Note: Descriptions are shown in the official language in which they were submitted.
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FLUORIDE COMPATIBLE CALCIUM CARBONATE
FIELD OF THE INVENTION
This invention relates to ingestable calcium carbonate compositions, a method
for
its preparation, and the use of such in food products, supplements, mouth
washes,
dentifrices, gels, chewable tablets and the like.
More particularly, this invention relates to treated calcium carbonate
materials
1o that resolves the matter of taste and interaction with other components.
One particular
problem addressed is that of chalky taste in food products and dietary
supplements.
Another problem is food system compatibility and another is the problem of
fluoride
stability in dental hygiene compositions.
15 BACKGROUND OF THE INVENTION
Calcium carbonate is used in food products and dietary supplements as well as
personal care products, which are used in the mouth. Such use can be in
toothpaste and
powders, dietary or nutritional supplements, antacids, food products, such as
breakfast
2o and snack foods, and the like. The benefits of such use can involve the
uptake of calcium
into the body system for use elsewhere and for the physical properties of the
calcium
carbonate in the oral cavity, such as in dental abrasives and carriers.
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When calcium carbonate is present in the oral cavity as a component of such
materials, the user can experience the unfavorable taste property of
chalkiness. Such taste
experience may be affected by the physical character of the calcium carbonate
material,
such as size and surface property. Another factor may be the chemical property
such as
ionization and the like.
Calcium carbonate as a cleaning abrasive is a commonly used component in
toothpaste and tooth powders. Another component in toothpaste and tooth
powders can
be fluoride to enhance enamel protection. Calcium carbonate can react with
fluoride to
1o form calcium fluoride (CaFz). When this reaction occurs, fluoride is
unavailable to
interact with teeth to provide protection. This interaction may occur during
the use of the
dental hygiene process or during storage over time. In either event, such
reaction
decreases the effectiveness of the fluoride treatment and is not desirable.
~ 5 European Patent Application No. 0 219 483 discloses a treated calcium
carbonate
abrasive comprising pulverized calcium carbonate in a liquid dispersion with
an alkali
metal pyrophosphate to produce a pyrophosphate derivative selected from the
group
consisting of calcium pyrophosphate, calcium alkali metal pyrophosphate, and
mixtures
thereof to chemisorb on the surface of the calcium carbonate particles.
U.S. Pat. No. 4,357,318 discloses a dentifrice comprising a water soluble
monofluorophosphate salt as a source of soluble fluoride in a therapeutically
effective
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anti-caries concentration, an effective abrasive amount of calcium carbonate
and a dibasic
alkali metal phosphate, said dentifrice being devoid of benzyl alcohol.
U.S. Pat. No. 3, 930, 305 discloses a dental cream containing an abrasive
system
comprising sodium bicarbonate in a vehicle containing water and sufficient
viscous water
miscible polyol humectant or mixtures thereof and a sufficient amount of
gelling or
thickening agent to impart to the dental cream the pasty consistency, body and
the non
tacky nature which is characteristic of conventional dental creams or
toothpastes, and a
water-insoluble dental abrasive material compatible with said bicarbonate in
the dental
to cream, said sodium bicarbonate being primarily in the undissolved solid
state, said dental
cream having a granular textured appearance comprising dispersed non-
crystalline
appearing granulate of macroscopic crystalline bicarbonate granules in an
otherwise
smooth continuous matrix.
t 5 U.S. Pat. No. 5,476,647 discloses a substantially phosphate-free two
component
system for increased deposition of fluoride onto and into dental tissue,
comprising a first
component of a soluble calcium source, a soluble calcium complexing agent and
a buffer
and a second component containing a fluoride compound and a buffer. When the
two
components are combined, there results a precipitation of calcium fluoride
gradually and
2o continuously over the course of about 10 seconds to about 4 minutes.
U.S. Pat. No. 4,420,312 discloses a method for the production of an abrasive
composition comprising a precipitated amorphous silicon dioxide. The abrasive
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composition, when incorporated into toothpaste compositions containing a
fluoride
therapeutic agent, provides a toothpaste composition which exhibits minimal
loss of
soluble fluoride upon storage at normal temperatures.
U.S. Pat. No. 5,939,051 discloses a dentifrice composition, comprising an
orally
acceptable dentifrice vehicle and a silica hydrogel.
U.5. Pat. No. 5,891,448 discloses a two-component system for delayed sustained
precipitation of calcium fluoride onto and into dental tissue comprising a
first component
1o containing a soluble calcium source, with no more than approximately ten
percent of the
calcium in complexed form; a second component containing a soluble fluoride
compound; and a calcium fluoride inhibitor present in either or both of
components. The
second component is isolated from the reaction with the first component during
storage
and prior to use. When the two components are combined, the inhibitor produces
a delay
15 of at least about five seconds before significant formation of calcium
fluoride occurs.
