EP3516988A1

EP3516988A1 - An improved bristle for brushes

Info

Publication number: EP3516988A1
Application number: EP18154207.7A
Authority: EP
Inventors: Wolfgang KAMM; Huong BISTER
Original assignee: Geka GmbH
Current assignee: Geka GmbH
Priority date: 2018-01-30
Filing date: 2018-01-30
Publication date: 2019-07-31
Also published as: WO2019149760A1; EP3745912B1; EP3745912A1

Abstract

A bristle 22 for a cosmetic and/or healthcare brush 1 is disclosed comprising: (a) an outer portion 24 made of a first, softer material and an inner portion 26 made of a second, harder material, and (b) a tapered end-section 30, wherein the tapered end-section 30 has at least one fibrous extension 60 located within the tapered end-section 30. The present invention also relates to a brush 1 or a dispenser comprising said bristle.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an improved bristle for a brush, particularly a cosmetic and/or healthcare brush, as well as a brush and dispenser comprising the bristle.
In the field of brushes, natural fiber brushes have a long history and tradition, and natural fibers are often preferred for premium products and applications due to their favorable properties. For example, natural fibers, such as goat, pony, badger, duck, and pig hairs all have a naturally tapered hair end with flagging in the end portion. Cut natural hairs however have at least one end with a straight cut lacking these favorable properties. In automated brush production processes, it is then necessary to accurately and in a controlled-manner to produce the brush such that the natural tapered tips of the hairs having flagging are facing outwards and not towards the core of the brush.
In addition, it is difficult to obtain natural hair of a certain specific quality and color, as these properties vary considerably from animal to animal. In addition, natural hair is a limited resource and difficult to store. Furthermore although a natural hair may be quite long, only the end of it has the desirable characteristics of the tapered end section and flagging. Thus much of the natural hair length lacks this desirable property. For these reasons, it would be desirable to develop synthetic filaments and bristles having the desirable properties of the tapered end section together with flagging, as in these premium natural hairs. In particular, it would be desired to have synthetic filaments and bristles that are readily produced with the tapered end sections and flagging on both ends of the filament or bristle, e.g. for application in Twisted Wire Brushes (TWB) or staple brushes.
In the cosmetic and healthcare field, particularly in the application of formulations to hair, such as mascara, it is also 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 the wedge-shaped tips of its bristles. Nonetheless, this brush and its bristles do not provide high volume because a standard wiping action with this brush wipes off too much of the standard formulation from the bristles in this action.
As another example, WO2016/016436 A1 discloses a TWB also having wedge-shaped bristle tips combined with an increased tip surface roughness obtained from plastic filaments filled with fine clay or silica particles having a particle size of between 0.01 µm to 100 µm (added during extrusion according to the method of US 6,311,359 B1 ). In the process of WO'436 A1, the wedge-shaped bristle tips are ground using a grinding disc to provide surface roughness of the wedge-shaped bristle tips resulting from the exposed outwardly protruding and/or even depressions resulting from the subsequent loss of some particles due to grinding away of surface plastic on the tips. This process then results in wedge-shaped tips having an enhanced fine surface roughness (Rz) of between 0.2 µm and 6.3 µm. Although the capacity of the bristles to take up mascara is improved due to the increased surface roughness of wedge-shaped tips, however the increase in capacity is somewhat limited. This is because the increase in capacity of the bristle is due only to the limited increase in surface area of the bristle end caused by the wedge shape and the fine surface structure resulting from protruding fine particles or depressions resulting from their loss. In addition, this method of increasing capacity is somewhat complex and inefficient and difficult to control well as the entire bristle fiber must be filled with particles during extrusion although the increase in surface area and capacity is primarily limited to the ground wedge-shaped tips. Also the grinding must be done quite precisely to obtain the desired protrusion of particles and/or depressions. Although filling bristles with particles may bring other benefits, such as improved mechanical properties, the method of WO0'436 A1 is obviously limited in its application to only filled bristles.
Therefore it is desirable to provide an improved bristle so as to provide brushes, particularly TWB brushes, with both high separation and volume in one single TWB brush, especially for cosmetic and healthcare applications, particularly for hair or skin, more specifically eyelashes, and hair. Furthermore, it would be desirable to have a bristle that is embodied for providing favourable tip properties similar to those of natural hair fibers, preferably improved separation and pick-up and pay-off properties. In addition, it would be desirable to have an improved bristle that may be made from both filled and non-filled fibers and with a well-controlled and easily obtainable high capacity.

