Patent Description:
As an example, <CIT> discloses a silk brush including a base portion and a plurality of silk bristle tufts extending from the base portion, wherein bristles are obtained by combining two or more silk yarns that are bonded with silk components (i.e., sericin) and insolubilized.

<CIT> discloses a toothbrush comprising a plurality of tapered bristles having a straight portion and a taper portion, wherein abrasive particles are provided on the external surface of the taper portion and / or the straight portion of the bristles, so as to enhance plaque-scraping and dirt-removal functions of the bristles even in a narrow space such as an interdental portion. The bristles may be formed of one or more layers of a resin material.

<CIT> discloses a toothbrush comprising a vulcanized rubber and a medicated fibrous material which is incorporated in finely comminuted form throughout the rubber. Areas of medicated fibrous material are exposed during use for application on teeth and gums.

<CIT> discloses a toothbrush including a plurality of filaments made of an elastomeric material embedding a powder made of crushed plant fiber.

<CIT> discloses a toothbrush with a head with at least one bristle tuft and with a handle, wherein the bristles of the bristle tuft comprise a composition comprising a polymer and additive particles dispersed throughout the polymer.

<CIT> discloses a method for preparing bristles by using natural fibre-silk as raw material. The method comprises the following steps: applying a silk fibroin solution to the periphery of a core fibre followed by drying to form a covering layer onto the core fibre, and a post treatment including high-pressure steaming or soaking in alcohol to obtain silk bristles, wherein the effect of the post treatment is to harden and insolubilize the obtained bristles.

The present invention is a method of forming bristles comprising the steps of claim <NUM>. Embodiments of the invention are recited in the dependent claims.

It should be understood that the 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.

Referring first to <FIG>, an oral care implement <NUM> is illustrated. The oral care implement <NUM> is in the form of a manual toothbrush. However, the oral care implement <NUM> can take on other forms such as being a powered toothbrush, a tongue scraper, a gum and soft tissue cleanser, a water pick, an interdental device, a tooth polisher, a specially designed ansate implement having tooth engaging elements or any other type of implement that is commonly used for oral care.

The oral care implement extends from a proximal end <NUM> to a distal end <NUM> along a longitudinal axis A-A. The oral care implement <NUM> generally includes an elongated body <NUM> comprising a head <NUM>, a neck <NUM> and a handle <NUM>. The handle <NUM> is an elongated structure that provides the mechanism by which the user can hold and manipulate the oral care implement <NUM> during use. The handle <NUM> comprises a front surface <NUM> and an opposing rear surface <NUM>. The handle <NUM> is generically depicted having various contours for user comfort. More specifically, the handle <NUM> is bulbous shaped and has a larger diameter in a central region than near the proximal end <NUM> and neck <NUM>. Specifically, a region of the handle <NUM> that would normally be gripped by a user's thumb has a width that is greater than a width of the neck <NUM>. The handle <NUM> can take on a wide variety of shapes, contours and configurations.

The handle <NUM> is formed of a rigid plastic material, such as for example without limitation polymers and copolymers of ethylene, propylene, butadiene, vinyl compounds and polyesters such as polyethylene terephthalate. The handle <NUM> may include a resilient material, such as a thermoplastic elastomer, as a grip cover that is molded over portions of or the entirety of the handle <NUM> to enhance the gripability of the handle <NUM> during use. For example, portions of the handle <NUM> that are typically gripped by a user's palm during use may be overmolded with a thermoplastic elastomer or other resilient material to further increase comfort to a user.

The head <NUM> of the oral care implement <NUM> is coupled to the handle <NUM> and comprises a front surface <NUM> and an opposing rear surface <NUM>. The head <NUM> is formed integrally with the handle <NUM> as a single unitary structure using a molding, milling, machining or other suitable process. The handle <NUM> and the head <NUM> may be formed as separate components which are operably connected at a later stage of the manufacturing process by any suitable technique known in the art, including without limitation thermal or ultrasonic welding, a tight-fit assembly, a coupling sleeve, threaded engagement, adhesion, or fasteners.

The head <NUM> of the oral care implement <NUM> is provided with a plurality of tooth cleaning elements <NUM> extending from the front surface <NUM>. All of the tooth cleaning elements <NUM> appear to be the same. The tooth cleaning elements <NUM> include at least one bristle tuft comprising at least one bristle. The details of various structural forms for a bristle will be described in more detail below with reference to <FIG>.

