Note: Descriptions are shown in the official language in which they were submitted.
CA 02722569 2010-10-25
WO 2009/137259
PCT/US2009/040889
COSMETIC APPLICATOR ASSEMBLY
FIELD OF THE INVENTION
The present invention relates to applicators for applying cosmetics to human
hairs or
eyelashes, and specifically to a cosmetic applicator assembly that includes a
bi-injection
molded polymeric brush complementarily engaged with a twisted wire brush. More
specifically, the bi-injection molded polymeric brush of the present invention
comprises an
elongated polymeric core formed of a first, relatively stiffer polymeric
material and multiple
protruding polymeric tines formed of a second, relatively softer polymeric
material.
BACKGROUND OF THE INVENTION
A cosmetic brush is typically used for applying cosmetic (e.g., mascara and
the like) to
an application area, e.g., a user's hairs or eyelashes. Such a cosmetic brush
can also be used
for separating hairs or eyelashes and removing excess cosmetic therefrom.
One common type of cosmetic brush includes a twisted wire brush formed by
first
folding a single metallic wire into a generally U-shaped configuration to
provide a pair of
parallel wire segments, then disposing multiple relatively soft bristles (also
referred to as
filaments or fibers, which are typically formed of nylon strands) between a
portion of a length
of the wire segments, which holds or clamps the soft bristles securely at
their midpoints,
followed by twisting or rotating the wire segments about each other, thereby
forming a helical
core (also known as a twisted wire core) with soft bristles radially extending
therefrom in a
helical or spiral manner. The radially extending soft bristles jointly form a
bristle portion or a
bristle head of the twisted wire brush, which can be used for applying a
coating of mascara or
other cosmetic onto hairs or eyelashes of a user. The soft and flexible
bristles of the twisted
wire brush are particularly effective in providing a good grip over the fine
hairs or eyelashes
and allowing the mascara to thoroughly coat over the hairs or eyelashes.
However, the mascara-coated hairs or eyelashes have a tendency to stick to one
another and form unaesthetic clumps. The above-described twisted wire brushes
with soft
bristles, although effective in applying mascara onto the hairs or eyelashes,
cannot sufficiently
separate the clumped hairs or eyelashes from one another. In order to
eliminate or reduce the
clumping, a post-application doctoring or arrangement step can be carried out
to separate the
clumped hairs or eyelashes, by using a separate twisted wire brush with
relatively stiff bristles
or more preferably, a separate comb with stiff teeth.
1
CA 02722569 2010-10-25
WO 2009/137259
PCT/US2009/040889
To avoid the inconvenience of having to conduct each of the application and
doctoring/arrangement steps using separate tools, it is desirable to integrate
a twisted wire
brush of soft bristles with a comb of stiff teeth to form a single cosmetic
applicator. Various
prior art references have disclosed such integrated cosmetic applicators with
different
arrangements and constructions of the twisted wire brush and the comb. For
example, U.S.
Patent No. 3,921,650 discloses a cosmetic applicator having a handle and a
rod, while one end
of the rod contains a comb with relatively stiff teeth extending
perpendicularly from one side
of a base portion, a twisted wire brush with relatively soft bristles
extending perpendicularly
from the other side of the base portion, and a serrated portion at the tip of
the rob. U.S. Patent
No. 6,408,857 discloses a cosmetic applicator including a twisted wire brush
with relatively
soft bristles that is bent into a closed loop, and into this loop is inserted
a comb with relatively
stiff teeth extending from either one side or both sides. The teeth of the
comb are offset from
the bristles of the twisted wire brush, so that the cosmetic application has a
cross-section that
resembles either a "T" (if the comb only has teeth extending from one side) or
a "+" (if the
comb has teeth extending from both sides). U.S. Patent Application Publication
No.
2004/0221865 discloses a mascara brush containing both an application brush
part and an
arrangement brush part. The arrangement brush part includes a comb with
relative stiff teeth
formed by injection molding, while the application brush part includes a
twisted wire brush
with relatively soft bristles. The arrangement brush part and the application
brush part are
affixed to each other so that the teeth of the comb are offset from the
bristles of the twisted
wire brush, thereby forming a brush head with both stiff teeth and soft
bristles.
