Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF MANUFACTURING TOOTHBRUSHES WITH COMMON CORE
FIELD OF THE INVENTION
[0001] The invention relates generally to manufacturing of dental care
implements, and
more particularly, to methods of manufacturing toothbrushes having common core
and
overmolds.
BACKGROUND OF THE INVENTION
[0002] Oral care implements, especially toothbrushes, are in use by many
people on a
daily basis. With such devices, a handle is usually provided to be grasped and
manipulated by the user as needed. However, many handles are simply linear or
anatomically corrected rods of relatively rigid material which are neither
comfortable, nor
given to easily manipulation. Further, use of an oral care implement may
commonly
occur under wet conditions, which can cause the handle to be slippery.
[0003] To provide improved control and greater comfort for the user,
toothbrushes are
being provided with softer elastomeric padding over parts of the toothbrush
handle, with
exemplary teachings provided in U.S. Patent Nos. 7,458,125; 7,240,390; and
7,401,377.
Examples of soft handle coverings for other oral care implements are taught in
U.S.
Patent No. 5,501,597; 6,361,317; and 7,226,289.
[0004] The problems associated with relatively rigid material handle increase
when the
toothbrush is electrical or otherwise powered, due to the vibrations caused by
the
electrically manipulated toothbrush head during use. The control of such
toothbrushes
becomes more problematic when the electric/powered toothbrush is used by the
smaller
hands of children.
[0005] Accordingly, there is a need for an oral care implement that provides
for
improved control and greater comfort for the use of the implement regardless
of the size
of the user's hand.
SUMMARY OF THE INVENTION
[0006] One aspect of the preferred embodiments includes a method of
manufacturing a
dental implement. The dental implement includes a shaft having a plastic core
and an
overmold. The method includes forming a plastic core in a first mold, removing
the
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plastic core from the first mold, selecting one of a plurality of second
molds, with each of
the plurality of second molds having a different mold cavity such that an
overmold
formed by one of the plurality of the second modes and an overmold formed by
another
one of the plurality of second molds have different configurations, placing
the plastic
core into the selected one of the plurality of second molds, forming an
overmold about
the plastic core by injecting a material into the mold cavity of the selected
one of the
plurality of second molds, and removing the plastic core and overmold from the
mold
cavity.
[0007] Another aspect of the preferred embodiments includes method of
manufacturing a
dental implement. The dental implement includes a shaft having a plastic core
and an
overmold. The method includes providing a first plastic core formed from a
first mold,
selecting a first one of a plurality of second molds, each of the plurality of
second molds
having a different mold cavity such that an overmold formed by one of the
plurality of
the second molds and an overmold formed by another one of the plurality of
second
molds have different configurations, placing the first plastic core into the
first one of the
plurality of second molds, forming a first overmold about the first plastic
core by
injecting a material into the mold cavity of the first one of the plurality of
second molds,
and removing the first plastic core and the first overmold from the mold
cavity. The
method also includes providing a second plastic core formed from the first
mold,
selecting a second one of a plurality of second molds, placing the second
plastic core into
the second one of the plurality of second molds, forming a second overmold
about the
second plastic core by injecting a material into the mold cavity of the second
one of the
plurality of second molds, and removing the second plastic core and the second
overmold
from the mold cavity.
[0008] A further aspect of the preferred embodiments includes a dental
implement kit.
The kit includes a first dental implement with a first plastic core formed of
a first mold,
and a first overmold formed of a first one of a plurality of second molds,
each of the
plurality of second molds having a different mold cavity such that an overmold
formed
by one of the plurality of the second molds and an overmold formed by another
one of
the plurality of second molds have different configurations. The kit also
includes a
second dental implement with a second plastic core formed of the first mold,
and a
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second overmold formed of a second one of a plurality of second molds. The
first
overmold and the second overmold have different configurations.
[0009] In certain embodiments, the method also includes chemically blending
the
injected material with the plastic core, and cooling the overmold with the
chemically
blended injected material and the plastic core forming a chemical bond
therebetween.
Within this exemplary aspect, the injected material preferably has a
temperature that
softens the plastic core for chemically blending the core with the injected
material. In a
further aspect of the preferred embodiments, the method also includes
arranging
electrically functional elements within the plastic core, the electrically
functional
elements including an electrically operated functional unit and an electric
supply unit
connectable to an energy source for energizing the electrically operated
functional unit.
In yet another aspect of the preferred embodiments, the dental implement
includes a head
member and a neck located between the head member and the plastic core, and
the
method may further include attaching a plurality of bristles to the head
member to form a
brush head. While not being limited to a particular material, the injected
material may be,
for example, an elastomer.
