Note: Descriptions are shown in the official language in which they were submitted.
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Hair Shaping Agents
This invention relates to a process for shaping hair by reductive
cleavage and oxidative restoration of disulfide bonds in the hair's keratin,
in
which a preparation in the form of a fine-droplet oil-in-water emulsion
containing a limited quantity of hydrophilic emulsifiers is used to carry out
the keratin reducing step.
Hair shaping preparations are essentially understood to encompass
permanent wave preparations and hair smoothing preparations. Cold
permanent wave preparations contain reducing agents which reduce the
disulfide bonds in the hair's keratin to mercapto groups. They may also
contain strong alkalis, for example alkali metal hydroxides, ammonia and
alkanolamines and other keratin-swelling chemicals such as, for example,
urea, guanidine or imidazole. Hair smoothing preparations also contain
strong keratin swelling agents, generally in combination with keratin
reducing agents. The hair may be mechanically shaped, for example
wound onto rollers, before or after the treatment with these chemicals. The
shape is fixed when some of the disulfide bonds of the keratin are re-
established by mild oxidation.
However, the effect of the keratin reducing agent is not totally
reversible and leads to some unwanted side effects. Since not all the
disulfide bonds are re-established, the durability of the shape (known as
curl retention) is far from optimal and the strength of the hair fibers is
reduced. The outer scaly layer of the hair known as the cuticula is also
attacked so that the hair becomes rough and difficult to comb and has a
dull feel.
Accordingly, there was a need to minimize the unwanted side effects
by suitable formulation of the permanent wave preparations. This can be
done, for example, by adding swelling agents to loosen the hair structure
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so that the active chemicals are able to penetrate more quickly into the
interior of the hair. Another method of increasing the effectiveness of the
active chemicals lies in the galenic preparation, for example as a
microemulsion in accordance with WO-A-94124987. However. this does
involve the use of relatively large amounts of hydrophilic surfactants which
can contribute towards irritation of the skin.
It has now been found that the very fine-droplet emulsions
obtainable by the phase inversion process with mean droplet sizes of less
than 200 Nm, which can be produced with limited quantities of hydrophilic
emulsifiers, can be used surprisingly effectively as carriers for hair shaping
preparations and have a particularly favorable influence on the properties
of the shaped hair.
Accordingly, the present invention relates to a process for
permanently shaping hair in which, before or after mechanical shaping, the
hair is treated with a keratin reducing agent, rinsed and fixed with an
oxidizing agent, characterized in that a fine-droplet oil-in-water emulsion
containing at least 1 % by weight of a water-soluble keratin reducing agent
and at least 1 % by weight of an emulsified oil or fatty component with a
mean droplet size of less than 200 nm and less than 0.4 part by weight of a
hydrophilic emulsifier, based on 1 part by weight of the oil or fatty
component, is used for keratin reduction.
Keratin reducing substances selected from the group of mercapto
compounds, phosphines and sulfates are used as the water-soluble keratin
reducing agents. Suitable mercapto compounds are the water-soluble salts
of mercaptocarboxylic acids containing 2 to 4 carbon atoms such as, for
example, thioglycolic acid and thiolactic acid, i.e. for example ammonium
thioglycolate, sodium or potassium thioglycolate, monoethanolamine
thioglycolate or the corresponding thiolactates, and cysteine and
cysteamine.
Preferred sulfites are the alkali metal, ammonium and
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alkanolammonium salts of sulfurous acid and disulfurous acid, for example
sodium sulfite (Na2S03) or sodium disulfite (Na2S205).
1 to 20% by weight of a keratin reducing chemical selected from the
group of mercapto compounds, phosphines or sulfites is preferably present
as the keratin reducing agent.
The present invention also relates to a preparation for carrying out
the keratin reducing step of a process for the permanent shaping of hair in
the form of a fine-droplet oil-in-water emulsion containing at least 1 % by
weight of a water-soluble keratin reducing agent and at least 1 % by weight
of an emulsified oil or fatty component with a mean droplet size of less than
200 nm and less than 0.4 part by weight of a hydrophilic emulsifier, based
on 1 part by weight of the oil or fatty component.
