GB2585393A - Cosmetic composition - Google Patents

Abstract

A method of providing an aesthetic effect on a keratinous substrate, for example human skin, comprising applying a chromic composition to the substrate of a subject, the chromic composition comprising a colourant and optionally a pigment or dye, the colourant changing colour upon being subjected to a stimulus. Preferably, the stimulus is heat or light, e.g. the colourant is a thermochromic liquid crystal or a thermochromic- or photochromic- leuco colourant. Preferably, thermochromic colourants change colour in the range 25 °C to 37 °C. Preferably, the composition is sprayable. The composition may comprise any of water, a volatile solvent, a film-forming component and a rheology modifier (e.g. polyethylene glycol). Also claimed are compositions suitable for application to a keratinous substrate (e.g. skin) comprising a colourant comprising a liquid crystal and/or a leuco dye. Further claimed is a sprayable chromic composition comprising a chromic composition comprising a UV or heat responsive colourant dispersed in a base composition wherein the base composition comprises a film-forming component and a carrier.

Description

COSMETIC COMPOSITION

This invention relates to a cosmetic composition, particularly to a cosmetic colour-change composition for application to a keratinous substrate, for example human skin, eyelids, and lips to produce a coloured effect in response to a stimulus in the environment or from the subject. The invention relates to a cosmetic colour-change composition which provides markings in response to stimulus from the subject or in response to external stimulus for example natural or artificial light (UVA/UVB), wind, temperature, water and any other changes in ambient conditions.

A wide range of cosmetics for coating keratinous substrates such as nails, skin, lips and the like are available in the personal care market to provide aesthetic and/or functional effects. Such compositions may be solvent-based or may be aqueous-based depending on the particular type of product and typically must comply with toxicology and other safety and testing standards and protocols.

Cosmetic products such as make-up or other products for application to skin containing colour-change or chromic components such as photochromic colourants are also well known. Chromic components change between a first and second state which may both be coloured or white or one coloured or white and the other colourless, in response to a change in an external condition such as application of energy for example through a change in temperature or pressure or incidence of light. Chromic components which change colour with a change in temperature are known as thermochromic, with pressure as piezochromic, and, with light, as photochromic. Hydrochromic components typically are white when dry and become translucent when wet thereby providing a change in opacity as between the wet and dry states. Chromic components which change colour or opacity between different states or in response to a stimulus are referred to herein as "colourants".

US-A-6306409 describes a light-responding high colour-rendering make-up cosmetic preparation. US-A-6080415 describes a make-up product combining a photochromic colourant and a UV screening agent. US2012/0024308 describes a method of making up with light sensitive make-up using a photochromic composition which is in an already developed state Typically, cosmetic products containing a chromic composition are employed to mask natural skin marks or blemishes or changes in the colour of the skin, for example blushing, for aesthetic taste or for functional effects, for example providing an indication as to when sunscreen may need to be applied.

We have now devised a method of providing a visual effect on a keratinous substrate by applying a composition which changes colour in response to an external stimulus or a stimulus from the substrate whereby a visual effect appears or disappears or changes on the substrate.

In a first aspect the invention provides a method of providing an aesthetic effect on a keratinous substrate, for example human skin, comprising applying a chromic composition to the substrate of a subject, the chromic composition comprising a colourant and optionally a pigment or dye, the colourant changing colour upon being subjected to a stimulus.

Suitably, the colourant is dispersed in a carrier, so as to provide a film comprising the chromic composition on an area of the substrate.

In a second aspect, the invention provides a cosmetic chromic composition for application to a keratinous substrate comprising a colourant comprising a leuco dye and/or a liquid crystal and optionally a pigment and/or dye.

The chromic composition is applied to a keratinous substrate of a subject which is suitably selected from eyelids and area around the eyes, cheeks, temple area, lips, neck, collar bone, upper and lower limbs, torso and hands. Preferably the chromic composition is responsive to a change in temperature or light and is tailored to change colour at pre-determined temperatures or upon incidence of light of a certain wavelength range" thereby enabling colour change to occur in response to external elements providing a stimulus, for example sunlight, a gentle breeze, a warm fire, or different seasons.

Suitably, the chromic composition provides an aesthetic effect by changing between translucent and coloured, colourless to coloured or vice versa or both. The colourants in the chromic composition are selected to provide a particular desired colour effect and a colour effect of the desired intensity. The time period over which the colour change occurs is suitably tailored according to the desired effect. The colourant may provide a lower or higher visual strength. The term "visual strength" refers to an intensity of colour on a scale of 1 to 5 with 1 being the lowest and 5 the highest, as assessed by a trained colourist. Colourants with a higher visual strength provide a higher intensity of colour which is more visually impactful to the observer.

The colourant may change colour upon activation by an external stimulus such as heat or light, for example ultra violet, and undergo transition to provide a more intense colour and then fade to a less intense colour. In a preferred embodiment, the colourant is thermochromic.

The rate of transition to a colour of maximum intensity and the rate of fade from a colour at its maximum intensity to a colour of lower intensity or colourless may be tailored according to the desired effect. The rate of fade of a colourant may be measured by reference to a half-life, being the time taken for the colour to fade from its maximum intensity to half that intensity. The time taken for the colour to fade from its maximum intensity by 25, 50 and 75% may be referred to as T1/4, T1/2 and T3/4 respectively. Preferably the half life is from 1 to 600 seconds, more preferably from 2 to 500 seconds and especially from 5 to 420 seconds.

Visual strength and half life may be measured using a spectrophotometer. The maximum colour intensity may be measured at any suitable wavelength and is preferably measured at lambda max, the wavelength of maximum absorbance in the coloured state of the colour change component. The colourant sample is suitably prepared as a 0.05% by volume solution in a solvent at 23 °C in a carrier system of low density polyethylene The chromic composition may comprise one colourant or a mixture of colourants. The colourant may comprise any known compound capable of undergoing a change in colour in response to a stimulus and is preferably selected from a leuco colourant and a liquid crystal. The leuco or liquid crystal colourant preferably comprises a thermochromic leuco or liquid crystal colourant. The leuco colourant or liquid crystal may be encapsulated. Unencapsulated liquid crystal may be employed.

Suitably, the colourant comprises liquid crystal, preferably a spray dried liquid crystal, a freeze dried liquid crystal or a dispersed unencapsulated liquid crystal. The liquid crystal may be an encapsulated spray-dried liquid crystal or an encapsulated freeze-dried liquid crystal.

The colourant is suitably selected from a thermochromic liquid crystal, a thermochromic leuco dye and a photochromic leuco. In a preferred embodiment, the colourant is selected from a thermochromic leuco dye and a thermochromic liquid crystal selected from a spray dried encapsulated liquid crystal, a freeze dried encapsulated liquid crystal or a dispersed unencapsulated liquid crystal.