[0010] Further areas of applicability of the present invention will become
apparent from
the detailed description provided hereinafter. It should be understood that
the detailed
description and specific examples, while indicating the preferred embodiment
of the
invention, are intended for purposes of illustration only and are not intended
to limit the
scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention will become more fully understood from the
detailed
description and the accompanying drawings, wherein:
[0012] Fig. 1 is a top plan view of an exemplary embodiment of a toothbrush
constructed
in accordance with the preferred embodiments of the invention;
[0013] Fig. 2 is a second top plan view of the toothbrush shown in Fig. 1;
[0014] Fig. 3 is a side sectional view taken along line of Fig. 2;
[0015] Fig. 4 is a top plan view of another exemplary embodiment of a
toothbrush
constructed in accordance with the preferred embodiments;
[0016] Fig. 5 is a second top plan view of the toothbrush shown in Fig. 4; and
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[0017] Fig. 6 is a side sectional view taken along line VI-VI of Fig. 5.
DETAILED DESCRIPTION
[0018] The following description of the preferred embodiment(s) is merely
exemplary in
nature and is in no way intended to limit the invention, its application, or
uses.
[0019] Unless otherwise specified, all amounts, quantities, and geometric
features
expressed herein and elsewhere in the specification should be understood to
include
substantial approximations of the expressed term. For example, the term
"planar" should
be understood as including generally or approximately planar configurations.
[0020] The figures illustrate an oral care or dental implement in the form of
a toothbrush
having an improved handle and a head with bristles or other tooth engaging
elements.
While reference is made to a toothbrush with an improved handle, other oral
care
implements, such as inter-proximal picks, flossing tools, plaque scrapers,
tongue and soft
tissue cleansers/massagers, and the like, may use the same handle. It should
also be
understood that other embodiments may be utilized and that structural and
functional
modifications may be made without departing from the scope of the present
invention.
[0021] While not being limited to a particular embodiment, the exemplary
aspects of the
invention include a toothbrush with a rigid plastic core handle that is
chemically bonded
to a thermoplastic elastomer overmold during an overmolding process, with the
overmold
defining a gripping region for a user's hand during use of the toothbrush. The
resulting
overmold grip may have different exterior shapes for different types of users
(e.g., adults,
children, boys, girls, men, women) with the different shapes altered to
anatomically fit
the targeted user's hands. For example, boys and girls may prefer different
overmold
designs, just as men and women or adults and children may prefer different
overmold
designs especially configured for the respective sizes, strength and pressure
applied by
the hands of the respective users.
[0022] The preferred embodiments improve the control and comfort of the
toothbrush for
the user by providing a comfortable elastomeric covering about the handle of
the
toothbrush sized and shaped for the user's hand. A further benefit is provided
when the
toothbrush is an electric toothbrush. It is well-known that electric/sonic
toothbrushes
vibrate during use. This vibration can cause discomfort to a user, especially
when the
user is holding a rigid handle of the vibrating toothbrush. By providing a
comfortable
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elastomeric grip around the toothbrush handle, and not just selected portions
thereof, the
elastomeric overmold of the preferred embodiments provides a comfortable and
secure
grip of the toothbrush while reducing the vibration to the user as the
vibration is absorbed
by the elastomeric covering. Accordingly, a further benefit of the invention
is the
reduction of healthcare concerns caused to the hand, wrist and forearm of a
user by
absorption of the vibrations by the elastomeric overmold and resulting
reduction of
vibrations to the user's joints.
[0023] Referring now to the drawings, Figs. 1-3 illustrate an exemplary
embodiment of a
toothbrush 10 constructed in accordance with the invention. The toothbrush 10
includes
a core handle 12, a head 14 and a neck region 18 coupled therebetween. The
core handle
12, neck region 18 and head 14 may be integrally formed or alternatively
formed
separately and attached along the neck region 18 located between the head and
core
handle and coupling the two into a single unit. The head 14 has a base portion
20 having
a bristle mounting surface or face 22 from which a plurality of bristles 16
may be
attached, preferably via insertion into bores 24 (Fig. 3) distributed in the
base portion 20
across the face 22.
[0024] The core handle 12 is a generally cylindrical or tubular rigid plastic
shaft
extending from a shank 46 of the neck region 18 to a bottom 26 of the
toothbrush 10 at a
distal end thereof. While not being limited to a particular embodiment, the
toothbrush 10
is an electrical or sonic toothbrush with a bottom end cap 28 attached to the
core handle
12, preferably via a frictional fit. The end cap 28 is removable from the core
handle at
the bottom 26 thereof to expose a cylindrical channel for an energy source
(e.g., battery).
