Abstract A coating which is both a flexible sealant and a corrosion-inhibitive primer which can be used to protect the exterior skin and fastener patterns of high performance aircraft at low temperatures. The coating includes corrosion inhibitive pigmentation, resins, a curing agent, and a solvent blend permitting spray application of the coating. The two resins included in the coating are a reaction product of an epichlorohydrin and bisphenol A plus a polyurethane elastomer which is a reaction product of an aromatic isocyanate and a polyether glycol. The curing agent is a blocked diamine, i.e., a ketimine. The ketimine can be prepared by reacting a carbonyl compound and an aromatic diamine. Water is produced in this reaction. The reaction is reversible, so that as the ketimine absorbs atmospheric moisture, the aromatic diamine is released and in turn cures or cross-links the resins. The mixture of pigmentation, resins, ketimine, and solvent blend is a sprayable material that can be readily applied to surfaces using conventional spray equipment. After application, as the diamine is released, the coating is cured to a tough weather-resistant film. When utilized to protect exterior surfaces, a durable exterior coating can then be applied over the flexible sealant-primer to obtain a two-coat, all weather protective paint system.
A method for preparing a protective coating composition, comprising: forming a first component by mixing, in parts by weight, ______________________________________
epoxy resin having an epoxide equivalent
between 185 and 196, viscosity between
110 and 160 poises, and density between
9.6 and 9.8 lbs./gal. at 68° F
291
strontium chromate 1701
titanium dioxide 319
magnesium silicate 788
diatomaceous silica 414
leveling agent 135
methyl n-butyl ketone, urethane grade
3386
______________________________________ forming a second component by mixing, in parts by weight, ______________________________________
ketimine curing agent 1680
methyl ethyl ketone, urethane grade
2754
______________________________________ forming a third component by mixing, in parts by weight, ______________________________________
aromatic polyurethane resin having a 100% modulus
of 400 psi at 100° C and an available isocyanate
content of 2.8% 1740
polyurethane resin having a 100% modulus of
1100 psi at 100° C and an available isocyanate
content of 4.1% 873
xylene, urethane grade 1214
butyl acetate, urethane grade
699
toluene, urethane grade 634
______________________________________ wherein said polyurethane resins are selected from the group consisting of a compound having the formula ##STR8## and a compound having the formula ##STR9## and combining said first, second and third components in equal parts by volume.
Claim 2
Independent Claim
194 words
A method for preparing a protective coating composition, comprising: forming a first component by mixing, in parts by weight, ______________________________________
epoxy resin having an epoxide equivalent
between 185 and 196, viscosity between
110 and 160 poises, and density between
9.6 and 9.8 lbs./gal. at 68° F
291
strontium chromate 1701
titanium dioxide 319
magnesium silicate 788
diatomaceous silica 414
leveling agent 135
methyl n-butyl ketone, urethane grade
3386
______________________________________ forming a second component by mixing, in parts by weight, ______________________________________
ketimine curing agent 1680
methyl ethyl ketone, urethane grade
2754
______________________________________ forming a third component by mixing, in parts by weight, ______________________________________
aromatic polyurethane resin having a 100% modulus
of 400 psi at 100° C and an available isocyanate
content of 2.8% 1740
polyurethane resin having a 100% modulus of
1100 psi at 100° C and an available isocyanate
content of 4.1% 873
xylene, urethane grade 1214
butyl acetate, urethane grade
699
toluene, urethane grade 634
______________________________________ wherein said polyurethane resins are selected from the group consisting of a compound having the formula ##STR8## and a compound having the formula ##STR9## and combining said first, second and third components in equal parts by volume.