Suitable photochromic leuco include t-type, for example spiropyran, spirooxazine and naphthpyrans, and p-type photochromic liquid crystals for example diarylethene compounds. T-type compounds tend to fade depending on the thermal stability of the coloured for on the colourant whereas p-type photochromics tend to maintain their transition colour until activated by a particular wavelength of light. P-type photochromic compounds accordingly provide a more durable or permanent colour transition and are preferred for cosmetic products intended for longer wear.

Preferred photochromic leucos include those available from the Reversacol Vivimed TM range which provides a range of options for colour change, transition times and solubilities, and p-type photochromics such as diarylethene compounds available from Yamada In one embodiment, unencapsulated photochromic compound is preferred as it provides a colour transition from colourless to coloured with UV activation and may provide an intense or impactful colour-change to the observer. An encapsulated photochromic is slightly coloured in resting state and suitably transitions to a more vibrant colour upon UV activation. Unencapsulated liquid crystals are typically oils and are suitably dispersed in a solvent. Examples of suitable solvents include butanone oxime, high chain acetates, high chain alcohols, mineral spirits, toluene, white spirits, DMP, high chain ketones, ethyl acetate, naptha, PMA, monoethanol amine. Preferably, the solvent is cosmetically acceptable and preferred solvents include methanol, ethanol, butyl acetate, isobutanol, silicones, toluene, xylene, acetone, isopropanol, hydrocarbons and glycols. The term "cosmetically acceptable" means a material which is not toxic to the skin and meets appropriate safety and regulatory requirements for use on human skin.

The colourant may also be selected from a vapochromic colourant, which is responsive to the presence of certain gases or vapours and may be used to detect the presence of pollution or other environmental agents, and solvatochromic colourant which is responsive to changes in pH and polarity, for example changes in the pH of the substrate skin.

Known cosmetic compositions include compositions which are intended to conceal skin colours or marks or blemishes, or to play down or obscure natural changes in skin tone.

The present invention complements natural skin tone and changes and the chromic composition suitably augments the skin of the subject by providing a colour change effect and enhance aesthetic individuality rather than to conceal or diminish individuality, for example as with concealers or foundation products.

Suitably, the chromic composition changes hue to adapt to the substrate or a change in the substrate of the subject, particularly to the temperature of the skin of the subject. The chromic composition is suitably tuned to provide a pre-determined effect, for example accentuating a warm skin tone, augmenting a natural colour change of the skin due to blushing, providing a colour change effect in response to natural changes in skin tone or colour.

In a preferred embodiment, the chromic composition is a blusher or "rouge" composition, suitable for colouring the cheeks in varying shades, or the lips, typically in red. The chromic composition is suitably in the form of a cream; powder, pressed solid or pomade or gel-solid.

The chromic composition may, in another embodiment; be formulated as a "highlighter' composition which may provide emphasis to a part of the face, for example, the brow bone, area around the eyes and the cheekbones.

The chromic composition may act as an indicator of a change in environmental conditions, with colour change occurring when the subject moves to a different environment which has a different type or level of stimulus for the colourant, for example moving from inside to outside where the temperature or presence or level or incidence of UV light may be different, creating a natural blush effect, or an accentuated blushing effect when the person blushes.

The chromic composition may be tailored to change in response to the level of incident light, for example to change colour in response and to the rising sun or the sun being shaded and the like.

The chromic composition may comprise a hydrochromic colourant whereby the composition changes colour in response to the level of moisture, for example the presence or absence of rain or snow.

Whether due to a change in temperature, light or moisture or any combination thereof, in this way, the aesthetic appearance of the subject may be attuned to the environment according to the taste of the subject by including a thermochromic, photochromic and/or hydrochromic colourant in the chromic composition. Accordingly, colour-change in the chromic composition may be provided by different types of colourants including leuco-colourants, particularly thermochromic leuco-colourants which are responsive to changes in temperature, photochromic leuco colourants which are responsive to UV or other light and hydrochromic leuco colourants which are responsive to contact with water, and liquid crystals.

The type of colourant(s) and the level of the colourant in the chromic composition and the temperature, UV level or moisture level at which the colourant changes colour is selected according to the intended circumstances of use and the desired aesthetic effect.

The chromic composition may be tuned to average body temperature of the subject and so may be tuned to provide a colour-change effect in a cold climate, hot climate or temperate climate. The chromic composition may also be tuned to change colour with a local change in environment, for example a gust of wind, temporary sunlight or shade and the like.

For chromic compositions comprising a thermochromic colourant, as the colourant reaches the temperature at which it activates to change colour, a visual colour change from translucent to coloured occurs and is observable. The chromic composition may comprise a plurality of colourants to provide multiple colour changes. Preferably, the colourants are selected from red, yellow, blue, orange, purple, white and black to provide a blusher or a highlighter effect.

Where the colourant (or one of them) comprises a liquid crystal, the liquid crystal will provide an appearance of passing through all colours of the visible spectrum. As the temperature to which the chromic composition is subjected falls, the colourant suitably changes to its lower temperature state, returning to translucent. The colour-change effect may be tailored so as to be reversible or irreversible.

In a preferred embodiment, the colourant comprises a thermochromic leuco colourant and/or a liquid crystal or a combination of such colourants which provide a change in colour of the chromic composition within the range from -5°C to 60°, preferably from 0°C to 40°C and especially from 25°C to 37°C. Where more than one colourant is present, the temperature at which each colourant changes colour is suitably different to that at which any other colourant changes colour.

In one embodiment, the chromic composition comprises a first colourant which changes colour at a temperature in the range 25 to 37°C and a second colourant which changes colour at a temperature in the range 25 to 37°C. The transition temperature for the two or more colourants may be the same or different but preferably is different to the temperature at which the first colourant changes colour.

The chromic composition may be applied to the substrate in a random manner or in a pre-determined pattern as desired, preferably to provide a body of colour over an area such as the brow, cheekbones, area around the eyes, lips, hands, upper or lower limbs or as part of the torso of the subject. The chromic composition may be applied directly to the skin or on top of a coating comprising a colourant which comprises a "static" or colour change colourant, for example a blusher, applied to the skin. Alternatively, the chromic composition may be applied in combination with application of a coating comprising a colourant.

The term "static" colour refers to a leuco colourant or a liquid crystal which does not change colour under the conditions of use. Thus while the colourant is capable of colour-change, it does not typically exhibit colour change under the conditions of use and shows a fixed colour.

In one embodiment, a colourant is applied to the skin as a blusher over an area of the subject for example on a part of the face such as cheekbones and a chromic composition is applied in discrete areas on top of the coating or may be incorporated with the coating and applied in combination with it to the skin.

In addition to the chromic composition, a further colour-change composition may be applied on top of or in proximity to the chromic composition in discrete areas. The further colour-change composition is intended to provides discrete areas which, in their coloured state, differ in colour from the chromic composition or underlying skin so as to provide discrete, contrasting areas of colour which suitably appear in response to a stimulus from the subject or an external stimulus. The discrete areas of the further colour change composition may be applied to the skin in a random manner or in a pattern as desired, preferably to provide an appearance of freckles having a natural colour or an artificial colour. The discrete areas may be small and comprise multiple discrete areas and may be applied directly to the skin or on an area to which the chromic composition has previously been applied or in combination with application of the chromic composition.

