Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q17/00—Barrier preparations; Preparations brought into direct contact with the skin for affording protection against external influences, e.g. sunlight, X-rays or other harmful rays, corrosive materials, bacteria or insect stings
  • A61Q17/04—Topical preparations for affording protection against sunlight or other radiation; Topical sun tanning preparations
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/02—Cosmetics or similar toiletry preparations characterised by special physical form
  • A61K8/11—Encapsulated compositions
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/30—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds
  • A61K8/33—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds containing oxygen
  • A61K8/35—Ketones, e.g. benzophenone
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/30—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds
  • A61K8/33—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds containing oxygen
  • A61K8/37—Esters of carboxylic acids
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/30—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds
  • A61K8/58—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds containing atoms other than carbon, hydrogen, halogen, oxygen, nitrogen, sulfur or phosphorus
  • A61K8/585—Organosilicon compounds
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P17/00—Drugs for dermatological disorders
  • A61P17/04—Antipruritics
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q19/00—Preparations for care of the skin
  • A61Q19/10—Washing or bathing preparations
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q5/00—Preparations for care of the hair
  • A61Q5/02—Preparations for cleaning the hair
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q5/00—Preparations for care of the hair
  • A61Q5/12—Preparations containing hair conditioners
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
  • B01J13/02—Making microcapsules or microballoons
  • B01J13/06—Making microcapsules or microballoons by phase separation
  • B01J13/14—Polymerisation; cross-linking
  • B01J13/18—In situ polymerisation with all reactants being present in the same phase
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
  • B01J13/02—Making microcapsules or microballoons
  • B01J13/20—After-treatment of capsule walls, e.g. hardening
  • B01J13/206—Hardening; drying
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K2800/00—Properties of cosmetic compositions or active ingredients thereof or formulation aids used therein and process related aspects
  • A61K2800/40—Chemical, physico-chemical or functional or structural properties of particular ingredients
  • A61K2800/41—Particular ingredients further characterized by their size
  • A61K2800/412—Microsized, i.e. having sizes between 0.1 and 100 microns

Definitions

• This invention relates to a process for encapsulating materials such as cosmetic, chemical or pharmaceutical active material compositions and to the encapsulated compositions which can be formed thereby. It is of particular use in encapsulating sunscreen active materials and can also be used for other cosmetic actives, such as perfumes, for other chemical materials and for pharmaceutical active materials.
• the cosmetic active material may be present in high amounts.
• a SPF (sun protection factor) 15 sun cream or lotion may contain over 5% by weight sunscreen active materials (UV blockers).
• sunscreen active materials UV blockers
• JP-A-2-2867 describes sunscreen benzophenone derivatives encapsulated in fine spherical silica particles.
• the sunscreen is dissolved in aqueous alkali metal silicate solution and is emulsified in an organic non-solvent to form a water-in-oil emulsion.
• the emulsion is acidified to form a water-insoluble precipitate of sunscreen encapsulated in silica.
• the process of JP-A-2-2867 is suitable for hydrophilic sunscreen active materials, but most sunscreen active materials are lipophilic.
• WO-A-98/31333 describes sunscreen-doped sol-gel materials and a method for their preparation comprising condensation polymerising a metal or semi-metal alkoxide or ester in the presence of at least one sunscreen ingredient, resulting in the entrapment of the sunscreen ingredients within the formed sol-gel matrix.
• US-A-6303149 describes a process for preparing sol-gel microcapsules loaded with functional molecules by emulsifying sol-gel precursors and the functional molecules in an aqueous solution, and mixing the emulsion with an acidic, neutral or basic aqueous solution to obtain a suspension of microcapsules.
• US-A-6238650 describes a sunscreen composition comprising at least one sunscreen active ingredient and a cosmetically acceptable vehicle, wherein said sunscreen active ingredient is in the form of sol-gel microcapsules containing at least one sunscreen compound.
• the sol-gel microcapsules are prepared by the method disclosed in US-A-6303149.
