Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
563
This application is a division of Canadian Patent
application Serial No. 285,885 filed August 31, 1977.
The present invention relates to dentifrice
compositions and more particularly to dentifrice compositions such
as toothpastes containing therapeutic agents and/or polishing
agents and other ingredients~ wherein the composition also
contains a controlled amount of alkaline earth metal ion to
prevent corrosion and staining when placed in unlined aluminum
tubes over extended period~ of ~toraye.
This application is related to our copending Canadian
application 298,783 filed March 13, 1978.
DESCRIPTION OF THE PRIOR ART
.
~roadly speaking, there are two type~ of modern day -
dentifrices on the market which may be described as opaque and
clear-gel dentifrice compo8ition8.
Each type of above mentioned dentifrice i~ marketed
under two different versions:
A. Cosmetic Type
~. Thexapeutic Type
A cosmetic type toothpaste is one which contains no
fluoride and is promoted fo~ whitening and brightening of
the teeth. A thexapeutic toothpaste, however, contains fluoride
as anti-caries agent.
Therapeutic dentifrice compositions such as toothpastes,
normally contain a fluoride therapeutic agent such as stannous
fluoride, monofluorophosphate, or derivatives thereof, as well as
polishing agents, humectants, and other materials. These
.
63
compositions are usually placed in aluminum or plastic tubes for
sale on the commercial market. It is usually preferred to use
aluminum tubes but it has been discovered that when such toothpast~
compositions contain a therapeutic fluoride compound, a reaction
with the interior of the unlined aluminum tube takes place so
that staining and other corrosive action occurs apparently
because of some reaction or incompatibility between the bare
aluminum surface and one or more of the materials in the too-th-
paste. This incompatibility appears in the form of gas
production, swelling of the tube, corrosion, and black stains on
the inside surface of unlined aluminum container. Accordingly,
the standard practice in the marketing of ~herapeutic toothpastes
today has been to line the aluminum tube with a plastic, lacquer
or other material, which therefore substantially adds to the cost
of packaging and marketing the toothpaste.,
Many prior art attempts have been made to solve this
problem because unlined aluminum tubes a~e much more economical
to use and are generally lighter in weight than the lined tubes.
For e~ample, U.S. Patents 3,662,060 and 3,62g,199 disclose
compositions which are said to overcome this problem. Further,
U.S. Patent 3,678,155 discloses that monofluorophosphate ions
prevent corrosion of unlacquered aluminum tubes when the
toothpaste contains milled alpha-alumina trihydrates as an
abrasive. Also U.S. Patent 3l864,471 discloses a dentifrice
composition containing a monoEluorophosphate and a polishing
agent containing alkaline earth metal carbonate and insoluble
alkali metal phosphate, alumina or mixture thereof, to minimize
corrosion in unlined aluminum containers.
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SUMMARY OF THE INVENTION
.
It is accordingly an object of the present invention to
overcome or otherwise mitigate these problems of the prior art.
It is a further object of this invention to provide a
novel toothpaste composition which will not stain or otherwise
corrode unlined tubes, a novel abrasive for use in such toothpastes,
and provide a method for the preparation and packaging of a
toothpaste composition in unlined tubes which will not cause
corrosion and staining problems on the interior of the tube.
A still further object of the invention is to provide a
non-corrosive therapeutic toothpaste composition which contains
a controlled amount of alkaline earth metal ion so that the
resulting composition can be placed in and marketed in unlined
aluminum tubes.
Other objects and advantages of the present invention
will become apparent as the description thereof proceeds.
In satisfaction of the foregoing objects and advantages
there is provided by this invention an abrasive composition use-
ful for incorporation into a therapeutic toothpaste composition
and for preventing fluoride-caused corrosion and staining of an
unlined aluminum tube containing said toothpaste composition,
said abrasive composition consisting essentially of a silica
which has been treated with a water soluble alkaline earth metal
compound so as to have present therein from about 168-7000 ppm of
the alkaline earth metal, said silica functioning as a carrier
for the alkaline earth metal and having an RDA value of between
200-400.
There is further provided by this invention a therapeutic
dentifrice composition compatible with the interior surface of an
unlined aluminum tube containing said composition, said dentifri`ce
.. . . . .
~L~LID2S6;~
composition comprising a fluoride therapeutic agent, a solid
phase, a liquid phase, and a fluoride corrosion and staining
preventing amount of an alkaline earth metal ion; said amount
being about 0.005 to 0.20% by weight, and said metal ion bein~
provided in an abrasive composition, said abrasive composition
being formed by treating a silica suitable for use in a tooth-
paste composition and having an RDA value of between 200-400 with
a water soluble alkaline earth metal compound.
As pointed out above, since the introduction of tilerapeutic-
containing dentifrice compositions, it has not been possible
to produce a commercially usable product which could be
packaged in unlined aluminum tubes because of the incom~ati-
bility problems between the aluminum surface of the tube and
the other components of the dentifrice, particularly the fluorides.
