Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Particulate form
Patent
1996-09-25
1999-03-02
Brouillette, D. Gabrielle
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Particulate form
424401, 424 761, 424 701, 424484, 424486, A61K 914
Patent
active
058767550
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/EA94/00467, filed Feb. 17, 1994, WO94/19449, Sep. 1, 1994.
FIELD OF THE INVENTION
This invention relates to a composition comprising a substance encapsulated within a water-sensitive matrix, which is water-soluble but stable at high relative humidity, and a method of making such a composition.
BACKGROUND OF THE INVENTION
Encapsulated products have been described in which perfume or other poorly water-soluble oil is protected from hostile ingredients by being contained in solid products. Such products are formed by incorporating perfume or other poorly water-soluble oil in a water sensitive matrix which may be a starch or polymer or other material. These encapsulates can also be used to control the release of perfume until the product encounters water; alternatively the perfume may be slowly released by diffusion. The encapsulates may be added to a variety of consumer products, including laundry powder, soap, machinedishwash powder or any other substantially dry solid consumer product. During manufacture or storage these products may encounter high humidity which will cause the breakdown of the encapsulate and the premature release of the perfume.
High humidity conditions are frequently present in a laundry powder factory, particularly those which spray-dry the base powder, but also in non-tower production routes in humid climates. It is not unlikely that the conditions inside a factory could be 33.degree. C./90% relative humidity. Under these conditions a starch encapsulated perfume would be quickly released and the encapsulate powder would become a sticky mass, eventually deliquescing. Thus, it is not normally possible to use starch or similar water soluble encapsulation materials to protect vulnerable perfume ingredients from the hostile materials present in the laundry powder base.
Similarly, very humid conditions are frequently found in soap manufacturing, and in addition soaps may retain a degree of free water within their structure. Thus water sensitive encapsulates are not normally suitable for use in these products.
BRIEF DESCRIPTION OF THE PRIOR ART LITERATURE
Starch encapsulated oils have been prepared and used in a variety of products. Preparation techniques and a range of encapsulation media are described in U.S. Pat. No. 3,455,838 (NSCC). Starch encapsulates have been used in underarm products to provide controlled release of fragrance (EP 480520, Quest). Starch encapsulation is disclosed in EP 070 719 (Unilever) to provide protection for perfume against the action of various components of the detergent.
Silica loaded with perfume oil has also been described extensively. Zimmermann (GB 1 306 924) found that perfume could be loaded onto silica, up to 2.5 times its own weight, and this remained a free flowing powder. The perfume-loaded powder was added to laundry powder to improve the homogeneity of the perfume addition. The silica used was a finely divided silica gel with a particle size less than 10 .mu.m.
A similar material was described by Vysoka Skola Chemicko-Technologicka (GB 2 066 839); a porous hydrated silicon dioxide was loaded to 50% with perfume and added to a laundry powder. A substantial reduction of perfume volatility was observed and chemical changes were avoided during storage of the product.
It was found by Colgate Palmolive (GB 2 141 730) that a beneficial effect could be obtained on laundered fabric if perfume were incorporated into the laundry powder via a carrier particle. The carrier particle consisted of zeolite or clay with perfume absorbed or adsorbed onto it at up to 25% of perfume. An additional coating of anionic, nonionic or cationic surfactant was found to improve the deposition of the particle onto the fabric (GB 2 140 820).
Perfumed particles which release perfume when wetted were described by Proctor and Gamble (EP 332 259). In one embodiment, the particles consisted of perfume adsorbed onto silica particles. The silica was preferably fumed silica with a particle size between 0.007 and 2.5 .mu.m and a surface area of 20
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patent: 5188753 (1993-02-01), Schmidt
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Birch Richard Arthur
Ness Jeremy Nicholas
Perring Keith Douglas
Brouillette D. Gabrielle
Quest International BV
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