Method of treating a metal substrate
AssigneeXeros Limited
InventorsJohn Edward Steele, Robert Andrew Bird
Life of this patent
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Abstract
A method of cleaning a metal substrate, the method comprising exposing the metal substrate to a body of cleaning liquor comprising a cleaning formulation and a multiplicity of solid particles wherein the method further comprises causing the solid particles and the metal substrate to enter into contacting relative movement; wherein i) the cleaning formulation comprises at least one acid which has a pKa greater than about −1.7; and/or ii) the cleaning formulation comprises at least one base which has a pKb greater than about −1.7; and the length of the particles is from about 0.5 mm to about 6 mm.
Claims79
A method of cleaning a metal substrate, the method comprising exposing the metal substrate to a body of cleaning liquor comprising a cleaning formulation and a multiplicity of solid particles wherein the method further comprises causing the solid particles and the metal substrate to enter into contacting relative movement;
- wherein
- i) the cleaning formulation comprises at least one acid which has a pKa greater than about −1.7;
- and/or
- ii) the cleaning formulation comprises at least one base which has a pKb greater than about −1.7;
- and
- the length of the particles is from about 0.5 mm to about 6 mm.
The method according to any one of the preceding claims wherein the cleaning formulation comprises at least one acid which has a pKa greater than about −1.7.
The method according to any one of the preceding claims wherein the cleaning formulation comprises at least one base which has a pKb greater than about −1.7.
The method according to any one of the preceding claims wherein the cleaning formulation comprises a compound with at least one carboxylic acid moiety.
The method according to any one of the preceding claims wherein the cleaning formulation comprises a compound with two or more carboxylic acid moieties.
The method according to any one of the preceding claims wherein the cleaning formulation comprises a compound containing at least one citrate moiety.
The method according to any one of the preceding claims wherein the cleaning formulation comprises at least one metal chelating agent.
The method according to any one of the preceding claims wherein the cleaning formulation is aqueous.
The method according to any one of the preceding claims wherein the cleaning formulation has a pH between about 1 and about 13.
The method according to any one of the preceding claims wherein the cleaning formulation has a pH greater than about 7.
The method according to any one of the preceding claims wherein at least some of the solid particles are buoyant in the cleaning formulation.
The method according to any one of the preceding claims wherein the solid particles have an average density of less than about 1.
The method according to any one of the preceding claims wherein the solid particles are in the form of beads.
The method according to any one of the preceding claims wherein the method comprises moving the metal substrate such that its surface is brought into contact with the solid particles.
The method according to any one of the preceding claims wherein the method comprises rotating, oscillating or reciprocating the metal substrate within the cleaning liquor.
The method according to any one of the preceding claims wherein the method comprises scouring the surface of the metal substrate with the solid particles.
The method according to any one of the preceding claims wherein the method comprises agitating the solid particles within the cleaning liquor.
The method according to any one of the preceding claims wherein the method is carried out using a fluidized bed containing the cleaning liquor.
The method according to any one of the preceding claims wherein the cleaning liquor contacts the metal surface at a relative velocity of at least 1 cm per second.
The method according to any one of the preceding claims wherein the multiplicity of solid particles comprises or consists of a multiplicity of polymeric particles or wherein the multiplicity of solid particles comprises or consists of a multiplicity of non-polymeric particles.
The method according to any one of the preceding claims wherein the multiplicity of solid particles comprises or consists of a mixture of a multiplicity of polymeric particles and a multiplicity of non-polymeric particles.
The method according to any one of the preceding claims wherein the multiplicity of solid particles comprises or consists of a multiplicity of polymeric particles.
The method according to any one of the preceding claims wherein the solid particles are of hollow and/or porous construction.
The method according to any one of the preceding claims wherein the solid particles are reused one or more times for cleaning of metal substrates according to the method of the invention.
The method according to any one of the preceding claims wherein the method comprises a step of recovering the multiplicity of solid particles after cleaning of the metal substrate.
The method according to any one of the preceding claims wherein the cleaning formulation comprises one or more components selected from the group consisting of:
- solvents, polymers, corrosion inhibitors, builders, chelating agents, surfactants, dispersants, acids, bases, anti-oxidants, reducing agents, oxidising agents and bleaches.
The method according to any one of the preceding claims wherein the method further comprises coating the metal substrate after cleaning the metal substrate.
The method according to any one of the preceding claims wherein the metal substrate comprises a transition metal.
The method according to any one of the preceding claims wherein the metal substrate comprises aluminum.
The method according to any one of the preceding claims wherein the metal substrate is a metal alloy.
The method according to any one of the preceding claims wherein the metal substrate comprises a metal sheet.
The method according any one of the preceding claims wherein the metal substrate is a can.
The method according to any one of the preceding claims wherein the metal substrate is exposed to the cleaning liquor for a period from 1 second to 4 minutes.
A cleaning liquor for cleaning a metal substrate comprising a cleaning formulation and a multiplicity of solid particles wherein the cleaning formulation comprises an acid selected from citric acid, gluconic acid, adipic acid, acetic acid, lactic acid, glycolic acid, oxalic acid, formic acid or the alkali metal salts thereof and wherein the length of the particles is from about 0.5 mm to about 6 mm.
Dependencies are inferred from the claim text.