 |
Description  |
|
|
This invention relates to a gel dentifrice of desirable consistency.
Gel dentifrices typically contain only small amounts of water, say about
1-10% by weight and siliceous polishing material. When prepared with
antinucleating agent, they tend to be thin and have runny consistencies
initially and only attain firm and desirable consistencies having 48 to 72
hours or more. This delays processing and packaging and particularly makes
manufacture of striped dentifrices having a visually clear or opacified
gel dentifrice portion difficult.
Siliceous polishing agent is often employed in low water dentifrice gel
compositions prepared for toothbrushing. Low water gel dentifrices
containing such siliceous polishing agents as silica xerogel having an
average particle size between about 2 and 20 microns and generally a
surface area of at least about 300 m.sup.2 /gm, typically about 300-370
m.sup.2 /gm, or about 600-800 m.sup.2 /gm, which are described in U.S.
Pat. No. 3,538,230 to Pader et al, initially tend to be thin and runny
when prepared in the presence of an antinucleating agent. Similar
characteristics also tend to occur when the siliceous polishing agent
contains interbonded alumina in amounts up to about 10% by weight of
alumina in the polishing agent.
In the present invention, use is made of a precipitated, amorphous silica
gel which has been described in British Published Patent Application No. 2
038 303 A to Feig et al and in co-pending commonly assigned U.S. patent
application Ser. No. 576,046, filed Feb. 1, 1984 and now U.S. Pat. No.
4,528,181 issued July 9, 1985. Such material is available from Grace
G.m.b.H. as product such as Syloblanc 81, Syloblanc 81C and Syloblanc 82.
It is distinct from the types of xerogel which have been sold by W. R.
Grace and Co. under the trademark Syloid and which are particularly
described in U.S. Pat. No. 3,538,230 to Pader et al. Indeed, although some
products sold by Grace G.m.b.H. under the trademark Syloblanc were
formerly or are still available under the trademark Syloid, none of
Syloblanc 81, Syloblanc 81C or Syloblanc 82 have ever been available under
the trademark Syloid.
It is particularly noteworthy that the grades of the silica gel employed in
the present invention are less abrasive as the surface area increases
whereas the grades of silica xerogel which are described in U.S. Pat. No.
3,538,230 are generally more abrasive as their surface area increases.
In the present invention the hydrous silica gel polishing agent in
combination with an antinucleating agent containing at least one
phosphonic group provides a low water dentifrice initially having
desirable consistency. Such desirable consistency is not provided when
other siliceous polishing material is employed. When the dentifrice has an
initially runny consistency, it is characterized as having a generally low
and poorly defined initial yield point.
It is an advantage of this invention that a low water gel dentifrice
containing a hydrous silica gel and an antinucleating agent containing at
least one phophonic group is provided.
It is a further advantage of this invention that a process for improving
consistency of low water gel dentifrice is described.
Further advantages of the invention will be apparent from consideration of
the following specification.
In accordance with certain of its aspects, this invention relates to a gel
dentifrice comprising about 20-90% by weight of liquid vehicle comprising
water in amount of about 1-10% by weight of said dentifrice, about 0.05-5%
by weight of a gelling agent, about 10-50% by weight of a polishing agent
comprising a synthetic precipitated, amorphous silica gel having an
average particle size of 1 to 30 microns and
(a) surface area of 1 to 600 m.sup.2 /g,
(b) a pore volume of 0.05 to 0.5 cm.sup.3 /g,
(c) a product of surface area (in m.sup.2 /g).times.pore volume (in
cm.sup.3 /g) less than or equal to 240,
(d) a calculated pore diameter of 1.5 to 2.5 nm and
(e) a water content of less than 25% by weight; and
about 1-15% by weight of an antinucleating agent containing at least one
phosphonic group.
