MXPA00009403A - Carrier blends for dentifrices comprising ethoxlated polyhydric alcohols - Google Patents

Abstract

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.

Description

VEHICLE MIXTURES FOR DENTÍFRICOS COMPRISING ETOXILATED POLYHYDRIC ALCOHOLS 1. FIELD OF THE INVENTION The present invention relates to non-ionic, non-aqueous and stable copolymer mixtures useful as vehicles for personal care products. 2. BACKGROUND OF THE INVENTION Non-aqueous personal care compositions typically contain large amounts of a non-aqueous vehicle which provides a suitable matrix within which the active ingredients and other functional ingredients are added to form a personal care product which is easy to use It is known in the state of the art that the non-aqueous vehicle can be composed of a mixture of liquid components and solid components to provide a stable suspension during the formulation of said compositions for personal care. For example, the liquid components in a toothpaste formula can be low molecular weight polyethylene glycol, usually in the range between 200 and 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 polyethylene glycol with a higher molecular weight between 1,000 and 10,000. The solid component can also be a non-ionic surfactant, such as a three-block 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 active ingredients and other functional ingredients commonly found in personal care compositions, non-aqueous vehicles are required to 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, temperature changes, and cutting conditions. The stability of the non-aqueous vehicles and the personal care compositions made therefrom can therefore be translated into the ease of manufacturing the compositions and the stability of the compositions when used by the consumer. Additionally, personal care products, such as toothpastes, mouthwashes, cosmetics, gels and lotions, deodorants, and over-the-counter medications such as balms and ointments, are subject to freeze-thaw cycles during transportation and storage. Submitting personal care products to several freeze and thaw cycles can alter the product's rheology, creating a problem to dispense the product as the product becomes too hard or too soft or too viscous, and therefore difficult to use. Accordingly, non-aqueous vehicle compositions and the personal care compositions made therefrom should be stable under freezing and thawing conditions. Although other compositions comprising liquid and solid nonionic components are known, and which are stable under the above conditions, it is unknown in the state of the art to combine a liquid polyoxyethylene compound comprising an ethoxylated polyhydric alcohol with a non-polyoxyalkylene compound. solid ion as described below. 3. COMPENDIUM OF THE INVENTION. A non-aqueous and stable vehicle is provided for personal care compositions, which comprises: a) between 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) between 2-20% by weight of a solid nonionic polyoxyalkylene compound selected from: i) surfactants in three solid nonionic blocks comprising an internal block of polyoxypropylene and two external blocks of polyoxyethylene, wherein the nominal average molecular weight of the polyoxypropylene block ranges from 2000 to 2900 approximately, and the polyoxyethylene content ranges from 70 to 80% by weight, based on the total molecular weight of the surfactant in three blocks; ii) solid polyethylene oxide with a nominal average molecular weight greater than about 2000; and iii) mixtures thereof.

Tooth compositions comprising the non-aqueous and stable carrier are also provided. 4. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT The liquid polyoxyalkylene compounds of the present invention can be prepared by means well known in the state of 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 optionally be neutralized with neutralizing acids well known in the art. See, for example, Block & Graft Copolymerization, Volume 2, Chapter 1, edited by R.J. Ceresa (Wiley, 1981), incorporated herein by reference. The polyhydric alcohols useful in making the liquid polyoxyalkylene compounds of the present invention are generally those having between 3 and 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 between 3 and 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 liquid, particularly at room temperature of about 20-25 ° C. It is preferable that they are liquids in a wider temperature range such that flexibility can be achieved 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 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 that it will continue to be a liquid at higher temperatures, that is, 60 ° C or more. By lowering the temperature, the ethoxylated polyhydric alcohols of the invention will generally become more viscous until a temperature is reached where the ethoxylated polyhydric alcohol will no longer pour out. The requirement to be liquid at a certain temperature will be met if the pouring temperature of the composition is below that temperature. Accordingly, the liquid polyoxyalkylene compounds of the present invention comprising ethoxylated polyhydric alcohols will generally exhibit good pouring properties in the temperature range between 0 ° C to 60 ° C and more. An example of an ethoxylated polyhydric alcohol is ethoxylated glycerol. In general, the level of ethoxylation must be such that the ethoxylated glycerol is a liquid. If desired, minor amounts of propylene oxide can be incorporated into the ethoxylated glycerol to make an ethoxylated liquid that would otherwise be a solid. The ethoxylated glycerol can also be made with only ethylene oxide. It is preferred that the level of ethoxylation in the ethoxylated glycerol does not exceed about 60 units of ethylene oxide per glycerol molecule. Preferably, the level of ethoxylation in the ethoxylated glycerol will be less than about 20 ethylene oxide units per glycerol molecule, typically between about 5 and about 20 ethylene oxide units per glycerol molecule. A particularly preferred ethoxylated glycerol has an ethoxylation level of about 12 ethylene oxide units per glycerol molecule. Another preferred ethoxylated glycerol has an ethoxylation level of about 10 ethylene oxide units per glycerol molecule. The carrier compositions generally comprise between about 80% and 98% by weight of the liquid polyoxyalkylene compounds described above, preferably between about 85% and 95%, and more preferably between about 88% and about 92% by weight. The stable non-aqueous vehicles of the present invention also comprise a solid nonionic polyoxyalkylene compound. This nonionic polyoxyalkylene compound may be either a solid non-ionic three-block surfactant, a solid polyethylene oxide compound, or mixtures thereof.

