An improved cosmetic and healthcare brush

BACKGROUND OF THE INVENTION The present invention relates to an improved cosmetic and/or healthcare brush, preferably a hair brush, as well as a cosmetic and/or healthcare dispenser comprising the brush.

In the cosmetic and healthcare field, particularly in the application of formulations to hair, such as mascara, it is desirable to obtain both an attractive separation of the hair or skin, preferably eyelashes, and hair as well as a high volume and body of the hair or skin, preferably eyelashes, and hair. To date this has generally required the use of two different brushes, one designed to provide separation, and the other to provide volume.

Recently molded brushes have been developed which provide however a good compromise between both objectives. Such molded brushes are known, for example, from EP1161159.

However for the case of Twisted Wire Brushes (TWB), it is still difficult to produce brushes having both favorable separation and volume properties. For example, EP1389436B1 discloses a brush having good combing and separation due to its wedge-shaped tips. Nonetheless, this brush does not provide high volume because a standard wiping action with this brush wipes off too much of the standard formulation in this action. Therefore it is desirable to provide an improved TWB cosmetic and healthcare brush providing both high separation and volume in one single TWB brush. In conclusion, it would be desirable to have an improved TWB cosmetic and healthcare brush providing favorable separation and volume of hair or skin, preferably eyelashes, and hair. SUMMARY OF THE INVENTION

Starting from this state of the art, it is an object of the invention to provide an improved cosmetic and healthcare brush providing both high separation and volume.

According to the invention, these objects are achieved by a cosmetic and healthcare brush for applying a cosmetic and healthcare mass onto the hair or skin, preferably eyelashes, comprising: (i) a core section of at least two mutually-twisted together wire segments, (ii) a bristle section comprising bristles secured between said two mutually-twisted together wire segments, wherein at least a portion of the bristles end in a tapered cross-section, and the bristles have an outer portion made of a first, softer material and an inner portion made of a second, harder material wherein the bristles flare outwardly in various directions from said core section and the cross-sections of the bristles vary in shape lengthwise along the bristle.

The inventors have surprisingly found that said cosmetic and healthcare brush provides both favourable separation and volume properties. Because the bristles flare outwardly in various directions, their tips are closely packed together with little free spacing between them. This high packing density of the tips means that the hairs are unable to pass through the tips into the interior of the brush. Therefore it is necessary to have at least a portion of the bristles end in a tapered cross-section as in the molded brush of EP‘436B1. In various embodiments, at least about 50, specifically, 75, more specifically 90 %, most specifically substantially all of the bristles of the brush of the present invention end in a tapered cross-section. With a standard wiping action, therefore a fairly high amount of standard cosmetic and healthcare formulation will be wiped off.

In the brush of the present invention, the cross-sections of the bristles vary in shape lengthwise along the bristle, which then provides for (indented) recesses or other similar reservoirs for cosmetic and healthcare along the length of the bristles, particularly in the active region near the tapered tip. The cosmetic and healthcare residing in these recesses or reservoirs will not be wiped off during the standard wiping action.

In a first embodiment of the brush of the present invention, at least a portion of the bristles have recesses, wherein preferably the recesses are distributed over the entire length of their bristle, preferably uniformly distributed over the entire length. In selected embodiments of the brush, at least about 50, 75, 90% or essentially all of the bristles have recesses. These recesses advantageously provide the just-discussed reservoirs for the cosmetic and healthcare to reside in. The filaments of the bristle are conveniently manufactured having recesses distributed over the entire filament length. When the filaments are cut and mounted in the brush, the recesses are then randomly distributed over the lengths of the filaments of the bristle relative to its free end. Therefore it is often important that the recesses are uniformly distributed over the bristle length, so that at least some of the bristles in the active region will contain recesses to act as reservoirs for cosmetic and healthcare there. In addition, it will therefore be preferred that the recesses have sufficient size to act as reservoirs, and thus they will have minimum axial lengths measured along the axis of the bristle of between about 0.05 and about 0.30, preferably between about 0.1 and about 0.2 mm. In certain embodiments, the recesses will have substantially round, elliptical, oval, rectangular, triangular or square circumferences and often with a funnel-like narrowing profile towards the interior or core of the bristle. Typically the geometric form of the recess will be stretched along the axis of the bristle in the axial direction in relation to the geometric form of the stamp used to create the recess. This is because the bristle is moving through the die during the stamping or embossing step. Therefore in preferred embodiments the recesses are distributed non-randomly and substantially regularly with substantially constant spacing between recesses, preferably of about + 20, more preferably 10, most preferably 5% variation. In some more specific embodiments, the maximum distance between recesses is between about 0.2 to about 2.0 mm.