A bristle tuft is a collection of bristles that are positioned together into a single tuft hole formed on the head <NUM>. Each bristle tuft may include, for example without limitation, only multi-component bristles, a combination of multi-component bristles and single-component (i.e., traditional) bristles, or only single-component bristles. The oral care implement <NUM> may include one or more bristle tufts that include exactly one multi-component bristle and a plurality of single-component bristles or one or more bristle tufts that include only multi-component bristles. The tooth cleaning elements <NUM> may all be formed as bristle tufts that are formed solely of multi-component bristles. Furthermore, the tooth cleaning elements <NUM> may include some bristle tufts that are formed solely of single-component bristles and some bristle tufts that are formed solely of multi-component bristles, and the single-component bristle tufts and multi-component bristle tufts may be positioned on the head <NUM> of the oral care implement <NUM> in an alternating or non-alternating fashion (i.e., alternating or non-alternating transverse rows of bristle tufts, alternating or non-alternating longitudinal rows of bristles, or even alternating or non-alternating tufts in each row).

As used herein, the term "tooth cleaning elements" is used in a generic sense to refer to any structure that can be used to clean, polish or wipe the teeth and/or soft oral tissue (e.g. tongue, cheek, gums, etc.) through relative surface contact. Common examples of "tooth cleaning elements" include, without limitation, bristle tufts, filament bristles, fiber bristles, spiral bristles, elastomeric protrusions, flexible polymer protrusions, combinations thereof and/or structures containing such materials or combinations. At least some of the tooth cleaning elements may be formed of rubberlike materials such as thermoplastic elastomers.

The tooth cleaning elements <NUM> can be connected to the head <NUM> in any manner known in the art. For example, staples/anchors, in-mold tufting (IMT) or anchor free tufting (AFT) could be used to mount the cleaning elements/tooth engaging elements or various combinations of stapled, IMT or AFT bristles can be practiced. In AFT, a plate or membrane is secured to the brush head such as by ultrasonic welding. The bristles extend through the plate or membrane. The free ends of the bristles on one side of the plate or membrane perform the cleaning function. The ends of the bristles on the other side of the plate or membrane are melted together by heat to be anchored in place. Any suitable form of cleaning elements may be used. Alternatively, the bristles could be mounted to tuft blocks or sections by extending through suitable openings in the tuft blocks so that the base of the bristles is mounted within or below the tuft block.

The head <NUM> of the oral care implement <NUM> comprises a plurality of tuft holes (not visible) formed therein. A plurality of tufts of bristles are positioned within and affixed to the head <NUM> within each of the tuft holes. Each of the tufts of bristles includes a plurality of bristles, which can be single strand bristles, double strand multi-component bristles, triple strand multi-component bristles, etc. or various combinations thereof. Thus, one tuft of bristles may include one double strand multi-component bristle and a plurality of single strand bristles or only double strand multi-component bristles or only triple strand multi-component bristles or a combination of single strand bristles, double strand multi-component bristles and triple strand multi-component bristles. Additionally, a single tuft hole may be filled with an elastomeric cleaning element or any of the other types of cleaning elements noted above. As noted above, at least one bristle tuft includes at least one multi-component bristle, which may be a double, triple or otherwise strand multi-component bristle. The details of the multi-component bristles will be discussed in more detail below with reference to <FIG>.

Although not illustrated herein, the head <NUM> may also include a soft tissue cleanser coupled to or positioned on its rear surface <NUM>. An example of a suitable soft tissue cleanser that may be used and positioned on the rear surface of the head <NUM> is disclosed in <CIT> to the assignee of the present application. The soft tissue cleanser may include protuberances, which can take the form of elongated ridges, nubs, or combinations thereof. The oral care implement <NUM> may not include any soft tissue cleanser.

As discussed herein, the bristle may also be referred to as a monofilament. As illustrated in <FIG> and 3A-3C, the bristle may be a single-component bristle <NUM>, <NUM> integrally formed from a composition comprising a polymer and a fibroin powder. As illustrated in <FIG> and <FIG>, the bristle may be a multi-component bristle <NUM>, <NUM> comprising a sheath component <NUM>, <NUM>, and a core component <NUM>, <NUM>, wherein either the sheath component or the core component may be formed from only the composition (polymer and fibroin powder), as discussed further herein.

