Note: Descriptions are shown in the official language in which they were submitted.
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COSMETIC BRUSH COMPRISING BRISTLES HAVING EXTERNAL
DEPRESSIONS
FIELD OF THE INVENTION
The present invention relates to a cosmetic brush, and more specifically, to a
brush comprising bristles having external depressions.
BACKGROUND OF THE INVENTION
Plastic brushes are known in the art. Several international applications
describe
brushes made by the injection molding process and the processes therefore.
Examples
io include: WO 02/03831 Al, titled Method and Device For Producing Bristle
Products and
Bristle Products; assigned to Coronet-Werke GmbH of Germany, German patent
application DE 10201635.6, titled Method and Device For the Production of
Bristles,
assigned to Coronet-Werke GmbH of Germany; German patent application DE
10212701.8, titled Bristle, Method and Device For Its Production and Bristle
Product,
assigned to Coronet-Werke GmbH of Germany; and German patent application
10221869.2, titled Method of Manufacturing a Bristle Structure on a Carrier,
assigned to
Coronet-Werke GmbH of Germany, the disclosures of all of which are
incorporated
herein by reference.
Generally, plastic brushes can be made by a two-step process. First, a hollow
core
having a multiplicity of orifices through its surface can be formed from a
first plastic
material. Second, a second plastic material can be injected, under pressure,
into the
hollow core, so that the escaping (or "extruded") through the recesses soft
plastic forms
individual bristles as the second material solidifies. The first and second
materials can be
identical, or different. The position of the orifices and their shapes can be
chosen to
define the position of the bristles and their cross-sectional configuration.
Now, it has been discovered that cosmetic brushes, such, for example, as those
used for mascara application to eye lashes, can be improved by providing, at
least
partially, individual bristles that have a concave portion thereon. It is
believed that such a
brush will deliver a more refined application of liquid mascara to the lashes
a nd reduce
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the potential for the lashes to "stick" to one another when the liquid mascara
is applied to
the lashes.
Accordingly, the present invention provides a cosmetic brush comprising a
plurality of bristles, wherein selected bristles have at least one external
depression
oriented in a direction parallel to the longitudinal axis of the selected
bristle, and the
process for making such a brush.
SUMMARY OF THE INVENTION
A cosmetic brush of the present invention comprises a substantially
longitudinal
stem and a plurality of bristles extending therefrom. Each bristle has a base
associated
io with the stem and a free end opposite to the base. Each bristle has
external walls and a
longitudinal axis oriented along the length of the bristle. The walls of the
bristle can be
concave, round, planar, or convex. The brush as a whole has a major axis
disposed along
the stem of the brush.
According to the present invention, at least some of the bristles, termed
herein as
"selected bristles," have at least one external depression in their walls. The
depression of
each of the selected bristles is oriented in a direction substantially
parallel to the
longitudinal axis of the bristle.
The selected bristle can have any suitable shape in its cross-section
perpendicular
to the bristle's longitudinal axis. For example, the selected bristle can have
a cross-
section that includes oblong, polygon, circular, curbed, rhombic, trapezoid,
or any other
shape.
The number of the depressions per bristle can also vary. For example, the
bristle
can have on, two, three, four, and more depressions. In one embodiment, the
depression
or depressions extend through the entire length of the selected bristle. In
ainother
embodiment, the depression or depressions extend only through a portion of the
selected
bristle. In still another embodiment, the depression is located at the free
end of the
selected bristle.
In the selected bristles having more than one depression, the location of the
depressions may vary. For example, in the selected bristles having two
depressions, the
depressions can be located opposite to each other. In the selected bristle
having three or
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four depressions, the depressions can be spaced substantially equidistantly
from one
another, as viewed in the cross-section perpendicular to the longitudinal axis
of the
selected bristle.
The bristles may have differential lengths. In one embodiment, for example,
the
lengths of the bristles are such that the ends of several bristles
consecutively disposed
next to one another, as viewed in a cross-section of the brush perpendicular
to the major
axis, form an imaginary line that is straight. In another embodiment, such a
line can be
concave or convex.
The bristles may be made to gradually taper from the base towards the free
end.
Alternatively, the bristles may have a generally uniform thickness (with the
exception of
the selected bristles cross-sections of which are at least partially affected
by the
longitudinal depression), or taper from the free ends towards the bases of the
bristles.
In one embodiment, the ends of at least some of the bristles, either selected
or
otherwise, have concave depression. Those depressions are different and
distinct from
the depressions in the walls of the bristles, for the depressions in the free
ends of the
bristles are not disposed longitudinally in relation to the longitudinal axes
of the bristles.