• EP-A-281034 describes a perfume encapsulated and/or clathrated in a matrix of inorganic polymer prepared from a metal alkoxide such as tetraethyl orthosilicate (TEOS).
• a metal alkoxide such as tetraethyl orthosilicate (TEOS).
• TEOS tetraethyl orthosilicate
• An aqueous dispersion or solution of perfume and TEOS is treated with an acid catalyst to cause hydrolysis, then with a base catalyst to cause polymerisation to a gel.
• EP-A-941761 describes a process for preparing microcapsules with an organopolysiloxane shell and a core material, in which the shell is formed in situ by hydrolysis and polycondensation of an organosilane and/or a condensation product thereof having at most 4 silicon atoms.
• JP-51-78995-A describes dispersing a silyl-treated pigment with TEOS in acetone and adding to ammoniacal aqueous ethanol with stirring to form a micropowder of particles having a pigment core.
• WO-A-00/71084 describes preparing a sunscreen composition with improved photostability that contains at least two sunscreen actives which are photo-unstable when formulated together by microencapsulating at least one of the actives and adding other components of the sunscreen composition.
• WO-A-01/80823 describes a therapeutic or cosmetic composition comprising microcapsules of diameter 0.1-100 ⁇ having a core-shell structure.
• the core includes at least one active.
• the shell comprises an inorganic polymer obtained by a sol-gel process, and releases the active after topical application.
• a process for encapsulating a lipophilic cosmetic, chemical, biological or pharmaceutical active material composition is characterised in that a water reactive silicon compound comprising tetraalkoxysilane is added to an aqueous emulsion of the active material composition having a positive zeta-potential, whereby the tetraalkoxysilane condenses and polymerises at the interface of the droplets in the emulsion to form microcapsules having a core of the active material composition surrounded by a shell of silicon-based network polymer.
• 'emulsion ' to mean a liquid in liquid dispersion and 'suspension' to mean a solid in liquid dispersion.
• the invention also includes an encapsulated cosmetic, chemical, biological or pharmaceutical active material composition, characterised in that the encapsulated composition comprises microcapsules of a lipophilic cosmetic, chemical, biological or pharmaceutical active material composition encapsulated within a shell of the emulsion polymerisation product of a tetraalkoxysilane.
• the invention also includes a process for the preparation of an encapsulated lipophilic cosmetic, chemical, biological or pharmaceutical active material composition, characterised in that an aqueous emulsion of the active material composition is mixed with a water-reactive silicon compound, thereby forming a suspension of microcapsules having a core of the active material composition and a shell of silicon-based network polymer, and the microcapsules are post-treated with a water-reactive metal alkoxy or acyloxy compound.
• the tetraalkoxysilane such as tetraethoxysilane (TEOS) can be used in monomeric form or as a liquid partial condensate.
• TEOS tetraethoxysilane
• the tetraalkoxysilane can be used in conjunction with one or more other water-reactive silicon compound having at least two, preferably at least 3, Si-OH groups or hydrolysable groups bonded to silicon, for example an alkyltrialkoxysilane such as methyltrimethoxysilane or a liquid condensate of an alkyltrialkoxysilane.
• Hydrolysable groups can for example be alkoxy or acyloxy groups bonded to silicon.
• the water reactive silicon compound can for example comprise 75-100% by weight tetraalkoxysilane and 0-25% trialkoxysilane.
• the alkyl and alkoxy groups in the tetraalkoxysilanes or other silanes preferably contain 1 to 4 carbon atoms, most preferably 1 or 2 carbon atoms.
• the tetraalkoxysilane, and other water-reactive silicon compound if used, hydrolyses and condenses to form a network polymer, that is a 3 -dimensional network of silicon-based material, around the emulsified droplets of the lipophilic active material composition.
