Hair styling process using UV-visible radiation.
The UV-visible light radiation method addresses the limitations of existing hair shaping methods by using moderate-power UV radiation and mechanical tension to achieve effective shaping with reduced damage and shorter treatment times.
Patent Information
- Application Number
- FR2023005483
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-06-01
- Publication Date
- 2025-11-07
- Estimated Expiration
- 2043-06-01
AI Technical Summary
Existing hair shaping methods, such as heated straightening irons and chemical treatments, cause damage and require long treatment times, while low-power UV exposure is ineffective and high-power UV exposure is harmful.
A hair shaping process using moderate-power UV-visible light radiation (280-650 nm, 2-50 W/cm²) with mechanical tension, eliminating the need for high chemical concentrations and additional heat sources.
Achieves effective hair shaping with reduced damage and shorter treatment times, suitable for all hair types, including light hair, without the need for additional heat or chemical treatments.
Smart Images
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Abstract
Description
Title of the invention: Method for shaping hair by UV-visible radiation.
[0001] The present invention relates to a method for shaping keratin fibers using UV-Visible light radiation. The method is particularly relevant to shaping human keratin fibers, primarily hair. More specifically, the shaping method is a straightening process.
[0002] There are many techniques for achieving hair styling.
[0003] One of the most common methods involves using heated straightening irons (generally called "hair straighteners"). The general design of such devices is well known. These irons allow for straightening hair fibers at high temperatures (between 180 and 230°C) without excessively pulling on the hair fibers, unlike blow-drying. However, to achieve a good straightened look, several passes of the iron are necessary, which significantly increases the treatment time.
[0004] Furthermore, the repeated application of flat straightening clips can sometimes cause degradation of the hair fibers due to the application temperature of the latter.
[0005] Hair straighteners also allow for curling by wrapping the treated strand of hair around the arm or arms of the clamp.
[0006] In order to facilitate and improve the styling that can be achieved with these devices, it is known to associate them with a diffusion of water vapor on the hair (see for example EP2236053B1).
[0007] Chemical processes known as "permanent" methods for long-lasting hair shaping are also known, comprising the application of a reducing composition capable of breaking the disulfide bonds present in the keratin fiber. This method then includes, preferably after rinsing the hair, a second step consisting of reconstituting the disulfide bonds by applying an oxidizing composition called a fixative to the hair. Prior to the application of the reducing composition, the hair may be held under tension using appropriate devices such as curlers or straightened. The reconstitution of the disulfide bonds makes it possible to maintain the hair in the desired shape.
[0008] A second method comprises an anthionization step using a composition including a base belonging to the hydroxide family and capable of transforming disulfide bridges into monosulfide bridges. This type of treatment is mainly used for styling naturally curly hair.
[0009] In order to obtain satisfactory performance in terms of durability of the installation In this form, the compositions used in these chemical treatments can contain relatively high concentrations of active chemicals (reducing agents or hydroxide compounds, for example). For instance, thioglycolic acid may be used in some compositions at mass concentrations between 6 and 11%, and sodium hydroxide at 2%. Products containing thioglycolic acid have an unpleasant odor, which may be present during application and can also persist on the hair after the treatment. Furthermore, the treatments described above can lead to irreversible hair damage induced by changes in the intrinsic properties of the hair fiber. These treatments can also irritate the scalp due to their relatively high concentration of active chemicals. It is also known that heat is applied during the treatment to activate the processes.The heating stage is generally carried out at a temperature between 80 and 120°C for a duration of approximately 20 to 30 minutes. This heating stage is therefore likely to cause even greater damage to the hair.
[0010] Heating energy can be supplied by various means, and for example, by exposing hair to infrared radiation (see for example FR2941600A1) or microwaves (see for example WO2013183021A1).
[0011] Among the energy sources used in hair treatments, exposure to UV radiation is also known.
[0012] US patent 56053180A describes hair styling devices, such as combs, curling irons, and hairbrushes, equipped with UV diodes. The UV radiation is intended for cleaning and disinfection and is not intended to contribute to the actual hair treatment. The radiation power is not described; however, in disinfection applications, exposure to UV-C at a power of less than 100 mJ / cm² is considered more than sufficient to destroy the vast majority of bacteria.
