Note: Descriptions are shown in the official language in which they were submitted.
,WO 95/13412 PCT/US94/13208
-1-
DISPOSABLE TOOTHBRUSH HAVING MINT FLAVORED
TOOTHPASTE COMPOSITION BONDED TO
BRISTLES THEREOF
BACKGROUND OF THE INVENTION
To accommodate the busy and often harried
traveler, disposable toothbrushes have been designed
that can be used away from home, for example on a
trip, or that can be offered for single use in
establishments receiving the public, such as hotels
and restaurants. These disposable toothbrushes have
eliminated the need for a separate tube of
toothpaste by incorporating in or on the brush a
sufficient dose of a flavored toothpaste for
brushing the teeth, the flavor being added to
encourage oral hygiene practices. Many such prior
art disposable toothbrushes are complex and/or
expensive, as where a mechanism is included for
distributing the toothpaste onto the bristles just
prior to use. In other prior art disposable
toothbrushes, the toothpaste is preapplied to the
bristles, but such toothbrushes have proved
unstable, in that the flavoring dissipates after a
relatively short period of time, which is
impractical as commercial considerations require a
reasonable shelf life. As a result, prior art
disposable toothbrushes have, for the most part, not
proved commercially successful, primarily because no
known prior art disposable toothbrush has satisfied
the multiple criteria of a preapplied toothpaste
WO 95/13412 PCT/US94/13208
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thereby eliminating the need for a distribution
mechanism, a reasonable shelf life, and a low
manufacturing cost. Regarding manufacturing costs,
it is well known that service establishments, such
as hotels, will not provide to their patrons
disposable items which exceed a preestablished cost.
Hospitals, of course, also provide toothbrushes
to their patients. Typically, hospitals provide a
toothbrush and a separate tube of toothpaste, the
tube typically including sufficient toothpaste for
a limited number of uses. This, however, poses two
problems. First, there is a risk of transmission of
infectious disease, as when a patient places his/her
toothbrush on a sink, etc. Secondly, in the case of
a patient having use of only one arm, as is
sometimes the case when patients are treated
intravenously, it is difficult for the patient to
manipulate the toothpaste onto the bristles of the
toothbrush.
For the foregoing reasons, there is a need
for an individually wrapped, inexpensive disposable
toothbrush having a toothpaste composition
distributed over the bristles of the toothbrush and
in which the flavoring does not dissipate over a
reasonable shelf life.
216003
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OBJECTS AND SUMMARY OF THE INVENTION
It is therefore an object of the present
invention to provide a flavored toothpaste
composition bonded to a toothbrush, wherein the
flavor is stabilized and long-lasting.
It is a further object of the invention to
provide a disposable toothbrush which is coated with
an amount of toothpaste sufficient for a single
tooth brushing operation such that the toothbrush
may be disposed of after initial use.
It is another object of the invention to
provide a method of manufacture of a disposable
toothbrush and toothpaste product with a long-
lasting, stabilized flavor.
It is still another object of the
invention to provide a disposable toothbrush and
toothpaste product that can be produced at low cost .
It is yet another object of the invention
to provide a disposable toothbrush that is both safe
and convenient to use, e.g., in a hospital setting.
The present invention is thus directed to
a disposable toothbrush and toothpaste product
obtained by a process which involves the
polymerization of selected monomers and prepolymers
and the chemical grafting of the resulting polymer
to the bristles of the toothbrush. More
particularly, the process of the present invention
comprises the steps of contacting the bristles of
the toothbrush (in general hereinafter being
referred to as "the substrate") with a composition
containing a ferrous salt as the graft initiator, a
monomer/prepolymer, and a catalyst which activates
polymerization by the ferrous ion, whereby the
ferrous ions are reduced by the substrate with free
radicals being formed as a result on the substrate.
The monomer/prepolymer attaches itself to these free
radical sites, and the resulting polymer forms an
intimate covalent bond with the substrate. The
S a
216003
- 4 -
toothbrush containing the toothpaste composition is
then dried to complete the graft bonding of the
toothpaste to the substrate.
