BRUSH FOR APPLYING A COMPOSITION TO THE EYELASHES OR EYEBROWS

Description

TECHNICAL FIELD

The present invention relates to applicators for applying a cosmetic, makeup or care, product to the eyelashes and/or eyebrows, in particular mascara, and to packaging and application devices having a container containing the product to be applied and the applicator.

BACKGROUND

The container is conventionally provided with a wiping member that wipes the stem of the applicator as it is withdrawn from the container. The behavior of the applicator member on passing through the wiping member depends on numerous factors, such as the shape and nature of the lip of the wiping member, the joining part between the stem and the applicator member, and the arrangement of the application elements on the applicator member.

A compromise needs to be found with regard to the quantity of product that is left on the applicator member for application of makeup. Excessive wiping of the applicator member causes the latter to be insufficiently loaded and obliges the user to frequently dip the applicator back into the container. Insufficient wiping leaves an excess of product that is difficult to manage and may result in clumps of product on poorly separated eyelashes.

The application WO2018/099865 A1 discloses a brush for applying a cosmetic product to the eyelashes and/or eyebrows, having:

• • a core made of plastics material, having a longitudinal axis,
  • spikes carried by the core, including at least a first row of spikes extending longitudinally, this row having a succession of at least four consecutive spikes disposed at respective abscissae x₁ to x₄ along the longitudinal axis of the core, where d₁=x₂−x₁, d₂=x₃−x₂, d₃=x₄−x₃ and d₁, d₂ and d₃ are different in pairs. The spike of abscissa x₁ is not necessarily the first spike in the row starting from the proximal end of the brush.

The application WO 2010/007588 A2 discloses a brush injection molded from plastics material, with “fanned” orientations of at least a part of the spikes when the brush is viewed from the side.

Injection-molded brushes having a curved core and a radial implantation of the spikes with respect to the core have also been proposed.

SUMMARY OF THE INVENTION

There is a need to further improve applicators for applying a product to the eyelashes and/or eyebrows, in order to improve the performance thereof, and more particularly to promote the creation on the applicator member of zones laden with product, which allow easy application of makeup and rapid and abundant loading of the eyelashes and/or eyebrows, to give them volume initially, while retaining a high capacity to separate the eyelashes and/or eyebrows in a second makeup step.

The invention aims in particular to propose a brush that has good makeup performance aspects in terms of loading the eyelashes with product and separating them.

The invention aims to meet this need and the subject thereof, according to a first of its aspects, is a brush for applying a cosmetic composition to the eyelashes and/or eyebrows, having:

