Inventory: Analysis of the advantages and disadvantages of current agricultural plastic film

In order to meet the needs of all aspects of agricultural production, agricultural plastic film has a variety of different varieties and specifications. According to the plastic raw materials used, it is divided into polyvinyl chloride plastic film and polyethylene plastic film. According to different manufacturing methods of plastic film, it is divided into pressing film and blown film; according to some special properties of plastic film, there are seedling film, no drop film, colored film, ultra-thin cover film, wide film, {TodayHot} packaging film, etc. There are various specifications depending on the thickness and width of the plastic film.

Polyvinyl chloride and polyethylene plastic film

Polyvinyl chloride film and polyethylene film are the two largest plastic films currently used in agricultural production. Among them, polyvinyl chloride film, because of its good comprehensive performance, is the longest and most popular one in China. Polyethylene film is a variety that has been popularized and applied in recent years. Due to its superior performance and increasing dosage, the performance characteristics of these two agricultural plastic films are briefly compared as follows:

1. Polyvinyl chloride film has high mechanical strength, good anti-aging performance, good elasticity and can be restored after stretching. The mechanical strength of polyethylene film is about 70% of polyvinyl chloride film, toughness and resilience. Poor, light transmission and surface aging performance is not as good as that of polyvinyl chloride film. If sufficient anti-aging material is not added when manufacturing the film, surface cracking and embrittlement may occur prematurely under strong sunlight. However, during use, the mechanical strength of the polyethylene film decreases with time, but is smaller than that of the polyvinyl chloride film.

2. The polyethylene film has a higher gas permeability and a higher heat transfer rate than the polyvinyl chloride film. In general, the heat transfer rate is large, and the heat loss in the plastic film greenhouse is also large. Therefore, the insulation performance of the polyvinyl chloride film {HotTag} is better than that of the polyethylene film, and the temperature increasing effect is also remarkable. According to tests, the average temperature of the polyethylene film is one to two degrees lower than that of the polyvinyl chloride film.

3. In the PVC film greenhouse, when the water vapor increases, it tends to adhere to the film, forming a fog layer and water oil, causing the sap in the shed. In the polyethylene thin-thickness greenhouse, the situation is much better. Because of its smooth surface, when the water vapor in the shed forms water, it can flow into the soil along the membrane wall.

4. After the polyvinyl chloride film and the polyethylene film are damaged, they can be repaired by heat welding and adhesive. However, the effect of repairing the polyethylene film with an adhesive is worse than repairing the polyvinyl chloride film.

5. Polyethylene films transmit light at a slower rate than polyvinyl chloride films. However, the polyvinyl chloride film is liable to adhere to dust, and it is difficult to wash. After a long period of use, its light transmittance is often inferior to that of a polyethylene film.

6. After the PVC film is washed, if the water stains are not dried or dried, it will be stored in a safe place, and it is easy to form a white water mark on the surface of the film; if it is stacked, if it does not sprinkle some talcum powder, it will be hot. Or if it is stressed, it is easy to stick the films together. Polyethylene film has no such disadvantages, and it is convenient to wash and collect.

7. The polyethylene film has a small specific gravity and is only about 76% of the polyvinyl chloride film. In this way, the area of ​​the land that was originally covered with one hundred kilograms of polyvinyl chloride film was changed to about 80 kilograms.

8. When manufacturing polyvinyl chloride film, the variety and quantity of auxiliary materials used are large, the production process is also more, and the process is difficult to control. The polyethylene film is easy to form and process, and the film with wide width can be produced by blow molding. It can save a lot of labor and time for the splicing film when used.

Drop-free film

The better thermal insulation performance of agricultural plastic film can cause higher ground temperature in the plastic film greenhouse than in the open air. However, in winter and spring, due to the large temperature difference between the inside and outside of the greenhouse, the water vapor in the greenhouse is easy to condense on the inner surface of the greenhouse film. Small mists and fogs, these fog beads will form a water film, and finally gather into small water drops, drop by drop. Polyethylene film condenses water droplets less often, but also forms a layer of fog blocking light. After the film adheres to the fog beads and the water film, it not only affects its light transmission performance, but also hinders the light from entering the greenhouse, and the surface temperature of the shed is lowered due to the absorption of the sun by the water droplets;

In addition, cold water droplets directly fall on the seedlings, and are also prone to rotten, which is unfavorable for the growth of crops. In order to solve this problem, the film manufacturer adds one or more surfactants to the film formulation, so that the surface affinity between the water and the film is greatly reduced or completely eliminated. In this way, the water droplets formed by the water vapor in the greenhouse can be prevented from adhering to the film and flowing down the membrane wall to maintain the original transparency of the film. This surfactant-added plastic film is called a drop-free film. According to tests, the plastic film greenhouse using the drop-free film can increase the temperature by 2-4 degrees compared with the greenhouse using the general film, and the transmittance of ultraviolet light is also increased by one to five percent. Breeding with a non-drip film can make the seedling grow fast, the quality is good, the survival rate is high, and it is not easy to rotten.

However, it is not the seedling cultivation of all crops that uses a drop-free film. For example, rice growing in some areas requires a lower temperature, a shorter time to use the film, and a drop film. At this time, if a drop-free film is used, the amount of light transmitted through the film is large, and the temperature in the greenhouse is too high to scratch the seedling. In addition, when using a drop-free film, attention should also be paid to the temperature change in the greenhouse to enhance management to meet the needs of crop growth.

Colored plastic film

A colored plastic film is a plastic film with various colors. It can also be regarded as a kind of plastic filter that changes the light quality. It can be opaque or transparent. The transparent colored film has a light transmittance of about 80%, mainly red, orange, yellow, green, blue, purple, etc., and the opaque colored film is mainly a black cover film.

The application of colored plastic film in agricultural production in China is not long, but from the test results, it has the effects of increasing crop yield, improving crop quality and reducing plant diseases and insect pests compared with colorless plastic film. For example, the purple film has the effect of improving the yield of spinach, delaying bolting, and prolonging the marketing season. The rice seedlings cultivated with the strong blue film are stronger than those cultivated with the colorless film, the plants are short, the English is more, and the valley is also more Heavier, covered with black film after tobacco colonization, can inhibit weed growth, promote good growth of the seedlings, and so on.

The use of colored plastic film, according to the variety of crops and local natural conditions to choose, for example, yellow film has a significant increase in cucumber production; while the blue film can improve the vitamin C content of Xianglai, but it will make cucumber The yield is reduced. In addition, because the intensity of sunlight is related to the geographical latitude of different regions, the relationship between light quality and light quantity is very complicated, etc., we must use careful research and practice when using colored plastic film, and gain some experience. Then promote it.

The high quality one can be used kill Caligus and sea lice, but no harm for Salmon and water, can used in fresh water and sea water. The low quality one are harm for Salmon, only used to kill fly, ants, cockroach and so on.

The application rate for this use is 0.1 to 0.2 mg/liter as a bath treatment.

The product should be keeped in well-ventilated place and free from exposure on sunshine & raining.