GB1291370A - Corrosion inhibiting cleaner for steel and ferrous metals - Google Patents

Abstract

1291370 Corrosion-inhibiting cleaner STAUFFER CHEMICAL CO 16 Nov 1970 [23 Dec 1969] 54384/70 Headings C7E and C7U A corrosion-inhibiting and passivating metal cleaner comprises a mixture of at least 50 wt per cent alkali metal silicate with an alkali metal nitrate or nitrite. Ortho- or meta-silicates of Na or K and nitrites and nitrates of Na or K are preferably used; Na 2 SiO 3 may be used as a mixture of powder and granules. A chelating agent may be present, such as an aminopolycarboxylic acid or a Na, Li, K, or NH 4 salt thereof, EDTA tetrasodium salt being preferred. A solvent such as a paraffinic or naphthenic mineral oil or ethylene glycol n-hexyl ether may be present, as may a non-ionic or anionic surfactant. Anionic surfactants include higher fatty alcohol sulphates, alkylaryl sulphonates, alkali metal higher alkyl sulpho-succinates, Na N-methyl-N-palmitoyllaurate, Na oleyl isothionate, or alkali metal salts of alkylarylpolyethoxyethanol sulphates or sulphonates. Non-ionic surfactants include alkylphenoxypolyethoxyethanols having C 7-18 alkyl groups and 6-60 or more ethoxy groups, polyethoxyethanol derivatives of methylene-linked alkyl phenols, condensates of 6-60 moles ethylene oxide with mercaptans or alkylthiophenols, ethylene oxide derivatives of long chain carboxylic acids, alcohols, long- or branch-chain amines, or block copolymers of ethylene and propylene oxides, preferred surfactants being low-foaming and bio-degradable, e.g. the linear alcohol ethoxylates. Proportions used may be silicate, 95-50 wt per cent; nitrate or nitrite, 5-50%; chelant, 0-5%; surfactant 0-5%; and solvent 0-5%. 0À25 to 8 ozs. dissolved or dispersed per gallon of water is sprayed on to steel or iron at ambient temperature to 180‹ F. and 10-80 psi, or the metal is dipped therein, to effect cleaning and passivation.