Tyzor® Organic Titanates and Zirconate Curing Agents
Tyzor® Titanates and Zirconates are organometallic compounds that offer significant value for the adhesives and sealants industry. They are curing agents that react with polymers that contain hydroxyl or carboxyl groups. This reaction promotes cross-linking of the adhesive and sealant system while increasing the drying rate of solvent-based and water-based systems. Also, when coupled with other cross-linkers, such as organofunctional silanes, Tyzor® improves cross-linking rates in polyurethane and epoxy systems. Tyzor® Titanates and Zirconates do not contain tin or mercury, making them more environmentally responsible curing agents for polyurethane and silicone systems.
More than Just a Curing Agent
In addition to offering control over cure rate, Tyzor® Organic Titanates and Zirconates offer many other benefits when used in adhesive and sealant formulations.
As described previously, Tyzor® cross-links polymers through reaction with hydroxyl and carboxyl functionality. These cross-linked polymers are more durable and resistant to abrasion, chemicals, and moisture. In addition, if Tyzor® is allowed to hydrolyze in air, a protective oxide layer can form on various materials. This can further improve resistance to water, chemicals, alkali, electrical conductivity, and heat for an adhesive or a sealant.
The reactivity of Tyzor® with hydroxyl groups also makes it an outstanding moisture scavenger. When added to moisture-sensitive adhesive and sealant formulations, Tyzor® protects the moisture-sensitive polymers and improves storage stability.
Tyzor® Titanates and Zirconates are also excellent for improving the adhesion of adhesives and sealants to various surfaces, including materials with low surface energy. They can be applied as a primer in a pretreatment step or included in the formulation as an adhesion-promoting additive.
Tyzor® in Silicone Sealants
In moisture-curing RTV-1 silicone sealants, Tyzor® provides valuable functionality as a catalyst for cross-linking between silanes and siloxanes. The previously described moisture-scavenging functionality also helps to prevent premature cross-linking of the silicone sealant. In this application, 1–10 wt% of Tyzor® with respect to the siloxane is typically added. If silanes are used, Tyzor® may be added before or in tandem with them.
Tyzor® in Acrylic Adhesives
Nonaqueous acrylic sealants and adhesives also leverage Tyzor® as cross-linkers. Upon evaporation, cross-linking occurs with carboxylic and hydroxyl groups of copolymerized acrylic acid. For this application, 0.3–1.5 wt% of Tyzor® is added based on the weight of the acrylic polymer used in the system.