EP2480498A1

EP2480498A1 - A particulate fluorescer and a process for preparing the same

Info

Publication number: EP2480498A1
Application number: EP10747459.5A
Authority: EP
Inventors: Suresh Sambamurthy Jayaraman; Sudipta Ghosh Dastidar; Anandh Panchanathan; Ramasubramaniam Rajagopal; Bharath Palanisamy
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2009-09-24
Filing date: 2010-08-30
Publication date: 2012-08-01
Also published as: EA201200529A1; BR112012005667A2; WO2011036029A1; CN102822095A; MX2012003568A; ZA201201517B

Abstract

This invention relates to a particulate fluorescer and a process for preparing the same. More particularly the present invention relates to a bipolar particulate fluorescer for use in laundry detergent composition, fabric conditioner and cosmetic compositions and a process for making the same. In view of the foregoing, it is an object of the present invention to provide a fluorescer with improved retention to the fabric so that larger amounts of fluorescer will be available even after rinsing. It is yet a further object of the invention to provide a fluorescer with improved stability when formulated in cosmetic compositions. Surprisingly it has been found that fluorescer molecules tagged by surface reaction on to naturally occurring asymmetric clay surfaces, act as a fluorescer particle with improved retention properties, low fabric specificity, higher stability in cosmetic formulations and/or yielding improved brightness to substrate (skin/fabric) on use and meets at least one of the above mentioned objects.

Description

A PARTICULATE FLUORESCER AND A PROCESS FOR PREPARING THE SAME

Field of the Invention

This invention relates to a bipolar particulate fluorescer for use in laundry detergent compositions, fabric conditioners and personal care compositions and a process for making the same. Background of the invention

Optical enhancers/brighteners are used widely in many

technological fields like detergents and personal care, especially in laundry (wash and fabric conditioning) and in personal care compositions (e.g. skin lightening and sunscreen compositions) for giving a consumer desired optical effect to the substrates.

Modern day consumers prefer a detergent product that looks white. Consumers also prefer that fabric articles, washed with a detergent product, look bright. Similarly there is a desire of consumers in many parts of the world to change the

appearance of their skin, either by skin tanning or by skin brightening .

To accommodate those consumer preferences, it is a common practice to add fluorescer molecules in detergent compositions to make a detergent powder look white and attractive in appearance and to provide a brightening benefit to fabric articles washed with this powder.

Fluorescers are also known as optical brighteners . These molecules generally absorb amongst other invisible light such as ultraviolet light, and emit this energy in another form. For the purpose of detergent products, the light is generally emitted in the visible spectrum, preferably blue or green light. The extra emission in the blue and/or green range of the spectrum makes fabrics or textiles washed with detergent comprising fluorescer molecules look brighter after washing. Fluorescer molecules get adsorbed in or otherwise attached to the fabric and give the desired effect.

There are many detergent powders available in the market comprising various fluorescer molecules.

The drawback of the currently available fluorescer molecules is that high amounts of fluorescer get lost during the rinsing stages of fabric washing processes. Therefore washed fabrics end up with a very low amount of adsorbed fluorescer which is not sufficient to produce the desired effect. Therefore the dosage of fluorescer in washing products has to be higher than required to compensate for the loss. Since fluorescers are relatively expensive ingredients it is desired to reduce the loss on rinsing.

Another problem of known fluorescers is that they are generally fabric specific. Some fluorescers work well on e.g. cotton, but not on polyester and vice versa.

The use of carrier material for better fluorescer deposition on to fabric is also disclosed in literature.

US2007/0203052 discloses a particulate fluorescer (brightener) wherein the carrier is urea formaldehyde, in order to deposit particulate brightener on to consumer articles during the wash WO00/58431 (Ciba) discloses the use of a brightener pigment comprising a cellulose powder which is dispersible in water and a water soluble fluorescent whitening agent for increasing the whiteness of cleansers or detergents.

DE 195 38 039 discloses a detergent in agglomerate form

characterized in that it contains at least one swellable layer silicate and at least one optical brightener in intimate contact with each other. DE 195 38 039 use swellable clay which are not anisotropic in terms of their surface characteristics.

US 5,449,402 discloses a functionally modified pigment particle is prepared by mixing a flocculated pigment of kaoline clay or calcium carbonate with a modifier having charge sites opposite in sign to the charge sites of the flocculated pigment. In US 5,449,402 the flocculated kaoline clay is first binded with a latex binder and then treated with modifier. This particle thus does not show anisotropic behaviour with respect to their surface property and thus not suitable for the present purpose.

All these documents do not provide a teaching for making a fluorescer with low fabric specificity and with improved retention on the fabric so that higher amount of fluorescer will stick to the fabric even after rinsing. This remains to be desired.

Furthermore in today' s polluting world and outdoor lifestyle most consumers want to protect and improve appearance of their skin and hair. That makes personal appearance/protection sector very important for consumer goods companies.

Consumers from different parts of the world have different colour characteristics of their skin. This is attributed to their genetic structure and geographical conditions. Some consumers want to lighten their skin, whereas other consumers want to get tanned. Consumers also want to protect their skin, hair and scalp from harmful UV rays while exposing themselves to sunlight.

There are several ways by which consumers may obtain protection from UV rays and also at the same time may improve their skin appearance .