The oil or fatty components are understood to encompass any
water-insoluble lipids, but preferably those which are stable to hydrolysis,
even in strongly basic media. Suitable oil or fatty components are, for
example, paraffins (Vaseline), paraffin oils, squalane, fatty alcohols (for
example cetyl and stearyl alcohol), 2-octyl dodecanol, dialkyl ethers, etc.
Less suitable are triglycerides and other ester oils.
In terms of stability in the strongly basic medium and suitability for
the preparation of the fine-droplet emulsion, particularly preferred oil
components are low molecular weight liquid hydrocarbons containing 8 to
36 carbon atoms, dialkyl ethers containing 12 to 36 carbon atoms and
mixtures of these components. Suitable low molecular weight
hydrocarbons are, above all, branched hydrocarbons or synthetic products
such as, for example, 1,3-di-(2-ethylhexyl)-cyclohexane which is marketed
under the name of Cetiol~ S. Suitable dialkyl ethers are, for example, cetyl
isopropyl ether, stearyl methyl ether or symmetrical dialkyl ethers such as,
for example, di-n-octyl ether which is marketed under the name of Cetiol~
OE. The oil components are preferably present in quantities of 5 to 20% by
weight.
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Suitable hydrophilic emulsifiers are, for example, anionic,
zwitterionic, ampholytic or cationic surfactants, but preferably nonionic
emulsifiers with an HLB value above 10. The HLB value is a value which
may be experimentally determined by the emulsion comparison method
and which, in very approximate terms, may be estimated from the equation
HLB = 0.2 ~ (100 - L), where L is the percentage by weight of the lipophilic
groups, i.e. for example the fatty alkyl or fatty acyl groups, in % by weight
in
the emulsifier molecule. Preferred nonionic emulsifiers are, for example,
fatty alcohol polyglycol ethers which may be obtained by addition of more
than 1 part by weight of ethylene oxide onto 1 part by weight of a fatty
alcohol containing 12 to 22 carbon atoms. Examples of such emulsifiers
are the addition product of 10 moles ethylene oxide (EO) onto behenyl
alcohol, which is marketed under the name of Mergital~ B10, or the
addition product of 12 moles ethylene oxide onto a technical cetyl/stearyl
alcohol cut which is marketed under the name of Eumulgin~ B1. Fatty
alcohol polyglycol ethers with HLB values of 10 to 18 are particularly
suitable.
The droplet fineness of the emulsion according to the invention can
be achieved, for example, by the PIT method by using nonionic emulsifiers
in the preparation of the emulsion and heating the emulsion beyond the
phase inversion temperature during its preparation. The PIT method is
described, for example, in DE 40 10 393 A1 for polar oil components. For
hydrocarbons and dialkyl ethers, which are preferred for the emulsions
according to the invention, the choice of the HLB value is less critical and
the use of co-emulsifiers may optionally be dispensed with.
One particular advantage of the preparations according to the
invention for carrying out the keratin reducing step of the permanent wave
process is that the emulsifier content can be kept very low, a quantity of
less than 0.4 part by weight per part by weight of the oil or fatty
components being sufficient to achieve the droplet fineness according to
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the invention.
The phase inversion process generally gives very fine-droplet
emulsions with mean particle sizes of 50 to 200 nm, i.e. the emulsions are
not yet clear microemulsions which have a mean droplet size below 50 nm
and which should be free from particles above 100 nm in size in order to
appear completely transparent.
Typical PIT emulsions suitable for the purposes of the invention are
opalescent and appear bluish in reflected light and brownish in transmitted
light. In particularly favorable cases, however, clear or transparent
microemulsions can even be formed.
By virtue of the effectiveness of the preparations according to the
invention in reducing keratin, the pH value can be kept relatively low, i.e.
around the neutral point to at most pH 9, without any reduction in curl
retention. As can be seen from the Examples, curl retention is distinctly
higher where a fine-droplet emulsion as opposed to an aqueous solution is
used for substantially the same pH value and the same concentration of
reducing agent.
The sensorial properties of the shaped hair, which are highly
unsatisfactory where sulfite or disulfite in particular is used as the keratin
reducing substance, are also distinctly improved by the use of the fine
droplet emulsions according to the invention. The luster, volume,
combability and smoothness of the hair are distinctly increased by
comparison with an aqueous solution of the reducing agent. This applies in
particular to the dry combability of the treated hair which is a measure of
the surface condition of the cuticula.