• the water-reactive silicon compound preferably consists of at least 75%, and most preferably 90-100% tetraalkoxysilane. We have found that a tetraalkoxysilane is the most effective silicon compound for forming impermeable microcapsules, forming a 3- dimensional network consisting substantially of SiO 4/2 units.
• the lipophilic cosmetic, chemical, biological or pharmaceutical active material composition is a liquid at the time it is emulsified and usually is liquid at ambient temperature. It can be an undiluted liquid active material or can be a solution of an active material in a lipophilic solvent, preferably a non- volatile solvent, or a water-in-oil or oil-in- water-in-oil emulsion, or a lipophilic suspension. Solid active materials can be melted before being emulsified if their melting temperature is significantly below lOOoC.
• the active material can for example be a sunscreen.
• Sunscreen active compounds which are used in the invention can for example be UV-B blockers such as 2- ethylhexyl methoxycinnamate, generally known as octyl methoxycinnamate or UV-A blockers such as butylmethoxydibenzoylmethane known as avobenzone.
• Mixtures of sunscreen compounds can be used, for example a mixture of octyl methoxycinnamate with octocrylene, although octyl methoxycinnamate and avobenzone are known to be photolytically unstable when mixed in high concentrations and should preferably not be encapsulated together.
• Octyl methoxycinnamate is liquid and can be used undiluted.
• Butylmethoxydibenzoylmethane is a solid which can be dissolved in an inert lipophilic liquid.
• Sunscreen active compounds can perform their function of screening out harmful UV radiation while they are encapsulated.
• the silicon-based polymer forming the shell of the microcapsules does not absorb UV and has no negative impact on the sunscreen efficiency, and may potentially improve the protection against photodegradation.
• An encapsulated sunscreen according to the invention preferably has a substantially impermeable silicon-based polymer shell.
• the active material composition which is mixed with the water reactive silicon compound may comprise a diluent as well as the active perfume or fragrance compounds.
• the diluent is preferably odourless and non-volatile and can for example be a non-reactive polydiorganosiloxane or a nonvolatile liquid hydrocarbon or ester.
• a permanent shell is not required. The shell may be breakable, for example brittle, so that the microcapsules are broken under the application of shear, releasing the perfume. Larger particles of diameter at least 10 ⁇ m, for example 50 ⁇ m or above, are more readily breakable than smaller particles.
• UV absorbers for use in coatings, paints, plastics materials, sealants or textile finishes to improve weatherability and resist fading
• such UV absorber compositions are preferably encapsulated in an impermeable silicon-based polymer shell
• Pharmaceuticals and related health products such as vitamins can be encapsulated in a silicon-based polymer shell which is broken down in the body after ingestion of the pharmaceutical.
• Biological (including biochemical) materials such as proteins, enzymes and cells can similarly be encapsulated.
• Radioactive material can be encapsulated for cancer treatment. Water insoluble liquid chemical materials can be protected, for example during storage or transport. Encapsulation can alternatively be used to modify the surface properties, optical properties or feel and taste of any core material.
• the lipophilic active material composition is emulsified in an aqueous medium preferably with the aid of a surfactant.
• the particle size of the emulsion of active material composition is generally in the range 0.01 to 500, preferably 0,1 to 50 micrometres.
• the emulsion can alternatively be a microemulsion of particle size 10-150 nm.
• the surfactant is most preferably a cationic or amphoteric surfactant, which readily forms an emulsion of positive zeta-potential.
• Nonionic surfactants can be used; for example the cationic or amphoteric surfactant can be mixed with up to an equal weight of nonionic surfactant.
• the concentration of surfactant in the aqueous emulsion of lipophilic active material can be between 0.01 and 10% by weight, but is preferably at least 0.02% and below 2%, most preferably 0.05 to 1.5% by weight of the emulsion, particularly 0.2-1.0%.
• concentration of surfactant in the aqueous emulsion of lipophilic active material can be between 0.01 and 10% by weight, but is preferably at least 0.02% and below 2%, most preferably 0.05 to 1.5% by weight of the emulsion, particularly 0.2-1.0%.
