IE44979B1 - Hair colourant - Google Patents

Abstract

1518874 Dyeing hair with silver salts BEECHAM GROUP Ltd 28 April 1977 [6 April 1976] 13810/76 Heading D1B Keratinous fibres, e.g. human hair are dyed in dark shades by applying evenly to the surface silver acetate, or sulphate in the absence of a reducing agent preferably in solution in water or aqueous alcohol and then exposing the fibres to light and air. The silver salts may be applied in creams, gels or shampoos or sprays containing 0.01 to 2% w/w of the salts.

Description

This invention relates to ia method of darkening the colour of keratinous fibres, especially human hair.

Lead acetate is a commonly used hair dye. Its mechanism of action has not, apparently, been conclusively established, but it is S believed that oxidation of lead acetate on the hair shaft upon exposure to sunlight and the atmosphere leads to the formation of a dark film of lead oxide which is absorbed into the surface of the hair shaft. The action of lead acetate is slow and progressive, gradual darkening of the hair occurring with regular 1° applications according to the concentration applied. Sometimes . colloidal sulphur or sodium thiosulphate is included in lead acetate compositions to modify the darkening effect. In these cases, a dark film of lead sulphide is also believed to be deposited on and absorbed into the hair surface.

The systemic toxicity of lead salts makes their use in the home a.potential hazard to children, and it would be desirable if a less hazardous alternative were available.

An alternative, if less convenient, hair darkening dye system does exist. Aqueous ammoniacal solutions of silver nitrate can Le applied to the hair and developed by the subsequent application of a sulphur compound such as sodium - 2 14970 thiosu.lphate. It is believed that the development process involves the formation of a dark film of silver sulphide whioh is absorbed into the hair surface. Silver salt dye systems proposed in.the past have invariably, so far as S we are aware, required the two stage development process described above, and consequently are generally regarded as less convenient than the one stage application of lead acetate.

This invention is based on the discovery that silver acetate, 10 3ilvsr nitrate and silver sulphate do not require any separate development treatment on the hair shaft but, like lead acetate, will darken the hair when applied as the sole dye component.

Accordingly, the present invention provides a method of i5 darkening the colour of keratinous fibres, particularly human hair, comprising applying silver acetate or silver sulphate or a mixture thereof without a reducing .agent or potential reducing agent substantially evenly to the surface of said fibres, and exposing the thus treated 2q the thus treated fibres to light and air.

Silver acetate, nitrate and sulphate will hereafter be refered to as The Silver Salta.

The silver salts are conveniently applied in the form of a solution in water or aqueous alcohol (the alcohol component preferably being industrial methylated spirit). Since even tiny quantities of the silver salts will have a darkening effect if applied regularly, their fairly low solubilities -3in water (the acetate solubility is reported as 0.72% w/w at 0°C and 2.52% w/w at 80°C) do not present a problem.

Solutions of the silver salts may be applied as such (perfume, colour and other conventional toiletry additives being added if desired) or such solutions may be emulsified into an oil base to produce a cream for application to the hair. Another vehicle for the application of the silver salts would be as an aqueous solution containing a detergent os detergent combination (optionally with perfume, colour, preservative and other common toiletries additives) to provide a shampoo, Still another way of applying the silver salts to the . hair would be as a fine spray,in which case a solution of the silver salts would be packaged in a squeeze pack or in a pressurised can together with a suitable propellant, these packs being equipped with atomizing nozzles. Yet another method of application would be as a foam, dispensed from a pressurised can equipped with an atomising nozzle.

The silver salts might also be applied as a fine suspension in non-aqueous cosmetic bases such as petroleum jelly.

Typically, the silver, salts will be applied to the hair from a solution, suspension, cream, shampoo or spray containing from’ 0.01 to 2% w/w of the salts.

The shade of colouring obtained with the silver salts can be modified by the inclusion of other metal dyes in the application formula. For example copper, nickel or cobalt sulphate could be included -44-4 0 7g It should be noted that the silver salts may stain fabric and therefore should preferably be applied to the hair carefully to avoid splashing, This can be done by using a liquid solution of the 3ilver salts dispensed from a bottle or other container having a sponge applicator pad fixed in the dispensing orifice. Alternatively, a foamed solution of the silver salts could be applied to the hair and rubbed in with the fingers.

Creams and gels would also overcome the problem of splashing 10 and resultant staining, but we find that the silver salts tend to react with the conventional organic components of such cream and gels (and also with some detergents) to cause progressive darkening of the composition upon storage. Although it should be possible to minimise this aesthetic IS problem by careful choice of ingredients, it may be more economical and convenient to apply the silver salts in vehicles which ds not suffer this disadvantage, namely simple aqueous alcoholic solttions.

A further slight inconvenience of these compositions which must be rubbed in with the fingers is the possibility of staining the fingernails, If, as would normally be the case, the user washes his hands within e few minutes of applying the ceapesitions, there will be no fingernail staining problem, but if the silver salts are left in contact with the nails for more than, say, four or five minutes, darkening may occur. _5_ The following Examples illustrate compositions which could be used in the method of this invention :Exampl'e I (Liquid Hair dressing) % w/w Silver Acetate 0.5 Industrial Methylated spirit (IMS) 40.0 Perfume, colour etc. g.s Water to 100.0 Such a composition would be combed or rubbed into the hair, the frequency of application being dependent on the desired rate of darkening. A substantially identical darkening effect is obtained when the silver acetate is replaced by the same quantity Of silver sulphate, or if combinations of silver acetate and/or silver sulphate are used.

Example II (Hair Cream) IS Mineral Oil 40.0 Beeswax , 2.0 Other waxes 2.0 Silver Acetate 0.5 2o Borax/Calcium Hydroxide 0.5 Perfume, colour, preservative q.s Water to 100.0 Such a composition would be combed or rubbed into the hair, the frequency of application being dependent on the desired rate of darkening. A substantially identical darkening effect is obtained when the silver acetate is replaced by -6the same quantity of silver sulphate, or if combinations of silver acetate and/or silver sulphate are used.

NOTEi This cream formulation is prone to progressive darkening upon storage.

Example III Shampoo % w/w Sodium/Ammonium/Triethanolamine/ Monoethanolamine alkyl ether sulphate Coconut Diethanolamide Silver acetate Colour, perfume, preservative Citric Acid Water to 45.0 2.0 0.9 q.s 0.3 100.0 Such a shampoo could be used at intervals, depending on the desired rate of darkening. A substantially indentical / darkening effect is obtained when the silver acetate is replaced by the same quantity of silver sulphate, or if combinations of silver acetate and/or silver sulphate are used.

NOTE; This formulation is prone to progressive darkening upon storage.

Claims (2)

1. CLAIMS:1) A method of darkening the colour of keratinous fibres comprising applying silver acetate, or sulphate or a mixture thereof,', without a reducing agent or 5 potential reducing agent, substantially evenly to the surfaces of said fibres and exposing the thus treated fibres to light and air.

2. ) A method as claimed in Claim 1, wherein said fibres are human hair. 10 3) A method as claimed in Claim 1 or Claim 2, wherein the said silver salts are applied to the fibres as a solution in water or aqueous alcohol.