Besides the emulsified oil or fatty component, the emulsifier and the
keratin reducing agent, the preparations according to the invention may
contain other auxiliaries which improve either the performance properties or
the appearance and the sensorial properties of the preparations or the hair
shaped with them.
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For example, the effectiveness of the keratin-reducing substances
can be enhanced by keratolytic keratin-swelling chemicals which enable
the reducing agents to penetrate more rapidly and more deeply into the
hair structure. Such chemicals are, for example, urea, guanidine,
imidazole, organic amines, for example alkanolamines, or arginine,
glyolethers, glycerol and lower alcohols containing 1 to 4 carbon atoms.
Urea, imidazole or monoethanolamine are preferably used. The effect of
the keratin swelling components is further enhanced by the presence of
suitable alkalizing agents such as, for example, alkali metal hydroxide,
ammonia or ammonium carbonate.
The viscosity of the preparation according to the invention for
carrying out the keratin-reducing step is preferably adjusted so that the
preparation can readily be applied to the mechanically shaped hair, for
example in rollers or curlers, and penetrates into the tresses, but does not
drip off or run onto the scalp. To this end, the viscosity is adjusted to a
value of 1,000 to 10,000 mPa~s (25°C, D = 10/s).
In the absence of special thickening measures, very low viscosity
emulsions with viscosities below 500 mPa~s (25°C, 10 D/s) are obtained
in
the production of emulsions by the phase inversion process. Accordingly,
the preparations according to the invention preferably contain thickeners
for the outer aqueous phase. Suitable thickeners are any water-soluble
natural and synthetic polymeric hydrocolloids, but also inorganic thickeners,
for example layer silicates (e.g. bentonite) or thickening silicas.
Suitable natural thickeners are, for example, agar agar, guar gum,
locust bean gum, pregelatinized starches and pectins; synthetic
hydrocolloids are, for example, the water-soluble cellulose derivatives, for
example carboxymethyl cellulose or hydroxyethyl cellulose, crosslinked
polyacrylic acids, polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene
oxides. Biopolymers, such as xanthan gum and gellan gum, are also
particularly suitable.
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Particularly low viscosity preparations are suitable for use as an
aerosol foam using suitable propellent gases such as, for example,
dinitrogen oxide (N20), dimethyl ether, butane or 1,1,1,2-tetrafluroethane.
Perfumes or odor enhancers, preferably alkali-stable perfume oils
free from aldehydic and hydrolyzable components, are used to mask the
odor.
Other auxiliaries which may be present are, for example, opacifiers,
dyes, buffers, complexing agents and other surfactants, although their total
quantity should not exceed 0.4 part by weight per part by weight of the oil
component.
Finally, the preparations according to the invention may contain
additives for improving dermatological compatibility and hair-care
properties, for example amino acids, protein hydrolyzates, cationic
polymers, silicones, panthenol, vitamin or plant extracts.
The process according to the invention uses typical preparations
known for permanent waving for the other process steps, for example for
the oxidative fixing step. Typical constituents of the aqueous fixing solution
are oxidizing agents such as, for example, hydrogen peroxide or sodium
bromate, surface-active compounds, stabilizers, perfumes and acids, for
example citric acid or tartaric acid, for adjusting a pH of 3 to 5.
The reducing step of the process according to the invention may be
preceded by a pretreatment step using a preparation containing hair-
protecting components, for example cationic polymers or leveling
components such as, for example, glucose or sorbitol.
Similarly, the fixing step may be followed by an aftertreatment of the
hair which is intended to reduce the swelling and to make the hair harder
and more elastic. Corresponding aftertreatment chemicals are, for
example, salts of divalent and trivalent metals, for example calcium or
aluminium salts, preferably of hydroycarboxylic acids such as, for example,
citric acid or tartaric acid.