The stimulus may be provided by a change in temperature, application or removal of incident light or water or a combination of two or more stimuli, for example heat and light.

Preferably, the colourant changes colour or is activated in response to one or more of heat, cold, light for example UV light and sunlight, wind and water, for example rain and snow.

In one embodiment where the chromic composition is applied to human skin, the stimulus is provided by a temperature change in the skin. For example when a subject blushes, the temperature of the skin typically changes and the chromic composition is adapted to change from a first state to a second state over a temperature change of up to 5°C, preferably from 0.5 to 2°C.

The period between which the chromic composition changes from a first state, for example transparent, to a second state, for example visible and readily apparent to the human eye, is referred to herein as the "transition time". The chromic composition may transition from a first state to a second state or to a further state over any desired time upon application of a stimulus.

In the case of a thermochromic composition the transition time may depend on the period of time over which the ambient temperature or the temperature of the composition changes from that temperature at which the first state prevails to that temperature at which the second state prevails. Suitably, the transition time is from 0.1 seconds to 10 minutes, preferably from 0.5 seconds to 5 minutes, more preferably from 0.5 seconds to 1 minute, especially 1 to 30 seconds and particularly from 1 to 10 seconds.

The desired transition time may be tailored according to aesthetic or functional requirements. For example, a slower transition time, for example from 3 to 30 seconds may be desirable. Where the chromic composition provides a functional effect, for example giving an indication of the intensity of incident UV light, a more rapid transition time may be preferred, for example from 1 to 5 seconds. The transition time may be tailored and calibrated to provide an indication of the intensity of incident UV light on a qualitative, semi-quantitative or quantitative basis.

In one preferred embodiment, the colourant comprises a thermochromic leuco colourant and/or a thermochromic liquid crystal and is activated by heat or cold relative to ambient. The liquid crystal and/or leuco colourant is suitably visible or invisible on the skin at room temperature and disappears or appears upon application of heat or cold and returns to visible or invisible at room temperature. Heat may be applied by sunlight exposure to sun, use of a hair dryer or in any other manner. Cold may be applied by any natural or artificial means, for example windchill or exposure to dry ice.

In another embodiment, the colourant comprises a UV activated photochromic compound or any chosen colour of colourant which is visible under UV light for example direct sunlight but disappears or fades as the incidence of UV light decreases or UV light is withdrawn. For example in one embodiment the colourant suitably appears dark pink in high sunlight, light pink in low levels of sunlight or in a cloudy environment and may be invisible in the absence of sunlight or when indoors.

In a further embodiment, two separate chromic compositions may be employed together, one to provide a larger area of static or fixed colourant or colour-change colourant and another applied in discrete areas within or away from the said area to provide a freckle effect with freckles appearing or disappearing in response to a stimulus. Compositions may also be blended together to create new shades and hues of colours or types of multi effects, for example the composition may comprise a blend of UV responsive photochromic red colourant with a heat responsive thermochromic blue colourant to give a tri colour effect.

The chromic composition may be formulated to provide a natural shade or colour, for example beige, brown, red and pink or to provide a shade or colour which is clearly unnatural for example vivid red and blue, as desired.

In another embodiment, the chromic composition may provide a visually discernible indicator to provide an indication of exposure to UV rays, for example as described in US-A-9545374. For example, a chromic composition may be applied to human skin before, after or in combination with the application of sunscreen and be adapted to provide a visual indication as the level of active component in the sunscreen decreases, the chromic composition changes colour thereby providing a visual indication of the reduced effectiveness of the sunscreen.

The chromic composition may be applied by any suitable means including by applying a coating to the skin manually for example using fingers or hands, by use of an implement in contact with the skin for example known make-up implements, brush, sponge, pencils and the like or may be applied as a continuous or discontinuous spray or by spattering or a brush to flick a composition onto the skin from a distance. A sprayable composition is suitably applied using a known device, for example a mechanical pump spray, an aerosol spray and an air brush.

In a preferred embodiment, the chromic composition is formulated to have a viscosity which allows the composition to be sprayed onto the skin. Suitably the chromic composition has a viscosity of 1000 to 1000000cps for it to be sprayable or in gel form. The chromic composition is suitably sprayable and provides micro droplets of 1 to 100 microns or droplets of 0.1 to 5mm, preferably 0.01 to 2mm.

In a further aspect of the invention, the desired colour(s) of the chromic composition are selected based on data obtained from thermal mapping of the skin of the subject or of a calibration scale which simulates skin colour or a colour match reference scale for example an Igora Royal shade board or colour chart, Pantone or the like. The calibration scale may be produced using a simulation zone in which stimuli, for example different temperatures, are applied to a subject to provide an artificial simulation of environmental parameters and to provide mapping of the substrate or a part thereof and its responsiveness to the applied stimulus.

In another embodiment, the temperature of the subject's skin is mapped and a pre-designed chromic composition having a known colour change temperature may then be selected which is suited to the desired effect of the subject. For example, for a cold temperature change effect, such as on exposure to wind chill, a chromic composition is suitably selected which has a colour change temperature below the temperature of the subject's skin at the location where the composition is to be applied and, may be selected having regard to the temperature at which the subject wishes the colour change to occur. For a warm temperature effect such as on exposure to bright sunlight or a fire, a chromic composition is suitably selected which has a colour change temperature above the temperature of the subject's skin at the location where the composition is to be applied and, may be selected having regard to the temperature at which the subject wishes the colour change to occur. In another embodiment, the colourant may be photochromic and the chromic composition be selected from a pre-calibrated range of photochromic compositions which provide a colour change in response to sunlight and UV light or in response to indoor light, that is absence of UV.

The invention provides in a further aspect, a method of producing a bespoke chromic composition for a subject based on data indicating the responsiveness of a substrate of the subject, for example an area of skin, comprising producing a mapping, preferably a thermal mapping, of the responsiveness of the substrate to a stimulus, selecting one or more colourants, and the level or relative quantities of the colourants to provide a predetermined colour upon response to the stimulus based on the data indicating the responsiveness of the substrate and dispersing the selected colourants in a carrier produce the said chromic composition.

The data indicating the responsiveness of the substrate may be acquired using an infra red camera. The data is suitably acquired by subjecting the substrate to stimuli to determine a thermal map of an area of the skin of the substrate. The responsiveness of the substrate may be determined in relation to applied external stimuli or in response to the skin temperature of the subject.

In another method of producing a chromic composition, the colourants and the combination and relative quantities of the colourant may be selected to match a predetermined colour match reference scale or colour chart. The invention provides a cosmetic product for example a blusher, highlighter, eye shadow, eyeliner and the like, comprising a chromic composition which comprises a plurality of colourants dispersed in a carrier wherein the colourants have been selected by reference to a colour match reference scale.