While substantial work has been carried out in an effort to
overcome this problem as indicated by the prior art discussed
above, probl~em~ in this area still persist. The present
invention overaomes problems of this type in a commercially
viable manne~ and provides a fluoride-containing dentifrice
or toothpaste composition which can be packaged and sold
in unlined aluminum tubes.
According to the present invention, it has been discovered
that the problem of corrosion of unlined aluminum tubes when
formulated with a therapeutic dentifrice composition can be
overcome by incorporation within the toothpaste composition
of a controlled amount of an alkaline earth metal. The
alkaline earth metal with which this invention is primarily
concerned is especially calcium, but there also may be used
magnesium or strontium. Calcium is preferred because of its
5~3
ready availability, inexpensiveness and ease of incorporation
into the dentifrice. The metal may be incorporated into the
dentifrice or toothpaste mixture in any substantially water
soluble form such as the nitrate, oxide, hydroxide or chloride.
The most preferred materials for incorporation into the
therapeutic dentifrice compositions of this invention include
calcium nitrate, calcium oxide, calcium hydroxide, and
calcium chloride. It should also be noted however, that
organic salts such as calcium acetate, calcium formate and the
like may also be used. Corresponding strontium and magnesium
salts may also be used. The only limitations to be placed
on the alkaline earth metal salt are that it be substantially
soluble, not cause any problems of safety in the compositions,
and remain available to combat corrosion.
There are of course dentifrice and other toothpaste
compositions known in the art which contain calcium salts in
substantial amounts~ a8 taught for example in U.S. Patent
3,864~71 Which contain9 40-S0~ of calcium carbonate and
U.S. Patent 3,624,199 which contains 20-75% calcium carbonate.
However, calcium carbonate is generally insoluble, and is
not effective to inhibit corrosion of the tube. Therefore,
an important aspect of the present invention resides in the
carefully controlled amount of water-soluble alkaline earth
ion which is incorporated into the toothpaste composition.
According to the present invention, the controlled amount of
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alkaline earth metal ion which is present must be sufficientto be effective and available to prevent corrosion but yet
insufficient to stoichiometrically interfere with fluoride
availability in the toothpaste. According to the present
invention, it has been found that the amount of alkaline
earth metal which must be present to prevent corrosion is
at least about 50 parts per million~or 0.005 weight percent,
and not more than about 2000 parts per million, or o.2 weight
percent, should be present to avoid interference with fluoride
availability. Therefore, the amount of alkaline earth metal
which should be present should range from about 50-2000 parts
per million or 0.005 to 0.2 weight percent based on the
toothpaste.
As pointed out above, the alkaline earth metal ion
may be incorporated into the toothpaste as any water soluble
salt. However, it is also within the scope of the present
invention to supply the alkaline earth metal ion in combination
with silica and silicate type abrasive and/or polishing agents.
According to one aspect o this embodiment, a controlled structure,
amorphous precipitated silica may be incorporated into the
therapeutic composition in sufficient amounts to supply the
necessary alkaline earth metal, such as calcium iOIl, to overcome
the problems of corrosion and staining. These dentifrice grade
controlled structure precipitated silicas contain calcium ions
on the silica surface of the precipitated silica abrasive,
polishing agent or thickening agent.
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The dentifrice grade controlled structure precipitated
silicas or silicon dioxides referred to above are novel products
available from the J. M. Huber Corporation and are silicon
dioxide products of the type described for example in my U.S.
Patents 3,9~0,586 and 3,928,541 which have been treated with an
alkaline earth metal salt to provide the alkaline earth metal
ions in the composition. The products described in these
patents are precipitated silicic acid or silicon dioxide pigments
which are prepared by the acidulation of an alkali metal silicate
such as sodium silicate and an acid such as sulfuric acid, in the
presence of a salt or electrolyte such as sodium sulfate. The
precipitated silicas resulting from the reaction wherein the
sulfate is a necessary reactant in the process may be described
as sulfate liquor products. After preparation of the precipitated
lS silica in wet cake form,and washing, it is then reslurried in
water and treated with a soluble alkaline earth metal salt such
as calcium hydroxide, calcium oxide, calcium nitrate, or calcium
chloride, in sufficient amounts to incorporate the necessary amount
of alkaline earth metal ions directly into the silica. The
reaction of silica with alkaline earth metal is conducted at
ambient temperature and with agitation. The amount of alkaline
earth metal ions introduced will be sufficient to provide the
required amount of alkaline earth metal ions in the toothpaste
but is correlated with any desired amount of alkaline earth metal
ions incorporated directly into the toothpaste composition.