Referring to <FIG> concurrently, a single-component bristle <NUM> will be described. The single-component bristle <NUM> extends from a base end <NUM> to a free end <NUM> along a longitudinal axis B-B. The single-component bristle <NUM> may also comprise a base portion <NUM>, a distal tip portion <NUM>, and an outer surface <NUM>. The base portion <NUM> extends from the base end <NUM> to a transition point TP1 and the distal tip portion <NUM> extends from the transition point TP1 to the free end <NUM>. The distal tip portion <NUM> transitions from the base portion <NUM> at the first transition point TP1. The base end <NUM> of the single-component bristle <NUM> may be anchored to the head <NUM> of the oral care implement <NUM> in any manner such as those described above, thereby leaving the free end <NUM> available to contact surfaces within an oral cavity during cleaning.

The cross-sectional geometry of the single-component bristle <NUM> may be circular. The cross-sectional geometry of the single-component bristle <NUM> may be ovular or polygonal - including triangular, rectangular, trapezoidal, heptagonal, hexagonal. Bristles having polygonal cross-sectional geometry may comprise longitudinal edges that allow the bristle to act as a wiping blade or squeegee element further enhancing the cleaning effect of the bristle on an oral cavity surface (e.g., tooth surface, gum surface) as discussed further herein below with reference to <FIG>.

Referring only to <FIG> and <FIG>, the base portion <NUM> of the single-component bristle <NUM> may have a substantially constant transverse cross-sectional area and the distal tip portion <NUM> may have a transverse cross-sectional area that decreases with increasing distance from the head <NUM> of the oral care implement <NUM>. According to the present invention, the phrase "substantially constant" means variation less than <NUM>%. The transverse cross-sectional area of the base portion <NUM> remains constant as measured from the base end <NUM> to the first transition point TP1 and the distal tip portion <NUM> has a cross-sectional area that decrease as measured from the first transition point TP1 to the free end <NUM>.

The decreasing transverse cross-sectional area in the distal tip portion <NUM> creates the single-component bristle <NUM> having a tapered section <NUM> extending from the first transition point TP1 to the free end <NUM> of the single-component bristle <NUM>. The free end <NUM> of the tapered single-component bristle <NUM> may culminate at an apex that is opposite the base end <NUM> of the single-component bristle <NUM> along the B-B axis. The taper may be continuous from the transition point TP1 to the free end <NUM> of the single-component bristle <NUM>.

Referring now only to <FIG>, a single-component bristle <NUM> will be described. The bristle <NUM> is similar to the bristle <NUM> except for the differences described herein below. The features of the bristle <NUM> that are described above with regard to the bristle <NUM> will not be repeated herein in the interest of brevity, it being understood that the description above with regard to the bristle <NUM> applies. Furthermore, features of the bristle <NUM> will be similarly numbered as similar features on the bristle <NUM> except that the <NUM>-series of numbers will be used. For features of the bristle <NUM> that are numbered but not described, it should be understood that the description of the similar feature in the bristle <NUM> applies.

The single-component bristle <NUM> may have a base portion <NUM> that has a substantially constant transverse cross-sectional area as well as a distal tip portion <NUM> that has a substantially constant transverse cross-sectional area. The distal tip portion <NUM> may have a substantially constant cross-sectional area where the free end <NUM> of the single-component bristle <NUM> is rounded rather than tapered. The single-component bristle <NUM> begins to be rounded at a second transition point TP2. The rounded free end <NUM> of the single-component bristle <NUM> may be hemi-spherical. Thus, the bristle <NUM> is identical to the bristle <NUM> except that the bristle <NUM> is not tapered but has a rounded free end.

Referring now to <FIG> and <FIG>concurrently, the single-component bristles <NUM>, <NUM> may be integrally formed from a single composition of a polymer <NUM>, <NUM> and a fibroin powder <NUM>, <NUM>. The polymer <NUM>, <NUM> may form a three-dimensional network in which the fibroin particles <NUM>, <NUM> are uniformly distributed throughout. The uniform distribution of the fibroin particles <NUM>, <NUM> throughout the polymer <NUM>, <NUM> may ensure that at least a portion of the outer surface <NUM>, <NUM> of the single-component bristles <NUM>, <NUM> comprises the fibroin particles <NUM>, <NUM> as well as the polymer <NUM>, <NUM>.

