Dissolving gel for cured polysulfide resins
View Patent ↗A cured resin dissolving composition comprising a cellulosic gelling agent prepared in n,n-dimethylacetamide, known for its high penetration and solvency to polar resins, with a glycol-ether co-solvent, 1,8-diazabicyclo(5.4.0)undec-7-ene as a soluble amine, and a surfactant. The mixture of components form a gel-form composition while maintaining high dissolution character for cured polysulfide resins. The optimum thickness of the gel form is dependent upon the amount of the cellulose gelling agent present in the mixture. 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. Once the system has been in contact with the resin and dissolution has been allowed for a period of time, the reacted material may be wiped away or can be easily rinsed with water, an alcohol, or another hydrophilic rinse. The invention has application in a wide range of industries where removal of cured resin is desired either in performing maintenance or for selective cleaning. Examples of industry applications include removing polysulfide coatings and sealants in aerospace, automotive, and construction.
1. A composition effective for dissolving a cured polysulfide resin from vertical and overhead surfaces comprising:
(a) n,n-dimethylacetamide;
(b) a co-solvent that is compatible with the n,n-dimethylacetamide, exhibits dispersion capacity, and contains a minimum amount of alcoholic character needed for enhancing the action of the gelling agent;
(c) 1,8-diazabicyclo(5.4.0)unde-7-ene; and
(d) a gelling agent.
2. The composition of claim 1 which further comprising a compatible surfactant.
3. The composition of claim 1 wherein component (b) is tripropyleneglycol monomethylether (TPM).
4. The composition of claim 1 wherein component (d) is hydroxypropylcellulose.
5. The composition of claim 4 wherein the viscosity of the final product is controlled to 25,000+/−10,000 cps and 50,000+/−20,000 cps, tested at <3 hrs. of preparation and at approximately 72 hrs., respectively.
6. A process for removing cured polymer resin from the surface of vertical or horizontal substrates containing a layer of cured resin with the composition of claims 1 or 4 , allowing sufficient lapse of time to permit the dissolution of the resin and removing the dissolved resin from the substrate by wiping or with a rinse.
7. The process of claim 6 wherein the cured resin to be removed from the substrate is a cured polysulfide.