Wood Preservation Utilizing Organotin Polymers

The goal of this project is to develop better preservative systems to prevent biodeterioration of wood in marine environments. The utilization of these new preservatives could extend the service life of wood pilings, piers, bulkheading, and fendering systems, thus reducing maintenance and replacement costs. Tributyltin biocides have been chemically linked to monomers which are impregnated in wood and then polymerized "in situ". The resulting wood-polymer matrices slowly release the toxin at a controlled rate. Test coupons treated with tributyltin methacrylate preservative systems have been resistant to biological attack in a semi-tropical marine exposure site for five years to date. Laboratory studies of treatment variables were made. They provided information used to select a basic process for tests to demonstrate industrial feasibility. A model treating system was designed at Washington State University based on current commercial practice in piling treatment plants, but using scaled-down equipment. Small post sections (4 inches in diameter by 3 1/2 feet long) were successfully treated with four different tributyltin methacrylate preservatives. Polymerization in the wood was accomplished by heat cure at moderate temperature (
70-90\deg
C). These post sections are currently being evaluated. This program has effectively demonstrated the feasibility of using tributyltin methacrylate preservative systems, impregnated in wood and polymerized "in situ", for long-term protection of wooden structures in the marine environment.