Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FILAMENT FOR AN ORAL CARE IMPLEMENT AND ORAL CARE IMPLEMENT
FIELD OF THE INVENTION
The present disclosure is concerned with a filament for an oral care
implement, the filament
having a longitudinal axis and a substantially cross-shaped cross-sectional
area extending in a plane
substantially perpendicular to the longitudinal axis. The present disclosure
is further concerned
with a tuft and a head for an oral care implement and an oral care implement
comprising such head.
BACKGROUND OF THE INVENTION
Tufts composed of a plurality of filaments for oral care implements, like
manual and
powered toothbrushes, are well known in the art. Generally, the tufts are
attached to a bristle carrier
of a head intended for insertion into a user's oral cavity. A grip handle is
usually attached to the
head, which handle is held by the user during brushing. The head is either
permanently connected
or repeatedly attachable to and detachable from the handle.
In order to clean teeth effectively, appropriate contact pressure has to be
provided between
the free ends of the filaments and the teeth. Generally, the contact pressure
depends on the bending
stiffness and the displacement of the filaments, while the bending stiffness
of a single filament
depends on its length and cross sectional area. Usually, filaments with
greater length show lower
bending stiffness as compared to shorter filaments. However, relatively thin
filaments tend to flex
away easily and the relatively low bending stiffness results in reduced plaque
removal efficiency
on teeth surfaces, as well as in less interdental penetrations properties and
cleaning performance.
In order to compensate said reduction in bending stiffness of longer
filaments, the size of the cross
sectional area of a filament could be increased. However, relatively thick
filaments may create an
unpleasant brushing sensation and tend to injure the gums in the oral cavity.
In addition, thicker
filaments may show reduced bend recovery and usage of said filaments may
generate a worn-out
impression of the tuft pattern after a relatively short time of use.
Further, filaments having a profile along their length extension resulting in
a non-circular
cross sectional area, e.g. a polygonal- or a cross-shaped cross sectional
area, are also known in the
art. Such filaments should improve cleaning properties of oral care implements
during normal use.
2
In particular, the profiled edges should provide a stronger scraping action
during a brushing
process to improve removal of plaque and other residuals on the teeth
surfaces.
While toothbrushes comprising these types of filaments clean the outer buccal
face of teeth
adequately, they are generally not as well suited to provide adequate removal
of plaque and debris
from the interproximal areas and other hard to reach areas of the mouth since
penetration into
interdental spaces is still relatively difficult. Furthermore, during
manufacturing processes and
during brushing actions cross-shaped filaments/bristles can easily catch
amongst themselves which
results in a worn-out appearance of the toothbrush. Additionally, these
filaments do not provide
sufficient capillary effects to remove plaque and debris from the teeth and
gum surfaces during
brushing.
It is an object of the present disclosure to provide a filament, a tuft and a
head for an oral
care implement which overcomes at least one of the above-mentioned drawbacks.
It is also an
object of the present disclosure to provide an oral care implement comprising
such head.
SUMMARY OF THE INVENTION
In accordance with one aspect, a filament for an oral care implement is
provided, the
filament having a longitudinal axis and a substantially cross-shaped cross-
sectional area extending
in a plane substantially perpendicular to the longitudinal axis, the cross-
shaped cross-sectional area
having four projections and four channels, the projections and channels being
arranged in an
alternating manner, the cross-sectional area having an outer diameter, and
each channel having a
concave curvature formed by neighboring and converging projections, the
concave curvature
having a radius, wherein the radius is within a range from about 0.015 mm to
about 0.12 mm, and
the ratio of the outer diameter to the radius is within a range from about 2.5
to about 12.
In accordance with one aspect, a tuft and a head for an oral care implement
are provided
that comprises such filament.
In accordance with one aspect an oral care implement is provided that
comprises such head.
In accordance with one aspect, there is provided filament for an oral care
implement , the
filament having a longitudinal axis and a substantially cross-shaped cross-
sectional area extending
in a plane substantially perpendicular to the longitudinal axis, the cross-
shaped cross-sectional area
having four projections and four channels, the projections and channels being
arranged in an
Date Recue/Date Received 2020-08-19
2a
alternating manner, the cross-sectional area having an outer diameter, and
each channel having a
concave curvature formed by neighboring and converging projections, the
concave curvature
having a radius, wherein the radius is within a range from about 0.015 mm to
about 0.12 mm, the
outer diameter is within a range from 0.22 mm to 0.40 mm and the ratio of the
outer diameter to the
radius is within a range from about 2.5 to about 12.
