NO134184B - - Google Patents

Description

The invention relates to a treatment of hair to give the hair

desired physical form.

Methods for modifying keratin-containing materials, such as e.g. those used for the treatment of human hair to permanently curl or condition etc. these, and the treatment of keratin-containing fiber materials to change one or more of the properties of such a material in accordance with predetermined requirements, are well known in the art and are extensively described both in the patent literature and other published literature. For permanent curling of human hair, usual processes always include an initial impregnation treatment of the hair with a suitable reducing agent, after which the hair is modified chemically and/or physically using a suitable oxidizing agent. The various materials and processing solutions necessary to make such methods possible are well known in the art and are commercially available in a variety of forms. Although widely used commercially, hair conditioning methods of the above type have nevertheless been found in practice to have unacceptable deficiencies for one or more important purposes. The main objection is perhaps that with such a treatment it is not possible to obtain a finished hair with the necessary shape stability and other desirable properties, such as a suitable hygroscopicity, so that the hair's flexibility can be preserved while avoiding excessive brittleness or hardness etc. Moreover A number of the previously proposed hair treatment processes have always produced a hair product which has had insufficient fullness, thickness or shine etc. The preparations which have been prescribed for use in such treatments also in a number of cases give film deposits with a poor adhesion and which have a highly undesirable tendency to flake off, dry to a hard deposit and/or discolour the hair, thereby ruling out any possibility of achieving the desired glossy appearance.

Other disadvantages that the currently commercially available hair conditioning preparations suffer from are their tendency to

hot to break up or otherwise adversely affect the structural integrity of the hair fiber itself, e.g. elastic properties and tensile strength properties etc. This is of course of the greatest importance as damage of this kind, whether it can be repaired or not, always manifests itself in the form of dull, lifeless hair that is very difficult to care for. In other cases, it has been established that the colourability, i.e. the receptivity or affinity of the hair fibers to dyes, is adversely affected by a given hair conditioning treatment.

For permanent curling of hair or the opposite, i.e. straightening of hair, when using the currently available preparations and techniques, it is necessary that the hair is treated while it has the desired physical form. Use of e.g. papillotes during the chemical treatment steps for the hair are thus necessary because the chemical treatment fixes the physical form. As soon as the hair's shape has been fixed, it is relatively shape-stable, and any desired change in the physical shape requires a completely new chemical treatment, i.e. complete permanent curling.

It is therefore clear that the special requirements of a given hair conditioning treatment can vary considerably, i.e. from treatments that are primarily intended to produce curls or waves etc. in the hair, to treatments that are only intended to change one or more of these properties such as tensile strength, elasticity, dye receptivity and thickness.

Because of this, considerable industrial activity has been concentrated around research and development of methods and preparations for use in these and which are particularly and advantageously suitable for use in connection with the intended modification of hair fibres.

In accordance with the recognition that is the basis of the present invention, it has been established that one or more of the properties of hair can be modified in accordance with pre-set requirements by using a method that includes a special treatment sequence with special preparations.

The invention thus relates to a method for treating hair to give it a desired physical shape, and the method is characterized by the fact that the hair is treated with a reducing agent to convert at least part of the disulfide bonds in the hair into mercaptan bonds, the remaining reducing agent is removed from the hair by rinsing, the hair is treated with an oxidizing solution comprising a peroxide catalyst material and an olefinically unsaturated monomer compound containing at least one group of the formula

or an olefinically unsaturated compound of the formula

wherein each of the R groups is independently hydrogen, halogen, alkyl, alkoxy, aryl, a"cyl, carboxy, carbaloxy or carboxamide, and which can be polymerized in the presence of the peroxide initiator, whereby the monomer is graft polymerized onto the hair which is then rinsed to remove unreacted monomer and initiator, given the desired physical form in the wet state and dried with the desired physical form, after which the hair is re-moistened with complete loss of shape retention, re-laid in any desired form and dried, one or more times.

Experimental results have indicated that a polymerization reaction occurs due to the mutual and intimate contact between peroxide, initiator, monomer and reduced keratin in the hair, which thereby acquires a large number of "active" centers in the form of reduced disulfide, i.e. sulfhydryl groups or mercaptan bonds.

It will be understood that the disulphide bonds present in the hair comprise reducible groups which can be converted to sulphydryl in the presence of relatively strong reducing agents, such as thioglycolic acid. The sulfhydryl groups formed due to the reduction treatment are strongly inclined to react with peroxy initiator compounds with a simultaneous formation in situ of free radicals which are effective agents for initiating the polymerization of vinyl-type monomers. The main part of the initiation of the monomer polymerization and the propagation thereof is thus limited to the reaction polymer which binds to the hair fiber as an integral part thereof, both chemically and physically.

It is of course recognized that it has previously been proposed to treat keratin-containing substrates, such as wool, with a monomer solution in the presence of a redox catalyst system which is capable of liberating free radicals under the treatment conditions, as such treatment is done so that the substrate will have one or more desirable characteristics. The present method is, however, in a number of respects strongly different from the known methods.

It was thus absolutely necessary for an effective utilization in practice of the above methods that the reduction treatment was sufficient to achieve a significant reduction of the keratin substance, i.e. that the conversion of disulfide bonds to sulfhydryl groups was so strong that the desired change of the keratin substance by a subsequent treatment with an oxidizing solution could be achieved. This method differs from the treatments common in the field of technology, which provide a simple impregnation of the hair fiber with the reducing agent. With the latter methods, no chemical reduction of the keratin substance is achieved, as the treatment is only intended to deposit a sufficient amount of the reducing agent on the hair for reaction with a subsequently applied oxidizing solution. The keratin substance is therefore essentially not affected, at least chemically, by the reducing solution, but mainly serves as a carrier material. By therefore using such methods, the catalyst-containing monomer solution used in a later step during the treatment reacts with the reducing agent itself and not with the keratin substance, whereby the oxidation-reduction reaction is limited to the parts of the hair that contain the previously deposited reducing solution. In contrast, the original reduction treatment in the present method leads to a chemical change of the keratin-containing substance, i.e. reduction of the disulphide to mercaptan. The hair itself therefore acts as the reducing agent component in the redox catalyst system for the release of free radicals, and the catalyst system is activated by the subsequent addition of an oxidizing solution. In order to ensure such a condition, it is of the utmost importance when applying the method described above that a rinsing step is introduced between the reduction step and the oxidation step, thereby making any possibility of the reducing agent as such remaining in the treated hair as small as possible. possible. The importance of rinsing as a critical step in the treatment sequence used in the present method will be clear from what follows. It will be understood that when the reducing agents are applied, they will tend to penetrate the overall volume of the hair. - the solution will thus, in connection with hair, be deposited to a large extent in the free space or the spaces between the separate hair fibers present in the hair, and more particularly at or near the surface of the fiber. The extent of the accumulation of the reducing agent

