Drug – bio-affecting and body treating compositions – Dentifrices
Reexamination Certificate
1999-12-27
2002-01-29
Rose, Shep K. (Department: 1614)
Drug, bio-affecting and body treating compositions
Dentifrices
C424S053000
Reexamination Certificate
active
06342206
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to ethoxylates of polyhydric alcohols, and their use in dentifrice gels or personal care compositions.
BACKGROUND OF THE INVENTION
The use of ethoxylated polyhydric alcohols, such as glycerol and sorbitol, is known in skin care and pharmaceutical compositions. The use of ethoxylated glycerol in an oral composition at a use level of 0.15%, as part of a sodium lauryl sulfate
onionic surfactant blend, has also been reported.
The use of high molecular ethylene oxide/propylene oxide triblock surfactants in aqueous gel compositions is well known. See, for example, the discussion in U.S. Pat. No. 5,908,612. With such triblock surfactants, aqueous gel compositions can be readily formed which have desirable viscosity properties over an appropriate temperature range.
It is also known to make aqueous gel compositions from such triblock surfactants in combination with glycerol.
A peroxide gel dentifrice comprising glycerol, a triblock surfactant, and a peroxide material has been reported, as has a mouthwash containing a nonionic surfactant which can be a polyoxyethylene polyoxypropylene block surfactant, a humectant which can be glycerol, and an antibacterial agent.
It is known to use gelling agents with humectants such as glycerol or sorbitol in order to make aqueous toothpastes. Such gelling agents include crosslinked polyacrylic thickeners, cellulose derivatives, and hydrated silicas.
The use of ethoxylated polyhydric alcohols to prepare aqueous dentifrice gels is unknown. Nor have the ethoxylated polyhydric alcohols been used as humectants or as a carrier in toothpaste compositions.
Applicants have surprisingly found that certain ethoxylated polyhydric alcohols having an effective amount of ethoxylation are useful in preparing aqueous dentifrice compositions. Furthermore, the ethoxylated polyhydric alcohols exhibit many advantages over the materials used in the prior art.
Aqueous gel compositions made with polyoxyethylene/polyoxypropylene/polyoxyethylene triblock surfactants are thermally reversible, a property which formulators have taken advantage of to facilitate the processing of such gels. Furthermore, gels formulated with the triblock surfactants show exceptional tolerance toward electrolytes and are stable over wide ranges of pH and temperature.
However, a common limitation with dentifrice gels formulated with copolymers of ethylene oxide and propylene oxide is that due to their thermally reversible gelation properties, the gels can instantly liquefy to a pourable liquid as soon as the temperature falls below the sol-gel transition temperature. Such an event can possibly lead to leakage of fluid from the package. It has been surprisingly discovered that dentifrice compositions containing suitable amounts of ethoxylated polyhydric alcohols protect the dentifrice gel composition from sudden loss of viscosity at lower temperatures.
Another advantage of the ethoxylated polyhydric alcohols of the present invention is that they are good solvents for a variety of flavor oils.
SUMMARY OF THE INVENTION
There is provided according to the present invention an aqueous gel composition, comprising
a) an ethoxylated polyhydric alcohol which comprises a reaction product of an alcohol having 3 to 6 hydroxy groups with ethylene oxide; and
b) a gelling agent selected from the group consisting of a polyoxyethylene/polyoxypropylene/polyoxyethylene triblock surfactant having a molecular weight of from 4,000 to 16,000, and wherein the weight of the polyoxyethylene blocks is from 55% to 90% of the weight of the triblock surfactant; a crosslinked polyacrylic thickener; cellulose derivatives; hydrated silicas; and mixtures thereof.
In one embodiment, the invention is an aqueous gel composition comprising an ethoxylated polyhydric alcohol, a gelling agent and water. The ethoxylated polyhydric alcohol comprises the reaction product of an alcohol having 3 to 6 hydroxyl groups with ethylene oxide, preferably such that up to 5 mole equivalents of ethylene oxide are reacted per mole equivalent of hydroxyl group. The gelling agent is selected from the group consisting of polyoxyethylene/polyoxypropylene/ polyoxyethylene triblock surfactants, crosslinked polyacrylic thickeners, cellulose derivatives, and hydrated silicas. When the gelling agent is the triblock surfactants, the ethoxylated polyhydric alcohol comprises the reaction product of the polyhydric alcohol and up to 5 mole equivalents of ethylene oxide per mole equivalent of hydroxyl group in the alcohol.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
The ethoxylated polyhydric alcohols 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 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 ethoxylated polyhydric alcohols 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 ethoxylated polyhydric alcohol is thus the reaction product of an alcohol having 3 to 6 hydroxyl groups and an appropriate amount of ethylene oxide.
As shown in Table 1, the ethoxylated polyhydric alcohols of the invention are good solvents for flavoring oils. In Table 1, it can be seen that 0.2% solutions of the flavoring oils in the polyhydric alcohols (exemplified by a glycerol 12 mole ethoxylate) give clear solutions while the solutions in glycerol are hazy.
TABLE 1
Solutions of 0.2% flavor oils in ethoxylated polyhydric alcohol
EUCA-
METHYL
LYP-
CAM-
SALICY-
MEN-
PRODUCT
TUS OIL
PHOR
LATE
THOL
THYMOL
GLYCEROL
Hazy
Hazy
Hazy
Hazy
Hazy
GLYCEROL +
Clear
Clear
Clear
Clear
Clear
12 eo
Table 2 presents a comparison of the physical properties of glycerin and three different ethoxylated polyhydric alcohols (represented by ethoxylated glycerol with levels of ethoxylation from 10 to 20). It is seen that whereas glycerol has a sweet taste, the glycerol ethoxylates are essentially tasteless. That is, the ethoxylated polyhydric alcohols of the present invention do not have the sweet taste of glycerin. This may provide a benefit to formulators who do not prefer the sweet taste of glycerin. Formulators using glycerin in such compositions often have to rely upon expensive flavoring agents to mask the sweet taste imparted by glycerin. Since glycerol ethoxylates are essentially tasteless, the use of masking agents in dentifrice compositions can be minimized. Alternatively, the lack of sweetness may be compensated for, if desired, by adding sweeteners to compositions of the invention containing ethoxylated polyhydric alcohols.
TABLE 2
PRODUCT
TASTE
POUR POINT
GLYCEROL
SWEET
17° C.
GLYCEROL-10 MOLE EO
TASTELESS
−39° C.
GLYCEROL-12 MOLE EO
TASTELESS
not determined.
GLYCEROL-20 MOLE EO
TASTELESS
−5° C.
The ethoxylated polyhydric alcohols of the current invention find utility in aqueous based dentifrice compositions in two ways, which will be described below.
The first is as a component of an aqueous gel composition comprising a particular class of polyoxyethylene/polyoxypropylene/polyoxyethylene triblock surfactant. The ethoxylated polyhydric alcohols of the invention can be used to replace partially or completely the known compounds such as glycerol which have been used in such formulations up to now. For this application, the level of ethoxylation on the ethoxylated polyhydric alcohol can have an important impact on the gelling properties.
The second is as a humectant or carrier in aqueous based toothpaste compositions comprising one or more known thickening agents such as crosslinked polyacrylic thickeners, cellulose derivatives, and h
Dailey James S.
Gopalkrishnan Sridhar
Guiney Kathleen M.
Holland Richard J.
Banchik, Esq. David T.
Rose Shep K.
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