5-nitrothiazol,-'-06 pesticides such as DDTIOd and Nopcocide,107 and 

 juvenile hormones. lOo Organometallic compounds that have been evaluated 

 as antifoulants include those of mercury, copper, tin, antimony, bismuth, 

 and arsenic . -'-'-'° The development of organomercury and organoarsenic com- 

 pounds is not being pursued due to environmental restrictions, although 

 these compounds are effective antifoulants. "° Patents which cover the use 

 of organotin polymers as antifoulants are limited to those resins which 

 contain an oxygen-tin linkage. Antifouling paints based on organic com- 

 pounds or organometallic monomers are still in the experimental stage; their 

 availability would depend on the success of subsequent coating developments. 



The newly developed organotin-polymer-based coatings are anticipated 

 to have a service life of up to 5 yr. This time may be extended by mechani- 

 cal cleaning. It may be possible to repair and touch up antifouling coat- 

 ings utilizing coatings similar to epoxy paints developed for underwater 

 application. 109 Accordingly, because of the anticipated service life 

 requirement, developmental antifouling coatings are not now judged suitable 

 for providing long-term antifouling protection for the cold water FRP pipe. 



Inherently Antifouling FRP . Inherently antifouling reinforced plastic may 

 be suitable for providing long-term (10- to 15-yr) protection for the OTEC 

 cold water pipe and warm water intake screens. This concept, being devel- 

 oped by the Navy, is based on the synthesis of polyesters and epoxies to 

 which the antifouling tributyltin moieties are chemically attached. Organo- 

 tin is incorporated chemically in the crosslinking agent which is used to 

 cure commercially available unsaturated polyester resins. -'-^^ Organotin 

 epoxies are produced by incorporating the organotin chemically into the 

 epoxy backbone or curing agent .-'--'-*-' The epoxies have been the main approach. 



Glass-reinforced laminates have been fabricated by using organotin 

 polyesters and organotin epoxies. Technical feasibility has been demonstra- 

 ted in the manufacture of inherently antifouling glass-reinforced marine 

 structures (e.g., seawater piping systems and sonar domes). Hand lay-up 

 and vacuum bag techniques were employed to fabricate glass-reinforced 

 laminates using glass cloth. Organotin polyester laminate produced by this 

 method was made of an organotin polyester resin cured at room temperature. 

 Glass-reinforced laminates based on organotin epoxies which incorporate the 



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