WO1996001616A1

WO1996001616A1 - Polyglycerol ester composition and method for its production

Info

Publication number: WO1996001616A1
Application number: PCT/US1995/009387
Authority: WO
Inventors: Andre Joseph Eydt
Original assignee: Lonza Inc.
Priority date: 1994-07-11
Filing date: 1995-07-10
Publication date: 1996-01-25
Also published as: IL114550A0; AU3146195A

Abstract

A flowable liquid composition comprising about 1 to 5 wt.% of a polyglycerol fatty acid ester, about 1 to 20 wt.% by weight of water and about 75 to 95 wt.% of a polyol; a method for producing such compositions; and personal care formulations contain such compositions. The method includes dissolving a polyglycerol ester at a temperature from about 60 °C to 80 °C in solution comprising a polyol and water, the amount of water being sufficient to prevent gelation of the composition at room temperature.

Description

POLYGLYCEROL ESTER COMPOSITION AND METHOD FOR ITS PRODUCTION

BACKGROUND OF THE INVENTION

This invention relates to polyglycerol ester additives for a wide variety of formulations, such as personal care products, particularly dentifrices, containing such additives as surfactants and/or viscosity modifiers.

Conventional personal care formulations, such as dentifrices, generally contain surfactants to increase their cleaning action and provide the foaming properties expected by the user. Polyglycerol esters have been used for this purpose, as described in U.S. Patent 4,865,839 to Saso.

A dentifrice should be formulated to conveniently extrude from a tube as a ribbon, break sharply, and retain integrity for a reasonable period of time on a toothbrush. To provide the proper texture, dentifrices containing polyglycerol esters require additional thickeners, such as sodium carboxymethyl cellulose, carrageenan or polyethylene glycol, to control formulation flow properties. (See, for example, Jpn. Kokai JP 62 45,513 (1987)). In recent years, the toxicity and environmental effects of some of these compounds, particularly the ethoxylated compounds commonly used as thickeners, have been questioned. If high levels of polyglycerol esters could be incorporated into the dentifrice, it would be possible to limit or eliminate the need for the potentially harmful thickening agents. However, polyglycerol esters are insoluble in water at room temperature, and the highly viscous solutions which result when the compound is mixed with water cannot readily be added to the dentifrice in a room temperature manufacturing process. The polyglycerol esters may be added to the dentifrice formulation using a high temperature processing step, but such a procedure is undesirable because it is not part of the conventional manufacturing processes.

Thus, while polyglycerol esters provide many potential benefits in personal care formulations, the use of these compounds requires incorporation of additional thickening ingredients in the formulation, or a difficult to implement high temperature processing step.

SUMMARY OF THE INVENTION

In accordance with the invention, a polyglycerol ester composition has now been discovered which may be incorporated into personal care products at room temperature in a conventional manufacturing process. The resulting personal care products do not require additional thickening agents to control their viscosity.

The present invention also includes a method of preparing a polyglycerol ester composition for subsequent introduction at room temperature into a personal care formulation. In the method of the invention, the polyglycerol ester is first added to a mixture of a polyol and water at a temperature above room temperature, and allowed to cool to room temperature to produce a polyglycerol ester additive composition. The resulting composition is flowable at room temperature, and may easily be incorporated at room temperature into dentifrices and other personal care products.

The polyglycerol ester composition of the invention makes it possible to prepare personal care products at room temperature which are thickened with polyglycerol esters, and are substantially free of other viscosity modifiers, without altering the conventional manufacturing process. The resulting personal care products are an improvement over prior art in that a well performing product can be more simply and economically manufactured with a smaller number of ingredients. The polyglycerol ester composition of the invention is formulated with an amount of water sufficient to prevent gelation of the composition at room temperature, i.e., with a viscosity of less than 100K cps, but not so great as to permit the spoilage of the composition by microorganisms such as bacteria, molds and yeasts. Thus, the properly prepared composition has a long shelf life, i.e., it may be stored for extended periods, e.g., up to six months.