Combs in the above-described prior art integrated cosmetic applicators are
typically
formed by a single injection molding process, in which a hot molten polymer is
first injected
into a mold and then cooled down to form a molded article. Correspondingly,
both the teeth
of the comb and the core of the comb are formed by the same polymer. Because
the core of
the comb provides structural support for the entire comb, the polymer that
forms such core has
to be hard enough to provide the required structural support. However, the
teeth of the comb,
when formed of the same hard polymer, may be too stiff or rigid that they lose
grip on the
hairs or eyelashes and are not able to get between the clumped hairs or
eyelashes.
Correspondingly, combs of the prior art integrated cosmetic applicators
described hereinabove
may not be effective in separating the clumped hairs or eyelashes.
There is therefore a continuing need for improved cosmetic applicators of dual
functions, i.e., which can be used for performing both the cosmetic
application function and
2
CA 02722569 2010-10-25
WO 2009/137259
PCT/US2009/040889
the hair/eyelash arrangement function, but without the above-described
drawbacks of the prior
art applicators.
SUMMARY OF THE INVENTION
In one aspect, the present invention relates to an integrated cosmetic
applicator
assembly containing a polymeric brush and a twisted wire brush. The polymeric
brush has an
elongated polymeric core and multiple polymeric tines protruding from the
elongated
polymeric core. More specifically, the elongated polymeric core comprises a
first polymeric
material of a first tensile modulus, while at least some of the polymeric
tines comprise a
second polymeric material of a second tensile modulus that is smaller than the
first tensile
modulus. The twisted wire brush comprises a metal wire core and multiple
bristles protruding
from the metal wire core. The elongated polymeric core of the polymeric brush
is adapted for
complementarily engaging at least a portion of the metal wire core of the
twisted wire brush to
form the integrated cosmetic applicator assembly.
The integrated cosmetic applicator assembly of the present invention can be
used to
effectively perform both the application function and the
doctoring/arrangement function. The
twisted wire brush with relatively soft bristles is useful for applying a
liquid or semi-liquid
cosmetic product (e.g., mascara) to human hairs or eyelashes, while the
polymeric brush with
relatively stiff tines (in comparison with the bristles of the twisted wire
brush) is useful for
subsequent separation and arrangement of such hairs or eyelashes.
Alternatively, the
polymeric brush may comprise relatively soft tines useful for applying the
cosmetic product to
human hairs or eyelashes, while the twisted wire brush may comprise relative
stiff bristles
useful for subsequent separation and arrangement of the hairs or eyelashes.
More importantly,
by forming at least some of the protruding tines of the polymeric brush with a
polymeric
material (i.e., the second polymeric material) relatively softer than the
polymeric material used
for forming the core of the polymeric brush (i.e., the first polymeric
material), the polymeric
brush achieves a much better grip on the hairs or eyelashes, while the core of
the polymeric
brush can continue to provide the required structural support so that the
polymeric brush of the
present invention can still retain its overall shape during the
doctoring/arrangement step,
without significant bending or distortion.
Note that the term "complementarily engaging" or "complementarily engaged" as
used
herein refers to formation of an interlocking relationship between two or more
complementary
elements or structures. Further, the term "polymer" or "polymeric" as used
herein refers to
3
CA 02722569 2010-10-25
WO 2009/137259
PCT/US2009/040889
any material, composition, structure, or article that comprises one or more
polymers, which
can be homopolymers, copolymers, or polymer blends.
In another aspect, the present invention relates to a polymeric cosmetic brush
for use in
combination with a twisted wire cosmetic brush. Such polymeric cosmetic brush
contains an
elongated polymeric core having a longitudinal axis and multiple polymeric
tines protruding
from the elongated polymeric core. The elongated polymeric core comprises a
first polymeric
material of a first tensile modulus, while at least some of the polymeric
tines comprise a
second polymeric material of a second tensile modulus that is less than the
first tensile
modulus. The elongated polymeric core further comprises one or more
protrusions and/or
recesses adapted for complementarily engaging one or more corresponding
portions of a
twisted wire brush.
