EP0574572B1 - Brush with reduced number of bristles for the application of mascara to the eyelashes - Google Patents

Abstract

The invention relates to a brush for the application of mascara to the eyelashes, comprised of a central core formed by a twisted metal wire (1) whose twists catch between each other the bristles (2) of the brush, said bristles (2) being arranged substantially regularly between said twists, the invention being characterized in that the bristles (2) have a substantially circular solid straight section whose diameter is comprised between 0.12 and 0.25 mm, the number of bristles (2) per turn being comprised between 5 and 9, said bristles forming substantially a single helical layer wherein each bristle has a substantially radial orientation, the angle between two adjacent bristels of the layer being substantially constant with an approximate tolerance of 20 %.

Description

The present invention relates to a brush intended for making up the eyelashes by means of an eyelash enhancing product also called mascara.

The usual brushes of this type generally comprise relatively long bristles arranged in a helical sheet around a core constituted by a twisted wire. The importance of the stacking of the brush is measured by the number of bristles constituting a turn of the helical sheet of angular opening equal to 360 °.

In the prior art, relatively flexible bristles were used so as to give the brush an overall characteristic of appropriate flexibility; since it is a question of making up a support as delicate as eyelashes, the maximum diameter of the hairs was generally of the order of 0.08 mm; the bristles used were generally made of polyamide. In this case, since the bristles of small diameter indicated above have by themselves very low rigidity, it was ensured that a sufficient quantity of mascara was removed and that the eyelashes were brushed correctly at the time of application. adopting a quantity of bristles per turn always greater than 50 so that the helical sheet is thick enough to obtain the desired result. The helical ply of bristles generally had a pitch of about 2 mm and in the thickness of the ply, the bristles were substantially parallel.

However, it appeared that such brushes did not ensure good use of the makeup product on the eyelashes during use. Indeed, in practice, the mascara is often placed on the eyelashes in packs, without any homogeneity, which requires the user to perform repeated brushing until obtaining an almost regular coating of the eyelashes. This drawback comes, firstly, from the fact that these brushes have a large number of bristles tight against each other in the helical sheet so that at the time of application, the eyelashes, the diameter of which is generally between 0 , 08 and 0.12 mm cannot pass through the pile of hairs and can only pass through the intervals between successive turns of the helical layer of bristles. The eyelashes therefore cannot be separated from each other at the time of application, as would be desirable. However, said drawback also comes, secondly, from the fact that at the moment when such a brush of the state of the art picks up the mascara, the latter is poorly distributed over the brush. In fact, a mascara applicator generally comprises a mascara reservoir and a removable cap, which is intended to close the reservoir and which constitutes a handle making it possible to manipulate a makeup brush carried by the end of a rod integral with said cap. In the tank closed position, the rod and the brush, which is associated with it, plunge into the tank; when the rod is removed from the reservoir, a certain amount of mascara is taken from the brush which can then be applied to the eyelashes. The brush enters the interior of the reservoir through a substantially circular orifice bordered by a flexible lip, the role of which is to exert a wringing action on the bristles of the brush in order to remove the excess product of makeup removed by the brush inside the tank. The diameter of this circular orifice is less than the diameter of the brush measured at the top of the bristles so that the flexible lip, which borders the orifice, can exert its wiping action during the extraction of the brush from the reservoir. The bristles of the brush, being relatively flexible and being arranged with a relatively high density in the helical sheet of bristles, lie in the direction of the core at the time of the passage of the sheet through the wiping lip and, in this deformation, they go so far as to cause the "hair" of the hairs of the adjacent coil, where it follows that the makeup product tends to accumulate in the region of the brush situated just around the core. Under these conditions, at the time of application, the user can hardly obtain, in a single pass of the brush, a perfectly regular and homogeneous coating of the eyelashes with the makeup product, the latter having in effect to gradually migrate towards the ends of the hairs initially lightly loaded with product; such migration takes place incidentally randomly. This results in heterogeneous and generally light makeup.