Advantageously, the subject or user may be able to specifically request a colour match product based on a colour match reference for a blusher, for example to suit their individual skin colour or tone or variations therein or to match an accessory or garment or other cosmetic product.

A wide range of combinations of colourants may be employed with each colourant in a combination having a different colour-change temperature (T0). A warm colour-change chromic composition suitably has one or more Tc in the range 28 to 35°C. A cold colour-change chromic composition suitably has one or more T, in the range 5 to 12°C.

Examples of preferred combinations of colourants include: a yellow leuco colourant with T, 25 to 37, preferably 25 to 30°C and a red leuco colourant with T, 25 to 37, preferably 30 to 35°C in a weight ratio 0.1 to 50:1, preferably 0.5 to 35:1, especially 1 to 35:1 providing a colour from yellow to orange, orange/pink, pink, orange/red, bright red, pink/red, pink/orange/red with an increasing proportion of red colourant;; and a red leuco colourant with T, 25 to 37, preferably 30 to 35°C and a blue leuco colourant with T, 25 to 37, preferably 28 to 33°C and in a weight ratio 0.1 to 50:1, preferably 0.5 to 35:1, especially 1 to 35:1 providing a colour mid red to dark red, to red/purple, purple and dark purple with an increasing proportion of blue colourant.

Where the colourant is encapsulated, the encapsulation suitably comprises a known encapsulation material which is compatible with the colourant and which is approved for use in cosmetics. In one embodiment, a leuco-colourant is encapsulated in a cosmetically acceptable encapsulate. Melamine formaldehyde encapsulates are known for leuco colourants but presently are generally not approved for cosmetic use. Where such encapsulates are treated or modified and approved for cosmetic use, the leuco colourant may be encapsulated by any such treated or modified melamine formaldehyde encapsulates or known encapsulates which, in due course may be approved for cosmetic use. A liquid crystal colourant is suitably encapsulated in a gelatin and gum arabic mixture and is approved for cosmetic use. The wall material preferably comprises from 1 to 30%, more preferably 5 to 25%, for example 8% or 20% by weight of wall material based on the weight of the encapsulated chromic compound.

Suitable colourants may provide a constant or fixed colour, referred to herein as a "static" colour. The static colourant may comprise a leuco colourant or a liquid crystal.

Suitable liquid crystals include cholesteric liquid crystals which are typically based on or comprise cholesterol or other sterol derived compounds including cholesteryl carbonate esters. Other suitable liquid crystals include non-sterol based compounds, for example phenyl benzoate esters.

The liquid crystal may be selected and tailored to provide a static colour effect whereby the bulk colour does not change but there may be slight colour shifts or iridescence depending on temperature fluctuations. Alternatively, the encapsulated liquid crystal may be selected to change in state thereby providing a colour-change effect in the temperature range of intended use.

The liquid crystal may provide a single static colour or provide a colour change, for example a thermochromic colour-change between red, green and blue, in response to a change in external stimulus such as a change in temperature or incidence of UV or other light, or a combination of both static colour and colour change. The composition may be tailored to provide a desired visual appearance for particular circumstances or moods and adapted to provide a faster or slower colour-change with single or multiple colour-change within a bandwidth of temperatures or other external parameters.

The encapsulated liquid crystal is suitably tuned to provide no colour-change or change of state under conditions of its intended use thereby providing a static colour effect.

Suitable encapsulated liquid crystals are available from a range of sources including LCR Hallcrest. Non-cholesterol based liquid crystals such as phenyl benzoate esters provide bright, strong colour effects with high reflectance, suitable for premium products.

Cholesteric-type liquid crystals typically provide colour effects which are less intense than non-cholesteric liquid crystals but are of lower cost and may be suited to larger volume markets. A mixture of non-cholesteric and cholesteric liquid crystals may be employed to optimise product performance and cost. In a preferred embodiment, the liquid crystal suitably comprises only non-cholesteric liquid crystals.

The encapsulated liquid crystal is suitably incorporated into the chromic composition as an aqueous slurry comprising from 10 to 90%, preferably 15 to 80% and especially 20 to 70% of the encapsulated liquid crystal in water, for example a 40% or 50% slurry of the encapsulated liquid crystal in water.

The liquid crystal may be unencapsulated, for example a polymer disperse liquid crystal (PDLC). The chromic composition may comprise an unencapsulated liquid crystal dispersed in a carrier.

Where the colourant comprises a leuco colourant, the colour-change effect and the conditions under which it occurs, for example a particular temperature range may be controlled by modifying the colourant composition in a manner known to those skilled in that field.

The chromic composition suitably comprises a plurality of chromic compounds, preferably photochromic and/or thermochromic compounds to provide a colour which appears natural to the observer. The composition may comprise, 2, 3 or 4 or more photochromic compounds, selected to provide, in combination a natural colour.

An iridescent component may be present as an optional component of the chromic composition. Any suitable iridescent component or pigment may be employed and is preferably selected from mica and nacre. The presence of an iridescent component suitably imparts or enhances an iridescent or pearlescent effect to provide a shimmering or glittering colour effect. Suitably, the iridescent component has a particle size from 1 to 200 microns. A particle of iridescent component being of a size at the lower end of this range desirably provides a "shimmering" effect, whereas a particle size towards the higher end of the range enables individual particles to be more readily observed and provides a "glitter" effect. In one embodiment, a combination of iridescent components are employed. Preferably the iridescent component comprises a first iridescent component having a particle size towards the lower end of the range, preferably 1 to 50 microns, and a second iridescent component having a particle size to the upper end of this range, for example 50 to 200 microns.

Examples of suitable micas include micas available from Sensient Cosmetic Technologies under the trade name Covapearl® including Covapearl®, Covapearl® Star and Covapearl® Mini Star range, micas available from BASF available under the trade names ReflecksTM MultiDimensionsTM and MultireflectionsTM, Timica® particularlyu the interference range particle size range having a particle size of 9 to 37 pm, ChioneTM" Chroma-Lite®, Duochrome®, Gemtone® , Cloisonne® and Flamenco®.

The chromic composition suitably comprises the colourant and a base composition which is formulated according to the desired form of composition. The chromic composition may be in any suitable form for application to skin and is selected according to the intended use and manner of application. Examples of intended uses and suitable product types include a foundation composition, a highlighter composition, a body paint composition, a lipstick, a blusher, an eyeshadow, a mascara, an eyeliner, a make-up pencil, an eyebrow colourant, a contouring colourant, a concealer, a colour corrector and a finishing powder.

The chromic composition may be in any suitable form including a spray, a cream, a gel, a powder, a paste, a wax, an emulsion, an oil, balm, a serum, a pencil, a pen and a liquid.

The composition may be applied by hand, using an implement, for example a brush and sponge, or in any other conventional manner. In an especially preferred embodiment, the chromic composition is a sprayable composition.

The term "gel" as employed herein refers to a solid, colloid having a disperse phase and a continuous phase which combine to produce a viscous jelly-like material exhibiting no or minimal flow. The disperse phase suitably comprises the colourant, for example liquid crystal and leuco colourant, and the continuous phase comprises a polymer matrix with islands or regions of the dispersed colourant.