It will be understood therefore that the amorphous
silica material is pretreated with the critical level of alkaline
earth metal material and then incorporated into the toothpaste
composition in the requisite amounts as desired. These silica
compositions provide good cleaning properties at RD~ values of
between 200 400. (RDA - Grabbenstetter et al, Jour. of Dental
Research, 37, 1060, 1958).
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The precipitated silicon dioxides of the present
invention are preferably prepared by charging a 3-15 weight percent
aqueous solution of alkali metal sulfate, preferably sodium
sulfate, to a reactor and adding a solution of an alkali meatl
S silicate solution, preferably a sodium silicate solution, to
the reactor to achieve a pH of about 8-10.4. This results in
pre-polymerization of the alkali metal silicate. The aqueous
sodium silicate solution should have a silicate concentration range
of about 10-25 weight percent, and more preferably 18 to 22
weight percent, and a composition of Na2O 2.6 SiO2 for best results.
The aqueous solution is then raised to a temperature of about 66
to 83C. (150 to 180~F.) and with continuous agitation the solution
is acidulated by the addition of an aqueous solution of a mineral
acid having a concentration of about 10-25 weight percent at
a substantially constant pH in the range of about 8.0 to 10.4.
Preferably the mineral acid and alkali metal silicate are added
simultaneously as described in my U.S. Patent No. 3,960,586. For
purposes of preparation of the basic precipitated silica or
silicon dioxide, attention is drawn to my prior U.S. Patents
3,960,586 and 3,928,541. The mineral acid is preferably
sulfuric acid as sulfuric acid provides best results
but as known in the art as in my prior U.S. Patent
3,960,586, other acidulation agents such as nitric
acid, phosphoric acid, hydrochloric acid, carbonic acid and
the like may also be employed. The time period over which
the alkali metal silicate and/or sulfuric acid are added to the
reactor can be predetermined and is generally based on the volume
of the reactor and the difficulties in control on the volume of
the reactor and the difficulties in control of the temperature
and a~itation. After completion of the additions, the acidulation
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33256~
acid is continued to be added until the pH of the slurry falls
below about 6.0 and preferably in the range of about 4.8-5Ø
The resulting slurry is the precipitated silicon dioxide contained
in the reaction medium.
After the pH of below 6.0 is obtained, the slurry is
then heated for a digestion period of 10 to 30 minutes at a
temperature of 10 to 30C. above the reaction temperature and
the reaction pH again adjusted as necessary. The resulting slurry
is then filtered and washed with additional water to remove any
reaction by-product such as sodium sulfate which may be contained
in the silicon dioxide product.
In the process of the present invention, at the point
of filtration and washing of the silicon dioxide wet ca]ce, the
material is then subjected to treatment with alkaline earth metal
ions to produce the new abrasive products of the present invention.
~n accordance with the process of the present invention, the wet
wash filter cake is then reslurried in its own water or with the
addition of fresh water at ambient temperature with agitation.
While under agitation, this slurry i8 then treated with sufficient
alkaline earth metal ions and preferably calcium ions, in the form
of substantially soluble salt to provide sufficient alkaline earth
metal ions corresponding to provide about50 to 2000 parts per
million, intimately associated with the silicon dioxide, this amount
being based on 100 parts of dentifrice. The amount of alkaline
earth metal ions added is based on the total weight of the dry
product contained in the wet cake form, that is recoverable solid.
Since the amount of abrasive may vary in dentifrice compositions,
the amount of alkaline earth metal salt will also be varied.
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The alkaline earth metal ion added at this point is
preferably calcium ion because of its readily availability,
inexpensiveness and ease of incorporation into the silicon
dioxide. The calcium ions may be incorporated into the silicon
dioxide at this stage in any substantially water soluble form
such as the nitrate, oxide, hydroxide, or chloride, but lime
or calcium hydroxide is preferred. Food grade salts should be
used. By soluble salt is meant that any reasonably soluble
salt of calcium may be used since it is only necessary to
provide extremely small amounts of the calcium ions to the
mixture. Also, organic salts such as calcium acetate, calcium
formate, and the like may also be used. The corresponding
strontium and magnesium salts of the alkaline earth class may
also be used. The only limitations to be placed on the alkaline
earth metal salt to be added are that it be sufficiently water
soluble to provide the ions, not present any problems of safety
in the res~lting toothpaste aompositions, and be effective to
provide the neces9ary fluoride compatibility.
After treatment with the alkaline earth metal ion,
the cake slurry is then agitated vigorously for 10-20 minutes,
preferably lS minutes, to provide the effective level o alkaline
earth metal for treatment on the surface of the silicon dioxide
abrasive. The resulting product is then filtered, spray dried,
preferably at an inlet temperature of 483C. (900F.) and outlet
temperature of 122C. (250F.) as known in the art, and
subsequently milled to the desired degree of fineness.
.
