CLIAMS:WE CLAIM:

1. Hair colouring kit for generating a tannin-iron complex imparting stable wash proof colour on the hair comprising
a. a tannin source in the levels of 5-25% wt./v as a water based hair colour active combination;
b. ferrous ammonium sulphate in the levels of 5-25% wt./v as a water based hair colour active combination;
c. potassium carbonate as pH modifier to favour generating the pH range of said formulation of 7-9 for ionization of tannin and/ or altering the degree of dissociation of ferrous ammonium sulphate to favour intense colour shades of brown to black with low RGB values of 30 to 40 ; and
d. instructions for sequential addition of the tannin, ferrous ammonium sulphate and potassium carbonate for achieving said tannin-iron complex imparting stable wash proof colour on the hair preferably maintaining tannin : ferrous ammonium sulphate as hair colouring actives in the range of 1 to 5 : 5 to 1 preferably 1 : 1.
2. Hair colouring kit as claimed in claim 1 which is suitable for preparation of water based pH dependent brown coloured hair with said tannin source application providing altered pH of 7-9 from 3 followed by application of ferrous ammonium sulphate.
3. Hair colouring kit as claimed in claim 1 which is suitable for preparation of water based pH dependent black coloured hair with said application of tannin source followed by ferrous ammonium sulphate with altered pH of 9 from 6.
4. A method of colouring the hair comprising sequentially applying the pH dependent hair colour ingredients on hair selected from
a. tannin in the levels of 5-25% wt./v as a water based hair colour active combination;
b. ferrous ammonium sulphate in the levels of 5-25% wt./v as a water based hair colour active combination;
c. potassium carbonate as pH modifier to favour generating the pH range of said formulation of 7-9 for ionization of tannin and/ or altering the degree of dissociation of ferrous ammonium sulphate to favour intense colour shades of brown to black with low RGB values of 30 to 40
maintaining tannin : ferrous ammonium sulphate as hair colouring actives in the range of 1 to 5 : 5 to 1 preferably 1 : 1.
5. A method as claimed in claim 4 wherein said sequential application of the pH dependent hair colour ingredients on hair involve water based colouring of hair following the sequence of:
a. providing tannin source solution on hair by changing the pH from 3 to 7-9 by potassium carbonate;
b. providing solution of ferrous ammonium sulphate thereafter involving total application time 1 to 60 mins at room temperature to obtain brown coloured hair therefrom which is free of any required intermediate washing between said application in step a) and step b).
6. A method as claimed in claim 4 wherein said sequential application of the pH dependent hair colour ingredients on hair involve a water base colouring of hair following the sequence of : a. providing tannin solution on hair;
b. providing solution of ferrous ammonium sulphate by changing the pH from 6 to 8 by potassium carbonate thereafter involving total application time of 1to 60 mins at room temperature to obtain black coloured hair therefrom which is free of any required intermediate washing between said application in step a) and step b).
7. A method as claimed in anyone of claims 4-6 optionally involving the steps of
i. carrying out said colouring of the hair in the range of 40-75 °C for 1to 15 mins to favour hair colouring in desired intense colour shades with very low RGB values of 30to 40 under reduced concentration of the ingredients in the range of 5-10% w/v; with or without further step of
ii. applying sonication treatment to the hair for1to 15 mins to favour colouring of the hair in desired colour shades under reduced concentration of the ingredients in the range of 0.1-5 % w/v.
8. A method of colouring the hair as claimed in anyone of claims 4-7 involving tannin-iron complex imparting stable wash proof colour on the hair free of any p-PDA based ingredients and toxic ingredients.

Dated this the 15th day of June, 2015 Anjan Sen
Of Anjan Sen and Associates
(Applicants Agent)