The strength of the resulting bond can be
adjusted so that the flavored toothpaste is
immediately activated when brought into contact with
normal mouth fluids, i.e., water and saliva, and is
released by the scrubbing action of the bristles
against the teeth, imparting a desirable flavor to
the teeth and mouth of the user thereof.
In one aspect, the present invention
provides a toothbrush and toothpaste combination
comprising: (a) a plurality of polymeric bristles;
and (b) a toothpaste composition comprising a
polymer covalently bonded to the surface of the
bristles.
In another aspect, the present invention
provides a toothbrush and toothpaste combination
comprising: (a) a plurality of polymeric bristles;
and (b) a toothpaste composition comprising a
polymer graft polymerized to the surface of the
bristles.
In yet another aspect, the present
invention provides a toothbrush comprising a
plurality of bristles having a toothpaste
composition graft polymerized to the bristle
surfaces forming a coating thereon.
In yet another aspect, the present
invention provides a toothbrush and toothpaste
combination comprising: (a) a plurality of polymeric
bristles; and (b) a toothpaste composition
comprising a polymer covalently bonded to the
surface of the bristles, the covalent bond being the
result of graft polymerization involving a grafting
solution comprising: (i) at least one acrylic or
vinyl monomer or prepolymer selected from the group
consisting of acrylic acid, polyacrylic acid and
polyvinyl alcohol, methacrylic acid, ethyl acrylate,
21~~0~~
- 4a -
ethyl methacrylate, isobutylmethacrylate and methyl
acrylate, and ranging from about 0 . 0001 o to about 2
by weight of the composition, (ii) a graft initiator
ranging from about O.OOOOlo to about O.Olo by weight
of the composition, and (iii) a peroxide catalyst
ranging from about O.OOlo to about to of weight of
the composition.
In yet another aspect, the present
invention provides a toothbrush and toothpaste
combination comprising: (a) a plurality of polymeric
bristles; and (b) a toothpaste composition
comprising a polymer graft polymerized to the
surface of the bristles, the graft polymerization
involving the use of a grafting solution comprising:
(i) at least one acrylic or vinyl monomer or
prepolymer selected from the group consisting of
acrylic acid, polyacrylic acid and polyvinyl
alcohol, methacrylic acid, ethyl acrylate, ethyl
methacrylate, isobutylmethacrylate and methyl
acrylate, and ranging from about 0 . 0001 o to about 2 0
by weight of the composition, (ii) a graft initiator
ranging from about 0 . 00001 % to about 0 . O1 % by weight
of the composition, and (iii) a peroxide catalyst
ranging from about 0.0010 to about to of weight of
the composition.
a
1
WO 95/13412 PCT/US94/13208
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Mechanism of Chemical Grafting
A. As Applied to Natural and Polymeric Substrates
Chemical grafting involves activation of
a substrate. Once the substrate has been activated,
chains of monomers linked by carbon-carbon bonds
grow on the substrate, bonding to the substrate
without damaging any of the existing positive
characteristics of the materials involved. Many
materials, both naturally occurring and synthetic,
possess active hydrogens which are more reactive
than the "bulk hydrogens," the tertiary hydrogen in
polypropylene for example.
