CA1039193A - Toothpaste - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A toothpaste comprising a vehicle comprising a humectant and dispersed in said vehicle a dental abrasive which is principally material having a particle size of about 2 to 20 microns, a silica content of at least about 70% and an amorphous x-ray structure, the improvement wherein said toothpaste is free of gum or other vehicle-soluble thickener and said principal abrasive is an alkali or alkaline earth metal aluminosilicate abrasive having an oil absorption value of up to about 165, said toothpaste being transparent and particularly useful in tropical climates since it is resistant to biological and chemical attack.

Description

1~)391~

Toothpastes conventionally comprise finely divided dental abra-sives dispersed in humec~ant vehicles containing thickening and/or gelling agents.
One aspect of this invention relates to a toothpaste comprising a vehicle comprising a humectant and dispersed in said vehicle a dental abra-sive which is principally material having a particle size of about 2 to 20 microns, a silica content of at least about 70% and an amorphous x-ray structure, the improvement wherein said toothpaste is free of gum or other vehicle-soluble thickener and said princip~l abrasive is an alkali or alkaline earth metal aluminosilicate abrasive having an oil absorption value of up to about 165.
The toothpastes of this invention are substantially free of gum or other water-soluble (or vehicle-soluble) thickener and preferably contain as principal abrasive a sodium alu~inosilicate abrasive having an oil absorption value (A.S.T.M. D. 281-31) of up to about 165. A low density silica gel may be present in admixture with the aluminosilicate. Preferably the total oil absorption value of the dispersed solid ingredients of the toothpaste (which total value is obtained by multiplying the oil absorption value of each such ingredient by the percentage of that ingredient in the toothpaste) is in the range -- 1 -- ., ~, 10.39l93 of about 40 to 60. It is found that such toothpastes have excellent rheological characteristics. They have very good body, extrude easily from a conventional toothpaste tube, retain a shiny appearance without visible dulling or hazy skin formation for considerable periods after extru-sion, have a desirable short texture and are not undesir-ably stringy or grainy, behave well in automatic tube-filling equipment, have good tooth cleaning, polishing and mouth feel characteristics and (in transparent types of toothpastes) good clarity. In contrast to the products described in U.S. Patent 3,689,637 toothpastes of this in-vention show such characteristics even in the absence of a polyethylene glycol of average molecular weight above about 800. As ~ill be seen in the following Examples, polyethylene glycol may be omitted entirely or a lower molecular weight polyethylene glycol may be employed.
The toothpastes of th~s invention lend themselves particularly to formulation and use in tropical climates.
Their ingredients are resistant to biological and chemical attack.
The sodium aluminosilicate abrasive preferably has a refractive index of about 1.44-1.47 and contains at least about 70% silica, up to about 10% alumina (and more prefer-ably at least about 0.5~0 alumina), up to abput 20~o by weight of moisture and up to about 10% by weight of sodium oxide. The preferred moisture content is about 10-20% by weight measured by loss on ignition at 1000 C and the typi-cal content of sodium oxide is about 5-10% by weight. One may employ as the abrasive an aluminosilicate having an oil absorption value of about 150-160 g/100 g and a packed bulk 1(13~19~
density below about 0.2 g/cm3. Greater cleaning power is obtained however, when the aluminosilicate has an oil absorption value below about 130 g/100 g, e.g. about 75-115 g/100 g, and its packed bulk density is above about 0.25 g/cm3 (e.g. about 0.3-0.4 g/cm3). Especially suitable are materials in which the SiO2:A1203 mol ratio is at least about 45:1. Aluminosilicates of other alkali metals, e.g.
K, or of alkaline earth metals, e.g. Ca or Ba, may replace all or part of the sodium aluminosilicate; aluminosilicates of two or more of the metals may be used.
The total proportion of aluminosilicate abrasive is in the range of about 1 to 50% of the toothpaste, prefer-ably about 5 to 40%, such as about 16 to 30%.
Th~ low density silica gel (i.e. dehydrated silica hydrogel) is typically a material having a particle size in the range of about 1 to 5 microns (such as about 3 t~
