CIP of c-4s80 11~5389 -:

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' Technical Description of the Invention ., The present invention is a formulation, which ~hen ln-- corporated in toothpastes containing a fluorine contalning compound and at least one compound selected from the group con-sisting of an insoluble alkali metal metaphosphate and calcium pyrophosphate that are held in unlined aluminum tubes, gives a paste which has acceptable pH values for efficacy of said flourine containing compound, acceptable texture, and a non-'' ' ' .

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CIP of C-4580 ~ tS3~9 corrosive effect on the inside of the unlined aluminum tube in - which it is held.
It has been recognized that toothpaste formulations ~, . which contain a polishing material ~7hich includes a major amount of an insoluble allcali metal metaphosphate cannot be placed in unlined aluminum tubes without corrosion problems being caused, .
One prior art attempt to overcome this problem is described in ~ U.S. Patent ~o. 3,624,199 to J. ~orfleet e~ al. which suggests - .
using 0.5 to 5%, by weight, benzyl alcohol and 0.15 to 2~, by .~0 weight, zinc oxide in such toothpaste formulations. :The.zinc ' oxide is identified as being responsible ~or,prevention of corrosion of the unlined aluminu~ tube containing such a tooth-paste formulation, whereas the benzyl alcohol is merely identi-j fied as-a desensitizing agent for tender are~s a.nd membranes in the oral cavity.
Although the use of zinc oxide alone.in a toothpaste~
wherein a desensitizing agent is not neededJ will inhibit the corrosion o unlined aluminum tubes, it has;been ound that the desired pH values have been exceeded for efficacy of the fluorlde compounds that may be contained thereîn, It'has been found that this problem can be solved by co~bining the zinc oxide with an.effective amount of a seleeted type of acidic pH adj.uster to both lower ~he pH of the paste to . the desired range of from about 5.5 to 6.8, preferably 5.5 - ~ -25 6.5~ and to prevent hindrance of the anti-corrosion ef~ect of the zinc oxide on the tube. Additional lmpro~ements in paste .. -2-:

CIP of C-4580 1~5389 texture can be obtained by incorporating in the formulation an effective amount for such improvement of trimagnesium phosphate.
The formulation of the present invention contains zinc oxide, an acidic pH ad3us~erJ which will be described in great-er detail below, and, optionally, trimagnesium phosphate. These components can be preblended to form such a formulation or can be added individually to a dental cream when the other solid constituents are added. In either case, the amount of zinc oxide which is used must be effective to inhibit any appreci-able corrosion of the unlined aluminum tu~be, the amount of the selected acidic pH adjuster must be effective to both main-tain a-pH in the toothpaste which is acceptable for any fluor~
ide compound which is present therein and to not hinder the anti-corrosive action of the zinc oxide,and the amount of tri-magnesium phosphate, if such is used, must be effective to bring about any desired improvement in texture. Generally the anti-corrosion formulation itself should consist essentially of from about ~20% to about 87% by weight, zinc oxide, from about 13~ to about 80~ by weight of the acidic pH ad3uster and from about 0% ~o about 7% by weight of triimagnesium phos-phate. Preferred amounts a~e.~bout 40-67% by weight zinc oxide, about 33-60% by weight ~H adjuster and about ~% - 5% by weight trimagnesium phosphate.

The amount of the above preblended formulation, or ~5 individual components thereof, which is added to the toothpaste must, as described above, be sufficient to give acceptable pH
values and texture and prevent corrosion of the unlined alumin-um tube. Generally, the final content of zinc oxide in the , ,~ , . ., ,,~,, :,. .