SUMMARY OF THE INVENTION

Starting from this state of the art, it is an object of the invention to provide an improved bristle for a brush providing both high separation and volume, in particular a bristle that is embodied for providing favourable tip properties similar to those of natural hair fibers, preferably improved separation and pick-up and pay-off properties.
According to the invention, these objects are achieved by a bristle embodied for providing favourable tip properties similar to those of natural hair fibers, preferably improved separation and pick-up and pay-off properties, comprising: (a) an outer portion made of a first, softer material and an inner portion made of a second, harder material (b) a tapered end-section, wherein (c) the tapered end-section has at least one, preferably more than one, fibrous extension located within the tapered end-section, preferably at the bristle end.
The bristles of the present invention have the favourable properties of natural hair, such as goat hair, but they can readily be made by machine to any desired length, even double-ended (both free ends having tapered end-sections), for example, making use of stapling.
The inventors have surprisingly found that said bristles provides both favourable separation and volume properties for brushes comprising them. 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 the bristle 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 bristle of the present invention, the tapered end-section has 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 some embodiments of the present invention, the tapered end-section has 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 bristle the tapered end-section ends in a chisel-like taper consisting of either a single (chisel-like configuration) or a double angle (roof-like configuration) cut tangentially or obliquely (to the axis of the bristle core. It is to be understood that the tapered end-section and wedge shapes need not 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 α (relative to the longitudinal axis of the bristle) of the bristles may vary from 80° to approximately 89° in one embodiment. Smaller wedge angles α between 5° and 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. Such machine-manufactured bristles have advantages over natural hairs in that they may be readily made to any desired length, and even made double-ended (having two tapered end-sections), for example, taking advantage of stapling methods.
Selected embodiments of the present invention have advantages over both natural hairs as well as synthetic bristles of the prior art as the present bristles may be made to have any desired length and the bristles may be made with a tapered end-section and flagging (fibrous extension) at both ends for use with staple-set brushes, for example. In contrast, natural hairs will always have flagging only on one side, and when they are cut to length the residual section has no flagging on either side. The same is true of synthetic bristles having flagging that are cut to length. However in the present invention, the bristles may be cut to length and the provided with a tapered end-section and flagging at both ends using the disclosed methods, such as grinding. Methods to create bristles with flagging on both ends are also known in the art.
In other specific embodiments of the bristle, 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 of the bristle, 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.
In one embodiment of the bristle of the present invention, the cross-section of the bristle varies in shape lengthwise along the bristle, which then provides for (indented) recesses or other similar reservoirs for materials such as cosmetic or healthcare masses along the length of the bristle, particularly in the active region near the tapered tip. The cosmetic and healthcare mass residing in these recesses or reservoirs will not be wiped off during the standard wiping action.
In another embodiment of the bristle of the present invention, at least a portion of the bristle has 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 of the present invention, at least 50, 75, 90% or essentially all of the bristles have recesses. These recesses advantageously provide the just-discussed reservoirs for the cosmetic and healthcare mass or other material to reside in. The filament of the bristle is 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 or square circumferences and often with a funnel-like narrowing profile towards the interior or core of the bristle. In other embodiments, the recesses will have average diameters on the bristle face or surface of more than 100, particularly 150, more particularly 200 µm. Therefore in preferred embodiments the recesses are distributed non-randomly and substantially regularly with substantially constant spacing between recesses, preferably of ± 20, more preferably 10, most preferably 5%. In some more specific embodiments, the maximum distance between recesses is between about 0.2 to about 2.0 mm.
In certain preferred embodiments 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. 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 certain other preferred embodiments, there is 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 bristle, the first recess located closest to the bristle end along the bristle is located at a distance of between about 0.1 mm to about 1.0 mm from the bristle end, preferably about 0.2 to about 0.8, more preferably about 0.3 to about 0.6, 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 µm.
In certain embodiments of the bristle, the 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 as in the present invention.
One aspect of the present invention is a brush, preferably a cosmetic or healthcare brush, more preferably a cosmetic or healthcare twisted wire brush (TWB), comprising one or more, preferably a majority, of bristles of any of the embodiments of the present invention. Another aspect of the present invention is a dispenser, preferably a cosmetic or healthcare dispenser, comprising said brush, preferably containing a cosmetic and/or healthcare mass. Such a brush or 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 bristle claim may be combined with the subject matter of one or more other bristle claims or the subject matter of one or more brush claims or the subject matter of a mixture of one or more bristle claims and brush claims. By analogy, the subject matter of any one brush claim may be combined with the subject matter of one or more other bristle or brush claims or the subject matter of one or more bristle claims or the subject matter of a mixture of one or more bristle or bristle claims and brush claims. One skilled in the art will understand that such combinations may also pertain to dispenser claims or their combinations with bristle or 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 bristle embodiments may be combined with the subject matter of one or more of the other above-mentioned brush or 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 bristles according to the invention having a tapered end-section and fibrous extensions.
Fig. 2: (a) and (b) shows the individual regions of a bristle.
Fig. 3: shows a schematic view of the cross-sections of 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 with a first recess located near the tapered end, and a fibrous extension at the bristle end.
Fig. 5: 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. 6: 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 bristle due to the interaction of the orifice primarily with the stiffer bristle rather than with the floppy fibrous extension.
Fig. 7: shows a schematic view of an embodiment of a brush according to the invention.