The longitudinal axes of the bristles and the major axis of the brush can be
mutually perpendicular. The embodiment is contemplated in which those are not
mutually perpendicular, i.e., the axes of at least some of the bristles and
the major axis of
the brush form an obtuse angle or angles therebetween.
The brush of the present invention can be made by a process that includes a so
called "injection molding" technique, i.e., a process wherein a molten
material is injected,
under pressure, into a closed form having a cavity of a desired shape, to fill
the cavity,
cooled to solidify in the cavity, and released from the cavity. Several
patents documents
listed herein above and incorporated by reference describe the injection
molding process
in sufficient detail.
More specifically, the process for making the cosmetic brush of the present
invention comprises the steps of forming a hollow stem from a first moldable
material;
providing a plurality of bristle-forming channels surrounding and abutting the
hollow
stem, each of the bristle-forming channels tenninating with an end and having
a length,
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the plurality of bristle-forming channels comprising selected bristle-forming
channels,
each of the selected bristle-forming channels having at least one protuberance
therein;
injecting a second moldable material into the hollow stem under pressure
sufficient to
rapture the hollow stem in predetermined locations corresponding to the
bristle-forming
channels and to fill the bristle-forming channels with the second moldable
material so that
the second moldable material assumes the shape of the bristle-forming
channels; and
solidifying the second moldable material disposed in the bristle-forming
channels thereby
forming the plurality of bristles of the brush being made, wherein the
plurality of bristles
comprises selected bristles formed in the selected channels and having at
least one
io external depression thereon.
The protuberances can be disposed along the length of the selected bristle-
forming
channels and / or at the end of the selected bristle-forming channels,
depending on a
desired configuration of the bristles being formed. The bristle-forming
channel can be
formed, for example, by a plurality of plates disposed consecutively adjacent
to one
another, wherein mutually adjacent plates have surface patterns that form, in
combination,
a desired profile of the bristle-forming channel.
The step of forming a hollow stem from a first moldable material can be
accomplished by injecting the first moldable material under pressure into a
support form
structured to form the hollow stem. The first moldable material and the second
moldable
material may be identical or, alternatively, may differ from one another.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side view of an embodiment of a brush according to the invention;
Fig. 2 is a cross-sectional view of the brush of Fig. 1, taken along lines 2-
2; and
Figs. 3 to 6 are perspective views of various embodiments of the selected
bristles of the
brush of the present invention.
Fig. 7 is a plan view of an exemplary einbodiment of the bristle having a
depression intermediate the base of the bristle and the end thereof.
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Fig. 8 is a schematic cross-sectional view of an embodiment of a support form
that
can be used for making the brush of the present invention by extrusion
molding.
Fig. 9 is a schematic cross-sectional and partial view of the form shown in
Fig. 8,
5 taken along lines 9-9, and showing a cross-section of a selected bristle-
forming channel having a protuberance therein.
Fig. 10 is a schematic cross-sectional view taken along lines 10-10 of Fig. 9,
and
showing a plan view of one embodiment of the protuberance of the bristle-
forming channel.
Fig. 11 is a schematic perspective view of one embodiment of the bristle-
forming
channels.
DETAILED DESCRIPTION OF THE INVENTION
Fig_ 1 shows an embodiment of a brush 10 of the present invention comprising a
substantially longitudinal core, or stem, 260 having a longitudinal, or major,
axis A, and a
plurality of bristles 50 extending therefrom. Each bristle has a base
associated with the
stem and a free end opposite to the base. Each bristle has external walls and
a
longitudinal axis B oriented along the length of the bristle (Fig. 5). The
walls of the
bristle 50 can be concave, round, planar, or convex, Figs. 3-5.
The embodiment of Fig. 1 also has an optional stem 20 that, via an optional
locking groove 30, can be attached to a handle (not shown). The brush 10 may
be
trimmed, to change the length of some bristles or otlierwise form a particular
configuration of the brush 10 in a cross-section perpendicular to the major
axis A. For
example, Figs. 2 shows that the trimming can be made to comprise an envelope
curve 60
of approxiinately triangular shape with rounded or skewed corners 70 so that
the bristles
50 have differential lengths. The same effect can be achieved by using a
process of the
present invention, and without trimming, as will be discussed in more detail
below.
According to the present invention, at least some of the bristles 50 have at
least
one external depression 120 in their walls. These bristles are termed herein
as "selected
bristles," because the process of the present invention (described herein
below) allows
one to design what bristles should be structured to have at least one external
depression.