Referring now to <FIG> concurrently, a multi-component bristle <NUM> will be described. The multi-component bristle <NUM> extends from a base end <NUM> to a free end <NUM> along a longitudinal axis D-D. The multi-component bristle <NUM> may further comprise a base portion <NUM>, a distal tip portion <NUM>, and an outer surface <NUM>. The base portion <NUM> extends from the base end <NUM> to the distal tip portion <NUM> and the distal tip portion <NUM> extends from the base portion <NUM> to the free end <NUM>. The distal tip portion <NUM> transitions from the base portion <NUM> at a third transition point TP3. The base end <NUM> of the multi-component bristle <NUM> may anchored to the head <NUM> of the oral care implement <NUM>, thereby leaving the free end <NUM> uncoupled and available to contact surfaces within an oral cavity during cleaning.

The cross-sectional geometry of the multi-component bristle <NUM> may be circular. The cross-sectional geometry of the multi-component bristle <NUM> may be ovular or polygonal - including, triangular, rectangular, trapezoidal, heptagonal, hexagonal. Bristles having polygonal cross-sectional geometry may comprise longitudinal edges that allow the bristle to act as a wiping blade or squeegee element further enhancing the cleaning effect of the bristle on an oral cavity surface (e.g., tooth surface, gum surface) as discussed further herein with specific reference to <FIG>.

The base portion <NUM> of the multi-component bristle <NUM> may have a substantially constant transverse cross-sectional area and the distal tip portion <NUM> may have a transverse cross-sectional area that decreases with increasing distance from the head <NUM> of the oral care implement <NUM>. Stated another way, the transverse cross-sectional area of the base portion <NUM> remains constant as measured from the base end <NUM> to the third transition point TP3 and the distal tip portion <NUM> has a cross-sectional area that decrease as measured from the third transition point TP3 to the feed end <NUM>.

The decreasing transverse cross-sectional area in the distal tip portion <NUM> creates the multi-component bristle <NUM> having a tapered section <NUM> extending from the third transition point TP3 to the free end <NUM> of the multi-component bristle <NUM>. The free end <NUM> of the tapered single-component bristle <NUM> may culminate at an apex that is opposite the base end <NUM> of the single-component bristle <NUM> along the D-D axis. The taper is continuous from the third transition point TP3 to the free end <NUM> of the single-component bristle <NUM>. The base portion <NUM> and the distal tip portion <NUM> may both have decrease cross-sections as measured from base end <NUM> to the free end <NUM>, thereby creating a continuous longitudinal edge portion of the multi-component bristle <NUM>.

The multi-component bristle <NUM> comprises a core component <NUM> and a sheath component <NUM> that are coextruded to form the multi-component bristle <NUM>. Stated another way, the multi-component bristle <NUM> comprises the coextruded core and sheath components <NUM>, <NUM>. The sheath component <NUM> surrounds a first portion <NUM> of the core component <NUM> and a second portion <NUM> of the core component <NUM> protrudes from the sheath component <NUM> at a tip portion <NUM> of the multi-component bristle <NUM>. The second portion <NUM> of the core component <NUM> is therefore exposed whereas the first portion <NUM> of the core component <NUM> is not exposed but rather is entirely surrounded by the sheath component <NUM>. Thus, at least a portion of each of the core and sheath components <NUM>, <NUM> is visible from an exterior of the multi-component bristle <NUM>, and more specifically an entirety of the sheath component <NUM> is visible and the second portion <NUM> of the core component <NUM> is visible from the exterior of the multi-component bristle <NUM>.

Each of the core and sheath components <NUM>, <NUM> extend all the way to the base end <NUM> of the multi-component bristle <NUM>. The core component <NUM> extends from the base end <NUM> of the multi-component bristle <NUM> to the free end <NUM> of the multi-component bristle <NUM>. The sheath component <NUM> extends from the base end <NUM> of the multi-component bristle <NUM> to a terminal end <NUM> of the sheath component <NUM>. The second portion <NUM> of the core component <NUM> makes up between approximately <NUM>-<NUM>% of the total length of the multi-component bristle <NUM>, more specifically between approximately <NUM>-<NUM>% of the total length of the multi-component bristle <NUM>, and even more specifically between approximately <NUM>-<NUM>% of the total length of the multi-component bristle <NUM>. The exposed second portion <NUM> of the core component <NUM> may make up between approximately <NUM>-<NUM>%, and more specifically between approximately <NUM>-<NUM>% of the total length of the multi-component bristle <NUM>. Furthermore, the sheath component <NUM> extends approximately <NUM>-<NUM>% of the total length of the multi-component bristle <NUM>, more specifically approximately <NUM>-<NUM>% of the total length of the multi-component bristle <NUM>, and even more specifically between approximately <NUM>-<NUM>% of the total length of the multi-component bristle <NUM>, or between approximately <NUM>-<NUM>% or <NUM>-<NUM>% of the total length of the multi-component bristle <NUM>.