In French patent 2 607 373, which represents the preamble of claim 1, an improved makeup brush has already been proposed making it possible to remedy the aforementioned drawbacks. It has, in fact, been proposed to use bristles of larger diameter and to ensure that these bristles are much more spaced from each other by using a small number of bristles per turn. The brush thus proposed therefore consists of more sparse and harder bristles; it is harder to the touch but does not give an impression of hardness during makeup. The reduction in the number of bristles per turn leads to the possibility for the hairs of the helical sheet situated substantially in the same radial plane of the brush to take randomly, from the zone where they are clamped between the turns, wire which constitutes the core, an angular deviation from the mean helical surface of the helical sheet of bristles; in other words, the edge of the helical layer of bristles becomes wider the smaller the number of bristles per turn. It was found that it was thus possible to obtain brushes for which the helical sheet became barely perceptible, the bristles of a turn of the helical sheet being able to come in the vicinity of the bristles of the adjacent turn of the same helical sheet because of the random angular deviation taken by the bristles in their clamping zone. This particular result was obtained when the bristles have a diameter of between 0.10 and 0.25 mm and the number of bristles per turn is between 10 and 40. It has been found that these improved brushes improve the uniformity of loading in make-up product for the bristles of the brush, from their base to their tip, and also improved the combing of the eyelashes during makeup, due, on the one hand, to the greater firmness of the bristles, of which the diameter was increased, and, on the other hand, their spatial spacing due to the disappearance of the whorl effect.

According to this invention, it was recognized that the stacking of the brush could not be reduced below 10 bristles per turn due to the fact that the "hedgehog" constituted by such a brush would have was too little supplied to allow satisfactory makeup, the eyelashes can then pass through the brush without practically touching a hair loaded with product. This lower limit of the stacking of a brush was, moreover, commonly accepted due to the fact that the skilled person thought that the reduction of the stacking of a brush of the type defined above always resulted in the disappearance the turn effect and the appearance of a "hedgehog" type brush due to a random angular deviation of the bristles relative to the mean helical surface of the ply of bristles; moreover, it appeared that this effect was increasing when the number of hairs per turn decreased for a given hair diameter.

It has now been found that, contrary to what the skilled person was entitled to expect, it occurs, when the number of bristles per turn of a brush of this type is reduced to below 10, a A completely unexpected new phenomenon. Indeed, it has been found, according to the invention, that for bristles having a diameter between 0.12 and 0.25 mm and with a core wire having a diameter between 0.2 and 0.9 mm , the turn effect reappeared when the number of bristles per turn is between 5 and 9. But in such a case, unlike the brushes of the prior art in which the helical layer of bristles has in its thickness a plurality of bristles, the helical sheet produced is a monolayer of bristles each arranged substantially radially and defining a regular helical surface. In such a monolayer sheet, it has been found that using the conventional industrial method of manufacturing brushes of this type, two adjacent bristles of the helical surface formed between them an angle which varied little, in particular by less than 20%, one hair to another from the surface.

This unexpected phenomenon is particularly advantageous when choosing a number of turns per unit of brush length and an external diameter of the brush such that at the periphery of the brush, the ends of the brush bristles are practically all equidistant from each other. others with a small error percentage. It can of course be provided for this equidistance of the ends of the bristles to be obtained only for an area of the brush, either that the brush comprises at least one conical zone, or that the brush is cut by milling in a zone of its peripheral surface lying substantially between two radial planes; in other words, the cross section of the peripheral surface of such a brush can have any shape.

It is recalled that the conventional industrial manufacturing process of mascara brushes of this type consists, in a first step, in folding, with a hairpin, an iron wire; in a second step, to engage between the two branches of the hairpin a series of tufts of bristles which are brought into position by means of a comb whose edge is formed of successive slots, the bristles of the brush being arranged in said slots perpendicular to the mean plane of the comb; in a third step, to grasp the two ends of the hairpin thus loaded with tufts of hair and to cause a relative rotation of the ends so as to form the turns of the wire which constitutes the core of the brush. In this relative rotation, the bristles, distributed in identical tufts over the entire length of the brush, slide over the core wire during twisting, so that the final distribution of the number of bristles per turn is regular from one end to the other of the brush.

The present invention therefore has for its object a brush for applying mascara to the eyelashes, constituted by a core formed from a twisted metal wire, the twists of which trap the bristles of the brush, said bristles being arranged in a substantially regular manner between said twists, and having a cross section included in a circular envelope, the diameter of which is between 0.12 and 0.25 mm, characterized in that the number of bristles per turn is between 5 and 9, said bristles forming substantially a single-layer helical ply, in which each bristle has a substantially radial orientation, the angle between two adjacent bristles of the ply being substantially constant to about 20%.

The bristles of the brush according to the invention may have a cross section of any shape, and in particular a circular, square, rectangular, hexagonal, octagonal or oval section.