On application of the chromic composition to the skin of the subject, suitably the composition adheres to the skin adequately and is durable. We have found that including a film-forming component in the composition provides for improved adherence to the skin and aids spreading of the colourant to provide a desired aesthetic or functional pattern.

Accordingly, in a further aspect, the invention provides a method of providing an aesthetic effect on a keratinous substrate, for example human skin, comprising applying a chromic composition to the substrate of a subject, the chromic composition comprising a colourant dispersed in a base composition wherein the base composition comprises a film-forming component and a carrier, so as to provide a film comprising the colourant on an area of the substrate, the colourant changing colour upon being subjected to a stimulus.

Preferably, the film on the area of substrate provides a blusher or highlighter effect in response to a stimulus, for example heat.

The base composition preferably comprises a film-forming component and a carrier. The film-forming component preferably comprises a polymer suitable for forming a film on and adhering to skin. The carrier may be aqueous or oil-based, depending on the desired form of product. Where the composition is a sprayable composition, it suitably comprises water as a carrier or water and a volatile solvent, for example ethanol.

The base composition comprises a film-forming polymer. Examples of suitable film-forming polymers include polyvinyl pyrollidone/vinyl acetate polymers, for example 30/70 E and 60/40 W NP and an acrylic copolymer, for example DERMOCRYL C and DERMOCRYL E, available from AkzoNobel, DYNAMX H2O, available from AkzoNobel, EPITEX 66 polymer, the FIXATE range of polymers available from Lubrizol including FIXATE G-100 PR, FIXATE plus polymer, FIXATE superhold, FIXATE freestyle, GIOVAREZ BTB-50, COVACRYL range of polymers available from Sensient including COVACRYL P12, COVACRYL E14 WP, COVACRYL A15 WP, LUVISKOL range of polymers available from BASF including LUVISKOL VA 64, LUVISKOL VA 37-E, LUVISKOL 60/40/, WorleeMicromer range of water dispersible polymers and AVALURE UR 450 polymer available from Lubrizol.

A film-forming effect may be provided by a cross-linked polyelectrolyte or a hydrophobically modified alkali swellable emulsion thickening product. Cross-linked polyelectrolytes are preferred. Suitable cross-linked polyelectrolytes comprise a dissociating group in at least some, and desirably all of the monomeric units of the polymer, capable of dissociating in a polar and especially aqueous environment. Preferably the monomeric units comprise a group selected from -COOK -SO3H, P031-I2 and -N Ha The cross-linked polyelectrolyte may comprise a natural thickener and/or preferably a synthetic thickener. Examples of natural thickening agents include carboxymethyl cellulose, alginate, chitosan, pectin. Examples of suitable synthetic polyelectrolytes include polymers and copolymers comprising polyacrylic acid, polymethacrylic acid, polystyrene sulfonate and derivatives of these polymers and their salts. Examples of natural and synthetic polyelectrolytes are disclosed in "A comprehensive review on polyelectrolyte complexes", Meka et al, Drug Discovery Today, Vol 22, No 11, November 2017.

Reference herein to acrylic or acrylate includes methacrylic and methacrylate mutatis mutandis unless otherwise stated.

Suitably, the cross-linked polyelectrolyte comprises a polymer which has been modified so as to comprise a hydrophilic region and a hydrophobic region. Preferably, the cross-linked polyelectrolyte comprises a polyacrylate polymer, cross-polymers and copolymers of (poly)acrylates and polyacrylic acids, for example polyacrylate crosspolymer-6-2-methyl propan-2-ol, alkyl acrylates, urethane acrylates, hydrophilically modified starch, for example hydroxypropyl starch modified with a 000H, --P031-12 and ---NH2 group, polyvinyl pyrollidoneIvinyl acetate copolymers, polyquaternium compounds.

Other suitable components for the base composition in sprayable form include an alcohol, preferably short chain alcohol, for example ethanol, n-propanol, isopropanol and butanol a glycol, panthenol, for example D-panthenol and sugar alcohols. The glycol is suitably selected from one or more of glycerol, polyethylene glycol, polypropylene glycol, polybutylene glycol and a 02 to at alkylene glycol, for example PEG 32, PEG-8 and propylene glycol. The alcohol is suitably present at a level of 0.1 to 20%, preferably 1 to 10% by weight of the chromic composition.

The chromic composition may also comprise a rheology modifier. Rheology modifiers may aid dispersability and spreading. Rheology modifiers known for use in personal care products and which are soluble or dispersible in aqueous solution may be employed in the binder composition. The rheology modifier may comprise a natural thickener, a synthetic thickener and/or a dispersant or surfactant. Any known thickeners or surfactants suitable for use in the intended field of use of the composition may be employed.

Examples of natural thickeners include egg yolk, starch, cellulose, for example hydroxyethylcellulose, alginate, chitosan, agar, arrowroot, carrageenan, collagen, gelatin, guar gum, pectin and xantham gum. Examples of synthetic thickeners include alkali-swellable emulsions (ASEs), hydrophobically modified alkali-swellable emulsions (HASEs) and hydrophobically ethoxylated urethane resins (H EURs).

In one embodiment, the rheology modifier comprises a glycol, preferably selected from polyethylene glycol, polypropylene glycol, polybutylene glycol and a C2 to C4 alkylene glycol, for example PEG 32 and propylene glycol.

Examples of preferred rheology modifiers include SEPIMAX ZEN available from Seppic, VOLAREST range of materials available from Croda, ACULYN range of polymers available from Dow Chemical, for example ACULYN 28 and ACULYN 33, DHROMAPOL 5 polymer, STRUCTURE 2001, the CARBOPOL range of polymers, for example CARBOPOL® Ultrez 30 and CARBOPOL O Ultrez 21 and AMAZE XT.

In a sprayable composition, the rheology modifier may be present at a level of less than 2%, especially 0.001 to 1% by weight of the chromic composition. In a gel, the rheology modifier may be present at a level of at least 1.5%, preferably 1.5 to 5% and especially 1.5 to 3% by weight of the chromic composition.

The chromic composition may include a moisturiser and/or humectant. Examples of suitable components include D-Panthenol, glycerol, propylene glycol, polyethylene glycol, for example PEG-8 and PEG-14, FUCOGEL and Glycofilm 1.5P.

In a preferred embodiment the chromic composition is a sprayable composition and comprises a colourant and a base composition which comprises a film-forming polymer and a rheology modifier and a carrier. The carrier may comprise water or may comprise a volatile solvent and water. Optionally, other components may be included for example a humectant or conditioning agent. The colourant is suitably present at a level of 2 to 80%, preferably 2 to 50%, more preferably 2 to 40%. The film-forming polymer is suitably present at a level of 1 to 15%, preferably 2 to 10%. The rheology modifier is suitably present at a level of 1 to 7%, preferably 2 to 5%. The humectant or conditioning agent is suitably present at a level of 0.1 to 3%, preferably 0.5 to 2%. The volatile solvent is suitably present at a level of 30 to 70%, preferably 40 to 60% and water is suitably present at a level of 20 to 50% and preferably 25 to 40%.