The multi-component bristle <NUM> has a cylindrical cross-sectional shape. Furthermore, the core component <NUM> has a cylindrical cross-sectional shape and the sheath component <NUM> has a ring-like shape that circumferentially and concentrically surrounds the core component <NUM> for at least part of the length of the core component <NUM>. Of course, the core component <NUM> can take on other polygonal shapes as desired and the shape of the sheath component <NUM> can likewise change so long as the sheath component <NUM> circumferentially surrounds the core component <NUM> for at least a portion of the length of the core component <NUM>.

Referring again to <FIG>, the sheath component <NUM> may be a secondary composition comprising polymer (e.g. nylon, PET, PBT, rubber) while being free of fibroin powder <NUM> and the core component <NUM> is formed from a composition comprising a polymer <NUM> and a fibroin powder <NUM> uniformly distributed throughout.

Referring now only to <FIG>, a multi-component bristle <NUM> is illustrated. The multi-component bristle <NUM> is similar to the multi-component bristle <NUM> except for the differences described herein below. The features of the multi-component bristle <NUM> that are described above with regard to the multi-component bristle <NUM> will not be repeated herein in the interest of brevity, it being understood that the description above with regard to the multi-component bristle <NUM> applies. Furthermore, features of the multi-component bristle <NUM> will be similarly numbered as similar features on the multi-component bristle <NUM> except that the <NUM>-series of numbers will be used. For features of multi-component the bristle <NUM> that are numbered but not described, it should be understood that the description of the similar feature in the multi-component bristle <NUM> applies.

The multi-component bristle <NUM> comprises a core component <NUM> and a sheath component <NUM> that are similar to the same components of the multi-component bristle <NUM> described above. The core component <NUM> may be a secondary composition that comprises polymer (e.g., nylon, PET, PBT, rubber) while being free of fibroin powder and the sheath component <NUM> may be formed from a composition comprising a polymer <NUM> and a fibroin powder <NUM> uniformly disturbed throughout. Thus, the multi-component bristle <NUM> has the opposite arrangement to the multi-component bristle in terms of composition. In the multi-component bristle <NUM> the sheath component <NUM> is free of fibroin powder (and may comprise only a polymer) and the core component comprises a polymer and a fibroin powder. In the multi-component bristle <NUM> the core component <NUM> is free of fibroin powder (and may comprise only a polymer) and the sheath component <NUM> comprises a polymer and a fibroin powder.

Although the multi-component bristles <NUM>, <NUM> are described herein as having two different components, three, four, five or more different components/layers can be used, each of which has a different oral care additive or any combination of the same and different oral care additives and lack thereof. A combination of different two component (or more) multi-component bristles can be utilized on the same oral care implement head wherein each component has different oral care agents/additives. For example, an oral care implement may include tooth cleaning elements disposed in transverse rows on the head. Each transverse row may include bristle tufts including multi-component bristles in one transverse row including different oral care additives than the multi-component bristles in each other or each adjacent transverse row. A virtually unlimited number of different combinations of the multi-component bristles described herein are possible.

Referring now to <FIG>, the bristles may have a polygonal or non-circular shape. Specifically, referring first to <FIG>, one example of a polygonal bristle <NUM> will be described. The bristle <NUM> has a polygonal shape with a triangular transverse cross-sectional area. The bristle <NUM> may be adequately described as having the shape of a triangular column. The bristle <NUM> may be formed of the same material(s) as the other bristles described herein, the difference being the specific shape of the bristle <NUM>. Thus, the bristle <NUM> may be single component or multiple component and may include a polymer and fibroin particles as described herein above.

The bristle <NUM> extends along a longitudinal axis C-C and comprises three longitudinal surfaces <NUM>, <NUM>, <NUM>. Each of the longitudinal surfaces <NUM>-<NUM> is elongated along the longitudinal axis E-E. The longitudinal surfaces <NUM> that are adjacent to one another intersect at a longitudinal edge <NUM>, <NUM>, <NUM>. Each of the longitudinal edges <NUM>-<NUM> is elongated along the longitudinal axis C-C. More specifically, the longitudinal surfaces <NUM>, <NUM> intersect at the longitudinal edge <NUM>, the longitudinal surfaces <NUM>, <NUM> intersect at the longitudinal edge <NUM>, and the longitudinal surfaces <NUM>, <NUM> intersect at the longitudinal edge <NUM>. Thus, each of the longitudinal edges <NUM>-<NUM> is an apex formed at the intersection of two adjacent longitudinal surfaces <NUM>-<NUM>. Each of the longitudinal edges <NUM>-<NUM> forms a wiping blade or squeegee that may enhance the cleaning or scraping effect of the bristle on an oral cavity surface such as a user's tooth.