in such areas will of course depend on a number of factors, including the amount of reducing solution used, the treatment conditions, e.g. time and temperature etc., and the condition of the hair, i.e. the degree of porosity etc. It will be easily understood that when the solution

of initiator and monomer comes into contact with the hair under conditions that promote the polymerization of vinyl monomers, the polymer-forming reaction will not be limited in any way to the immediate surroundings of the hair fibers, but will of course take place unimpeded in the above-mentioned areas of free space due to the fact that where large amounts of reducing agent are present. This leads to the highly undesirable condition "solution polymerization" which causes the hair fibers to bind together. In connection with hair, solution polymerisation can thus cause an uncontrollable intertwining of the hair fibers which leads to the formation of knots, tangles and other irregularities which make quick and easy styling of the hair extremely difficult. The last mentioned disadvantages are of course completely eliminated by using the special order of. treatments according to the present method. The necessary use of an intermediate rinsing step to completely remove the reducing agent from the hair thus ensures that a solution polymerization will not occur to any significant extent, the polymerization being limited therein. essential only to the hair fibres. This result must necessarily be obtained because each individual reduced hair fiber forms an area for the formation of polymerization-initiating free radicals, and the polymerization proceeds "inside" as opposed to "outside" the hair fiber.

Although any of the reducing agent compounds commonly used in the art of treating keratin-containing hair can be advantageously used in the present method, it has been shown that particularly advantageous results are obtained with reducing agents of the more active type. Strong reducing agents are preferred because they lead to an economically more acceptable practice and a better quality control. By using stronger reducing agents, any necessity for longer treatment times with reducing agents is thus avoided while at the same time a significant reduction of the hair is achieved.

Besides eliminating any possibility of any substantial solution polymerization, the above-described method also makes it possible to achieve an increased uptake of polymer compared to known methods. By using the present method, a several-fold increase in the amount of polymer that can be grafted onto the hair in a short time can thus easily be achieved. The present method for graft polymerization is more particularly without further ability to provide an at least 10-fold increase in the amount of grafted polymer compared to known methods which are carried out under similar conditions. A feature of the greatest importance, and perhaps the most important characteristic of the present method, is that the hair treatment can be carried out under reduced temperature conditions, i.e. at a temperature of only 18-24°C.

In comparison, it is always necessary to use high temperatures, i.e. a temperature of at least 60°C, for effective utilization in practice of the methods described in the art. The high temperature that must be used apparently constitutes a limitation for the applicability of such methods as attempts to

lead to these, but at temperatures significantly lower than 60°C, it is prevented because the polymer-forming reaction does not take place to a practically acceptable degree.

It will be understood that the sequence of treatments used in the present method necessarily includes a reduction as the first step. This particular sequence is necessary because the keratin-containing substance must act as a reducing agent during the oxidation or polymerization phase. In contrast to this, with the known methods, it has been possible to use a considerable variation in the order of treatment to such an extent that the oxidation step can be carried out before the reduction without in any way excluding or otherwise hindering the achievement of the purpose of the treatment. In some cases, a prior oxidation actually constitutes a preferred embodiment. This ratio serves to emphasize the relatively low importance of the function of the keratin-containing substrate in such known methods. It will be easily understood that the keratin-containing substrate is inert and only serves as a carrier material for the reducing solution or the oxidizing solution and does not in any way take an active part in the redox reaction that leads to the formation of free radicals. The substrate is simply the material to be affected by the redox treatment. In contrast to this, in the present method the keratin-containing substrate in the form of hair has a dual function, i.e. (1) as a reducing agent and (2) as the material to be changed.

As stated above, the present method essentially consists of three basic steps which are carried out in order and . which can be termed (1) reduction, (2) flushing and (3) oxidation. In order to facilitate an understanding of these important aspects of such a procedure, each of these steps will be dealt with in more detail.

1. Reduction

The reduction of the keratin-containing hair can be carried out using any of the reducing agents recognized in the art as common for such purposes. Such materials are of course well known and a highly specified list of suitable examples of such should not therefore be necessary. It should be sufficient to emphasize that the reducing agent specially chosen for use must be used under such conditions that a significant reduction of the keratin-containing substance in the hair is ensured. Suitable materials thus include water-soluble salts, e.g.

alkali metal salts and ammonium salts of thioglycolic acid, e.g. sodium thioglycollate and ammonium thioglycollate etc., and potassium bisulphite etc., water-soluble salts of thioglycerol and trihydroxy-methylphosphine which can also be formed in situ from tetra-kis-hydroxy-methylphosphonium chloride etc. As indicated above, strong reducing agents are preferred. That these are preferred is, however, mainly due to practical considerations, e.g. reduced processing time. Weaker reducing agents can thus be used, but the use of such materials entails correspondingly longer treatment times to achieve the desired degree of reduction of the keratin-containing substance. The reducing agent can be used in the form of a simple aqueous solution or in a mixed solvent system of water-miscible organic solvents, such as monohydric and polyhydric alcohols, e.g. methanol, ethanol, propanol, isopropanol, n-butanol, ethylene glycol and 1,2-propylene glycol etc. and other glycols, e.g. ethylene glycol monomethylether etc. The choice of a particular solvent system will to some extent depend on the type

of the reducing agent used.

