Drug – bio-affecting and body treating compositions – Dentifrices
Reexamination Certificate
1999-12-27
2002-01-01
Rose, Shep K. (Department: 1614)
Drug, bio-affecting and body treating compositions
Dentifrices
Reexamination Certificate
active
06335001
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to stable non-aqueous nonionic copolymer blends useful as carriers for personal care products.
BACKGROUND OF THE INVENTION
Non aqueous personal care compositions typically contain major amounts of a non-aqueous carrier which provides a suitable matrix into which the active ingredients, and other functional ingredients are added to form a personal care product that is easy to use. It is known in the art that the non-aqueous carrier can be composed of a blend of liquid component(s) and solid component(s) to provide a stable suspension during the formulation of said personal care compositions. For example, the liquid components in a toothpaste formula can be polyethylene glycol of low molecular weight, typically in the range of 200-400. Other liquid components, such as glycerol, or polypropylene glycol can also be used. The solid component, which is usually added to modify the rheology of the composition, can be a higher molecular weight polyethylene glycol of molecular weights between 1,000-10,000. The solid component can also be a nonionic surfactant, such as a triblock copolymer of ethylene oxide/propylene oxide/ethylene oxide (EO/PO/EO). Said solid nonionic surfactant typically consists of 80% ethylene oxide and has a molecular weight usually greater than about 10,000.
In addition to compatibility with the active ingredients and other functional ingredients commonly found in personal care compositions, it is required that the non-aqueous carriers be stable. That is, the compositions should show no phase separation and maintain adequate viscosity when subjected to a variety of conditions, including extreme temperatures, changes of temperature, and shear conditions. Stability of the non-aqueous carriers and the personal care compositions made from them thus can translate to the ease of manufacture of the compositions and to the stability of the compositions when in use by the consumer.
Further, personal care products, such as toothpastes, mouthwashes, cosmetic creams, gels and lotions, antiperspirants, deodorants, and over-the-counter medicaments such as salves and ointments, are subject to freeze-thaw cycles during shipment and storage. Subjecting personal care products to several freeze thaw cycles can alter the an rheology of the product, creating a product dispensing problem when the product becomes too hard or too soft or too viscous, and hence, difficult to use. Thus, non-aqueous carrier compositions and the personal care compositions made from them should be stable to freeze-thaw conditions.
Although other compositions comprising liquid and solid nonionic components are known, which are stable under the above conditions, it is unknown in the art to combine a liquid polyoxyethylene compound comprising an ethoxylated polyhydric alcohol with a solid nonionic polyoxyalkylene compound such as described below.
SUMMARY OF THE INVENTION
There is provided a stable non-aqueous carrier for personal care compositions comprising:
a) 80-98% by weight of a liquid polyoxyalkylene compound comprising a reaction product of an alcohol having 3 to 6 hydroxyl groups and ethylene oxide; and
b) 2-20% by weight of a solid nonionic polyoxyalkylene compound selected from the group consisting of:
i) solid nonionic triblock surfactants comprising an inner polyoxypropylene block and two outer polyoxyethylene blocks, wherein the number average molecular weight of the polyoxypropylene block is from about 2000 to about 2900, and the polyoxyethylene content is about 70 to 80 weight percent, based on the total molecular weight of the triblock surfactant;
ii) solid polyethylene oxide having a number average molecular weight of greater than about 2000; and
iii) mixtures thereof.
There are also provided dentifrice compositions comprising the stable non-aqueous carrier.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Liquid polyoxyalkylene compounds of the present invention can be prepared by means well known in the art by reacting a polyhydric alcohol with appropriate amounts of ethylene oxide in the presence of an alkaline catalyst. The resulting polyether, which may also be called an ethoxylated polyhydric alcohol, may be optionally neutralized with neutralization acids well known in the art. See, for example,
Block & Graft Copolymerization,
Volume 2, Chapter 1, edited by R. J. Ceresa (Wiley, 1981), hereby incorporated by reference.
Polyhydric alcohols useful for making the liquid polyoxyalkylene compounds of the present invention are generally those that have from 3 to 6 hydroxyl groups. Examples of polyhydric alcohols include, but are not limited to, glycerol, trimethylolpropane, 1,2,6-hexanetriol, ditrimethylolpropane, pentaerythritol, glucose, and sorbitol. The liquid polyoxyalkylene compound thus comprises a reaction product of an alcohol having 3 to 6 hydroxyl groups and an appropriate amount of ethylene oxide.
The ethoxylated polyhydric alcohols are characterized by a degree of ethoxylation such that they are liquids, particularly at room temperature or at about 20°-25° C. It is preferable that they be liquid over a wider range of temperature so that flexibility can be gained during their preparation, handling, storage and use by the consumer. It is most preferred that the ethoxylated polyhydric alcohols be liquid down to a temperature of about 0° C. and up to a temperature of about 60° C. Generally, if the ethoxylated polyhydric alcohol is a liquid at room temperature, there will be no problem with it continuing to be a liquid at higher temperatures, i.e., at 60° C. and above. As the temperature is lowered, the ethoxylated polyhydric alcohols of the invention generally will become more viscous until a temperature is reached below which the ethoxylated polyhydric alcohol will no longer pour. The requirement of being liquid at a certain temperature is met if the pour point of the composition is below that temperature. Thus, the liquid polyoxyalkylene compounds of the present invention comprising ethoxylated polyhydric alcohols will generally exhibit good pour properties over the temperature range of about 0° C. up to 60° C. and above.
An example of an ethoxylated polyhydric alcohol is ethoxylated glycerol. In general, the level of ethoxylation should be such that the ethoxylated glycerol is a liquid. If desired, minor amounts of propylene oxide may be incorporated into the ethoxylated glycerol to make an otherwise solid ethoxylate liquid. The ethoxylated glycerol may also be made with only ethylene oxide. It is preferred that the level of ethoxylation on the ethoxylated glycerol not exceed about 60 units of ethylene oxide per glycerol molecule. Preferably, the level of ethoxylation on the ethoxylated glycerol will be less than about 20 units of ethylene oxide per glycerol molecule, typically from about 5 to about 20 units of ethylene oxide per glycerol molecule. A particularly preferred ethoxylated glycerol has a level of ethoxylation of about 12 units of ethylene oxide per glycerol molecule. Another preferred ethoxylated glycerol has a level of ethoxylation of about 10 units of ethylene oxide per glycerol molecule.
The carrier compositions generally comprise from about 80% to about 98% by weight of the liquid polyoxyalkylene compounds described above, preferably from about 85% to about 95%, and most preferably from about 88% to about 92% by weight.
The stable non-aqueous carriers of the present invention also comprise a solid nonionic polyoxyalkylene compound. This nonionic polyoxyalkylene compound can be either a solid nonionic triblock surfactant, a solid polyethylene oxide compound, or mixtures thereof.
Solid nonionic triblock surfactants include those having an inner polyoxypropylene block and two outer polyoxyethylene blocks. Preferred solid nonionic triblock surfactants have a polyoxypropylene block with a number average molecular weight of from about 2000 to about 2900. Furthermore, preferred triblock surfactants have a polyoxyethylene content of about 70-80%, based on the total molecular weight of the triblock surfactant.
Preferred trib
Guiney Kathleen M.
Palkrishnan Sridhar
Banchik David T.
BASF Corporation
Rose Shep K.
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