In certain preferred embodiments of the previous first embodiment, at least a portion of the recesses are located along the bristle length within a distance of 3 mm, preferably 2 mm, from the far end of the tapered end of the bristle (“free” bristle end). Locating the recesses within such a distance from the tapered end provides the advantage that the double action of separating and providing volume takes place within the active region of the bristle near its end. In various embodiments, at least one recess or a partial recess is located within one of these distances from the bristle end.

In certain other preferred embodiments of the previous first embodiment, a minimum separation distance between the recesses, measured from the starting point to starting point of adjacent recesses, along their bristle is from about 0.1 mm to about 1.0 mm, preferably about 0.2 to about 0.8, more preferably about 0.3 to about 0.6. The“starting point” of a particular recess is a point along the contour of the recess that is closest to far end of the tapered end of the bristle (“free” bristle end) on which the recess is located. This minimum spacing measured along the longitudinal axis of the bristle ensures that the recesses are effective so that they are not partially or fully removed by the taper.

In some embodiments of the cosmetic and healthcare brush of the present invention, the portion of the bristles ending in a tapered cross-section have a taper length of from about 0.2 mm to about 1 mm. If the taper length is too short, the bristles are not effective in separating and combing, and they would only bend the lashes but not comb them. In contrast, if the taper length is too long, then the bristles are not stiff or stable enough to provide separation. Therefore a taper length of from 0.2 mm to about 1 mm combined with typical fiber diameters and materials has proven to provide an effective optimization of these effects.

In certain embodiments of the brush, the bristles ending in a tapered cross- section are ending in a chisel-like taper consisting of either a single (chisel- like configuration) or a double angle (roof-like configuration) cut tangential to the axis of the bristle core. It is to be understood that the tapered end-section and wedge shapes need not necessarily be produced by cutting the filament or bristle, but the tapering and wedge-shape may be alternatively produced by a grinding process, for example, as is known from WO’436 A1. The wedge angles a (relative to the longitudinal axis of the bristle) of the bristles may vary from about 80° to approximately 89° in one embodiment. Smaller wedge angles a between about 5° and about 80° are also feasible in other embodiments. Such single or double angle cuts are relatively inexpensive to produce. For small diameter fibers, a single angle cut will often be sufficient and economical, whereas larger diameter fibers will generally be most effective with a double angle cut. Free ends of the mascara brush that have a roof or chisel-like configuration lead to the optimization of the property pair of a separation on the one hand and combing effect on the other hand. Alternately, free ends of the bristles that are wedge-shaped in cross section may be implemented also by bevelling the ends of the bristles.

In some embodiments of the brush having recesses, the first recess located closest to the bristle end along a bristle is located at a distance of between about 0.1 to about 1.0 from the bristle end, preferably about 0.2 to about 0.8, more preferably about 0.3 mm to about 0.6 mm, even more preferably within the tapered length, most preferably a partial recess within the tapered length. Locating the first recess in this region close to the bristle end provides the advantage of the earlier-discussed double action within the active region of the bristle.

In certain embodiments of the bristle, the capacity of the entire AR, FR or even bristle (FR and CFR) is increased due to the presence of the recesses 40. In specific embodiments, the surface roughness, Rz, which is also referred to as roughness depth, as determined in accordance with DIN EN ISO 4287/4288 of the entire AR, FR or even bristle (FR and CFR) is increased due to the presence of the recesses 40. In specific embodiments, the surface roughness (Rz) is greater than 6.3, preferably 6.5, more preferably 7, most preferably 10 pm.