• • a core, preferably made of plastics material, having a longitudinal, preferably rectilinear axis,
  • a plurality of rows of spikes disposed around the core and along the latter, where, for at least each of a number k of said rows, where k is greater than or equal to 2, at least three successive spikes in this row, of respective ranks p, p+1 and p+2, have elongation axes that make respective angles a_p, a_p+1 and a_p+2 at their base with the longitudinal axis of the core, where p is an integer between 1 and n−3, where n denotes the number of spikes in the row, at least two of the angles a_p, a_p+1 and a_p+2 being different, at least one spike of the same rank p having a different orientation a_p for at least two of these k rows.
    The number k of rows in question is greater than or equal to 2, better still greater than or equal to E(m/2), where m is the total number of rows of the brush, even better still equal to m, E denoting the entire part.
    The invention makes it possible to obtain a distribution of the spikes that is favorable to obtaining a compromise between the performance aspects of loading the eyelashes with product, combing and curling eyelashes.
    In particular, in a preferred implementation of the invention, the distribution of the orientations of the spikes within at least a part of the rows of spikes of the brush approaches a pseudo-random distribution.
    The brush may have two rows of consecutive spikes with different configurations, and the other rows of spikes may be formed by the repetition of these two rows, with one alternating with the other around the longitudinal axis of the brush.
    In a variant, the brush has at least three rows with different respective configurations, or even at least E(m/2) rows with different respective configurations, and at a push, all the rows may have different configurations.
    Preferably, the rows of spikes are all parallel to the longitudinal axis of the core.
    Preferably, for at least one row of spikes and preferably for each row of spikes, the spacing between the spikes in the row at their base and/or at their peak is not regular. The distance between the abscissae at the peak of two consecutive spikes may vary from one pair of consecutive spikes to the next. Preferably, the spacing at the base of the spikes in at least two of the k rows is not constant. In particular, it may be the case that, for four consecutive spikes in at least one row, the peaks of which are disposed at respective abscissae x_m+1 to x_m+4 along the longitudinal axis of the core, where s₁=x_m+2−x_m+1, s₂=x_m+3−x_m+2, s₃=x_m+4−x_m+3, s₁, s₂ and s₃ are different in pairs, when m is an integer. The implantation of the spikes may be in accordance with the teaching in the application WO2018/099865 A1.
    The abscissa of a spike measured at its peak corresponds to the distance, measured along the longitudinal axis of the core, between the peak and a reference plane perpendicular to the longitudinal axis of the core. The abscissae increase from the proximal end of the applicator member to the distal end thereof.
    The fact that there is both a non-regular distribution in the change of the abscissae of the spikes at their base and/or at their peak within the rows and a different change from one row to another, and also a non-regular distribution of the orientations of the spikes, makes it possible to further increase the variety of configurations formed by the spikes at the surface of the brush. The outer surface of the brush may have the appearance of a jumble of spikes without a regular geometric distribution, even though the spikes of the brush are obtained by molding material and not by way of fibers held between turns of a twisted core. The spikes may in particular be molded with the core, preferably from one or more thermoplastic materials.
    Preferably, for at least two consecutive rows of spikes, at least a part of the spikes in one row crosses at least a part of the spikes in the other row, when the brush is viewed from the side, in a direction perpendicular to its longitudinal axis. Such crossings form grooves or Vs in which the eyelashes can fit, and make possible in particular to spread the composition on the surface thereof.
    Preferably, the distances between the peaks of at least three consecutive spikes in at least one row are different. The variability of this distance results advantageously from a variability in the height of the spikes, in their orientation and in the distance between them at their base. Thus, preferably, at least one row, and better still each row of spikes has spikes of which the height varies, the orientation varies and the spacing to the adjacent spikes varies. It is possible in particular to have fewer than four spikes, better still fewer than three spikes, even better still fewer than two spikes, within one row that have the same heights. In the same way, it is possible to have fewer than four spikes, better still fewer than three spikes, even better still fewer than two spikes, within one row that have the same orientations. For at least one row, and preferably for the majority and better still for all of the rows, the angles a_p, a_p+1 and a_p+2 are preferably all different, for at least E(n/2) different values of p, E denoting the entire part. The angles a_p, a_p+1 and a_p+2 may in particular all be different for any value of p between 1 and n−3.
    For at least two of the k rows, and in particular for each of the k rows, there may be one or more of the following characteristics:
  • the number N_f of spikes oriented toward the front and the number N_r of spikes oriented toward the rear preferably satisfy the relationship 0.3<N_f/N_r<2.5, where preferably N_f/N_r is other than 1,
  • the number of successive spikes that are all oriented either toward the front or toward the rear is preferably less than or equal to 6,
  • the number N_f of spikes oriented toward the front and the number N_r of spikes oriented toward the rear satisfy the relationship N_f/N_r>1.1 or N_r/N_f>1.1,
  • the number of spikes oriented toward the front for which there exists a corresponding spike oriented toward the rear with the same angle in terms of absolute value is less than or equal to 1, and better still is strictly less than 1,
  • the number of spikes oriented perpendicularly to the longitudinal axis of the brush is less than or equal to 4, in particular less than or equal to 3, or even zero, these spikes oriented in this way preferably not being consecutive,
  • the length of the spikes in the row varies,
  • the number of pairs of consecutive spikes in which the two spikes are both oriented toward the front or are both oriented toward the rear is less than or equal to 50% of the total number of pairs of consecutive spikes in the row,