In still another aspect, the present invention relates to simply a polymeric
cosmetic
brush comprising an elongated polymeric core having a longitudinal axis and
multiple
polymeric tines protruding from the elongated polymeric core, such elongated
polymeric core
comprising a first polymeric material of a first tensile modulus, while at
least some of the
polymeric tines comprising a second polymeric material of a second tensile
modulus that is
less than the first tensile modulus.
In a further aspect, the present invention relates to a method of making a
cosmetic
applicator assembly, comprising:
forming a polymeric brush comprising an elongated polymeric core and multiple
polymeric tines protruding from the elongated polymeric core, wherein the
elongated
polymeric core comprises a first polymeric material of a first tensile
modulus, wherein at least
some of the polymeric tines comprise a second polymeric material of a second
tensile modulus
that is less than the first tensile modulus, wherein the elongated polymeric
core further
comprises one or more protrusions and/or recesses adapted for complementarily
engaging one
or more corresponding portions of a twisted wire brush;
forming a twisted wire brush comprising a metal wire core and multiple
bristles
protruding from the metal wire core; and
complementarily engaging the elongated polymeric core of the polymeric brush
with
one or more portions of the twisted wire brush to form the cosmetic applicator
assembly.
Preferably, but not necessarily, the polymeric brush as described hereinabove
is formed
by a bi-injection molding process, in which two or more different polymeric
materials are
simultaneously injection molded to form one article.
4
CA 02722569 2010-10-25
WO 2009/137259
PCT/US2009/040889
Other aspects and features of the present invention will become more apparent
from
the following detailed description with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. lA is a perspective view of an exemplary polymeric brush, according to
one
embodiment of the present invention.
FIG. 1B is a top view of the exemplary polymeric brush of FIG. 1A.
FIG. 1C is a representative or schematic cross-sectional view of the exemplary
polymeric brush of FIGS. lA and 1B, along the line A-A in FIG. 1B.
FIG. 2A is a side view of an exemplary twisted wire brush, according to one
embodiment of the present invention.
FIG. 2B is a representative or schematic cross-sectional view of the exemplary
twisted
wire brush of FIG. 2A, along the line B-B.
FIG. 3A is a side view of a cosmetic applicator assembly formed by
complementarily
engaging the polymeric brush of FIGS. 1A-1C with the twisted wire brush of
FIGS. 2A-2B,
according to one embodiment of the present invention.
FIG. 3B is a perspective view of the cosmetic applicator assembly of FIG. 3A.
FIG. 3C is a representative or schematic cross-sectional view of the cosmetic
applicator assembly of FIGS. 3A-3B, alone the line C-C in FIG. 3A.
FIG. 4 is a side view of a cosmetic package comprising the cosmetic applicator
assembly of FIGS. 3A-3C as mounted on one end of a rod, while a cap is mounted
at the other
end of the rod and adapted for complementarily engaging a neck portion of a
cosmetic
container, according to one embodiment of the present invention.
FIGS. 5-6 are perspective views of exemplary polymeric brushes with polymeric
tines
of alternative shapes, according to alternative embodiments of the present
invention.
5
CA 02722569 2010-10-25
WO 2009/137259
PCT/US2009/040889
FIG. 7A is a perspective view of an exemplary polymeric brush having curved
polymeric tines, according to one embodiment of the present invention.
FIG. 7B illustrates the relative positions of two representative tines of the
exemplary
polymeric brush of FIG. 7A, as located adjacent to each other in the same row.
DETAILED DESCRIPTION OF THE INVENTION, AND PREFERRED EMBODIMENTS
THEREOF
In the following description, numerous specific details are set forth, such as
particular
structures, components, materials, and dimensions, in order to provide a
thorough
understanding of the present invention. However, it will be appreciated by one
of ordinary
skill in the art that the invention may be practiced without these specific
details. In other
instances, well-known structures, components, materials, or dimensions may be
described in
less detail here in order to avoid obscuring elements of the present
invention.
