease, affecting the yield and harvest. Polyethylene antifogging and drip free film is made by adding a certain proportion of antifogging agent perfluorane in the production of the original drip free masterbatch, so that the produced drip free film has a certain antifogging property, solves the difficulty of large fog in the shed, and makes a contribution to reducing the diseases and pests of vegetables, especially flowering vegetables, and improving the yield of vegetables

2 experimental formula

2.1 process formula

takes LLDPE as 70 parts, as shown in table 1:

Table 1 PE antifogging and drip free film formula raw material name ratio/part

lldpe 70

ldpe 15

eva 5

drip free masterbatch (including antifogging agent) 10

2.2 resin selection

lldpe resin is generally selected with a melt index of 1.5 ~ the company's raised investment projects.The panel shows that the color filter film material of 2.0g/10min is better, because the smaller the melt index is, The results showed that the higher the molecular weight of the resin was, the higher the molecular weight was, the higher the fracture strength, hardness, toughness, aging stability, melt viscosity and environmental stress cracking resistance of the resin were; For the convenience of extrusion and blow molding, we can't choose the one with low melt index. Therefore, 7042 produced by Qilu Petrochemical Company is ideal at present. According to the above principles, LDPE is produced by Daqing Petrochemical Company for 18D, EVA is produced by Beijing organic chemical plant (VA content is 5), and drip free masterbatch (including antifogging agent) is qy-104 produced by our factory

2.3 function of EVA

eva is a kind of thermoplastic resin with rubber elasticity, which has good toughness, flexibility, stress cracking resistance and adhesion. EVA is blended with polyolefin resin as modifier, which adds elastic particles to PE molecular chain. Due to the low glass transition temperature and low viscosity of EVA, when it is blended with PE, an appropriate second phase is formed with the increase of EVA. Because both groups have ethylene groups and good compatibility, they have a strong toughening effect on PE, and enhance the ability of PE to bear external forces and solvents, so as to enhance the toughness, cold resistance, drip free effect and durability of anti fog effect of the film

2.4 antifogging effect of antifogging agent

antifogging agent perfluoroalkane forms a core in the film from fluorine inorganic substances, which can absorb the water in the air in the shed, inhibit the evaporation of water on the surface of the film, and promote the effect of drip free agent and drip free; All the water on the surface of these films flows down to the soil through the film surface under the action of drip free agents, so as to reduce the water in the air in the shed and achieve the effect of anti fog

although complicated 3 production process

batching measurement → mixing → feeding → extrusion → blow molding → coiling → down coiling temperature difference can be controlled at ± 2 ℃

Table 2 control temperature of each section of extruder

extruder 1 Section 2 section 3 section 4 section 5

thickness/℃ 170 180 190 185 180

4 Summary

take the fog proof and drip free film with a width of 9m and a thickness of 0.08mm as the test shed, and the test results are shown in Table 3

Table 3 application test effect

content of antifogging agent in film/% antifogging effect in antifogging period

0.102 ~ 3 months generally

0.123 ~ 4 months better

0.144 ~ 6 months very good

film with general thickness of 0.06 ~ 0.07mm, antifogging agent content in film 0.14%, antifogging effect is good; For a film with a thickness of 0.08mm, the antifogging effect can be achieved if the content of antifogging agent in the film is 0.12%; If the greenhouse is used for a short time, a 0.08mm thick film with an antifogging agent content of 0.10% in the film is also acceptable

with the continuous improvement of people's living standards, the demand for vegetables is increasing. In order to increase the output of vegetables and reduce diseases, it is necessary to pay the "packaging tax" for insect pests. The promotion and use of polyethylene anti fog and drip free film will be expanded day by day

information source: excellent information Plastic