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 similar to that of the goat hair cross-sectional profile as described in section 4.1.3.9 Ziegenhaar on p. 143 in the handbook, "Bürsten und Pinsel" by Ernst Bock, published in 1983 by the Fachbuch Verband der Deutschen Pinsel- und Bürstenhersteller 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/library/textile/.

A "recess" in the present invention 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 that method filaments are extruded with fine clay or silica additives having a particle size of from 0.01 to 100 µm 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 µm diameter particles.
A "partial recess" is a recess that is only partially present on the bristles as a portion of the recess has been cut away in the process of 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 one embodiment of a bristle 22 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 cross-section 28 of the bristle 22 varies in shape lengthwise along the bristle 22, at least a portion of the bristle 22 has recesses 40, and the bristle 22 has a tapered end-section 30 having at least one fibrous extension 60 located within the tapered end-section 30.
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, 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 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. At least some of the bristles of the 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 (flagging) on the bristle. 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/mm² 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. Fig. 4B shows an embodiment in which all of the bristles 22 end in a tapered end-section 30 having at least one fibrous extension 60. Some of the bristles 22 are shown to 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 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 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, grinding or polishing. 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, 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. 5 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. 6 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.
Fig. 7 shows an embodiment of a cosmetic or healthcare TWB 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 in this embodiment.
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 comprise (a) an outer portion 24 made of a first, softer material and an inner portion 26 made of a second, harder material, and (b) a tapered end-section 30, wherein (c) the tapered end-section 30 has at least one, preferably more than one, fibrous extension 60 located within the tapered end-section 30, preferred at the bristle end 50.
The cosmetic brush 1 is not specifically limited and may be a foundation brush, concealer brush, kabuki brush, stippling brush, angled blush brush, powder brush, angled brush, contour brush, highlight fan brush, blending brush, eye liner brush, angled eyeliner brush, eyeshadow brush, nail brush, nail polish brush, nail lacquer brush, bronzer brush, shaving brush, lip brush, mascara brush, all-over eye shadow brush, lash/brow comb/brush, smudger brush, fan brush, or blush brush. The healthcare brush 1 is also not specifically limited and it may be for oral health care, for example, a toothbrush or interdental brush, or for mucus membrane or bleaching treatment; or for dermal care, such as prescription medicated skin care dermatology, OTC skin care, cosmetic skin care or cosmeceuticals; or for eye care, such as application on the inside of the eye (e.g. eye drops and ointment application, antibiotics or antimicrobials), or external eye applications (e.g. infections, sty, lashes / brow treatments); or for hair or scalp treatments; a nail, nail-lacquer, or nail-polish brush; or for ear, nasal, foot, rectal or vaginal care of treatment; or for diagnostic treatments or medical sampling; or for diagnostic, grooming, dermal, oral, eye or other healthcare of animals.
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 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, toothpaste, bleach, prescription medication, OTC medication, cosmeceuticals, eye drops, eye ointment, antibiotics, antimicrobials, or nail polish.
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
TWB = Twisted Wire Brush