Thus, in connection with the above-mentioned reducing agents, it has generally proved advantageous to use mixed solvent systems for e.g. bisulphite compounds, but simple aqueous solutions are sufficient for the thioglycolate derivatives. The relative amounts of water-miscible organic solvent used are not particularly critical, apart from the requirement that such a material must be used in a sufficient amount to promote the solubility of monomer and/or catalyst in the reactant. An excess of organic solvent should, however, be avoided in connection with water-insoluble, organic solvent-soluble monomers in order to thereby make the problems associated with a contact between monomer, keratin and initiator as small as possible. Although higher concentrations may well be used for carrying out the present method, the used concentrations of such materials should be kept below approx. 7 5% for achieving optimal results, but not because of the feasibility of the present method. Increasing amounts of organic solvent usually lead to reduced rates of absorption of polymer by the hair when treated with the oxidizing, monomer-containing solution. This may be due to one or a number of factors. It will be understood that a portion of the amount of solvent used for the reduction treatment is retained in the hair despite the use of an intermediate rinsing step. An application of "reduction" solvent systems in which the later introduced monomer component has an essentially unlimited solubility can thus act to effectively reduce the rate of uptake of polymer by the hair as the monomer's affinity towards the solvent is greater than its affinity: towards the hair. It has been shown in connection with the above-mentioned solvents that the lower alkanols, such as e.g. ethyl alcohol, are particularly advantageous to use in the present method. An optimal realization of the advantages that have been made possible to achieve by the present method can in all cases be achieved by using the water-miscible organic solvent in a concentration of up to approx. 50% by weight of the solution, i.e. 0-50% by weight, preferably 20- approx. 45% by weight, the rest being water. It is also recommended that the reducing solution used is essentially saturated with reducing agent, as experiments have shown that higher rates of polymer absorption can be achieved with increasing concentrations of reducing agent, as optimal results are obtained by using saturated solutions. The required amount of reducing agent to give a saturated solution will of course mainly depend on its solubility in the solvent system used. Such limiting data for the solubility can easily be derived for a given case by routine examination in the laboratory.

The concentration of the reducing agent used can vary within relatively wide limits depending on, among other things, that such a material's reducing power. Water-soluble salts of thioglycolic acid, e.g. ammonium thiglycollate, can e.g. used with good effect in a concentration of approx. 6% by weight of the solution, whereby a pH of approx. 9. Solutions of the thioglycollate derivative can be easily and simply prepared by diluting e.g. 98% thioglycolic acid with water and then increase the pH by adding concentrated ammonium hydroxide. Sodium bisulphate is a somewhat weaker reducing agent and can thus be used with good effect in somewhat higher concentrations. In all cases, it has been shown that good results can be achieved

by using reducing agent within a concentration of 1-20% by weight, preferably 3-20% by weight, of the solution. When using bisulphite, it is generally preferred to maintain a slightly acidic pH

in the solution, i.e. that too strong acidity should be avoided.

As indicated above, the duration of the reduction treatment will vary depending on a number of factors, including the concentration of the reduction solution and the type and extent of the hair being treated, etc. It has been shown in all cases that reduction times of approx. 30 minutes duration are very well suited for achieving the purposes described herein. It is then of course required that the reduction treatment must be sufficient to achieve the desired degree of disulphide reduction in the hair.

The reducing solution may also contain varying amounts of one or more added ingredients of an optional nature to increase or otherwise promote the overall effectiveness of the reducing solution. Moisturizers can thus e.g. is used to reduce the surface tension at the interface between the hair and the reducing solution to thereby promote penetration of the reducing solution into the hair fibres. Preferred surface-active agents for this purpose include non-ionic surfactants, i.e.

of the polyoxyalkylated type, although it has been shown that certain anionic materials, e.g. sulphonates, can also be used with advantage.

The total volume of the reducing solution used for the treatment will also vary again depending on such factors as the concentration and activity of the solution and the type of hair etc. Optimal amounts of the reducing solution can always be easily determined by routine examination for a given case.

2. Rinsing.

When the reduction treatment described above is over, the treated hair is rinsed well to ensure that remaining, unreacted reducing agent is substantially completely removed. This can be effectively achieved by a simple washing with water. No particular difficulties arise in connection with carrying out this step as the reducing agents which are water-soluble can be easily removed by rinsing with water. However, it should be emphasized again that even if the rinsing is easy to carry out, it nevertheless constitutes a very decisive and important phase of the present method as a beneficial effect of the entire treatment is completely dependent on it. As indicated above, the main purpose of the rinsing is to remove or to reduce to a minimum any possibility of polymerization taking place to any significant extent within the interstices or voids in the hair. In this way, the difficulties associated with unwanted interlinking, tangling and knot formation etc. in the hair are avoided.

3. Oxidation

The third step in this sequence, which is used in an embodiment of the present method, comprises oxidation.

The essential components of the oxidizing solution used in the treatment of the hair include monomer and peroxide initiator for the release of free radicals. The monomer material used can be chosen from a relatively large number of monomers which can be polymerized in the presence of the catalyst for the release of free radicals. The monomer must contain at least one group with the formula:

The aim is therefore to use both mono- and polyethylenically unsaturated compounds. Such monomer materials can also, for simplicity, be represented by the following structural formula:

where R is hydrogen, lower alkyl with 1-4 carbon atoms, e.g. methyl, ethyl, propyl, butyl and isobutyl, and R 1 is (a) carbyloxy, i.e. -COOR 2 /wherein R 2 is hydrogen, alkyl containing 1-20 carbon atoms, e.g. methyl, ethyl, n-pentyl, octyl, lauryl or stearyl, alkenyl containing 3-10 carbon atoms, e.g. allyl, . 3,4-butenyl, 2,3-butenyl,5,6-hexenyl or 2,3-hexenyl, hydroxyalkyl containing 2-10 carbon atoms, e.g. 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxybutyl, 2,3-dihydroxypropyl, 2,4-dihydroxybutyl or 4,6-dihydroxyhexyl, alkyl and dialkylaminoalkyl, each alkyl group preferably containing 1-4 carbon atoms. e.g. 2-N-methylamino-ethyl, 2-N,N-dimethylaminoethyl, tert.butylaminoethyl, 2-N,N-di-methylaminoethyl or 3-N,N-diisobutyl-aminopropyl, halo-alkyl containing 1-10 carbon atoms, f .ex. hexafluoroisopropyl, per-fluoroethyl, perfluoropropyl, 2-difluoro, 3-trifluoropropyl, 2-chloro-ethyl, 2-chloropropyl or 1,1,9-trihydroperfluorononyl methacrylate, juxtaposed epoxy-alkyl containing 3-6 carbon atoms, e.g. glycidyl, 3,4-epoxybutyl, 4,5-epoxypentyl or 2,3-epoxybutyl, (b) amide groups comprising both substituted and unsubstituted forms and with the following structural formula:

where R 1 and R 4 are hydrogen, alkyl, preferably lower alkyl, or may represent the atoms necessary for the completion of a polyunsaturated molecule, which

where R,, is an alkylene bridge containing preferably 1-4 carbon atoms, such as methylene, ethylene, propylene or butylene, (c) halogen, such as chlorine or bromine, (d) alkoxy, e.g. methoxy, ethoxy or cyclo-hexoxy, (e) a cyano group, i.e. -C=N, (f) alkenylaryl where the alkenyl group contains 1-4 carbon atoms, i.e. lower alkenyl, e.g. o-, m- and p-

The above-mentioned monomer materials can also be used in the form of their salt derivatives. e.g. salts with cations that dissolve in water. In connection with acrylic acid and methacrylic acid, the monomer material can thus be converted into a suitable salt form, such as e.g. calcium acrylate, i.e. (GH2=CH-COO )2Ca++' sodium acrylate, potassium acrylate or calcium methacrylate.