In certain embodiments of the brush having recesses, the bristle cross-section is non-cylindrical within and adjacent to the region of the recess. Advantageously the thin flexible fibers will be indented from both sides, for example, by means of opposed rollers or calendars through which the fiber travels. Such indentation processes will then typically impart the bristle with a non-cylindrical cross-section around the recess. For the same reason, in some more preferred embodiments, the recesses on a bristle are located substantially opposed to one another, preferably so as to confer the bristle with a substantially hour glass or dumbbell shaped cross-section in the region of the bristle containing said recesses, more preferably so as to confer the bristle with a cross-sectional profile similar to that of goat hair. Goat hair is a natural hair having both hard and soft components, and advantageously this natural hair has a non-round cross-section. Goat hair generally has a fine point and a uniform body that, under a microscope, appears to consist of tapering, individual scales that are attached end to end. There are small pockets where these scalelike shapes meet that allow cosmetic or healthcare masses to be trapped and held until use. This combination of properties ensure that the fiber ends flare out and do not follow the helix of the brush, as described in EP0250680A1. The inventors have found that the same effect may be achieved with 2-component bristles having non-round cross-sections and recesses as in the present invention.

In some embodiments of the brush of the present invention, at least a portion, preferably the majority, more preferably all, of the bristles ending in a tapered cross-section have at least one, preferably more than one, fibrous extension located with the tapered length, most preferably at the bristle free end. This means that the physical connection between the fibrous extension and the bristle generally occurs within the tapered length and specifically may occur within a distance of about one average bristle diameter from the free end. The provision of such fibrous extensions provides several advantages over bristles not having such fibrous extensions. The normal bristles may pick up large volumes of mascara to be dispensed; however, they have difficulty to subsequently pay off the large volumes of mascara, a function which take place primarily at the surface, due to the thickness, stiffness and hardness (rigidity) of normal bristles. In contrast, the thin, flexible and soft fibrous extensions of the present invention have a much superior ability to pay off large volumes of mascara. Due to their thin, flexible and soft nature, the fibrous extensions are able to adjust, bend down, and lay on the surface of the bristle to efficiently aid the transfer of mascara from the bristle to the hair and then to subsequently recover. In certain more specific embodiments, the fibrous extension comprises primarily either the first, softer material, or the second, harder material, preferably the second, harder material. Alternatively, it may be both the first, softer material and the second, harder material. In some preferred embodiments it is the second, harder material, optionally together with some amount of the first, softer material (for example, primarily PBT with a lesser amount of TPE) as it has been found that such fibrous extensions are readily produced using the filaments described in the present application together with the grinding method to create fibrous extensions. It is noted that the thicker the first, softer material, the more likely that it would comprise part of the fibrous extension.

In other more specific embodiments, the fibrous extensions are embodied so as to pick up a portion of a cosmetic and healthcare formulation when the cosmetic and healthcare brush is dipped into a cosmetic and healthcare formulation and a residue of the picked up portion of the cosmetic and healthcare formulation remains on the fibrous extension after subsequent wiping of the cosmetic and healthcare brush. These characteristics provide the effect that the brush not only efficiently picks up - but also retains - a portion of the formulation so that it may subsequently be transferred to the hair or skin. The fibrous extensions are very floppy due to their flexibility and softness so that there is no great force on them removing formulation during the wiping action. Therefore bristles having fibrous extensions are superior to ones without in retaining formulation on them during wiping actions.

In still other more specific embodiments, the fibrous extensions are selected to be suitably soft and flexible so that they may bend and substantially lay on the surface of the tapered end of the bristle, preferably while retaining the residue of the picked up portion of the cosmetic and healthcare formulation remains on the fibrous extension after subsequent wiping of the cosmetic and healthcare brush. These properties provide significant benefits in making it possible to pay off large volumes of formulation onto hair, as was described earlier.

One aspect of the present invention is a cosmetic and healthcare dispenser comprising the cosmetic and healthcare brush of the present invention, particularly one of any one of the previously described embodiments, preferably a cosmetic and healthcare dispenser containing cosmetic and healthcare. Such a cosmetic and healthcare dispenser will be imparted with the advantages of the brush of the present invention.