The end cap 28 preferably has a planar boundary (e.g., rim, wall, face,
surface) 30 that
allows the toothbrush 10 to stand upright when placed on a planar horizontal
surface.
[0025] Referring to Fig. 3, the core handle 12 is shown in tubular form
enclosing
electrically functioning elements 32 that are arranged within the elongated
shaft of the
core handle 12 and neck region 18. It is contemplated that the core handle 12
is not
limited to a cylindrical or tubular shape. For example, the core handle 12 may
be of other
appropriate shape, such as a variety of suitable polygons. The electrically
functional
elements 32 include an electrically operated functional unit 34 (e.g.,
vibration member
including an electric motor 36 coupled to an eccentric member 38), and an
electric supply
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unit 40 of conductive lines 42 connectible between the electric motor 36 and
an energy
source 44 (e.g., battery, rechargeable battery, connector to electrical
outlet). In some
embodiments, the electrically functional elements 32 may include one or more
piezoelectric elements. In some embodiments, the electrically functional
elements 32
may include more or fewer components as desired. In the embodiment as shown, a
switch 52 at a front side 54 of the toothbrush 10 is operably connectable to
the
electrically operated functional unit 34 to connect or interrupt power from
the energy
source 44 to the electrically operated functional unit 34 based on the
position of the
switch 52, toward or away from contact with the electric supply unit 40.
[0026] The core handle 12 is a hard plastic shaft comprising a rigid polymer
material. A
rigid polymer material provides strength and durability for portions of the
toothbrush 10
or dental instrument that will be subjected to stresses and forces associated
with gripping
the toothbrush 10 and using the toothbrush 10 for its intended dental purpose.
Strength
and durability will prevent these portions of the toothbrush 10 from cracking
or being
deformed under stress.
[0027] According to the preferred embodiments, the rigid polymer material may
include
any rigid thermoplastic material. Suitable rigid thermoplastics include
polycarbonates,
acrylonitrile butadiene styrene, polyamides, acetals, polysulfones, and
polypropylene.
The rigid polymer material may also include a rigid chemical cure or
thermocure polymer
material. Besides providing rigidity, strength, and durability, a chemical
cure or
thermocure polymer material also provides the advantages of being
autoclavable.
Exemplary rigid chemical cure or thermocure polymers include epoxies,
phenolics,
acrylates, urethanes and polyesters.
[0028] As can be seen in Figs. 1-3, the toothbrush 10 includes a thermoplastic
elastomer
(TPE) overmold grip 50 surrounding the core handle 12 where a person's hand is
expected to hold the toothbrush 10 during use. While not being limited to a
particular
construction, the overmold grip 50 is preferably assembled onto the rigid
plastic core
handle 12 by placing the core handle 12 in a suitable mold that seals off the
toothbrush 10
at the shank 46 and the bottom 26 of the shaft. A suitable TPE material is
then injected
into a suitably shaped mold cavity as understood by a skilled artisan.
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[0029] The thermoplastic elastomer overmold grip 50 is chemically bonded to
the rigid
plastic core handle 12 during the overmolding process that forms the overmold
grip 50
about the core handle 12. The elastomer overmold grip 50 and the core handle
12 are
chemically bonded during the overmolding process for the elastomer overmold
grip 50 by
the injection of the elastomer that is hot enough to chemically blend with the
material of
the core handle 12. In particular, the elastomer is injected at a temperature
hot enough to
cause an outer wall 48 of the plastic core handle 12 to soften or melt
sufficiently for
chemical blending of the outer wall with the hot elastomeric material of the
injection
overmold. As the elastomer cools, the chemical blend remains creating a
chemical bond
for holding the rigid plastic core handle 12 and the thermoplastic elastomer
overmold
grip 50 together.
[0030] The overmold grip 50 is preferably shaped for comfortable handing by
the user of
the toothbrush 10. It is understood that the invention is not limited to the
shape of the
overmold grips 50 and 60 (Figs. 4-6), but that the overmold grip 50, 60 may be
formed in
any shape that provides the intended user with a comfortable grip for use
during the
dental procedure. As such, the overmold grip 50, 60 may be formed by
conventional
means to a shape targeted towards the general size and shape of a user's hand
regardless
of the age or gender of the user. In addition, the overmold grip 50, 60 may
include
various configurations, such as different colors, patterns, designs, motifs,
etc. Further, in
some embodiments, the mold cavity that molds the overmold grip 50, 60 may be
adjustable to produce overmold grip 50, 60 of the various shapes, sizes,
colors, patterns,
designs, motifs, etc.