BRIEF DESCRIPTION OF THE DRAWINGS
Date Recue/Date Received 2020-08-19
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The invention is described in more detail below with reference to various
embodiments and
figures, wherein:
Fig. 1 shows a schematic perspective view of an oral care implement comprising
a plurality
of filaments according to the present disclosure;
Fig. 2 shows a schematic cross-sectional view of the filament of Fig. 1;
Fig. 3 shows a schematic cross-sectional view of a filament according to the
state of the
art;
Fig. 4 shows a schematic cross-sectional view of an example embodiment of a
tuft;
Fig. 5 shows a schematic cross-sectional view of a tuft according to a first
comparative
example embodiment;
Fig. 6 shows a schematic cross-sectional view of a tuft according to a second
comparative
example embodiment;
Fig. 7 shows a diagram in which brushing results of filaments according to
Fig. 2 are
compared with brushing results of filaments according to two comparative
example embodiments;
Fig. 8 shows a diagram in which "slurry uptake mass" of filaments according to
Fig. 2 is
compared with "slurry uptake mass" of filaments according to two comparative
example
embodiments;
Fig. 9 shows a diagram in which "slurry uptake speed" of filaments according
to Fig. 2 is
compared with "slurry uptake speed" of filaments according to two comparative
example
embodiments; and
Fig. 10 shows a schematic cross-sectional view of a diamond-shaped filament
according to
the state of the art.
DETAILED DESCRIPTION OF THE INVENTION
The filament according to the present disclosure has a longitudinal axis which
is defined
by the main extension of the filament. In the following, the extension of the
filament along its
longitudinal axis may also be referred to as the "longitudinal extension of
the filament". The
filament has a cross-sectional area which extends in a plane that is
substantially perpendicular to
the longitudinal axis. The shape of said cross-sectional area is cross-shaped.
The cross-shaped
cross-sectional area comprises four projections and four channels wherein the
projections and
channels are arranged in an alternating manner. Two neighboring projections,
i.e. two neighboring
side lateral edges of said projections converge at the bottom of a channel and
define a "converging
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region". The neighboring projections converge in said converging region in a
manner that a
concave curvature, i.e. with an inwardly curved radius is formed at the bottom
of the channel.
The cross-shaped cross sectional area has an outer diameter. In the context of
the present
disclosure the outer diameter is defined by the length of a straight line that
passes through the
center of the filament's cross-sectional area and whose endpoints lie on the
most outer
circumference of the cross-sectional area. In other words, the cross-shaped
cross-sectional area
has an imaginary outer circumference in the form of a circle (i.e. outer
envelope circle), and the
outer diameter is defined as the longest straight line segment of the circle
passing through the center
of the circle.
According to the present disclosure, the radius of the concave curvature at
the bottom of
the channel is within a range from about 0.015 mm to about 0.12 mm, and the
ratio of the outer
diameter to the radius is within a range from about 2.5 to about 12.
Alternatively, the radius may
be within a range from about 0.03 mm to about 0.10 mm, and the ratio of the
outer diameter to the
radius may be within a range from about 2.7 to about 9.
The outer diameter may be within a range from about 0.15 mm to about 0.40 mm,
or from
about 0.19 mm to about 0.38 mm, or the outer diameter may be within a range
from about 0.22
mm to about 0.35 mm, or from about 0.24 mm to about 0.31 mm.
Surprisingly, it has been found out that such filament geometry provides
improved cleaning
performance while maintaining brush comfort in the mouth. In addition, it has
been found out that
such geometry helps to reduce the appearance of filament/tuft wear since there
is less likelihood
that the filaments get caught during brushing. Further, the manufacturability
of such filaments
during a toothbrush manufacturing process is improved.
A radius of the curvature at the bottom of the channel within a range from
about 0.015 mm
to about 0.12 mm, or from about 0.03 mm to about 0.10 mm is relatively large
as compared to
standard cross-shaped filaments.
Each projection of the cross-shaped cross-sectional area comprises two outer
lateral edges
along the filament's longitudinal extension. These lateral edges may generate
relatively high
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concentrated stress on the tooth surfaces to disrupt and remove plaque. The
outer edges can
provide a scraping effect so that plaque and other debris get loosened more
effectively. Due to the
relatively large radius at the bottom of the channel, the projections are
provided with increased
stiffness/stability to loosen/remove plaque from the teeth surfaces more
easily/effectively. The
5 .. channels can then capture the disrupted plaque and may move it away from
the teeth.
Further, due to the specific geometry of the radius, the cannels may
facilitate that the
filaments can be packed within a tuft with less density resulting in even more
dentifrice/toothpaste
retaining at/adhering to the filaments for a longer period of time during a
tooth brushing process
and may avoid that the dentifrice spread away which may result in an improved
overall brushing
process. In other words, toothpaste can be better received in the cannels and,
upon cleaning contact
with the teeth, directly delivered, whereby a greater polishing effect is
achieved, which is desirable,
in particular for removal of tooth discoloration.
Further, the decreased filament density within a tuft may provide an improved
capillary
action which may enable the dentifrice to flow towards the tip/free end of the
filament and, thus,
may make the dentifrice better available to the teeth and gums during
brushing. In addition, that
capillary effect may further facilitate the uptake of plaque to improve the
overall cleaning
performance/efficiency during tooth brushing.
