Method for removing coatings from metal substrates prone to corrosion or deterioration
AssigneeBrent Chemicals International Limited
InventorColin A. Whitton
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Abstract
The invention relates to a method for removing coatings, in particular, organic coatings from metal substrates which are easily corroded or discoloured: aluminimum, aluminium alloy, zinc or zinc alloy. Previously known compositions for this purpose were based on methylene chloride which is environmentally undesirable. In contrast, this invention uses a composition which comprises strong alkali, a polyhydric alcohol or ether derivative thereof and a pyrollidone and/or a lactone. The preferred pyrollidone is N-methyl pyrollidone.
Claims22
A method for removing a coating from a substrate of aluminium, zinc or their alloys comprising contacting the coated substrate comprising zinc, aluminum and/or their alloys with a stripping composition comprising at a temperature no greater than 60.degree. C., the stripping composition comprising a strong alkali;
- a monohydric or polyhydric alcohol or ether derivative thereof;
- and, a 2-pyrrolidone and/or a butyrolactone.
A method according to claim in which the strong alkali is an alkali metal or alkali metal hydroxide.
A method according to any preceding claim in which the alcohol or its derivative has a flash point of at least 90.degree. C.
A method according to claim in which the water content of the composition is no greater than 2% by weight.
A method according to any preceding claim in which the composition additionally comprises a surfactant selected from phosphate esters and polyoxyethylene tridecyl ether phosphate.
Use of a stripping composition comprising a strong alkali, a monohydric or polyhydric alcohol or ether derivative thereof and a 2-pyrrolidone and/or a butyrolactone for removing a coating from a substrate of aluminium, zinc or their alloys at a temperature no greater than 60.degree. C.
Dependencies are inferred from the claim text.