Low density polyethylene mulch film

日期:2022/9/24 8:57:25 / 阅读: / 来源:本站

                                                                                                                                                       Low density polyethylene mulch film
Low-density polyethylene mulch film is a kind of film used to cover the growing ground of crops. In order to meet the needs of different crop growth, mulch can be made into black, red, white, blue and other colors. Insulation, such as potatoes covered with black film, can not only increase production, but also inhibit the growth of weeds; blue film covers the ground where crops grow, which can increase production and increase temperature; red film is suitable for cotton growth; The ground of the garden is covered with silver-gray reflective film, the fruit has good color, early maturity, and can also have the effect of eliminating aphids.
There is also a kind of photodegradable film formed by adding photodegradation agent in low density polyethylene in mulch film. The mulch film is degraded into fragments under the action of light during use, reducing the pollution of the film to the environment.
(1) Selection of raw materials
① The density of low-density polyethylene resin for ordinary mulch film is 092g/cm, and the MFR value of melt flow rate is 0.5~25g/10min. Such as DEX821DFDA7087 of Sinopec Guangzhou Petrochemical Branch; 951-050 brand resin of Sinopec Maoming Company, etc. can be used for extrusion blow molding mulch.
②Colored mulch film is to add 3%~5% color masterbatch or a small amount of colorant to low density polyethylene resin.
③The photodegradable mulch film is to add a certain proportion of photodegradation agent and some other auxiliaries to the low density polyethylene resin.
(2) Selection of equipment and process parameters: The selection and application of equipment and process parameters for extrusion blow molding low-density polyethylene mulch film are exactly the same as those used for ordinary polyethylene blow molding film.
The difference between the extrusion blow molding process of low-density polyethylene mulch film and the ordinary polyethylene film extrusion blow molding process is that the inflation ratio of the film bubble can be slightly larger (the usual inflation ratio is 2.5~3); traction The bubble speed can be slightly faster (the maximum speed can reach 40m/min)
Then roll up into bundles separately. The mold gap is relatively small (generally about 0.8mm); the thickness of the low-density polyethylene mulch film and the recommended use time should be opened at the fold of the finished product Resin LDPE 0.014 0.012 It is recommended to use it! LLDPE plus weathering agent resin LDPE 0.014 0.010 120 100 blend resin 0.010 0.010 plus weathering agent resin 0.008 80 blend resin LLDPE LDPE 0.008 0.012 Note: This regulation is taken from GB/T13735-92 50 0.008 The quality requirements and performance of low-density polyethylene mulching film products should meet the standard GB low-density polyethylene agricultural greenhouse film. Generally, the width and width of the folding diameter are more than 2m. The thickness of the commonly used film is in the range of 0.08~0.14mm. The main purpose is to use it as a vegetable greenhouse, so that the vegetables can be grown in an environment of heat preservation and moisture. According to the needs of the use of the greenhouse film, different raw materials are selected to form the formula, and different products such as ordinary greenhouse film, reinforced greenhouse film, drip-free greenhouse film and longevity greenhouse film can be formed by extrusion blow molding. The performance of ordinary greenhouse film is the same as that of polyethylene film; the strength of reinforced greenhouse film is higher than that of ordinary greenhouse film, and its toughness is better; the longevity greenhouse film has good aging resistance, and the working time is longer than that of ordinary greenhouse film; no The characteristics of the use of drop greenhouse film are that there is less water mist on the film surface, good light transmission, and water droplets can flow into the ground along the film surface.
(1) Raw material selection The ordinary greenhouse film can be formed with LDPE resin produced by Sinopec Group Beijing Yanshan Petrochemical Co., Ltd., and the grade is PE-F-23D006 or PE-FL-23D012. Density at 0919~0.922g/cm3FR at 0.5~1.0g -386-
All PE resins can be used to produce greenhouse film. Enhanced greenhouse film extrusion blow molding can choose the blending ratio of two raw materials: low density polyethylene and linear low density polyethylene, LDPE accounts for about 60%, and LLDPE mixture. Longevity greenhouse film forming raw materials can add 0.4% to the formula of reinforced greenhouse film materials
40% or so. (such as using di-tert-butylhydroxytoluene BHT) and 0.15% antioxidants, if necessary, an appropriate amount of liquid paraffin should be added.
(2) into a large amount
Anti-aging agent, so large-scale extruder should be used. Usually, an extruder with a screw diameter of 90mm should be used to produce a film with a folded diameter of 2m; an extruder with a screw diameter of 150mm should be used for the production of a film with a folded diameter of 4m. In order to improve productivity and ensure the plasticization quality of raw materials, it is best to choose separate screw extrusion raw materials with barrier sections.
The forming die can choose the mandrel as the spiral structure. In order to reduce the weight of the mold, it is best to use the lotus petal mold structure (Figure 6-25).
Figure 6-25 Schematic diagram of the structure of the lotus petal-shaped mold for wide-width film forming: 1 - Lower template; 2 - Fixing nut; 3 - Upper template;
5-mold body; 6-melt runner: 7-mandrel
(3) Process parameters of extrusion blow molding of greenhouse film Process temperature of each section of the barrel: feeding section
140~160℃, plasticizing section 160~180℃, homogenizing section 190~200℃. forming mold
Plastic Extrusion Technician's Manual
180~190℃. Guangzhou stone blowing ratio 2~3, die clearance 1~1.2mm, traction speed 2~20m/min (2
The blown film bubble is cooled by air cooling. The film bubble with a folded diameter of 2m uses a fan with a diameter of 700mm
The length-diameter ratio ring, the frame height is 8m; the diameter of the folded diameter 4m film bubble is 1400mm, and the frame height is 135°C
15m, after cooling and curing, the film width is folded into 2m and rolled. The quality requirements of the low-density polyethylene greenhouse film should comply with the specifications and dimensions specified by the standard GB4455-mold. The specific specifications, dimensions and thickness limit deviations are shown in Table 6
14 and Tables 6-15. For the appearance quality requirements, please refer to Table 6-12.

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