In addition to the above-mentioned monomer compounds he. r it has also been shown that other olefinically unsaturated compounds lead to essentially similar properties in the keratin-containing substrate, although the mechanism need not be a polymerization or graft-copolymerization, but perhaps rather a modification of the keratin (i.e. polyamide) chain comprising an, optionally arbitrary, binding of units of the olefinic compound to the keratin chain. Such compounds are.examples of compounds of. the more general formula:

where each of the R groups is, independently of each other, hydrogen, halogen, alkyl, alkoxy, aryl, acyl, carboxy, carbaloxy, or carbox-amido etc. The preferred monomers are the α,, ^'-unsaturated dicarboxylic acids and - anhydrides, such as maleic acid, itaconic acid and citraconic acid.

As examples of materials covered by the above definition and description, mention can be made in particular of methyl ethyl ethacrylate, ethyl acrylate, butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, isooctyl methacrylate, tert-octyl methacrylate, allyl methacrylate, glycidyl methacrylate crylate, 3,4-epoxybutyl acrylate, 2,3-epoxybutyl methacrylate, 4,5-.epoxypentyl methacrylate, methyl acrylate, butyl acrylate, allyl acrylate, 3 , 4^butenyl acrylate, 4 , 5-pentenyl methacrylate, 4 , 6-hexeryyl acrylate, lauryl methacrylate, tridecyl methacrylate, tetradecyl methacrylate , cetyl methacrylate, octadecyl methacrylate, eicosyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydr<p>xypropyl acrylate, 2,4-dihydroxy-butyl methacrylate, 2-tert. butylaminoethyl acrylate, 2-tert. butyl aminoethyl methacrylate, 2-N,N-dimethylaminoethyl methacrylate, 2-N,N- / v dimethylaminoethyl acrylate, ethylene glycol moiromethacrylate, hexa- , fluoroisopropyl acrylate, hexafluoroisopropyl methacrylate, perfluoroethyl acrylate, 2,2-difluoropropyl methacrylate, perfluoroisobutyl acrylate, 2-fluoroethyl methacrylate, methacrylic acid , acrylic acid, 2-dimethylaminoethyl methacrylate, 2-(2-diethylamino)-ethyl methacrylate, methacrylamide, acrylamide, 1,2-propylene chloride, vinyl chloride, vinyl bromide, vinyl fluoride, N-tert.butyl methacrylamide, N,N-dipropy1-acrylamide, N ,N"*"-methylene-bis-acrylamide, N^N^-ethylene-bis-(N,N^-diethyl)-acrylamide, N,N"''-propylene-bis-(N ^N—di- isopropyl) ^methacrylamide, acrylonitrile, methyl vinyl ether, propyl vinyl ether, iso-butyl vinyl ether, methyl isopropenyl ether, divinylbenzene, malein-

acid or anhydride, itaconic acid or anhydride and citraconic acid or anhydride.

In connection with the multifunctional monomer materials, e.g., allyl methacrylate and divinylbenzene, it will be understood that considerable crosslinking can occur in addition to the dominant graft copolymerization during the oxidizing treatment of the hair. This result is obtained because the monomer material of this type has more than one group that can be polymerized under the reaction conditions used. It will also be understood that the monomer materials which are calculated

for use in the present method, can be used individually or in a mixture of two or more. The choice of the particular monomer systems will mainly depend on the demands made by the user depending on the type of hair being treated, the desired properties of the end product or the reactivity of the monomer etc.

As stated above, it also contains oxidizing solution

a peroxide initiator material capable of releasing free radicals and initiating the polymerization of the vinyl monomer in the presence of the reducing agent, i.e., mercaptan. Initiator materials which are suitable for these purposes are well known in the art and are extensively described in the published literature and include both the organic and inorganic peroxides, hydroperoxides and peracids etc.

Particular examples of suitable initiators include cumene hydroperoxide, hydrogen peroxide, barium peroxide, benzoyl peroxide, acetyl peroxide, tert.butyl hydroperoxide, alkali metal salts of organic hydroperoxides, alkali metal salts of peracids, such as peracetic acid, perbenzoic acid and persulfuric acid. It has generally been shown that particularly good results for the rate of uptake of monomer can be achieved by using initiator compounds soluble in organic solvents, such as e.g. cumenhydoperoxide which is of course insoluble in water. Although somewhat poorer results are typical for methods where water-soluble peroxygen compounds are used compared to materials which are soluble in organic solvents, such methods have nevertheless proven to be very satisfactory.

The initiator and monomer materials can be formed by using simple aqueous solutions or systems of mixed solvents, the type and relative amount of the solvent materials used being dependent on the typical solubility properties of the monomer and catalyst components. The solvent used should as a rule comprise 10-90% by weight of water and the remainder a water-miscible organic solvent, such as a lower alkanol, e.g. ethanol, n-propanol, isopropanol or n-butanol, and acetone. Within the range indicated above, the selection of the particular amounts of organic solvent will depend on, among other things, how hydrophobic the monomer component is. A use of strongly hydrophobic monomer materials, either alone or in a mixture, can thus make it necessary to use increased amounts of organic solvent to facilitate the achievement of a uniform and homogeneous dispersion of the relevant monomer and catalyst components. The use of a hydrophilic monomer component can, in turn, make it necessary to use a correspondingly increased amount of water.