As indicated above, the synthetic precipitated silica is of the type
described in British Published Patent Application No. 2 038 303 A and U.S.
patent application Ser. No. 576,046 now U.S. Pat. No. 4,528,181. Specific
grades of the silica material described therein are suitable for use in
the practice of the present invention. Further, specific grades which are
particularly preferred are described in an October, 1980, trade
publication of Grace G.m.b.H. of Norderstadt, Germany, as Syloblanc 81 and
Syloblanc 82 as having the following typical physical and chemical
characteristics:
______________________________________
SYLO-
SYLOBLANC 81
BLANC 82
______________________________________
Average particle size
4 7
(according to Coulter) .mu.m
Wet screen residue (42 .mu.m) %
0.02 0.02
pH (5% suspension in water)
3 6
Surface area (B.E.T.) m.sup.2 /g
400 480
Loss on drying % 7 4
SiO.sub.2 content (on ignited
96 99
substance) %
Refractive index 1.46 1.46
______________________________________
In a variation available as Syloblanc 81C, the pH (5% suspension in water
is about 6-8.
Syloblanc 81 and 81C, in particular are highly effective in polishing
dental surfaces. Syloblanc 82 is lower in polishing effect but can be used
by consumers desiring such reduced effect. Likewise, grades of the silica
material may be proportioned in mixtures to produce appropriate polishing
characteristics. It is noteworthy that the dentifrices are compatible in
unlined aluminium dentifrice tubes even in the absence of phytate salt,
which is necessary to stabilize dentifrice containing siliceous polishing
agents, dual fluoride sources, and low amount of calcium ion for fluorine
retention and unlined aluminum tube compatibility in the invention
described in U.S. Pat. No. 4,528,181. The precipitated amorphous silica
gel is employed in amount of about 10-50% by weight, typically about
10-40% in a gel dentifrice.
Aqueous slurries of the silica materials (e.g. about 5 to 20% slurries)
typically have a pH of about 2 to 9. Since the dentifrice composition of
the present invention preferably has a pH (measured in 20% aqueous slurry)
of at least about 5.5, e.g. about 5.5-7.5, the pH of the dentifrice may be
adjusted with an appropriate material such as sodium hydroxide, etc.
In the present invention, desirable consistency is provided with the
presence of the antinucleating agent in amount of about 1-15% by weight,
preferably about 1-5%, when the synthetic precipitated, amorphous silica
gel illustrated by Syloblanc 81, Syloblanc 81C and Syloblanc 82 is
present.
Antinucleating agents containing phosphonic groups have been described in
the art as dentifrice components. They may provide desirable anticalculus
or antiplaque effect. Typical disclosures are in U.S. Pat. Nos. 4,348,381,
4,224,309 and 4,224,308 each to Gaffar et al; U.S. Pat. No. 4,215,105 to
Gaffar et al; U.S. Pat. Nos. 4,183,915 and 4,177,258 to Gaffar et al; U.S.
Pat. No. 4,144,324 to Crutchfield et al; U.S. Pat. No. 4,143,128 to Kim et
al; U.S. Pat. No. 4,137,303 to Gaffar et al; U.S. Pat. Nos. 4,123,512,
4,100,270, 4,098,880 and 4,042,679 to Gaffar; U.S. Pat. No. 4,064,164 to
Blum et al; U.S. Pat. Nos. 4,108,962, 4,108,961, 4,034,086, 3,988,443,
3,960,888, 3,941,772 and 3,925,456 to Ploger et al; U.S. Pat. No.
3,959,458 to Agricola et al; and U.S. Pat. Nos. 4,025,616, 3,937,807 and
3,934,002 to Haefele. Amounts of about 0.01-10% by weight, preferably
about 0.1-5% and most preferably about 1-3% of such antinucleating agents
can be included in the dentifrice of the present invention. They include
acid and non-toxic pharmaceutically acceptable salts (e.g. ammonium and
alkali metal, particularly sodium of
2-phosphonobutane tricarboxylic acid-1,2,4;
phosphonoacetic acid;
alkylene diamine tetramethylene phophonic acids containing 1-10 alkylene
groups;
polyalkyl bis-(phosphonomethylene)amine acid;
1,3-di-amino-alkane-1,1-diphosphonic acid as set forth in U.S. Pat. No.