The level of phosphate in the system is less than the concentration needed for
significant
precipitation of hydroxyapatite.
U.5. Pat. No. 5,723,107 discloses a method for fluoridating teeth utilizing a
semi-
2o solid, extrudable, two component dentrifice system. The steps include
preparing as a first
component a semi-solid, extrudable dentifrice composition containing a
fluoride ion
releasable hydrolyzable complex fluoride compound in an aqueous acidic vehicle
in
which the fluoride compound is stable, the vehicle being free of abrasive and
surfactant
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and containing xanthan gum as the major thickening agent and glycerin,
sorbitol or
mixtures thereof as the humectant, and as a second component, a semi-solid
extrudable
aqueous dentifrice composition containing a calcium ion releasable compound
and an
abrasive in an aqueous vehicle contains xanthan gum as the major thickening
agent and
glycerin, sorbitol or mixtures thereof as the humectant. The first and second
dentifrice
compounds are kept separate from the other until application to teeth
requiring
fluoridation. Then the first and second components are mixed together to
deposit calcium
fluoride therefrom on contact with a tooth surface.
U.S. Pat. No. 5,145,668 discloses a method for fluoridating teeth with a
reactive,
multi-component composition. There are mixed a first component comprising
calcium
chloride together with a second component comprising sodium fluorosilicate, an
acetate
salt, and a sufficient quantity of soluble, non-toxic phosphorous salt to
maintain the
phosphorous concentration at a desired level. The sodium fluorosilicate of the
reactive
t 5 multi-component composition is hydrolyzed, and calcium fluoride is
precipitated from
the reactive mufti-component composition. The reactive mufti-component
composition is
applied to tooth surfaces for a period of time ranging from about 10 seconds
to about 4
minutes.
20 There remains the need to provide calcium carbonate particles in dental
hygiene
material, food products, antacids, dietary and nutritional supplements and the
like in a
form which has pleasant texture and palatable taste and without interfering
with other
beneficial components.
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An object of the present invention is to produce a calcium carbonate particle
that
is stable when used in an environment where fluoride ions are present (being
"stable"
means the calcium carbonate does not react significantly with the fluoride
ions or other
components).
Another object of the present invention is to provide a process for producing
calcium carbonate particles that are stable in an environment where fluoride
ions are
present. A further object of the present invention is to provide calcium
carbonate
particles that are stable when used in formulations where fluoride ions are
present. These
to and other objects of the present invention are more fully disclosed in the
detailed
description of the embodiments of the invention, which hereinafter follows.
SUMMARY OF THE INVENTION
S The present invention solves the problem of fluoride stability in toothpaste
when
calcium carbonate is used as an abrasive. In the present invention, calcium
carbonate is
treated with polymers and/or fatty acids making it fluoride compatible in
toothpaste
formulations.
20 The present invention is a fluoride compatible surface treated calcium
carbonate
dental abrasive that is effective when used in an environment where fluoride
compatibility is required.
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The present invention also solves the problem of chalkiness taste when
ingesting
material containing calcium carbonate particles by providing a calcium
carbonate particle
treated with polymers and/or fatty acids.
The present invention also provides enhanced shelf life to material using the
treated calcium carbonate particles in that such particles have reduced
reactivity with
other components.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a surface treated calcium carbonate particle
in
which the treatment is effective when the calcium carbonate particle is used
in an
environment where oral hygiene or ingestion is required. In particular, the
surface treated
calcium carbonate particular manifests beneficial taste characteristics or
interacts
t 5 beneficially with fluoride delivery systems by having reduced
characteristics to impact
fluoride stability in such systems.
One embodiment of the present invention is an ingestible material comprising
calcium carbonate particles, in which the calcium carbonate particles have
been
2o effectively treated with one or more agents selected from the group
consisting of fatty
acids and polysaccharides to reduce the sensation of chalkiness in said
ingested material
due to the presence of the calcium carbonate particles.
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In such use the ingestible material can be any material for consumption, such
as
food products, dietary and nutritional supplements, pharmaceuticals and the
like. The
presence of a calcium carbonate particle in such material can be for any of a
variety of
reasons. Such reasons include, without limitations, use of calcium carbonate
to provide
elemental, texture, filler or other purposes. Examples include, without
limitation,
processed foods, dietary and nutritional supplements, dental hygiene
compositions,
denture adhesives and the like.