Regardless of the type of monomer material used, a further and important consideration must be made when preparing the oxidizing monomer solution. It will be understood that the effectiveness of the overall method is entirely dependent on effective contact being achieved between the constituents present in the oxidizing solution and the mass comprising the reduced hair. Conditions should therefore be ensured that the promoter makes such contact during the treatment in order to thereby ensure the achievement of optimal results.

The relative amounts of solvent used in the preparation of the oxidizing solution should therefore be chosen so that a medium is obtained in which the monomer material can easily react with the hair under the conditions used for the treatment. It is therefore generally recommended in practice as organic solvents to use one or more of the lower alkanols of the above type as these have been shown to ensure the achievement of optimal results. In contrast, solvents of the ether type, and especially the ether glycol type, e.g. ethylene glycol monomethyl ether, somewhat worse and leads to reduced rates for the uptake of monomer. However, this should not be interpreted as meaning that the latter solvent materials must necessarily be used in the present process, as special conditions may indicate that it is better to use somewhat lower grafting rates. These things are again mainly left to the user to decide.

The oxidizing solution can likewise be used in the form of a suitable dispersion, suspension or emulsion etc. depending on the solubility properties of the monomer used. This can easily be achieved by using suitable suspending agents or emulsifying agents, etc., and the special additives that can be used for such purposes are well known in the art. The form in which the monomer is used, i.e. as an emulsion or solution, etc., is in fact of secondary importance, as the main requirement is that such a material must be available for use with the reduced hair. For this purpose, the monomer can be used in a number of forms, with the condition that there is effective contact between monomer and hair.

The relative amounts of the monomer and catalyst used for the preparation of the oxidizing solution are not of decisive importance for carrying out the present method. It is thus only necessary that the monomer material is used in a sufficient amount so that the desired degree of turnover with the hair can be achieved, and the concentration of the catalyser material is similarly required. only be sufficient to give the desired reaction rate. The monomer concentration will therefore be increased in cases where a significant degree of reduction is desired, and conversely the monomer concentration can be reduced if

a smaller degree of reduction is desirable. It will be understood that in those cases where the monomer material is used in liquid form,

e.g. methyl methacrylate, the oxidizing solution may simply comprise the monomer and the catalyst. The monomer material can thus be used in a concentration of 1 - approx. 99% by weight, preferably 5-30% by weight, of the total oxidizing solution. The quantity of the catalyst material can likewise be varied within wide limits

at a molar ratio between catalyst and monomer of 0.001:1-5:1, preferably 1:8-1:2. Within the range indicated above, the specifically chosen quantity will depend on a number of factors including, e.g. the reactivity of the monomer material,: its concentration and

the desired degree of thiol formation. The optimal parameters in this connection can always be easily determined for a particular case by routine examinations.

The duration of the treatment with the oxidizing solution is usually 30 minutes - 2 hours to achieve one significant modification of the hair. In most cases, it has been shown that oxidation times of the order of 30 minutes are sufficient to achieve the desired reaction. The optimal reaction time will again for a given case depend on the reactivity of the monomer component or the desired degree of modification of the hair etc; However, one of the important features of the above-described method consists in the fact that advantageous results can be obtained by carrying out oxidation treatment. the action at room temperature. In contrast, the previously proposed methods for treating keratin-containing substrates have always required the use of relatively high temperatures, i.e. of the order of at least 60°C, in order to achieve the desired degree of modification of the substrate within treatment times that are commercially acceptable in practice. One of the truly surprising aspects of the present method is thus connected with the discovery that an effective modification of the hair can be achieved despite the use of very mild temperature conditions, i.e. room temperature, and treatment times of the order of only 30 minutes. The importance of this particular aspect of the present method becomes clear if it is taken into account that the possibility of damaging the hair increases considerably as the treatment conditions become more intense, and especially with increasing temperature. The relatively low temperatures that are characteristic of the present method involve little or no risk of damage to the hair.

V The method described above is required in the applicants' published patent application no. 20.39/70.' It has also been shown that for the process described above it can be advantageous to use a water-soluble halide salt in the monomer solution. The type of cation which promotes solubility in water is not particularly important, as the main requirement is that such a cation must not have any tendency to adversely affect the hair or its immediate surroundings. As particular examples of water-soluble halides which have proven to be particularly suitable for use in the present method, mention can be made, for example lithium bromide, lithium chloride, sodium bromide, sodium chloride, potassium bromide, potassium chloride, ammonium bromide and ammonium chloride. The above-mentioned bromides and chlorides are distinctive in that they have a very strong ability to considerably increase the achievable speed of the graft copolymerization. Even a use of the halide salt in relatively small amounts therefore makes it possible to achieve a several-fold increase in the speed of the polymerization reaction, whereby increased amounts of polymer can be grafted within a given time. processing time. The halogenide concentration used can likewise vary within relatively wide limits. As a rule, it will turn out that beyond certain concentrations, a portion-wise increase in the amount of halide used will not lead to any corresponding increase in the rate of podnihgs polymerization, ie the gradual increase in the action of the halide compound tends to decrease at higher concentrations. In any case, a considerable improvement in the speed of the polymer podnirig can always be achieved by using the halide salt in a concentration of 0.025- approx. 40 mol/mol monomer, with a range of 4-

10 mol/mol monomer has been found to be particularly advantageous. The halo gen ion apparently contributes in an effective way to the reaction mechanism that leads to the formation and release of free radicals. The halide salt, e.g. lithium bromide, thus occurs to react with the peroxide catalyst materials, e.g. potassium persulfate, with the release of the free radicals in accordance with the following reaction sequence:

In the presence of reduced hair fibers, a chain transfer can take place, and the reaction in question can be represented as follows:

Experimental results have likewise suggested that the very large improvement in the rate of the graft copolymerization cannot simply be explained by reference to the above. The halide compounds present apparently promote a swelling of the keratin mass in the hair fibers, while the absorption of peroxide catalyst and monomer is favored in accordance with concentration effects.

The hair treated and modified by the present method is then well moistened with water and "fixed" in any desired shape while damp. It is then allowed to dry in the "fixed" form. The result is a very unique and unexpected degree of shape stability itself. under conditions of relatively high humidity, e.g. 85% r.f. Another notable feature of the modified hair is that it can be repeatedly given any physical form if it is first wetted and then dried with the chosen physical form.

In the following examples, all parts and percentages are based on volume if nothing else is stated.