In a preferred sprayable chromic composition, the film-forming polymer is selected from an acrylate copolymer and a silicon-containing material, for example cyclopentasiloxane and trimethyl siloxysilicate or a mixture thereof, the a rheology modifier is preferably an acrylate/beheneth-25 methacrylate copolymer, the humectant or conditioning agent or preferably a glycol, for example propylene glycol and the volatile solvent preferably comprises ethanol.

The chromic composition may be in the form of an aqueous composition and applied to the skin by any suitable means, for example, manually, using an applicator or cosmetic application tool such as a brush. The aqueous composition suitably comprises a colourant, for example a liquid crystal and a leuco colourant at a level of 2 to 40%, a film-forming agent at a level of 1 to 10% preferably 2 to 7%, a humectant, for example propylene glycol, at a level of 1 to 5, preferably 1.5 to 3% and a stabilising polymer or rheology modifier for example ACULYN 28 at a level of 1 to 4%, and optionally one or more of a chelating agent at a level of 0.05 to 2%, a preservative at a level of 0.1 to 1%, a pH adjuster at a level of 0.1 to 1% and a stabilising agent, for example glycerine at a level of 1 to 4% by weight of the chromic composition. As desired, the aqueous composition may be concentrated by removal of water or diluted by addition of water to change the viscosity to adapt the composition for the preferred method of application.

Where the composition is in the form of a wax or balm, the chromic composition is suitably a fatty organic composition and suitably comprises at least one fatty component and other components known for use in wax-based cosmetic compositions. Suitable fatty components include waxes, oils, for example castor oil, and butters, for example avocado butter. Suitable waxes include paraffinic waxes for example camauba wax, candellila wax, lanolin and beeswax. Other suitable components for the base composition include an alcohol, preferably a C5 to 040 linear and/or branched chain alcohol for example ceteryl alcohol and octyldodecanol. In a wax-based chromic composition, the colourant is suitably present at a level of 5 to 40 % and preferably 10 to 30%. Other components known to improve skin feel or sensory properties, for example myristate esters such as isopropyl myristate may be employed.

The chromic composition may have the consistency of a liquid eyeliner. The base composition suitably comprises an alcohol, preferably a glycol, a film-forming polymer, for example AVALURE UR 450, a theology modifier, for example ACULYN 28, a skin conditioning agent, for example GLYCOFILM and optionally a chelating agent. The glycol is suitably selected from one or more of glycerol, polyethylene glycol, polypropylene glycol, polybutylene glycol and a 02 to 04 alkylene glycol, for example PEG 32, PEG-8 and preferably propylene glycol. The alcohol is suitably present at a level of 0.1 to 20%, preferably 1 to 10% by weight of the chromic composition.

The chromic composition may be non-iridescent or iridescent according to the desired effect. Other appearances may be provided, for example pearlescent, gloss and fluorescent, particularly with incident light near the UV spectrum. Iridescence suitably provides scattering of incident light to provide a shimmering effect of multiple colours or a rainbow of colours and arises due to the nail product having suitable refractive characteristics. Advantageously, PDLC liquid crystals may provide iridescent qualities as well as colour-change properties.

Examples of suitable dispersants or surfactants include polysorbate 20/80, glyceryl cocoate, capryl/yl glucoside, PEG-12 dimethicone; trade name: Xiameter OFX -0193 (Dow Corning), Cetearyl alcohol and Ceteareth -20. The dispersant or surfactant may also provide a foaming function where desired, for example in the formulation of a mousse.

The chromic composition may also comprise a preservative such as a natural or synthetic antimicrobial. Examples of natural antimicrobials include, carylyl glycol, tea tree oil, potassium sorbate and sorbic acid. Examples of synthetic antimicrobials include phenoxyethanol, benzylalcohol, diazolidinyl urea, sodium benzoate, potassium sorbate, methylparaben, propylparaben and gluconolactone.

The chromic composition may comprise a UV additive. Suitable UV additives include benzophenone-4 and phenylbenzimidazole sulfonic acid (Eusolex 232 available from Merck).

The chromic composition may also comprise a perfume, especially if the composition is intended for use on the human or animal body. Examples of suitable perfumes include peppermint oil, sweet orange essential oil, menthol, linalool, parfum, methyl butyrate, citral, myrcene, limonene and eucalyptol.

The chromic composition may further comprise a further colourant, preferably a dye or pigment of fixed colour of any desired colour or combinations of colours to provide a desired aesthetic or functional effect.

In a preferred embodiment, the chromic composition comprises a cosmetically acceptable liquid crystal in combination with a cosmetic dye or pigment. In an especially preferred embodiment, the liquid crystal comprises a spray dried powder or spray dried liquid crystal, a liquid slurry liquid crystal or an unencapsulated liquid crystal dispersed in a solvent.

Where the chromic composition is intended to provide a colour which is natural in appearance, the chromic composition suitably comprises a brown colourant, for example a 0.5% aqueous solution of a brown colourant Examples of a preferred brown colourant include BASIC BROWN 17 and ARIANOR SIENNA BROWN306011 available from Sensient.

Any colourants, dyes or pigments suitable for use cosmetic products may be employed including the following used in combination or on their own; N,N -Bis(2-Hydroxyethyl)-2-Nitro-p-Phenylenediamine, 4-Amino-3-Nitrophenol, 4-Hydroxypropylamino-3-Nitrophenol, Hydroxyethyl-2-nitro-p-toluidine, HC Blue No. 12, 3-Nitro-p-Hydroxyethylaminophenol, 2-Amino-6-Chloro-4-Nitrophenol, Acid Red 33, HC Yellow No. 2, HC ORANGE NO. 1, HC YELLOW NO. 13, Basic Yellow 57, HC Red No. 3, Basic Red 76, Basic Red 51, Acid Red 92, Basic Yellow 87, Basic Orange 31, BASIC VIOLET 2, HC Blue No. 16, Acid Violet 43, Basic Brown 17 and colourants provided by Sensient® Cosmetic technologies; Arianor Jade Blue (HC Blue 15), Covalumine fire red AS (CI 15850, Alumina, Triethoxycaprylylsilane), Noir W 699 (CI 20470, Sodium Sulfate), Covalumine astral blue (01 42090, Alumina, Triethoxycaprylylsilane), Unipure white LC986 FSP (CI 77891, Perfluorooctyl Triethoxysilane, Polyperfluoromethylisopropyl Ether), Unipure red LC3071 (01 15850, Aluminum Hydroxide), Unipure white LC987 GCA (CI 77891, Sodium Cocoyl Glutamate, Cystine, Lauroyl Arginine), Covarine white WN9787 (CI 77891, Aqua, Glycerin, Xanthan Gum, Sodium Citrate), Covapate Uniwhite LC 9781 (Ricinus Communis (Castor) Seed Oil, CI 77891,Polyhydroxystearic Acid), Unipure white LC981 SGP (CI 77891, Sodium Glycerophosphate), Vert covasol W7035 (01 19140, CI 42090), unipure yellow LC182 ADT-C (CI 77492,Isopropyl Titanium Triisostearate, Bis-PEG-15 Dimethicone/IPDI Copolymer, PEG-2 Soyamine), unipure black LC989 ADT-C (CI 77499,Isopropyl Titanium Triisostearate, Bis-PEG-15 Dimethicone/IPDI Copolymer, PEG-2 Soyamine), unipure black LC988 FSP (CI 77499, Perfluorooctyl Triethoxysilane, Polyperfluoromethylisopropyl Ether), phat black DC 9206 (mixture of CI61565, CI60725, basic brown 16, acid violet 43, basic red 76, CI 26100), Arianor flash deep black (Basic Blue 99,Basic Brown 16, Acid Violet 43, Basic Red 76, Basic Yellow 57, Basic Brown 17, Polyquaternium-37, Hydrolyzed Yeast Protein) The chromic composition of the invention may be combined with or incorporated in a known eye-shadow composition or blusher composition to provide a novel blusher or eye-shadow product.