One skilled in the art will understand that the combination of the subject matters of the various claims and embodiments of the invention is possible without limitation in the invention to the extent that such combinations are technically feasible. In this combination, the subject matter of any one claim may be combined with the subject matter of one or more of the other claims. In this combination of subject matters, the subject matter of any one brush claim may be combined with the subject matter of one or more other brush claims or the subject matter of one or more dispenser claims or the subject matter of a mixture of one or more brush claims and dispenser claims. By analogy, the subject matter of any one brush claim or dispenser claim may be combined with the subject matter of one or more other brush or dispenser claims or the subject matter of one or more brush claims or the subject matter of a mixture of one or more brush or dispenser claims and brush claims. By way of example, the subject matter of any one claim may be combined with the subject matters of any number of the other claims without limitation to the extent that such combinations are technically feasible.

One skilled in the art will understand that the combination of the subject matters of the various embodiments of the invention is similarly possible without limitation in the invention. For example, the subject matter of one of the above-mentioned brush embodiments may be combined with the subject matter of one or more of the other above-mentioned dispenser embodiments or vice versa without limitation so long as technically feasible.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail hereinafter with reference to various embodiments of the invention as well as to the drawings. The schematic drawings show: Fig. 1 shows a schematic view of an embodiment of a brush according to the invention.

Fig. 2 (a) and (b) shows the individual regions of a bristle.

Fig. 3 shows a schematic view of the cross-sections of the bristles varying in shape lengthwise along the bristle and recesses located substantially opposed to one another so as to confer a substantially hour glass or dumbbell shaped cross-section.

Fig. 4 shows bristles ending in a chisel-like taper and having recesses located along the length of the bristle, a first recess located near the tapered end, and a fibrous extension at the bristle end.

Fig. 5 shows a schematic view of fibrous extensions at the bristle end of the chisel-like taper.

Fig. 6 shows the interaction between a fibrous extension and lashes showing pay off (a) starting with the first contact of the lashes with the fibrous extension and then (b) how the lashes move the fibrous extension so that it bends and substantially lays on the surface of the tapered end of the bristle.

Fig. 7 shows the interaction between a fibrous extension and a wiper orifice during a wiping action such that a residue of the picked up portion of the formulation remains on the fibrous extension during wiping of the brush due to the interaction of the orifice primarily with the stiffer bristle rather than with the floppy fibrous extension.

DETAILED DESCRIPTION OF THE INVENTION DEFINITIONS As used in the specification and claims of this application, the following definitions, should be applied:

"a", "an", and "the" as an antecedent may refer to either the singular or plural unless the context indicates otherwise.

“diameter” refers to the diameter of a circular bristle or filament as measured by a micrometer screw. For non-circular (e.g. polyhedral or irregularly-shaped) bristles or filaments the“diameter” is the smallest diameter of a circle within which the cross-section of the non-circular bristle or filament would fit. This may be determined experimentally by determining the smallest inner diameter of a tube within which the non-circular bristle or filament would fit.

“Tapered” refers to a diminishment or reduction in thickness of a bristle towards the free end of the bristle (“bristle end”). Thus there may be a tapering of the cross-section, and a“tapered end-section” refers to the section near the bristle end (within a length of preferably 2, more preferable 1.5, most preferably 1 mm from the free end of the bristle) and also including the bristle end in which the thickness and cross-section are substantially continuously or preferably continuously decreasing toward the bristle end. The“taper length” refers then to the length along the bristle axis of the tapered end-section.

“The cross-sections of the bristles vary in shape lengthwise along the bristle” means that the diameter changes (thinner/thicker) and/or the geometric form (e.g. C vs. DB) varies over the entire length of the bristle (CFR and FR regions). This variation may not be continuous but may be discrete instead, for example, typically resulting from the presence of recesses along the entire length of the bristle. For example, a recess may locally cause a DB or other non-cylindrical cross-section as opposed to a C or other cylindrical cross- section in regions of the bristle away or remote from any recesses. In many embodiments, the recesses occur at a substantially regular spacing along the entire length of the bristle, and thus resulting in corresponding substantially regular variations of the shape of the cross-section of the bristle lengthwise along the bristle. In various embodiments, at least one, specifically two, more specifically three, or more variations in the geometric form of the cross-section occur over the entire length of the bristle (CFR and FR regions). Bristles merely having tapered end-sections are specifically excluded from this definition. Thus in various embodiments, at least three, specifically four, more specifically five, or more variations in the diameter of the cross-section occur over the entire length of the bristle (CFR and FR regions).

