Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TUFT AND HEAD FOR AN ORAL CARE IMPLEMENT AND ORAL CARE IMPLEMENT
HELD OF THE INVENTION
The present disclosure is concerned with a tuft for an oral care implement,
the tuft
comprising a plurality of filaments 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 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.
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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 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 tuft for an oral care implement is provided,
the tuft
comprising a plurality of filaments, each 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 manlier, each
channel having a
concave curvature formed by neighboring and converging projections, the
concave curvature
having a radius, wherein the radius of the concave curvature of the channel is
within a range from
about 0.025 mm to about 0.10 mm, and the tuft has a packing factor within a
range from about
40% to about 55%.
In accordance with one aspect, a head for an oral care implement is provided
that comprises
such tuft.
In accordance with one aspect an oral care implement is provided that
comprises such head.
3
In accordance with one aspect, there is provided a tuft for an oral care
implement
comprising a plurality of filaments, each 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, each channel
having a concave curvature formed by neighboring and converging projections,
the concave
curvature having a radius, wherein the radius of the concave curvature of the
channel is within a
range from about 0M25 mm to about 0.10 mm, and the tuft has a packing factor
within a range
from about 40% to about 49%.
BRIEF DESCRIPTION OF THE DRAWINGS
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 having
tufts
comprising a plurality of filaments according to the present disclosure;
Fig. 2 shows a schematic cross-sectional view of one filament of the tuft as
shown in 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 a tuft comprising
filaments according
to Fig. 2 are compared with brushing results of tufts according to two
comparative example
embodiments;
Fig. 8 shows a diagram in which "slurry uptake mass" of a tuft comprising
filaments
according to Fig. 2 is compared with "slurry uptake mass" of tufts according
to two comparative
example embodiments;
Fig. 9 shows a diagram in which "slurry uptake speed" of a tuft comprising
filaments
according to Fig. 2 is compared with "slurry uptake speed" of tufts according
to two comparative
example embodiments; and
Date recu/Date Received 2020-04-20
3a
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 tuft according to the present disclosure comprises a plurality of
filaments. Each
filament of said tuft 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
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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 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 radius of the concave curvature of the channel is within a range from
about 0.025 mm
to about 0.10 mm, or from about 0.03 mm to about 0.08 mm, or from 0.04 mm to
about 0.06 mm.
A radius with such range is relatively large as compared to standard cross-
shaped filaments (cf.
Fig. 3 and as further described below).
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".
Further, due to the relatively large radius at the bottom of the channel, the
filament is
provided with increased stability, and, thus, 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.
Further, due to the specific geometry of the radius of the concave curvature,
the cannels
may facilitate that the filaments can be packed within a tuft with less
density, i.e. with a lower
packing factor. This may result in even more dentifrice/toothpaste retaining
at/adhering to the
filaments for a longer period of time during a tooth brushing process.
Further, the lower tuft density
may avoid that the dentifrice spread away which may result in an improved
overall brushing
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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.
5 The tuft according to the present disclosure has a packing factor within
a range from about
40% to about 55%, or from about 45% to about 50%, or about 49%. Surprisingly,
it has been
found out that cross-shaped filaments having a radius of the concave curvature
of the channel
within a range from about 0.025 mm to about 0.10 mm 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 40% to about 55%,
or from about 45% to
about 50%, or about 49% 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.
In other words, a relatively low packing factor within a range from about 40%
to about
55%, or from about 45% to about 50%, or about 49% 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.
Surprisingly it has been found out that this void volume can be achieved by
using cross-
shaped filaments having a radius of the concave curvature of the channel
within a range from about
0.025 mm to about 0.10 mm. 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 is
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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
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 consumers.
However, with the usage of cross-shaped filaments having a radius of the
concave curvature of the
channel within a range from about 0.025 mm to about 0.10 mm a low packing
factor can be
achieved for compliant and safe products having an acceptable overall
appearance while providing
improved cleaning properties.
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.
Further, due to the specific 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 55%, or from
about 45% to about
50%, or about 49%, the stiffness of the overall tuft made of cross-shaped
filaments having a radius
of the concave curvature of the channel within a range from about 0.025 mm to
about OA 0 mm is
reduced as compared to a tuft of circular shaped filaments. Surprisingly, it
has been found out that
such tuft provides improved sensory experience, i.e. a softer feeling within
the mouth during
brushing while providing increased cleaning efficiency.
The cross-shaped cross sectional area of each filament 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
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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.
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.
The ratio of the outer diameter to the radius of the curvature of the channel
may be within
a range from about 2.5 to about 12. Alternatively, the ratio of the outer
diameter to the radius of
the curvature of the channel may be within a range from about 2.7 to about 9.