,TagSPECI:FIELD OF THE INVENTION
The present invention provides for a hair colouring formulation/kit for generating tannin-iron complex based stable wash proof hair colour that is pH dependent. More particularly, the present invention provides for a method of colouring the hair comprising sequentially applying the pH dependent hair colouring ingredients selected from tannin source, ferrous ammonium sulphate and potassium carbonate as pH modifier, affecting the degree of dissociation of said ferrous ammonium sulphate and ionization of tannin thereby influencing the activity, all in selective amounts and in simple water base to enable colouration of the hair in darker colour shades free of any additional ingredients and any additional intermediate washing of hair while application of the selective ingredients.
BACKGROUND ART
Tannin-Iron complex method is one of the widely studied processes for colouring hair using non p-PDA method. This process could not be successfully commercialized owing to few shortcomings like high concentration of precursors, longer duration of colouring, less intensity of colouring etc.
US20110253163 teaches a method of colouring keratinous fibres comprising contacting the keratinous fibres sequentially with a pre-treatment composition and a colour developer selected from one or more of hydrolysable tannin or its breakdown products or derivatives or a mixture thereof obtained from a natural or synthetic source and wherein the pre-treatment composition comprises: iron salt including reducing agent selected from one or more of sodium sulphite, sodium metabisulphite, sodium thiosulphate, sodium dithionite or a mixture thereof and a penetration enhancer e.g. methanol, ethanol, propanol, butanol or their isomers; vicinal diols such as ethylene or propylene glycols. This prior art method of colouring the hair for improving the hair colour involves use of additional penetration enhancing agents.
US4946472 discloses a hair-dyeing composition comprising geraniintannin and a water-soluble iron salt and comprises additionally one or more compounds selected from tannic acid, L-cysteine and salts thereof, sodium hydrogen sulfite, sodium sulfite, hydrolyzed product of collagen and resins for hair. This prior patent also uses reducing agents and penetration enhancers such as propylene glycol and ethanol, in which glycol acts as penetration enhancer and further involves drying of hair in-between two applications making it cumbersome and lengthy process for the consumers.
EP0327345 is directed to a composition for darkening hair comprising (i) a first component, which comprises a shampoo detergent base and at least one metal salt; and
(ii) a second component, which comprises at least one organic compound selected from the group comprising catechol, pyrogallol, gallic acid or an ester thereof or tannic acid or a mixture thereof, aromatic amines and precursors of melanin which, in use, changes colour as a consequence of the formation of a dark-coloured complex when mixed with the said metal ion, and a base suitable for use as a hair shampoo, conditioner, tonic, cream, styling gel or mousse; wherein the metal salt is iron (II) salt that is iron (II) ammonium sulphate. This prior art involves the use of a detergent base including ethanolamine salts to get the desired colouring effect on hair in the presence of iron (II) ammonium sulphate.
US8313537 teaches a mordant useful in a dyeing hair product, comprising an effective amount of a ferrous salt and an antioxidant wherein the antioxidant is ascorbic acid or salts thereof, cysteine or derivatives thereof or salts thereof, a reduced glutathione, or a combination thereof. This prior art also teaches a hair dyeing product, comprising a softening agent, a dyeing composition, wherein the dyeing composition comprises a dyeing agent and said mordant wherein said dyeing agent is gallic acid, or salts or esters thereof, or a combination thereof.
The hair dyeing product of this prior art involves i) the disulfide bond reducing agent that is cysteine or derivatives thereof or their salts, acetylcysteine or derivatives thereof or their salts, a sulfite, or a bisulfite, or any combination thereof and ii) the alkalizing agent that is ornithine, arginine, lysine, ammonia, an ethanolamine, an alkanolamide, or a composition comprising a carbonate, or any combination thereof. This prior art thus uses disulphide bond reducing agents and also involves the use of softening agents prior to treatment with colouring agent which is considered to be disadvantageous from consumer standpoint.
CN102166173 teaches ecological hair dyes comprising tannic acid together with a ferrous salt with sodium carbonate, potassium hydroxide or sodium hydroxide to adjust the pH of a colouring agent. This prior art patent teaches about hair colour prepared using mixture of tannin and radix isatis with iron salts and includes additives like sodium sulfite and cysteine sulfhydryl in the hair colour formulation.
WO2013064598A teaches use of polyphenol and iron salt in different formulations for dyeing hair. The hair colour intensity obtained via this method is not reported. Further, products with few iron salts like chloride and sulphate are reported to be unstable, thereby reducing the opportunity to utilize widely available cheap ingredients.
It is apparent from the state of the art that while there are several patents dealing with the compositions, methods/ processes for colouring the hair involving tannin, but the same is found to involve various reducing agents, penetration enhancers such as glycols, additional p-PDA, use of a detergent base, additional softening agents before application of colouring agent which is disadvantageous in involving additional ingredients in the formulation that also sometimes require drying of hair in between two applications making it cumbersome for the users and involves lengthy application time.
Therefore, there is a need in the art to explore for formulation and a viable process thereof involving said formulation that would address the above said shortcomings to make the process of hair colouration easier to thus save application time devoid of any additional ingredients.
OBJECTS OF THE INVENTION
It is thus the primary object of the present invention to provide for a hair colouring formulation/ kit and a method thereof for colouring the hair that would provide permanent black hair colour on the hair free of p-PDA which would be easy to use, non toxic and would not cause any damage to the hair.
It is another object of the present invention to provide for said method of colouring the hair involving hair colouring formulation/ composition that would provide a stable wash proof colour to the hair in the absence of any penetration enhancers in simple water base free of any softening agents, to be economically viable and would be user friendly.
It is yet another object of the present invention to provide for said hair colouring formulation/ kit applicable at room temperature/ moderately high temperature involving few simple convenient steps free of any drying steps in-between two applications to thus save on the application time.
It is another object of the present invention to provide for said hair colouring formulation/kit with lower RGB (30 to 40) values indicating higher colour intensity than any other Fe-metal based hair colour.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided a hair colouring formulation/ kit for generating a tannin-iron complex imparting stable wash proof colour on the hair comprising
a. a tannin source in the levels of 5-25 % wt./v as a water based hair colour active combination;
b. ferrous ammonium sulphate in the levels of 5-25 % wt./v as a water based hair colour active combination;
c. potassium carbonate as pH modifier to favour generating the pH range of said formulation of 7-9 for ionization of tannin and/ or altering the degree of dissociation of ferrous ammonium sulphate to favour intense colour shades of brown to black with low RGB values of 30 to 40; and
d. instructions for sequential addition of the tannin, ferrous ammonium sulphate and potassium carbonate for achieving said tannin-iron complex imparting stable wash proof colour on the hair preferably maintaining tannin : ferrous ammonium sulphate as hair colouring actives in the range of 1 to 5 : 5 to 1 preferably 1 : 1.
According to another preferred aspect of the present invention there is provided said hair colouring formulation/ kit which is suitable for preparation of water based pH dependent brown coloured hair with said tannin source application providing altered pH of 7-9 from 3 followed by application of ferrous ammonium sulphate.
According to yet another preferred aspect of the present invention there is provided said hair colouring kit which is suitable for preparation of water based pH dependent black coloured hair with said application of tannin source followed by ferrous ammonium sulphate with altered pH of 9 from 6.
According to another aspect of the present invention there is provided a method of colouring the hair comprising sequentially applying the pH dependent hair colour ingredients on hair selected from
a. tannin in the levels of 5-25% wt./v as a water based hair colour active combination;
b. ferrous ammonium sulphate in the levels of 5-25% wt./v as a water based hair colour active combination;
c. potassium carbonate as pH modifier to favour generating the pH range of said formulation of 7-9 for ionization of tannin and/ or altering the degree of dissociation of ferrous ammonium sulphate to favour intense colour shades of brown to black with low RGB values of 30 to 40;
maintaining tannin : ferrous ammonium sulphate as hair colouring actives in the range of 1 to 5 : 5 to 1 preferably 1 : 1.
According to another preferred aspect of the said invention there is provided said method wherein said sequential applications of the pH dependent hair colour ingredients on hair involve water based colouring of hair following the sequence of:
a. providing tannin source solution on hair by changing the pH from 3 to 7-9 by potassium carbonate;
b. providing solution of ferrous ammonium sulphate thereafter involving total application time of 1 to 60 mins at room temperature to obtain brown coloured hair therefrom which is free of any required intermediate washing between said application in step a) and step b).
Preferably in said method said sequential application of the pH dependent hair colour ingredients on hair involves a water base colouring of hair following the sequence of:
a. providing tannin solution on hair;
b. providing solution of ferrous ammonium sulphate by changing the pH from 6 to 8 by potassium carbonate thereafter involving total application time of 1 to 60 mins at room temperature to obtain black coloured hair therefrom which is free of any required intermediate washing between said application in step a) and step b).
Advantageously said method optionally involves the steps of
i. carrying out said colouring of the hair in the range of 40-75 °C for 1 to 15 mins to favour hair colouring in desired intense colour shades with very low RGB values of 30 to 40 under reduced concentration of the ingredients in the range of 5-10% w/v; with or without further step of
ii. applying sonication treatment to the hair for 1 to 15 mins to favour colouring of the hair in desired colour shades under reduced concentration of the ingredients in the range of 0.1-5 % w/v.
More advantageously, said method of colouring the hair involves tannin-iron complex imparting stable wash proof colour on the hair free of any p-PDA based ingredients and any other toxic ingredients.