  • the number of pairs of consecutive spikes in which the two spikes are oriented with opposite orientations toward the front and toward the rear, or vice versa, is less than or equal to 75% of the total number of pairs of consecutive spikes in the row,
  • the number n of spikes in the row is greater than or equal to 10, better still between 15 and 25,
  • the distances between peaks of consecutive spikes in a row are different for at least half of the pairs of consecutive spikes in this row, and better still for all of the pairs in this row,
  • the distances d_i and d_i+1 between the peaks of three consecutive spikes with respective abscissae x_i, x_i+1 and x_i+2 in the row satisfy d_i< >d_i+1,
  • when the brush is viewed from the side in a direction perpendicular to its longitudinal axis, at least a part of the spikes in one row crosses those in the adjacent row, with preferably at least h spikes out of then in the row crossing another spike in the adjacent row, where preferably h/n> 1/10,
  • when the brush is viewed from the side in a direction perpendicular to its longitudinal axis, at least a part of the spikes in one row does not cross any spike in the adjacent row, with preferably at least g spikes out of the n in the row not crossing another spike in the adjacent row, where preferably g/n>¼,
  • for each of the rows, more than four consecutive spikes are all oriented either toward the front or toward the rear,
  • the number of spikes oriented toward the front is greater than that of the spikes oriented toward the rear for one of the rows, while the opposite is the case for a consecutive row,
  • the number of changes in orientation of the spikes from the front to the rear or vice versa within one row is greater than or equal to ¼ of the total number of spikes in the row and less than or equal to ½,
  • the number of pairs of consecutive spikes within one row that have a width that, for the first spike in the pair, increases with respect to the preceding one and, for the second spike in the pair, decreases with respect to the preceding one, or, for the first spike in the pair, decreases with respect to the preceding one and, for the second spike in the pair, increases with respect to the preceding one, is greater than or equal to ⅓ of the total number of spikes in the row and less than or equal to ⅘,
  • the number of spikes at a time where two consecutive spikes are the same width may be less than or equal to 2, and it is possible for at least one of the rows not to have any spike that follows another with the same width,
  • the ratio between the number of spikes oriented toward the front and the total number of spikes within one row is between 1/4 et ⅔, or even between ¼ and ½ or between ½ et ⅔ with respect to the total number of spikes in this row,
  • the ratio between the number of spikes oriented toward the rear and the total number of spikes within one row is between ⅓ and ⅔,
  • the orientations of the elongation axes of the spikes with respect to the longitudinal axis of the brush are between 70° and 110°,
  • the widths of the spikes are between 0.15 and 0.35 mm, better still between 0.17 and 0.3 mm,
  • the gaps w between consecutive spikes at their base are between 0.1 and 1.8 mm, with an average of between 0.75 mm and 1.25 mm,
  • the number of times where one spike of the same rank has an opposite orientation to that of a spike of the same rank in the consecutive row is greater than or equal to ½ with respect to the total number of spikes in this row, and preferably less than or equal to ¾,
  • the number of times where one spike of the same rank has an orientation in the same direction, toward the front or toward the rear, as that of a spike of the same rank in the consecutive row is greater than or equal to ¼ with respect to the total number of spikes in this row, and preferably less than or equal to ½,
  • the average of the inclinations of the spikes within one row is between 80 and 100°, in particular between 90° and 100°,
  • the standard deviation between the orientations of the spikes within one row is between 5 and 15°.
    When the brush is viewed from the side in a direction perpendicular to its longitudinal axis, at least a part of the spikes in one row may cross those in the adjacent row, and thus form outwardly open grooves, with preferably at least h spikes out of the n in the row crossing another spike in the adjacent row, where preferably h/n> 1/10, or even ⅓.
    When the brush is viewed from the side in a direction perpendicular to its longitudinal axis, it is possible for at least a part of the spikes in one row not to cross any spike in the adjacent row, with preferably at least g spikes out of the n in the row not crossing another spike in the adjacent row, where preferably g/n>⅓, or even ½. It is thus possible for spikes to remain on the brush that make it easier for the eyelashes to penetrate close to the core. The spikes that cross preferably have opposite orientation, meaning that one of the spikes is oriented toward the front and the other spike, in the adjacent row, toward the rear.
    Preferably, the elongation axes of the spikes in at least two of the k rows, and better still in each of the rows, are all contained in a single plane, preferably a radial plane containing the longitudinal axis of the brush. This makes it easier to mold the brush with the aid of a multiple-shell mold. All of the spikes in a single row may have faces that lie in a single plane.
    Preferably, fewer than j row(s) comply with one and the same sequence of values of angles a of the elongation axes, starting from the rear end of the row toward the front end, j being less than or equal to E(m/2), m being the total number of rows, better still j being less than or equal to 2, even better still less than or equal to 1. The brush may thus lack symmetry with respect to its longitudinal axis or with respect to a median plane containing the latter. The brush may also lack, as regards the implantation of the spikes, a plane of symmetry perpendicular to the longitudinal axis of the brush.
    The total number m of rows of spikes for the brush is preferably between 6 and 20, better still between 12 and 20, even better still between 14 and 20, in particular 16 or 18.
    Preferably, with f being the total number of spikes of the brush and q the total number of values of different orientations a_p,y, the ratio q/f is greater than or equal to 50%, better still greater than or equal to 60%. In other words, the brush has relatively few spikes of which the orientation a with respect to the longitudinal axis of the core is the same.
    At least a part, better still all of the spikes have at least one edge, better still two edges, in particular a flat face and a face that is convex toward the outside. All of the spikes of at least two of the k rows, and preferably all of the rows, have a flat face contained in a single plane for the row, as mentioned above.