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Since the aqueous preparations for carrying out the process
according to the invention are applied in immediate succession to the
mechanically shaped hair in rollers or curlers, it is of particular advantage
to
pack the preparations for carrying out the process according to the
invention separately in the quantities adapted to one another and suitable
for a single application in one and the same retail pack. In this way, it is
possible sufficiently safely to ensure, even for non-professional home use
of the process, that the user uses keratin reducing and fixing preparations
optimally adapted to one another in quantity and concentration. In another
variant, a separately packed activator is included in the retail pack of wave
preparation and fixing solution and, before the wave preparation (keratin
reducing chemical) is applied, is combined therewith and leads to an
increase in temperature in the keratin reducing chemical. In this way, the
effect of the wave preparation can be enhanced and the necessary contact
time with the hair can be shortened. The activator used may be a
substance which generates heat with the components of the keratin
reducing chemical, for example by hydration with the water or by partial
oxidation of the reducing agent. Suitable activators are, for example,
hydrogen peroxide or adducts thereof, water-free zeolites or water-free
salts with positive heat of solution, for example magnesium sulfate.
Directions for use included in the pack will help the user to avoid wrong
dosages and misuse.
The invention is illustrated by the following Examples.
Examples
Preparations according to the invention for carrying out the keratin-
reducing step of a permanent wave process were prepared.
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Table 1.
Example 1 2 C
Cetiol~ OE 5.7 5.7 -
Cetiol~ S 5.7 5.7 -
Mergital~ B10 3.0 3.0 -
Structure~ 3001 (30%) 3.0 3.0 -
HS-CH2-COONH4 (50% in water) 20.0 - -
NaZS205 - g.9 6.9
Urea (50% by weight in water) - 30.6 30.6
NH4HC03 7.05 - -
Ammonia solution (25%) 1.68 6.3 3.1
Turpinal~ SL (60%) 0.50 - -
Texapon~ NSO (28%) - 2.7 2.7
Water to 100 to 100 to 100
pH value 8.3 7.3 6.5
Dry combability [mJ] - 196 625
Retention [%] 81 - 95 89
Preparation of products 1 and 2 according to the invention
A fine-droplet emulsion was prepared from the oil components
(Cetiol OE, Cetiol S) and the emulsifier (Mergital B10) and 10 parts by
weight water by the PIT process. After cooling to 40°C, the thickener
was
added. The other components were combined to form an aqueous solution
and mixed with the emulsion.
Preparation of comparison product C
The components were combined to form an aqueous solution.
The following commercial products were used:
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Cetiol~ OE : di-n-octyl ether
Cetiol~ S : 1,3-bis-(2-ethylhexyl)-cyclohexane
Mergital~ B10 : behenyl alcohol poly(10E0)glycol ether
Structure~ 3001 : Acrylates/Ceteth-20-Itaconate Copolymer
Natrosol~ 250 HR : hydroxyethyl cellulose
Texapon~ NSO : fatty alcohol(C~2_~4)poly(2E0)glycol ether sulfate, Na
Turpinal~ SL : 1-hydroxyethane-1,1-diphosphonic acid
Performance Tests
1. Curl retention
27 cm long hair tresses weighing 0.6 g were laid in zigzag waves on
a standard wave board and treated in this position with the permanent
wave preparation, rinsed, treated with a fixing solution and rerinsed. The
compositions of Examples 1 and 2 and comparison products 1 C and 2C
were used as the permanent wave preparations while an aqueous solution
of 3.5% by weight potassium bromate, 7% by weight fatty alcohol
polyglycol ether sulfate Na salt, 5% by weight cocofatty acid
diethanolamide, 0.15% by weight tartaric acid, 0.3% by weight perfume oil
and 1 % by weight sodium chloride was used as the fixing solution.
After drying, the tresses were removed from the wave board. The
length of 6 amplitudes of the wave defined the wave value. A weight of 50
g was then attached to the hair tresses which were then hung vertically for
60 minutes in a water-filled cylinder. After removal of the weight, the length
of 6 amplitudes was again measured. Curl retention is calculated using the
equation Cr (%) = 100 ~ (I - Iso) / (I - lo) where
I = length of the 6 amplitudes in the straightened state
to = length after permanent wave treatment
Iso = length after 60 mins. under load
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2. Dry combability
Twenty hair tresses (15 cm long, weight 2 g) were treated with the
permanent wave solution, rinsed, fixed, rinsed and dried without
mechanical shaping. The tresses were then stored (conditioned) for 12
hours at 30°C/20% relative air humidity and combed. Ten combings were
then carried out in a fully automatic apparatus and the combing work
involved was measured.
The dry combability value [in mJJ is the mean work integral over all
20 tresses.
