Applicator Having a Microstructured Surface

Abstract

The invention relates to a bristle carrier and bristles (1) formed thereon, the surface of the bristles (1) being microstructured at least in segments, in that a plurality of grains (2, 3) protrude haphazardly from the bristle core (4) in the region of the microstructured surface and are connected to the bristle core (4) only along less than 40%, preferably less than 35% of the outer surface thereof, and comprise an average diameter (M1, M2) of less than or equal to 125 m, preferably less than or equal to 90 m.

Claims

1. An applicator having a bristle carrier and bristles (1) formed thereon, characterized in that the surface of the bristles (1) is microstructured at least in segments, in that a plurality of grains (2, 3) protrude haphazardly from the bristle core (4) in the region of the microstructured surface and are connected to the bristle core (4) only along less than 40%, preferably less than 35% of the outer surface thereof, and comprising an average diameter (M1, M2) of less than or equal to 125 m, preferably less than or equal to 90 m.

2. An applicator having a cosmetic application surface, characterized in that the cosmetic application surface is microstructured at least in segments, in that a plurality of grains (2, 3) protrude haphazardly from the cosmetic application surface in the region of the microstructured surface and are connected to the cosmetic application surface only along less than 40%, preferably less than 35% of the outer surface thereof, and comprising an average diameter (M1, M2) of less than or equal to 125 m, preferably less than or equal to 90 m.

3. The applicator according to claim 1 or 2, characterized in that the grains (2, 3) comprise first grains (2) or are made entirely of first grains (2) having an average diameter (M1) of at least 30 m and preferably at least 40 m.

4. The applicator according to any one of the claims 1 through 3, characterized in that a plurality of second grains (3) are haphazardly distributed between or on the first grains (2) and protrude from the bristle core (4) according to claim 1 and/or in a corresponding manner from the first grains (2), and the average diameter (M2) thereof is less than or equal to 30 m, preferably less than or equal to 25 m.

5. The applicator according to any one of the claims 1 through 4, characterized in that the bristle surface comprises in any case an area of 1 mm.sup.2 at which at least 5, preferably at least 8 first grains (2) protrude as described above.

6. The applicator according to any one of the claims 1 through 5, characterized in that an undercut (5) is present at least locally, preferably of at least 70% all around, between the point at which a first grain (2) is connected to the bristle core (4) along the circumference thereof and the maximum circumference (Max) of the first grain (2) protruding outward.

7. The applicator according to claim 6, characterized in that on an area of 1 mm.sup.2, a plurality of grains (2) having an undercut and directly adjacent to each other are present, and the grains (2) do not touch each other, but rather the least distance (KA) between said grains occurs above the region (B) at which said grains are bonded to the bristle coresubstantially as seen in the radial direction (R)from which point the distance between said grains increases until the region (B) at which said grains are bonded to the bristle core (4).

8. The applicator according to any one of the preceding claims, characterized in that at least 30% of the free surface of the microstructured bristle segment is present in the region of a radial undercut (5).

9. The applicator according to any one of the preceding claims, characterized in that the bristle carrier comprises a free surface in a region without bristles, between surrounding bristles, and is microstructured at least in segments, in that a plurality of first grains protrude from the bristle core in the region of the microstructured surface and are connected to the bristle core along less than 40%, preferably less than 30%, of the outer surface thereof, and comprise an average diameter of less than or equal to 125 m, preferably less than or equal to 90 m.

10. The applicator according to any one of the preceding claims, characterized in that the applicator core or bristle carrier is an injection-molded plastic part or a metal part without bristles or having bristle stubs, having bristles applied thereto in layers.

11. The applicator according to claim 9, characterized in that part of the bristles are injection-molded bristles between which additional bristles have been installed subsequently by means of a primary layer forming process.

12. An applicator, preferably according to any one of the preceding claims, characterized in that the carrying proportion of the edge layer of the applicator is 50% measured down to a depth of 2/10 mm and preferably to a depth of 4/10 mm.

13. A method for producing an applicator according to claim 10, characterized in that an applicator core or bristle carrier is produced as an injection-molded part and subjected to a treatment and preferably a corona treatment prior to applying the bristles in layers, said treatment increasing the surface tension of said applicator or bristle carrier and preferably set up for increasing the polar portion of the surface tension.

14. The method according to claim 10, characterized in that the surface tension of the material of said applicator core or bristle carrier is adjusted to be greater than the surface tension of the material being applied.

Description

LIST OF FIGURES

[0041] FIG. 1 shows an embodiment example of a bristle microstructured according to the invention in the region of the tip thereof, where a substantial part of the tip has broken off, depicted by the view of the hatched bristle core.

[0042] FIG. 2 shows a detail magnification from the left flank of the microstructured bristle tip according to FIG. 1.

[0043] FIG. 3 illustrates the substantial dimensions of a bristle according to the invention and the lateral deflectability thereof.

[0044] FIG. 4 illustrates the application of the invention to a lip applicator having no bristles whatsoever.