• the weight ratio of oil phase to aqueous phase in the emulsion can generally be between 40:1 and 1:50, although the higher proportions of aqueous phase are economically disadvantageous particularly when forming an emulsion of microcapsules.
• the weight ratio of oil phase to aqueous phase is between 2:1 and 1:3.
• a phase inversion process can be used in which the oil phase is mixed with surfactant and a small amount of water, for example 2.5 to 10% by weight based on the oil phase, forming a water-in-oil emulsion which inverts to an oil-in- water emulsion as it is sheared. Further water can then be added to dilute the emulsion to the required concentration.
• Examples of cationic surfactants include quaternary ammonium hydroxides such as octyl trimethyl ammonium hydroxide, dodecyl trimethyl ammonium hydroxide, hexadecyl trimethyl ammonium hydroxide, octyl dimethyl benzyl ammonium hydroxide, decyl dimethyl benzyl ammonium hydroxide, didodecyl dimethyl ammonium hydroxide, dioctadecyl dimethyl ammonium hydroxide, tallow trimethyl ammonium hydroxide and coco trimethyl ammonium hydroxide as well as corresponding salts of these materials, fatty amines and fatty acid amides and their derivatives, basic pyridinium compounds, quaternary ammonium bases of benzimidazolines and polypropanolpolyethanol amines. Cationic emulsions of microcapsules have increased deposition of the microcapsules from the emulsion and
• amphoteric surfactants include cocamidopropyl betaine, cocamidopropyl hydroxysulfate, cocobetaine, sodium cocoamidoacetate, cocodimethyl betaine, N-coco-3-arninobutyric acid and imidazolinium carboxyl compounds.
• the above surfactants may be used individually or in combination.
• non-ionic surfactants include polyoxyalkylene alkyl ethers such as polyethylene glycol long chain (12-14C) alkyl ether, polyoxyalkylene sorbitan ethers, polyoxyalkylene alkoxylate esters, polyoxyalkylene alkylphenol ethers, ethylene glycol propylene glycol copolymers, polyvinyl alcohol and alkylpolysaccharides, for example materials of the structure R 1 -O-(R 2 O) m -(G) n wherein R 1 represents a linear or branched alkyl group, a linear or branched alkenyl group or an alkylphenyl group, R represent an alkylene group, G represents a reduced sugar, m denotes 0 or a positive integer and n represent a positive integer as described in US Patent 5,035,832.
• polyoxyalkylene alkyl ethers such as polyethylene glycol long chain (12-14C) alkyl ether, polyoxyalkylene sorbit
• the continuous phase of the emulsion can be a mixture of water with a water- miscible organic solvent such as an alcohol or lactam provided that the continuous phase is not miscible with the lipophilic active material.
• the particle size of the emulsion of lipophilic active material can be reduced before addition of the water-reactive silicon compound, for example in an apparatus applying increased shear such as a homogeniser or microfluidiser, or a sonolator (ultrasonic mixer), producing an emulsion of microcapsules of particle size 100-1000 nm, most preferably between 200 nm and 500 nm.
• the emulsion can alternatively be prepared by phase inversion.
• the particle size of the microcapsules produced generally corresponds to the particle size of the starting emulsion and can for example be in the range 0.01-500 ⁇ m, most preferably 200 nm to 10 ⁇ m. For some uses, microcapsules of particle size 1-500 ⁇ m, particularly up to 50 or 100 ⁇ m, may be preferred.
• the aqueous phase of the emulsion preferably contains a thickener, for example polyvinylpyrrolidone, polyvinyl alcohol, bentonite clay, a cellulose derivative, particularly a cellulose ether such as sodium carboxymethylcellulose, a lightly crosslinked acrylic polymer, modified starch, an alginate or xanthan gum, to inhibit settling of the microcapsules from the emulsion during formation or subsequently.