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The precipitated amorphous silicas which are preferably
used in this embodiment may be characterized by the following
combinations of properties:
Oil Absorption-Rub-Out Method (cc/lOOg) = ~0-120
BET Surface Area tm /g) = 75-325
MSA Average Aggregate Size ~micron) = 1-10
Bulk Density (lbs./cu.ft.) - 10-30
A preferred range of properties includes: a pack density of
about 0.24 to 0.51 grams per milliliter, an oil absorption of
about 75-95 ccs/100 grams, a BET surface area of about 100-250
m g, and a percent loss on ignition of about 4-6%.
It is also to be understood however, that the invention
includes other types of silica polishing agents including Xerogels
as described in U.S. Patent 3,538,230. Commercially available
Xerogels such as Syloid~63,manufactured by Davison Division of
W.R. Grace & Co.,can beutilized when incorporated with controlled
amounts of calcium ion or alkaline earth metal ions or pretreated
with calcium ion or alkaline earth metal ions, as described herein.
It is also to be understood that sodium aluminosilicate polishing
agents can be formulated in therapeutic compositions according
to this invention when the sodium aluminosilicate materials are
combined with the critical amounts o alkaline earth metal as
described herein.
As known in the art, a dentifrice may contain; e.g.,
humectant materials and binders to give the dentifrice a smooth
texture and good flowability. The specific formulations of
toothpastes are well known in the art and are disclosed for
example in U.S. Patents 2,994,642 and 2,538,230 and numerous
publications. A further detailed disclosure of dentifrice
formulations is given in U.S. Patent 3,726,961.
In this regard, dentifrice formulations have been
produced, ranging from liquids and powders to the highly popular
pastes or dental creams. Dental creams are the more difficult to
compound successfully in that they require careful balancing of
polishing agent, humectant, water, binder, preservatives,
detergents, flavoring, sweeteners, and therapeutic agents to
produce a smooth homogeneous paste.
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563
Most dental cream ~ormulations use one of several
conventional phosphate materials as the polishing agent.
Examples of the phosphate polishing agents are dicalcium
phosphate, anhydrous dicalcium phosphate, tricalcium
phosphate, thermally converted dicalcium phosphate, and
insoluble sodium metaphosphate. The amount of phosphate
materials added to the dental formulations will range
between about 5 percent and 60 percent by weight.
The most widely used humectants in toothpaste are
glycerine and sorbitol. Propylene glycol is also used in
small amounts and to a very limited extent. The primary
function of humectant as part of the liquid phase is to
retain moisture which provides good texture and maintains
an attractive glossy appearance when the paste is exposed
lS to air.
The binder employed therein is to prevent separation
of the li~uid and solid phases. The most conventionally
used binders are the seaweed colloids and synthetic derivatives
of cellulose, specifically Carrageenan and sodium carboxy-
methyl cellulose. Others such as gums have been used.
Combinations of these binders have also been employed.
Since the natural and synthetic water dispersions of
organic blnders are subjected to microbial or mold attack,
a relatively small amount of preservatives is added to the
paste. Examples of preservatives used in the industry are
the esters of parahydroxyl benzoates.
The function of the detergents within the dental
formulation is to provide greater cleansing action due to
the lowering of the surface tension and the sudsing action
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563
in the mouth. Among detergents used are sodium N-lauryl
sarcosinate, sodium lauryl sulfate, sulfoculaurate, sodium
alkyl sulfoacetate, and sodium dioctyl sulfosuccinate.
Since too~hpaste flavoring probably represents the greatest
single factor in consumer acceptance, great care has been
employed in selecting balanced blends of different essential
oils. These are rarely, if ever, used alone. Combinations of
principal flavors are wintergreen, peppermint, and sassafras,
and are used with secondary oils such as pimento, clove and anise.
Saccharin and sodium cyclamate are widel~ used to improve
taste and enhance the flavor qualities of the toothpaste. The
synthetic sweeteners may be used in combination to obtain
optimum sweetness and absence of after-taste. Their desirable
properties are obtained at ver~ low concen~rations and conse-
quently they have negligible influence on the toothpaste
consistency.
Since water is such a common element, i.t is important in
obtaining stable toothpaste formulations co employ
substantially pure water therein. It is common practice
to demineralize the water that is employed.
It is also within the scope o~ the invention to provide
the proper amount of alkaline earth metal within the dentif~ice
composition by pretreating the water with the calcium or
alkaline earth metal so that the water used can serve as
the alkaline earth metal source.
The invention is operable with respect to any of the
therapeutic agents now being used in therapeutic dentifrice
compositions including the alkali metal fluorides such as
sodium fluoride, sodium monofluorophosphate, stannous fluoride,
and the like, all of which are well known.