[0045] FIG. 5 shows the application of the invention to another lip applicator also having no bristles whatsoever but also having a macroscopic structure, wherein a partial section view having the front part cut away is depicted here.

DESCRIPTION OF EMBODIMENT EXAMPLES

First Embodiment Example

[0046] FIG. 1 shows the top part of a bristle made of plastic for forming the edging of a bristle applicator according to the invention.

[0047] The length LAE of a bristle according to the invention is typically between 3 mm and 10 mm. The maximum bristle diameter DB of a bristle according to the invention is typically between 0.01 mm and 0.05 mm.

[0048] The bristle according to the invention is preferably flexible, that is, able to be deflected laterally. The flexibility is typically great enough that the tip of the bristle can be reversibly elastically laterally deflected by the forces arising during application by at least four times, preferably six times, the amount BT of the maximum bristle diameter (measured above any fillet where the bristle transitions into the bristle carrier), as shown in FIG. 3.

[0049] It is particularly advantageous if the bristle tapers down from the base to the tip thereof, preferably at an average taper angle AP of 0.2 to 10.

[0050] Applicators according to the invention typically have between 75 and 750 bristles of the type described here. It is further noted that the plastic of the bristles need not be identical to the plastic of the bristle carrier, even if the bristles and bristle carrier transition into each other as a single part. It can further be advantageous to produce the bristle from different plastics along different regions. It has been found to be advantageous, for example, to produce the bristles from a particularly elastic plastic in the base region thereof, in order to produce a type of joint at said point about which the bristle can be pivoted back and forth.

[0051] For the bristle shown in FIG. 1, only the region of the bristle tip has the microstructuring according to the invention. Further isolated regions of the bristle could additionally have such microstructuring. For example, the one or more rings spaced apart from each other as described above and enclosing the circumference of the bristle could also be thus equipped. For some other applications, it is particularly advantageous to provide the entire bristle with the microstructuring according to the invention.

Second Embodiment Example

[0052] A second embodiment example of the invention is shown in the top half of FIG. 4, and a third embodiment example in the bottom half of FIG. 4. Depicted is a lip applicator. The blank of said lip applicator is preferably produced as an injection-molded part. The lip applicator has then been equipped with a microstructured surface according to the invention in segments in the manner described above.

[0053] For the case of the second embodiment example, the end face 6 of the lip applicator, intended for taking up from the store a certain quantity of the cosmetic to be applied and for applying the same to the lips, has been equipped according to the invention.

[0054] As can be seen here, first regions 7 microstructured according to the invention are provided at the edge of the end face 6. Said regions 7 are preferably microstructured such that the cosmetic to be applied adheres particularly well thereto. In this manner, smudging can be prevented or delayed, as it would otherwise be likely to occur that a certain amount of the viscous cosmetic received adhesively by the end face at first would slip off and then drip over the edge of the end face.

[0055] The adhesion can be further improved if second (typically 5 to 25 in count) microstructured regions 8 are also present. Said further microstructured regions 8 are preferably implemented as islands separate from each other, each of which ideally individually comprises a circular, oval, elliptical, or plum-shaped surface extent.

[0056] The microstructured surface in the present embodiment example preferably takes up only a minority of the surface intended as the application surface (typically the end face).

[0057] The third embodiment example is depicted in the bottom half of FIG. 4.

[0058] For the case of the third embodiment example, the end face 6 of the lip applicator, intended for taking up from the store a certain quantity of the cosmetic to be applied and for applying the same to the lips, has also been equipped according to the invention. For this purpose, microstructured regions 9 are present, here having the shape of concentric or equidistantly spaced rings. Conventional regions 10 can also be provided in the shape of rings between the microstructured regions.

[0059] The present arrangement can also have an extremely positive effect on the mass storage and mass discharge behavior. For a corresponding design of the surface structure according to the invention, the microstructured regions 9 can take up an increased quantity of the cosmetic from the store and transport the same to the skin area to be treated. During application, part of the mass stored by the microstructured regions is then first forced into the conventional regions and then particularly quickly transferred therefrom to the skin area to be treated.

[0060] It is noted that the microstructured surface according to the invention and a macroscopic surface structure can overlap spatially and can preferably also reinforce each other in effect. This is evident from the fourth embodiment example, as illustrated in FIG. 5.

[0061] Macroscopically raised regions 11 are implemented here on the lip applicator. The structures here protrude in any case by at least 0.8 mm (FIG. 5, dimension A) at least in a direction opposite the immediate surrounding area thereof (FIG. 5, dimension W) spaced apart by a maximum of 3 mm on both sides along said direction. Because the raised region of FIG. 5 is additionally provided with the microstructured surface according to the invention, the material storage capacity of the valleys 12 is significantly increased.

[0062] Depending on the rheology of the cosmetic material to be applied, it can be sensible to alternatively equip only the valleys 12 with the microstructured surface according to the invention, or to additionally equip the valleys 12 with the microstructured surface.