4,064,164;
3-amino-1-hydroxypropane-1,1-diphosphonic acid;
azacycloalkane-2,2-diphosphonic acid containing 4-6 carbon atoms in the
heterocyclic ring;
pyrrolidone-5,5-diphosphonic acid wherein the hetero-N atom is substituted
with hydrogen or an alkyl group containing 1-6 carbon atoms;
azacyloalkane-2,2-diphosphonic acid wherein the hetero-N atom is
substituted with hydrogen or an alkyl group containing 1-3 carbon atoms
and containing 4-6 carbon atoms in the heterocylcic ring;
2-hydroxy-2-oxo-3-amino-3-phosphonyl-5-oxo-1-aza-2-phospha-cycloalkanes as
set forth in U.S. Pat. No. 3,925,456;
anticalculus agents of U.S. Pat. No. 3,959,458 typified by
ethane-1-hydroxy-1,1-diphosphonic acid.
Alkylene diamine tetramethylene phophonic salts, particularly lauryl sodium
salts of ethylene diamine tetramethylene phosphonic acid are preferred.
The dentifrice comprises about 20-90% by weight of a liquid vehicle with a
water content in the dentifrice of about 1-10% by weight. In the context
of the present invention, the water content of about 1-10% is exclusive of
water associated with humectant, surface-active agent solution, dye
solution, water of hydration, etc. Most of the liquid phase is humectant.
The liquid phase is characterized as having a refractive index of about
1.45 to 1.47, close to that of the hydrous silica gel. The low water gel
dentifrice is visually substantially clear or would be substantially clear
except for the presence of an opacifying agent, such as titanium dioxide.
Typical humectants include glycerine, sorbitol (e.g. 70% solution),
maltitol (e.g. 70-75% solution), and mixtures thereof. Water associated
with the humectants may be present in addition to the separate water
content set forth above.
The dentifrice also contains a gelling or binding agent as a solid vehicle
agent, although this may be in small amount, since the synthetic,
precipitated silica can effect a thickening or gelling of the dentifrice
into a creamy or pasty consistency. Gelling or binding agents include
alkali metal carboxymethyl cellulose, xanthan, Irish moss,
iota-carrageenan, gum tragacanth, hydroxyethyl cellulose, hydroxypropyl
cellulose, polyvinyl pyrrolidone, starch and mixtures thereof. Alkali
metal carboxymethyl cellulose, such as sodium carboxymethyl cellulose, is
preferred. Gelling agents may be used in amount of about 0.05-5% by
weight, typically about 0.05-2% and preferably about 0.1-1.5%.
Any suitable surface active or detersive material may be included in the
dentifrice compositions. Such compatible materials are desirable to
provide additional detersive foaming and antibacterial properties
depending upon the specific type of surface active material and are
selected similarly. These detergents are water-soluble compound usually,
and may be anionic, nonionic, amphoteric or cationic in structure. It is
usually preferred to use the water-soluble non-soap or synthetic organic
detergents. Suitable detersive materials are known and include, for
example, the water-soluble salts of higher fatty acid monoglyceride
monosulphate detergent (e.g. sodium coconut fatty acid monoglyceride
monosulphate), higher alkyl sulphate (e.g. sodium lauryl sulphate), alkyl
aryl sulphonate (e.g. sodium dodecyl benzene sulphonate, higher fatty acid
esters of 1,2-dihydroxy propane sulphonate) and the like.
Further surface active agents include the substantially saturated higher
aliphatic acyl amides of lower aliphatic amoino carboxylic acid compounds,
such as those having 12 to 16 carbons in the acyl radical. The amino acid
portion is derived generally from the lower aliphatic saturated
monoaminocarboxylic acid compounds. Suitable compounds are the fatty acid
amides of glycine, sarcosine, alanine, 3-aminopropanoic acid and valine
having about 12 to 16 carbons in the acyl group. It is preferred to use
the N-lauroyl, myristoyl and palmitoyl sarcoside compounds, however, for
optimum effects.
