| Polyurethane sealant is a wide-spread used sealant which exhibit excell-ent flexibility, electricity,anti-corruption and mechanical property.But most of domestic polyurethane sealant are low-grade products which only can be used at construction and domestic industry. Whereas little reseach has been done in the high-grade product such as aerial sealant and primer.The high speed aviation, turning and shake caused by friction in aviation will made the sealant bear continuous and strong load.So it is demanded that the aviation sealant should possess of high cohesion to bear the stress,and good flexibility to absorb the energy of shake.But sealant of this type is poor in adhesion with the substrate,so it is easy to break in the interphase between the metal and the sealant.Therefor,a primer layer should be used to improve the adhesion between the substrate and the sealant.A two component polyurethane sealant and primer were polymerized.The two component polyurethane sealant has excellent flexibility and mechanical property,the primer can enhence the adhesion ability of the sealant greatly. 1. isocyanate and diol which is orderly in molecule-chain was used to polymerize the sealant which exhibit excellent property both in flexibility and tensile strength.2. The influence of molecular weight,cotent of NCO, cotent of carbon, proportion of NCO:OH, removing of bubble and sulfuration was test.And the optimal technics and formula was decided.3. Primer which possess excellent adhesion ability with polyurethane sealant and the substrate was polymerized via the appropriate high-polar copolymer and solvent.4. The base lead chromate enhanced the roughness and surface area of the primer and so improve the adhesion to polyurethane sealant and substrate.5. The excess of NCO can react to the metal substrate,and so enhence the adhesion between the primer and the metal substrate.6. increasing the solvent cotent can better the permeability of the primer,therefor the adhesion with the substrate. |
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