4 microns), a density (centrifuge) of well below 0.25 g/cm3, generally within the range of about 0.10 to 0.20 (such as about 0.15) g/cm3. It may be a silica aerogel. Its oil absorption value is at least about 300 and usually below about 350 (e.g. about 305-315) pounds per 100 pounds and its surface area is below about 350, and generally well above 100 m2/gram, e.g. about 250-320 m2/gram. The product known under the trademark Syloid 244 is typical of this type of material. When used, it is present in amount less than the amount of aluminosilicate and preferably up to about 10%
of the weight of the toothpaste, e.g. within the range of 1 to 9%, such as about 6 to 9%.
The vehicle of the toothpaste is made up primarily of a humectant such as glycerol or sorbitol, usually in admixture with water. Taken together, the proportion of these liquids in the toothpaste is advantageously in the range of about 40 to 90%, preferably about 60 to 80%
and still more preferably about 65 to 75%. (Sorbitol, generally present in solutions, typically 70%, in water, is considered as a liquid for this purpose). Additional water, (beyond that present if sorbitol is employed) is preferably about 5 to 35%, more preferably about 15 - 20%, of the total liquids.
As indicated, a polyethylene glycol may be present in the vehicle. These materials are well known in the art. Typically, they are mixtures of po~ymeric molecules of different degrees of polymerization; the graph showing the distribution of molecular weights (e.g. the graph plotting the degree of polymerization vs. per cent by weight) is typically a smooth "bell" shaped distribution curve. Such materials are described in the 65 page book-let "Carbowax Polyethylene Glycols" F-4772E, published by Union Carbide Chemicals Company. The materials of average molecular weights in the range of 200 to 600 are clear liquids at 25 C (although the 600 average molecular weight material begins to freeze to a soft waxy material at about 25C), while those of average molecular weight 1000 to 20,000 are white waxy solids. Especially good results are obtained when the average molecular weight of the polyethylene glycol is about 600. The proportion of polyethylene glycol is generally below about 10%, e.g. in the range of about 1 to 8%
and more preferably about 3 to 7.5% of the toothpaste.
The toothpaste may also contain surface active agent, e.g. to achieve increased prophylactic action, assist in 1039~9~
achieving thorough and complete dispersion of the instant compositions throughout the oral cavity, and render the in-stant compositions more cosmetically acceptable. The or-ganic surface active material may be anionic, nonionic, ampholytic or cationic in nature, and it is preferred to employ as the surface active agent a detersive material which imparts to the composition detersive and foaming properties. Suitable types of such detergents are water soluble salts of higher fatty acid monoglyceride monosulfates~ such as sodium salt of the monosulfated monoglyceride of hydrogenated coconut oil fatty acids, higher alkyl sulfates, such as sodium lauryl sulfate, alkyl aryl sulfonates such as sodium dodecyl benzene sul-fonate, higher alkyl sulfoacetates, higher fatty acid ester of 1,2 hydroxy propane sulfonates and the substantially saturated higher aliphatic acyl amides of lower aliphatic amino carboxylic acid compounds, such as those having 12 to 16 carbons in the fatty acid, alkyl or acyl radicals, an~ the like. Examples of the last mentioned amides are N-lauroyl sarcosine, and the sodium, potassium, and ethanolamine salts of N-lauroyl, N-myristoyl or N-palm-itoyl sarcosine, which should be substantially free from soap or similar higher fatty acid materials which tends to substantially reduce the effect of those compounds. The use of these sarcosine compounds in dentfrice compositions of the present invention is particularly advantageous since these materials exhibit a prolonged and marked effect in the inhibition of acid formation in the oral cavity due to carbohydrates breakdown in addition to exerting some reduction in the solubility of tooth enamel in acid solu-tions. ~3~
Other particularly suitable surface active materialsinclude nonionic agents such as condensates of sorbitan mo-nosterate with approximately 60 moles of ethylene oxide, condensates of ethylene oxide with propylene oxide conden-sates of propylene glycol (available under the trademark '~luronics") and amphoteric agents such as quaternized imi-dazole derivatives, which are available under the trademark ~iranol~ such as Miranol C2M. Cationic surface active germicide and antibacterial compounds such as di-isobutyl-phenoxyethoxyeth~l dimethyl benzyl ammonium chloride, benzyl dimethyl stearyl ammonium chloride, tertiary amines, having one fatty alkyl group ~of from 12 to 18 carbon atoms) and two (poly) oxyethylene groups attached to the nitrogen (typi-cally containing a total of from about 2 to 50 ethanoxy groups per molecule) and salts thereof with acids, and compounds of the structure (I 2 2 )z ~ (CH2CH20) H