• a thickener for example polyvinylpyrrolidone, polyvinyl alcohol, bentonite clay, a cellulose derivative, particularly a cellulose ether such as sodium carboxymethylcellulose, a lightly crosslinked acrylic polymer, modified starch, an alginate or xanthan gum, to inhibit settling of the microcapsules from the emulsion during formation or subsequently.
• the thickener is added to the emulsion before addition of the tetraalkoxysilane.
• the tetraalkoxysilane, and other water reactive silicon compound if used can be added to the emulsion of active material composition as an undiluted liquid or as a solution in an organic solvent or in an emulsion form.
• the tetraalkoxysilane and the emulsion are generally mixed under shear during addition and subsequently during condensation to form the silicon-based polymer shell on the surface of the emulsified droplets.
• the condensation reaction can be conducted at acidic, neutral or basic pH.
• the condensation reaction is generally carried out at ambient temperature and pressure, but can be carried out at increased temperature, for example up to 95oC, and increased or decreased pressure, for example under vacuum to strip the volatile alcohol produced during the condensation reaction.
• the weight ratio of active material composition to water reactive silicon compound is preferably at least 0.5:1 and in many cases maybe at least 1.5:1, for example 2: 1 to 9: 1. Smaller microcapsules, for example those formed from a microemulsion, generally have a lower ratio of active material composition to water reactive silicon compound.
• a catalyst for hydrolysis and/or condensation of the water reactive silicon compound to form the silicon-based polymer may be used.
• the catalyst is preferably an oil soluble organic metal compound, for example an organic tin compound, particularly an organotin compound such as a diorganotin diester, for example dimethyl tin di(neodecanoate), dibutyl tin dilaurate or dibutyl tin diacetate, or alternatively a tin carboxylate such as stannous octoate, or an organic titanium compound such as tetrabutyl titanate.
• An organotin catalyst can for example be used at 0.05 to 2% by weight based on the water reactive silicon compound.
• An organotin catalyst has the advantage of effective catalysis at neutral pH.
• a catalyst is most preferably mixed with the lipophilic cosmetic, chemical or pharmaceutical active material composition before it is emulsified, since this promotes condensation of the water reactive silicon compound at the surface of the emulsified lipophilic droplets.
• a catalyst can alternatively be added to the emulsion before the addition of the water-reactive silicon compound, or simultaneously with the water-reactive silicon compound, or after the addition of the water-reactive silicon compound to harden and make more impervious the shell of silicon-based polymer which has been formed.
• Encapsulation can however be achieved without catalyst, and we have found in some cases that microcapsules formed with a low level of catalyst or no catalyst are more resistant to diffusion or leaching of the lipophilic active material from the microcapsules.
• the catalyst when used, can be added undiluted, or as a solution in an organic solvent such as a hydrocarbon, alcohol or ketone, or as a mutiphasic system such as an emulsion or suspension.
• the product of hydrolysis and condensation of the water reactive silicon compound is an aqueous suspension of microcapsules.
• the aqueous continuous phase can contain water miscible organic solvent; for example it usually contains an alcohol such as ethanol generated by hydrolysis of Si-bonded alkoxy groups.
• a suspension of encapsulated sunscreen can be incorporated direct into a sunscreen lotion or cream or can even be used itself as a sunscreen lotion.
• the suspension of encapsulated sunscreen can be used in conjunction with other sunscreens, if desired.
• an encapsulated UV-B absorber such as octyl methoxycinnamate can be formulated with a UV-A absorber such as avobenzone and optionally with other sunscreens.
• the UV-A absorber in such a formulation can be free or encapsulated.
• microcapsules For many uses it may be preferred to recover the microcapsules from suspension, for example for subsequent dispersion in a different medium.
• An encapsulated sunscreen can for example be dispersed in a water based cosmetic preparation, preferably in such a proportion that the content of sunscreen in the cosmetic preparation is 0.1 to 10% by weight.