Skin lighteners are known in the art and serve a useful purpose in the repertoire of cosmetics. Skin lightening agents are generally biochemically active molecules which help to modulate the melanin synthesis.

Photoprotection of skin from sunlight especially from UV rays is also known in the art. Sunscreens/sunblocks are generally used for this purpose. Sunscreens are generally organic molecules that absorb the UV light and emit the energy in a different form, for instance in the visible range of the spectrum or in the form of heat, thereby protecting the skin against sunburn. Similarly sunblocks help to protect the skin against possible sunburn. These sunblocks generally comprise inorganic particulates (like ZnO, Ti0₂) that reflect the incident rays in uv-visible region thus protecting the skin.

Formulations using these molecules in the form of a cream, a lotion, gel, or spray are known. Many consumers believe that the currently available sunscreens or skin lightening agents in cosmetics may penetrate inside the skin which is not desirable. Another problem associated with currently available sunscreens in cosmetics is that there are usually many other ingredients apart from sunscreens, with which they may interact thereby reducing their stability.

Obj ects :

In view of the foregoing, it is an object of the present invention to provide a fluorescer with improved retention to the fabric so that larger amounts of fluorescer will be

available even after rinsing.

It is therefore a further object of the present invention to provide a fluorescer with low fabric specificity. It is yet a further object of the invention to provide improved whiteness/brightness to fabrics and textiles.

It is yet a further object of the invention to provide a fluorescer with improved stability when formulated in personal care compositions.

It is yet a further object of the invention to provide improved skin appearance. It is still a further object of the invention to provide photoprotection of skin.

Surprisingly it has been found that fluorescer molecules tagged by surface reaction onto naturally occurring asymmetric clay surfaces, act as a fluorescer particle with improved retention properties, low fabric specificity, higher stability in

cosmetic formulations and/or yielding improved brightness and/or UV absorptions to substrate (skin/fabric) on use and meets at least one of the above mentioned objects.

Summary of the invention

Accordingly the present invention provides a bipolar

topospecific particulate fluorescer, which precursor is an asymmetric 1:1 or 2:1:1 clay particle comprising alternating tetrahedral and octahedral sheets terminating with a

tetrahedral sheet at one external surface plane and an

octahedral sheet at another external surface plane, with fluorescer molecules having excitation wavelength between 200- 500 nm selectively attached to the coordinating cations on one of the said external surface planes wherein said particulate fluorescer has anisotropic characteristics.

In another aspect, the invention provides a detergent

composition comprising particulate fluorescer of the invention. In another aspect the invention provides the use of the

particles according to the invention for increasing whiteness of fabrics and textiles.

In another aspect the invention provides a process of

preparation of bipolar particulate fluorescer which precursor is an asymmetric 1:1 or 2:1:1 clay particle comprising

alternating tetrahedral and octahedral sheets terminating with a tetrahedral sheet at one external surface plane and an octahedral sheet at another external surface plane, comprising the steps of (a) contacting the precursor with a mineral acid (b) adding a fluorescer molecule to the mixture (c) adjusting the pH to a range of between 2 and 10 and (d) heating the solution mixture at a temperature 50 - 150 °C and (e) separating the solid product comprising bipolar particulate fluorescer .

In another aspect the invention provides a process for

preparation of coated particle comprising the steps of (a) taking the solid bipolar fluorescer particle (b) adding it to a solvent containing the coating material at a temperature of 0°C to 100°C (c) stirring it for 10 minutes to 4 hours, (d) separating the coated particle, and (e) drying it at a

temperature of 25°C to 55°C.

In another aspect the invention provides a cosmetic composition comprising particulate fluorescer of the invention and a cosmetically acceptable base.

In another aspect the invention provides the use of particulate fluorescer for improving skin appearance.

In another aspect the invention provides the use of particulate fluorescer for photoprotection of skin.

Fluorescer molecules according to the present invention are defined as the group of molecules having an excitation

wavelength between 200-500 nm, wherein at least some electrons in the fluorescer molecule are brought from ground state to exited state induced by absorption of energy at the excitation wavelength .

These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description. For the avoidance of doubt, any feature of one aspect of the present invention may be utilised in any other aspect of the invention. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated.

Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be

understood as modified by the word "about". Numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated .

Detailed description of the invention Precursor

The precursor of the particle with bipolar topospecific

characteristics according to the present invention is an asymmetric 1:1 or 2:1:1 clay particle having alternating tetrahedral and an octahedral sheets terminating with a

tetrahedral and an octahedral sheet at exterior surface planes. Particle of 1:1 clay is particularly preferred as precursor.

According to the present invention preferred 1 : 1 clays include kaolinite and serpentine subgroups of minerals. The species included within the kaolinite subgroup include, but are not limited to, kaolinite, dickite, halloysite and nacrite.

The species within the serpentine subgroup include, but are not limited to chrysolite, lizardite, and amesite. According to the present invention preferred 2:1:1 clays include chlorite group of minerals. Chlorite is sometimes wrongly referred to as 2:2 clay by some mineralogists. The chlorite comprises tetrahedral-octahedral-tetrahedral sheets like 2:1 clays, with an extra weakly bound brucite like layer between tetrahedral layers.