[0013] Document DE102005059936A describes a hair treatment process comprising shaping the hair and applying a reducing composition (opening disulfide bonds) before exposing the treated hair to UV radiation. After exposure, an oxidizing composition (re-establishing disulfide bonds) is then applied to fix the hair. It is simply stated that UV light assists the phenomenon of disulfide bond reduction and allows for a reduction in treatment time compared to a "conventional" perm.
[0014] UV exposure is also used in other hair treatment processes such as those described in particular in documents US5246019A, WO2015165949, WO2020234311 and WO2007048473, relating to the bleaching and / or coloring of hair, and WO2017108767, WO2007048472A1 relating to the application of composition of photopolymerizable skincare products.
[0015] In view of the limitations mentioned above, there is a permanent need to improve the processes for shaping keratin fibers such as hair, particularly human hair.
[0016] To this end, the present invention relates to a process for shaping keratin fibers, in particular human keratin fibers, especially hair, comprising the steps aimed at:
[0017] - apply mechanical tension to the keratin fibers to be treated,
[0018] - expose said keratin fibers to light radiation having a maximum emission in a wavelength range between 280nm and 650nm,
[0019] the process being characterized in that the keratin fibers to be treated receive an energy illumination greater than or equal to IW / cm2 and less than or equal to 50 W / cm2.
[0020] Thus, unlike the processes described above, which employ very low-power UV exposure to aid the action of conventional reducing agents, and unlike the processes that, conversely, require high-power UV exposure (crosslinking, bleaching), it has been discovered that exposure to moderate-power UV-visible light radiation allows for the shaping of keratin fibers. Such power is low enough to limit the potentially negative effects of radiation on hair (lightening, damage) and high enough to eliminate the need for high concentrations of disulfide bond reducing agents.
[0021] It is known from the article "Direct Ultraviolet Laser-Induced Reduction of Disulfide Bonds in Insulin and Vasopressin," ACS Omega 2020, 5, 7962-7968, that it is possible to reduce disulfide bonds in insulin and vasopressin using UV laser radiation. However, this document does not mention the possibility of achieving such a reduction in keratin fibers for the purpose of shaping said fibers. Furthermore, it is hardly conceivable to use such powerful laser radiation for shaping hair.
[0022] The illuminance power implemented in the process which is the subject of this application can be obtained by the use of LEDs, in particular UV LEDs.
[0023] Without wishing to be bound by any theory, although the power of the targeted radiation does not a priori allow for inducing a change in the disulfide bonds, the applicant believes that the shaping, and in particular the straightening, can be explained at least partially by the electronic transitions of the hair's melanin due to the absorption of the electromagnetic wave. Heat is then released from the core of the hair to its exterior. This heat is internal to the hair and one does not consider more the classic scheme of a hair straightener of the type thermal conduction of plates towards the inside of the hair.
[0024] The generated heat makes it possible to act on the hydrogen bonds, which are strongly present in the keratin of the hair, bonds which also contribute significantly to the hold and shape of the hair.
[0025] It should also be noted that, unlike styling processes using infrared radiation, the use of UV-visible radiation makes it possible to achieve an effect even on light hair, as the melanin present is sufficient to absorb an amount of radiation capable of generating sufficient heat. Thus, although it can be used on all hair types, the present process is particularly suitable for so-called "light" hair with a tone level above 6 (dark blonde), and especially above 8 (light blonde).
[0026] Preferably, the keratin fibers to be treated receive an energy illumination greater than or equal to 2 W / cm2, better 4 W / cm2, even better 6 W / cm2.
[0027] Preferably, the keratin fibers to be treated receive an energy illumination less than or equal to 25 W / cm2, better 12 W / cm2, even better 8 W / cm2.
[0028] Better results were obtained for illuminance values between 6 and 8 W / cm2.
[0029] The process which is the subject of this application can be implemented with different types of tools and in particular with the aid of a plier-type tool as described in the aforementioned application WO2020234311A1.
[0030] Advantageously, the energy illumination stage is the main heat source, or rather the only heat source, and the process is implemented without an additional heat source. In particular, the process is implemented without a heating stage by thermal conduction (heating plates) and / or without additional radiant heating (microwave or infrared radiation, for example) and / or without convective heating (blowing hot air, for example).