As shown in Fig. 7 and further explained below, a tuft comprising a plurality
of filaments
according to the present disclosure provides improved plaque removal from the
buccal, lingual,
occlusal and interdental surfaces as well as along the gumline as compared to
a tuft of circular or
conventional cross-shaped filaments.
Moreover, in the past it has been observed that conventional cross-shaped
filaments (e.g.
as shown in Fig. 3 and further described below) have the disadvantage that
these type of filaments
can easily catch amongst themselves, both during manufacturing and brushing.
However, it has
been surprisingly found out that the specific geometry/contour of the outer
surface of the filament
according to the present disclosure allows for improved manufacturability
since there is significant
less likelihood that the filaments get caught when a plurality of said
filaments is combined to form
one tuft during a so-called "picking process".
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Further, due to the relatively large radius within a range from about 0.015 mm
to about 0.12
mm, or from about 0.03 mm to about 0.10 mm, less filament damage occur during
the brush
manufacturing process, e.g. when the filaments get picked and fixed on the
mounting surface of
the brush head during a stapling or hot tufting process. In the past, it has
been observed that a
relatively high number of conventional cross-shaped filaments get damaged
during the picking
process, in particular projections may break away from the filament or the
filament gets spliced in
the converging region at the bottom of a channel. Spliced filaments can
provide relatively sharp
edges which may harm/injure the oral tissue during brushing.
The projections of the cross-shaped filament may taper radially off in an
outward direction,
i.e. in a direction away from the center of the cross-sectional area and
towards the outer
circumference. Such tapered projections may assure access to narrow spaces and
other hard to
reach areas and may be able to penetrate into/enter interdental areas even
more deeply and
effectively. Since the bending stiffness of a cross-shaped filament is higher
as compared to a
circular-shaped filament made of the same amount of material, the higher
bending stiffness may
force the filament's projections to slide into the interdental areas more
easily.
The projections may taper radially outwards by an angle within a range from
about 6' to
about 25 or by an angle within a range from about 8 to about 20 .
Surprisingly, it has been found
out that such tapering allows for optimal interdental penetration properties.
Additionally, such
filament can be more easily bundled in a tuft without catching on contours of
adjacent filaments.
Each projection has a width extension extending between two opposite lateral
edges. Said
width extension may be within a range from about 6% to about 15% or from about
8% to about
12% of the outer diameter of the filament. Said width extension may be within
a range from about
0.016 mm to about 0.041 mm, or from about 0.021 mm to about 0.033 mm. Such
filaments may
adapt to the teeth contour in a better manner and penetrate into the
interdental spaces more easily
to remove plaque and debris more completely.
The filament may be a substantially cylindrical filament, i.e. the filament
may have a
substantially cylindrical outer lateral surface. In other words, the shape and
size of the cross-
sectional area of the filament along its longitudinal axis may not vary
substantially, i.e. the shape
and size of the cross-sectional area may be substantially constant over the
longitudinal extension
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of the filament. In the context of this disclosure the term "outer lateral
surface of a filament" means
any outer face or surface of the filament on its sides. This type of filament
may provide increased
bending stiffness as compared to tapered filaments. A higher bending stiffness
may facilitate the
filament to penetrate into interdental gaps/spaces. Further, cylindrical
filaments are generally
.. slowly worn away which may provide longer lifetime of the filaments.
The cylindrical filament may have a substantially end-rounded tip/free end to
provide
gentle cleaning properties. End-rounded tips may avoid that gums get injured
during brushing.
Within the context of this disclosure, end-rounded filaments would still fall
under the definition of
a substantially cylindrical filament.
Alternatively, the filament may comprise along its longitudinal axis a
substantially
cylindrical portion and a tapered portion, the tapered portion tapers in the
longitudinal direction
towards a free end of the filament, and the cylindrical portion has a cross-
sectional area according
to the present disclosure. In other words, the filament may be a tapered
filament having a pointed
tip. Tapered filaments may achieve optimal penetration into areas between two
teeth as well as
into gingival pockets during brushing and may provide improved cleaning
properties. The tapered
filament may have an overall length extending above the mounting surface
within a range from
about 8 mm to about 16 mm, optionally about 12.5 mm, and a tapered portion
within a range from
.. about 5 mm to about 10 mm measured from the tip of the filament. The
pointed tip may be needle
shaped, may comprise a split or a feathered end. The tapering portion may be
produced by a
chemical and/or mechanical tapering process.
The filament may be made of polyamide, e.g. nylon, with or without an abrasive
such as
.. kaolin clay, polybutylene terephtalate (PBT) with or without an abrasive
such as kaolin clay and/or
of polyamide indicator material, e.g. nylon indicator material, colored at the
outer surface. The
coloring on the polyamide indicator material may be slowly worn away as the
filament is used over
time to indicate the extent to which the filament is worn.