The surfactants in three solid nonionic blocks include those that have an internal polyoxypropylene block and two outer blocks of polyoxyethylene. The surfactants in three preferred solid nonionic blocks have a polyoxypropylene block with a nominal average molecular weight between about 2000 and about 2900. Additionally, the surfactants in three preferred blocks have a polyoxyethylene content between about 70-80%, based on the total molecular weight of the surfactant in three blocks. Surfactants in three preferred blocks, having a polyoxypropylene block with a nominal average molecular weight between 2000 and 2900 approximately and a polyoxyethylene content between about 70 and 80% based on the total molecular weight of the surfactant in three blocks, include PLURONIC® F-98 and PLURONIC® F-88, commercially available from the BASF Corporation. The solid polyethylene oxides are also useful as the solid nonionic polyoxyalkylene compounds of the present invention. These include polyethylene oxides and polyethylene glycols with a nominal average molecular weight above about 2000. Preferred polyethylene oxides are those with a nominal average molecular weight greater than or equal to about 4000.

Examples include PEG 4000, PEG 4500, and PEG 6000. Such solid polyethylene oxide compounds are commercially available from a variety of sources. Examples include PLURACOL® E-4000 and PLURACOL® E-6000, both available from BASF Corporation. The solid nonionic polyoxyalkylene compound is generally present at a level between about 2% and 20% by weight, based on the total weight of the non-aqueous vehicle composition. Preferably, it will be present at a level between about 5% and about 15%, and more preferably between about 8% and about 12% by weight. Non-aqueous and stable vehicle mixtures useful for personal care compositions are prepared by mixing the liquid polyoxyalkylene compound with the solid nonionic polyoxyalkylene compound. Preferably, 80-90% by weight of the liquid polyoxyalkylene compound is mixed with 2-20% by weight of the solid nonionic polyoxyalkylene compound. More preferably, 85-95% by weight of the liquid polyoxyalkylene compound is mixed with 5-15% by weight of the solid nonionic polyoxyalkylene compound. Most preferably, 88-92% by weight of the liquid polyoxyalkylene compound is mixed with 8-12% by weight of the solid nonionic polyoxyalkylene compound.

The resulting composition is then heated to about 70 ° C or until a single phase clear composition is obtained. The composition is then cooled with stirring in a Lightin® mixer set at 100 rpm until the temperature of the composition is ambient (approximately 35 ° C). The composition is then allowed to equilibrate for 24 hours at room temperature (approximately 25 ° C). At the end of the equilibrium period, the composition is opaque in its appearance and has the consistency of an ointment paste. The viscosity of the composition can be determined using a Brookfield Cone / Plate rotary viscometer. As demonstrated in Table 1, the liquid polyoxyalkylene compounds of the invention are good solvents for flavor oils, while glycerol, commonly used as a component of non-aqueous vehicle compositions, is not. In Table 1, 0.2% solutions of the flavor oils in the ethoxylated polyhydric alcohols (exemplified by a 12 mol glycerol ethoxylate) gave clear solutions while the glycerol solutions were hazy. This property leads to advantages in the formulation of dentifrice compositions of the invention. For example, a flavor oil may be added to the non-aqueous vehicle mixture of the invention to achieve good incorporation of the flavor oil in the dentifrice composition. Suitable flavoring oils include, but are not limited to gualteria oil (methyl salicylate), peppermint oil, peppermint oil, clove oil, menthol, anethole, eucalyptol, cassia, 1-mentyl acetate, sage, eugenol, parsley oil, oxanone, alpha-irisone, marjoram, lemon, orange, propenyl guaetol, cinnamon, vanillin, ethyl vanillin, heliotropin, 4-cis-heptenal, diacetyl, methyl-para-tert-butyl phenyl acetate, and mixtures thereof. A flavoring system is generally used in the compositions at levels between 0.001% to approximately 5% by weight of the composition.