Thus, graft initiators (G.I.) have the
capacity of removing these active hydrogens and
concomitantly initiating the growth of polymer
chains at the site from where the active hydrogen
was removed. In the case of polypropylene, this can
be represented as follows:
CH3 CH3 CH3
I I G.I. (1)
CHz- C CHZ C CHZ C ---------
i
H H H
CH3 CH3 CH3
( 2 ) I CHZ=CH
CHZ - C ° - CH2 - C ° - CH2 C ° X
WO 95/13412 PCT/US94/13208
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CH3 CH3 CH3
t i i
( 3 ) CHZ - C CHZ C CHz C
(CH2__CH)n____H(CHz__CH)n____H(CHz__CH)n__H
f t 1
X X X
In this illustration, (°) can represent
either a free radical, anion or cation, depending on
whether the G.I. removes a hydrogen and one
electron, no electrons or twc electrons,
respectively. CH2=CHx represents a unit of vinyl
monomer where "x" governs the property or properties
obtained. In many instances a mixture of monomers
is employed and often more than one property can be
altered in one processing step. These polymer
chains, whose length can be controlled, are strongly
attached to the substrate. The linkage between the
graft polymer and the substrate is covalent in
nature, and therefore, the graft polymer cannot be
leached from the substrate. In essence, chemical
grafting is a matter of growing polymer chains on
the backbone chain of a substrate. The graft
polymer chains are formed from vinyl monomers or
monomers containing appropriate functionality, e.g.,
groups such as hydroxyl, carboxyl, epoxy, amide,
amine, anhydride.
B. Chemical Grafting as Apt~lied to a Nvlon
Polvnropvlene or Polvester Substrate of a Toothbrush
In the case of a nylon, polypropylene or
polyester substrate, such as a toothbrush bristle,
the chemical grafting is carried out via the
abstraction of the hydrogen atom from the
-CONH- group (nylon),
~~~~~~3
CH3 O
n
H2C----C----CH2 PE---C---OH
I
H
(polypropylene) (PP] or (polyester) [PE]
with the graft initiator to form a free radical
which then reacts with a graft polymer
solution, by which graft polymerization commences.
The sequence of reaction steps involved in the
chemical attachment of the monomer/prepolymer onto
the toothbrush substrate is believed to take place
as follows:
S-H + GI' -------j S° + H' + GI (1)
nylon, PP graft free radical formation
or PE initiator
substrate
S ° + CHZ = CH - - - - -j S - CHZ - CH ° ( 2 )
x x
monomer initiation
S-CH2-CH° + (CH2-CH)n _____j S_([~2-CH)n-CHZ-CH° (3)
l ~ I \
X X X X
propagation
R10H + GI' -----j R10° + H' + GI (4)
Menthol
The graft polymerization shown in steps (1) - (4)
may be terminated by radical combination which may
occur as:
A
_g_
S - ( CHz - CH ) n - CHz - CH ° + R10 °
I I
x x
---------j~ S - (CH2-CH) n -CH2-CHORl (5)
X X
The foregoing reactions take place in the presence
of a peroxide catalyst which concurrently
regenerates the graft initiator forming a free
radical as shown in reaction step (6).
RZOOH + GI -----~ R20° + OH' + GI' (6)
peroxide
Reaction (1) provides a radical site on an exemplary
substrate (S-H) by the reduction of the graft
initiator and oxidation of the substrate to
transform the substrate into a free radical.
Reaction (2) illustrates the grafting of an
exemplary monomer to the activated substrate (S°) at
the free radical site to form a graft polymer
radical on the substrate. This is followed by
propagation in reaction (3). Reaction (4)
illustrates the formation of a menthol radical,
e.g., from a peppermint compound. Reaction (5)
illustrates chain termination via combination of the
menthol radical with the activated substrate graft
polymer formed in step ( 3 ) , the end result being the
chemical attachment of the mint flavor to
the surface of the toothbrush bristles. Reaction
(6) illustrates the regeneration of the graft
initiator ion by the presence of peroxide in the
monomer solution.
A
-9-
Method of Preparation of the Mint-Flavored
Toothpaste Formulation
The present invention is directed to a
polymeric toothpaste composition that is chemically
grafted to the bristles of a toothbrush to form a
strong adhesion to the bristles over an extended
period of time. As previously stated, chemical
grafting involves the use of monomers/prepolymers,
a catalyst, and a graft initiator along with other
excipients in the composition. Thus, the polymeric
toothpaste composition of the present invention
requires the use of monomers/prepolymers, a graft
initiator and catalyst, and may also include other
excipients such as fillers, surfactants, buffers,
pigments and flavoring.
