OrganobismuthWith the improvement of people’s awareness of health and environmental protection, the development of non-toxic and environmentally friendly organometallic catalysts It is receiving increasing attention, which mainly includes organic bismuth, zinc, zirconium and other catalysts. Organozirconium metal catalysts have higher catalytic activity towards isocyanate groups and hydroxyl groups.
During the hydrolysis aging process, the residues of different metal ions also have an impact on the hydrolysis resistance of polyester resin. Organobismuth uses different acetylacetone metal compounds as catalysts for the synthesis of polyurethane paint from MDI-polyester. Photoaging studies of the paint film show that Co, Cu, Ti, and Sn all significantly promote aging, while Zn, Ni, and Al have almost no effect.
The fire refining method of crude lead usually consists of the steps of melting and adding sulfur to remove copper, oxidation, refining to remove arsenic and antimony, adding zinc to extract silver, and oxidation, or vacuum zinc removal, adding calcium and magnesium to remove bismuth, etc. Lead and zinc smelters and other plants use this method. Crude lead smelting and sulfur addition to remove copper. The copper content of crude lead is generally 1.2%-2.0%. The smelting method is used to reduce the copper content in the lead.
The fundamental principle of the smelting method is that copper in crude lead can react with arsenic and antimony to form stable refractory compounds – copper arsenide and copper antimonide. These compounds are insoluble in lead and enter the dross and slag in a solid state. Lead parting. The smelting method can reduce the copper in crude lead to less than 0.1%. The equipment used in the melting method includes reverberatory furnaces and melting pots. Large lead smelting plants often use melting pots. The melting pot is made of cast steel, with a capacity of 30-370t, and uses heavy oil as fuel. The melting temperature is 500-600℃, and the melting slag floats out of the lead liquid surface and is fished out with a slag bailer.
Regarding the moisture resistance of HMDI polyurethane membrane, the catalyst used in the synthesis process also has an impact on this. Although aliphatic polyurethane resins of weak solvent systems have been used in China for many years, related problems have still not been solved, and research work is still a hot topic in the industry. The storage stability of polyurethane resin is one of the factors for evaluating the performance of synthetic leather.
Organobismuth T9, Nd, Ce, Bi, Zn, T12 and other catalysts can effectively catalyze the controlled polymerization of aliphatic isocyanates, hydroxyl groups and amine groups in weak solvent systems using TOL, IPA, IBA as solvents. Polyurethane resin with a viscosity of 40~50 Pa·s is produced. Zr has a strong pro-degradation effect, causing the resin viscosity to drop rapidly, while Ni has a strong pro-gelling effect, making the synthesis difficult to control.