Details of the Microstructuring Used for the Embodiment Examples

[0063] The details of the microstructuring according to the invention (for a bristle in the example) can be seen well in FIG. 2.

[0064] As is evident, the bristle has a bristle core 4. The bristle core 4 can have a homogenous microstructure or a grained microstructure. A homogenous microstructure can also mean that local air inclusions or local gaps are present (not shown in the drawing), as long as said features do not reduce the strength and elasticity of the bristle to the extent that the bristle no longer exhibits the flexibility indicated above.

[0065] The embodiments below apply analogously to an applicator without bristles. Said applicator can also comprise a corresponding applicator core having a homogenous microstructure or a grainy microstructure. A homogenous microstructure, in this case, can also mean that local air inclusions or local gaps are present (not shown in the drawing) as long as said inclusions or gaps do not substantially reduce the strength and elasticity of the bristle.

[0066] The following applies analogously for both embodiment examples:

[0067] As is evident, a plurality of grains 2, 3 protrude from the surface of the bristle in the microstructured region. As can be seen well in FIG. 2, said grains have a free outer surface, that is, the outermost local limit of the outer surface forming the bristle here. The shortest theoretical intersecting surface area by means of which each grain could theoretically be cut off from the bristle core 4, is less than 40% of the free outer surface of each grain for the grains 2, 3 essential to the invention.

[0068] The grains have a certain size. How this size is determined can also be seen well in FIG. 2. A theoretical sphere is formed in which the grain to be measured is inscribed. The radius of the smallest possible sphere in which the grain (as measured optically) can be inscribed is the average diameter M of the grain. Said average diameter M is 125 m for the grains according to the invention.

[0069] Differentiation is thereby preferably made between larger first grains 2 and smaller second grains 3. Said two types of grains can also be seen well in FIG. 2. The larger grains 2 are characterized in that said grains have an average diameter M of at least 30 m.

[0070] In contrast, the preferably additionally present, smaller grains 2 are characterized in that said grains have an average diameter M of <30 m and preferably even <25 m.

[0071] As can be easily understood from FIG. 2, the microstructuring according to the invention forms a wildly rugged surface having many undercuts sized so as to be filled in by the cosmetic material. In this manner, many protrusions and recesses result, at which the cosmetic material can adhere. Therefore, even if the cosmetic material is set up so as to not easily coat a smooth surface smoothly, said surface can be well loaded with the cosmetic material.

[0072] The retaining effect can be further increased if the production method is set up so that grains occur immediately adjacent to each other but do not make contact.

[0073] Said grains are then advantageously bonded to the bristle core such that the spacing again increases from the point at which said grains are spaced apart by the least distance KA from each other to the region B where said grains are bonded to the bristle core.

[0074] In this manner, opposing undercuts are formed and exhibit particularly a good retention effect.

[0075] Such an arrangement is shown in FIG. 2 just above the center of the figure and is marked with reference numbers.

[0076] Wherever an applicator core or bristle carrier is produced as a prefabricated part, particularly as an injection-molded part, in order to apply a structured surface or bristles thereto in layers it is sensible to subject the surface of said blank to a treatment for preparing the same in order to ensure good adhesion of the material to be applied. This applies not least when said blank is made of polyethylene, polypropylene, and polyester.

[0077] Suitable treating methods here include corona treatment and possibly alternatively fluoridation or flame or plasma treatment. The objective of said methods is to increase the polarity of the surfaces, whereby the coatability and chemical affinity are increased significantly.

[0078] Corona treatment is typically performed in line at the end of the production process for the blank. The blank, such as a cylindrical bristle carrier without bristles, is thereby subjected to a high-voltage electrical discharge. Said discharge occurs between a grounded, polished plate or roller made of steel or aluminum and an insulated electrode nearby.

[0079] Depending on the field of application, the use of an insulated roller and non-insulated electrodes is also possible.

[0080] The bristle carrier thereby rotates about the electrode. The electrode is supplied by a high-frequency generator at an alternating voltage of 10 to 20 kV and a frequency between 10 and 60 kHz.

REFERENCE LIST

[0081] 1 Bristle [0082] 2 First grain [0083] 3 Second grain [0084] 4 Bristle core [0085] 5 Undercut [0086] 6 End face of the lip applicator (application surface) [0087] 7 (First) region having a microstructured surface [0088] 8 (Second) region having a microstructured surface [0089] 9 (Additional) region having a microstructured surface [0090] 10 Conventional region [0091] 11 (Macroscopically) raised region [0092] 12 Valley [0093] R Radial direction [0094] B Region in which a grain is bonded to the bristle core 4 [0095] KA Least distance between 2 directly adjacent grains [0096] L Longitudinal axis of a bristle [0097] M Average diameter of a grain [0098] Max Maximum circumference of a grain [0099] LAE Bristle length [0100] DB Bristle diameter, max [0101] BT Amount by which a bristle can be reversibly deflected [0102] AB Average cone angle/taper angle of a bristle

[0103] A Dimension by which the raised region is raised W Dimension of distance between the raised region and a non-raised region (valley)