DETAILED DESCRIPTION OF THE INVENTION
As discussed hereinbefore the present invention provides for a hair colouring formulation/kit for generating tannin-iron complex based stable wash proof hair colour that is pH dependent and a method of colouring the hair comprising sequentially applying the pH dependent hair colouring ingredients selected from tannin source, ferrous ammonium sulphate and potassium carbonate as pH modifier, affecting the degree of dissociation of salts and ionization of tannin also influencing its activity, all in selective amounts and in simple water base to provide for darker colour on the hair free of any additional ingredients and any additional intermediate washing of hair while application of the selective ingredients.
It was thus surprisingly found by way of the present invention that upon selective control of the ingredients its concentration, ratio, pH of hair colouring formulation/ kit and by following the process parameters of method/ sequence of adding reactants and washing, a darker hair colour could be achieved by a simple hair colouration formulation/ kit comprising selectively tannic acid, potassium carbonate and ferrous ammonium sulphate in water base free of typical dye reagents of ammonia, hydrogen peroxide, and sodium sulphide and other hair damaging ingredients.
It was thus a selectively found by way of the present invention that treating hair with tannic acid followed by ferrous ammonium sulphate resulted in darker colour than simultaneous addition and/or treatment with ferrous ammonium sulphate followed by tannic acid.
Further altering tannic acid pH from 3 to 7-9 resulted darker colour. Further, the change in the pH of ferrous ammonium sulphate from 6 to 9 resulted in the change of colour from brown to black.
It was also found that sequential dipping of the hair sample in the first ingredient followed by the second ingredient without any cleaning or drying step in between as per the literature gray hair samples acquired intense black colour.
Effect of temperature on the colour formation involving the hair colour formulation/ composition as above revealed that the time required for colouring can be reduced considerably at little high temperature. The reaction temperature of 40-75 °C was found to be feasible temperature for colouring hair. The time taken for colouring hair reduced form 60 minutes to 15 minutes for each treatment. Similar to time reduction, when the hair colouration formulation was applied at a temperature range of 40-75 oC the concentration of the precursor could also be reduced from 25 % to 5-10 % to provide for the same intensity of colour shade.
Further sonication during treatment was effective to reduce the concentration of the precursor material in the hair colour formulation/ composition required from 25% w/v to 5 % w/v and also advantageously reduced the colouring time from 60 min to 15 min.
The reaction involved in the process is given below in Scheme 1