Example 1-16

As stated above, there are a number of factors that have a considerable impact on the effectiveness of the treatment with the redux ion solution, i.e. expressed by the ability of the thus treated hair to take up monomer during the oxidation step. This is shown in these examples where human hair was treated. In each case, the reduction treatment was carried out at room temperature for up to 30 minutes using approx. 20 ml reduction solution per grams of hair. After the reduction treatment was over, the hair sample was thoroughly rinsed to completely remove the remaining reduction solution. The oxidation treatment was then carried out using one solution consisting of 12% methyl methacrylate monomer, 5% cumene hydroperoxide catalyst and 41% ethyl alcohol with the balance being water. The hair sample chosen for the treatment was in each case weighed both before and after the treatment, and the weight increase, i.e. the degree of grafting of polymer, was calculated by subtracting these weights from each other.

An increase in the time for the treatment with the oxidizing solution generally results in a corresponding stepwise increase in the amount of grafted polymer. This is shown in the following examples which indicate the results obtained in connection with a treatment with methyl methacrylate.

In each of the examples, the reduction treatment was carried out using a 6% solution of ammonium thioglycollate with a pH of 9 and at a treatment time of 10 minutes. Human hair samples were processed. Moreover, in each case the reduction solution was used in a volume of approx. 20 ml per gram hair sample that was treated. After the reduction treatment was over, the hair sample was thoroughly rinsed to completely remove the remaining reduction solution. For each of the experiments, the treatment with the oxidizing solution was carried out for 30 minutes at room temperature using 20 ml of oxidizing solution per; gram hair sample. The results obtained are reproduced in table 2.

It is clear that considerable amounts of polymer were effectively grafted onto the hair sample that was treated, despite the fact that moderate room temperature conditions were used. It will also be understood that the grafted polymer quantity will also be strongly influenced by the number of available reduction sites on the hair being treated, depending on the time, and if the number of available reduction sites decreases considerably, the rate of grafting of the polymer will correspondingly decrease. This is also evident from the results indicated in connection with the treatment with the oxidizing solution for 5-20 minutes. Thus, with an initial gradual increase from 5 to 10 minutes, an approx. 3-fold increase in the percentage grafting. In contrast, increasing the time of treatment with the oxidizing solution from 10 to 15 minutes gave an approx. 2 times increase in the percentage grafting. It is clear from these data that the relative increase in the percentage grafting tends to decrease relatively strongly if the treatment time is increased beyond this.

Cumene hydroperoxide is a very effective catalyst agent and it is preferred to use this as it can be stored for a long time without any decomposition or other decomposition occurring. However, contact between the catalyst material and the reducing agent prior to actual use should always be avoided to eliminate or at least reduce to a minimum any possibility of an accidental loss of catalyst.

Increased rates of polymer loading can generally be achieved by using increasing amounts of catalyst materials within the ranges indicated above. This is shown by the following results which were obtained by treating samples of human hair with methyl methacrylate. The reduction was in each case carried out for 10 minutes using a 6% aqueous ammonium thioglycollate solution

with a pH of 9. The reducing solution was used in an amount of 20 ml per gram hair sample. The treatment with the oxidizing solution

was carried out in the manner indicated in connection with examples 17-21. The results obtained are reproduced in the following table:

It appears that a very favorable percentage grafting can be achieved despite the use of a time of the order of only 10 minutes for the reduction treatment. It also appears that a relatively small increase in the amount of catalyst used leads to a considerable increase in the rate of polymer grafting. By therefore increasing the concentration of cumene hydroperoxide from 1 to

4 ml Per 100 ml of solution, it was possible to achieve a corresponding

increase in the percentage grafting from 4.96 to "7.5, i.e. an approx.

4 times increase. These figures are of the greatest importance due to the reduced times for the reduction treatment. The rate of polymerization and grafting is clearly very sensitive and dependent on the amount of catalyst used. It is left of it

of greatest importance is that such highly advantageous rates for the uptake of polymer can be achieved at room temperature.

As shown in examples 1 - 16, the type of solvent used in the reduction solution is of decisive importance and strongly influences the achievable speed of the graft polymerization in the final oxidation step. It will be readily apparent from the following examples that the same applies to the type of solvent material used in the monomer-containing oxidizing solution. This is evident from the following examples which indicate the results obtained when treating samples of human hair with methyl methacrylate. The reduction and oxidation treatments corresponded to those indicated in the above examples. It appears that the solvent used for the experiments comprised ethyl alcohol, the remainder being water.

It is clear from the above results that the use of organic solvent in increasing amounts leads to reduced polymerization rates. It will also be understood that the relationship between the concentration of organic solvent and the corresponding polymerization rate is critically dependent on the type of monomer material used. A given monomer component can thus withstand large amounts of organic solvent without any adverse effects occurring. the rate of polymerization and grafting. It can generally be assumed that the polymerization rates will decrease if the monomer material used is light and relatively unlimitedly soluble in the selected organic solvent. However, such parameters can be easily determined for a given case. If it should thus be desirable to have lower inoculation rates, this may well justify the use of increasing amounts of organic solvent to achieve this.

Example 3 0

A 22 g sample of DM-36 hair was reduced for 5 minutes with 440 ml of an aqueous solution of 6% ammonium thioglycollate with a pH of 9. The hair was left rinsed with water and then treated for 1 hour at 24°C with 440 ml of a solution consisting of 40 g of itaconic acid, 20 ml of cumene hydroperoxide, 200 ml of ethanol and water up to a volume of 500 ml.

The hair was then rinsed and dried arbitrarily. The hair contained 22.4% itaconic acid. It was braided and then thoroughly moistened and hung straight with weights until dry. The hair was very straight. It was again well moistened and wrapped around glass rods and dried in this form. Very tight curls were obtained with essentially the same shape as the windings around the glass rods. The curled hair was then conditioned at 85% relative humidity and had the following percent curl retention after the indicated times:

The hair was then subjected to four sets of treatments which each included moisturizing, straightening, drying, moisturizing, curling and drying.

In all cases, the hair retained its "fixed" shape after drying and even after a strong and prolonged exposure to high humidity (60-90% relative humidity).

Untreated DM-36 hair that had been well moisturized and curled initially did not have the same degree of physical shape after the glass rods as the treated hair, but more importantly, after being exposed to high humidity (85 %) ,.. the curl retention was as follows:

It was a further notable characteristic of the treated hair that the straightened hair remained substantially unchanged under highly humid conditions while untreated hair "frizzed".

