Aluminum safe compositions for removing cured polysulfide resins

摘要

A metal-safe dissolving composition for cured resins, comprising a solvent blend that includes a metal safe solvent mixture with addition of a soluble alkali that exhibits a pKa value ≧12. The solvent mixture may include the preferred solvent for metal safety, gamma-butyrolactone (GBL), and the preferred soluble amine, 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU). The solvent, n,n-dimethylacetamide (DMAC) or others, are chosen for high penetration and solvency to polar resins. To this mixture, a surfactant, inhibitor, and cellulose derivative may be added to produce a gel-form property. The product may be used to remove coatings and sealants present on vertical and horizontal surfaces and hard to reach areas commonly encountered when performing maintenance on aviation fuel tanks and similar equipment. Of key importance for the remover is its safety to aluminum and aluminum alloy substrates as demonstrated by modified test methods for sandwich corrosion, for example, ASTM F1110.

主权项

1. A metal-safe composition effective for dissolving a cured polysulfide resin comprising:
(a) a solvent mixture of aprotic solvents selected from the group consisting of n,n-dimethylacetamide, gamma-butyrolactone, n-methylpyrrolidone, n-ethylpyrrolidone, and n-butylpyrrolidone exhibiting a high penetration and solvency capacity for polar resins such as polysulfide; and, (b) a soluble alkali component exhibiting a high pKa value ≧12 and are bicycloorganic bases selected from a group consisting of 1,8-diazabicyclo[5.4.0]undec-7-ene (DABCO), 1,4-diazabicyclo[2.2.2]octane (DBU) and 2,3,4,6,7,8,9,10-Octahydropyrimido(1,2-a)azepine (also DBU) and are present at less than 8% weight concentration; (c) an organosilicon corrosion inhibitor selected from a group consisting of organosilane and organosilicate and are present at less than 5% weight concentration.