The tetrahedral sheet preferably comprises coordinating

tetrahedral cations of silicon. The tetrahedral sheet may also comprise isomorphously substituted coordinating tetrahedral cations which are not silicon. Isomorphously substituted coordinating tetrahedral cations include, but are not limited to, cations of aluminium, iron or boron. The octahedral sheet preferably comprises coordinating

octahedral cation of aluminum. The octahedral sheet may also comprise isomorphously substituted coordinating octahedral cations which are not aluminium. Isomorphously substituted coordinating octahedral cations include cations of magnesium or iron.

It is preferred that the fluorescer molecule is attached to the coordinating cations on the exterior side of one of the

external surface planes. Accordingly, the fluorescer molecule is attached to coordinating cations on the exterior side of the tetrahedral sheet. Alternatively, the fluorescer molecule is attached to the coordinating cations on the exterior side of the octahedral sheet. According to a further aspect,

coordinating cations on the exterior side of each of the tetrahedral and the octahedral surface sheets are attached to a fluorescer molecule, with the proviso that the fluorescer molecule attached to the coordinating cations on the exterior side of the tetrahedral surface sheet is not identical to the molecule attached to the coordinating cations on the exterior side of the octahedral surface sheet.

The fluorescer molecule is preferably attached to the

coordinating cations on the external surface of the octahedral surface plane and is not preferably attached to coordination cations of non-exterior tetrahedral or octahedral plane or on the interior side of the surface sheets. To provide a brightening effect on detergent powder, fabrics or skin, excitation of ultra violet (UV) and/or yellow light and emission of light in the blue region of the spectrum is

preferred. The excitation (absorption) of light in the ultra violet (UV) and "yellow" regions of the spectrum (200-500 nm) and emission in the "blue" region of the spectrum (400-700), results in an optical brightening effect.

For a tanning effect, emission in the brown/red (550-700 nm) region of the spectrum is preferred.

For a sun blocking effect, the excitation in the UV region and emission outside the UV region, or even emission in the form of heat, is preferred. Further specifications of absorption and emission

characteristics are given here in below.

In the above mentioned particulate fluorescer the clay:

fluorescer ratio is between 1:0.001 and 1:0.1, more preferably between 1:0.01 and 1:0.05, most preferably about 1:0.018.

Process Any chemical reaction or series of reactions wherein a fluorescer molecule is attached selectively to coordinating cations on the exterior plane of either the tetrahedral or the octahedral surface plane of an asymmetric clay can be used to prepare the bipolar particulate fluorescer according to the present invention. In order to obtain a true bipolar fluorescer particle it is preferred that the reaction is selective to only one of the exterior planes. By selective is meant that more than 50% of the total fluorescer molecule is present on one of the exterior planes, preferably more than 75%, more preferably than 80%, still more preferably than 90%, even more preferably than 95%, or even more than 99%. The chemical reaction or series of reactions wherein the same fluorescer molecule attached to coordinating cations of both the surface sheets, viz octahedral and tetrahedral, are therefore not preferred.

The particle with bipolar characteristics may have two distinct regions on its surface having non-identical surface

characteristics. It is particularly preferred that the particle has two spatially distinct exterior faces having distinct surface characteristics. It is envisaged that by selecting specific fluorescer molecule having specific group, and

selectively attaching them to coordinating cations of

tetrahedral and/or octahedral surface sheets, it is possible to impart anisotropic characteristics of various types to the surface of particle with bipolar characteristics.

According to another aspect, the invention provides a process for preparing a bipolar particulate fluorescer which precursor is an asymmetric 1:1 or 2:1:1 clay particle having alternating tetrahedral and octahedral sheets terminating with a

tetrahedral sheet at one external surface plane and an

octahedral sheet at another external surface plane, comprising the steps of contacting the precursor with a mineral acid, adding a fluorescer molecule to the mixture, adjusting the pH of the solution in a range_between 2 to 10, heating the mixture to a temperature of 50 - 150 °C, and separating the solid product comprising bipolar particulate fluorescer. When temperatures greater than 100°C are applied, a pressure vessel is preferred.

Treating the precursor clay with a mineral acid

It is preferred that at first the raw clay is treated with a mineral acid preferably hydrochloric acid. The hydrochloric acid is used in a concentration range of 0.01 (N) to 1 (N) , preferably about 0.1 (N) . The clay particle with the acid is then stirred. The stirring is typically done for 10-60 minutes, preferably about 30 minutes.

Adding a desired fluorescer molecule After treating the clay with hydrochloric acid it is preferred that the desired fluorescer molecule is added to the

dispersion. The fluorescer molecules are then added in a concentration of 0.001 to 30 percent of the total weight of the dispersion, preferably 0.01 to 5%.

Adjusting the pH

After adding the fluorescer molecule the pH of the system is preferably adjusted to the desired pH as explained below.

In the process according to the invention, the reaction may be conducted in two different pH ranges. In one preferred process, the clay particle is treated with 0.1 N HC1. Then NaOH is added to increase the pH above 8. After that the desired fluorescer molecule is added. Then this dispersion mixture is heated, preferably for 4-8 hours, preferably about 6 hours with stirring at 70-90°C, preferably about 80°C. Finally the solid product comprising the bipolar particulate fluorescer particles is separated after washing it repeatedly with water and solvent. The solvent is preferably a ketone, most preferably acetone.

