Alkaline degreasing solution
AssigneeNippon Paint Co., Ltd.
InventorsTamotsu Sobata, Naohiko Sumie
Life of this patent
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Abstract
An alkaline degreasing aqueous solution containing 0.01 to 10 g/l of a nonionic surface-active agent, and an organic substance exhibiting water solubility or water dispersibility at a pH value of at least 8, having a phenolic hydroxyl group with a molecular weight of at least 500, at a weight ratio of 0.1 to 2:1=(organic substance having a phenolic hydroxyl group):(nonionic surface-active agent). The alkaline degreasing aqueous solution has a pH value of at least 8.
Claims8
An alkaline degreasing aqueous solution comprising 0.01-10 g/l of a nonionic surface-active agent, and an organic substance exhibiting water solubility or water dispersibility at a pH value of at least 8, having a phenolic hydroxyl group with a molecular weight of at least 500, at a weight ratio of 0.1 to 2:1=(organic substance having a phenolic hydroxyl group):(nonionic surface-active agent), said alkaline degreasing solution having a pH value of at least 8, said organic substance being a condensate of formaldehyde and sodium salt of bis(hydroxyphenyl)sulfonemonomethylsulfonic acid.
A method for treating a waste water alkaline degreasing solution which has been used to degrease a metal surface and comprises 0.01-10 g/l of a nonionic surface-active agent, and an organic substance exhibiting water solubility or water dispersibility at a pH value of at least 8, having a phenolic hydroxyl group with a molecular weight of at least 500, at a weight ratio of 0.1 to 2:1=(organic substance having a phenolic hydroxyl group):(nonionic surface-active agent), said alkaline degreasing solution having a pH value of at least 8, said organic substance being a condensate of formaldehyde and sodium salt of bis(hydroxyphenyl)sulfonemonomethylsulfonic acid, by the step comprising:
- adjusting a pH value of said alkaline degreasing aqueous solution to a pH of less than 8, wherein said nonionic surface-active agent is reacted with said organic substance in said waste water of said alkaline degreasing aqueous solution, thereby facilitating sedimentation of said nonionic surface-active agent and said organic substance.
Dependencies are inferred from the claim text.