CIP of ~-4580 ~l~S389 -paste containing the above-described components will be from about n.Q5% to about 2.Q% b~ weight~preferably from about 0.1 to about 1.5% hy weight, the amount of acidic pH adjllster will be from about 0.05%
to about 3.0% by weight, preferably from abo~t 0.2% to about 1.5% by weight, and the amount of trimagnesium phosphate will be from about O to about Q.5~ hy weigh~, pre~e~ahly from about a.7% to about ~.2% by weight.
The acidic pH adjuster is selected from the ~roup con-sisting of weak organic or inorganic salts thereof which will ~;
lo form relatively insoluble aluminum compounds with the alum-inum tube which contains the toothpaste. Phosphoric acid and its acid salts (sodium aluminum phosphate /1:3.87, magnesium dihydrogen phosphate, aluminum dihydrogen phosphate, and am-monium dihydrogen phosphate) give the best long term results.
Other acidic pH adjusters which can be used include boric acid, oxalic acid and tartaric acid.
The above-described anti-corrosion formulation is adapted to be used in a fluorine toothpaste containing at least one compound selected from the group consisting of an insoluble alkali metal metaphosphate and calcium pyrophosphate. The tooth-paste formulations of this type are well known and contain a number of ingredients which will now be described in greater detail: -Polishin~ Agent: The water-insoluble polishing materia~
f the toothpaste formulation of interest herein contains a major proportion (that is, from about 50 percent to 100 percent, by .. j.. " .
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CIP ofC-4580 53~39 ~eight. of the polishing material) of an insoluble alkali metal metaphosphate or calcium pyrophosphate. The insoluble alkali metal metaphosphates which m~y be used are preferably t~e in-soluble sodium and potassium salts of polymetaphosphoric acid_ '; These materials are known in the art with the insoluble sodium metaphosphate being preferred. Such materials may be formed in any suitable manner, as illustrated by Thorpe's Dictionary o~
Applied Chemistry, Vol. 9 (4th ed.) pp. 510-511. The foxms o~
insoluble sodium metaphosphate known as Madrell's salt and 1~ Kurrol's salt are further examples of suitable materials~ These metaphosphate salts exhibit only limited solubility in water, and are commonly referred to as insoluble- metaphosphates. There is commonly present a minor amount of soluble phosphate mater-ial as impurities, usually of the order of a few percent such 1 . . . .
1~ as up to about 4~, by weight. The insoluble alkali metal meta-phosphate is typically employed in powder form of a 9ize such .
that no more than about 1~ of the material is larger than about 44 microns.
The polishing material may contain lOO~;nf the insoluble alkali metal metaphosphate or calcium pyrophosphate or any of these agents in major amount in admixture ~7ith a minor amount of such other agents or polishing agents as dicalcium phosphateJ
tricalcium phosphate, calcium pyrophosphate, hydrated alumina, calcium carbonate, and the like.

2, The polishing material content of the dental cream ca~
be varied, but will generally be from about 20 to about 75~ by eight of the total composition.

, CIP o~C-~580 Liquid Ingredients: In the dental cream formulation, liquids and so]ids are proportioned to form a creamy mass of desired consistency. In accordance wlth this invention, the creamy mass is packaged in a collapsible unlined aluminum tube In generaIJ the liquids in ehe dental cream will com-- prise chiefly water, glycerine, aqueous solutions of sorbitol, propylene glycol, polyethylene glycol ~00 and the like, includ-ing suitable mixtures thereof. -It is advantageous to sometimes use a mixture of both water and a humectant, such as Olycerine or sorbitol. The total liquid content will generally be from about 20 to about 75~ by weight of the formulation. It is pre-ferred to also use a binder or gelling agent in dental creams such as the natural and synthetic gums and gumlike materials, e.g., Irish moss, gum tragacanth, sodiu~ carboxymethyl cellulose, polyvinylpyrrolidone, and the like, usually in an amount up to about 1~, by weight, and prefera~ly from about 0.2 to about 5~, by weight, of the formulation.
Surface Active A~ents: Organic 5urface-active agents used in the toothpaste formuations of in~erest herein can be used to assist in achieving thorough and' complete dispersion of the instant compositions and to make them more cosmetically acceptable. The organic surface active material may be anionic, nonionic~ ampholytic, or cationic in nature, and it is pre-ferred to employ as the surface active agent a detersive mater-ial which imparts to the composition detersive and foaming prop-erties. Suitable materials are the water-soluble salts of higher fatty acid monoglyceride monosulfates, such as the sodium salt of CIP of C-4s~o the monsulfated monoglyceride of hydrogenated coconut oil fatty acids, the higher alkyl sulfates, such as sodium lauryl sulfate>
the alkyl arylsulfonates, such as sodium dodecyl benzene sul-onate, the higher alkyl sulfoa~etates, the higher fatty acid ester of 1,2 dihydroxy propane sulfonates, and the substantially saturated higher aliphatic acyl amides ~f lower aliphatic amino carboxylic acid compounds, such as those having 12 to 16 carbons in the fatty acid, alkyl or acyl radicals, and the like. Ex-amples of the last-mentioned amides are N-lauroyl sarcosine, and .
the sodium,potassium, and ethanolamine s~lts of N-lauroyl,-~-~yxistoyl or N-palmitoyl sarcosinates. which should be substan-t`ially free from soap or similar higher ~atty acid.material -which tends to.substantially reduce the effect of these compounds.
It is preferred to use rom about 0~05 to 5% by weight `