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The depressions of the selected bristles can be oriented in a direction
parallel to the
longitudinal axes B of the bristles, or, alternatively or additionally, can be
disposed at free
ends of the bristles.
Bristles 50 can comprise bristles having a generally round cross-section
(Figs. 4
and 6), bristles 50b having a generally oblong, or elongated, cross-section
(Figs. 3 and 5),
or bristles having any otlier suitable general cross-section, for example,
polygonal. As
used herein, the term "oblong" refers to a geometrical shape that generally
has unequal
dimensions in two mutually perpendicular directions. The selected bristle can
have any
suitable shape in its cross-section perpendicular to the bristle's
longitudinal axis. For
example, the selected bristle can have a cross-section that includes oblong,
polygon,
circular, trapezoid, or any other shape.
The number of the depressions 120 per the selected bristle can vary. For
example,
the selected bristle can have one, two, three, four, and more depressions 120.
In the
selected bristles having more than one depression 120, the location of the
depressions
may vary. For example, in the selected bristles having two depressions 120,
the
depressions can be located opposite to each other, Figs. 3 and 5. In the
selected bristle
having three, four, or more depressions 120, the depressions can be spaced
substantially
equidistantly from one another, as viewed in the cross-section perpendicular
to the
longitudinal axis B of the selected bristle (Figs. 3-5) or can be
differentially spaced from
one another (not shown). In the embodiments shown in Figs. 3-5, the
depressions 120
extend through the entire length of the selected bristle. In other
embodiments, the
depression or depressions 120 can extend only tlirough a portion of the
selected bristle, as
shown, for example, in Fig. 7. The depression can extend from the base of the
selected
bristle and terminate before it reaches the free end of the selected bristle;
or the
depression can extend from the free end of the selected bristle and terminate
before it
reaches the base of the selected bristle. The embodiment is contemplated in
which the
selected bristle has more than one depression wherein at least one depression
extends
through the entire length of the bristle, and the other depression or
depressions extends
only through a portion of the length of the bristle in any manner described
herein above.
The bristles 50 may have differential lengths. In one embodiment, for example,
the lengths of the bristles 50 are such that the ends of several bristles
consecutively
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disposed next to one another, as viewed in a cross-section of the brush
perpendicular to
the major axis A, form an imaginary line that is straight (Fig. 3, line 60)_
In another
embodiment, such a line can be concave (not shown) or convex (Fig. 3, line
70). Thus, in
its cross-section perpendicular to the major axis A, the brush may or may not
be
circumferentially symmetrical.
The bristles 50 can be made to gradually taper from the base towards the free
end
(Figs. 1-6). Alternatively, the bristles 50 may have a generally uniform
thickness (with
the exception of the selected bristles, cross-sections of which are at least
partially affected
by the longitudinal depression), or taper from the free ends towards the bases
of the
bristles 50 (not shown).
In one embodiment, the ends of at least some of the bristles 50 have concave
depression 110, Fig. 4. Those concave depressions 110 are different and
distinct from the
depressions 120 in the walls of the bristles, for the depressions 110 in the
free ends of the
bristles 50 are not disposed longitudinally in relation to the longitudinal
axes B of the
bristles 50. In some embodiments of the brush of the present invention, the
selected
bristles can have both the longitudinal depression or depressions 120 and the
concave
depression 110 at the free end of the selected bristle.
The longitudinal axes B of the bristles 50 and the major axis A of the brush
10 can
be mutually perpendicular. The einbodiment is contemplated, however, in which
those
are not mutually perpendicular, i. e., the axes B of at least some of the
bristles 50 and the
major axis A of the brush 10 fonn acute or obtuse angle or angles therebetween
(not
shown).
The brush of the present invention can be made by using a technique known as
"injection molding." Injection molding is, in essence, a process wherein
molten plastic is
deposited under pressure, or injected, into a closed form having a cavity of a
desired
shape, to fill the cavity, then cooled to solidify in the cavity, and then
released from the
cavity. One skilled in the art will appreciate that using the injection
molding process, it is
possible to form virtually any desired configuration of the bristles,
includir.rg the selected
bristles of the present invention. In addition, the injection molding
technique allows one
to control the length of individual bristles, so that trimming of the finished
brush may not
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be needed in order to form a certain cross-sectional profile of the brush, as
shown, for
example, in Fig. 2.
