Bismuth isooctanoate
Organic bismuth catalysts are dominated by bismuth carboxylate, especially bismuth isooctanoate.
Bismuth isooctanoate, alias tris(2-ethylhexanoate) bismuth.
English name: bismuth octote; bismuth tris(2-ethylhexanoate), etc.
The molecular formula of bismuth isooctanoate is C24H45BiO6, molecular weight is 638.6. CAS number is 67874-71-9, EINECS number is 267-499-7.
Structural formula: Bi[OCOCH(C2H5)C4H9]3.
Physical and chemical properties
Brownish yellow viscous liquid, relative density (25℃) is 1.28~1.34, viscosity (25℃) is not more than 3Pa.s.
The Shepherd Chemical Company’s bismuth isooctanoate 28% product, the amount of bismuth content of 27.7% ~ 28.3%, non-volatile fraction (105 ℃, 3h) ≧ 85%.
The organic bismuth catalysts of The Shepherd Chemical Company (USA) are as follows.
Among them, BiCAT 8118 and BiCAT 8108 can be used for almost all kinds of polyurethane materials, BiCAT 8124 is recommended for PU adhesives and elastomers, BiCAT 8106 is recommended for adhesives and sealants, BiCAT 8210 is recommended for coatings and adhesives.
The Bi content of the 72% concentration of bismuth isooctanoate produced by Strem Chemicals, Inc. with solvent oil as solvent is about 28%; the Bi content of the 70%-75% concentration of products with xylene as solvent is about 24%.
The bismuth isooctanoate of Shenyang Applied Technology Experimental Factory is yellow-brown liquid with 4% bismuth content. The bismuth isooctanoate of another domestic company is yellow-brown liquid with solvent oil or xylene as solvent, and the bismuth content is 4%.
Characteristics
and usageIt can be used as paint catalyst, lubricant additive and polyurethane room temperature catalyst. Organic bismuth catalyst is an environmentally friendly substitute for organic mercury, organic lead and other toxic heavy metal type catalysts, bismuth isooctanoate has very similar technical properties with organic lead, can be used as a substitute material for lead catalyst, better selectivity for NCO/OH group, avoid NCO side reaction, reduce CO2 generation; bismuth compound has better hydrolysis resistance stability than tin compound, reduce the selectivity of reaction with water; in water-based PU dispersions, reduce the side reaction between water and NCO groups, can improve the drying performance of coatings under harsh climatic conditions, especially under the harsh conditions of high air humidity, and make better mechanical properties of the final product; in one-component polyurethane systems, play a role in unblocking, rather than promoting the reaction between NCO and water. However, the catalytic activity is low in some systems. The combination of bismuth and zinc has a synergistic effect, making formulation and production more flexible. It can be used alone, or in combination with amines or other organometallic compounds.
Bismuth carboxylate catalyzes the reaction of aliphatic isocyanates with polyether secondary hydroxyl groups even better than primary hydroxyl groups, and polyols containing β-hydroxyalkyl esters, carbamates and ether groups react with isocyanates at a faster rate than non-site blocking hydroxyl groups under the catalysis of bismuth carboxylate.
The high price of organic bismuth inhibits its wide application.Translated with www.DeepL.com/Translator (free version)