f the foregoing surface-active materials in the instant dental ~! ~ cream-Fluoride Compounds: The toothpaste compositions of interest herein also contain a fluorine-containing compound ha~-ing a beneficial effect on the care and hygiene of the oral cavity, e.g., diminution of enamel solubility in acid~and pro- -~ection of the teeth against decay. Examples thereof include sodium fluoride, stannous fluoride, potassium fluoride, potassium stannous fluoride (Sn~2KF), sodium hexafluorozircon :ate, and sodium monfluorophosphate~w~ich is preferred. TEI~se 2, materials, ~Jhich dissociate or release fluorine-containing ions in water, suitably may be present.in an ~ffective but nontoxi~
amount, usually ~7ithin the range of about 0-01 to 1~ by weight of the water soluble fluorine content thereof. It is necessary - that the pH of the formulation be between about 5.5 and 6.8 7.

~ 5389 CIP of C-4580 when these compounds are used.
Flavorin~ A~ents: Any suitable flavoring or sweeten-ing sialagogue may be cmployed in formulating the dental cream of the instant invention. Examples o~ suitable examples of flavoring consituents include flavoring oils such as the oils of spearmint, peppermint, clove, wintergreen, sassafras, Sage~
eucalyptus J marjoram, cinnamon, lemon and orange, as well as sodium salicylate. Suitable sweetening agents include lactose~
- ~ maltose, sorbitol, and saccharine. S~ita~lyJ the total amount of sialagogue may comprise from about 0.5 to about 6p or more of the dental cream of the instant inYention~ .
Other ingredients: Various other materials may be in-corporated in the dental creams of this invention. Examples thereof are coloring or whitening agents, preservatives ~e.g., sodium benzoate and the esters of the hydroxybenzoates, which are usually considered necessary from a commercial standpoint), silicones and other constituents such as desensitizing agents.
These adjuvants can be incorporated in the instant compositions in conventional amounts and ~ill not substant;ally adversely affect the properties and characteristics of the formulation formed thereby.
The following Examples illustrate certain preferred embodiments of the present invention CIP of C-4580 ~531!39 This Example illustrates the fo~mation of a toothpaste ~ormulation containing the stabilizer formulation of ~he pres-ent in~ention.
A general procedure for forming the toothpaste includes the following steps: -1. Weigh the desired amounts o~ thickener, sweetening agent, preservative and sodium monofluorophosphate and premix said ingredients with a spatula;
2. Place a beaker on a ringstand and a mixer in said beaker. Add sorbitol and glycerine and mlx them until they are unifor~. The ingredients from Step 1 are then added slowly and are mi~ed. .Water is added and mixing is continued; and

