Bismuth isooctanoate
The organic bismuth catalyst is mainly bismuth carboxylate, especially bismuth isooctanoate.
Bismuth isooctanoate, also known as bismuth tris(2-ethylhexanoate).
English name: bismuth octote; bismuth tris (2-ethylhexanoate), etc.
The molecular formula of bismuth isooctanoate is C24H45BiO6, and its molecular weight is 638.6. The CAS number is 67874-71-9 and the EINECS number is 267-499-7.
Structural formula: Bi[OCOCH(C2H5)C4H9]3.
Physical and chemical properties
Brown-yellow viscous liquid, relative density (25℃) is 1.28~1.34, viscosity (25℃) is not more than 3Pa.s.
The bismuth isooctanoate 28% product from the leading American chemical company (The Shepherd Chemical Company) has a bismuth content of 27.7% to 28.3% and non-volatile matter (105℃, 3h) ≧85%.
Organobismuth catalysts from leading U.S. chemical companies are as follows.
Among them, BiCAT 8118 and BiCAT 8108 can be used in almost all kinds of polyurethane materials. BiCAT 8124 is recommended for PU adhesives and elastomers, BiCAT 8106 is recommended for adhesives and sealants, and BiCAT 8210 is recommended for coatings and glues. Adhesive.
The Bi content of the 72% concentration product of bismuth isooctanoate produced by Strem Chemicals, Inc. using mineral spirits as the solvent is about 28%; the 70% to 75% product using xylene as the solvent Concentration product, Bi content is about 24%.
The bismuth isooctanoate from Shenyang Applied Technology Experimental Plant is a yellow-brown liquid with a bismuth content of 4%. Bismuth isooctanoate from another domestic company is a yellow-brown liquid using solvent oil or xylene as a solvent, with a bismuth content of 4%.
Characteristics and uses
Can be used as paint drier, lubricant additive and polyurethane room temperature catalyst. Organobismtium catalysts are environmentally friendly alternatives to toxic heavy metal catalysts such as organic mercury and organic lead. Bismuth isooctanoate has very similar technical properties to organic lead and can be used as a substitute material for lead driers. It has a strong effect on NCO/OH groups. Better selectivity, avoids NCO side reactions, and reduces the generation of CO2; bismuth compounds have better hydrolysis resistance than tin compounds, reducing the selectivity of reactions with water; in aqueous PU dispersions, reducing the interaction between water and NCO groups Side reaction can improve the drying performance of coatings under harsh climate conditions, especially those with high air humidity, and the final product has better mechanical properties; in a one-component polyurethane system, it plays a deblocking role rather than promoting Reaction of NCO with water. However, the catalytic activity is lower 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.
The catalytic effect of bismuth carboxylate on the reaction between aliphatic isocyanate and polyether secondary hydroxyl groups is even better than that of primary hydroxyl groups. Under the catalysis of bismuth carboxylate, polyols containing β-hydroxyalkyl ester, urethane and ether groups , reacts faster with isocyanates than unhindered hydroxyl groups.
The high price of organic bismuth inhibits its widespread application.