The filament may comprise at least two segments of different materials. At
least one
segment may comprise a thermoplastic elastomer material (TPE) and at least one
segment may
comprise polyamide, e.g. nylon, with or without an abrasive such as kaolin
clay, polybutylene
terephtalate (PBT) with or without an abrasive such as kaolin clay or a
polyamide indicator
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material, e.g. a nylon indicator material, colored at the outer surface. These
at least two segments
may be arranged in a side-by-side structure or in a core-sheath structure
which may result in
reduced stiffness of the overall filament. A core-sheath structure with an
inner/core segment
comprising a harder material, e.g. polyamide or PBT, and with an outer/sheath
segment
surrounding the core segment and comprising a softer material, e.g. TPE, may
provide the filament
with a relatively soft outer lateral surface which may result in gentle
cleaning properties.
The filament may comprise a component selected from fluoride, zinc, strontium
salts,
flavor, silica, pyrophosphate, hydrogen peroxide, potassium nitrate or
combinations thereof. For
example, fluoride may provide a mineralization effect and, thus, may prevent
tooth decay. Zinc
may strengthen the immune system of the user. Hydrogen peroxide may
bleach/whiten the teeth.
Silica may have an abrasive effect to remove dental plaque and debris more
effectively.
Pyrophosphate may inhibit the formation of new plaque, tartar and dental
calculus along the gum
line. A filaments comprising pyrophosphate may offer lasting protection
against inflammations of
the gums and mucous membrane of the mouth.
If a plurality of such filaments are bundled together to form a tuft, they may
be arranged in
a manner that filaments at the tuft's outer lateral surface may comprise
pyrophosphate to inhibit
the formation of plaque, tartar and dental calculus along the gum line whereas
filaments arranged
in the center of the tuft may comprise fluoride to mineralize the teeth during
a brushing process.
At least one of the components listed above may be coated onto a sheath, i.e.
onto an outer
segment of a filament. In other words, at least some of the filaments of the
tuft may comprise a
core-sheath structure wherein the inner/core segment may comprise TPE,
polyamide or PBT, and
the outer/sheath segment may comprise at least one of the components listed
above. Such core-
sheath structure may make the component(s) directly available to the teeth in
a relatively high
concentration, i.e. the component(s) may be in direct contact with the teeth
during brushing.
Alternatively, at least one of the components listed above may be co-extruded
with TPE,
polyamide, e.g. nylon, and/or PBT. Such embodiments may make the component(s)
gradually
available to the teeth when the filament material is slowly worn away during
use.
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A plurality of filaments according to any of the embodiments described above
may be
bundled together to form a tuft attached to an oral care implement. The oral
care implement may
be a toothbrush comprising a handle and a head. The head extends from the
handle and may be
either repeatedly attachable to and detachable from the handle or the head may
be non-detachably
connected to the handle. The toothbrush may be an electrical or a manual
toothbrush.
The head may comprise a bristle carrier having a substantially circular or
oval shape. Such
a bristle carrier may be provided for an electrical toothbrush which may
perform a rotational
oscillation movement. The bristle carrier of an electrical toothbrush can be
driven to rotate about
and to move axially along an axis of movement in an oscillating manner,
wherein such axis of
movement may extend substantially perpendicular to the plane defined by the
upper top surface of
the bristle carrier. One or more tuft(s) comprising a plurality of filaments
according to the present
disclosure may be attached to the bristle carrier. Said tuft(s) may allow the
filaments projections
to penetrate into interdental areas and hard to reach regions more easily
during the rotational
oscillation movement of the head which may provide further improved cleaning
properties of the
head. Plaque and other residues may be loosened by the oscillating action of
the filaments being
substantially perpendicular to the tooth surfaces, whereas the rotational
movement may sweep the
plaque and further residues away.
The tuft according to the present disclosure may have a packing factor within
a range from
about 40% to about 60%, or from about 45% to about 55%, or about 45%.
Surprisingly, it has
been found out that filaments according to the present disclosure may allow
for such a relatively
low packing factor of the filaments within the tuft as gaps between two
adjacent filaments can be
maximized. In the context of this disclosure the term "packing factor.' is
defined as the sum total
of the transverse cross-sectional areas of the filaments in the tuft hole
divided by the transverse
cross-sectional area of the tuft hole. In embodiments where anchors, such as
staples, are used to
mount the tuft within the tuft hole, the area of the anchoring means is
excluded from the transverse
cross-sectional area of the tuft hole. A packing factor of about 45% opens up
a specific void
volume within the tuft while the filaments have still contact to each other
along a portion of the
outer lateral surface. The void volume may deliver more toothpaste to the
tooth brushing process
and the toothpaste can interact with the teeth for a longer period of time
which contributes to
improved tooth brushing effects. In addition, the void volume, i.e. the space
between filaments,
enables increased uptake of loosened plaque due to improved capillary action.