Suitable calcium carbonate particles that may be surface treated by the
process of
1o the present invention include calcium carbonate particles having the
morphological forms
of aragonite, calcite, vaterite, amorphous and mixtures thereof. The calcium
carbonate
particles may also be synthetically produced precipitated calcium carbonate
(PCC) or
ground natural calcium carbonate. A preferred calcium carbonate particle has a
median
particle size of from about 0.5 to about 30 micrometers, preferably from about
1 to about
t s 15 micrometers. The specific surface area of calcium carbonate particle of
the present
invention is from about 0.5 meters square per gram to about 50 meters square
per gram.
A preferred specific surface area is from about 1 to about 10 meters square
per gram.
The specific surface area of the calcium carbonate is defined herein as the
area per unit
mass based on the sorption of nitrogen using the BET method.
Suitable surface treating agents include fatty acids and polysaccharides. The
fatty acids that are useful in the present invention have the general chemical
formula of
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CH3(CHZ)XCOzH, in which X ranges from about 2 to about 20, more preferably
from
about 8 to about 20. The fatty acid can be saturated or unsaturated.
Substitution is
permissible as long as the substitution does not substantially impact the
beneficial
properties of the present invention. Preferred fatty acids have the common
names of
lauric, palmitic, stearic, oleic, linoleic, and behenic. The treating level
for fatty acids
can range from about 0.01 percent to about 20 percent, preferably from about
0.05
percent to about 4 percent, based on the dry weight of calcium carbonate. The
treating
level can be affected by the surface area of the calcium carbonate in that as
the particle
size decreases, the treating level increases.
Preferred polysaccharides used in the present invention have nine or more
units
of monosaccharides (C6H,206) linked by glycosidic bonds and include, but are
not
limited to, gums, starches and mucilages. Other preferred polysaccharides that
are
useful in the present invention may be selected from the group consisting of
alginates,
Is xanthans, guar, carrageenan, gellan, and the like. The treating level for
polysaccharides
can range from about 0.05 percent to about 20 percent, preferably from about
0.05
percent to about 4 percent, based on the dry weight of calcium carbonate. The
treating
level is affected by the surface area of the calcium carbonate in that as the
particle size
decreases, the treating level increases generally.
One preferred polysaccharide form is starch. Starches that are useful in the
present invention may be selected from the group consisting of potato, corn,
tapioca,
carboxymethylcellulose, and the like. The treating level for starches can
range from
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about 0.05 percent to about 20 percent, preferably from about 0.05 percent to
about 4
percent, based on the dry weight of calcium carbonate. The treating level is
affected by
the surface area of the calcium carbonate. What this means, is that as the
calcium
carbonate particle size increases the treating level decreases. As the
particle size
decreases, the treating level increases.
Another preferred form of polysaccharides is mucilages. Mucilages that are
useful in the present invention may be selected from the group consisting of
agar,
tragacanth mucilage, yellow or white mustard mucilages and the like. The
treating level
1 o for mucilages can range from about 0.05 percent to about 20 percent,
preferably from
about 0.05 percent to about 4 percent, based on the dry weight of calcium
carbonate.
The treating level is affected by the surface area of the calcium carbonate.
What this
means, is that as the calcium carbonate particle size increases the treating
level
decreases. As the particle size decreases, the treating level increases.
In order to treat the calcium carbonate of the present invention with a fatty
acid
such as, for example, stearic acid, the fatty acids can be applied to calcium
carbonate by
dry coating. Dry coating is achieved by adding stearic acid to a dry calcium
carbonate
and mixing at a temperature from about 40 to about 200 degrees Celsius. The
2o temperature range should be sufficient enough to melt the fatty acid. The
resultant
calcium carbonate is treated with the fatty acid. The calcium carbonate of the
present
to
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invention so treated is particularly suitable for use in mouthwashes,
dentifrices, gels,
and chewable tablets where fluoride compatibility is desired.
An alternative method to dry coating is to wet coat the calcium carbonate. Wet
s coating is achieved by adding a solution or emulsion of fatty acids or
polysaccharides
including gums, starches and mucilages to a calcium carbonate slurry. The
calcium
carbonate slurry is prepared by synthesizing calcium carbonate in an aqueous
environment or adding water to a dried calcium carbonate powder.
Another alternative method for treating the calcium carbonate is by adding dry
calcium carbonate to a solution or emulsion of fatty acids or polysaccharides
including
gums, starches and mucilages. Still another alternative method for treating
the calcium
carbonate is by adding dry fatty acids or polysaccharides including gums,
starches and
mucilages to a calcium carbonate slurry.
is
The calcium carbonate abrasive treated in accordance with this invention
improves fluoride compatibility when incorporated into oral hygiene products
such as,
toothpaste, toothpowder, chewable gum, tablets, and other dentifrices.