In another preferred process the kaolinite clay particle is treated with 0.1 N HC1. Then alkali is added to adjust the pH to between 2 to 4. After that the desired fluorescer molecule is added. Then this solution mixture is heated for 4-8 hours, preferably about 6 hours with stirring at 70-90°C, preferably about 80°C. Finally the solid product comprising the bipolar particulate fluorescer particles is separated after washing it repeatedly with water and solvent, preferably acetone. Heating the solution

After adding the fluorescer molecule and adjusting the pH of the dispersion, the solution is preferably heated for between 1 to 10 hours, preferably 4 to 8 hrs and more preferably about 6 hrs while stirring at 50°C to 150°C preferably 70°C to 90°C more preferably at 80°C.

Separating the solid product comprising the bipolar particulate fluorescer

After the reaction, the dispersion mixture is preferably centrifuged to obtain the bipolar fluorescer particle as residue. Then it is preferably washed with water and subsequently with a ketone solvent (e.g. acetone) . After that it is dried in an oven to get the final product.

In this reaction, fluorescer molecule is attached to the coordinating cations of the octahedral sheet preferable by covalent bonding. The particulate fluorescer made by this process has different wettability characteristics for two external surface planes.

Coated Fluorescer Particle

In a preferred embodiment the invention provides a bipolar particulate fluorescer coated with a coating material having a refractive index in the range of 1.3 to 2 preferably of 1.3 to 1.6. The selected coating material is preferably transparent to light in the wavelength range of 200 to 800 nm and is

preferably an organic compound. By transparent is meant that at least 50% of the light in the indicated wavelength is transmitted, preferably more than 75%, or even more than 90%. This coating material preferably has a surface energy between 10-200 ergs/cm², preferably between 20 - 50 ergs/cm². Examples of coating materials are aluminum hydroxide, fatty acid, silicone, polysaccharides and their derivatives.

The coating process may be carried out either in an aqueous or a non-aqueous solvent. The preferred solvents include water, acetone, ethanol and/or hexane . The process of making coated fluorescer particles preferably comprises the following steps:

(a) Preparing a solution of the coating material in an

aqueous or non-aqueous medium and optionally heating it to 25°C to 100°C to get the coating material dissolved in the solvent,

(b) adding the fluorescer particle to the solution medium, (c) stirring the mixture for 10 minutes to 4 hours,

preferably for 1 to 2 hours,

(d) separating the particles from the solvent, for instance by volatilizing the solvent (in case of a non-aqueous solvent) or by centrifugation (in case of an aqueous solvent) and

(e) drying the coated particles, e.g. in a hot air oven for

10 minutes to 2 hours at a temperature of 25 C to 55 C preferably at about 40°C.

The coated particle made from this process has uniform coating and uniform surface behaviour.

Fluorescer for laundry application

The present invention provides a detergent composition for improved whiteness of the fabrics and textiles. The particulate fluorescer is preferably delivered to the fabric by a detergent composition. This detergent composition is made by usual way of making any detergent formulation.

The emission wavelength of the fluorescer molecule is

preferably between 400-700nm more preferably between 400-500nm and most preferably between 420-470nm. The excitation

wavelength of the fluorescer molecule is preferably between 290-400 nm and more preferably between 345-355 nm.

This molecule is selected from the classes of Stilbene

derivatives, preferably Tinopal CBSX™, Benzthiazaole,

preferably Uivitex RS™, Fluorol derivatives, preferably Fluorol 5 GA™, Triazole Derivatives, Coumarin Derivatives, Benzoxazole Derivatives, Pyrazoline Derivatives, Anthyrozoline Derivatives, Benzocoumarin Derivatives, Oxazole Derivative and various combinations thereof for laundry application.

The particulate fluorescer is preferably incorporated in 0.01% to 10% by weight of the detergent composition. More preferred amount is from 0.1% to 5% by weight of the composition.

Different kinds of surfactants may also be included in the detergent composition. Anionic, cationic, nonionic or

zwitterionic surfactant or combinations thereof may be used in the detergent composition. In general, the surfactants of the surfactant system may be chosen from the surfactants described well known textbooks like "Surface Active Agents" Vol. 1, by Schwartz & Perry, Interscience 1949, Vol. 2 by Schwartz, Perry & Berch, Interscience 1958, and/or the current edition of

"McCutcheon ' s Emulsifiers and Detergents" published by

Manufacturing Confectioners Company or in

"Tenside-Taschenbuch" , H. Stache, 2nd Edn., Carl Hauser Verlag, 1981.

The surfactant is preferably incorporated to 50% by weight of the detergent composition, preferably at least 10% or even more than 15%, while generally less than 40% and even less than 30%. Although any concentration of surfactant may be used, suitable concentration is in the range of 0.5 to 3 grams per liter of the water after dissolution of the detergent

composition into 10-60 liters of water for washing.

Apart from that, builders may also be included in the detergent composition. Preferred builders include alkali metal

carbonates, borates, bicarbonates , silicates, sulphates and chlorides. Specific examples of such salts include sodium and potassium tetraborates, perborates, bicarbonates, carbonates, and sulphates. Phosphate builder (ex. STPP) may also be

included. The builder is preferably incorporated in 10% to 50% by weight of the detergent composition. Preferably 0% to 10% minors may also be incorporated in the detergent composition. These minors include perfumes, colours, pH modifier etc.

