Factors Affecting the Life of Polyurethane Screens
Feb. 21, 2020
Impact of unreasonable use on the life of polyester screen mesh:
After selecting the correct polyurethane screen, it needs to be used reasonably to ensure that the performance of the polyurethane screen is maximized and the life is maximized. However, many users tend to ignore this point when using the polyurethane screen. For example, the tensioned screen is easily loosened by large materials during use, and the tension bolts need to be tightened regularly. If the time is too long, the tension bolts become loose and not tightened, causing a knock between the screen and the support ribs. Affect the life of the screen. At the same time, there is a feed inlet design. It is recommended that the feeding method is not vertical to the screen surface. The feeding direction is oblique along the direction of the logistics.
Polyester bolting cloth supplier believes that the processing technology is the main factor that affects the quality of polyurethane screen materials with the same raw materials.
In view of the complicated working environment, the surface of the metal skeleton must be sandblasted to remove oil and rust stains on the surface, activate the surface, and expand the bonding area. The steel mold is surface-released (coated with a release agent) and then put into a metal skeleton. The platform is heated to 110 ° C and the mold temperature is about 80 ° C.Polyurethane screens should be treated with the appropriate molds and framework before pouring. Regardless of the temperature or the oil stains on the surface of the framework, they should be treated accordingly. If the surface oil stains are not treated properly, it will affect the adhesion between the framework and the polyurethane, and it will easily fall off. Unreasonable, will cause bubbles or burnout during pouring, which will affect the life of the polyurethane screen.
Polyester Screen Mesh
Polyurethane pouring under normal pressure is divided into manual pouring and mechanical pouring. The pouring machine consists of three parts, A, B, and C, which are prepolymer, chain extender, and head respectively. The temperature setting is 85 ° C for A, 115 ° C for B, and 120 ° C for C. The prepolymer and the chain extender are transported to the head system by their respective metering pumps, and the mixing head rotates at high speed without generating air bubbles, and the air in the mixing chamber can be eliminated, and the discharge consumption is less. During the pouring process, the platform of the mold should be maintained at 110 ± 5 ℃. It should not be too high or too low, the mold release agent should not be too much, and the curing time should be greater than 1 hour.
In the process of pouring the polyurethane screen with a pouring machine, the temperature and ratio of the A and B storage tanks must be strictly controlled. The temperature is not easy to be too high or too low, and the ratio must be accurate. Whether it is the pouring temperature or the ratio It directly affects the screen quality and life of polyurethane. The following figure is a quality accident caused by the out-of-scale proportion during pouring.
Molding vulcanization refers to the vulcanization process in the mold before the polyurethane screen is demolded. During the molding vulcanization process, the molding temperature is 100° C to 120° C, and the molding time is 1 to 2 hours.
Maturation refers to the process of heating and vulcanizing the polyurethane screen after demolding, the purpose is to continue the reaction of the isocyanate in the remaining free state and improve the performance of the product. The temperature of the post-curing process is preferably about 115 ° C, and the time is 10 to 14 hours.
In the vulcanization process, time and temperature are critical. If the temperature is too high, it is easy to burn out and the temperature is too low. The reaction is not complete. If the time is too long, the aging of the polyurethane will be accelerated. If the time is too short, the reaction will be incomplete. Whether it is too long or too short, or the temperature is too high or too low, it will directly affect the quality and life of the polyurethane screen. During the processing of the polyurethane screen, the correct polyurethane screen processing technology must be strictly followed to ensure its own quality.
There are many factors that affect the life of polyurethane screens. Whether it is the selection of polyurethane screens, the reasonable use of users, or the processing technology of polyurethane screens, it is indispensable.
When there is no problem in the processing technology of polyurethane screens, only the correct selection and reasonable use of polyurethane screens can maximize the life of polyurethane screens and truly reduce the cost of use and maintenance.