Methods for cleaning materials
AssigneeUnion Oil Company of California
InventorDonald C. Young
Life of this patent
Estimating the term…
Abstract
Acid-reactive organic and inorganic matter, such as stains and/or deposits, is removed from substrates by contacting such matter with a composition containing urea and sulfuric acid in which the urea/sulfuric acid molar ratio is less than 2. The urea-sulfuric acid compositions may optionally contain other components such as water, surfactants, and/or non-aqueous polar solvents which accentuate the activity of the compositions toward hydrophobic materials. The water-containing compositions which have H.sub.2 O/(urea+H.sub.2 SO.sub.4) molar ratios below about 2.5 are particularly useful for removing hydrolyzable matter by partial or complete hydroylsis.
Claims47
A method for removing matter from a substrate, which method comprises the step of contacting said matter with a composition comprising urea and sulfuric acid in which the urea/sulfuric acid molar ratio is within the range of about 1/2 to less than 2, and said urea and sulfuric acid, in combination, comprise at least about 30 weight percent of said composition.
A method for removing matter from a substrate, which method comprises the step of contacting said matter with a composition comprising urea and sulfuric acid in which the urea/sulfuric acid molar ratio is about 1/1 to about 3/2, said urea and sulfuric acid, in combination, constitute at least about 30 weight percent of said composition, and said matter is selected from the group consisting of organic and inorganic stains, dyes and pigments, resins, algae, molds, proteinaceous matter, cellulosic matter, metal sulfides, oxides, hydroxides, carbonates, thiocarbonates, and simple and complex metal salts, and combinations thereof.
A method for removing acid-hydrolyzable matter from a substrate, which method comprises the step of contacting said acid-hydrolyzable matter with a composition comprising urea, sulfuric acid, and water, in which the urea/sulfuric acid molar ratio is within the range of about 1/1 to about 3/2, and wherein the H.sub.2 O/urea+H.sub.2 SO.sub.4) molar ratio in said composition is less than about 2.5.
A method for removing matter from a metal surface, which method comprises the step of contacting said matter with a composition comprising urea and sulfuric acid in which the urea/sulfuric acid molar ratio is within the range of about 1/2 to about 3/2, said urea and sulfuric acid, in combination, constitute at least about 30 weight percent of said composition, and said matter is selected from the group consisting of metal sulfides, oxides, hydroxides, carbonates, thiocarbonates, and simple and complex metal salts, and combinations thereof.
A method for removing a resinous deposit from a metal surface, which method comprises the step of contacting said deposite with a composition comprising urea and sulfuric acid in which the urea/sulfuric acid molar ratio is within the range of about 1/2 to about 3.2, and said urea and sulfuric acid, in combination, constitute at least about 30 weight percent of said composition.
A method for removing a deposit from the interior of fluid heat exchange equipment, which method comprises the step of contacting said deposit with a composition comprising urea and sulfuric acid in which the urea/sulfuric acid molar ratio is within the range of about 1/2 to about 3/2, and said urea and sulfuric acid, in combination, constitute at least about 30 weight percent of said composition.
A method for removing matter from a surface which method comprises the step of contacting said matter with a composition comprising urea and sulfuric acid wherein said urea and sulfuric acid, in combination, constitute at least about 60 weight percent of said composition, and the molar ratio of urea to sulfuric acid is within the range of about 1/1 to about 3/2.
Dependencies are inferred from the claim text.