Note: Descriptions are shown in the official language in which they were submitted.
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~ his invention relates to a dental cream composition
having a desirable rheological character. In particular
it relates to a dental cream composition of smooth
texture with little tendency to form grain, particularly
upon aging at low temperatures.
Calcium carbonate or chalk has long been used as a
dental polishing agent. In earlier times, in spite of
its effectiveness in polishing teeth, it had disadvantages
in that it tended to make dental cream somewhat slimy
in feel. More recently, however, grades of calcium
carbonate have come into use which substantially avoid
this problem.
NeverthelessJ it has been observed thst in dental
creams containing calcium carbonate, including modern
grades of the material, when the cream further contains
sodium lauryl sulphate as a surface active agent, and
particularly sodium lauryl sulphate having a broad
distribution of alkyl chain lengths, such as about 1-8%
C10; 40-70% C12; 13-30% C14; 5-16% C16; and 0-23% C18;
grain formation does occur after storage at low temeratures
e.g. between about -7 to 7C.
It is an object of this invention to provide a dental
cream composition comprising calcium carbonate and sodium
lauryl sulphate having a broad distribution of alkyl
chain lengths which composition has desirable rheological
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characteristics and is substantially grain free.
According to the present invention a dental cream
composition comprises from 20 to 75% by weight of a
calcium carbonate polishing material, from 0.1 to 5%
by weight of a surface active material including sodium
lauryl sulphate having a broad distribution of alkyl
groups containing 10 - 18 carbon atoms, the C12 content
being about 40 to 70% by weight, and from 0.2 to 1% by
weight of an additive which is an M4 pyrophosphate or an
anionic phosphate ester comprising a mixture of monoester
of the formula
R~OC2H4)n ~-OM and
OM
diester of the formula
R~oc2H4)n~Y-o~c2H4o)nR
IM
wherein M is hydrogen, alkali metal or ammonium, R is
an alkyl group of 10 - 20 carbon atoms and n is an integer
from 1 to 6.
Calcium carbonate is available in various grades,
particularly as precipitated chalk. For example, grades
may have an apparent density of about 0.47 - 0.61 gms/cc;
a flow point of about 19 to 25; a moisture loss at 105C
of about 1 to 2%; a particle size such that at least 99.7%
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of the particles are finer than 74 microns (pass through
United States 200 sieve), the median size is about 4 to 9
microns and not more than 90% are less than 18 microns; and
the material is composed of calcite and aragonite in a
ratio of from about 1:9 to 3:1, typically about 1:10,
1:1 or 3:1. Suitable grades are available from John
and E. Sturge Ltd., Birmingham, England for instance
as Sturcal H* and from Johann Schaefer Kalkwerke, Diez,
West Germany as Schaefer AC*.
The polishing material preferably comprises from
40-to 55%, of the dental cream and preferably at least
about 95% of the polishing material is calcium carbonate.
In addition to calcium carbonate the polishing material
may optionally contain as up to about 5% of its content
an additional polishing agent such as dicalcium phosphate
(anhydrous or dihydrate), tricalcium phosphate, dimagnesium
phosphate, trimagnesium phosphate, insoluble sodium
metaphosphate, hydrated alumina or silica.
Sodium lauryl sulphate has long been used in dental
cream compositions but it has generally been used as a
"narrow cut" material iTI which at least 90%, even 99%,
of the alkyl groups are C12. Dental creams containing
calcium carbonate and "narrow cut" sodium lauryl sulphate
often do not become grainy, even upon aging at low
temperatures. It is when the sodium lauryl sulphate of
*Trademark _ 3 _
f..,
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broad alkyl distribution is employedJ that the problem
of grain upon aging at low temperatures can be
recognized. A particular sodium lauryl sulphate employed
for the present invention contains about 3% C10; 56% C12;
21% C14; 9% C16 and 11% C18 alkyl groups and is
commercially available in the form of needles as "LZV"*
from Marchon Division of Albright and Wilson, Whitehaven,
England. Further broad cut grades of sodium lauryl
sulphate which may be employed are Tensopol* ACL 17 from
Tensia S.A., Liege, Belgium and Texapon* ZHC from Henkel
and Cie., Dusseldorf, West Germany. Such grades of sodium
lauryl sulphate include about 40 to 70% C12 of their
alkyl distribution. More particularly, they typically
have an alkyl distribution of about 1 to 8% C10; 4 to 70%
C12; 13 to 30% C14; 5 to 16% C16; and 0 to 23% C18. The
alkyl groups are substantially straight chain ~normal).