Scheme 1

The present invention is targeted to improve the process and significantly enhance the performance of the hair colour prepared by Fe-salt and tannin with the following advantageous features:

a. The process of the present invention is completely free of any reducing agents such as sodium sulphide and other chemicals as penetration enhancer employed on hair and is thus devoid of any adverse effect, like breaking of the di-sulfide bond of hair to render the hair mechanically weak. Selective pH control of the ingredients enabled hair colouration in intense shades by simply employing the ingredients of tannin, potassium carbonate, and iron salt in water base;

b. The sequence of dipping the hair in two different precursors had high impact on the outcome of the process. Dipping in tannin followed by dipping in Fe-salt is a preferable sequence of application rather than the reverse sequence;

c. Two popular colour shades could be developed by way of the present invention employing the same method and precursors by only following a selective sequence of addition. In this two steps dying process, the hair swatches were not washed when switching between the steps. It was found by way of the present invention that when K2CO3 was added in tannin in the presence of Fe-salt it produced dark brown colour and when K2CO3 was added to Fe-salt the colour changed to dark black. The exclusion of washing sequence further led to the improvement in the colour intensity of the dyed hair as well as reduced the hassle in colouring process;

d. Other additional reagents did not prove effective in the process of the present invention rather weakened the colour intensity;

e. Ultra-sonication reduces the time and %wt/v of the ingredients required during the dyeing process;

f. Increase in the temperature reduces the time and concentration of precursors required to achieve similar colour at room temperature. Therefore, the process of the present invention is cost effective as well as user friendly in requiring less application time.

It is thus possible by way of the present advancement to provide for a hair colour formulation/ kit and method of colouring the hair involving the same comprising tannin source, ferrous ammonium sulphate and potassium carbonate all in water base to favour hair colouration in intense shades of brown to black with very low RGB values. The sequence of addition of ingredients, together the temperature and sonication effects were found to be prominently effective in advantageously reducing the application time and % wt/v of the ingredients. More advantageously, said hair colouring formulation/ kit in the absence of any penetration enhancers, p-PDA based colouring components, and other hairs damaging actives is both cost effective and safe for application involving reduced application time in simple water base.