The bristle <NUM> comprises a base portion <NUM> and a distal tip portion <NUM> that both have decreasing cross-sectional areas. Specifically, the base portion <NUM> may have a decreasing cross-sectional area as measured from a base end <NUM> of the bristle <NUM> to a transition point TP1, and the distal tip portion <NUM> may have a decreasing cross-sectional area as measured from the transition point TP1 to a free end <NUM> of the bristle <NUM>. Thus, the bristle <NUM> may be a fully tapered bristle (tapering along its entire length), a partially tapered bristle (tapering along part of its length similar to the bristle <NUM>), or the bristle <NUM> may be rounded.

As demonstrated in <FIG>, the transition point TP1 between the base portion <NUM> and the distal tip portion <NUM> may be smooth, thereby resulting in continuous longitudinal edges <NUM>-<NUM> that extend continuously from the base end <NUM> to the free end <NUM> without interruption by bumps, ridges, edges, points, or grooves. The bristle <NUM> illustrated in <FIG>, there are three longitudinal surfaces <NUM>-<NUM> and three longitudinal edges <NUM>-<NUM>. However, the number of longitudinal edges <NUM>-<NUM><NUM> and longitudinal surfaces <NUM>-<NUM> will depend on the cross-sectional geometry.

Referring briefly to <FIG>, a bristle <NUM> will be described. The bristle <NUM> is identical to the bristle <NUM> except that the bristle <NUM> has a square or rectangular cross-sectional shape and therefore the bristle <NUM> has the shape of a square column. Thus, the bristle <NUM> has four longitudinal surfaces <NUM>, <NUM>, <NUM>, <NUM> and four longitudinal edges <NUM>, <NUM>, <NUM>, <NUM> formed at the intersection of each two adjacent longitudinal surfaces <NUM>-<NUM>. Other than the additional surface and edge, the bristle <NUM> is identical to the bristle <NUM> and thus the description of the bristle <NUM> above with reference to <FIG> is applicable.

Referring briefly to <FIG>, a bristle <NUM> will be described. The bristle <NUM> is identical to the bristle <NUM> except that the bristle <NUM> has a hexagonal cross-sectional shape and therefore the bristle <NUM> has the shape of a hexagonal column. Thus, the bristle <NUM> has six longitudinal surfaces <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and six longitudinal edges <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> formed at the intersection of each two adjacent longitudinal surfaces <NUM>-<NUM>. Other than the additional surfaces and edges, the bristle <NUM> is identical to the bristle <NUM> and thus the description of the bristle <NUM> above with reference to <FIG> is applicable. Although only triangular, square/rectangular, and hexagonal shaped bristles are described herein with reference to <FIG>, it should be appreciated that any polygonal shape may be used. Thus, the bristles described herein may be pentagon shaped having five surfaces and five edges, heptagon shaped having seven sides and seven surfaces, octagon shaped having eight surfaces and eight edges, decagon shaped having ten surfaces and ten edges, etc..

The bristle is formed (in full or in part) from a composition comprising fibroin powder that is uniformly distributed throughout a polymer. The polymer present in the composition may be a thermoplastic organic polymer. The polymer may be a condensation polymer, such as polyester, polyamide, or a combination thereof. The average molecular weight of the polymer may be at least about <NUM>,<NUM>, and preferably at least <NUM>,<NUM>, to provide the strength and stiffness needed in a toothbrush bristle.

The polyamide may have a linear backbone and be produced by reacting a dicarboxylic acid with a diamine to form a linear condensation polyamide. Non-limiting examples of dicarboxylic acid include C6 to C12 aliphatic dicarboxylic acids, such as hexanedioic acid (adipic acid), heptanedioic acid (pimelic acid), octanedioic acid (suberic acid), nonanedioic acid (azelaic acid), decanedioic acid (sebacic acid), undecanedioic acid (brassilic acid), dodecanedioic acid, as well as aromatic dicarboxylic acids, such as terephthalic acid and isophthalic acid. Non-limiting examples of diamine may include linear aliphatic or cycloaliphatic diamine, such as ethylene diamine, trimethylene diamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, isophorone diamine, and <NUM>,<NUM>,-cyclohexanebis(methylamine). Non-limiting examples of diamine may also include linear aromatic diamine, such as phenylene diamine, and benzidine.