Example 30A

Example 3o was repeated, but using the indicated monomers and amounts instead of 40 g of itaconic acid.

1. 10 g of itaconic acid

2. 15 g methylenemalonic acid

3. 50 g citraconic acid

4. 30 g of maleic acid

5. 12 ml/100 ml ethyl acrylate

6. 6 ml/100 ml vinyl chloride

7. 25 g of lauryl methacrylate

The same good results as in example 30 were obtained.

Example 30B

Example 30 was again repeated, but with the following treatments: 1. 200 ml of ethanol was replaced by 100 ml of acetone. 2. the peroxide was replaced with the same weight of di-tert.butyl peroxide. 3. the peroxide was replaced with the same weight of potassium persulfate.

Example 31

A 20.8635 g sample of DM-36 hair was reduced for 5 minutes with 400 ml of ..a 6% aqueous solution of ammonium thioglycollate

with a pH of 9. The hair was rinsed well with water to remove the thio-glycollate and treated with the following solution at approx. 24°C:

32 g itaconic acid, 16 ml cumene hydroperoxide, 160 ml ethanol

and deionized water up to a volume of 400 ml.

The treated hair was rinsed with water and dried. Dry weight was 24.4543 g, and this indicated a weight increase of 17%.

Six braids of the treated hair were made, of which two

. was treated with 0.1 molar sodium citrate at a pH of 9.5 and two with 0.1 molar CaSO^'. All six were rinsed with water and wrapped around rods in the same way as in example 30. The four finish lead braids (2-citrate and 2-CaSO 4 ) and the other two itaconic acid treated braids and two untreated hair braids were conditioned at one relative humidity of 85% and the percentage curl retention noted as above. The results were:

The above results show that the hair treated with itaconic acid had a very good shape stability under high humidity conditions, that the braids post-treated with calcium sulphate were somewhat more shape stable and that the untreated hair had little stability. Hair post-treated with citrate shows that this is a means of relaxing the curls (shape stability). A further treatment of the citrate-relaxed braids with calcium sulphate restores the pre-retention properties so that they become similar to those originally obtained by the above-mentioned treatment with calcium sulphate.

Of suitable relaxation agents which have proven to be usable and to provide a good effect, mention may be made of the group of polyacids in general and derivatives thereof, and in particular the water-soluble salts of citric acid, ethylenediaminetetraacetic acid, nitriletriacetic acid, water-soluble phytates, e.g. sodium and potassium phytate, water-soluble salts of ethane-1-hydroxy-1,1-diphosphonates, water-soluble salts of methylenediphosphonic acid (e.g. trisodium and tripotassium salts), water-soluble salts of polymers and copolymers of itaconic acid, aconitic acid, maleic acid, methylenemalonic acid in muconic acid citraconic acid.

Besides the above-mentioned calcium sulphate, other water-soluble, polyvalent metal salts can be used for "fixing" the hair. The preferred salts are salts of the group IIA metals. The anion is not of decisive importance as long as the salt is sufficiently soluble in the treatment bath. The preferred anions are sulphate, nitrogen, halogen and the lower fatty acids, e.g. formate, acetate and propionate etc.

The distinctive shape stability of the hair treated by the present method is also apparent from the following example.

Example 32

Four braids were treated with monomer in the same way as in example 31. Two of the braids were "fixed" in straightened form by drying them with suspended weights. The other two braids were treated with calcium sulfate as in example 31 and also "fixed" in straightened form.

Two additional, but untreated, braids were well moistened

and also dried in straightened form. Finally, a pair of braids that had been treated with a commercially available home perm while wrapped around glass rods were well moistened after complete "fixation" and also hung straight with an attached weight. After drying in straightened form, all eight braids were conditioned at a relative humidity of 85%. The four braids that had been treated by the present method remained essentially straight. The untreated hair curled somewhat and the permed hair curled even more. This shows the wide applicability of and the shape stability achieved by the present method.

Example 33

Eight 2 g braids were prepared from 16 g of DM-36 hair. Two were used for control (1 and 2), and the other six were reduced

with 20 ml of a 6% aqueous ammonium thioglycollate solution with a pH of 9 per g hair. They were then thoroughly washed with water and treated with preparations as follows:

Braids 3-6 were treated for 1 hour and 7 and 8 for 30 minutes, all at 24°C. The eight braids were then immersed in water and wrapped around glass rods.

The braids were dried overnight at a relative humidity of 60% and then examined at a relative humidity of 85% at intervals of 0.5 - 24 hours. The average percentage curl retention for each pair is given below.

The very good retention properties can be seen from the above.

" Example 34

To further show the very good qualities of it

treated hair, the braids according to example 32 (in straightened form) were again dipped in water and again wrapped around rods. The percentage curl retention at 85% relative humidity is given below.

Example 3 5

The eight braids according to Example 33 were again immersed in water to remove the curl and then again curled on glass rods at a relative humidity of 60%. The percentage curl retention at 85% relative humidity was as follows:

Example 36

The eight braids according to example 35 were washed with shampoo with 1 ml of HALO/2 g of hair, rinsed with water and straightened (with a weight of 50 g/braid) overnight at a relative humidity of 60%. The braids were then exposed to a relative humidity of 85% for 24 hours and the percentage shrinkage measured. The results were:

Example 37

The braids according to example 36 were again curled first by immersion in water and then winding around glass rods and drying overnight at 60% relative humidity. They were then exposed for 24 hours to a relative humidity of 85% and the percentage curl retention measured. The figures are reproduced in the table below.

The repeated ability of the braids treated by the present method to be able to curl after repeated treatments including straightening and washing with shampoo is clearly shown here.

Keratin-containing materials which have been exposed to conditions which tend to be damaging are generally more likely to give more favorable polymerization reactions, i.e. faster grafting rates. This can possibly be explained

in that the damaged keratin fiber e.g. is more porous, and this leads to a stronger penetration of reagents into the fiber mass. In connection with e.g. human hair, the term "damaged" used herein shall therefore denote e.g. bleached hair and permanently curly hair etc. It has thus always been shown that a given hair sample's adaptation to the present method can be improved by e.g. subjecting the sample to one or more previous bleaching treatments, as more treatments usually lead to more favorable results. This is shown in the following examples which relate to results obtained by grafting methyl methacrylate onto bleached hair. The reduction of the hair sample was in each case carried out for 10 minutes

using a reducing solution comprising 5% sodium bisulphite in a mixed solvent system of ethanol (45%)

and water. The reduction solution was used with a volume of approx.