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Surprisingly it has been found out that this void volume can be achieved by
using filaments
according to the present disclosure. It has been found out that it is
important that the filaments
open up a void area while still having contact to each other. In order to
produce a toothbrush that
5 .. is compliant with regulatory requirements and appreciated by the consumer
regarding the overall
appearance, typically a high packing factor (about 70% to about 80% for round
filaments; about
80% for diamond-shaped filaments; about 89% for trilobal filaments) is needed.
With respect to
toothbrushes manufactured by a stapling process, a packing factor lower than
about 70% results in
insufficiently compressed filaments within the tuft hole and, thus, provides
insufficient tuft
10 retention. Consequently, regulatory requirements are not met in case
round filaments are provided
with a packing factor lower than about 70%. For hot tufted toothbrushes, a
packing factor lower
than about 70% would allow plastic melt entering into the tuft during the over
molding process as
the pressure of the melt pushes the filaments of the tuft to one side until
the filaments have contact
to each other. So-called polyspikes are thereby formed which may injure/harm
the gums and, thus
resulting in unsafe products. Beside regulatory and safety aspects a low
packed tuft of round
filaments would have a "wild" and destroyed appearance and would not be
accepted by the
consumer. However, with the usage of filaments according to the present
disclosure a low packing
factor can be achieved for compliant and safe products having an acceptable
overall appearance.
A relatively low packing factor within a range from about 40% to about 60%, or
from about
45% to about 55%, or about 45% may provide improved brushing effectiveness,
i.e. better removal
of plaque and debris from the teeth's surface and gums due to improved
capillary effects. These
capillary effects may enable the dentifrice to flow towards the tip/free end
of the filaments and,
thus, may make the dentifrice more available to the teeth and gums during
brushing. At the same
time uptake of plaque and debris away from the teeth and gum surfaces is
improved.
Further, due to the cross-shaped geometry of the filament, each single
filament is stiffer
than a circular shaped filament, when made of the same amount of material.
However, due to the
low packing factor within a range from about 40% to about 60%, or from about
45% to about 55%,
or about 45%, the stiffness of the overall tuft made of filaments according to
the present disclosure
is reduced as compared to a tuft of circular shaped filaments. This results in
improved sensory
experience during brushing while providing increased cleaning efficiency.
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The at least one tuft attached to the head for an oral care implement may have
a longitudinal
axis and a cross-sectional area which extends in a plane that is perpendicular
to said longitudinal
axis. The plurality of filaments may be arranged in a manner that the cross-
sectional area of the
tuft has a scaled up shape of the respective shape of each individual filament
which makes up the
tuft. In other words, the tuft is a scaled up version of its filaments, i.e.
the shape of the cross-
sectional area of the tuft may have substantially the same cross-shaped cross-
sectional area as each
individual filament but in a larger size. The shape of the cross-sectional
area of the tuft may
correspond to the shape of the cross-sectional area of its filaments. In the
context of this disclosure
the term "cross-sectional area having a scaled up shape" means a cross-
sectional area comprising
the same shape but in increased size. In other words, the type of shape may be
the same but the
size of the cross-sectional area is different, i.e. increased. Any gaps,
irregularities, reliefs or slots
which may be present between two adjacent individual filaments at the outer
circumference of the
cross-sectional area of the tuft do not contribute to the substantial shape of
said cross-sectional area
and are, thus, to be neglected.
Such tuft may provide increased cleaning properties. The specific
shape/geometry of the
individual filaments has specific cleaning properties which differ from the
properties of regular
filaments with a circular or conventional cross-shaped cross-sectional area.
These specific
cleaning properties may be enhanced by arranging the filaments in a manner so
that they form a
.. cross-sectional shape of the overall tuft which is a scaled up version of
the cross-sectional shape
of each individual filament. In addition, as the specific geometry of each
single filament may be
generally not visible to the user, the tuft in accordance with the present
disclosure may
communicate the respective geometry to the user and, thus, the corresponding
cleaning properties
of the filaments which make up said tuft.
As the filaments and the tuft, respectively, have each a cross-sectional area
with a non-
circular shape, the filaments as well as the overall tuft may provide
anisotropic bending stiffness
properties during a brushing process. In case a given contact pressure is
applied to the free end of
the filaments/tuft the amount of deflection/displacement of the filaments/tuft
depends on the
diameter/radius of the filaments/tuft. The smaller the diameter/radius, the
higher is the
deflection/displacement of the free end of the filaments/tuft, and vice versa,
the larger the
diameter/radius, the smaller is the deflection/displacement of the free end of
the filaments/tuft. The
tuft may be arranged on the mounting surface of the head in a manner that
higher bending stiffness
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is provided in a direction where higher cleaning forces may be needed. Lower
bending stiffness
may be provided in a direction where gentle cleaning forces or a massaging
effect may be required.