The monomers and prepolymers are vinyl
monomers and acrylic and vinyl prepolymers which
chemically bond to the bristles via a free radical
system. The monomers and prepolymers are preferably
acrylic monomers having one or more hydroxyl and
carboxyl groups. Some of the monomers and
prepolymers of this type are the following:
polyvinyl alcohol, acrylic acid, polyacrylic acid,
methacrylic acid, ethyl acrylate, ethyl
methacrylate, isobutylmethacrylate, and methyl
acrylate. Also, mixtures of two or more monomers
can be used. Polyvinyl alcohol, acrylic acid and
polyacrylic acid are preferred.
The formulation is prepared by taking the
ingredients in the order as indicated in the
examples or any other convenient order.
Ferrous ions are preferred as graft
initiators for the , grafting of desired
monomers/prepolymers onto the bristles, but other
metal ions such as Ag' ions could also be used or any
other metal ion which is safe for mouth application.
The presence of a small amount of a
peroxide catalyst, preferably hydrogen peroxide,
helps to regenerate the gra't initiator system in
A
WO 95113412 PCT/IJS94/13208
,
~~~6
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the process which in turn provides free radicals for
further chain graft polymerization. Other
representative peroxides include peracetic acid and
urea peroxide.
The amounts of the reactants employed is
not a critical feature of the invention. For
obvious economical reasons, the amounts of
monomer/prepolymer, graft initiator and catalyst
employed in the system will be the minimum amounts
necessary to .complete the reaction as previously
described herein. The amounts of monomer and
prepolymer employed will normally range from about
0.0001% to about 2% by weight of the composition,
though the preferred concentration ranges from about
0.0001% to about 0.2o by weight. The amount of
graft initiator ranges from about O.OOOOlo to about
0.01% by weight, preferably from about 0.00001% to
about 0.001%. The amount of peroxide catalyst
employed will normally range from about 0.001% to
about 1% by weight, preferably from about 0.001% to
about 0.5%.
Suitable materials for use as flavors~are
those which allow the user to detect a strong,
noticeable flavor while permitting maintenance of an
acceptable product appearance. The flavors may be
of natural or synthetic origin. Such flavors
include peppermint, spearmint, wintergreen,
cinnamon, and the like; fruit flavors such as
cherry, strawberry, lime, and the like. Preferred
flavors for use in toothpaste include peppermint and
spearmint.
Examples of auxiliary excipients utilized
in the present invention include fillers,
surfactants, buffers and. pigments.
WO 95/13412 PCT/US94/13208
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The formulation described herein has
several advantages. First, it eliminates the need
for a complex and expensive article that is intended
to be used only once. Second, it eliminates, when
traveling, the need for packing both a toothbrush
and a tube of toothpaste. And finally, the intimate
bond that is formed when the toothpaste is applied
to the bristles locks in the freshness and flavor
for a long period of time.
In the preferred embodiment of the
invention, the bristles of the toothbrush are dipped
into a toothpaste that contains monomers,
prepolymers, graft initiator ions, peroxide ions and
other excipients of the composition. The coated
samples are then air dried at room temperature for
approximately 30 to 40 minutes, whereby the hydroxyl
and carboxyl groups from the monomers/prepolymers in
the toothpaste polymerize to form a strong adhesion
to the bristles of the toothbrush.
Where the toothpaste is applied to the
bristles as a single coat, the formulation consists
basically of the monomer/prepolymer, catalyst, graft
initiator, pigment, flavoring and other auxiliary
excipients. The desired amounts of each filler,
namely calcium carbonate, sodium hydrogen carbonate,
sodium lauryl sulfate, potassium tripolyphosphate
and sodium fluoride are combined in a container and
mixed until a homogeneous mixture is obtained.
Likewise the desired amounts of the
monomer/prepolymer, graft initiator and pigment are
combined in a container and stirred until the
solution is uniform. The mixture of fillers is then
added in small increments with continuous stirring
to the uniform solution. The polyacrylic acid is
X176~~~
-12-
then added, followed by the mint flavored compound,
and the contents are blended to a smooth paste . The
hydrogen peroxide is finally added and the paste is
mixed again until uniform. The prepared reactive
formulation may then be applied to the toothbrush by
dipping the toothbrush into the toothpaste and then,
if necessary, the product may be exposed to air
drying for 30 to 40 minutes to complete the graft
bonding. If desired, the drying process may be
accelerated by subjecting the product to heat, e.g.,
at a temperature of about 212°F to 300°F for 1 to 2
minutes.