Claims

A bristle (22) for a cosmetic and/or healthcare brush comprising:
(a) an outer portion (24) made of a first, softer material and an inner portion (26) made of a second, harder material, and

(b) a tapered end-section (30), characterized in that

(c) the tapered end-section (30) has at least one, preferably more than one, fibrous extension (60) located within the tapered end-section (30), preferably at the bristle end (50).
The bristle (22) of claim 1, wherein the tapered end-section (30) has a taper length (35) of from about 0.2 mm to about 1 mm and preferably ends in a chisel-like taper consisting of either a single or a double angle cut tangentially to the axis of the bristle core.
The bristle (22) of either one of claims 1 or 2, wherein the fibrous extension (60) comprises either the first, softer material or the second, harder material, preferably the first, softer material, preferably either a mass majority of the first, softer material and a mass minority of the second, harder material OR a mass majority of the second, harder material and a mass minority of the first, softer material.
The bristle (22) of any one of claims 1 to 3, wherein the fibrous extension (60) is embodied so as to pick up a portion of a cosmetic and healthcare formulation when it 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 (60) after subsequent wiping of the bristle (22).
The bristle (22) of any one of claims 1 to 4, wherein the fibrous extension (60) is selected to be suitably soft and flexible so that it may bend and substantially lay on the surface of the tapered end-section (30) of the bristle (22), preferably while retaining the residue of the picked up portion of the cosmetic and healthcare formulation on the fibrous extension (60) after subsequent wiping of the bristle (22).
The bristle (22) of any one of claims 1 to 5, wherein the cross-section (28) of the bristle (22) varies in shape lengthwise along the bristle (22).
The bristle of any one of claims 1 to 6, wherein at least a portion of the bristle (22) has recesses (40), wherein preferably the recesses (40) are distributed over the entire length of the bristle (22), preferably uniformly distributed over the entire length.
The bristle (22) of claim 7, wherein at least a portion of the recesses (40) are located along the bristle length within a distance of 3 mm, preferably 2 mm, from the far end of the tapered end-section (30) of the bristle (22).
The bristle (22) of either claim 7 or 8, wherein a minimum separation distance between the recesses (40), measured from starting point to starting point of adjacent recesses (40), along their bristle (22) 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 mm.
The bristle (22) of any one of claims 7 to 9, wherein the first recess (42) located closest to the bristle end (50) along a bristle (22) is located at a distance of between about 0.1 mm to about 1.0 mm from the bristle end (50), preferably about 0.2 to about 0.8, more preferably about 0.3 to about 0.6 mm, even more preferably within the tapered end-section (30), most preferably the first recess (42) is a partial recess (40') within the tapered end-section (30).
The bristle (22) of any one of any one of claims 7 to 10, wherein the bristle cross-section (28) is non-cylindrical within and adjacent to the region of the recess (40).
The bristle (22) of any one of claims 7 to 11, wherein the recesses (40) on a bristle (22) are located substantially opposed to one another, preferably so as to confer the bristle (22) with a substantially hour glass or dumbbell (DB) shaped cross-section (28) in the region of the bristle (22) containing said recesses (40), more preferably so as to confer the bristle (22) with a cross-sectional profile similar to that of goat hair.
A brush (1), preferably a cosmetic or healthcare brush, more preferably a cosmetic or healthcare twisted wire brush (TWB), comprising one or more, preferably a majority, of bristles (22) of any one of claims 1 to 12.
A dispenser, preferably a cosmetic or healthcare dispenser, comprising the brush (1) of claim 13, preferably containing a cosmetic and/or healthcare mass.