In general, such dentifrice compositions will normally
contain about 5-50 wt% of polishing agent, up to about
1 wt% of ~luoride-containing therapeutic agent, about
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30-40 wt. % deionized water, and the remainder being liquid
phase carrier materials such as glycerin, sorbitol and the
like. As indicated above, according to the present invention,
the composition will also contain from 0.005 up to 0.20
S weiqht percent of alkaline earth metal ion, preferably calcïum
ion, based on the toothpaste composition. It has been
found that this amount of alkaline earth metal is su~ficient
to overcome problems with staining and corrosion of unlined
aluminum tubes, but is insufficient to interfere with the
fluoride availability in the paste and thus not interfere
with the therapeutic action of the dentifrice composition.
With respect to incorporation of the controlled
amount of alkaline earth metal in the compositions of the
present invention, it is to be noted that in Degussa Technical
Bulletin No. 49, there is a disclosure of an "Aerosi ~200"
polishing agent for use in chalk toothpastes, and it is
pointed out on page 8 of this Bulletin tha- in toothpastes
containing the cheaper polishing agent,chalk, the use of
"Aerosi ~ 200" is worthwhile to the extent that the less
expensive unlacquered aluminum tubes can be used since
corrosion protection for unlacquered aluminum tubes is by
ormation of minute quantities of insoluble calcium silicate
from this composition. A minimum of 1% of "Aerosi ~200" is
required. However at page 8 of the same Bulletin, it is
stated that even with the use of "Aerosil ~ it is not possible
to attain effective corrosion protection for nontreated
aluminum tubes when the toothpaste compositions contain
fluorine in the form of monofluorosodium phosphate. However,
this reference does teach on page 8, that when 3-5 weight
percent of Light Hydrated Alumina W-16 is incorporated into
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the fluoride-containing toothpaste, corrosion protection can
be obtained. Contrary to tlle teachings of this Technical
Bulletin, it has been discovered according to the present
invention that fluorine-containing toothpastes can be placed
in unlined aluminum tubes if there is placed therein a
controlled amount of alkaline earth metal ion.
In consideration of the incorporation of silica t~pe
products in the dentifrice composition of the present invention,
it will be understood that all silica products and raw materials
have incidental amounts of calcium present. For example, trade
publicatlons covering the Xerogels sold as Syloi ~63 indicate
the presence of 0.01~ calcium as calcium oxide. This corresponds
to .007% calcium or up to 70 parts per million in Syloi ~G3.
However, since only about up to 35 weight percent levels
of the silica products can be incorporated into toothpaste
compositions, this indicates that inherently, the resulting
dentifrices can contain only .0035 of calcium oxide or 25 ppm
o calcium, an insufficient amount for corrosion protection.
It will also be noted that the precipitated silicas of
J. M. Huber Corporation as described above, have a tendency
to pic~-up or react with calcium ions which make these
products extremely attractive for combination with the correct
amount of calcium ions and incorporation into toothpastes
since the silicas also provide excellent abrasion properties
for toothpaste compositions.
The silica abrasives described herein are used at
loadings of about 15-30 wt % in the dentifrice. Therefore they
should contain a minimum of 168 ppm calcium at 30 wt % and
336 ppm at 15 wt % to provide minimum amounts of calcium.
However, they can also contain u~6to about 7000 ppm or more.
Z563
The following specific examples are further
illustrative of the nature of the present invention, but it is
to be understood that the invention is not limited thereto.
The compositions are prepared in the conventional manner and
all amounts of the various ingredients are by weight unless
otherwise specified. In the following examples and throughout
the specification parts are by weight unless otherwise indicated.
EXAMPLES
In the following examples t~i~ -toothpaste compositions
were prepared and compared with comme~-~ial products or controls.
In evaluating the toothpaste composi;:Lons, a chart was used
to rate the interior tube wall to determine the presence or
absence of staining and corrosion. As basis for the chart,
each composition was prepared and then aged at 49C. for
nine weeks. The percentage of soluble fluoride ion and tube
compatibility data were determined periodically during the
nine-week storage stability period. In this examination, each
three weeks under the aging conditi~ns (49C.) corresponds
to about one y~ar aging at room temperature. During the studies,
the unlined tubes containing the compositions were opened
periodically and examined for any staining/corrosion on the
tube interior wall. The followinglegend was used for rating
the tube properties of the compositions:
Rating Tube Interior Wall
No air on wall, no discoloration on wall
8-9 No air on wall, light gray stain on wall
6-7 Air on wall, light gray stain on wall
4-5 Air on wall, gray stain on wall
2-3 Air on wall, dark gray stain on wall
1 Air on wall, black stain with pitting of wall
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In all of the following examples, the alkaline earth metal
was calcium and was added as soluble calcium nitrate to
provide the amount of calcium indicated in each composition.
EXAMPLES 1-4
Dent-~frice Compositions in Which Calci m Was Added to the Toothpaste
The following dentifrice compositions were prepared with
a low structure silica polishing agent and a known level of
calcium was added to the composition to provide tube compati-
bility properties.