A head for an oral care implement in accordance with the present disclosure
may comprise
a bristle carrier being provided with at least one tuft hole, e.g. a blind-end
bore. A tuft comprising
a plurality of filaments according to the present disclosure may be
fixed/anchored in said tuft hole
by a stapling process/anchor tufting method. This means, that the filaments of
the tuft are
bent/folded around an anchor, e.g. an anchor wire or anchor plate, for example
made of metal, in
a substantially U-shaped manner. The filaments together with the anchor are
pushed into the tuft
hole so that the anchor penetrates into opposing side walls of the tuft hole
thereby
anchoring/fixing/fastening the filaments to the bristle carrier. The anchor
may be fixed in opposing
side walls by positive and frictional engagement. In case the tuft hole is a
blind-end bore, the
anchor holds the filaments against a bottom of the bore. In other words, the
anchor may lie over
the U-shaped bend in a substantially perpendicular manner. Since the filaments
of the tuft are bent
around the anchor in a substantially U-shaped configuration, a first limb and
a second limb of each
filament extend from the bristle carrier in a filament direction. Filament
types which can be
used/are suitable for usage in a stapling process are also called "two-sided
filaments". Heads for
oral care implements which are manufactured by a stapling process can be
provided in a relatively
low-cost and time-efficient manner. Due to the improved geometry of the
filament according to
the present disclosure, fewer filaments get damaged, e.g. by slicing, when the
filaments get picked
and fixed on the mounting surface of the brush head during the stapling
process. Further, fewer
filaments get caught on the outer surface of a neighboring filament when a
plurality of filaments
are picked to form one tuft.
Alternatively, the at least one tuft may be attached/secured to the head by
means of a hot
tufting process. One method of manufacturing the head of an oral care
implement may comprise
the following steps: Firstly, the at least one tuft may be formed by providing
a desired amount of
filaments according to the present disclosure. Secondly, the tuft may be
placed into a mold cavity
so that ends of the filaments which are supposed to be attached to the head
extend into said cavity.
Thirdly, the head or an oral care implement body comprising the head and the
handle may be
formed around the ends of the filaments extending into the mold cavity by an
injection molding
process, thereby anchoring the at least one tuft in the head. Alternatively,
the tuft may be anchored
by forming a first part of the head ¨ a so called "sealplate" ¨ around the
ends of the filaments
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extending into the mold cavity by an injection molding process before the
remaining part of the
oral care implement may be formed. Before starting the injection molding
process, the ends of the
at least one tuft extending into the mold cavity may be optionally melted or
fusion-bonded to join
the filaments together in a fused mass or ball so that the fused masses or
balls are located within
the cavity. The at least one tuft may be held in the mold cavity by a mold bar
having blind holes
that correspond to the desired position of the tuft on the finished head of
the oral care implement.
In other words, the filaments of the at least one tuft attached to the head by
means of a hot tufting
process may be not doubled over a middle portion along their length and may be
not mounted in
the head by using an anchor/staple. The at least one tuft may be mounted on
the head by means of
an anchor-free tufting process. A hot tufting manufacturing process allows for
complex tuft
geometries. For example, the tuft may have a specific topography/geometry at
its free end, i.e. at
its upper top surface, which may be shaped to optimally adapt to the teeth's
contour and to further
enhance interdental penetration. For example, the topography may be chamfered
or rounded in
one or two directions, pointed or may be formed linear, concave or convex. Due
to the improved
geometry of the filament according to the present disclosure, fewer filaments
get damaged, e.g. by
slicing, when the filaments get picked and fixed on the mounting surface of
the brush head during
the hot-tufting process. Further, fewer filaments get caught on the outer
surface of a neighboring
filament when a plurality of filaments are picked to form one tuft.
The following is a non-limiting discussion of example embodiments of oral care
implements and parts thereof in accordance with the present disclosure, where
reference to the
Figures is made.
Fig. 1 shows a perspective top-down view of an oral care implement 10 which
could be a
manual or an electrical toothbrush 10 comprising a handle 12 and a head 14
extending from the
handle 12 in a longitudinal direction. The head 14 has a proximal end 41 close
to the handle 12
and a distal end 40 furthest away from the handle 12, i.e. opposite the
proximal end 41. The head
14 may have substantially the shape of an oval with a length extension 52 and
a width extension
51 substantially perpendicular to the length extension 52. A plurality of
tufts 16 having a plurality
of filaments 20 in accordance with the present disclosure may be secured to
the head 14 by means
of a hot tufting or stapling process. The tufts 16 may extend from a mounting
surface 18 of the
head 14 in a substantially orthogonal manner.