In a preferred embodiment, the core wire has a diameter of between 0.2 and 0.9 mm; the pitch of a turn of the helical sheet is generally between 1.5 and 3.5 mm. The maximum diameter of the peripheral surface of the brush is advantageously between 5 and 12 mm; the peripheral surface of the brush is defined as being the surface on which all the ends of the bristles of the brush are found.

In a first embodiment, the peripheral surface of the brush is cylindro-conical, conical, cylindrical or in the shape of a bud; advantageously, the cross section of the peripheral surface of the brush is then circular. In another embodiment, the cross section of the peripheral surface of the brush is, at least in certain areas of the brush, defined by a curve whose distance from the trace of the core in said cross section is not constant. In all cases, the conventional manufacturing process makes it possible to obtain a cylindrical brush, the peripheral surface of which is conformed as desired by grinding and / or milling. On the brushes according to the invention, the ends of at least part of the bristles of the brush can therefore be ground to have the particular conformations which can be imparted by grinding at the ends of the bristles.

In a preferred embodiment, it is provided that, for at least one zone of the brush, the distance from the ends of two adjacent bristles of the helical sheet of bristles is substantially equal to the pitch of a turn of the helical sheet of bristles in said area. In particular for a brush zone whose peripheral surface is a cylinder of revolution, it is preferred that the number of bristles per turn is constant. For a brush area, the peripheral surface of which is a surface of revolution whose cross section has a variable diameter, it can be provided that the number of bristles per turn is an increasing function of said diameter. Advantageously, the sizing of the brushes according to the invention is such that the minimum distance between the ends of 2 adjacent bristles is at least 0.8 mm, it being understood that this distance can vary over the same brush according to the shape and size of the peripheral surface of said brush.

To better understand the object of the invention, we will now describe, by way of purely illustrative and non-limiting example, an embodiment and implementation shown in the accompanying drawing.

• la figure 1 représente schématiquement une vue latérale d'une spire d'une brosse selon l'invention comportant 9 poils par spire ;
• la figure 2 représente schématiquement le peigne sur lequel on met en place les poils pour la fabrication de la brosse selon l'invention ainsi que le fil en épingle à cheveux, qui vient saisir les poils mis en place sur le peigne.

On this drawing :

• Figure 1 schematically shows a side view of a turn of a brush according to the invention comprising 9 bristles per turn;
• FIG. 2 schematically represents the comb on which the bristles are put in place for the manufacture of the brush according to the invention as well as the hairpin wire, which comes to grip the hairs placed on the comb.

Referring to Figure 1, we see that there is shown a brush having 9 bristles per turn. The core of the brush consists of a twist of a wire 1 of circular cross section and diameter 0.5 mm. In their twist of wire are trapped by their central area hairs made of Nylon-6.10 having a solid circular cross section with a diameter of 0.15 mm. Each bristle, designated by the reference 2, is gripped in its central part by the twisted wire 1 and the set of bristles defines a single-layer helical sheet, the bristles being regularly spaced from each other, that is to say that 'A bristle 2 forms with the adjacent bristles an angle which is constant to within 20% all along the helical sheet formed.

The manufacture of such a brush is carried out by the implementation of the conventional manufacturing process which is used industrially for all types of brush with twisted core. To do this, in a first step, the core wire 1 is bent in the form of a hairpin. Tufts of bristles are placed in the slots 3a of a comb 3. The pin is made to slide constituted by the wire 1 relative to the comb 3, so that the protruding parts of the tufts of bristles 2 are positioned between the two branches of the pin, the plane of the two branches of the pin being substantially the median transverse plane of all of the tufts of hair 2. The two ends of the pin formed by the wire 1 are then grasped, the comb is moved away and the two ends of the pin are rotated to create the twist that constitutes the soul of the brush. In this twisting operation, the bristles are evenly distributed between the twisted wires, so that the brush after twisting has a regular distribution of bristles although initially the bristles were placed in tufts corresponding to each of the comb slots. 3.

