GB1374989A - Surface treating method - Google Patents

Abstract

1374989 Treating surfaces with convertible surfactants PROCTER & GAMBLE Ltd 8 Dec 1971 [8 Dec 1970 12 March 1971 14 May 1971] 57019/71 57020/71 and 14883/71 Divided out of 1344634 and 1370111 Heading D1P [Also in Divisions A5 and C5] A method of treating a surface which has a negative charge when washed comprises (a) wetting the surface with an aqueous solution containing a convertible surface active agent which is able to exist in cationic and non- cationic (i.e. nonionic, anionic or zwitterionic) forms and which has a pKa (defined as being the pH at which 50 mole per cent of the agent is present in cationic form) of 4-9, the solution having a pH below or not more than 2 units above the pKa value of the agent; and (b) subsequently washing the surface with a wash liquor having a pH at least 2 units above the pKa value of the agent. In its cationic form, the agent is substantive to the surface. In its non-cationic form it is non substantive to the surface thus facilitating its removal during step (b). The surface may be a textile (e.g. cotton) and the agent may confer softening, antistatic, soil repellant, soil release, dye transfer resistance and bactericidal properties. The agent may have the formula I: where R<SP>1</SP> is in general a long chain alkyl or alkyl aryl group (up to 26C), R<SP>3</SP> is a short chain alkyl or aryl group (up to 6C), optionally substituted by hydroxy, or cyano, and R<SP>2</SP> may be the same as R<SP>1</SP> or R<SP>3</SP>. X is an anion e.g. halogen or methosulphate and n may be 1-4. Q is an optionally substituted homo- or hetero-cyclic ring having a weakly acidic character. Q may be a phenolic, imidazole or benzimidazole ring. Substituents for Q may be halogen, alkyl or alkoxy (1-6C), nitro, amino, amido, keto, hydroxy or cyano. Other suitable agents include polyoxyalkylene amines, nitrogen ylides as disclosed in Specification 1003926 and 1360233 and quaternary ammonio imides as disclosed in Specification 1359673. Typical compounds are cetylamide trimethylammonium iodide, octadecyl dimethyl-4-hydroxyphenylammonium chloride or iodide, 2-benzimidazolo methyl hexadecyldimethylammonium chloride and 2-benzimidazolo methyl octadecyldimethyl ammonium chloride. The agent may be formulated as a rinse additive composition containing pH buffering agents (e.g. water soluble phosphates, borates, carbonates; citrates or tartrates and their corresponding acids) in such an amount as to generate an aqueous solution having the pH required by step (a) on dilution with tap water or by addition to a rinse solution. Alternatively the agent may be formulated as an alkaline detergent composition containing the usual building salts (e.g. alkali metal phosphates, polyphosphates, carbonates or silicates), chelating agents (e.g. nitriloacetates polycarboxylates, citrates or gluconates), neutral salts (e.g. alkali metal chlorides or sulphates), bleaching agents (e.g. sodium perborate, percarbonates or perphosphates) and non-cationic surface active agents. Suitable non-cationics include anionics when compatible, e.g. alkylaryl sulphonates, alkyl sulphates, and alkyl ether sulphates; nonionics e.g. polyoxyethylene alcohols, alkylphenols, fatty acids and amines, polyethylene oxide-polypropylene oxide condensates and polyoxyethylene sorbitan esters; zwitterionics e.g. quaternary ammonium carboxylates, and sulphonates; and semi-polar nonionic surfactants e.g. tertiary amine oxides and phosphine oxides. The agent, when in cationic form, improves the substantivity of the nonionics and zwitterionics. The agent may be present in an amount of 0.01-5% on the dry weight of the textile. The solution in step (b) for washing the agent off the surface preferably has a pH at least 3 units above the pKa value of the agent, and may be tap water (pH 6.5).