[00311 Figs. 4-6 depict a second example of the preferred embodiments with a
toothbrush
100 substantially similar to the toothbrush 10 discussed above. In particular,
the
toothbrush 100 shown in Figs. 4-6 is identical to the toothbrush 10 shown in
Figs. 1-3
except for the exterior shape of the overmold grip 60. The overmold grip 60 is
assembled
onto the rigid plastic core handle 12 and chemically bonded to the core handle
12 as
discussed above for the overmold grip 50. That is, the core handle 12 is
preferably
placed in a suitable mold that seals off the toothbrush 100 at the shank 46
and the bottom
26 of the core handle 12 shaft. However, the suitable mold is configured
differently to
form the overmold grip 60 which is different than the overmold grip 50. In
other words,
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the mold cavity of the mold that forms the overmold grip 60 has a different
shape, size,
color, pattern, design and/or motif than the mold cavity of the mold that
forms the
overmold grip 50. Regardless of the configuration of the mold cavity, the
elastomer is
injected at a temperature hot enough to cause the outer wall 48 of the plastic
core handle
12 to soften melt sufficiently for chemical blending of the outer wall and the
hot
elastomeric material of the injected overmold. The overmold grip 60 is formed
in an
alternative shape for comfortable handling by a user having a different gender
or age than
the targeted person or group of the first exemplary toothbrush.
[0032] According to the preferred embodiments, either of the toothbrushes 10,
100 is
preferably made by the same method. For example, the plastic core handle 12 is
molded
in a first mold as a shaft that is removed from the first mold subsequent the
molding. A
second mold used for manufacturing one of the overmold grips overmold grips 50
or 60
is selected from a plurality of the second molds, with each of the plurality
of second
molds having a different mold cavity such that an overmold (e.g., overmold
grip 50)
formed by one of the plurality of the second modes and an overmold (e.g.,
overmold grip
60) formed by another one of the plurality of second molds have different
configurations.
The plastic core handle 12 is placed into the selected one of the plurality of
second
molds. Then an overmold (e.g., overmold grip 50 or overmold grip 60) is formed
about
the plastic core handle 12 by injecting a material into the selected mold
cavity, and the
plastic core handle 12 and the respective overmold grip (e.g., overmold grip
50, overmold
grip 60) is removed from the selected mold cavity.
[0033] In certain embodiments, a kit may be provided that include a first
dental
implement with a first plastic core 12 and a overmold grip 50, and a second
dental
implement with a second plastic core 12 and a overmold grip 60. In this kit,
while the
plastic core 12 may be common among the dental implements, the overmold grips
50, 60
may have different configurations.
[0034] According to the preferred embodiments, the overmold grip 50, 60
comprises a
thermoplastic elastomer (TPE) material. The elastomeric material provides
increased
comfort and gripability to the handle of the toothbrush/dental instrument that
is gripped
by the user when using the toothbrush manually. Alternatively, the elastomeric
material
may include an elastomeric chemical cure or a thermocure polymer material for
the
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added advantage of autoclavability. Examples of thermoplastic elastomers
include
ethylene-propylene rubber, polyolefin elastomers, and synthetic rubber.
Examples of
suitable elastomer chemical cure or thermocure polymers include silicon
rubber, natural
rubber, synthetic rubber, and lower durometer urethanes. To provide optimal
comfort as
well as control benefits, the elastomeric material of the overmold grip
surface preferably
has a hardness durometer measurement ranging between Al 1 -A50 Shore hardness,
although materials outside this range may be used. A more preferred range of
the
hardness durometer rating is between A25-A40 Shore hardness.
[0035] While the invention has been described in detail and with reference to
specific
examples thereof, it would be apparent to one skilled in the art that various
changes and
modifications can be made therein without departing from the spirit and scope
thereof.
For example, the end cap 28 is preferably attached to the core handle 12 by
threaded,
snap fit or other frictional engagement, yet may alternatively be attached by
non-
frictional means such as an adhesive or magnets within the scope of the
invention.
Without further elaboration, the foregoing will so fully illustrate the
invention that others
may, by applying current or future knowledge; readily adapt the same for use
under
various conditions for service.
[0036] As used throughout, ranges are used as shorthand for describing each
and every
value that is within the range. Any value within the range can be selected as
the terminus
of the range. In addition, all references cited herein are hereby incorporated
by reference
in their entireties. In the event of a conflict in a definition in the present
disclosure and
that of a cited reference, the present disclosure controls.
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