Examples 1-4
Composition
1 2 3 4
Sodium monofluorophosphate0.7-6 0.760.16 0.76
Low Structure silica30.00*29.97029.94129.587
Calcium as water soluble
Ca(N3)2 4H2O** 0.00 0.0295 0.0590.413
Glycerine 23.00 23.00 23.0023.00
Sodium carboxymethyl-
cellulose 1.30 1.30 1.301.30
Hydrated alumina 1.00 1.00 1.001.00
Sodium lauryl sulfate 2.00 2,002.00 2.00
Sodium benzoate 0.50 0.5~ 0.500.50
Sodium Sacoharin 0.20 0.29 0.200.20
Flavor 0.90 0.94 0.900.90
~r, Water ~deionized) ~alance ~alance Balance Balance
.. . .
'~'otal 100.00 100.00 100.00 100.00
* low structure silica containing 5 ppm calcium
** The conversion factor for calcium nitrate.4H O to
calcium is 5.9. The molecular weight of Ca(NO ~ ~ 4H~O
is 236. The atomic weight of calcium is 40. ~herefore
236 parts of calcium nitrate . 4H2O provide 40 parts of
calcium ion, or 236/40 or 5.9 parts of calcium nitrate 4H2O,
which corresponds to one part of calcium.
In compositions 2, 3, and 4, calcium nitrate 4l-l2O was
added in the dentifrice composition which corresponds to
calcium level of 0.0295/5.9 or 50 ppm (0.005%3; 100 ppm (0.01~)
and 700 ppm (0.07%), respectively. The tube compatibility
data for these Examples are set forth in following Table 1.
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TABLE 1
Rating of Tube Properties - 49C Aging Study
Weeks
Composition O 1 3 6 9
1 10 4 3 3
2 10 10 1010 10
3 10 10 1010 10
4 10 10 1010 10
It is clear from above data that composition 1 was
unacceptable in tube compatibility properties becaus~ it did
not contain the minimum critical level of calcium in the
therapeutic dentifrice composition.
EXAMPLES 5-8
The following dentifrice compositions were prepared
wherein the content of sodium monofluorophosphate in each is
equivalent to 0.1% fluoride ion.
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Composition Parts
_ _ .
Sodium monofluorophosphate 0.76 0.76 0.76 0.76
Low Structure silica 30.00~A) 30.00(B) 30.00(c) 30.00(D)
Glycerine 23.00 23.00 23.00 23.00
Sodium carboxymethyl-
cellulose 1.30 1.30 1.30 1.30
Hydrated alumina 1.00 1.00 1.00 1.00
Sodium lauryl sulfate 2.00 2.00 2.00 2.00
Sodium benzoate 0.50 0.50 0.50 0.50
Sodium saccharin 0.20 0.20 0.20 0.20
Flavor 0.90 0.90 0.90 0.90
Water (deionized) 40.34 40.34 40.34 40.34
Total 100.00 100.00 100.00 100.00
(A) low structure silica of composition 5 contained 5 ppm
calcium
(B) low structure silica of composition 6 contained 168 ppm
calcium
(C) low structure silica of composition 7 contained 406 ppm
calcium
(D) low structure silica of composition 8 contained 688 ppm
calcium
The low structure silicas employed in Examples 5, 6, 7
and 8 were characterized by the following combination of properties:
Oil Absorption - Rub-Out Method (cc/100 mg) = 80-120
BET Surface Area (m2/g) = 75-325
MSA Averagé Aggregate Size (microns) = 1-10
~ulk Density ~pounds/cu.ft.) = 10-30
The calcium treated low structure silicas of compositions
5, 6, 7 and 8 were prepared by the following procedure:
Dry sodium sulfate was added to 10.0 gallons of water
in a 200 gallon reactor so that the sodium sulfate concentration
in the reaction medium was 10%. The pH of the reaction medium
was then adjusted to 9.0 by the addition of sodium silicate.
The reaction temperature was 65C. (150F.~. The sodium silicate
solution had an SiO2~ Na2O mole ratio of 2.5 and a concentration
of 2,0 pounds per gallon. Sodium silicate was added to the
reaction medium for 4 minutes. At this point the sodium
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silicate addition was stopped and sulfuric acid of 11.4~
concentration was added to the reaction medium until the pH
of 9.0 was reached. At this point the sodium silicate solution
and the sulfuric acid solution was added simultaneously for a
period of 35 minutes. At the end of the 35 minute period of
silicate addition, the silicate was discontinued and the acid
addition was continued until a slurry pH of 5.5 was obtained.
The batch was digested at 77C. (170F.) for 20 minutes and
the resulting wet cake recovered and washed.
The wet cake was then divided into four separate
portions and treated by the following procedure.
Each batch of wet wash filter cake was then reslurried
without water addition at ambient temperature with agitation.