The amide compounds may be employed in the form of the free acid or
preferably as the water-soluble salts thereof, such as the alkali metal,
ammonium, amine and alkylolamine salts. Specific examples thereof are the
sodium and potassium N-lauroyl, myristoyl and palmitoyl sarcosides,
ammonium and ethanolamine N-lauroyl glycide and alanine. For convenience
herein, reference to "amino carboxylic acid compound," "sarcoside," and
the like refers to such compounds having a free carboxylic group or the
water-soluble carboxylate salts.
Such materials are utilized in pure or substantially pure form. They should
be as free as practicable from soap or similar higher fatty acid material
which tends to reduce the activity of these compounds. In usual practice,
the amount of such higher fatty acid material is less than 15% by weight
of the amide and insufficient to substantially adversely affect it, and
preferably less than about 10% of said amide material.
Other particularly suitable surface-active materials include nonionic
agents such as condensates of sorbitan monostearate with approximately 20
moles of ethylene oxide, condensates of ethylene oxide with propylene
oxide, condensates of propylene glycol ("Pluronic" materials) and
amphorteic agents such as long chain (alkyl)amide-alkylenealkalated amine
derivatives, which are available under the trademark "Miranol" C.sub.2 M.
Cationic surface active germicides and antibacterial compounds such as
diisobutylphenoxyethyoxyethyl dimethyl benzyl ammonium chloride, benzyl
dimethyl stearyl ammonium chloride, tertiary amines having one fatty alkyl
group (of from 12-18 carbon atoms) and two (poly)oxyethylene groups
attached to the nitrogen (typically containing a total of from about 2 to
50 ethanoxy groups per molecule) and salts thereof with acids, and
compounds of the structure
##STR1##
wherein R represents a fatty alkyl group containing from about 12 to 18
carbon atoms, and x, y and z total 3 or higher, as well as salts thereof
with mineral or organic acids, may also be used. It is preferred to use
from about 0.05 to 5% by weight of the foregoing surface-active materials
in the oral preparation of the present invention.
The compositions of the present invention may also contain a
fluorine-containing compound having a beneficial effect on the care and
hygiene of the oral cavity, e.g., diminution of enamel solubility in acid
and protection of the teeth against decay which do not substantially
detract from the clarity of the dentifrice. Examples of known fluorine
materials include sodium fluoride, potassium fluoride, stannous fluoride,
stannous chlorofluoride, potassium stannous fluoride (SnF.sub.2 KF), and
complex fluorides such as sodium fluorozirconate and particularly sodium
monofluorophosphate. These materials, which dissociate or release
fluorine-containing ions, suitably may be present in an effective but
non-toxic amount, usually within the range of about 0.01 to 1% by weight
of the water-soluble fluorine content thereof. Sodium fluoride and sodium
monofluorophosphate are particularly preferred, as well as mixtures
thereof.
Various other materials may be incorporated in the dental creams of this
invention. Examples thereof are opacifiers, preservatives, stabilizers,
silicones, chlorophyll compounds and ammoniated materials such as urea,
diammonium phosphate and mixtures thereof. These adjuvants are
incorporated in the instant compositions in amounts which do not
substantially adversely affect the desired properties and characteristics
and are suitably selected and used in conventional amounts.
For some purposes it may be desirable to include antibacterial agents in
the compositions of the present invention. Typical antibacterial agents
which may be used in amount of about 0.01% to about 5%, preferably about
0.05 to about 1.0%, by weight of the dentifrice composition include cetyl
pyridinium chloride, benzethonium chloride as well as:
N.sup.1 -4 (chlorobenzyl)-N.sup.5 -(2,4-dichlorobenzyl)biguanide;
p-chlorophenyl biguanide;
4-chlorobenzhydryl biguanide;
4-chlorobenzhydrylguanylurea;
N-3-lauroxypropyl-N.sup.5 -p-chlorobenzylbiguanide;
1,6-di-p-chlorophenylbiguanidohexane;
1-(lauryldimethylammonium)-8-(p-chlorobenzyldimethylammonium)
5,6-dichloro-2-guanidinobenzimidazole;
N.sup.1 -p-chlorophenyl-N.sup.5 -laurylbiguanide;
5-amino-1,3-bis(2-ethylhexyl)-5-methylhexahydropyrimidine; and their
non-toxic addition salts.