R N-CH2CH CH N (CH2cH2o)yH

where R is a fatty alkyl group containing from abou* 12 to 18 carbon atoms, and x, ~ and z total 3 or higher, as well as salts thereof with mineral organic acids, may also be usedO It is preferred that the total amount of surface-active agent be about 0.~05-5% by weight, prefer-ably about 1-3%, of the dentif~ice.
Various other materials may be incorporated in the oral preparation of this invention. EXamples thereof are coloring or whitening agents, preservatives, silicones, chlorophyll compounds, ammoniated materials, such as urea, iO3glW
diammoniumphosphate and mixtures thereof, and other consti-tuents. Each of these adjuvants may be typically incor-porated in the instant toothpastes in amounts up to about 5%.
The toothpaste may also contain antibacterial agents in amounts of abput 0.01-5%. Typical examples of such agents, are guanidines, biguanides and amines such as:
N -(4-chlorobenzyl)-N5-2,4-(dichlorobenzyl) biguanide;
p-chlorophenyl biguanide;
4-chlorobenzhydryl biguanide;
4-chlorobenzhydrylguanylurea;
N-3-lauroxypropyl-N -p-chlorobenzylbiguanide;
1,6-di-p-chlorophenylbiguanidohexane;
l-(lauryldimethylammonium)-8-(p-chlorobenzyldimethyl-ammonium) octane dichloride;
5,6-dichloro-2-guanidinobenzimidazole;
N -p-chlorophenyl-N -laurylbiguanide;
5-amino-1,3-bis(2-ehtylhexyl)-5-methylhexahydro-pyrimidine and their non-toxic acid addition salts.
Suitable flavoring or sweetening sialogogues may be employed in formulating a flavor for t~e compositions of the present invention. Examples of suitable flavor-ing, constituents include the flavoring oils, e.g. oils of spearm~nt, peppermint, wintergreen, sassafras, clove, sage, eucalyptus, marjoram, cinnamon, lemon and orange, as well as methyl salicylate. Suitable sweetening agents include sucrose, lactose, maltose, sorbitol, sodium cyclamate and saccharine. Suitably, flavor and sweeten-ing agent may together comprise from about 0.01 to 5%

103~
more of the compositions of the instant invention.
The compositions of the present invention suitably may also contain a fluorine-containing compound having a beneficial effect on the care and hygiene of the oral cavity, e.g. diminution of enamel solubility in acid and protection of the teeth against decay. Examples thereof include sodium fluoride, stannous fluoride, potassium fluoride, potassium stannous fluoride (SnF2.KF), sodium hexafluorostannate, stannous chlorofluoride, sodium fluoro-zirconate and sodium monofluorophosphate. rhese materials, which dissociate or release fluorine-containing ions in water, suitably may be present in an effective but non-toxic amount, usually within the range of about 0.01 to 1% by weight of the water soluble fluorine content there-of.
Other dental abrasive agents may be present in the toothpaste. When these have a refractive index substan-tially different from that of the vehicle, it is prefer-able that they be present in such form and in such amount as not to make the toothpaste opaque; this makes it pos-sible to obtain various visual esthetic effects. For in-stance, such abrasive agents may be employed in the form of the known visible palpable agglomerates of the fine, microscopic sized abrasive powders (e.g. about 2 to 20 microns in particle diameter), which agglomerates (having diameters in the range of, say, about 200 to 800 microns) are present in minor amounts (e.g. about 1 to 5~0) so as to give the toothpaste a speckled appearance, the speckles be-ing visible through the otherwise transparent toothpaste;
the speckles are of such nature as to be broken down to 1039~93 invisible impalpable particles in the mouth by the pres-sure and movement of the toothbrush. Or the added abras-ive agents may he present in amount well below 5% (e.g.
1/2% or 1%) together with a visible effect material, such as iridescent particles (which may also have an abrasive or cleaning action), giving a toothpaste having a sparkling appearance.
The following Examples are given to illustrate this invention further. In this application all proportions are by weight unless otherwise indicated.
Examples 1-9 Dental creams are prepared according to the formu-lations shown in Table I. In each case the toothpaste is made by adding the solid ingredients to a mixture of the liquids and then deaerating in vacuo and adding chlo-roform under non-aerating conditions before placing the mixture in conventional collapsible toothpaste tubes.
The tubes are stored at room temperature for several days before the product is tested.
The product extrudes easily as a ribbon from a toothpaste tube, has good body and is non-stringy; also, after a ribbon of the toothpaste is extruded, there is little or no tendency for slow oozing of the material to continue after the extrusion pressure has ended. It be-haves well in automatic tube-filling equipment in which the toothpaste is extruded (intermittently) into succes-sive collapsible tubes from a nozzle and in which it is desirable that there be no dripping or stringing from the nozzle after it leaves one tube and before it enters the next one. ~ ribbon of the pmoduct extruded from the tube maintains its clear shgny appearance for a consider-able time.
After aging 9 weeks at 120 F in a toothpaste tube, the product maintains its desirable properties; its body and viscosity rise but it is still easily extrudable.
The formulations of Examples 2-9 are particularly suit-able in terms of ribbon characteristics and resistance to plug formation at the neck of the tube on aging.
It will be seen that Examples 4 and 5 employ large amounts of the sodium aluminosilicate without any low den-sity silica gel thickener.