As mentioned hereinabove, the present invention provides an integrated
cosmetic
applicator assembly containing both a twisted wire brush and a bi-injection
molded polymeric
brush. Specifically, the bi-injection molded polymeric brush of the present
invention contains
an elongated polymeric core formed of a first, relatively stiff polymeric
material and multiple
protruding polymeric tines formed of a second, relatively soft polymeric
material. The softer
tines of such a bi-injection molded polymeric brush are believed to provide a
much better grip
on the hairs or eyelashes and is therefore more effective in separating
clumped hairs or
eyelashes, while the stiff core of such a bi-injection molded polymeric brush
can continue to
provide the required structural support, so that the polymeric brush of the
present invention
can still retain its overall shape during the doctoring/arrangement step,
without significant
bending or distortion.
FIGS. 1A-1C shows various views of a bi-injection molded polymeric brush 1,
according to one exemplary embodiment of the present invention. The bi-
injection molded
polymeric brush 1 includes a handle portion 10 and a brush head portion 20.
The brush head
portion 20 has an elongated polymeric core 24 and multiple polymeric tines 26,
which
protrude perpendicularly from the elongated polymeric core 24.
Specifically, the elongated polymeric core 24 is formed of a first, relatively
stiff
polymeric material, while at least some (and preferably all) of the multiple
polymeric tines 26
are formed of a second, relatively soft polymeric material. The first,
relatively stiff polymeric
material can be characterized by a first tensile modulus preferably ranging
from about 800
6
CA 02722569 2010-10-25
WO 2009/137259
PCT/US2009/040889
MPa to about 3000 MPa, while the second, relatively soft polymeric material
can be
characterized by a second tensile modulus that is less than the first tensile
modulus, which
preferably ranges from about 35 MPa to about 1200 MPa. More preferably, the
first tensile
modulus ranges from about 1000 MPa to about 2000 MPa, and the second tensile
modulus
ranges from about 95 MPa to about 570 MPa. Most preferably, the first tensile
modulus
ranges from about 1250 MPa to about 1600 MPa, and the second tensile modulus
ranges from
about 200 MPa to about 280 MPa. Exemplary polymers that can be used as the
first polymeric
material in the present invention include, but are not limited to: ethylene-
propylene diene
monomer or EDPM rubber, ethylene vinyl acetate copolymer, acrylonitrile
polymers,
polyamide, polycarbonate, polyester, polyethylene terephthalate, polymethyl
methacrylate,
polyolefins (such as, for example, polyethylene and polypropylene),
polyoxymethylene,
polystyrene, polyurethane, and acrylonitrile butadiene styrene. Exemplary
polymers that can
be used as the second polymeric material in the present invention include, but
are not limited
to: silicone elastomers, thermoplastic elastomers (such as, for example,
styrene-ethylene-
butylene-styrene or SEBS block copolymer), vinyl elastomers (such as ethyl
vinyl acetate or
EVA), thermoplastic polyester elastomers (such as those commercialized under
the trademark
Hytrel by Du Pontde Nemours), thermoplastic polyurethane elastomers (such as
those
commercialized under the trademark Pellethane by Dow Chemical Company),
acrylonitrile
polymers, and ethylene propylene diene monomer or EDPM rubber. It is important
to note
that the list of polymeric materials provided hereinabove are only for
illustration purposes, and
any other suitable polymeric material known in the art can be used in place of
or in
combination with the above-listed materials.
In a preferred embodiment of the present invention, the first polymeric
material is
polypropylene, and the second polymeric material is a silicone elastomer or a
thermoplastic
polyester elastomer. In an alternative embodiment, the first polymeric
material is
polycarbonate or acrylonitrile butadiene styrene, and the second polymeric
material is a
thermoplastic polyurethane elastomer. In a further alternative embodiment, the
first polymeric
material is polyoxymethylene, and the second polymeric material is a
thermoplastic polyester
elastomer.
