Production Technology of Polyurethane Strip Sieve
1. synthesis of prepolymers① Raw materials, oligomer polyols: ODX2218, CMA21024; polytetramethylene glycol (PTMG1000), and dehydration treatment should be done before use, so that water content is less than 0.05%. Polyisocyanate: toluene diisocyanate (TDI2100).
② The synthesis of prepolymer lowers the temperature of dehydrated oligomer polyols to 40 ~60 ℃, adds them to the reactor, stirs continuously and adds metered toluene diisocyanate. After 30 to 40 minutes, the reaction is slowly heated to (80) ℃, and continues for 2 to 3 hours. Sampling analysis - 5NCO%, reaching 4.0%-5.0%, and prepolymer was obtained by vacuum defoaming at 0.8kPa for 30 minutes.
① Pretreatment of metal skeleton In order to ensure the rigidity of polyurethane strip sieve in use, the metal skeleton is usually lined with steel skeleton. The steel skeleton of the medium and small sieve plate is mostly welded frame structure, while the tension sieve plate is mostly made of multiple strands of wire rope. In view of the complex working environment, the metal skeleton surface must be sandblasted to remove oil stains, rust stains, activate the surface and expand the bonding area.
2. Casting Technology
② After surface demoulding treatment, the assembly steel die of the die is put into the skeleton, and the temperature of the platform rises to 110 ℃.