TABLE 1 0.2% flavor oil solutions in ethoxylated polyhydric alcohol 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 between 10 and 20). It is noted that while glycerol has a sweet taste, 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 offer a benefit to formulators who do not prefer the sweet taste of glycerin. Formulations that use glycerin in such compositions usually have to rely on expensive flavoring agents to mask the sweet taste given by glycerin. Since the glycerol ethoxylates are basically unsatisfactory, the use of masking agents in dentifrice compositions can be minimized. Alternatively, the sweetening agents may be added to the dentifrice compositions of the present invention to compensate for the lack of candy. These include saccharin, dextrose, sucrose, lactose, maltose, levulose, aspartame, sodium cyclamate, D-tryptophan, dihydrochalcones, acesulfame, and mixtures thereof. TABLE 2 Preparation of Personal Care Compositions Containing the Mixtures of Non-Aqueous and Stable Vehicles of the Present Invention The personal care compositions preferably comprise between 10 and 90% by weight of the stable non-aqueous vehicle mixtures of the present invention, more preferably between 25-85%, most preferably between 40-80% by weight. Personal care formulations comprising these stable non-aqueous vehicle mixtures may additionally comprise other ingredients such as surfactants selected from anionic surfactants, such as sodium lauryl sulfate, sodium alkyl glyceryl ether sulfonate, and alkylbenzene sulfonates. Additionally, small amounts of cationic surfactants, having a quaternary nitrogen, which show compatibility with the nonionic vehicle mixtures of this invention, may also be used. Various other materials can also be used in the formulation of personal care products. For example, in a toothpaste, dental abrasives consisting of freely divided silica, or calcium carbonate, calcium pyrophosphate, and hydrated alumina are added for polishing performance purposes. Additionally, thickening agents such as xanthan gum, gum arabic, and hydroxyethylcellulose can also be used to provide a sufficient thickening consistency to the formulation. Likewise, flavoring agents such as peppermint, peppermint oils or preservatives, opacifying agents, buffer salts, sweeteners, antibacterial agents or anticalculus agents, anti-inflammatory agents, and anti-caries agents such as fluoride salts may also be included in small amounts. Polymeric agents which accelerate the transport of active materials can also be included. Similarly, emollients such as glycerin, mineral oil and petrolatum can be added in cosmetic creams. Personal care products are formulated according to methods known to those skilled in the art. Representative formulations of personal care products are disclosed in: Cosmetics, Science and Technology, 2nd Edition, Vol. 1, edited by M.S. Balsam, et al., And A Formulary of Cosmetic Preparations, Michael and Irene Ash, Chemical Publishing, NY, NY, both incorporated herein by reference. The following non-limiting Examples serve to illustrate the application of the present invention. All percentages are by weight of the total composition unless otherwise indicated.

Tooth composition: 10 to 55% abrasive, selected from the group including, but not limited to, anhydrous dicalcium phosphate, calcium carbonate, calcium pyrophosphate. 0.2 to 0.8% stannous fluoride, sodium monofluorophosphate 2 to 10% binders, including, but not limited to, karaya gum, USP tragacanth, sodium alginate; Irish moss and methylcellulose. 2 to 8% surfactants, including, but not limited to, lauryl sulfate and sodium, sodium sarcosinate-N-lauryl; dioctyl sodium sulfosuccinate. 10 to 50% humectants, including, but not limited to, glycerol; propylene glycol; sorbitol; polyethylene glycol. 25 to 85% non-aqueous vehicle mixture of the present invention 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: i) surfactants in three solid nonionic blocks comprising an internal block of polyoxypropylene and two outer blocks of polyoxyethylene, wherein the nominal average molecular weight of the polyoxypropylene block ranges from about 2000 to about 2900, and the polyoxyethylene content ranges from 70 to 80% by weight, based on the total molecular weight of the surfactant in three blocks; ii) solid polyethylene oxide with a nominal average molecular weight greater than about 2000; and iii) mixtures thereof.