The elongated polymeric core 24 of the polymeric brush 1 may comprise one or
more
protrusions and/or recesses for complementarily engaging one or more
corresponding portions
of a metal wire core of a twisted wire brush. On one hand, the term
"protrusion" as used
herein broadly covers any protruding structure, which includes, but is not
limited to: clips,
hooks, spikes, nodes, lugs, pins, and tabs. On the other hand, the term
"recess" as used herein
7
CA 02722569 2013-03-18
broadly covers any recessing structure, which includes, but is not limited to:
surface openings
(such as grooves, pits or holes), loops, bores, central lumens, and
clearances. For example, the
elongated polymeric core 24 may comprise a surface groove that extends along
the
longitudinal axis of the polymeric core 24, and at least one portion of the
metal wire core of
the twisted wire brush can be inserted into such surface groove, as described
by U.S. Patent
No. 3,921, 650.
The elongated polymeric core 24 may comprise an annular surface groove, and at
least one portion of the metal wire core of the twisted wire brush forms a
loop that is adapted
to engage such annular surface groove of the elongated polymeric core 24, as
described by
U.S. Patent No. 6,408,857
Preferably, but not necessarily, the elongated polymeric core 24 contains a
central lumen 22 with at least one opening at one side of the elongated
polymeric core 24, as
illustrated in FIGS. 1A-1C. Such a central lumen 22 may extend through the
entire length of
the elongated polymeric core 24, or it may extend only through a portion
thereof and close at a
distal end 24T of the polymeric core 24, as shown in FIGS. 1A-1B. The opening
in the central
lumen 22 is preferably characterized by an angel a (shown in FIG. 1C), which
ranges from
about 1 to about 90 , more preferably from about 15 to about 75 , and most
preferably from
about 30 to about 60 .
The handle portion 10 of the exemplary polymeric brush 1 includes a central
lumen 12
that connects with the central lumen 22 of the elongated polymeric core 24.
Further, the
central lumen 12 has a narrow aperture or slit 14 that also connects with the
opening of the
central lumen 22 of the elongated polymeric core 24. The central lumens 12 and
22 in the
polymeric brush 1 are adapted for accommodating the metal wire core of a
twisted wire brush,
with which the polymeric brush 1 is to be complementarily engaged. The slit 14
at the handle
portion 10 allows the soft bristles of the twisted wire brush to pass through
the handle portion
10 with little or no bending, and the opening of the central lumen 22 in the
elongated
polymeric core 24 accommodates the soft bristles of the twisted wire brush and
allow them to
fully extend outward from the elongated polymeric core 24.
FIG. 2A shows the side view of an exemplary twisted wire brush 2, with which
the
polymeric brush 1 of FIGS. IA-IC is to be complementarily engaged.
Specifically, the
twisted wire brush 2 includes a metal wire core 30, which is formed by folding
a single
metallic wire into a U-shape to provide a pair of parallel wire segments, and
then twisting or
rotating the pair of wire segments about each other in a helical manner. The
twisted wire
brush 2 also includes multiple soft and flexible bristles 42 and 44 of
different lengths, which
8
CA 02722569 2010-10-25
WO 2009/137259
PCT/US2009/040889
extend radially from the metal wire core 30. Specifically, the longer bristles
42 are arranged
at one side of the metal wire core 30, while the shorter bristles 44 are
arranged at the other side
of the metal wire core 30, as shown in the cross-sectional view of FIG. 2B.
More specifically,
when viewed at the cross-section, the longer bristles 42 jointly form a fan-
shaped
configuration around the metal wire core 30, and such configuration is
preferably
characterized by an angel that is the same as the angle a shown in FIG. 1C.
Correspondingly, the twisted wire brush 2 of FIG. 2A-2B can be complementarily
engaged with the polymeric brush 1 of FIG. 1A-1C to form a cosmetic applicator
assembly 3,
as shown in FIGS. 3A-3C. Specifically, the shorter bristles 44 and the metal
wire core 30 of
the twisted wire brush 2 can fit into the central lumen 22 of the polymeric
brush 1, while the
longer bristles 42 of the twisted wire brush 2 can fully extend outward from
the opening of the
central lumen 22 of the polymeric brush 1. The metal wire core 30 of the
twisted wire brush
22 may extend along the entire length of the polymeric brush 1 through the
central lumens 22
and 12 of the polymeric brush 1 and further outwards. The resulting cosmetic
applicator
assembly 3 therefore has the polymeric tines 26 on one side and the soft
bristles 42 on the
other side, as shown in FIG. 3C.