The detergent composition is suitable for any kind of laundry applications like hand-wash, machine-wash (with horizontal axis or vertical axis) and for any kind of fabric like cotton, polyester, polycotton etc.

Throughout this specification and claims, by the term

"detergent composition" is meant a composition for treatment or cleaning of fabric and includes compositions for use during main wash or for use during the rinse stage e.g. fabric

conditioners . Fluorescer for cosmetic application

The present invention provides a cosmetic composition for improved skin appearance and photoprotection of skin. The particulate fluorescer is preferably delivered to the skin through a cosmetic composition. This cosmetic composition is made by usual way of making any skin formulation.

For skin application sunscreen / skin brightening elements are preferably selected from p-Aminobanzoic acid, padimate 0™, Phenylbenzimidazole sulphonic acid, cinoxate, Dioxybenzone, Oxybenzone, Homosalate, Menthyl anthranilate, Octocrylene, Octyl methoxycinnamate, Octyl salicylate, Sulisobenzone,

Trolamine salicylate, Avobenzone, Ecamsule™, 4- Methylbenzylidene camphor, Tinosorb M™, Tinosorb S™, Tinopal CBSX™, Neo Heliopan AP™, Mexoryl XL™, Benzophenone-9, Uvinul T 150™, Uvinul A Plus™, Uvasorb HEB™, Parsol SLX™, Parsoll789™' , Isopentenyl-4-methoxycinnamate and combinations thereof

preferably p-aminobenzoic acid, Padimate 0™, Phenyl

benzimidazole sulfonic acid, Menthyl anthranilate,

Sulisobenzone, Trolomine salicylate, Ecamsule™, Tinosorb M™, Tinosorb S™, Neo heliopan AP™, Uvinul T 150™, Uvasorb HEB™, Homosalate, Octisalate, Oxybenzone, Avobenzone, Ensulizole, Octinoxate, Octocrylene and combinations thereof. Natural fluorescers such as curcumin are also included.

In the field of cosmetic use the preferred emission depends on the intended use. For sunscreens and sun blocks, the emission is preferably in the form of heat (or even as simple reflection of the radiation) .

For skin brightening applications, excitation in the range of 360-500nm is preferred; emission, the emission may be in any part of the visible light spectrum, preferably between 400 and 700 nm, more preferably between 400 and 600 nm, still more preferably between 400 and 550 nm.

For skin tanning applications, the excitation is preferably in the range of 360-500nm and emission is preferably in the range 500-700 nm, more preferably 550-700 nm, most preferably 600-700 nm.

For sun block application, the excitation is preferably at a wavelength in the range of 200-400 nm and emission in any form, including visible light (360-800nm) and/or heat. The particulate fluorescer is preferably incorporated in 0.05% to 10% by weight of the skin composition. More preferred amount is from 0.1% to 10%; most preferred amount is from 0.2 % to 5 % by weight of the composition.

Useful inorganic sun-blocks may also be additionally used in the compositions of the present invention. These include, for example, zinc oxide, iron oxide, silica, such as fumed silica, and titanium dioxide. The total amount of sun block that is preferably incorporated in the composition according to the invention is from 0.1 to 5% by weight of the composition.

A combination of particulate fluorescer and inorganic sun-block may be incorporated for better protection of skin which will cover a wide range of the UV and visible light spectra.

The skin cosmetic composition preferably comprises a

cosmetically acceptable vehicle to act as a diluent, dispersant or carrier for other materials present in the composition, so as to facilitate their distribution when the composition is applied to the skin. The concentrations of these in vanishing cream base is generally from 5%-25% by weight C₁2-C20 fatty acids and 0.1%-10% by weight fatty acid soap.

Vehicles other than water can include liquid or solid

emollients, solvents, humectants, thickeners and powders.

Examples of each of these types of vehicles can be used singly or as mixtures of one or more vehicles.

The compositions of the present invention may comprise a wide range of other optional components like antioxidants, binders, biological additives, buffering agents, colorants, thickeners, polymers, astringents, fragrance, humectants, opacifying agents, conditioners, exfoliating agents, pH adjusters,

preservatives, natural extracts, essential oils, skin sensates, skin soothing agents, and skin healing agents. Throughout this specification and claims, by the term "cosmetic composition" is meant a personal care composition. Such

compositions may be "leave ons", where the product is left to deliver actives/provide benefits on human substrate e.g. skin (including surfaces on face, hands, body, hair, lips, under arms) . Suitable leave-on compositions include skin creams, lotions, gels, hair treatment products, deodorants and

antiperspirants . Such personal care compositions also include "wash-off" products for cleaning surfaces of human body e.g. soaps, body wash, face wash, hand wash and shampoos.

Examples

The examples are for illustration only and do not limit the scope of the invention in any manner.

Example 1 : Preparation of fluorescer clay particles

3 g of kaolinite clay particle (commercially available as

Supershine 90 from English India China Clay) was treated with

0.1 N HC1. Alkali was added to adjust the pH between 2 to 4. 15 g of the desired fluorescer molecule (Tinopal CBSX, Disodium salt of 4,4-bis (2-disulfonic acid styryl) biphenyl) was added.

