Colloid systems and wetting agents; subcombinations thereof; pro – Continuous liquid or supercritical phase: colloid systems;... – Aqueous continuous liquid phase and discontinuous phase...
Patent
1998-11-17
2000-10-31
Warden, Jill
Colloid systems and wetting agents; subcombinations thereof; pro
Continuous liquid or supercritical phase: colloid systems;...
Aqueous continuous liquid phase and discontinuous phase...
514938, 514943, 514937, C09K 300, B01F 1700, B01F 308, A01N 6100
Patent
active
06140375&
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to microemulsions containing fat-soluble ingredients and more specifically to microemulsions containing fat-soluble ingredients which are used in the field of pharmaceuticals, foods, cosmetics, etc., which have very small particle sizes, and which are stable in aqueous solutions.
BACKGROUND ART
Generally, the smaller the particle sizes of emulsions are, the higher their stability in aqueous solutions is. There are known several methods to obtain emulsions having small particle sizes by the addition of polyhydric alcohols to mixtures in which oily phases and nonionic surfactants have been dissolved followed by the emulsification thereof (Japanese Unexamined Patent Publication (Kokai) No. 62-250941, Japanese Examined Patent Publication (Kokoku) No. 63-61050, and Japanese Unexamined Patent Publication (Kokai) No. 63-107740). However, the particle sizes of the emulsions obtained by these methods are not small enough and hence it was difficult to secure stability in low-viscosity aqueous solutions. An alternative method for reducing particle sizes involves the use of a high-pressure homogenizer which exerts forcefully a physically great power to emulsions. But this requires extensive equipment, which significantly contributed to high cost of the method. Furthermore, although the emulsions obtained in this method are relatively stable in aqueous solutions having near-neutral pH or low concentrations of ionic substances, they have the problem of being unstable in aqueous solutions of pH 2.5-5.0 which are often used for medicinal beverages, refreshing beverages, etc., in aqueous solutions which contain inorganic salts, salts of organic acids and the like and which have high concentrations of ionic substances as high as 0.1-5% by weight, and thereby are easy to form creams, precipitates or the like.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide microemulsions containing fat-soluble ingredients which have very small particle sizes of 200 nm or smaller and which are stable for a long period of time in an aqueous solution, in particular even in an aqueous solution of pH 2.5-5.0 or an aqueous solution of high ionic concentrations wherein the concentrations of ionic substances are as high as 0.1-5% by weight.
After intensive research to attain the above objective, the inventors of the present invention have found that by combining specific nonionic surfactants at specific ratios, microemulsions containing fat-soluble ingredients with particle sizes as small as 10-150 nm can be obtained and that the microemulsions are very stable for a long period of time even in aqueous solutions of pH 2.5-5.0 or an aqueous solution of high ionic concentrations wherein the concentrations of ionic substances are as high as 0.1-5% by weight, and thus have completed the present invention.
Thus, the present invention is a microemulsion comprising (1) one or two selected from decaglycerol stearates having an HLB of 14 or greater and sucrose stearates having an HLB of 18 or greater, (2) one or two selected from decaglycerol myristates having an HLB of 13 or greater and decaglycerol laurates having an HLB of 14 or greater, (3) a fat-soluble ingredient, and (4) a water-soluble polyhydric alcohol, wherein the weight ratio of (1) and (2) is 1:0.5-1:6.
The present invention is characterized in that specific nonionic surfactants are combined at specific ratios, resulting thereby in microemulsions which have particle sizes of 200 nm or smaller and which are very stable for a long period of time even in an aqueous solution of pH 2.5-5.0 or an aqueous solution of high ionic concentrations wherein the concentrations of ionic substances are as high as 0.1-5% by weight
It is necessary to reduce the particle sizes to 200 nm or smaller in order to secure the stability of microemulsions in aqueous low-viscosity solutions. In particular, it is preferred that the particle sizes are 10-150 nm.
The HLB of decaglycerol stearates, nonionic surfactants for use in the present inv
REFERENCES:
patent: 5767180 (1998-06-01), Leube
Hasegawa Kazuo
Ito Yuji
Nagahama Tohru
Nakajima Toshiaki
Cole Monique T.
Taisho Pharmaceutical Co. Ltd.
Warden Jill
LandOfFree
Microemulsion does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Microemulsion, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Microemulsion will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2052333