10 ml per gram hair sample. The treatment with the oxidizing solution was carried out for 30 minutes at room temperature using 20 ml of oxidizing solution per gram hair sample.

It will be seen that hair that was only exposed to a single prior bleaching treatment had a 50% increase in the amount of grafted polymer compared to a control sample of unbleached hair. Moreover, a further improvement in the percentage grafting was achieved with increasing number of previous bleaching treatments.

Similar increases of the grafted polymer amount were obtained

by repeating the treatment described above using hair samples that had been permanently curled. In Examples 43-45

the procedure used was as follows: the reduction was carried out in each case for 20 minutes using a 5% solution of sodium bisulphite in a solvent system of ethanol (45%)

and water. It was used approx. 10 ml reduction solution per gram hair sample. After rinsing, the oxidation step was carried out for approx. 30 minutes at room temperature using 20 ml of monomer solution per grams of hair. The results obtained are reproduced in the following table:

It is clear from the above results that

considerable increases in the amount of grafted polymer were achieved when treating permanently curly hair, and an approx. 8-fold increase in relation to hair that had been pre-treated only once. As indicated above, it appears that the rates of polymer grafting can be attributed to the increased porosity of pre-damaged hair.

In each of the following examples, human hair was treated with the preparation indicated in the following table, the figures being based on parts by weight, for 30 minutes at room temperature. Each of the hair samples had previously been reduced with a 6% thioglycol late solution with a pH of approx. 9.

In examples 38-51, the general method according to examples 1-16 was used.

The amount of polymer grafted onto the hair fibers in each case was favorable compared to the results given in the previous example. Moreover, the results obtained can be taken as an indication of the relatively better effect of the initiators soluble in organic solvents, since initiators of the water-soluble type do not give quite as greatly increased rates for polymer grafting.

As indicated above, the use of water-soluble halide salts in the monomer solution may be advantageous. This is shown in the following examples where samples of human hair each weighing 1-0.003 g were used. In each case, the hair sample was subjected to a reduction treatment for 15 minutes with an aqueous solution of ammonium thioglycollate (6%) with a pH of 9. After the reduction treatment was over, the hair sample was rinsed well to remove remaining reducing agent. Then the reduced hair sample was treated with a monomer solution of the indicated composition for 1 hour at a temperature of 40.6°C. About. 27 ml of monomer solution was used per g treated hair. The amount of grafted polymer was calculated as the percentage increase in dry weight after drying for 12 hours over calcium chloride in a drying box. The results obtained are reproduced in table 8.

Similar results to those indicated above were obtained

obtained by repeating the described procedure, but by using such materials as dibutyl peroxide, tert.butyl hydroperoxide, benzoyl peroxide, peracetic acid and hydrogen peroxide instead of cumene hydroperoxide. As indicated above, the use of certain of the above-mentioned initiators proved to be particularly advantageous due to a better stability and easier handling. Instead of potassium persulphate, similar results can be obtained by using sodium persulphate, ammonium persulphate and persulphuric acid. In any case, it should be noted that the initiator material chosen for use can be any of those commonly used for polymerization of vinyl-type monomers initiated with free radicals. It will of course be understood that special monomer compounds

may well prove to be more effective to use only in conjunction with a limited number of types of initiator compounds. Such trade-offs can, however, be easily arrived at by the user for a given case.

le to thereby determine the optimal embodiments of the method.

Moreover, the use of keratin-containing materials other than human hair, especially wool, synthetic keratin fibers and animal hair, leads to similar results. The present method has proven to be exceptionally well suited for use in connection with the latter materials as a wide range of different modification treatments are possible for achieving changes in the receptivity to dyes and in the grip etc. One or more of a number of different properties of keratin-containing substrates can thus be effectively modified using the present method. An investigation has thus suggested that the moisture content of the keratin material chosen for the treatment at equilibrium can be changed with a corresponding regulation of the grafted amount of polymer. As a rule, it has happened that the percentage

elle amount of water vapor absorbed by hair grafted with polymer, e.g. polymethyl methacrylate, decreases by an amount approximately corresponding to the percentage amount of grafted polymer.

Example 58

This example shows the use of ammonium persulfate

during the treatment process.

A 1 g sample of DM-3 6 hair was reduced for 3 minutes with

20 ml of a 6% aqueous ammonium thioglycollate solution with a pH

of 9. The hair was then thoroughly rinsed with water and then treated for 1 hour at 24°C with 20 ml of a solution consisting of 6 g of itaconic acid, 4 g of ammonium persulphate, 10 ml of ethanol and deionized water up to a volume of 100 ml .

The treated hair had essentially the same properties

creates as described in the above examples.

Claims (4)

1. Procedure for treating hair to give it a desired physical shape, characterized by the hair being is treated with a reducing agent to convert at least a portion of the disulfide bonds in the hair to mercaptan bonds, the remaining reducing agent is removed from the hair by rinsing, the hair is treated with an oxidizing solution comprising a peroxide catalyst material and an olefinically unsaturated monomer compound containing at least one group of the formula or an olefinically unsaturated compound of the formula wherein each of the R groups is independently hydrogen, halogen, alkyl, alkoxy, aryl, acyl, carboxy, carbaloxy or carboxamide, and which can be polymerized in the presence of the peroxy initiator, whereby the monomer is graft polymerized onto the hair which is then rinsed to-,... to remove unreacted monomer and initiator, given the desired physical form in the wet state and dried with the desired physical form after which the hair is re-moistened with complete loss of shape retention, re-laid in any desired form and dried, one or more times. 2. Method according to claim 1, characterized in that the hair is relaxed with a mixture of water and a water-soluble salt consisting of citrates, ethylenediamine tetraacetates, nitrile triacetates, phytates, ethane diphosphonates or methylene diphosphonates or a water-soluble salt of polymers of unsaturated organic acids consisting of itaconic acid , aconitic acid in maleic, methylenemalonic, muconic or citraconic acid. 3. Method according to claim 1 or 2, characterized in that the water used for relaxing the hair also contains a water-soluble salt of a metal from group IIA in the periodic table. 4. Method according to claim 3, characterized in that calcium sulfate is used as the water-soluble salt.