The dispersion was then heated for 6 hours with stirring at 80°C. The solid product comprising the bipolar particulate fluorescer particles was separated after washing it repeatedly with water and acetone.

Example 2: Characterization of the treated-clay particles

(a) UV light visualization The synthesized and untreated particles were taken on a black chart paper and spread evenly. The untreated sample serves as a point of reference. These black papers were visualized in a Macbeth Spectra light III viewing cabinet under a UV light. The reacted particles appeared bluish green under a UV light while the untreated particles appeared to be dull. This visual confirmation gives the initial proof of Tinopal being present on the clay. (b) Fluorescence microscopy

The synthesized and untreated particles were taken onto a glass slide and visualized using an Olympus (Provis AX70) microscope coupled with a NUA filter. The pictures were subjected to image analysis to determine the grey scale intensity using Image J (version 1.33U) software.

The Tinopal reacted particles were visible in fluorescence mode while the untreated clays were not visible. The results of image analysis are presented in table 1. The average grey scale intensity of the reacted particles is more than 150 while the background values are less than 10. Untreated clays had similar values as background. The higher intensity of the Tinopal-clay particles indicates the fluorescence of the particles while the intensity of the untreated particles being similar to the back ground indicates absence of fluorescence. Particles Grey Scale

intensity

Tinopal-Clay

Regionl 180.3

Region 2 199.2

Region 3 235.1

Untreated Clay

particle

Regionl 8.6

Region 2 8.0

Region 3 7.9

(c) Infrared spectroscopy

The reacted clay particles were subjected to Fourier

transformed infrared (FTIR) measurements (ex Perkin Elmer, Model no Spectrum-one diffuse reflectance mode using macrocup powder method) to determine the occurrence of the reaction. The infrared spectrum demonstrates that the Tinopal clay exhibits two distinct peaks at 1496 cm^-1 and 1469 cm^-1 as a contribution from C=C ring skeletal vibration. This peak was absent in untreated clays. The presence of Tinopal after repeated washing on the clay suggests that the Tinopal is bound to the clay surface.

(d) Fluorescence spectroscopy

The fluorescence spectroscopy of dilute aqueous

suspensions/solutions of molecular Tinopal (0.1 g/1) , Untreated Kaolinite (0.05g/l) and Kaolinite-Tinopal complex (0.05g/l) was performed using a Shimadzu RF 5301 PC fluorescence

spectrophotometer. The objective in this experiment is to determine whether the fluorescent molecule is bound to the clay surface. If the fluorescent molecule is attached with Kaolinite it would result in a shift of the spectra which is a reflection of the micro-environment of the fluorescent molecule.

The fluorescence spectrum exhibits that pure Kaolinite as expected does not have any fluorescence peak. The _max of the molecular Tinopal species is at 432 nm while the Tinopal-clay has a _max at 460 nm. Binding of a fluorescer ligand to a substrate is usually accompanied by a spectral shift. The shift in the spectra in this case suggests that the fluorescer is bound to the clay surface. Typically a fluorescer molecule has a larger dipole moment in the excited state. Upon excitation the clay surface can either relax or reorient the dipole moment, which lowers the energy of the exited state. This lowering of energy results in shifting of the emission peak to longer wavelengths. Thus the fluorescence spectroscopy

measurements suggest that the fluorescer molecule is bound to the clay surface.

Example 3: Comparison of Tinopal-clay particle with molecular fluorescer

Deposition, removal and quantification of retention of

molecular fluorescer:

0.5 ml of 0.27 g/1 of an aqueous solution of Tinopal was dosed using a micro pipette onto three cotton swatches (WFK, 10A, 10X10 cm) . The swatches were immediately transferred to a conical flask with 108 ml water (liquid to cloth ratio, L:C = 20) . The swatches were rinsed for 2 minutes at 90 rpm using a Haake SW B25 shaker bath at28°C. Then the fluorescence

intensity measurement was performed at 437 nm using Shimadzu RF 5301 PC fluorescence spectrophotometer. The concentration was calculated from a standard curve. The previously mentioned steps were repeated twice to estimate fluorescer loss at each rinse. The summation of three rinses gives the fluorescer loss after three rinses. The initial value of fluorescer added was also determined by dosing 0.5 ml of 0.27 g/litre Tinopal and determining its concentration using the standard curve. The concentration thus obtained was multiplied by three to

determine the total amount of fluorescer present initially.

Deposition, removal and quantification of retention of

particulate fluorescer:

0.5 ml of 1.3 g/1 of the particulate fluorescer molecule solution was dosed onto six cotton swatches (WFK, 10A and 10X10 cm) . Three swatches were immediately transferred to a conical flask with 108 ml water (L:C = 20) . Then the swatches were rinsed for 2 minutes at 90 rpm using a Haake SW B25 shaker bath at 28°C. Previously mentioned two steps were repeated twice. After that the fabrics were burned and ashed in a muffle furnace (ex. Thermolynl 48000) at 600 °C for 3 hrs . Then the ash was transferred to a small plastic container and weighed (ex Sartorius AG Germany model no CP 2250) . Three swatches were ashed without rinsing to determine the initial weight of the particulate fluorescer.