2o The treated calcium carbonate abrasive of this invention can be used as the
sole
abrasive in the oral hygiene product or can be used in conjunction with other
dental
abrasives. Other suitable abrasives include water-insoluble sodium or
potassium
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metaphosphates, hydrated or anhydrous dicalcium phosphate, sodium bicarbonate,
calcium pyrophosphate, various forms of silica, zirconium, silicate and the
like.
The total amount of abrasives employed in oral hygiene products can range from
s less than 5 percent to more than 95 percent by weight of the dentifrice.
Generally,
toothpaste contains from 20 percent to 60 percent by weight of abrasive.
Abrasive
average particle size preferably ranges from about 2 microns to 20 microns.
In addition to the abrasive, toothpaste and tooth powder compositions
conventionally contain one of or a combination of a fluoride compound, sudsing
agents,
binders, humectants, flavoring agents, sweetening agents and water.
Suitable fluoride compounds can be any of the compounds previously mentioned
conventionally employed to provide available fluoride ion in the oral cavity.
Sodium
~ 5 monofluorophosphate, sodium fluoride and the like, have been employed with
good
results in toothpaste to promote dental hygiene. Good results can be achieved
employing an amount of fluoride compound to provide available fluoride ion in
the
range of 300 to 2000 ppm in the toothpaste, preferably 1000 ppm.
2o Suitable sudsing agents are generally anionic organic synthetic detergents
active
throughout a wide pH range. Representative of such sudsing agents used in the
range
of about 0.5 percent to 5 percent by weight of the composition are water-
soluble salts of
C,o C,8 alkyl sulfates, such as sodium lauryl sulfate; of sulfonated
monoglycerides of
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fatty acids, such as sodium monoglyceride sulfonates; of fatty acid amides of
taurine,
such as sodium N-methyl-N-palmitoyltauride; and of fatty acid esters of
isethionic acid,
and aliphatic acylamides, such as sodium N-lauroyl sarcosinate.
Suitable binders or thickening agents to provide the desired consistency are,
for
example, hydroxyethylcellulose, sodium carboxymethylcellulose, natural gums,
such as
gum karaya, gum arabic, gum tragacanth, colloidal silicates and finely divided
silica.
Generally, from 0.5 percent to 5 percent by weight of the composition can be
used.
Various humectants can be used, such as glycerine, sorbitol and other
to polyhydric alcohols.
Suitable flavoring agents include oil of wintergreen, oil of spearmint, oil of
peppermint, oil of clove, oil of sassafras and the like. Saccharin, aspartame,
dextrose,
levulose can be used as sweetening agents.
The following examples are being presented to further illustrate and support
the
novelty of the present invention. They are presented for illustrative purposes
only and
should in no way be used to limit the scope of the coverage, which is more
specifically
defined by the claims that are attached hereto.
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TEST METHODS AND PROCEDURES
XPS Surface Analysis
XPS (X-ray Photoelectron Spectroscopy) also referred to as ESCA (Electron
Spectroscopy for Chemical Analysis) is a surface sensitive technique with an
analysis
s depth of 5 - 50 Angstroms (A) (0.0005 - 0.005 microns). Samples are
bombarded with
X-rays causing electrons to be emitted. The electrons which evolve without
energy loss
originate from the top few monolayers. The spectrometer separates these
electrons
according to their kinetic energy. The energies of the photoelectrons depend
not only
on the chemical element from which the electrons originate but also upon the
chemical
l0 environments of that element. The results are expressed in atom percent.
For
example, if the analysis results read "1.5 percent F (NaF)", then that is
interpreted as
1.5 percent of the atoms on the surface are fluorine ions that are attached to
a sodium
IS
atom.
Hefferren Method for Assessment of Dentifrice Abrasivity
The Hefferren method measures the Radioactive Dentin Abrasivity (RDA) number,
also
called the Abrasivity Index (AI). This method utilizes the roots (dentin) of
extracted
human teeth, which are irradiated by a neutron flux. The teeth are mounted and
brushed
2o with a slurry of the toothpaste in question at a certain pressure and
number of strokes.
