Cleaning of hard surfaces

• US 4,082,683 A
• Filed: 09/10/1976
• Issued: 04/04/1978
• Est. Priority Date: 09/19/1975
• Status: Expired due to Term

• Current Assignee: Lever Brothers Company (Unilever PLC)
• Original Assignee: Lever Brothers Company (Unilever PLC)
• Inventors: Galesloot, Wilhelmus Gerardus
• Primary Examiner(s): Weinblatt, Mayer
• Application Number:
  US05/722,254
• Time in Patent Office: 571 Days
• Field of Search: 252/105, 252/188, 252/81, 252/178
• US Class Current: 510/367
• CPC Class Codes: C11D 3/0042 Reducing agents
• CPC Class Codes: C23G 1/24 with neutral solutions

Abstract

An improved dithionite composition suitable for preparing stock solutions comprising a dithionite, e.g., sodium dithionite, and at least 5% by weight of a water-soluble sulphite, e.g., sodium sulphite. The composition may further contain a metal-complexing agent, an activator for the dithionite, a surface-active agent and a thickening agent. The composition is applicable for the removal of metal dust soiling and metal oxide stains, particularly rust stains, from surfaces.

Claims

1. A dithionite composition which upon admixture with water forms a solution of pH 5 to 9 consisting essentially of:

a. 20-60% by weight of a dithionite selected from the group consisting of alkali metal dithionites and zinc dithionites;

b. 10-50% by weight of a water soluble sulfite selected from the group consisting of alkali metal sulfites and ammonium sulfite;

c. 5-30% by weight of a metal-complexing agent selected from the group consisting of nitrilotriacetic acid;

the alkali metal salts of nitrilotriacetic acid, ethylene diamine tetraacetic acid;

the alkali metal salts of ethylene diamine tetraacetic acid;

citric acid;

the alkali metal salts of citric acid;

gluconic acid;

the alkali metal salts of gluconic acid;

d. 0.3-5% by weight of an activator for said dithionite, wherein said activator is selected from the group consisting of OH^-, Cl^-, Br^- or NO^-₂ substituted benzoquinone;

OH^-, Cl^-, Br^- or NO^-₂ substituted naphthoquinone, and SO₃ H^- or OH^- substituted anthraquinone;

e. 1-15% by weight of a thickening agent in an amount sufficient to result in said composition having a viscosity of about 20 to about 100 centipoises when admixed with water, said thickening agent being selected from the group consisting of derivatives of polysaccharides and hydroxyethylcellulose; and

f. optionally 0-10% by weight of an anionic or nonionic organic surface active agent, and 0-40% by weight of sodium sulfate.

2. A dithionite composition as claimed in claim 1, in which the dithionite is sodium dithionite and the water-soluble sulphite is sodium sulphite.

3. A dithionite composition as claimed in claim 1, the solution of which has a pH within the range of 6 to 8 and a viscosity of 30 cps to 80 cps.

4. A dithionite composition as claimed in claim 1, which incorporates an SO₃ H-- or OH-substituted anthraquinone.