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The tufts 16 as illustrated in Fig. I comprise a plurality of end-rounded
filaments 20, one
of them being shown in Fig. 2. Alternatively, the filaments 20 may be tapered
filaments comprising
along the longitudinal axis a substantially cylindrical portion and a tapered
portion. The tapered
portion tapers towards the free end of the filament 20, and the cylindrical
portion has a cross-
sectional area 22 according to the present disclosure. The plurality of
filaments 20 is arranged in
a manner that the tufts 16 have a cross-sectional area 32 with a scaled up
shape of the shape of
each individual filament 20. In other words, the shape of the cross-sectional
area 32 of the tufts 16
corresponds to the shape of the cross-sectional area 22 of each individual
filament 20. The tufts
16 may have a packing factor within a range from about 40% to about 60%, or
from about 45% to
.. about 55%. The "packing factor" is defined as the total sum of the cross-
sectional areas 22 of the
filaments 20 divided by the cross-sectional area of the tuft hole.
Fig. 2 shows a schematic cross-sectional view of a filament 20 according to
the present
disclosure. The filament 20 has a longitudinal axis and a substantially cross-
shaped cross-sectional
area 22 extending in a plane substantially perpendicular to the longitudinal
axis. The cross-shaped
cross-sectional area 22 has four projections 24 and four channels 26. The
projections 24 and
channels 26 are arranged in an alternating manner. Each projection 24 tapers
in an outward
direction by an angle a within a range from about 6' to about 25 or from
about 8 to about 20n.
The cross-sectional area 22 has an outer diameter 28 passing through the
center 36 of the
filament's cross-sectional area 22. The endpoints of the outer diameter 28 lie
on the most outer
circumference 38 of the cross-sectional area 22. The outer diameter 28 has a
length extension
within a range from about 0.15 mm to about 0.40 mm, from about 0.19 mm to
about 0.38 mm,
from about 0.22 mm to about 0.35 mm, or from about 0.24 mm to about 0.31 mm.
Further, each channel 26 has a concave curvature 34, i.e. a curvature being
curved inwardly
towards the center 36 of the cross-sectional area 22. The concave curvature 34
is formed at the
bottom of each channel 26 by two neighboring and converging projections 24.
The concave
curvature 34 has a radius 30 which is in a range from about 0.015 mm to about
0.12 mm, and the
ratio of the outer diameter 28 to the radius 30 is within a range from about
2.5 to about 12.
Alternatively, the radius 30 is within a range from about 0.03 mm to about
0.10 mm, and the ratio
of the outer diameter 28 to the radius 30 is within a range from about 2.7 to
about 9.
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Each projection has a width extension 42 extending between two opposite
lateral edges 44,
and the width extension 42 is defined in a range from about 6% to about 15%,
or from about 8%
to about 12% of the outer diameter 28 of the filament 20. For example, the
width extension 42
may be within a range from about 0.016 mm to about 0.041 mm, or from about
0.021 mm to about
5 0.033 mm. Each projection 24 may be end-rounded having a curvature with a
radius 46 of about
0.02 mm.
Fig. 3 shows a schematic cross-sectional view of a cross-shaped filament 54
according to
the state of the art. Filament 54 comprises the following dimensions:
10 Outer diameter 56: 0.295 mm
Radius 58 of the concave curvature: 0.01 mm
Ratio outer diameter 56 to radius 58 of the concave curvature: 29.5
Tapering of the projections a: 15
Radius 60 of the curvature of the end-rounded projections: 0.02 mm
15 Width extension 62 at the outermost portion of each projection before
the end-rounding of
the projection starts: 0.04 mm
Inner diameter 64: 0.1 mm.
Fig. 4 shows a schematic cross-sectional view of example embodiment 1 of a
tuft 66
according to the present disclosure. Tuft 66 has a packing factor of about
49%. The filaments 68
of tuft 66 have the following dimensions:
Outer diameter 28: 0.309 mm
Radius 30 of the concave curvature: 0.06 mm
Ratio outer diameter 28 to radius 30 of the concave curvature: 5.15
Tapering of the projections a: 10
Radius 46 of the curvature of the end-rounded projections: 0.02 mm
Width extension 42 at the outermost portion of each projection before the end-
rounding of
the projection starts: 0.04 mm
Inner diameter 70: 0.12 mm.
Fig. 5 shows a schematic cross-sectional view of a tuft 72 comprising a
plurality of circular
filaments 74 according to the state of the art. The diameter of filaments 74
is about 0.178 mm (7
mil). Such tuft 72 has a packing factor of about 77% (comparative example 2).
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Fig. 6 shows a schematic cross-sectional view of a tuft 76 comprising a
plurality of
filaments 54 according to Fig. 3. Such tuft 76 has a packing factor of about
58% (comparative
example 3).
COMPARISON EXPERIMENTS
Robot Tests:
The tuft 66 (diameter of the tuft: 1.7 mm) in accordance with Fig. 4
comprising a plurality
of filaments 68 (example embodiment 1), the tuft 72 (diameter of the tuft: 1.7
mm) according to
Fig. 5 comprising a plurality of filaments 74 (comparative example 2), and the
tuft 76 (diameter of
the tuft: 1.7 mm) according to Fig. 6 comprising a plurality of filaments 54
(comparative example
3) were compared with respect to their efficiency of plaque substitute removal
on artificial teeth
(typodonts).