The following examples illustrate
formulations which may be used in the invention.
EXAMPLE 1
Composition ~ WeiQht '
Parts
1. Calcium carbonate 500.00
2. Sodium hydrogen carbonate 20.00
3. Sodium lauryl sulfate 15.00
4. Potassium tripolyphosphate 2.50
5. Sodium fluoride 1.00
6. Glycerol (solvent) 250.00
7. Acrylic acid, 0.1% in glycerol 0.10
(monomer)
8. GRAPHTOL GREEN 5884-2 (a phthalo- 0.10
cyanine CI pigment Green #7)
9. Ferrous ammonium sulfate, 0.01
0.1% solution
(Items 6, 7, 8 and 9 are blended together as a
premix.)
10. Polyacrylic acid, 1% solution 0.10
(prepolymer)
11. Peppermint oil 20.00
12. Hydrogen peroxide, 0.1% solution 0.01
4
-13-
Ingredients 1 - 5 (a11 solids) were blended together
until a uniform mix was obtained. This mixture was
then poured with continuous stirring to the glycerol
premix of ingredients 6 - 9 and the resulting blend
mixed again to a uniform paste. The polyacrylic
acid was then added, followed by the peppermint oil,
and the paste blended until smooth. Hydrogen
peroxide was added and the paste was mixed again,
the resulting paste being ready for use.
The bristle part of the toothbrush was
dipped directly into the toothpaste and lifted up.
The amount of paste on the brush was adjusted by
controlling the depth the bristles sink into the
paste. The paste was then air dried.
EXAMPLE 2
Composition by Weight
Parts
1. Calcium carbonate 500.00
2. Sodium hydrogen carbonate 20.00
3. Sodium lauryl sulfate 15.00
4. Potassium tripolyphosphate 2.50
5. Sodium fluoride 1.00
6. Glycerol 250.00
7. Acrylic acid, 0.1% in glycerol 0.10
8. GRAPHTOL GREEN 585H-2 (a phthalo- 0.10
cyanine CI pigment Gzeen #~)
9. Ferrous ammonium sulfate, 0.01
O.I% solution
(Items
6,
7,
8
and
9
are
blended
together
as
a
premix
.
)
10.Polyacrylic acid, 1%~solution , 0.10
11.Spearmint oil 20.00
12.Hydrogen peroxide, 0.1% solution 0.01
The formulation in Example 2 was made exactly the
A
~~~'6~d~
-14-
same as in Example 1, the only difference being that
spearmint oil was substituted for the peppermint
oil. The paste was applied to the brush also by the
same method.
EXAMPLE 3
Combosition
Parts
by
Weight
1. Calcium carbonate 500.00
2. Sodium hydrogen carbonate 20.00
3. Sodium lauryl sulfate 15.00
4. Potassium tripolyphosphate 2.50
5. Sodium fluoride 1.00
6. Glycerol 250.00
7. Acrylic acid, 0.1% in glycerol 0.10
8. GRAPHTOL GREEN 5884-2 (a phthalo-0.10
cyanine CI pigment Green #7)
9. Ferrous ammonium sulfate, 0.01
0.1% solution
(Items 6, 7, 8 and 9 are blended
together as a
premix.)
10. Polyacrylic acid, to solution 0.10
11. Peppermint oil 20.00
12. Hydrogen peroxide, 0.1% solution0.01
13. Deionized water 80.90
Example 3 was made exactly as Example 1 but after
the first 12 ingredients were blended, water was
slowly added with continuous mixing, the resulting
mix blended to a smooth consistency. The bristles
were dipped into the formulation and allowed to dry.