DETAILED DESCRIPTION OF THE INVENTION The polyglycerol ester composition of the invention may be utilized as a surfactant and viscosity modifier in a wide variety of formulations. It is provided as a liquid composition which, while flowable at room temperature, thickens to the desired viscosity upon the introduction of additional formulation ingredients. Broadly, the polyglycerol ester composition of the invention comprises about 1 to 5 wt% of a polyglycerol fatty acid ester, about 1 to 20 wt% of water, and about 75 to 95 wt% of a polyol. It generates the desired viscosity when incorporated into a personal care formulation.

Broadly, the polyglycerol esters have 6 to 12 glycerol units, more preferably, 6 to 10, 1 to 3 ester linkages, more preferably, 1 or 2. The fatty acids used for esterification may have from 10 to 20 carbon atoms, preferably, from 12 to 18.

Typical examples of polyglycerol esters are hexaglyceryl distearate, decaglyceryl mono- and dipalmitate, decaglyceryl mono and distearate, and mixtures thereof. The preferred polyglycerol esters are decaglyceryl distearate and decaglyceryl dipalmitate.

The polyols which can be utilized in the composition of the invention may vary widely and include any polyol which is compatible with the polyglycerol ester and the resultant personal care formulation. Typical examples of polyols which may be used include glycerol, polyglycerol, propylene glycol, sorbitol and hydrogenated starch hydrolysates. The preferred polyols are glycerol and sorbitol, and the most preferred is glycerol. Mixtures of polyols may also be used, such as, mixtures of sorbitol and glycerol or mixtures of sorbitol with polyglycerols.

The water utilized in formulating the composition of the invention should be of a high purity, e.g., deionized water or distilled water. The amount added is such that the water activity of the finished solution is below 0.7 and preferably below 0.5. The water activity is the relative humidity over the solution at a given temperature, and is measured with a hygrometer, such as the AquaLab, manufactured by Decagon Devices, Pullman, Washington. If the water activity level is maintained below 0.7, no preservatives need be added to the composition of the invention and a long shelf life is assured.

The composition of the invention is prepared by dissolving the polyglycerol ester in a solution containing the polyol and water. The dissolution is performed at a temperature of about 60 °C to about 80 °C with stirring, preferably, at about 75 °C. Following dissolution, the composition is cooled to room temperature.

The amount of water added to the composition of the invention should be sufficient to prevent gelation of the composition at temperatures from about 15 to 30°C. The amount needed varies depending on the particular polyglycerol ester employed. The viscosity of the solution should not be above about 150K cps at a temperature of 25 °C, as measured by a Brookfield Viscometer. Typical viscosities range from about 5K cps to 100K cps, preferably, about 10K cps to 40K cps, at a temperature of 25 °C.

Because of its long shelf-life, the composition of the invention may be prepared well in advance at a different location from the final product, as for example by the supplier of the polyglycerol esters. The shelf life is normally in excess of about 6 months.

The polyglycerol ester composition may be utilized alone to control the texture and flow properties of a personal care formulations, or in combination with a minor amount of other conventional viscosity modifiers such as, for example, sodium carboxymethyl cellulose, carrageenan or polyethylene glycol. Typically, the effective amount is about 0.5% by weight to about 2 wt%, preferably, about 1 wt%. These ranges are particularly applicable to a dentifrice.