[0031] Preferably, the keratin fibers to be treated are moved in front of an optical illumination window so as to be subjected to a total fluence greater than or equal to 10 J / cm² and less than or equal to 100 J / cm² per pass. Of course, the keratin fibers can also be held fixed relative to the UV light source and placed in an illumination chamber. However, moving the fibers relative to the light sources allows for better control of their exposure and ensures that each portion of the fibers receives substantially the same treatment. This also allows for the use of more ergonomic and compact equipment for implementing the process.
[0032] Preferably, the keratin fibers are moved in front of the light sources at a relative speed less than or equal to 10 cm / second, preferably less than 2cm / second. Preferably, the speed of movement is greater than or equal to 0.5 cm / second.
[0033] According to a first embodiment the process comprises a single step of exposure to light radiation.
[0034] According to a second, preferred embodiment, the method comprises a plurality of light exposure steps, the steps being repeated successively. The exposure step can be repeated from 2 to 10 times, preferably from 2 to 5 times. The number of passes increases the total fluence received by the fibers while maintaining a relatively small illumination window in a compact device.
[0035] Preferably, the wavelength of the maximum emission of the light radiation is greater than or equal to 315nm, better greater than or equal to 350nm, or even greater than or equal to 370nm.
[0036] Preferably, the wavelength of the maximum emission of the light radiation is less than or equal to 650nm, better less than or equal to 500nm, or even less than or equal to 460nm.
[0037] Advantageously, the wavelength of maximum emission of ultraviolet radiation is between 370 and 460 nm.
[0038] Preferably, the keratin fibers to be treated are put under mechanical tension with a force greater than or equal to 0.1N, preferably greater than or equal to IN, better greater than or equal to 15N.
[0039] Preferably, the keratin fibers to be treated are put under mechanical tension with a force less than or equal to 1000N, preferably less than or equal to 30N, better less than or equal to 20N.
[0040] Advantageously, the keratin fibers to be treated are put under mechanical tension with a force between 1 and 30 N, better between 15 and 20 N.
[0041] According to a first embodiment, the treatment process is a smoothing process, and the keratin fibers to be treated are placed under tension in a substantially straight line. This tensioning can be achieved, in particular, using a comb, preferably integrated, either permanently or in a removable manner, into a treatment apparatus comprising suitable light sources for implementing the process. Alternatively or in addition, the keratin fibers can be placed under mechanical tension by pinching them between treatment plates of the apparatus. For this purpose, the treatment apparatus comprising the suitable light sources may be in the form of a clamp comprising two arms articulated relative to each other and capable of adopting a spread configuration allowing the insertion of a strand of keratin fibers to be treated and a closed configuration for pinching said keratin fibers to be treated.For a more detailed description of the type of device that can... to be used, reference can be made to request WO2020208077.
[0042] According to a second embodiment, the treatment process is a looping process, and the keratin fibers to be treated are placed under tension and wound. The keratin fibers to be treated can, in particular, be wound onto curler-type accessories.
[0043] Alternatively, they can also be wrapped around the arms of a clamp-type device as previously mentioned, as can be done on the arms of a hair straightener.
[0044] Advantageously, the process is carried out without any composition, and in particular without any composition capable of reducing disulfide bonds in the keratin fibers to be treated. If a composition is applied beforehand to the keratin fibers to be treated, said composition comprises less than 6% by mass of ingredients capable of reducing disulfide bonds, and in particular less than 6% of thiol compounds such as thioglycolic acid. Preferably, said composition comprises less than 1% by mass of ingredients capable of reducing disulfide bonds, or better yet, contains no such ingredients.
[0045] Preferably, said composition also comprises less than 1% by mass of alkali agents of the hydroxide / soda type, better does not comprise such agents.
[0046] According to a first embodiment, the process is carried out on keratin fibers to be treated which have been previously moistened with an aqueous composition, the aqueous composition consisting essentially of only water.
[0047] Preferably, the process is carried out on keratin fibers not previously moistened (so-called dry hair, i.e. substantially in equilibrium with ambient humidity, or even slightly dehydrated and more particularly either that have not been washed with water at least two hours before the implementation of the process, or dried with a hair dryer).