Non-limiting examples of polyamide include a nylon selected from nylon <NUM>,<NUM>; nylon <NUM>,<NUM>; nylon <NUM>,<NUM>. Nylon <NUM>,<NUM> refers to a linear polyamide that is the reaction product of a C6 diamine compound (e.g., hexamethylene diamine) and C6 dicarboxylic acid compound (e.g., adipic acid). Nylon <NUM>,<NUM> refers to a linear polyamide that is the reaction product of a C6 diamine compound (e.g., hexamethylene diamine) and a C10 dicarboxylic acid compound (sebacic acid). Nylon <NUM>,<NUM> refers to a linear polyamide that is the reaction product of a C6 diamine compound (e.g., hexamethylene diamine) and a C12 dicarboxylic acid compound (e.g., dodecanedioic acid).

The polyester may have a linear backbone and be produced by reacting a dicarboxylic acid with a diol. Suitable examples of dicarboxylic acids are previously listed. Non-limiting examples of diol may include C2 to C6 aliphatic diol, such as ethylene glycol, trimethylene glycol, butylene glycol, butanediol, pentamethylene, hexamethylene diol. The polyester may be the reaction product of terephthalic acid and ethylene glycol (i.e., polyethylene terephthalate "PET"). The polyester may be the reaction product of terephthalic acid and butanediol (i.e., polybutylene terephthalate "PBT").

The fibroin powder may be present in the composition by an amount ranging from about <NUM> wt. % to about <NUM> wt. % based on the total weight of the composition - including all sub-ranges and value there-between. The fibroin powder may be present in the composition by an amount ranging from about <NUM> wt. % to about <NUM> wt. % based on the total weight of the composition - including all sub-ranges and values there-between. In a preferred embodiment, the fibroin powder may be present in the composition in an amount ranging from about <NUM> wt. % to about <NUM> wt. % based on the total weight of the composition.

The fibroin powder may comprise particulates of fibroin protein. Fibroin is an insoluble protein present in the silk created by spiders and moths. Fibroin is collected by dissolving degummed silk material in at least one solvent, adding a coagulating salt to the aqueous fibroin solution. The fibroin is then be precipitated out of solution to form a gel, followed by dehydrating and drying the gel and pulverizing the solid fibroin by mechanical grinding into a fine fibroin powder that is non-fibrous and in particulate form.

The fibroin powder may be pulverized to obtain a predetermined particle size. The fibroin powder may have a particle size that is less than or equal to about <NUM> microns; alternatively less than or equal to about <NUM> microns. In a preferred embodiment, the fibroin powder may have a particle size that is less than or equal to about <NUM> microns. The fibroin powder may have a particle size ranging from about <NUM> microns to about <NUM> microns - including all sub-ranges and values there-between. The fibroin powder may have a particle size ranging from about <NUM> micron to about <NUM> microns - including all sub-ranges and values there-between. According to the present invention, the term "about" means +/- <NUM>% of the referenced value.

It has been discovered that adding fibroin powder to a composition used to form a bristle results in improved glideability as the bristle moves over a surface in an oral cavity (such as a tooth surface or gum surface). Furthermore, by uniformly distributing the fibroin powder throughout the polymer in the composition the bristle will continue to exhibit the desired level of glide-ability even as the outer surface of the bristle wears during use. Having fibroin powder distributed uniformly throughout the composition allows the fibroin to be present throughout the body of the bristle. Thus, unlike a surface coating, any wearing away of the outer surface of the bristle will only expose additional fibroin further contained in the body of the bristle, as demonstrated, for example, in <FIG>. Furthermore, it has been discovered that the composition used with a bristle having a polygonal cross-sectional geometry gives exceptional cleaning as the glidebility of the bristle with the composition coupled with the squeegee nature of the longitudinal edges allows for rapid and efficient collection of contaminants from the oral cavity.

Using fibroin particles may provide a smoother and more comfortable mouth feel during use of the bristles due to the pliancy characteristics that can reduce the friction and sting to the gums. Furthermore, fibroin particles may help absorb moisture and reduce the growth of bacteria due to its porous features. Finally, fibroin particles may facilitate teeth whitening when used in an oral care implement or toothbrush bristle as desribed herein.

