GB921320A - Inhibited single-phase anti-freeze formulations and a method of preparing them - Google Patents

Abstract

An inhibited single-phase anti-freeze composition comprises (a) a glycol, (b) a sodium borate, (c) sodium metasilicate, and (d) water; the composition preferably also includes (e) a compound of the formula <FORM:0921320/III/1> wherein R and R11 are hydrogen, alkyl or substituted alkyl, R1 is alkyl or substituted alkyl, alkoxy or substituted alkoxy, x is 0-2 and y is 2-x, and (f) sodium mercaptobenzothiazole. (a) is preferably ethylene glycol, but may also be glycerol, or propylene or diethylene glycol; (b) is suitably borax or a mixture comprising 30-10% borax and 70-90% sodium metaborate; and (e) is invariably tributoxyethyl phosphate. In general (b) comprises by weight 2-3, preferably 2,5-2,75, parts of borax, or 1-3,5, preferably 1,5-3, parts of the borax/metaborate mixture; (c) comprises 0,01-0,3, preferably 0,2, parts; (e) comprises 0,01-2, preferably 0,05-0,15, parts; (f) comprises 0,005-0,5, preferably 0,01, parts; water (d) from all sources (including water of hydration) comprises 1-5, preferably 1,5-5, parts; and glycol (a) preferably comprises 95 parts. Usually water (d) (including water of hydration) comprises at least 3 times as many parts as silicate (c). The formulation is achieved by dissolving borate (b) in a water-glycol mixture, adding additional glycol, separately dissolving the metasilicate (c) in water, and then adding the solution to the water-glycol mixture with vigorous agitation, (f) being added during the sequence of operations. If the presence of metaborate is required it may be formed in situ by adding sodium hydroxide to the tetraborate to adjust the pH to 6,5-11, preferably 7,5-8,5. The invention also embraces an additive for glycolic anti-freezes which comprises sodium borate, sodium metasilicate and mercaptobenzothiazole.