There are three main bonding methods for plastic greenhouse film:
1. Adhesive method. It is mainly used to bond and repair PVC film with vinyl chloride resin plastic adhesive. The polyethylene film can be repaired with polyurethane adhesive, and sometimes it can be ironed with a hot small steel saw blade.
2. Slurry bonding method. During the use of the greenhouse film, if there are small damages such as scraping and wrinkling, cut a piece of plastic, stick mud water and stick it at the damaged place.
3. Thermal bonding method. First, prepare a straight and smooth wooden strip as the backing plate, nail the fine iron window screen, and fix it on the long bench. In order to prevent the plastic from being damaged during soldering, use a plane to flatten the side edges of the wooden strip into a smooth plane. Align one edge of each of the two films to be bonded on the wooden strip, overlapping each other by about 4-5cm. Three to four people operate at the same time. Two people are responsible for "butt sewing" on both sides of the wooden strip. The third person puts a piece of kraft paper or old newspaper strip with a width of 8-10cm and a length of 1.2-1.5m at the aligned film. After covering, use a preheated electric iron along one end of the wooden strip and slowly push it to the other end with appropriate pressure according to experience. The heat, downward pressure and pushing speed of the electric iron used shall be based on the degree that the two films under the paper soften to a certain extent and stick together after being heated. Then remove the paper strip, pull a section of film bonded to the other end of the wood strip, and then bond the next section repeatedly, and repeat until the film is connected to the required length.
Among them, the temperature of the electric iron shall be well controlled when bonding the film. The appropriate temperature for bonding the polyethylene film is 100-110 ℃, and that for PVC is 120-130 ℃. If the temperature is low, it will not stick firmly. Later, it is easy to crack, the temperature is too high, it is easy to melt the film, and holes or thin films will appear at the joints.
The pressure used and the moving speed of the electric iron shall be well matched with the temperature. When the temperature is high, the pressure used shall be small and the moving speed shall be fast. When the temperature is low, the pressure used shall be large and the moving speed shall be slow. When there are oil stains on the pad, it means that the temperature is too high and the plastic has melted. At this time, the paper can not be removed immediately. It should be cooled for a while and then removed when the paper is not hot, so as to better ensure the bonding quality.
When soldering the old film, the film at the joint shall be wiped clean, and the standard of moderate bonding shall be that the newspaper is slightly adhered to the film, otherwise the joint is easy to crack.