The dentifrices may include a wide variety of conventional ingredients which are well known in the art. For example, abrasives such as silicas, calcium carbonate, dicalcium phosphate, calcium pyrophosphate, insoluble sodium metaphosphate, and silicic anhydride; humectants such as glycerol, sorbitol, hydrogenated starch hydroiysates, propylene glycol and polyethylene glycol; binders such as carboxymethyl cellulose, carrageenan, sodium alginate, locust bean gum, hydroxyethyl cellulose and polyvinyl alcohol; sweeteners such as sodium saccharin, glycyrrhizin salts, steviocide, neohesperidin dihydrochalcone, p-methoxycinnamic aldehyde and perillartine; flavors such as carvone, anethole, peppermint, spearmint and cinnamon; bactericides such as fluorides and chlorohexidine salts; phosphate compounds such as sodium phosphate; enzymes such as dextranase and amylase; anti- inflammatory compounds such as E-aminocaproic acid, tranexamic acid and allantoinate; anti-tartar agents; preservatives, such as benzoate and benzoic acid derivatives; colorants, such as FD&C dyes, D&C dyes and pigments; surfactants, such as sodium lauryl sulfate, sodium lauryl sarcosinate and others listed in Accepted Dental Therapeutics; buffers, such as phosphates, acetates and citrates; astringents, such as zinc chloride and aluminum salts; antibiotics, such as penicillin neomycin; fluoride compounds, such as sodium fluoride, sodium monofluorophosphate, stannous fluoride and organic fluoride; and, other effective compounds.

A typical dentifrice formulation which may be made using the composition of the invention is composed of 30 to 70 wt% of a polyol humectant, such as USP sorbitol; 10 to 50 wt% of an abrasive, such as Zeodent^® 1 13 or 165 (Zeodent is a trademark for precipitated silica abrasives made by the J.M. Huber Corp.); 0.3 to 2 wt% of the polyglycerol ester; and further includes a small amount of a flavoring agent, such as mint extract. The composition generally contains about 5 to 30 wt% water. To more fully illustrate the invention the following examples are presented. It will be understood, however, that these examples are not intended to limit the scope of the invention.

EXAMPLE 1

3.5 parts by weight of decaglyceryl distearate were dissolved with stirring in a solution of 82 parts by weight of glycerol and 14.5 parts by weight distilled water at 75 °C. Upon cooling to room temperature the solution remained flowable. A similarly prepared solution without the added water formed a non-flowable gel when cooled to room temperature. 30.5 g of the above polyglycerol ester composition were admixed and blended at room temperature with a dentifrice formulation consisting of 39.3 g of 70% USP sorbitol, 1.7 g water, 0.5 ml of mint extract, as well as 18.0 g Zeodent 113 and 5.5 g Zeodent 165. The polyglycerol ester composition and the dentifrice formulation were easily mixed by hand with a spatula until a smooth paste was formed. The resulting paste could be easily extruded from a tube and retained its integrity for a reasonable time when applied to a toothbrush.

The paste showed no syneresis after six month storage at 25 °C, illustrating that dentifrices prepared with the polyglycerol ester composition of the invention will maintain their viscosity over an extended period.

EXAMPLE 2 Part A The following polyglycerol ester compositions, in parts by weight, were prepared by blending the components at 75 °C:

A B C D

Glycerol 82 82 85 85

Decaglycerol Dipalmitate 3.5 1.7 1 0.8

Water 14.5 14.5 15 15 A B C D

Viscosity (25 °C), Centipoise 320K 64K 14K 7.5K

Flowability (25 °C) gels vise flows flows

The above compositions were prepared to establish the most useful range of ingredients compatible with the conventional dentifrice manufacturing process, while still producing a toothpaste with good shelf-stability.

Part B A therapeutic solution for forming a dentifrice was prepared by mixing of 195 parts by weight of 70% USP sorbitol, 1.2 parts by weight sodium fluoride, and 8 parts by weight water. To produce the dentifrice, 29.4 g of the polyglycerol ester Composition C were admixed and blended at room temperature with 40.8 g of the therapeutic solution, 18.0 g Zeodent 113, 5.5 g Zeodent 165, and 0.5 ml mint extract. The blending was easily done by hand at room temperature with a spatula.