It is important to note that the above-described specific configurations for
complementarily engaging the elongated polymeric core of the polymeric brush
and the metal
wire core of the twisted wire brush are only described herein for illustrative
purposes. Such
specific configurations should not be construed in any manner as limiting the
broad scope of
the present invention, and any other means or arrangement that is obvious to a
person
ordinarily skilled in the art for complementarily engaging the elongated
polymeric core of the
polymeric brush and the metal wire core of the twisted wire brush is also
readily covered by
the present invention.
The polymeric tines of the polymeric brush may be formed of either the same or
different polymeric materials. In a specific embodiment of the present
invention, all of the
protruding polymeric tines of the polymeric brush comprise the second,
relatively soft
polymeric material. In an alternative embodiment of the present invention,
some of the
protruding polymeric tines of the polymeric brush comprise the second,
relatively soft
polymeric material, while other tines may comprise the first, relatively stiff
polymeric material
that is used to form the elongated polymeric core of the polymeric brush. In a
further
alternative embodiment of the present invention, some of the protruding
polymeric tines may
even comprise a third polymeric material that is different from the first and
second polymeric
materials. Such different polymeric tines of different compositions can be
arranged in any
9
CA 02722569 2013-07-08
configurations with respective to one another, either randomly or into an
orderly pattern. For
example, the polymeric tines of the same composition may be arranged into one
or more
straight rows that are substantially parallel to the longitudinal axis of the
elongated polymeric
core of the polymeric brush, or into one or more spirals that wind around the
longitudinal axis
of the elongated polymeric core. Note that the term "substantially
perpendicular" or
"substantially parallel" as used herein refers to less than 10 degrees of
deviation from a
perpendicular or parallel direction.
The polymeric brush of the present invention may have tines of any size,
shape, and
spacing suitable for its intended functions, e.g., application, arrangement,
and/or separation of
human hairs or eyelashes. Preferably, but not necessarily, the tines of the
polymeric brush of
the present invention have an average height ranging from about 0.1 mm to
about 10 mm,
more preferably from about 0.5 mm to about 7 mm, and most preferably from
about 0.8 mm to
about 5 mm. The average cross-sectional diameter of the polymeric tines
preferably ranges
from about 0.1 mm to about 2 mm, more preferably from about 0.2 mm to about
1.5 mm, and
most preferably from about 0.3 mm to about 0.9 mm. The polymeric brush
preferably has
cylinder-shape tines with tapered ends, as shown in FIGS. 1A-3C.
Alternatively, the
polymeric brush may have spike-shaped polymeric tines 26', as shown in FIG. 5.
For a further
example, the polymeric brush of the present invention may have fin-shaped
polymeric tines
26", as shown in FIG. 6. Note that the polymeric tines of the polymeric brush
can either have
the same size and/or shape, or have different sizes and/or shapes. The tines
can be spaced or
arranged in any suitable manner. For example, the tines can be arranged into
straight rows
that are substantially parallel to the longitudinal axis of the polymeric
brush (as shown in the
drawing figures described hereinabove), or zigzagged rows with center lines
substantially
parallel to the longitudinal axis of the polymeric brush, or spiral rows that
wind around the
longitudinal axis of the polymeric brush. Preferably, but not necessarily, the
polymeric tines
can be arranged substantially perpendicular to the surfaces of the elongated
polymeric core of
the polymeric brush, as shown in the above-described drawings. Alternatively,
the tines can
be tilted or slanted from the surfaces of the elongated polymeric core by any
angle ranging
from about 5 degrees to about 85 degrees. For example, tines in the same row
may calve or
bend in such a manner that top portions of adjacent tines in the same row are
curved away
from each other with respect to the center line of the row, as described by
U.S. Patent No.