In this exemplary embodiment, the desired brush has a length of 26 mm. A comb 3 was used, consisting of a 4 mm thick steel blade having 18 slots 3a each having a width of 1 mm, two successive slots being separated by rectangular teeth having a width of 0.7 mm. In each of the slots, about 12 bristles 2 are put in place, each having a length of 20 mm, and the procedure is as indicated above to obtain a brush according to the invention. This brush has 20 turns and 9 bristles per turn; each turn of the helical sheet therefore occupies 0.5 mm along the length of the brush. After twisting has been carried out, the brush is ground or mowed to give it a cylindro-conical shape, the cylindrical part of which constitutes the peripheral surface part which has the maximum diameter; this maximum diameter is 7.5 mm. With the values given above for the various parameters involved, it can be seen that, on the cylindrical part of the brush, the ends of two adjacent bristles of the helical sheet are substantially 1.2 mm from each other ; this distance is substantially constant since the bristles 2 all have a substantially radial orientation and are spaced angularly from each other by a value of about 40 °, the variation of this angle all along the helical sheet being less than 20%.

The bristles of the brush are made of polyamide 6-10 as previously indicated but the bristles of the brush according to the invention can also be made of polyamide 6-6 or polyamide 6-12 or polyamide 6 or polyamide 11 or in polyester or polytetrafluoroethylene. These raw materials may or may not be added with agents improving the sliding and wettability characteristics of the material.

It can therefore be seen that, on the brush according to the invention, the ends of the bristles 2 are substantially equidistant from each other on the cylindrical peripheral surface of the brush. It is very clear that this equidistance is no longer observed on the conical part of the peripheral surface of the brush since the outside diameter of the brush decreases while the number of bristles per turn is kept constant. In a variant, one could, of course, consider reducing the number of bristles per turn as the outside diameter of the brush is reduced on the conical part of the latter so as to maintain the equidistance of the ends hairs.

It has been found that the makeup obtained with such a brush is of perfect quality because the eyelashes can penetrate between the bristles of the brush so that the brush performs a function of combing the eyelashes. In addition, the load of mascara product is smoothed over the entire length of the eyelash, taken in isolation, which makes it possible to have an eyelash lengthening effect. The load of makeup product on the eyelash can be high because the eyelash can penetrate the brush as far as the vicinity of the core, that is to say in the least wrung area of the brush, therefore in the area where the greatest amount of makeup is found. Finally, the constancy of the spacing of the bristles whatever the angle formed between the eyelashes and the axis of the brush makes it possible to obtain a perfectly homogeneous makeup.

Claims (13)

1. Brush for applying mascara to the eyelashes, consisting of a core formed of a twisted metal wire (1), the twists of which trap between them the bristles (2) of the brush, the said bristles (2) being arranged substantially evenly between the said twists and having a cross-section which falls within a circular envelope the diameter of which is between 0.12 and 0.25 mm, the brush being characterized in that the number of bristles (2) per turn is between 5 and 9, the said bristles substantially forming a single-layer helical sheet in which each bristle points substantially radially, the angle between two adjacent bristles in the sheet being substantially constant, to within about 20%.
2. Brush according to Claim 1, characterized in that the cross-section of the bristles is circular, square, rectangular, hexagonal, octagonal or oval.
3. Brush according to one of Claims 1 and 2, characterized in that the core wire has a diameter of between 0.2 and 0.9 mm.
4. Brush according to one of Claims 1 to 3, characterized in that the pitch of one turn of the helical sheet is between 1.5 and 3.5 mm.
5. Brush according to one of Claims 1 to 4, characterized in that the maximum diameter of the peripheral surface of the brush is between 5 and 12 mm.
6. Brush according to one of Claims 1 to 5, characterized in that the peripheral surface of the brush is cylindro-conical, conical, cylindrical, or bud-shaped.
7. Brush according to one of Claims 1 to 6, characterized in that the cross-section of the peripheral surface of the brush is circular.
8. Brush according to one of Claims 1 to 6, characterized in that the cross-section of the peripheral surface of the brush is, at least in some regions of the brush, defined by a curve, where the distance of the said cross-section to the line of the core is not constant.
9. Brush according to one of Claims 1 to 8, characterized in that, for at least one region of the brush, the distance between the ends of two adjacent bristles in the helical sheet of bristles is substantially equal to the pitch of a turn of the helical sheet of bristles in the said region.
10. Brush according to Claim 9, characterized in that the number of bristles per turn is constant.
11. Brush according to Claim 9, in which the peripheral surface of one region of the brush is a surface which has symmetry of revolution, the cross-section of which has a variable diameter, characterized in that the number of bristles per turn in the said region is an increasing function of the said diameter.
12. Brush according to one of Claims 1 to 11, characterized in that the ends of at least some of the bristles of the brush are ground.
13. Brush according to one of Claims 1 to 12, characterized in that the ends of two adjacent bristles of the brush are more than 0.8 mm apart.

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