It was found that the average percentage retention (on the fabric) for molecular fluorescer is 33% whereas the average percentage retention (on the fabric) for particulate fluorescer is 73%. Example 4: Characterization of Tinopal-clay deposited fabrics: Effect of fabric specificity Swatches (10X1 Ocm) of cotton (WFK10A) and polyester (WFK 30A) were loaded with 0.5ml of 0.00432 gms/litre of Tinopal CBSX and dried at ambient temperature in the dark. Swatches (10X1 Ocm) of cotton (WFK10A) and polyester (WFK 30A) were loaded with 0.5ml of 20 gms/litre of particulate fluorescer of Example 1 and dried.

The fluorescence spectroscopes of the fabrics were determined using a Shimadzu RF 5301 PC fluorescence spectrophotometer by placing the fabrics onto a black template at an angle of 45 degree .

It was observed that the molecular fluorescer exhibited a shift in the _max as a function of fabric type. The polyester loaded fabrics exhibited a blue shift indicating that the Tinopal molecule has portioned onto a more hydrophobic surface. The particulate fluorescer on the other hand did not exhibit any shift in the values exhibiting less specificity towards various fabric type.

Example 5: Reflectance spectroscopy of Tinopal-clay particles

Reflectance spectroscopy of the particles provides information regarding the back scattering of the particles which is an important parameter governing photo protection involving particles. This experiment was performed by spreading 5 mg of the particles onto a circular area of 1.5 cm radius and

determining the reflectance spectra using a Macbeth 7000A reflectometer . The reflectance spectroscopy measurement shows that the

particles have a strong absorbance in the UV region compared to the untreated clay particles. This enhanced absorption of the particles suggests that these particles would be effective against protection from UV light. The scattering of the

particles is also modified as evidenced from the reflectance spectroscopy with a of the system at 440 nm in comparison to untreated particles which has a featureless spectrum.

Example 6: Skin cream formulation with Tinopal clay particles

The following formulation was prepared using Tinopal clay particles. The Clay particles along with other water phase ingredients (except KOH) was taken and stirred for 30 minutes at a temperature of 80°C. A solution of KOH (potassium

hydroxide) was prepared separately, heated to 80 °C and added to the water phase under stirring. The oil phase ingredients were heated separately (80°C) in two parts. One of the parts had only stearic acid as the ingredient while the other part had rest of the oil phase ingredients. Stearic acid was added to the water phase under stirring and the emulsion was allowed to be formed. The other oil phase ingredients were added next and allowed to mix for 30 minutes while bringing the temperature of the mixture gradually to cool to room temperature. It was observed that on addition of the particles the sensory of the formulation was not compromised and no major difficulty was observed while preparing the formulation. Ingredients (Wt %)

Water 76

Glycerin 1

Methyl Paraben 0.2

EDTA 0.004

KOH 0.569

Tinopal-Clay 3

particles

Titanium dioxide 0

Sunscreen 0

Stearic Acid 17

Cetyl alcohol 0.530

IPM 0.750

DC-200/350 0.500

Propyl paraben 0.100

Phenoxy ethanol 0.200

Colour 0.100

Perfume 0.000

Example 7 : Efficacy of the Tinopal reacted clay with respect to the unreacted clay in terms of their UV protection

Amigel ( Alban Muller International) , a vegetable based gelling agent derived from the yeast of Sclerotium rolfsii is used as a gelling agent. 2% w/v of gellent was slowly added to deionized water under magnetic stirring and it was stirred for 1-2 hours to develop enough viscosity.

10% w/w of pure clay and Tinopal reacted clay were suspended separately in deionized water. To this 2% w/v of gellent was added under magnetic stirring for 1-2 hours to develop

sufficient viscosity.

After that the samples were prepared for measuring

transmittance spectrum as follows: a) 5cm x 5cm quartz plates were taken and on top of which Transpore (3M) tape was pasted.

b) 3mg /sq.cm of control and samples were taken separately and were spread uniformly on top the Transpore tape.

c) Visible cutoff filter was placed on the top the detector and the sample was placed on top of the filter

d) Transmittance spectrum was measured by irradiating the

sample at 250mW intensity. It was observed that Tinopal reacted clay was capable of absorbing much more UV light than unreacted clay or base gel.

Example 8: Coating process for bipolar fluorescer particles In non-aqueous solvent

O.Olg of cellulose acetate was dissolved in 25 ml of acetone. 0. lg of particulate fluorescer was dispersed by mixing it in a vortex mixer. The solution was then stirred until all the acetone was volatilized. The coated particles were dried in an air oven at 40°C for 1 hour.

In aqueous solvent

1% to 5% by weight of starch solution was prepared at 80°C. lg of particulate fluorescer was dispersed in 30 ml of the starch solution. The solution was then stirred for about 1 to 2 hour. After that the solution was cooled down to room temperature (25°C) . The coated particles were separated from the solution by centrifugation and then dried it in an air oven at 40°C for an hour.