In addition to sodium lauryl sulphate of broad alkyl
distribution, the dental cream optionally may include an
additional surface active agent. Such agents may include
anionic materials, for instance, water-soluble salts of
higher fatty acid monoglyceride monosulphate (e.g., sodium
coconut fatty acid monoglyceride monosulphate), alkyl
aryl sulphonate (e.g., sodium dodecyl benzene sulphonate),
higher fatty acid esters of l,2-dihydroxy propane sulphonate
(e.g., sodium coconut fatty acid ester of 1,2-dihydroxy
*Trademark - 4 -
~,:
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propane sulphonate) or anionic phosphate ester of the
type indicated above which is also effective as an
additive to reduce grain formation.
A nonionic or ampholytic surface active agent may
also be present, such agents including nonionic agents such
as sorbitan monostearate with approximately 60 moles of
ethylene oxide, condensates of ethylene oxide with
propylene glycol (available under the trademark "Pluronics")
and amphoteric agents such as quaternized imidazole
derivatives which are available under the trademark
"Miranol" such as Miranol C2M. It is preferred that the
total amount of surface active agent does not exceed about 5%
by weight of the oral composition. The total surface active
material content of the dental cream is about 0.1 to 5%
by weight. Preferably about 1 to 2% by weight of sodium
lauryl sulphate of broad alkyl distribution is present.
The additive which reduces the grain formation
upon aging at low temperature, such as about -7 to 7C,
is a phosphate material, particularly a pyrophosphate or
the anionic phosphate ester mixture of monoester and
diester as defined above. When the anionic phosphate
ester is employed, it may also serve as part of the surface
active material.
The M4 Pyrophosphate may be tetrasodium pyr~phosphate
in its anhydrous or hydrated forms. (Na4P207 1oH20~ is a
.X!
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preferred material. The corresponding tripolyphosphate
is not believed to be effective in grain reduction.
The anionic phosphate esters are mixtures of mono
and di-esters of the formulas hereinabove set forth.
They are available from MoDo Kemi Aktiebolaget, formerly
Berol Al<tiebolaget, of Sweden under the name Berol* and
may include an anionic triester moiety to, as well as
some non-ionic portion. Berol 729 has alkyl chain
lengths of 16 to 18 carbon atoms and contains series of
4 ethylene oxide units. Since the acid form of Berol
729 typically provides a completed oral preparation
with a pH below 6, this material is generally used in
neutralized or partially neutralized form in order to
assure a pH above about 6 to the completed oral preparation.
Further anionic phosphate esters which may be used
in acid or neutralized forms are Berol 525 which contains
alkyl groups of 10 to 18 carbon atoms and series of
5 ethylene oxide units and Berol 513 which contains
alkyl groups of 16 to 18 carbon atoms. However, use
of Berol 525 may also provide a completed oral preparation
with a pH below 6 and it is preferred to use it in
neutralized or partially neutralized form. Further
Berol anionic phosphate esters are available as Berol
521, Berol 724 and Berol 733. The weight ratio of mono-
ester to diester may vary, typically from about 1:10
*Trademark - 6 -
~, .
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to 10:1.
The grain reduction additive is employed in amount
of from 0.2 to 1% by weight, preferably about 0.2 to 0.5%.
When a dentifrice containing calcium carbonate and sodium
lauryl sulphate having a broad alkyl group distribution,
but not including the anti-grain additive is prepared,
grain formation can be observed after aging for one month
at a low temperature, such as about -7 to 7C, typically
4C.