EXAMPLES The Examples show the stability of various mixtures of an ethoxylated polyhydric alcohol (exemplified by glycerol plus 12 moles of ethylene oxide OE) with a series of solid nonionic polyoxyalkylene compounds. The mixtures were prepared according to the method described above. Each Example contained 90% by weight of ethoxylated glycerol with an ethoxylation level of about 12, and 10% by weight of the listed solid polyoxyalkylene compounds. The results are given for stability tests at room temperature, high temperature stability, and stability against freezing and thawing. Room temperature stability refers to a test where the compositions are maintained at 25 ° C for a period of two months. After two months, the compositions are visually inspected to observe some phase separation or other changes. A stable composition at the end of the two-month period is reported if the composition is a homogeneous single-phase system. An unstable composition is reported if the composition is divided into two phases. For the freeze / thaw test, the compositions of the Examples were subjected to three cycles of freezing and thawing. After the tests, the samples are examined visually to observe stability such as the stability test at room temperature mentioned above. The third test, for stability at high temperature, involves keeping the compositions of the Examples in an oven at 50 ° C for a period of two months. Then, the stability was determined such as the stability test at room temperature and freezing and thawing mentioned above. The preferred solid nonionic compounds exhibit stability in the room temperature stability test, the freeze and thaw test and the high temperature stability test. It is observed in Examples 3 and 4 that PLURONIC® F-98 and PLURONIC® F-88 show stability in all three tests. Examples 7-11 show a series of polyethylene oxides. It is observed from Examples 10 and 11 that solid ethylene oxides with molecular weight greater than about 2000 demonstrate stability in the high temperature stability test. Polyethylene oxides with molecular weights of 2000 or less, exemplified in Examples 7-9, are unstable in the high temperature stability test.

Claims (23)

1. CLAIMS: 1. A non-aqueous and stable vehicle 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 groups hydroxyl, and ethylene oxide; and b) 2-20% by weight of a solid nonionic polyoxyalkylene compound selected from: i) surfactants in three solid nonionic blocks comprising an internal block of polyoxypropylene and two outer blocks of polyoxyethylene, wherein the nominal average molecular weight of the polyoxypropylene block ranges from about 2000 to about 2900, and the polyoxyethylene content ranges from 70 to 80% by weight, based on the total molecular weight of the surfactant in three blocks; ii) solid polyethylene oxide with a nominal average molecular weight greater than about 2000; and iii) mixtures thereof.
2. 2. A non-aqueous and stable vehicle according to claim 1, wherein said solid nonionic polyoxyalkylene compound comprises polyethylene oxide with a nominal average molecular weight greater than or equal to about 4000.
3. 3. A non-aqueous and stable vehicle according to claim 1, wherein said solid nonionic polyoxyalkylene compound comprises surfactants in three solid non-ionic blocks.
4. 4. A non-aqueous and stable vehicle according to claim 1, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level of less than about 60.
5. 5. A non-aqueous and stable vehicle according to claim 1, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level of less than about 20.
6. 6. A non-aqueous and stable vehicle according to claim 1, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level between about 5 and about 20.
7. 7. A non-aqueous and stable vehicle according to claim 1, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level of about 12.
8. 8. A non-aqueous and stable vehicle according to claim 1, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level of about 10.
9. 9. A non-aqueous and stable vehicle for personal care compositions, which comprises: a) 80-98% by weight of a liquid polyoxyalkylene compound comprising an ethoxylated glycerol; b) 2-20% by weight of surfactants in three solid non-ionic blocks comprising an internal block of polyoxypropylene and two external polyoxyethylene blocks, where the nominal average molecular weight of the polyoxypropylene block ranges from 2000 to 2900, and the content of polyoxyethylene ranges from 70 to 80% by weight, based on the total molecular weight of the surfactant in three blocks.
10. 10. A non-aqueous and stable vehicle according to claim 9, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level up to a value of about 60.
11. 11. A non-aqueous and stable vehicle according to claim 9, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level up to a value of about 20.
12. 12. A non-aqueous and stable vehicle according to claim 9, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level between about 5 and about 20.
13. 13. A non-aqueous and stable vehicle according to claim 9, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level of about 12.
14. 14. A non-aqueous and stable vehicle according to claim 9, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level of about 10.
15. 15. A non-aqueous and stable vehicle for personal care compositions, which comprises: a) 80-98% by weight of a liquid polyoxyalkylene compound comprising an ethoxylated glycerol; and b) 2-20% by weight of a solid polyethylene oxide with a nominal average molecular weight greater than or equal to about 4000.
16. 16. A non-aqueous and stable vehicle according to claim 15, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level up to a value of about 60.
17. 17. A non-aqueous and stable vehicle according to claim 15, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level up to a value of about 20.
18. 18. A non-aqueous and stable vehicle according to claim 15, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level between about 5 and about 20.
19. 19. A non-aqueous and stable vehicle according to claim 15, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level of about 12.
20. 20. A non-aqueous and stable vehicle according to claim 15, wherein said liquid polyoxyalkylene compound comprises ethoxylated glycerol having an ethoxylation level of about 10.
21. 21. An anhydrous dentifrice composition comprising between 25-85% by weight of a non-aqueous and stable vehicle according to claim 1.
22. 22. An anhydrous dentifrice composition comprising between 25-85% by weight of a non-aqueous and stable vehicle according to claim 9.
23. 23. An anhydrous dentifrice composition comprising between 25-85% by weight of a non-aqueous and stable vehicle according to claim 15.