While under agitation, the slurry was treated with sufficient
Codex grade ~U.S. purity food grade) hydrated lime (calcium
hydroxide) to provide the amount of calcium ion treatment
described in compositions 5, 6, 7 and 8. The amount of
calcium hydroxide was based on the weight of dry recoverable
solid product in the wet cake form. ~fter treat~ent with the
calcium ion, the cake slurry was agitated vigorously for 15 minutes
to provide the effective level of calcium ion treatment on the
surface of the silicon dioxide abrasive. Each resulting product
is then spray dried at an inlet temperature of 483C. and outlet
temperature of 122C. milled and characterized.
Compositions 5, 6, 7 and 8 were aged at 49C. for nine
weeks and tube compatibility data were determined periodically
during the nine-week storage stability period. The results for
tube compatibility properties are li~ted below in Table 2.
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TABLE 2
Rating of Tube Properties - 49C Aging Study
Weeks
Composition _ 1 3 6 9_ _ _
4 3 3
6 10 10 10 10 10
7 10 10 10 10 10
8 10 10 10 10 10
It will be noted from Table 2 that dentifrice composition
5 caused a severe degree of black stain and pitting on the
tube wall after nine weeks of aging study. Compositions 6,
7 and 8 were stable and showed excellent tube compatibility
prope~ties. Thus, it is very clear that when a silica polislling
agent contains a minimum critical level of calcium, it does
not corrode the unlined aluminum tubes.
EX~PLES 9-11
Stabilization of Xerogel Therapeutic Dentifrices with Calcium
Therapeutic dentifrices were prepared with xerogel
polishing agents. All compositions contained a known level of
calcium ions ~added as water soluble calcium nitrate) except
composition 9. The compositions were prepared in the conventional
manner and packaged in unlined aluminum tubes. ~11 amounts of
the varlous ingredients were by weight unless otherwise specified.
The following dentifrice compositions were prepared.
The Content of sodium monofluorophosphate in each was equivalent
to 0.1% fluoride ion.
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. .
.
i3
Composition Parts
9 10 11
Glycerine (99.5% solution) 22.00 22.00 22.00
Sodium benzoate 0.50 0.50 0.50
Sodium saccharin 0.20 0.20 0.20
CMC - 7 MF 1.00 1.00 1.00
Sodium monofluorophosphate 0.76 0.76 0.76
Water (deionized) 36.54 36.54 36.54
Xerogel (Syloid~Y63)35.00 34.82 34.70
~Iydrated alumina 1.00 1.00 1.00
2 0.50 0.50 0.50
Sodium lauryl sulfate1.50 1.50 1.50
Calcium nitrate . 4l~2O*0.00 0.18 0.30
Flavor 1.00 1.00 1.00
* 0.18% and 0.30~ calcium nitrate 4~20 in compositions
10 and 11 correspond to 0.18/5.9 or 0.03~ calcium (300 ppm
calcium) and 0.30/5.9 or 0.05% calcium (500 ppm calcium)
It will be noted that the composition of Example 9 did
not contain any calcium. The tube properties were then
determined when the dentifrices were aged at 49C for nine
weeks and were rated at intervals of 1, 3, 6, and 9 weeks.
The following Table 3 shows the degree oE corrosion or staining
of the unlined aluminum tubes.
TA~LE 3
Tube Compatibility Properties - 49C Aging Study
Weeks
Composition 0 1 3 6 9
9 10 7 6 6 5
10 10 10 10 10
11 10 10 10 10 10
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11`~;Z 563
From the data in Table 3 it is clear that the
compositions of Examples 10 and 11 exhibit excellent tube
compatibility properties. Note that rating of 10 means no
discoloration of the unlined tube container. Since composition
9 did not contain the critical level of calcium, the tube
compatibility properties were found to be unacceptable after
nine weeks storage at 49C~
According to the suppliers bulletin, the Xerogel,
Syloid 63, has the following properties:
Loss on ignition 6.5
5~ slurry pH 4.1
% SiO2 ignited basis 99.5
Particle size, microns 9.0
Surface area, m2/g625
Oil absorption, #/100 lb 60
Bulk density, pounds/cu. ft. 29
In addition to above properties, Syloid 63 has the
following chemical composition (from supplier's bulletin):
Chemical Analysis (dry basis)
Aluminum as A12O3 0.04
Titanium as Tio2 0.03
Calcium as CaO 0.01
Sodium as Na2O 0.02
Zirconium as ZrO2 0.01
Trace element ~oxides) 0.02
EXAMPLE 12
Effect of Calcium on Commercial Toothpastes
"Aim'~Yclear-gel therapeutic toothpaste is packaged
in a lined container to prevent corrosion and staining of tube
interior wall.
"Colgate~Dental Cream" (CDC) is also packaged in a
lined container to avoid the corrosion and staining of the tube
interior wall.
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. . : .