3. The beaker containing the mixture from Step 2 Ls weighed and water is added if needed to bring the mixture to the requisite weight. The insoluble sodium metaphosphate is then added and anhydrous dicalcium phosphate, zinc oxide, boric acid, and trimagnesium phosphate are added and are mixed into the formulation with a spatula until a uniorm consistency is noted. Detergent and flavor can then be mixed in until a uni-form paste is obtained. The mixture is milled into a stainless steel beaker and the batch is deaerated- ~t is then trans-ferred to filling equipment and is inserted into an unlined aluminum tube.
The above procedure was used to make the following formulati~n:

l~S389 CIP of C-4580 Ingredient(s) ~ ~by we Insoluble sodium metaphosphate ~0.25 Water 19.39 Sorbitol (70% by weight) . ~4.oo Glycerine (95~ by weight) 12.80 Anhydrous dicalcium phosphate . 5.oo Misc. agents tBinder, Flavoring,.
Preservative, etc.) 4.~o - Sodium N-lauroyl sarcosinate lo detergent 2.00 Zinc Oxide l.oo Sodium monofluorophosphate . o 76 ~oric acid o 50 Trimagnesium Phosphate 0.1.0 The formulation had a pH in the range of about 5.5 to 6.5 and had a smooth texture. I~hen placed in an unlined alum-- inum tube for one week's storage at c~ C., the formulation caused no appreciable corrosion of said tube.

The general procedure used in ExampLe 1 was utilized .:
to form toothpaste formulations containing the following components: . -- 1 o -CIP of- ~-4580 ~l~S389 A B
In~redients - ~% by weight) Insoluble sodium metaphosphate41.85 40.25 Anhydrous dicalcium phosphate 5 oo s.oo Sodium ~onofluorophosphate 0 76 o.76 Sodium N-lauroyl sarcosinate 2 00 2.00 Glycerine 12.80 12.80 Sorbitol 14.00 14.00 Misc. agents (binder, flavorin~4.20 4.20 lo Water preserva~ive) lg,39 19.39 . . .
Zinc oxide --- . 1.00 Boric acid - ___ 0 50 Trimagnesium phosphate --- 0.10 Formulation A, set forth a~ove, corroded unlined aluminum tubes when placed therein whereas formulation B did .
not.
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This example illustrates both corrosive (formulation A, ; below) as well as non-corrosive ~formulation B, below) formula-tions using calcium pyrophosphate as the polishing agent. The -same general mixing procedure of Examp1e 1 was used and both foxmulations were placed in unlined alumlnum tubes. The follow-in~ ingredients wexe used: A B
Ingxedients ~ by weight) Calcium pyxophosphate ~5.oo 43~40 Glycerine (95~) 4 0O ~ 0O
Sodium caxboxymethyl cellulose (medium viscosity)1.20 1.20 Saccharin ~.20 0.20 CIP of C-4580 ~53~
A B
Ingredients (% by weight~
Sodium benzoate, U.S.P. - o.lo 0.10 Sorbitol (70~) 18.00 18.00 Distilled water 23.00 2,.0o Flavoring l.oo l.Oo Sodium lauryl sulfate (20~) .
in glycerine (80~) 7.50 7.50 Zinc oxide , --- 1.00 Boric acid . ; -~ 0 50 Trimagnesium phosphate .~ 0.10 This Example illustrates the effect o removing one or ~ore of the components of the anti-corrosion formulation of the present invention. The.table sets forth the various formula-. tions (A-D) which were prepared:: .
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o 1 85~ aI3 CIP ofc-458o 53~39 Each of the toothpaste formulations set forth in the table were placed in resin coaeed aluminum tubes and unlined aluminum tubes, respectively. The paste pH and texture were noted. The tubes were examined after they had been stored for 5 7 days at 50C. The following results were obtained:
Formulation Paste pH Texture Tube A 5.5-6-5 Acceptable Coated - Not corroded A 5-5-6-5 Bubbly Unlined - Corroded B 7.5-9.0 Acceptable Coated - Not corroded B 7-5 ~9 Acceptable Unlined - ~ot corroded C 5-5-6-5 Acceptable Coated - Not corroded C 5.5-6.5 Acceptable Unlined - ~ot corroded D 5.5-6.5 - Acceptable Coa;ted - ~ot corroded D 5.5-6.5 Acceptable Unlined - Not corroded' ; 15 E 5.5-6-5 Acceptable Coated - Not corroded E 5.5-6-5 Acceptable - Unlined - Not corroded Formulation A which did not contain any of the compon-ents of the claimed invention yielded a paste having an unaccept-able, bubbly texture and produced corrosion in the unlined alum-inum tube. Formulation B containing only zinc oxide avoided theproblem of corrosion but gave a paste having a pH which is too high ~or the effectiveness of the fluorine compound contained in the toothpaste. Formulation D, containing trimagnesium phosphate, produced a slightly smoother, and more acceptable, paste texture than Formulation C, which was acceptable.
E ~ PLE 5 This Example illustrates the importance of utilizing, as acidic pH adjusters, compounds which forms insoluble compounds with aluminum. The formulation described in Example 1 was used ,~ during the tests. The Table sets forth the results:

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U~ o 085 ,~ F aI~ l 5 CIP of C-4580 53~9 Footnotes:
(1) This adjuster is acceptably effective at a level of about 0.25 to about 1.5~ by weight of the stabilizer formulation of zinc oxide~pH adjuster/~optio~ally) trimagnesium phosphate. A
suitab~e product of this type is availab~e under the trademark LEVAIRlY from Stauffer Chemical Company, Specialty Chemical Di-vision, l~estport, Connecticut. Some slight development of a grainy texture was observed in some pastes containing this ad-juster.
~2) Also called magnesium d~hydrogen phosphate. Its formula is Mg (H2PO~) 2 -- ,, ~3) Also called aluminum dihydrogen phosphate. Its formula is Al~H2PO4) 3 .
. . .
~ 4) Also called ammonium dihydrogen phosphate. Its formula is NH4H2PO~.
(5) The pH values of pastes containing th}s additive tended to drift upward with time and during a one to eight month~storage often was above the desired value.
~6) Some off-color and slight thickening of the paste was noted after one week storage at 50C. when used with relatively low - levels of zinc oxide, e.g., O. 5'5 Zn/0.25~ H3PO4. A o.8% ZnO/
o.5~ H3PO4 mixture kept the paste pH at 6.2 for twenty one months storage at room temperature without corrosion, off-color, or thickening.
(7) Paste aged at 5~C. for one month containing this additive showed significant thickening, whereas at room temperature the thickening was much less.

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CIP of C-4580 r ~ 5 389 The salts and acids listed on the foregoing Table which produce corrosion in the unlined aluminum tube are those which do not form relatively insoluble aluminum compounds with the aluminum tube material in wlich the ~oothpaste formulation is packaged.
~ It has been found that when relatively high values of zinc oxide are used relative to the acidi~ pH adjuster, it is possible for the pH of the toothpaste formulation to drift up-wardly upon prolonged ctorage due co the dynamic nature of the lo system. For example use of a 2:1 weight ratio of zinc oxide to boric acid (1~:0.5% by weight of the toothpaste ormulation) gave a paste pH after one month's storage of 6^5 and after six .. ~ . .. . . . .
months storage of 7.3. This can generally be overcome by using a lower rel~tive amount of zinc oxide or a higher relative am- -;; 15 ount of the acidic pH adjuster. For example, equal weight am-ounts of zinc oxide and boric acid (o.8%:o.8% by weight based on the weight of the toothpaste) produced a pH o 6.3 after six months storage. It is well within the ability of a person of ordinary skill in the art to adiust the zinc oxide: pH ad-juster ratio so as to obtain the desired pH values after de-sLred storage times.
The foregoing is illustrative of certain preferred em-bodiments of the claimed invention and is not to be construed in a limiting sense- The scope of protection that is sought is set forth in the claims which follow -.. . ~ ,.