Composition A, which contained 3.5 parts of the polyglycerol ester and 14.5 parts of water, formed a non-flowable gel when cooled to room temperature, and could not be blended with a dentifrice formulation. Composition B, in which the amount of polyglycerol ester was reduced to 1.7 parts, was less viscous than composition A, but was too viscous at room temperature to easily blend with a dentifrice formulation. Composition C; in which the amount of polyglycerol ester was reduced to 1 part by weight, contained a sufficient amount of water, about 15 parts, to flow easily at room temperature and blend with the dentifrice formulation to form a toothpaste. Composition C also contained sufficient amounts of polyglycerol ester such that, when the dentifrice was added, the composition thickened and formed a toothpaste which could be conveniently extruded from a tube, and which retained its integrity for a reasonable period of time on a toothbrush. A control formula without any polyglycerol ester, while flowable at room temperature and easily blended with the dentifrice formulation, did not develop sufficient viscosity following addition of the dentifrice ingredients to form a toothpaste with acceptable texture. The dentifrice paste produced using composition C did not develop any syneresis following storage at room temperature for 6 months; the paste made with composition D failed after one week.

Claims

What is claimed is: 1. A composition which comprises about 1 to 5 wt% of a polyglycerol ester, about 1 to 20 wt% water, and about 75 to about 95 wt% of a polyol, said composition having a viscosity of less than 150K cps at 25°C.

2. The composition of claim 1 , wherein the polyol is selected from the group consisting of glycerol, polyglycerols, sorbitol, propylene glycol, hydrogenated starch hydrolysates and mixtures thereof.

3. The composition of claim 1 , wherein the polyglycerol ester has from 6 to 12 glycerol units and from 1 to 3 ester groups.

4. The composition of claim 3, wherein the fatty acids portion of the ester has from 10 to 20 carbon atoms.

5. The composition of claim 1 , wherein the polyglycerol ester is hexaglycerol distearate, decaglyceryl monopalmitate, decaglyceryl dipalmitate, decaglycerol monostearate, decaglyceryl distearate, or mixtures thereof.

6. The composition of claim 1 , wherein said composition has a water activity of about 0.5 to about 0.7.

7. The composition of claim 1 , wherein the water present does not sustain the growth of microorganisms.

8. A method for producing a polyglycerol ester composition which comprises: dissolving a polyglycerol ester in a solution of a polyol and water at a temperature of about 60 °C to 80 °C; the amount of water being sufficient to prevent gelation of said composition at room temperature, so as to form a homogeneous liquid having a viscosity of less than 100K cps at 25 °C.

9. The method of claim 8, wherein said composition has a water activity of about 0.5 to 0.7.

10. The method of claim 8, wherein the water in the solution is not sufficient to sustain the growth of microorganisms.

1 1. A method for producing a polyglycerol ester composition which comprises dissolving at a temperature of about 60 °C to 80 °C, about 1 to 5 wt% of a polyglycerol ester in a solution comprising about 75 to 95 wt% of a polyol and about 1 to about 20 wt% of water.

12. A process for producing a dentifrice comprising: (a) formulating a polyglycerol ester composition by dissolving at a temperature from about 60 °C to 80 °C, about 1 to 5 wt% of a polyglycerol ester in a solution of about 75 to 95 wt% of a polyol and at least 1 wt% of water; (b) cooling the polyglycerol ester composition to room temperature; (c) blending at room temperature from about 25 to 40 wt% of said polyglycerol ester composition, based on the total weight of the dentifrice, with a formulation comprising a humectant, an abrasive and a flavoring agent.

13. The process of claim 12, wherein said formulation also contains a therapeutic agent.

14. The process of claim 12, wherein said dentifrice is substantially free of viscosity modifiers other than the polyglycerol ester.

15. The process of claim 12 wherein the polyglycerol ester composition has a viscosity less than 100K cps at 25 °C.

16. The process of claim 12, wherein said polyglycerol ester is decaglyceryl dipalmitate or decaglyceryl distearate, and said polyol is glycerol

17. A dentifrice comprising from about 10 to 50 wt% of an abrasive; about 0.3 to 2 wt% of a polyglycerol ester; 30 to 70% of a humectant and about 5 to 30 wt% water.

18. The dentifrice of claim 17, further comprising a flavoring agent.

19. The dentifrice of claim 18, further comprising a therapeutic agent.

20. The dentifrice of claim 17, wherein said dentifrice is substantially free of viscosity modifiers other than the polyglycerol ester.