Any suitable flavouring or sweetening materials may be employed in
formulating a flavour for the compositions of the present invention.
Examples of suitable flavouring constituents include the flavouring oils,
e.g. oils of spearmint, peppermint, wintergreen, sassafras, clove, sage,
eucalyptus, marjoram, cinnamon, lemon and orange, as well as methyl
salicylate. Suitable sweetening agents include sucrose, lactose, maltose,
sorbitol, sodium cyclamate, sodium saccharine, dipeptides of U.S. Pat. No.
3,939,261 and oxathiazin salts of U.S. Pat. No. 3,932,606. Suitable flavor
and sweetening agents may together comprise from about 0.01 to 5% or more
of the composition.
The dentifrice is packaged in a container from which it can be readily
extruded such as a pressure differential or mechanically operated dental
cream dispenser or a lined or unlined aluminium tube or wax lined lead
tube or plastic tube, which may be laminated with aluminium. It may be
employed as a complete dentifrice or as a stripe within or on the surface
of a similarly formulated but contrasting dentifrice or a stripe in
conjunction with a substantially different dentifrice formulation.
The dentifrice is most desirably prepared in order to attain optimum,
desirable consistency by forming a premix of the gelling agent with the
liquid vehicle components, e.g. water and humectant adding thereto the
antinucleating agent containing at least one phosphonate group and then
blending therewith the hydrous silica gel. If employed, additional
ingredients such as surface active agents may then be added. In
processing, the hydrous silica gel is not added before the antinucleating
agent.
Although the invention is described with regard to the illustrative
example, it will be apparent to one skilled in the art that various
modifications may be made thereto which fall within its scope. All amounts
are by weight unless otherwise indicated.
EXAMPLE 1
The following opacified gel dentifrice is prepared and placed in an unlined
aluminium tube:
______________________________________
PART Ia
Glycerine 17.000
Sorbitol (70%) 42.900
Sodium carboxymethyl cellulose
0.300
Sodium saccharin 0.200
Sodium fluoride 0.220
Titanium dioxide 1.000
PART Ib
Water 5.000
Ethylene diamine tetra-
1.870
methylene phosphonic acid
Sodium hydroxide 0.750
PART II
Precipitated amorphous
20.000
hydrous silica gel*
PART III
Sodium lauryl sulphate
1.760
Glycerine (supplemental
8.000
addition)
PART IV
Flavour 1.000
pH (20% slurry) 7.0
______________________________________
*Syloblanc 81 available from Grace G.m.b.H.;
The dentifrice is prepared as an opacified gel by forming a preblend of the
humectants, gelling agent, sweetener, fluoride, and opacifier
corresponding to Part Ia, mixing Part Ib containing low water content for
the dentifrice and partially neutralized antinucleating agent. The heat of
neutralisation produced in this mixing step alleviates the need to apply
an external heat source, thereby providing an efficient low-cost method of
dentifrice formation. The hydrous silica gel polishing agent (Part II) is
then added followed by mixing therewith additional minor amount of a
humectant and the surface active agent (Part III) and then the flavor
(Part IV).
The low water opacified gel dentifrice has desirable consistency upon
formulation. When the preparation procedure is modified, the rheology is
less than optimum but still quite desirable, particularly compared to
corresponding dentifrice formulations prepared with other siliceous
polishing agents, even when supplemented with an additional thickening
ingredient.
The illustrated dentifrice can be modified with similar rheological results
by replacing the partially neutralized ethylene diamine tetramethylene
phosphonic acid with other antinucleating agents including sodium salts of
2-phosphonobutane tricarboxylic acid-1,2,4 and
ethane-1-hydroxy-1,1-diphosphonic acid.
In accordance with further modifications, Syloblanc 81 can be replaced by
Syloblanc 81C, Syloblanc 82 and a 1: mixture of Syloblanc 81 and 82.
In the example sodium cyclamate may replace sodium saccharin.
It will be apparent to those skilled in the art that further modifications
of the examples illustrative of the invention may be made thereto.
* * * * *
|
|
 |
|
 |
Description |
|