The dental cream includes as a vehicle for the polish-
ing material, grain reduction additive and other ingredients,
liquids and solids proportioned to form an extrudable
creamy mass of desirable consistency. In general, liquids
in the dental cream will comprise chiefly water, glycerine,
sorbitol, propylene glycol, or the like, including suitable
mixtures thereof. It is advantageous usually to use a
mixture of both water and a binder or humectant such as
glycerine and/or sorbitol. It is preferred to use glycerine
or mixtures of glycerine with sorbitol. The humectant
is generally used in an amount between about 20 and 25%,
and preferably about 22%. The total liquid content will
generally be about 20 to 65% by weight of the formation,
with water being in an amount to bring the total of com-
ponents to 100%.
It is preferred to use also a gelling agent in dental
.~,,;1
33SO
creams such as the natural and synthetic gum and gum-like materials, e.g.,
Irish moss, gum tragacanth, sodium carboxymethylcellulose, polyvinyl
pyrrolidone, starch and the like; all being referred to as "gum". The Irish
moss and sodium carboxymethylcellulose are compatible particularly and are
preferred gelling agents. The gum content is usually in an amount up to
about 10% and preferably about 0.5 to 5% by weight of the formulation, with
gum in an amount of about 0.9 to 1.3% especially preferred.
The total of liquid and gelling agent (gum) form the dental cream
vehicle in which the other components are dispersed or dissolved.
Minor amounts of ingredients such as sweetener, flavour and,
should an unlined aluminum tube be used, sodium silicate, may be employed.
The following specific examples are further illustrative of the
nature of the present invention but it is understood that the invention is
not limited thereto. Oral compositions are prepared in the usual manner,
except as indicated, and all amounts and proportions are by weight except
as otherwise indicated.
LXAMPLE
The following dentifrices were prepared and placed in unlined
aluminum tubes:
.. .
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Components Parts
A B C
Glycerine 6.060 6.060 6.060
Sodium carboxymethyl cellulose 1.200 1.200 1.200
Sodium saccharin 0.200 0.200 0.200
Sodium silicate 0.200 0.200 0.200
Sorbitol (70%) ` 16.000 16.000 16.000
Tetrasodium pyrophosphate --- 0.500 ---
Berol 513* --- --- 0.500
Deionized water 23.433 22.933 22.933
Calcium carbonate** 42.000 42.000 42.000
Sodium lauryl sulphate LZV***1.807 1.807 1.807
Flavour 1.100 _1.100 1.100
pH 8.65 9.44 8.20
*Berol 513, employed in dentifrice C is a mixture of anionic
phosphate monoesters and diesters of the earlisr indicated formulas in
which the alkyl group contains 16 to 18 carbon atoms. It is a pasty mate-
rial with a density of about 1.050/cm3 at 30C. It is available from MoDo
Kemi Aktiebolaget, of Sweden.
**The calcium carbonate employed in dentifrices A, B, and C is
Sturcal H chalk, available from John ~ E. Sturge Ltd., Birmingham, England.
***The sodium lauryl sulphate employed in dentifrices A, B ~ C is
LZV, a broad-cut needle material available from Marchon Division of
Albright and Wilson.
After aging for three months at 4 C, dentifrice A has an appear-
ance which can be noticed as somewhat rough and grainy. On the other hand,
the presence of tetrasodium pyrophosphate in dentifrice B and of Berol 513
- in dentifrice C, reduces grain, such that after storage for three months at
4C, dentifrice B is slightly rough only at the tube nozzle, but is other-
wise satisfactory and indeed shiny; dentifrice C is satisfactory and shiny
after storage for three months at 4C.
Likewise, improvements are observed when tetrasodium pyrophosphate
or the organic phosphate ester is present in dentifrices containing calcium
carbonate available as Schaefer AC from and broad-cut sodium lauryl sul-
phate, including LZV as well as needles of Tensapol ACL7 available from
Tensia, S.A., Liege, Belgium and needles of Texapon ZHC, available from
Henkel and Cie. Dusseldorf, West Germany.
A grain problem also exists when the formula contains 40% calcium
carbonate, such as Sturcal H and 2% dicalcium phosphate as polishing mate-
rials and broad-cut sodium lauryl sulphate, such as LZV, which problem is
reduced by the presence of tetrasodium pyrophosphate or the organic phos-
phate ester.
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