A“cross-sectional profile similar to that of goat hair” is one that is substantially similar in appearance and performance to that of the goat hair cross-sectional profile as described here earlier and in section 4.1.3.9 Ziegenhaar on p. 143 in the handbook,„Biirsten und Pinsel” by Ernst Bock, published in 1983 by the Fachbuch Verband der Deutschen Pinsel- und Biirstenhersteller e.V., Bechhofen, Germany (OCLC-NR: 74634224) or in Fig. 31 , p. 63 of“Guide to the Identification of Animal Fibres” 2nd ed., by H. M. Appleyard, published in 1978 by Wira, Leeds, UK (ISBN 090082011X 9780900820113), as well as the goat hair images available on the internet from the public textile image collection from CSIRO, the Australian science research organization: http://www.scienceimage.csiro.au/librarv/textile/·

A“recess” refers to a small space set back from the surface of the bristle, which may be in the form of an indentation, depression or cleft. The recess is generally not specifically limited as to how it is produced, and it may be produced by means of indention or embossing. However the method of WO2016/016436 A1 and its fine depressions are nonetheless specifically excluded in which filaments are extruded with fine clay or silica additives having a particle size of from 0.01 to 100 pm and then ripped at random from the surface by grinding to form random fine depressions resulting from the ejection of the 0.01 to 100 pm diameter particles.

A“partial recess” is a recess that is only partially present on the bristle as a portion of the recess has been cut away in cutting the bristles to their desired length or in providing them with a tapered profile.

A“fibrous extension” is a flexible extension of a bristle comprising, consisting essentially of, or consisting of a plastic or polymeric material, typical the synthetic material of which the bristle is composed of. The fibrous extension comprises one or more fine filaments extending from the bristle surface, and thus they often have a hair-like appearance. For example, it may be one or both materials in 2-component (2K) bristles, for example, those consisting of a core and a sheath. Such fibrous extensions are often referred to as“flagging” in the art, and flagged bristles, are often actually split at the ends and look fuzzy, for example, like split hairs. The split ends create more surface area and allow a brush to hold more material (e.g. paint or cosmetic or other material) and to release the material more smoothly, thus giving a cleaner finish or application. With natural fiber, slagging is an operation which literally splits hairs. Hog bristle has a natural 'flag' in it, which is due to the splitting of the medulla at the tip of the bristle into a number of fine filaments which make up the 'flag'. Thus the fibrous extensions of the present invention are to be distinguished from protruding inorganic particles known in the art, as in WO2010/016436 A1.

A“fibrous extension located within the tapered-end section” means that the base or fixed end of the fibrous extension on the bristle (connecting end between the fibrous extension and the bristle) is located substantially, preferably entirely, within the tapered end-section. Thus in the present invention preferably the minority, more preferably essentially none, most preferably none of the fibrous extensions have their base or fixed end located substantially outside, preferably outside, of the tapered-end section, for example, outside of the active region (AR) and within the remaining base region (BR) or in the central fixing region (CFR). In various embodiments none are located more than 2, preferably 1.5, more preferably 1 mm from the free end.

Numerical values in the present application relate to average values. Furthermore, unless indicated to the contrary, the numerical values should be understood to include numerical values which are the same when reduced to the same number of significant figures and numerical values that differ from the stated value by less than the experimental error of the conventional measurement technique of the type described in the present application to determine the value.

Fig. 1 shows an embodiment of a cosmetic and healthcare brush 1 according to the present invention for applying a cosmetic and/or healthcare mass, preferably mascara, onto the hair or skin, preferably eyelashes 70. It may be seen that the brush 1 comprises (i) a core section 10 and (ii) a bristle section 20, which comprises bristles 22, wherein at least a portion of the bristles end in a tapered end-section 30. It can be seen that the bristles 22 flare outwardly in various directions from the core section 10 so that their tips are closely packed together with little intervening free space between them. The brush 1 may have a shape that is either rotationally symmetric or non-rotationally symmetric, and the brush 1 may often fit into a tube having a maximum diameter of 12 mm.