Brushing tests were performed using a robot system KUKA 3 under the following
conditions (cf. Table 1):
Product program upper program lower force power
supply
jaw jaw
All tested products E0 _ IND ELI_ INDI 3 N no
total cleaning time 60 s 60 s
program version 9 11 09 Eng 9.11.09 Eng
SYSTEC speed 60 60
SYSTEC amplitude x y 20/0 2010
number of moves 3 3
Movement horizontal
used handle mould No! no
Table 1
Fig. 7 shows the amount of plaque substitute removal in % of example
embodiment 1,
comparative example 2 and comparative example 3, each with respect to all
tooth surfaces 78,
buccal surfaces 80, lingual surfaces 82, lingual and buccal surfaces 84,
occlusal surfaces 86, the
gum line 88 and interdental surfaces 90.
Fig. 7 clearly shows that example embodiment 1 provides significant improved
plaque
removal properties with respect all tooth surfaces 78, buccal surfaces 80,
lingual surfaces 82,
lingual and buccal surfaces 84, occlusal surfaces 86, the gum line 88 and
interdental surfaces 90 as
compared to comparative examples 2 and 3. The most significant improvement of
the cleaning
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performance occurred on the occlusal surfaces 86 with an improvement of 22 %
and 9%,
respectively.
Slurry Uptake Tests:
Fig. 8 shows a diagram in which "slurry uptake mass" of a tuft (diameter of
the tuft: 1.7
mm) comprising filaments in accordance with the present disclosure and having
a packing factor
of about 46% (example embodiment 4) is compared with "slurry uptake mass" of a
tuft (diameter
of the tuft: 1.7 mm) comprising diamond shaped filaments (cf. Fig. 10) and
having a packing factor
of about 80% (comparative example 5), and with "slurry uptake mass" of the
tuft 72 according to
comparative example 2.
The filaments of example embodiment 4 have the following dimensions:
Outer diameter: 0.269 mm
Radius of the concave curvature: 0.05 mm
Ratio of outer diameter to radius of the concave curvature: 5.38
Tapering of the projections a: 14
Radius of the curvature of the end-rounded projections: 0.0145 mm
Width extension at the outermost portion of each projection before the end-
rounding of the
projection starts: 0.029 mm
Inner diameter: 0.102 mm
The filaments of comparative example 5 have the following dimensions (Fig.
10):
Longer diagonal length 92: 0.29 mm
Shorter diagonal length 94: 0.214 mm
Fig. 9 shows a diagram in which "slurry uptake speed" of example embodiment 4
is
compared with "slurry uptake speed" of comparative examples 2 and 5.
Test description:
Brush heads comprising tufts according to example embodiment 4 and comparative
examples 2 and 5 were fixed in a horizontal position with filaments pointing
down. A bowl of
toothpaste slurry (toothpaste: water = 1:3) was placed with a scale directly
under the brush heads.
The scale was used to measure the amount of slurry in the bowl. When the test
was started, the
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brushes moved down with 100mm/s and dipped 2mm deep into the slurry. Then the
brushes were
hold for 5s in the toothpaste slurry and pulled out again with 100mm/min. The
force in vertical
direction was measured over time.
Figs. 8 and 9 clearly show that example embodiment 4 provides significant
improved
"slurry uptake" in terms of mass and speed as compared to comparative examples
2 and 5. The
increased void volume within the tuft of example embodiment 4 enables improved
capillary action.
This leads to increased uptake of toothpaste (slurry) so that the toothpaste
interacts/contributes
longer to the tooth brushing process. The tuft of example embodiment 4 can
take-up about 50%
more toothpaste slurry with about 50% higher uptake speed which results in
improved tooth
cleaning effects. In other words, besides delivering more toothpaste to the
tooth brushing process,
the specific void volume within the tuft of example embodiment 4 enables also
increased uptake
of loosened plaque. This results in an overall improved clinical performance
of a toothbrush
comprising cross-shaped filaments according to the present disclosure which
enable a lower
packing factor.
In the context of this disclosure, the term "substantially" refers to an
arrangement of
elements or features that, while in theory would be expected to exhibit exact
correspondence or
behavior, may, in practice embody something slightly less than exact. As such,
the term denotes
the degree by which a quantitative value, measurement or other related
representation may vary
from a stated reference without resulting in a change in the basic function of
the subject matter at
issue.
The dimensions and values disclosed herein are not to be understood as being
strictly
limited to the exact numerical values recited. Instead, unless otherwise
specified, each such
dimension is intended to mean both the recited value and a functionally
equivalent range
surrounding that value. For example, a dimension disclosed as "40 mm" is
intended to mean "about
40 mm."