• the microcapsules can be redispersed in an organic solvent, optionally with additives such as surfactant and/or polymer. Recovery of the microcapsules can be achieved by any known liquid removal technique, for example by spray drying, spray chilling, filtering, oven drying or lyophilisation.
• encapsulated sunscreens according to the invention are in fabric treatment, for example the suspension of microcapsules or the separated microcapsules can be incorporated in a fabric softener to inhibit subsequent colour fading of the fabric, or in plastics compositions or coatings which are designed to be exposed to sunlight or UV light in use.
• the encapsulated product can be post-treated with a water-reactive metal alkoxy or acyloxy compound.
• the metal compound should be gradually hydrolysed in water rather than immediately reacting with water; compounds of Group IVB, TVA or VA of the Periodic Table are suitable such as compounds of silicon, titanium, zirconium or vanadium.
• the water-reactive metal alkoxy or acyloxy compound can for example harden the shell of the microcapsules and/or make them more impermeable.
• the reactive metal alkoxy or acyloxy compound can for example be an alkoxysilane or acyloxysilane, particularly a trialkoxysilane such as methyl triethoxy silane or isobutyl triethoxy silane, or a silane having Si-H functionality such as tris(dimethylhydrogensilyloxy) n-octyl silane, or alternatively a titanium alkoxide (alkyl titanate).
• the reactive metal alkoxy or acyloxy compound can have an organic functional group to promote adhesion to substrates, especially textile substrates, for example 3-methacryloxypropyl trimethoxy silane, 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxy silane, 3-glycidoxypropyl trimethoxy silane and 3-(2-aminoethylamino)propyl trimethoxy silane.
• the microcapsules can be post-treated with a reactive metal alkoxy or acyloxy compounds, e.g. an alkoxysilane to change their physical and/or chemical properties, for example by making the capsule surface more hydrophobic or more hydrophilic.
• the microcapsule surface can be made more hydrophobic by reaction with a silane having a long chain alkyl group such as octyl triethoxy silane.
• the microcapsules can be coated with a material which alters their surface properties. The surface treatment can be carried out on the microcapsules in suspension or on the separated solid microcapsules.
• microcapsules according to the invention inhibit diffusion or leaching of the lipophilic cosmetic, chemical, biological or pharmaceutical active material from the microcapsules.
• rate of diffusion or leaching is as low as possible.
• a controlled rate of release may be preferred, and this can be achieved by adjusting the level of surfactant, the level of tetraalkoxysilane and optionally of trialkoxysilane, the particle size and the level of catalyst.
• Microcapsules according to the invention containing cosmetic active material compositions, including sunscreens have good skin adhesion.
• the microcapsules minimise contact between the sunscreen and the skin, resulting in decreased penetration and consequently less potential irritation and allergy.
• the emulsion of microcapsules can have a high concentration of sunscreen (high pay load) compared to an aqueous dispersion of sunscreen, increasing the ease of use of lipophilic sunscreens in surfactant based product and allowing the sunscreen preparation to have a very liquid product form, which may be sprayable.
• Encapsulation eliminates the greasy feel associated with lipophilic sunscreens, increasing the acceptability and use in skin care products.
• the microcapsule does not affect the photostability of the encapsulated sunscreen.
• Exposure for 20 minutes to irradiation by a 19 mW/cm UV A lamp and a 0.6 mW/cm UV B lamp gives less than 10% reduction in the sun protection factor of an encapsulated octyl methoxycinnamate composition.
• the silicon-based polymer forming the shell of the microcapsules generally remains water insoluble even in the presence of surfactant, so that the encapsulated cosmetic active can be used in water based toiletry preparations including surfactant based products such as hair shampoo, conditioner or colourant, textile softener, detergent or shower gel.
• octylmethoxycinnamate (OMC, a UV-B sunscreen oil) was emulsified in 53.1 g water containing 1.64g Volpo L3 (Trade Mark) nonionic polyethylene glycol lauryl ether surfactant and 3.66g Arquad 16-29 (Trade Mark) cetyl trimethyl ammonium chloride cationic surfactant.