The bristles 22 of the present invention are not specifically limited and may include synthetic fibers of various cross-sections such as solid round, hollow round, tapered, solid round tapered, quadrilobal, trilocular, synthetic goat hair, crimped, spoked hollow, trilobal, oval, star-shaped, square, X-shaped, longitudinally grooved, C-shaped, cross-shaped, triangular outer face shape with rounded edges, Y-shaped, H-shaped, honeycomb or a fourfold, cloverleaf type pattern in such a way that the bristle appears like a piece from a puzzle. In a preferred embodiment, the cross-section is solid round as such a cross-section is readily manufactured with fibers having one polymer composition for a core and another polymer composition for the surrounding sheath. Typical average diameters of bristles are between about 4 and about 10 mils or between about 0.075 and about 0.35, preferably about 0.1 and about 0.3, more preferably about 0.15 and 0.25 mm. Thus in one embodiment the filament used to manufacture the bristle has a thickness such that it would fit into a circumference of a circle of from about 0.1 to about 0.4 mm.

To explain the invention, the individual regions of a bristle will be initially defined below making reference to FIG. 2. FIG. 2 shows a bristle 22 having a central fixing region (CFR), which is fixed between the two mutually-twisted together wire segments 12, and the remaining flexible regions (FR).

The flexible regions (FR) are divided further into an active region (AR), which is embodied to be suitable to come into contact with the eyelashes 70 of a user. The remaining base region (BR) will generally be too deep into the interior of the brush and will not come into contact with eyelashes 70 of a user during application of mascara. Both regions, AR and BR, however will come into contact with mascara taken up from the wiper 80 prior to application of mascara to the eyelashes 70. The FR may be from about 2 to about 5 mm in length, and the AR may be then vary from about 0.8 to about 2 mm in length, respectively. Thus the AR may typically be from about 40% of the FR for short bristles to about 20% of the FR for longer bristles.

The bristle 22 may have regions of different cross-sectional shape. The cross- sectional shape of the bristle 22 in the longitudinal direction can thereby change one or several times. The bristle 22 may consist e.g. of sequential regions, with one or more round or circular (C), oval, polygonal (in particular square, triangular, rectangular, or octagonal), Y-shaped, crossed or star- shaped, annular, arc-shaped, circular or other earlier described segment- shaped cross-sections. Due to the presence of recesses 40 along the bristle 22, other cross-sectional shapes such as substantially hourglass or dumbbell (DB) may be created, for example, by embossing, so as to yield a cross- sectional profile similar to that of goat hair.

Fig. 3 shows a schematic view of the cross-sections 28 of the bristles 22 varying in shape lengthwise along the bristle 22. For example, recesses 40 may be located substantially opposed to one another so as to confer a substantially hour glass or dumbbell (DB) shaped cross-section. Typical minimum cross-sectional diameters of the DB will be between about 0.05 and 0.125 mm and maximum cross-sectional diameters will be between about 0.15 and 0.35 mm. In other regions lacking the recesses 40, the cross-section 28 is cylindrical (C) and bristle diameters will typically be between about 0.1 to about 0.2 mm.

The recesses 40 on the bristles 22 according to the present invention may be made by conventional methods such as indentation, etching, or embossing, such as with embossing rollers. Typically recesses will be created on the fibers before they are cut to length or profiled in the manufacture of the bristles. Typical geometries of the recesses 40 include substantially quadratic, elliptical, oval or circular shapes, and dimensions of the recesses include lengths (x) along the axis of the bristle of between about 0.05 and about 0.18 mm, preferably between about 0.1 and about 0.14 mm. Typical widths of the recesses (y) of the recesses will vary from about 0.03 to about 0.10, preferably from about 0.05 to about 0.07 mm. Typical recesses will have an average maximum depth (z) which is about 10 to about 40, preferably about 25 to about 35 % of the diameter of the bristle 22. In other embodiments, the average maximum depth (z) is about 0.02 to about 0.12, preferably about 0.05 to about 0.08, most preferably about 0.06 mm.