[0048] Advantageously, the process does not include a step of applying an oxidizing composition suitable for restoring disulfide bonds.
[0049] Thus, preferably the compositions of the invention possibly used before (at most 2 hours before, better at most 12 hours before) and / or during and / or after (at most 2 hours after, better at most 12 hours after) the UV illumination step do not contain agents selected from among oxidizing agents, reducing agents, alkali-type hydroxide agents or coloring agents.
[0050] The illumination step may be followed, in a short period of time, by additional treatment steps. These steps may include, in particular, the application of cosmetic compositions and / or drying. This additional treatment step may take place within a time interval of less than one week, preferably less than 48 hours, and even better, less than 24 hours. Unlike certain treatments such as a hair coloring which is not recommended to be carried out before at least 72 hours, or even a week after a perm, this shaping process can be followed almost immediately by such a treatment without any additional treatment step other than a possible rinsing or washing (preferably without an intermediate washing or rinsing step).
[0051] Conversely, the process can be implemented on keratin fibers that have been previously subjected to a bleaching and / or coloring process less than 2 hours before.
[0052] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which: [Fig.1] is a photograph of a lock of hair before treatment by a process which is the subject of this application. [Fig.2] is a photograph of the lock of hair from [Fig.1] after treatment by the process which is the subject of this application. [Fig.3], [Fig.4], [Fig.5] present results obtained for another reference wick. [Fig.6] and [Fig.7] present results obtained for a reference strand that had previously undergone a bleaching process. [Fig.8], [Fig.9], [Fig.10] show results obtained on the strand of [Fig.6] which was subjected to a coloring step subsequent to the bleaching step. [Fig.11] and [Fig. 12] show results obtained with a reference strand that has undergone double bleaching.
[0053] Figure 1 shows a 2.7g strand of Caucasian hair with a length of 27 cm before treatment according to the process of this application. The hair strand has waves. The keratin fibers forming the strand are subjected to mechanical tension tending to keep them straight (smooth) and are subjected to a UV illumination step having a maximum emission between 385 nm and 405 nm so that the fibers receive an illumination power of 6 watts per cm².
[0054] To achieve this, the strand of hair is moved relative to a lighting device at a speed of approximately 1 cm per second for an optical window of 2 cm. The strand is exposed to light for 2 seconds per centimeter. The fluence value is therefore approximately 12 J per cm² per pass.
[0055] The total illuminance power is obtained by subjecting the wick to several passes (4 passes) through the illuminating device so that the total fluence received by the wick is substantially equal to 48 J / cm2.
[0056] Figure [Fig. 2] shows the hair strand after treatment.
[0057] It was found that four passes made it possible to obtain on the strand a degree of straightening substantially equivalent to that which can be obtained with a straightener set at 210°C. The straightened strand is, however, less compact and retains a greater width at mid-height.
[0058] It should be noted that the present straightening process also offers less hold, and some curling is observed even after washing / shampooing. Hold in an atmosphere with 80% relative humidity is also less than with straightening performed using a flat iron set at 210°C. However, considering the aforementioned drawbacks of alternative styling methods, this straightening process represents a particularly attractive solution.
[0059] The following figures show results for other wicks with other parameters. The unspecified parameters are identical to those of the previous example.
[0060] Figure 3 shows another reference strand of slightly wavy Caucasian hair (curl level 4) before processing. The strand has a tone level of 4 (brown).
[0061] Figure 4 shows the smoothing obtained after illuminating the wick of Figure 3 with a wavelength of 385 nm and with an illumination power of 10 Watts per cm². The speed of movement is 2.7 cm per second and 4 passes of the wick are made in front of the illumination sources.
[0062] Figure 5 shows the smoothing obtained after illuminating the wick of Figure 3 with a wavelength of 385 nm and with an illumination power of 16 Watts per cm². The speed of movement is 5.4 cm per second and 5 passes of the wick are made in front of the illumination sources.
[0063] Fig. 6 shows a reference Caucasian hair strand with a degree of curl equal to 4 and an initial tone height equal to 4. The reference strand has also undergone a bleaching treatment using L'OREAL PROFESSIONNEL BLOND STUDIO 9 powder.