In a further aspect, the invention provides a cosmetic product comprising i) a known or conventional blusher composition or a known or conventional eye-shadow composition and ii) a chromic composition according to the invention.

Preferably the chromic composition comprises a liquid crystal, especially a spray-dried or freeze dried liquid crystal. Suitably, the spray-dried or freeze dried liquid crystal is in powder form.

Unless otherwise specified, all percentages are based on percentage by weight of the chromic composition.

The invention is illustrated by the following non-limiting examples.

Example 1 (Leuco gel) A composition was prepared by mixing together the components as shown in Table 1 to produce a water-based composition for application to skin to provide a blusher effect.

Table 1

Phase Raw material Usage Level (%) A Water 32 Propylene glycol 8 (conditioning effect) Carbopol (thickener) 0.3 Leuco thermochromic 8 colourant Dermacryl C (film former) 20 B AMP 1 C Water 30 D Germaben (preservative) 0.4 This composition was applied to the face of a subject around the eye area, brow and cheekbones. The results are shown in Figure 1 in black and white and Figure 8 in colour. With the composition at a lower temperature, the composition was dormant and essentially invisible such that the underlying colour of the skin was observed as shown in Figure 1 in black and white and Figure 8 in colour. At a higher temperature, the composition changed colour and became active as shown in Figure 1 in black and white and Figure 8 in colour Example 2 (Highlighter Emulsion) A composition was prepared by mixing together the components as shown in Table 2 to form a water -based composition for application to skin.

Table 2

Phase Raw material Usage Level (%) A PEG-32 48 PEG-8 15 B PLURONIC 123 12 C Unencapsulated LC 25

Example 3

A composition was prepared by mixing together the components as shown in Table 3 to form a water -based sprayable composition for application to skin to provide a blusher effect.

Table 3

Phase Raw material Usaqe Level (%) A Thermochromic leuco 65 colourant Water 35 0.5% basic brown solution 0.3 A number of compositions were prepared with different the thermochromic leuco colourants being comprised of a combination of colourants as set out below - a yellow leuco colourant with To 25 to 30°C and a red leuco colourant with To to 35°C in a weight ratio of from 1 to 35:1 providing colours from yellow to orange, orange/pink, pink, orange/red, bright red, pink/red, pink/orange/red with an increasing proportion of red colourant; and -a red leuco colourant with To 30 to 35°C and a blue leuco colourant with T, 28 to 33°C in a weight ratio 0.1 to 50:1, preferably 0.5 to 35:1, especially 1 to 35:1 providing a colour from mid red to dark red, to red/purple, purple and dark purple with an increasing proportion of blue colourant

Example 4

The chromic composition of Example 1 was applied to the face of a subject around the cheek bones, brow and eyes and subjected to an increase in temperature. The chromic composition changed colour progressively over 3 seconds and the transition is shown in the photographs shown both in black and white in Figures 2 to 7 and in colour in Figures 9 to 14.

Example 5

A composition was prepared by mixing together the components as shown in Table 4 to produce a spray dried liquid crystal in a powder formulation for application to skin to provide a blusher, highlighting, contouring or eyeshadow effect.

The spray dried liquid crystal 3105W was prepared by diluting a commercially available encapsulated liquid crystal slurry to a water content of 30 to 33%. The slurry was subjected to a spray drying process in which 1 litre of liquid crystal slurry was fed to the spray-drying vessel operating with at an inlet temperature of 152 to 156°C and an outlet temperature of 72-70°C with an initial pump speed of 6 rpm and a main speed of 14 rpm. A yield of 82% of spray dried encapsulated liquid crystal was obtained.

Table 4

Phase Raw material Usage Level (%) Mass (g) Talc (bulking A agent/filler) 40% 8 Zinc Stearate (bonding agent) 3% 0.6 Boron Nitride (bulking 5% 1 agent, anti-caking) B Mica (filler) 10% 2 Red Iron Oxide (pigment) 0.8% 0.16 Black Iron Oxide (pigment) 0.4% 0.08 Yellow Iron Oxide: CI 77 492 (pigment) 1% 0.2 Red 30 Lake/CI 73360 (pigment) 0.8% 0.16 C Sodium 0.3% 0.06 Benzoate (preservative) 4% 0.8 Cromollient DP3A (spreading agent) D Spray Dried LC: 3105W (colourant) 34.7% 6.94 E Perfume Spice Blush (optional) 100.00% 20 The components of phase A were mixed together, the components of phase B were mixed together, the phase B mix was worked into the phase A mix with moderate agitation until homogeneous. The phase C components were mixed together and then added to the homogeneous mix. Phase D and optionally phase E was then mixed into the homogeneous mixture to provide the chromic composition.

Any of the pigment components listed in phase B may be any combination of pigments with a total pigment content from 0.5 to 3%. Examples of suitable pigments include acid red 33, acid blue 9, acid green 25, acid violet 43, acid orange 7, acid red 33, acid red 52.

The composition of Table 4 provided a reddish brown colour.

Cromollient DP3A-(Di-PPG-3 Myristyl Ether Adipate is a di-ester of propoxylated myristyl alcohol and adipic acid which is a slow spreading oil which adheres to skin, allowing active ingredients to be retained more effectively and adhered to the skin for long lasting effect.

Example 6

A composition was prepared with an aqueous-based dye solution (phase B) by mixing together the components as shown in Table 5 to produce a spray dried liquid crystal in a powder formulation for application to skin to provide a blusher effect. The spray dried liquid crystal was produced in the manner described in Example 5 and the phases produced and combined in the same manner as in Example 5.