The bristles 22 in the embodiment of Fig. 3 are seen to have an outer portion 24 made of a first, softer material and an inner portion 26 made of a second, harder material. The use of said different materials for one and the same bristle 22 has turned out as being very advantageous for indenting or embossing the above mentioned structure into the bristle 22, so the combination of using two different materials and indenting or embossing is clearly preferred. A particular advantage is to make the outer portion 24 of the softer material. This allows a lasting indentation or embossing while the hard core of the bristle determines the main direction in which the bristle extends, even after indentation or embossing. At least some of the bristles of the cosmetic and healthcare brush 1 according to the invention have an outer portion 24 made of a first, softer material and an inner portion 26 made of a second, harder material. In various embodiments of the brush 1 , more than 50, 75, 90%, or essentially all of the bristles 22 have an outer portion 24 made of a first, softer material and an inner portion 26 made of a second, harder material. In some embodiments such two component filaments are produced by co-extrusion. In a specific embodiment, the inner portion 26 comprises PBT and optional additives and the outer portion 24 comprises a thermoplastic elastomer and optional additives.

Typical additives are stabilizing or processing agents, colorants, or fillers common in the plastics injection molding industries or may be conditioning, anti-static, antimicrobial additives more common in the make-up industry.

The terms “softer” and “harder” refer to the relative hardness of the two materials, and polymer or plastic hardness may be measured by a variety of methods. For example, Shore hardness may be measured according to ISO 7619-1 , ISO 868 and ASTM D2240 with a portable hardness tester, and ball indentation hardness according to ISO 2039-1 ISO 2039-2 and Rockwell hardness according to ASTM D785 may be measured with laboratory indentors. Some examples of suitable first, softer materials include thermoplastic elastomers such as Styrenic block copolymers (TPE-s), Thermoplastic olefins (TPE-o), Elastomeric alloys (TPE-v or TPV), Thermoplastic polyurethanes (TPU), Thermoplastic copolyester (TPE-E), Thermoplastic polyamides. Some examples of suitable second, harder materials include thermoplastic engineering polymers such as polyesters like polybutylene terephthalate and polyethylene terephthalate or polyamides, as well as their copolymers and blends with other polymers.

In some embodiments, the bristles 22 will contain fillers, such as glass or other inorganic fibers for providing abrasive or strengthened mechanical properties. As discussed later, these fiber fillers may be used to support the creation of fibrous extensions 60 (flagging) on the bristle 22. In specific embodiments the fillers may be in particulate form. However in many embodiments of the present invention, the bristles 22 will substantially lack, preferably be free of, any outwardly protruding particles. In certain embodiments the outer portion 24 made of a first, softer material will contain additives to provide antimicrobial properties to inhibit the growth of bacteria and mold.

In some embodiments, the bristles 22 have a tensile strength at breakpoint of more than about 200, preferably about 100 N/mm ² and/or an elongation at breakpoint of more than about 100%, both as measured analogously to DIN EN ISO 527-1. In some further embodiments, the bristles 22 have a bending strength of at least about 30, specifically about 40, more specifically about 50 mN as measured analogously to DIN EN 53 121. In still further embodiments, the boiling shrinkage of the bristles 22 in less than about 20, preferably about 15 % as measured analogously to DIN 53 866 part 2.

In some embodiments, the outer portion 24 made of a first, softer material will be in the form of a sheath over the inner portion 26 made of a second, harder material in form of a core. In some embodiments the sheath thickness will be between about 0.005 and about 0.15, preferably about 0.01 and about 0.1 , and more preferably about 0.015 and about 0.04 mm. In more specific embodiments, the bristles 22 will have a total maximum diameter of about 2 mil to about 12 mil, alternatively about 0.1 to about 0.4 mm. In alternative specific embodiments, the outer portion 24 will be less than about 25% of the total mass or alternatively the thickness of the bristle 22.

Fig. 4 shows an embodiment in which recesses 40 are located along the length of the bristle 22 and near the tapered end-section 30. The first recess 42 is located closest to the bristle end 50 at a distance of about 0.15 to about 0.4 mm. The bristle 22 has a fibrous extension 60 located within the tapered end-section 30, in particular here at the bristle end 50. In one embodiment (not shown), all of the bristles 22 end in a tapered end-section 30 having at least one fibrous extension 60, and, in another more specific embodiment, some of the bristles 22 have at least two fibrous extensions 60.