The composition comprising the polymer and the fibroin particles may be formed by mixing fibroin powder with a prepolymer and a curing agent to form a precursor mixture, which is then processed in an extruder. The precursor mixture may be formed before being fed to an extruder by adding the fibroin powder, the prepolymer, and the curing agent together in a pre-mix step that takes place in a mechanical mixer - e.g., a banbury mixer. The precursor mixture can also be formed in the extruder by simultaneously adding the separate fibroin powder to the prepolymer and curing agent.

The prepolymer of the precursor mixture may be a polymer having a number average molecular weight ranging from about <NUM> to about <NUM>,<NUM> and have carboxylic acid groups (COOH) at the terminal groups of the polymer with an average COOH functionality of two. The backbone of the prepolymer may correspond to the final polymer type being desired - i.e. for polyester polymer the prepolymer has a polyester backbone; for polyamide polymer the prepolymer has a polyamide backbone. The curing agent may comprise low molecular weight di-functional monomer that can react with the carboxylic acid groups present on the prepolymer, thereby curing the prepolymer to form the final polymer. For polyester, the curing agent may comprise the aforementioned diol compounds and for polyamide, the curing agent may comprise the aforementioned diamine compounds.

After forming the precursor mixture, it may be then fed to an extruder. The extruder may be a single screw extruder or a twin screw extruder. The extruder may comprise one or more processing zones - including, but not limited to, a feed zone, a processing zone, and shaping die. The feed zone collects the precursor mixture as it is fed to the extruder. The processing zone may comprise a plurality of sub-zones. Non-limiting examples of sub-zones include a melting zone, a metering zone, and a degassing zone. As the precursor passes through the processing zone, a plurality of heating elements that heat the precursor mixture to a temperature ranging from <NUM> to about <NUM>. The temperature is above both the melting temperature of the prepolymer thereby melting the prepolymer into a molten state. As the screw(s) of the extruder rotate, the molten precursor is further mixed as it is conveyed toward the shaping die. Additional mixing may further ensure a uniform distribution of the fibroin powder in the final composition. As the molten precursor continues through the extruder, the processing temperature reaches or is slightly above the reaction temperature of the prepolymer and curing agent, thereby causing the free COOH groups present on the prepolymer to react with the curing agent and form the final polymer. The cured or semi-cured composition continues through the extruder and reaches the shaping die.

The shaping die may comprise at least one outlet having a predetermined shape for the composition to pass through. The predetermined shape may be circular, ovular, or polygonal. Non-limiting examples of polygonal shapes include triangular, rectangular, trapezoidal, pentagonal, and hexagonal. The shape of the die outlet may control the traverse cross-sectional geometry of the resulting bristle. The may have a transverse cross-section that is circular, ovular, or polygonal. Non-limiting examples of polygonal cross-section geometries include triangular, rectangular (including oblong rectangle and squares), parallelogram, trapezoidal, pentagonal, or hexagonal. As the composition passes through the shaping die, it forms a continuous bulk filament of the composition having a predetermined cross-sectional area dictated by the dimensions of the die opening.

Processing concerns related to the extruder may limit how small the cross-sectional area of the extruded bulk filament may be at the time of leaving the shaping die. The bristle, however, may require a maximum cross-sectional area that is a fraction of the cross-sectional area of the bulk filament as it leaves the shaping die. Thus, a spin drawing step that not only elongates the bulk filament but simultaneously decreases the cross-sectional area to a value that is appropriate for the bristle - thereby producing a bristle filament. The spin drawing step may be performed on a spinneret while the bulk filament is at or above the melting temperature of the polymer in the composition. After being spun-drawn by the spinneret, the resulting bristle filament may be collected onto a feed roll.

Claim 1:
A method of forming bristles (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) comprising:
a) forming fibroin particles (<NUM>, <NUM>, <NUM>, <NUM>) by dissolving a degummed silk material in at least one solvent to form a fibroin solution, adding a coagulating salt to the fibroin solution, precipitating a fibroin precipitate from the fibroin solution to form a gel, dehydrating and drying the gel to form solid fibroin, pulverizing the solid fibroin by mechanical grinding into fine and non-fibrous fibroin particles (<NUM>, <NUM>, <NUM>, <NUM>);
b) mixing the fibroin particles (<NUM>, <NUM>, <NUM>, <NUM>) into a polymer resin (<NUM>, <NUM>, <NUM>, <NUM>) to form a mixture; and
c) forming a plurality of bristles (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) from the mixture.