Table 5

Phase Raw material IDH number / R number (if applicable) Usage Level (%) Mass (g) Bulking Talc agent/filler - 40.00% 8.00 A-Bulk of formula blush to create powder Binding agent Bulking agent/ anti- 3.00% 0.60 Zinc Stearate Boron Nitride caking/ mattifying 5.00% 1.00 agent -Mica (white) Filler 10% 2.00 B-aqueous dye Aqueous dye solution solution, e.g. Acid Red 33 2.4% (1% solution) C Sodium Benzoate Preservative 0.30% 0.06 Cromollient DP3A 4.00% 0.800 *Optional* Spreading agent D-chromic colour Spray Dried Liquid Active colourant, component crystal chromic composition 34.70% 6.94 100.00% 20 The aqueous dye solution in Phase B may comprise be any combination of aqueous dye dispersions, suitably between 0.5-and 3% overall concentration in the composition: The dye in this composition creates a pink colour with the chromic component turning red, pink and then purple on application of heat A further composition was produced by replacing the aqueous dye in Table 5 with an aqueous solution of acid blue 9 pigment at the same level. The composition was applied to black card by hand to mimic application to the skin. A finger was placed under the black card to impart body heat to the composition which caused activation of the colourant providing a colour change effect as shown in Figures 15 and 16. The composition also readily adhered to the surface.

Claims (29)

1. CLAIMS1. A method of providing an aesthetic effect on a keratinous substrate, for example human skin, comprising applying a chromic composition to the substrate of a subject, the chromic composition comprising a colourant and optionally a pigment or dye, the colourant changing colour upon being subjected to a stimulus.
2. 2. A method according to claim 1 wherein the colourant is dispersed in a carrier, so as to provide a film comprising the chromic composition on an area of the substrate.
3. 3. A method according to any one of claims 1 or 2 wherein the chromic composition is adapted to change between a translucent and coloured appearance in response to the stimulus.
4. 4. A method according to any one of the preceding claims wherein the keratinous substrate is selected from eyelids and area around the eyes, cheeks, temple area, lips, neck, collar bone, upper and lower limbs, torso and body.
5. 5. A method according to any one of the preceding claims wherein the chromic composition comprises a pigment or dye selected from red, yellow, blue, orange, purple, white and black to provide a blusher or a highlighter effect in combination with the colourant.
6. 6. A method according to any one of the preceding claims wherein the colourant comprises one or more of a thermochromic leuco colourant and/or a thermochromic liquid crystal.
7. 7. A method according to claim 6 wherein the thermochromic leuco colourant and/or thermochromic liquid crystal provides a change in colour of the chromic composition within the range from -5°C to 60°.
8. 8. A method according to claim 6 wherein the colourant provides a change in colour of the chromic composition in the temperature range from 25°C to 37°C
9. 9. A method according to any one of the preceding claims wherein the colourant comprises a thermochromic liquid crystal, preferably a spray dried liquid crystal, a freeze dried liquid crystal or a dispersed unencapsulated liquid crystal.
10. 10. A method according to claim 9 wherein the spray-dried liquid crystal or freeze-dried liquid crystal is encapsulated. 5
11. 11. A method of producing a bespoke chromic composition for a subject based on data indicating the responsiveness of a substrate of the subject comprising producing a mapping of the responsiveness of the substrate to a stimulus, selecting one or more colourants and the level or relative quantities of the colourants to provide a pre-determined colour upon response to the stimulus based on the data indicating the responsiveness of the substrate, and dispersing the selected colourants in a carrier to produce the said chromic composition.
12. 12. A method according to claim 11 wherein the colourants and the combination and relative quantities of the colourant are selected to match a pre-determined colour match reference scale.
13. 13. A method according to any one of the preceding claims wherein the chromic composition is sprayable.
14. 14. A method according to any one of the preceding wherein the colourant is dispersed in a base composition wherein the base composition comprises a film-forming component and a carrier.
15. 15. A method according to claim 14 wherein the film-forming polymer is selected from polyvinyl pyrollidone/vinyl acetate polymers, an acrylic copolymer, cyclopentasiloxane, trimethylsiloxysilicate, silicone acrylate, a cross-linked polyelectrolyte, a polyacrylate polymer, cross-polymers and copolymers of (poly)acrylates and polyacrylic acids, urethane acrylates and hydrophilically modified starch.
16. 16. A method according to claim 15 wherein the carrier comprises water and optionally a volatile solvent
17. 17. A method according to any one of the preceding claims wherein the chromic composition comprises a rheology modifier.
18. 18. A method according to claim 17 wherein the rheology modifier is selected from polyethylene glycol, polypropylene glycol, polybutylene glycol and a C2 to C4 alkylene glycol.
19. 19. A method according to any one of the preceding claims wherein the chromic composition comprises i) a thermochromic colourant and/or ii) a pigment or dye.
20. 20. A cosmetic chromic composition for application to a keratinous substrate, preferably skin or lips, comprising a colourant comprising a liquid crystal and/or a leuco dye and optionally a pigment or dye.
21. 21. A cosmetic chromic composition according to claim 20 wherein the colourant is selected from a thermochromic liquid crystal, a photochromic leuco and a thermochromic leuco dye.
22. 22. A cosmetic chromic composition according to claim 20 or 21 wherein the colourant is selected from a thermochromic leuco dye and a thermochromic liquid crystal.
23. 23. A cosmetic chromic composition according to claim 22 wherein the thermochromic liquid crystal is selected from a spray dried encapsulated liquid crystal, a freeze dried encapsulated liquid crystal or a dispersed unencapsulated liquid crystal.
24. 24. A cosmetic chromic composition according to any one of claims 20 to 23 comprising photochromic leuco dye selected from solar yellow, rush yellow, sunflower, corn yellow, flame, ruby, berry red, poppy, cardinal, cherry, lilac, claret, plum red, amethyst, royal purple, oxford blue, velvet blue, storm purple, palatinate purple, aqua green, sea green, mulberry, amber, volcanic grey, heather, misty grey, midnight grey, graphite and brown.
25. 25. A cosmetic chromic composition according to any one of claims 20 to 24 in the form of a powder, compressed solid, solid gel or pomade,
26. 26. A method of creating a visual appearance of natural features, on human skin comprising forming fine droplets of a chromic composition responsive to UV radiation or changes in temperature, the chromic composition comprising a colourant dispersed in a base composition wherein the base composition comprises a film-forming component and a carrier, and applying the formed droplets to the skin of a subject so as to form a continuous area of the colourant on the skin to provide a blusher or highlighter effect.
27. 27. A sprayable chromic composition comprising a chromic composition comprising a UV or heat responsive colourant dispersed in a base composition wherein the base composition comprises a film-forming component and a carrier, the chromic composition being capable of application to skin of a subject by spraying so as to form a continuous areas of the colourant on the skin.
28. 28. A cosmetic product comprising a chromic composition according to any one of claims 20 to 25 comprising i) a blusher composition or an eye-shadow composition and fi) a chromic composition according to any one of claims 20 to 25.
29. 29. A cosmetic product comprising a chromic composition which comprises a plurality of colourants dispersed in a carrier wherein the colourants have been selected by reference to a colour on a colour match reference scale.