After brushing an aliquot of the slurry is dried and beta radiation is
measured. The more
abrasive the toothpaste under test, the more radioactivity associated with the
slurry. The
results are compared to a reference abrasive provided by the American Dental
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Association (ADA). The results are expressed as Abrasivity Index (AI). The AI
values
are interpreted for toothpaste as follows:
Less than 99 low abrasion
100 - 199 medium abrasion
200 - 250 high abrasion
greater than 250 unacceptable
Example 1 - Uncoated Calcium Carbonate vs. Coated Calcium Carbonate
1o Samples of uncoated and treated ground calcium carbonate products having a
surface area of 1.1 meters square per gram and a median particle size of 9.1
microns were
mixed in a beaker at 18 percent solids while a sodium monofluorophosphate
(MFP)
fluoride solution was added to a level of 0.88 percent. The slurries were
allowed to mix
for ten (10) minutes before filtration. The filter cakes were dried in an oven
of 110
degrees Celsius overnight and surface analyzed by XPS (x-ray Photoelectron
Spectroscopy).
Surface fluoride analysis results are presented in Table 1. In Table l, F
(CaFJ
denotes fluoride that has reacted with CaC03 and is unstable. The F (MFP)
denotes
fluoride that has not reacted with calcium carbonate and is therefore stable.
This form of
fluoride would be available to react with and protect teeth.
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TABLE 1
Surface Fluorine Content of Dried Filter Cakes (atom percent)
untreated 0.1% Na St 0.5%Na St 0.1% Guar 0.5% Guar
F (CaF2) 1.5 0.4 ~ --- 1.1 0.8
F (MFP) --- --- --- 0.9 1.5
Note: ---indicates an undetectable amount. A typical detection limit for
fluoride is
approximately 0.05 atom present.
o XPS analyses demonstrate that coating GCC with sodium stearate (NaSt)
results
in a stable system.
Coating with guar gum creates a stable system. When the level of guar gum is
increased from 0.1 percent to 0.5 percent, based on the dry weight of the guar
and the
dry weight of the calcium carbonate, the stability of the system increases.
Example 2 - Comparative Stability of Calcium Carbonate Using Other Treatments
The same laboratory experiments were conducted with ground calcium
carbonate (GCC) as in Example 1. Each treatment was applied at a level of 0.1
percent
and 0.5 percent based on dry weight of the treatment and dry weight of calcium
2o carbonate. The results of the surface fluoride analysis of the dried filter
cakes are
presented in Table 2:
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TABLE 2
Surface Fluoride Content
F (CaFz) F (MFP)
Untreated GCC 1.5 ---
CMC 0.1 % 0.7 ---
CMC 0.5 % 0.9 ---
Carrageenan 0.1 % 1.0 ---
Carrageenan 0.5 % 1.2 ---
Sodium Alginate 0.1 % 1.6 ---
to Sodium Alginate 0.5% 0.3 ---
Xanthan 0.1 % 0.6 ---
Xanthan 0.5 % failed ---
Gellan 0.1 % 1.2 ---
Gellan 0.5 % 1.1 ---
t 5 Linoleic 0.1 % 0.4 ---
Linoleic 0.5 % 0.4 ---
Hydroxystearic 0.1 %o 0.5 ---
Hydroxystearic 0.5 % 0.3 ---
20 Table 2 demonstrates that the calcium carbonate treated with the fatty
acids,
linoleic and hydroxystearic, and sodium alginate, at the higher treatment
levels, increase
stability. The polysaccharides, xanthan, and carboxymethylcellulose also
increase
stability but not as well as the fatty acids and the sodium alginate.
25 Example 3 - Effects of Treatments on Abrasivity in a Toothpaste Formulation
Four experimental GCC products treated with sodium stearate and guar gum at
0.1 percent and 0.5 percent were incorporated into a toothpaste formulation
with the
following composition:
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% W/W
Calcium Carbonate 18.00
Sident 22S 11.20
Titanium Dioxide 0.50
Sodium Saccharin 0.20
Sodium Benzoate 2.20
Glycerin 12.00
Sorbitol 15.00
Methyl Paraben 0.03
1 o Xanthan Gum 0.40
Sodium Lauryl Sulfate 1.30
PEG-8 7.00
Oil of peppermint 0.80
Purified water 31.37
t 5 Five toothpaste formulationstreated GCC abrasives were
containing tested for
abrasivity.
Sample Description Abrasivity Index
~ uncoated GCC 136
20 ~ GCC+O.Spercent stearic acid 128
~ GCC+O.lpercent stearic acid 120
~ GCC+O.lpercent guar gum 163
~ GCC+O.Spercent guar gum 165
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An abrasion index for toothpaste of:
99 and less - low abrasion
100-199 medium
200-250 high
> 250 unacceptable high abrasion
Stearic acid and guar gum treated GCC are in the medium abrasive range. The
treatment level on the calcium carbonate does not adversely affect abrasion.
15
19