The brush of the present invention can be made by an injection-molding
process,
for example, using a multi-component molding injection machine 200,
schematically
shown in Fig. 8. First, a hollow stem 260 is provided. The hollow stem 260 can
be made
from any suitable material, for example, plastic or resin such as
polypropylene, and may
include any suitable thermoplastic or thermosetting materials. The hollow stem
260 can
be formed by injection-molding or any other means kriown in the art. As an
example, in
Fig. 8, the hollow stem 260 is formed and disposed in the injection machine
200. The
io hollow stem 260 may comprise any suitable shape in its cross-section
perpendicular to the
major axis, for example, cylindrical (shown in the exemplary embodiment of
Fig. 1),
rectangular, triangular, polygonal, or any combination thereof, or any other
shape,
including irregular geometric shape (not shown).
A plurality of bristle-forming channels 250 is provided. The bristle-forming
channels 250 are disposed so that their entrances abut the hollow stem 260 in
predetermined locations in which the bristles 50 of the brush being
constructed should be
disposed after the brush has been constructed. The overall configuration and
geometry of
the bristle-forming channels 250 corresponds to the desired overall geometry
and
configuration of the brush being made. Each of the bristle-forming channels
250
terminates with an end and has a predetermined length. Depending on the size
and length
of the bristle-forming channels 250, the bristle-formirng channels 250 can be
made by any
means known in the art, for example using conventional drilling techniques,
laser,
chemical erosion, wire electrical discharge machine (EDM), or any other
suitable means.
The bristle-forming channels 250 can be formed, for example, by a plurality of
coated
plates 300 (Fig. 11) disposed consecutively adjacent to one another, wherein
mutually
adjacent plates 300 have surface patterns that form, in combination, a desired
profile of
the bristle-forming channels 250.
In accordance with the present invention, the plurality of bristle-forming
channels
250 include selected bristle-forming channels 250a, i. e., the channels that
are structured to
form the selected bristles having at least one ex=ternal depression 120
thereon, as
described herein above. For this purpose, each of the selected bristle-forming
channels
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250a has at least one protuberance 290 therein. The protuberance or
protuberances 290
can be disposed along the length of the selected bristle-forming channel 250a,
at the end
of the selected bristle-forming channels 250a, or both, depending on a desired
configuration of the selected bristle being formed.
In the next step, a second moldable material 270 is injected, under pressure,
into
the hollow stem, to form the bristles (Fig. 8). The second moldable material
can comprise
the material identical to the first moldable material, or, alternatively, may
differ
therefrom. Only for the purposes for example, the second moldable material can
comprise any suitable thermoplastic elastomer (TPE), such as, for example,
styrene-
ethylene-butylene-styrene (SEBS) block copolymer. The pressure under which the
second moldable material 270 is injected should be sufficient to rapture the
hollow stem
260 and form perforations in locations corresponding to the bristle-forming
channels 250
and further to fully fill the bristle-forming channels 250 with the second
moldable
material 270 so that the second moldable material 270 assumes the shape of the
bristle-
forming channels 250. These perforations formed in the stem 260 serve, in
effect, as
spiimerets for the second moldable material. The second moldable material 270
that fills,
under pressure, the selected bristle-forming channels 250 forms the selected
bristles that
have external depressions described herein above, the depressions being a
"negative" of
the protuberances 290 of the selected bristle-forming channels 250a.
After the second moldable material 270 solidify in the bristle-forming
channels
250, the brush comprising the stem 260 and the plurality oof bristles 50
extending
therefrom can be released from the injection machine. If the plurality of
plates 300 is
used to form the bristle-forming chamlels 250, the plates 300 can be moved
apart from
one another, thereby releasing the formed bristles 50.
If desired, an optional step of injecting a third moldable rnaterial 280 (Fig.
8) into
the hollow stem 260 to fill the stem 260, can be used. When the process is
completed, the
bristles 50 are integrally bound to the third material 280 that has filled the
stem 260. The
third moldable material can comprise a material identical to at least one of
the first
moldable material or the second moldable material, or can be chose to be
different from
either the first moldable material and the second moldable material.
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All documents cited in the Detailed Description of the Invention are, in
relevant
part, incorporated herein by reference; the citation of any document is not to
be construed
as an admission that it is prior art with respect to the present invention.
While particular embodiments of the present invention have been illustrated
and
5 described, it would be obvious to those skilled in the art that various
other changes and
modifications can be made without departing from the spirit and scope of the
invention.
It is, therefore, intended to cover in the appended claims all such changes
and
modifications that are within the scope of this invention.