The fibrous extensions 60 in the present invention may be generated by conventional flagging means and methods to split bristles 22 one or more times near their tip in order to increase their surface area and capacity for taking up material. The fibrous extensions are also particularly beneficial for some applications involving contact of the bristle with many sensitive nerves of the user, such as on the lips. In other cases, they are very useful in applying liquid compositions, as in the case of nail polish. Such flagging methods for bristles 22 include sanding or grinding or polishing, adhering flocks to the bristle core through thermal or chemical means, electrostatic deposition, cold drawing them to the breaking point, subjecting them to an impact on their surface, for example, by slitting them with sharp metal knife blades mounted on a rotating spindle, or co-extrusion. In a preferred embodiment, the fibrous extensions 60 are generated by means of sanding, polishing, or grinding. Sanding is a preferred method for creating flagging as it is a milder method. Sanding creates flagging or fibrous extensions without splitting the bristle end into sections as with cutting methods. Cutting bristle ends into sections would increase the volume and cause a“ballooning” of the tip area, which would then be counter-productive for the separation properties of the bristle and its brush. In order to support the creation of fibrous extensions 60, the fibers or filaments used for manufacturing the bristles 22 may be filled with reinforcing fibers such as glass or carbon fibers. Typical fibrous extensions 60 will often be in the form of several separate partial cross-sections or fingers, often yielding a fleecy or bulbous structure. The fibrous extensions 60 will typically often have maximum end to end lengths when viewed under a microscope in unloaded form of between about ¼ to about 4x, preferably from about 1/2 to about 3x their average bristle diameter. Alternatively, they will have maximum end to end lengths of between about 1/5 to about 3x, specifically about ¼ to about 2x the taper length of their tapered end-section 30.

“Soft and flexible” in reference to the fibrous extension 60 refers to the ability of the fibrous extension 60 to bend and substantially lay on the surface of the tapered end-section 30 of the bristle 22 when loaded with material. Thus the fibrous extension 60 has substantially no bending recovery strength in comparison to the bristle 22. This ability to bend and lay on the surface may be observed microscopically upon testing of bristle loading with material. Alternative methods of measuring bending recovery are also known from“The Measurement Of The Bending Elastic Recovery Of Filaments”, by J. Skelton, as published in the Journal of the Textile Institute Transactions Vol. 56 , Iss. 8, 1965.

Fig. 6 shows the interaction between a fibrous extension 60 of a bristle 22 embodiment and two lashes 70 showing pay off (a) starting with the first contact of the two lashes 70 with the fibrous extension 60 and then (b) how the lashes 70 move the fibrous extension 60 so that it bends and substantially lays on the surface of the tapered end-section 30 of the bristle 22. Such behavior may be observed under a microscope upon testing the take-up and pay-off of the brush 1 or its bristles 22 with cosmetic or healthcare masses.

Fig. 7 shows the interaction between an orifice 82 of a wiper 80 and the fibrous extensions 60 and the Flexible Region (FR) of the bristles 22. One sees in this figure that the material loading on the fibrous extensions 60 remains substantially unaffected by the wiping action as the fibrous extensions 60 have essentially no bending recovery strength and thus are relatively unaffected by the wiping. The cosmetic and/or healthcare masses in the present invention are not specifically limited and may include mascara, eye shadow, eyeliner, nail lacquer, lip gloss and other lip make-up.

While various embodiments have been set forth for the purpose of illustration, the foregoing descriptions should not be deemed to be a limitation on the scope herein. Accordingly, various modifications, adaptations, and alternatives can occur to one skilled in the art without departing from the spirit and scope herein.

Reference Numbers

1 cosmetic and healthcare brush

10 core section

12 wire segment

20 bristle section

22 bristle

24 outer portion

26 inner portion

28 cross-section

30 tapered end-section

35 taper length

40 recess

40’ partial recess

42 first recess

45 separation distance

50 bristle end

60 fibrous extension

70 eyelash

80 wiper

82 wiper orifice

Reference Signs

AR = Active Region

BR = Base Region

C = Circular

CFR = Central Fixing Region DB = Dumbbell

FR = Free Region