63
To check the effectiveness of calcium addition in solving
the tube compatibility problem, both "Aim~ and "CDC" were
purchased from the supermarket and each paste was divided
into three parts.
S "Aim ~toothpaste was divided in parts A, B, and C.
Part A was packaged in an unlined aluminum tube without any
addition of calcium to the toothpaste. Parts B and C were
mixed with a known level oE calcium and then packaged in
unlined aluminum tubes.
"CDC" (Colgate~Dental Cream) was also divided into
three parts D, E, andF. Part D was packaged in an unlined
aluminum tube without the addition of any calcium. To parts
E and F, a known level of calcium was added. The data
obtained with "Aim ~and "CDC" compositior,s packaged in unlined
containers are listed in Table 6 and the compositions for
each are as follows:
EXAMPLE 12
Composition % Calcium(3)C%ommercial
A 0.00100.00 ~1)
B 0.1099.41 (1)
C 0.1699.1f, (1)
D 0.00100.00 (2)
E 0.10gg.LIl (2)
F 0.16gg.lG (2)
(1) Ai ~toothpaste, purchased from supermarket
(2) Colgate~Dental Cream, purchased from supermarket
(3) Added as Ca(NO3)2 4 H2O
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2~63
TABL~ 4
Tube Compatibility Properties - 49C A~ing Study
Weeks
Composition 1 3 6 9
A 5 4 3
B 10 10 10 10
C 10 10 10 10
D 5 5 4 2
E 10 10 10 10
F 10 10 10 10
Compositions B, C, E and F have excellent tube compatibility
properties when compared with compositions A and D. The addition
of the calcium thus helped stabilize these therapeutic dentifrice
compositions.
EXAMPLES 13-17
The following dentifrice compositions were prepared to
illustrate the use of sodium aluminosilicates (SAS) as polishing
agents, The composition of Example 13 was used as a control
in which no calcium was added. Known amounts of calcium were
added to the compositions of Examples 13, 15, 16 and 17. The
compositions were as follows:
Parts
Composition 13 14 15 16 17
Glycerine (99.5~)22.0022.00 26.0025.00 30.00
Sodium benzoate 0.50 0.50 0.50 0.50 0.50
Sodium saccharin0.20 0.20 0.20 0.20 0.20
CMC - 7 MF 1.00 1.00 1.00 1.00 1.00
Sodium monofluoro-
phosphate 0.76 0.76 0.76 0.76 0.76
Calcium nitrate 4ll2O*0.00 0.20 0.20 0.20 0.24
Deionized water36.54 36.34 39.5438.54 43.30
SAS Polishing agent35.00(A) 35.00(A)27.80(B)29.80~C)20.00(D)
Hydrated alumina l.Q0 1.00 1.00 1.00 1.00
l'iO2 0.50 0.50 0.50 0.50 0.50
Sodium lauryl sulfate 1.50 1.50 1.50 1.50 1.50
Flavor 1.00 1.00 1.00 1.00 1.00
* Note that in compositions 14, 15 ~nd l6, 0.2% C~ (N03) 2 4H20
corresponds to 0.03~ calcium ion and 0.24~ Ca (N03) 2- 4l12O in
composition 17 corresponds to 0.04~ calcium ion.
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,~ , .,, - , . . .
;2563
(A) The SAS product used in compositions 13 and 14 has a
SiO2/Al203 ratio of 11.0
~) The SAS product used in composition 15 has a SiO2/~1203
ratio of 2.5
(C) The SAS product used in composition 16 has a SiO2/Al20
ratio of 130 3
(D) The SAS product used in composition 17 has a SiO2/Al203
ratio of 400
The preferred sodium aluminosilicates (SAS) have the following
molar chemical composition:
Na20 Y Al203 z SiO2 w ~2
wherein x denotes the moles of Na20
y denotes the moles of Al203
z denotes the moles of SiO2
w denotes the moles of water
When y is fixed at l, the value of z corresponds to the silica/
alumina molar ratio of SAS. The low structure SAS abrasives
and polishing agents have a si.lica/alumino ratio or z values
of 2.5 to 400.
The properties of SAS polishing agents are:
Oil ~bsorption, Rub-Out Method (cc/lOOg) = 75 - 125
~ET Surface Area (m2/g) - 50 - 300
MSA Average Aggregate Size (microns) = l - lO
Bulk Density (pounds/cu.ft.) = 12 - 35
Compositions 13 through 17 were aged at 49C for nine
weeks and the tube compatibility properties were evaluated
at intervals of 1, 3, 6, and 9 weeks and the results are
shown in the following Table 5.
~ '' ~ ' , -
Z5~3
TABLE 5
Tube Compatibility Properties, 49C.
Weeks
Composition 1 3 6 9
_ = _
13
14 10 10 10 10
10 10
16 10 10 10 10
17 10 10 10 10
Note that compositions 14 through 17 have excellent
tube compatibility properties.
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