EXAMPLE 4
Composition Parts by Weight
1. Calcium carbonate 500.00
2. Sodium hydrogen carbonate 20.00
. ;.
y:
~! ~x
-15-
3. Sodium lauryl sulfate 15.00
4. Potassium tripolyphosphate 2.50
5. Sodium fluoride 1.00
6. Glycerol 250.00
7. Acrylic acid, O.lo in glycerol 0.10
8. GRAPHTOL GREEN 5854-2 (a phthalo-0.10
cyanine CI pigment Green #7)
9. Ferrous ammonium sulfate, 0.01
0.1% solution
(Items together as
6, a
7,
8
and
9
are
blended
premix
.
)
10.Polyacrylic acid, 1% solution 0.10
11.Spearmint oil 20.00
12.Hydrogen peroxide, 0.1% solution0.01
13.Deionized water 80.90
Example 4 was made the same way as Example 3 except
for the substitution of spearmint oil for peppermint
oil. The bristles were dipped into the paste and
were ready for packing when dry.
Where the toothpaste is applied to the
bristles in two coats, the prime coat consists
basically of the flavoring and the prepolymer,
whereas the top coat consists of the monomer,
catalyst, graft initiator, pigment and other
auxiliary excipients. The desired amount of flavor
is mixed with.the prepolymer and applied to the
bristles by dipping, then curing at 200°F for 4-5
minutes. The desired amounts of each filler, namely
calcium carbonate, sodium hydrogen carbonate, sodium
lauryl sulfate and potassium tripolyphosphate are
combined in a container and mixed until a uniform
mix is obtained. A solution of the pigment is
prepared, added to the uniform mix, and mixed until
~~s~~
-16-
a uniform blend is obtained. The desired amounts of
the monomer, graft initiator and catalyst are then
added to the blend and the contents are mixed well.
The prepared formulation may then be applied as a
top coat over the prime coat by dipping the already
flavor-treated toothbrush into the top coat and
curing at 300°F for 2 minutes.
The following example illustrates a
formulation which may be used in the invention.
EXAMPLE 5
Composition
Parts
by
Weiaht
Prime
ADDlication
1. Polyvinyl alcohol 523
8% solution in water 200.00
2. Peppermint (polarome) 30.00
Ton Application
3. Calcium carbonate 1000.00
4. Sodium hydrogen carbonate 50.00
5. Sodium lauryl sulfate 34.00
6. Potassium tripolyphosphate 5.00
7. Deionized water 162.00
8. Mx 439 PLYACERT GREEN (a mixture 0.20
of FD&C Blue #1 and FD&C Yellow
#5)
9. Glycerol 500.00
10. Acrylic acid, 0.1% in glycerol 0.20
11. Ferrous ammonium sulfate, 0.02
0.1% solution
12. Hydrogen peroxide, 0.1% solution 0.02
Ingredient 1 was prepared by adding small increments
of polyvinyl alcohol to deionized water with
continuous stirring until all particles were wetted
out. The solution was heated to 185°F - 205°F (85°C
- 96°C~ for 30 minutes and then allowed to cool to
WO 95/13412 PCT/US94113208
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room temperature. The peppermint was then added to
this solution, mixed and applied as a prime coat to
the bristles by dipping. The product was then cured
at 200°F for 4-5 minutes. Next, ingredients 3, 4,
and 6 were blended together until a uniform mix
was obtained (Part A). Ingredients 7 and 8 were
mixed well, ingredient 9 was added, and the contents
mixed again (Part B) . Part B was then mixed into
Part A until a uniform blend was obtained (Part C).
Ingredients 10, 11 and 12 were then added to Part C
and mixed well for 1-2 minutes. The formulation
thus prepared was ready to use as a top coat over
the prime coat containing the flavor. This top coat
was applied to the already treated bristles by
dipping. The product was then cured at 300°F for 2
minutes.
It should be understood that the preferred
embodiments and examples described are for
illustrative purposes only and are not to be
construed as limiting the scope of the present
invention which is properly delineated only in the
appended claims.