Surprisingly, it has been found out that such filament geometry provides even
further
improved cleaning performance while maintaining brush comfort in the mouth. In
addition, it has
been found out that such geometry helps even more to reduce the appearance of
filament/tuft wear
since there is even less likelihood that the filaments get caught during
brushing. Further, the
manufacturability of such filaments during a toothbrush manufacturing process
is further
improved.
Each projection of the cross-shaped cross-sectional area of the filament may
be end-
rounded thereby forming a curvature. Said curvature may have a diameter. The
diameter of the
curvature of the projection may be within a range from about 0.01 mm to about
0.04 mm, or within
a range from about 0.018 mm to about 0.026 mm.
The ratio of the diameter of the curvature of the projection to the radius of
the curvature of the
channel may be within a range from about 0.2 to about 1.5, or from about 0.3
to about 1.0, or from
about 0.5 to about 0.7. Said ratio is relatively low as compared to standard
cross-shaped filaments
according to the state of the art (cf. Fig. 3 and as further described below).
In other words, the
radius of the concave curvature of the channel is relatively large with
respect to the diameter of the
curvature of the projection, i.e. with respect to the width extension of the
projection ¨ or in other
words, the diameter of the curvature of the projection can be relatively thin
as compared to the
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radius of the concave curvature of the channel. The relatively large radius
provides the relatively
thin projections with increased stability. Thus, there is less likelihood that
the filaments/projections
get damaged or that the relatively thin projections break away during the
brush manufacturing
process, in particular when the filaments get picked. In other words, the
manufacturability of such
filaments during a toothbrush manufacturing process is further improved.
Further, surprisingly, it has been found out that such filament geometry
provides even
further improved cleaning performance while maintaining brush comfort in the
mouth. In addition,
it has been found out that such geometry further helps to reduce the
appearance of filament/tuft
wear since there is even less likelihood that the filaments get caught during
brushing.
The diameter of the curvature of the projection 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.
Surprisingly it
has been found out that such filaments may adapt to the teeth contour in an
even better manner and
penetrate into the interdental spaces more easily to remove plaque and debris
more completely.
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
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 of the concave curvature 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 channels can then capture the disrupted plaque and may
move it away from
the teeth.
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.
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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 200.
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.
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
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.
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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
5 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
10 terephtalate (PBT) with or without an abrasive such as kaolin clay or a
polyamide indicator
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
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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.
A plurality of filaments according to any of the embodiments described above
are bundled
together to form a tuft which may be 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 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-
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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. As outlined above, 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
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
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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
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
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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.
The tufts 16 as illustrated in Fig. 1 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
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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 a packing factor within a range from about 40% to about 55%, or from
about 45% to about
5 50%, or about 49%. 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
10 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 20 .
15 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 min, from about 0.19 mm to
about 0.38 mill,
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 0.025 mm to about
0.10 mm, or from
about 0.03 mm to about 0.08 mm, or from about 0.04 mm to about 0.06 mm.
The ratio of the outer diameter 28 to the radius 30 of the concave curvature
34 is within a
range from about 2.5 to about 12, or from about 2.7 to about 9.
Each projection 24 is end-rounded thereby forming a curvature with a specific
diameter 42.
Said diameter42 can also be defined as the width extension 42 extending
between two opposite
lateral edges 44. The ratio of the diameter 42 of the curvature of the
projection 24 to the radius 30
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of the curvature 34 of the channel 26 is within a range from about 0.2 to
about 1.5, or from about
0.3 to about 1.0, or from about 0.5 to about 0.7.
Further, the diameter 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
diameter 42 may
be within a range from about 0.01 mm to about 0.04 mm, or within a range from
about 0.018 mm
to about 0.026 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:
Outer diameter 56: 0.295 mm
Radius 58 of the concave curvature of the channel: 0.01 mm
Ratio outer diameter 56 to radius 58 of the concave curvature: 29.5
Tapering of the projections a: 15
Diameter 62 of the curvature of the projection: 0.04 mm
Ratio of the diameter 62 to the radius 58: 4
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 cc 10
Diameter 42 of the curvature of the projection 42: 0.04 mm
Ratio of the diameter 42 to the radius 30: 0.67
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 EO_INDI EU 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 I y 20/0 2010
number of moves 3 3
Movement horizontal
used handle / mould Not 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 of the channel: 0.05 mm
Ratio of outer diameter to radius of the concave curvature: 5.38
Tapering of the projections a: 14
Diameter of the curvature of the projection: 0.029 mm
Ratio of the diameter of the curvature of the projection to the radius concave
curvature of
the channel: 0.58
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 100nmi/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 a tuft according to the present disclosure.
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."