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O ~1 O O O O ~ t~ Q. ~1 v ~ u~ ~U2 u~ tn o ~ u~ ¢ u Footnotes for Table I
(a) The sodium aluminosilicate has the following empirical composition: silica about 72%; alumina about 8%; sodium oxide about 7~0; water (ignition loss at 1000 C) about 12%~ It has a surface area of about 110 m /g, a particle size of about 4 microns (the particles being aggregates of materi-al of ultimate particle size of 35 millimicrons), an oil absorption value of about 160 g/lOOg and a pH (for a 4~o slurry in water) of about 10. 5.

(b) The sodium aluminosilicate is "Zeo 49~
having the following approximate analysis: 78% SiO2 ~ 1%
A1203, loss on ignition 10.6%~ Na20 (by difference) 10.3~o~
Its bulk density is 18-25 lbs/ft (i.e. about 0~3~0.4 g/cm ); its surface area (B.E.T.) is less than 300 m /g and its oil absorption is about 80-110 g/100 g. Its re-fractive index is 1.450-1.465 and its pH (in 5Yo aqueoùs slurry) is 6.0-7.5.
(e) The polyethylene glycol has an average molecu-lar weight about 600 (e.g. 570 to 630~ corresponding to an average degree of polymerization of about 13-14); its freezing point is about room temperature (about 20-25 C); its molecular weight distribution is as follows:
D.P. 6 7 8 9 10 11 12 13 14 15 ~o 0.5 1.5 3 4~8 6~1 7.8 9 10 11~5 11.
D.P. 16 17 18 19 20 21 22 23 24 % 11 9 5 3.5 2.6 2 1.3 0.8 0~8 *TRAD~ MARK

i~33~93 "D.P." means degree of polymerization, i.e., the number of ethylene oxide units in the molecule; '~" means percent by weight; the figures in the above tabulation are based on the graph of '~olymer Distribution in Carbowax polyethylene glycols...." in the 65 page booklet llCarbowax Polyethylene Glycols" F-4772E, published by Union Carbide Chemicals Com-pany.
(f) The polyethylene glycol has an average molecular weight of about 1500 (Carbowax 1500-trademark; see the Union Carbide booklet mentioned above).
(g) The polyèthylene glycol has an average molecular weight of about 4000 (Carbowax 4000-trademark; see the Union Carbide booklet mentioned above).
(c) 70% sorbitol is a 70/30 sorbitol/water mixture.
(d) The color solution is a m;~ture of % solutions of F, D and C colors~ e.g. Red #2 and Yellow #6.
(k) The speckles are of a si~e visible to the naked e~e (about 250 - 420 microns particle diameter) and are com-posed of a blend of 80% pol~ethylene of 1500 molecular weight (softening point 102C) and 20~ zirconium silicate dental pol-ishing agent of fine particle size.
(h) The alumina is alpha alumina in the form of flakes, as described in U.S. Patent 3,121,623, specifically flakes having a mean (by weight) particle diameter of about 4 microns.
(i) The iridescent flakes are titanium dioxide coated mica flakes (Timica Sparkle-trademark) ranging in si~e from about 15-40 microns; their thickness is about 0.7 microns, their titanium dioxide coatings (on both faces of each flake) are of anatase;
and their composition is about 20% anatase, 80% mica.