• the coarse emulsion was passed twice through a "Rannie Mini Lab 8.30 H" homogeniser operating at 950 bars. 17.71g TEOS was added to the emulsion while stirring to form a coarse emulsion of microcapsules.
• Microcapsules of median diameter 372nm were produced in suspension. When the microcapsules were tested using a leaching procedure to extract non-encapsulated oil, the degree of encapsulation was 97%.
• Example 1 was repeated with the addition of 0.236g dimethyltin dineodecanoate catalyst just after the TEOS. Microcapsules of median diameter 372nm were produced with an encapsulation yield of 89%. The suspension of microcapsules had an OMC content of 35.1% and the separated microcapsules had an OMC content of 89%.
• Table 1 shows that the encapsulation does not have any negative impact on the sunscreen efficiency and could even have a positive impact.
• the resistance of the encapsulated sunscreens of Examples 1 and 2 to leaching of OMC from the microcapsules was tested by an aggressive method in which the suspension of microcapsules was dispersed at 1% in a paraffinic solvent and the OMC content of the paraffin was measured by UV spectroscopy at different time intervals after dispersion. The concentration of OMC in the paraffin was found to increase in a linear manner with time (zero order delivery of OMC). In this test, 47% of the OMC was extracted from the microcapsules of Example 1 after 24 hours and 71% of the OMC was extracted from the microcapsules of Example 2 after 24 hours. Without encapsulation, over 80% of the OMC is extracted from the emulsion of OMC in 4 hours. By comparison, when the Arquad 16-29 cationic surfactant was replaced by an anionic surfactant, substantially all the OMC was extracted from the capsules in 4 hours.
• Example 1 was repeated except that 0.236g dimethyltin dineodecanoate catalyst was mixed into the OMC before it was emulsified, and only 46.6g water was used. Microcapsules of median diameter 329nm were produced with an encapsulation yield of 98%.
• Pigments can be added to the formulation of Example 6 or the formulation of
• Example 5 to make a foundation product with sun protection.
• HEC hydroxyethyl cellulose
• a leave-on conditioner with sun protection can be formed by simply diluting the encapsulated sunscreen suspension and adding preservative and perfume.
• Example 2 The process of Example 2 was repeated with the omission of the nonionic surfactant and the reduction of the amount of Arquad 16-29 cationic surfactant to 1.83g (Example 9) and 0.915g (Example 10).
• Example 2 The process of Example 2 was repeated with the omission of the cationic surfactant.
• Example 11 The process of Example 11 was repeated with the amount of Volpo L3 nonionic surfactant being halved to 0.82g. Examples 13 and 14
• Example 1 The process of Example 1 was repeated with the omission of the nonionic surfactant and the reduction of the amount of Arquad 16-29 cationic surfactant to 0.915g (Example 13) or to 0.366g (Example 14).
• test results of the microcapsule suspensions of Example 9, 10, 13 and 14 correspond to negligible leaching of the OMC from the microcapsules in a normal sunscreen vehicle.
• the test was continued to 120 hours at which time 21% of the OMC was extracted.
• Example 14 was repeated with an increase of the amount of TEOS added to

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• 2002
  • 2002-02-07 GB GBGB0202853.8A patent/GB0202853D0/en not_active Ceased
• 2003
  • 2003-02-03 WO PCT/EP2003/001071 patent/WO2003066209A1/en not_active Ceased
  • 2003-02-03 AT AT03708081T patent/ATE401952T1/de not_active IP Right Cessation
  • 2003-02-03 EP EP03708081A patent/EP1471995B1/en not_active Expired - Lifetime
  • 2003-02-03 AU AU2003212233A patent/AU2003212233A1/en not_active Abandoned
  • 2003-02-03 DE DE60322344T patent/DE60322344D1/de not_active Expired - Lifetime
  • 2003-02-03 JP JP2003565628A patent/JP4224403B2/ja not_active Expired - Lifetime

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