[0064] Figure 7 shows the smoothing obtained after illuminating the bleached strand of Figure 6 with a wavelength of 385 nm and with an illumination power of 8 Watts per cm². The speed of movement is 1.3 cm per second and 4 passes of the strand are made in front of the illumination sources.
[0065] Figures 8 to 10 show the smoothing obtained after illuminating the bleached strand of [Fig. 6] with a wavelength of 385 nm and an illumination power of 6 Watts per cm². The travel speed is 1.3 cm per second, and the strand is passed in front of the light sources four times. Before implementing the process, the bleached strands underwent an additional coloring step using a L'Oréal Professionnel Maurel product. More Specifically, the strand in [Fig.8] was colored using MAJIREL 4; the strand in [Fig.9] was colored using MAJIREL 6.66 and the strand in [Fig.10] was colored using MAJIREL 7.43.
[0066] Fig. 11 shows a reference Caucasian hair strand with a degree of curl equal to 4 and an initial tone height equal to 4. The reference strand has also undergone a double bleaching treatment using L'OREAL PROFESSIONNEL BLOND STUDIO 9 powder.
[0067] Figure 12 shows the smoothing obtained after illuminating the bleached strand of Figure 6 with a wavelength of 385 nm and with an illumination power of 8 Watts per cm². The speed of movement is 1.3 cm per second and 4 passes of the strand are made in front of the illumination sources.
Claims
Demands
1. A process for shaping keratin fibers, in particular human keratin fibers, especially hair, comprising the steps of: - applying mechanical tension to the keratin fibers to be treated, - exposing said keratin fibers to light radiation having a maximum emission in a wavelength range between 280nm and 650nm, the process being characterized in that the keratin fibers to be treated receive an energy illumination greater than or equal to IW / cm2 and less than or equal to 50 W / cm2 and in that the keratin fibers to be treated are moved in front of an optical illumination window so as to be subjected to a total fluence greater than or equal to 10 J / cm2 and less than or equal to 100 J / cm2 per pass.
2. The method according to claim 1, characterized in that the keratin fibers to be treated receive an energy illumination greater than or equal to 6 W / cm2.
3. A method according to any one of claims 1 or 2, characterized in that the keratin fibers to be treated receive an energy irradiance less than or equal to 8 W / cm2.
4. A method according to any one of claims 1 to 3, characterized in that the method comprises a single step of exposure to light radiation.
5. A method according to any one of claims 1 to 3, characterized in that the method comprises a plurality of light exposure steps, the steps being repeated successively.
6. A method according to any one of claims 1 to 3, characterized in that the wavelength of maximum emission of the light radiation is greater than or equal to 315nm, better greater than or equal to 350nm, or even greater than or equal to 370nm.
7. A method according to any one of claims 1 to 6, characterized in that the wavelength of maximum emission of the light radiation is less than or equal to 500nm, or even less than or equal to 460nm.
8. A method according to any one of claims 1 to 7, characterized in that the keratin fibers to be treated are subjected to mechanical tension with a force greater than or equal to 0.1 N, preferably su- greater than or equal to IN, preferably greater than or equal to 15N.
9. A method according to any one of claims 1 to 8, characterized in that the keratin fibers to be treated are put under mechanical tension with a force less than or equal to 1000N, preferably less than or equal to 30N, better less than or equal to 20N.
10. A method according to any one of claims 1 to 9, characterized in that the keratin fibers to be treated are placed under tension in a substantially straight manner.
11. A method according to any one of claims 1 to 9, characterized in that the keratin fibers to be treated are put under tension and wound.
12. A process according to any one of the preceding claims, characterized in that the process is carried out in the absence of a composition capable of reducing disulfide bonds of the keratin fibers to be treated.
13. A process according to any one of claims 1 to 12, characterized in that the process is carried out on keratin fibers to be treated which have been previously moistened with an aqueous composition, the aqueous composition being water.
14. A process according to any one of claims 1 to 12, characterized in that the process is carried out on keratin fibers not previously moistened.
15. A method according to any one of claims 1 to 14, characterized in that it does not include a step of applying an oxidizing composition suitable for restoring disulfide bonds.