| 摘要 |
A composition which forms an aqueous emulsion suitable for degreasing metal surfaces comprises (1) one or more organic solvents for grease, (2) a keto-alcohol, (3) at least one non-ionic emulsifying agent, and (4) at least one anionic emulsifying agent; the composition must also include an unsaponifiable oil, unless the organic solvent for grease is itself such an oil. For cleaning rusty metal surfaces the composition may be emulsified in a dilute mineral acid, which may be sulphuric acid, if the metal is later to be given a phosphatic coating, or may be phosphoric and (or) chromic acid, if the metal surface is to be passivated. The organic solvent may be a mineral oil fraction, and the keto-alcohol may be diacetone alcohol. The non-ionic emulsifying agent may be a reaction product of ethylene oxide with a higher aliphatic alcohol or with a primary or secondary amine containing a radical of at least eight carbon atoms. The anionic emulsifying agent may be a sulphonamido acetic acid, e.g. a compound of the formula RSO2NHCH2COOH, where R is a radical of at least 8 carbon atoms. In use, the metal surface may be treated first with an emulsion as above at pH 7-9 to remove grease and then with a second emulsion at pH 0.5-2 to remove rust; treatment in turn with water and a phosphating or a passivating solution may follow. Alternatively, the surface may be derusted and descaled by treatment with a 25 per cent mineral acid solution and then treated with the emulsion without rinsing, or it may be treated in turn with an emulsion at pH 0.5-2 and then with water and a phosphating or a passivating solution. The emulsions are resistant to frothing and may be applied by spraying, suitably at 50-80 DEG C. Examples of suitable compositions are given.ALSO:A composition which forms an aqueous emulsion suitable for degreasing metal surfaces comprises (1) one or more organic solvents for grease, (2) a keto-alcohol, (3) at least one non-ionic emulsifying agent, and (4) at least one anionic emulsifying agent; the composition must also include an unsaponifiable oil, unless the organic solvent for grease is itself such an oil. For cleaning rusty metal surfaces the composition may be emulsified in a dilute mineral acid, which may be sulphuric acid, if the metal is later to be given a phosphatic coating, or may be phosphoric and (or) chromic acid, if the metal surface is to be passivated. The organic solvent may be a mineral oil fraction, and the keto-alcohol may be diacetone alcohol. The non-ionic emulsifying agent may be a reaction product of ethylene oxide with a higher aliphatic alcohol or with a primary or secondary amine containing a radical of at least eight carbon atoms. The anionic emulsifying agent may be a sulphonamido acetic acid, e.g. a compound of the formula RSO2NHCH2COOH, where R is a radical of at least 8 carbon atoms. In use, the metal surface may be treated first with an emulsion as above at pH 7-9 to remove grease and then with a second emulsion at pH 0.5-2 to remove rust; treatment in turn with water and a phosphating or a passivating solution may follow. Alternatively, the surface may be derusted and descaled by treatment with a 25 per cent mineral acid solution and then treated with the emulsion without rinsing, or it may be treated in turn with an emulsion at pH 0.5-2 and then with water and a phosphating or a passivating solution. The emulsions are resistant to frothing and may be applied by spraying, suitably at 50-80 DEG C. Examples of suitable compositions are given. |