It is also within the broader scope of this invention to substitute for all or part of the aluminosilicate (as in Ex. 4 and 5) a silica gel (or a silica alumina gel) of ~nter-mediate density, such as that known under the trademark Syloid 74 (oil absorption about 200 g/lOOg) or e~en of high density, such as that known under the trademark S~vloid 63 (oil absorp-tion about 60 g/lOOg).
It is also within the broader scope of this invent~ion to substitute a precipitated silica or silica-alumina for all or part of the low density silica gel. As is well known in the art, both silica gel and precipitated silica are commonly made by addition of an acid (e.g, sulfuric acid) to soluble silicate solution (e.g. aqueous sodium silicate); see Encyclopedia of Chemical Technology (Kirk-Othmer), 2nd edi-tion Vol. 18 p. 61-62 for instance. One suitable type of precipitated silica or silica-alumina is that known under the trademark Zeosyl 200 XP, which contains about 90% silica (e.g.
89-92%), about 1% alumina (e.g. 1-1.2%), some 5% or so of water (e.g. published specifications specify a maximum loss of 7% on heating at 105 C) and at most about 3% Na2~04 as impurity, and has a particle si~e (aggregate) of about 2 nicrons, a specific gravity (at 25C) of 2.0, a bulk density of about 0.12 to 0.16 g/cm3, an oil absorption of about 200-230 of per lOOg, a pH (in 5% suspension in water) of about 7 (e.g. 6.5-7.5), a refractive index of about 1.45 (e.g. 1.45-1.46). This material may be substituted directly for all or part of the low density silica gel of an~ of Examples 1 to 9 above. The precipitated silica or silica-alumina serves as a thickener. The silica content of the thickener is at least about 70%.

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a toothpaste comprising a vehicle comprising a humectant and dispersed in said vehicle a dental abras-ive which is principally material having a particle size of about 2 to 20 microns, a silica content of at least about 70% and an amorphous x-ray structure, the improve-ment wherein said toothpaste is free of gum or other ve-hicle-soluble thickener and said principal abrasive is an alkali or alkaline earth metal aluminosilicate abrasive having an oil absorption value of up to about 165.

2. A toothpaste as in claim 1 in which the total oil absorption value of the dispersed solid ingredients of the toothpaste is in the range of about 40 to 60 and said prin-cipal abrasive is sodium a1/2uminosilicate.

3. A toothpaste as in claim 2 in which said prin-cipal abrasive has an oil absorption value of 75 to 115 g/100 g.

4. A toothpaste as in claim 2 which also contains particles of siliceous thickener which comprises silica gel, silica-alumina gel, precipitated silica, or precipi-tated silica-alumina, said siliceous thickener having a bulk density of about 0.1 to 0.2 g/cm3.

5. A toothpaste as in claim 4 in which the particle size of said siliceous thickener is about 1 to 5 microns.

6. A toothpaste as in claim 2 in which said sodium aluminosilicate is substantially the sole abrasive in the toothpaste.

7. A toothpaste as in claim 2 containing about 1 to 10% of polyethylene glycol of average molecular weight about 600.

8. In a toothpaste comprising a vehicle comprising a humectant and dispersed in said vehicle a dental abrasive which is principally material having a particle size of about 2 to 20 microns, a silica content of at least about 70%
and an amorphous x-ray structure, the improvement wherein said toothpaste is free of gum or other vehicle-soluble thickener and the total oil absorption value of the dispersed solid ingredients of the toothpaste is in the range of about 40 to 60.

9. A toothpaste as in claim 7 containing about 1 to

10% of polyethylene glycol of average molecular weight about 600.