Plastic film is also called film plastic, including mulch film (also known as agricultural film). The main component is polyethylene, which is used to cover farmland to improve ground temperature, maintain soil moisture, promote seed germination and rapid growth of seedlings. The role of inhibiting weed growth.
There are many kinds of plastic films, and some non-agricultural films contain substances that are toxic to plants, which are easy to cause phytotoxicity. Therefore, the first choice is to use agricultural film. Plastic agricultural film can be divided into rice film and vegetable film according to its use. The aging resistance of rice membranes is lower than that of vegetable membranes, so it cannot be misused.
Different types of agricultural film have the highest and lowest temperature adaptation limits, and should pay attention to their environmental conditions when using, and should not exceed the following range. The film has a low resistance to the right-angle tearing, and the arch shed should not have a sharp edge, so that the arc-shaped skeleton is preferred. Metal scaffolding, the surface temperature difference changes drastically, easy to make the film aging, it is best to use a woven bag or straw rope to wrap the metal, or apply white anti-rust paint on the metal.
When covering the shed film, it should be straightened and tightened, and the bottom is buried in the soil about 15 cm to keep the film flat and wide, and it is difficult to accumulate rain and dust. After the film is coated, the film must be pressed. After rain or snow, remove the rain and snow accumulated on the film in time to prevent the film from being crushed.
The welding of the film is to ensure quality. Different types of films have different soldering temperatures. Generally, the polyvinyl chloride film needs about 130 ° C, the polyethylene film needs about 110 ° C, and can be welded with a 100-200 watt electric iron or a 200 ° C electric iron. Before welding, prepare a smooth wooden board with a width of 5-6 cm, which is best for nailing the window screen. The welded two-layer film is placed on the window screen, and a waste newspaper is placed on the film, and then the electric iron or electric iron is pressed at the seam for 1 to 2 times. It is necessary to pay attention to the temperature at any time, the temperature is low, and it is easy to take off after welding. If the temperature is too high, the film is easily melted and broken.
In recent years, due to the rapid development of China's film-covering cultivation technology, the shortage of national agricultural film has been caused. In addition to increasing the production of agricultural film, it is also very important to use agricultural film economically to improve the utilization rate.
However, the plastic film is also very easy to break, and after the damage occurs, it is not kept warm and does not moisturize. So you need to fix it:
First, the heat supplement method:
Use a soldering iron or electric iron. This method is only applicable to polyvinyl chloride films. When repairing, spread the film on a flat table and cut a piece of similar agricultural film slightly larger than the hole. First wipe the place where the two are connected with a damp cloth, then dry it with a dry cloth, dry it and dry it. The film is placed on the hole, and a piece of slightly thick cellophane is placed on it, and the electric iron is gently moved on the cellophane to melt the film at the interface, and after cooling, the two films are stuck together.
Second, the bonding method:
It is repaired with the organic solvent cyclohexanone (hexolone), but it is best to buy a glue that is specially used to repair and replenish the film (such as polyvinyl chloride intestinal binder). The method is to wipe the interface clean first, apply glue with a brush, let it dry for 2-3 minutes, paste the patched film, and use it after 2 hours of adhesion.
Third, the seam method:
The thicker agricultural film is damaged and can be repaired by the seam method. That is, the old film is first washed and dried, and then a piece of the same film is placed on the top, and the needle or the sewing machine is used to make up the block at the skin hole, or to sew the break.
Fourth, water supplement method:
This method is suitable for greenhouses. Wash the stripped area first. According to the area of ​​the damaged area, cut the film slightly larger than the hole, then apply water, or use the natural water beads on the shed to drain the air between the films, flatten the two films, and squeeze the water beads hard.
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