Example 9: Comparison of retention between molecular fluorescer versus fluorescer particle of the invention. Tinopal CBSX is taken as the molecular fluorescer for this purpose and Tinopal CBSX reacted clay particle is the fluorescer particle of the invention (see above for synthesis) . ImL of lOgpL Tinopal CBSX solution is dosed over hydroxyapatite tile (15mm x 15mm x 5 mm; ex IFGL Bio Ceramics Ltd Kolkata; a common model tooth surface) and kept for 1 min. 19mL of deionized water is added to this and rinsed for 1 min in shaker bath (Orbital Shaking Incubator Model ACM-22065-I) at 180 rpm. The rinsing step is repeated twice with 20 mL of deionized water each. Then reflectance spectroscopy is used to determine the concentration of Tinopal CBSX on the tiles.

It is found that more than 90% of Tinopal CBSX is removed after rinsing .

Similarly ImL of 5gpL Tinopal CBSX-clay suspension is dosed over hydroxyapatite tile and kept for lmin. 19mL of deionized water is added to this and rinsed for 1 min in shaker bath (Orbital Shaking Incubator Model ACM-22065-I) at 180 rpm. The rinsing step is repeated twice with 20 mL of deionized water each. Then reflectance spectroscopy is used to determine the concentration of Tinopal CBSX on the tiles.

It is shown that more than 90% of fluorescer particle of the invention is retained on the tile after rinsing.

Claims

1 A bipolar topospecific particulate fluorescer,

a which precursor is an asymmetric 1:1 or 2:1:1 clay

particle comprising alternating tetrahedral and octahedral sheets terminating with a tetrahedral sheet at one external surface plane and an octahedral sheet at another external surface plane,

b with fluorescer molecules having excitation wavelength between 200-500 nm selectively attached to the coordinating cations on one of the said external surface planes

wherein said particulate fluorescer has anisotropic characteristics .

2 A particulate fluorescer as claimed in claim 1 wherein said fluorescer molecule is attached to coordinating cations on the external surface of the octahedral surface plane.

3 A particulate fluorescer as claimed in any one of the

preceding claims wherein the said fluorescer molecule is selected from the classes of Stilbene derivatives, ,

Benzthiazaole, Fluorol derivatives, Triazole Derivatives, Coumarin Derivatives, Benzoxazole Derivatives, Pyrazoline Derivatives, Anthyrozoline Derivatives, Benzocoumarin

Derivatives, Oxazole Derivatives and combinations thereof or p-Aminobanzoic acid, padimate 0™, Phenylbenzimidazole sulphonic acid, cinoxate, Dioxybenzone, Oxybenzone,

Homosalate, Menthyl anthranilate, Octocrylene, Octyl methoxycinnamate, Octyl salicylate, Sulisobenzone,

Trolamine salicylate, Avobenzone, Ecamsule™, 4- Methylbenzylidene camphor, Tinosorb M™, Tinosorb S™, Tinopal CBSX™, Neo Heliopan AP™, Mexoryl XL™, Benzophenone-9, Uvinul T 150™, Uvinul A Plus™, Uvasorb HEB™, Parsol SLX™, Parsol 1789™' , Isopentenyl-4- methoxycinnamate, Ensulizole, Octinoxate, and combinations thereof A particulate fluorescer as claimed in any one of the preceding claims wherein clay: fluorescer ratio is of

1:0.001 to 1:0.1. A bipolar particulate fluorescer as claimed in claim 1 to 4 wherein the particle is coated with a coating material having a refractive index in the range of 1.3 to 2. A particulate fluorescer as claimed in claim 5 wherein said coating material is aluminum hydroxide, fatty acid, silicone, polysaccharides and their derivatives. A detergent composition comprising a particulate fluorescer as claimed in any one of the preceding claims. A detergent composition as claimed in claim 7 wherein the fluorescer particle is in the range of 0.1-5% by weight of the composition. A cosmetic composition comprising;

a particulate fluorescer as claimed in any one of the

preceding claims 1 to 4 ; and

b a cosmetically acceptable base. A cosmetic composition as claimed in claimed in claim 9 wherein the cosmetically acceptable base is a cream, lotion, gel or emulsion. A process for preparing bipolar particulate fluorescer which precursor is an asymmetric 1:1 or 2:1:1 clay particle having alternating tetrahedral and octahedral sheets terminating with a tetrahedral sheet at one external surface plane and an octahedral sheet at another external surface plane, comprising the steps of:

a contacting the precursor with a mineral acid,

b adding a fluorescer molecule to the mixture,

c Adjusting the pH of the solution to a range between 2 to 10

d heating the mixture to a temperature of 50 - 150 °C, and

e Separating the solid product comprising bipolar

particulate fluorescer. A process as claimed in claim 11 wherein the precursor is selected from kaolinite, dickite, halloysite and nacrite, chrysolite, lizardite, and amesite or combinations thereof. A process as claimed in claim 11 further comprising the steps of:

a taking the solid bipolar fluorescer particle,

b adding it to a solvent containing the coating material at a temperature of 25°C to 100°C,

c stirring it for 10 minutes to 4 hours,

d separating the coated particle, and

e drying it at a temperature of 25°C to 55°C. Use of clay particle according to any one of the claims 1 to 4 for increasing whiteness of fabrics. Use of particulate fluorescer as claimed in any one of the preceding claims 1 to 6 for improved skin appearance or photoprotection of skin.