Thermally Expandable Mandrel Sealers

Abstract

It is sometimes advantageous to coat or seal the mandrel before laying on, coating, or wrapping the mandrel with composite plastic material. This invention provides improved coating with improved function that is easily removable from the cured product. The effective coating materials are applied directly to the mandrel as a coat or as a film or tape. Thermally expandable coat or film also reduces manufacturing costs for composite plastic products.

What is claimed: 
     
         1 . (canceled) 
     
     
         2 . (canceled) 
     
     
         3 . The method of manufacturing a composite product comprised of steps:
 a. Coating a mandrel with a thermally expandable coating,   b. Further coating or wrapping said coated mandrel with raw composite plastic,   c. Placing said coated mandrel of step b into a closed external mold, and   d. Heating the resulting assembly of step c above the expansion temperature and curing the composite plastic.   
     
     
         4 . The method of manufacturing a composite product comprised of steps:
 a. Coating a mandrel with a thermally expandable coating or with a pre-fabricated expandable film/tape,   b. Further coating said mandrel with a flexible coating or pre-fabricated film/tape,   c. Coating or wrapping said coated mandrel of step b with raw composite plastic,   d. Placing said coated or wrapped mandrel of step c. into a closed external mold, and   e. Heating the resulting assembly of step d above the expansion temperature and curing the composite material.   
     
     
         5 . The method of  claim 3  wherein said thermally expandable coating contains a thermally expandable material selected from the group: expandable microspheres, thermally expandable graphite. 
     
     
         6 . The method of  claim 5  wherein said thermally expandable material is at a concentration of nearly or about 50 percent. 
     
     
         7 . The method of  claim 3  wherein said thermally expandable coating contains thermally expandable graphite. 
     
     
         8 . The method of  claim 7  wherein said thermally expandable graphite is at a concentration of nearly 50%. 
     
     
         9 . The method of  claim 5  wherein said thermally expandable coating is a prefabricated film/tape. 
     
     
         10 . The method of  claim 6  wherein said said thermally expandable material is in a prefabricated film/tape.