6,581,610, and as illustrated in FIGS. 7A and 7B. Specifically, tines 126A and
126B in the
CA 02722569 2010-10-25
WO 2009/137259
PCT/US2009/040889
same row 124 can be curved away from each other with respect to the center
line of the row
124 (as indicated by the dotted line).
The cosmetic applicator assembly as described hereinabove may further comprise
one
or more optional components, such as, for example, a cap 54 and a rod 52 that
extends from
the cap 54, as shown in FIG. 4. The rod 52 may contain a recess or protrusion
adapted for
complementarily engaging the handle portion 10 of the polymeric brush 1 and
the metal wire
core 30 of the twisted wire brush 2. The cap 54 is adapted for complementarily
engaging a
neck portion 62 of a cosmetic container 60 that contains therein a liquid or
semi-liquid
cosmetic, such as mascara. Preferably, but not necessarily, the cap 54
contains internal
threads (not shown), and the neck portion 62 of the container 60 contains
external threads 64
that are complementary to the internal threads of the cap 54, so that the cap
54 can be screwed
onto the container 60 in a leak-tight manner. Note that other affixation means
or mechanisms,
either mechanical or adhesive-based, can be readily used for affixing or
otherwise engaging
the cap 54 with the neck portion 62 of the container 60. The neck portion 62
of the container
60 may also contain one or more internal wiper structures (not shown) for
removing excess
cosmetic from the cosmetic applicator assembly 3 when the cosmetic applicator
assembly is
being removed from the container 60.
The polymeric brush of the present invention, as described hereinabove, can be
readily
formed by a bi-injection molding process, in which two different thermoplastic
or
thermosetting polymers are injection-molded together to form a single article,
i.e., the
polymeric brush of the present invention. First, a first polymer with a
relatively high tensile
modulus can be melted and injected at high pressure into a first mold, which
preferably
contains two or more solid parts that are complementarily engaged with one
another to define
at least a first cavity therein. The first cavity may correspond to the
desired shape of the
elongated polymeric core to be formed. After a cooling period sufficient to
allow the molten
first polymer to solidify (either completely or partially), the two or more
solid parts of the first
mold are disengaged from one another to expose an elongated polymeric core
formed by the
solidified first polymer. The elongated polymeric core so formed is then
transferred into a
second mold, which also contains two or more solid parts complementarily
engaged with one
another to define cavities that not only accommodate the elongated polymeric
core already
formed, but also define the desired shapes of the polymeric tines to be
formed. A second
polymer with a relatively low tensile modulus, preferably already melted, can
be injected at
high pressure into the second mold. After the molten second polymer cools down
and
solidifies (either completely or partially), the two or more solid parts of
the second mold are
11
CA 02722569 2010-10-25
WO 2009/137259
PCT/US2009/040889
disengaged from one another, thereby exposing multiple polymeric tines that
have been
molded over the elongated polymeric core to form the polymeric brush of the
present
invention. In a particular preferred embodiment of the present invention, the
time interval
between the first and second molding step is relatively short, e.g., less than
20 minutes, more
preferably less than 10 minutes, and most preferably less than 2 minutes, so
that the surface of
the elongated polymeric core is still hot from the first molding step when the
second molding
commences. In this manner, the surface energy of the elongated polymeric core
remains
relatively high when the molten second polymer is injected into the second
mold, which
allows the second polymer to readily adhere to the surface of the elongated
polymeric core.
The polymeric tines can therefore be adhered to the surface of the elongated
polymeric core
without the need for any adhesive. Alternatively, the surface of the elongated
polymeric core
may contain any suitable patterns (e.g., recesses or grooves) for increasing
the adhesion or
attachment between the polymeric tines and the elongated polymeric core.
While the present invention has been described hereinabove with reference to
specific
embodiments, features and aspects, it will be recognized that the invention is
not thus limited,
but rather extends in utility to other modifications, variations,
applications, and embodiments,
and accordingly all such other modifications, variations, applications, and
embodiments are to
be regarded as being within the spirit and scope of the present invention.
12