A further subject of the invention, independently or in combination with the above, is a brush for applying a cosmetic composition to the eyelashes and/or eyebrows, having:

• • a core, preferably made of plastics material, having a longitudinal, preferably rectilinear axis,
  • a plurality of rows of spikes disposed around the core and along the latter, where, for at least each of a number k of said rows, where k is greater than or equal to 2, at least three successive spikes in this row, of respective ranks p, p+1 and p+2, have elongation axes that make respective angles a_p, a_p+1 and a_p+2 at their base with the longitudinal axis of the core, where p is an integer between 1 and n−3, where n denotes the number of spikes in the row, at least two of the angles a_p, a_p+1 and a_p+2 being different, at least 25%, better still at least 50%, of the pairs of consecutive spikes for at least one of the k rows, better still for each of the k rows, having spikes with opposite orientations.

A further subject of the invention, independently or in combination with the above, is a brush for applying a cosmetic composition to the eyelashes and/or eyebrows, having:

• • a core, preferably made of plastics material, having a longitudinal, preferably rectilinear axis,
  • a plurality of rows of spikes disposed around the core and along the latter, where, for at least each of a number k of said rows, where k is greater than or equal to 2, at least three successive spikes in this row, of respective ranks p, p+1 and p+2, have elongation axes that make respective angles a_p, a_p+1 and a_p+2 at their base with the longitudinal axis of the core, where p is an integer between 1 and n−3, where n denotes the number of spikes in the row, f is the total number of spikes of the brush and q is the total number of values of different orientations a_p,y, the ratio q/f being greater than or equal to 50%, better still greater than or equal to 60%, y being the number of the row.

A further subject of the invention is a device for packaging and applying a cosmetic composition to the eyelashes and/or eyebrows, having:

• • a container containing the composition to be applied,
  • a brush according to the invention, as defined above.
    A further subject of the invention is a method for cosmetically treating the eyelashes and/or eyebrows, involving applying a cosmetic composition to the eyelashes and/or eyebrows with the aid of a brush according to the invention, as defined above, or a device according to the invention, comprising such a brush.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be understood better from reading the following detailed description of a non-limiting implementation example thereof and from studying the appended drawing, in which:

FIG. 1 schematically shows, in partial longitudinal section, an example of a packaging and application device according to the invention,

FIG. 2 shows a side view of the brush, on its own,

FIG. 3 is a face-on view of the brush in FIG. 2,

FIG. 4 is a longitudinal section through the brush in FIG. 2,

FIG. 5 shows a detail of the implantation of the spikes,

FIG. 6 is a view of the implantation of the spikes on the brush, after the surface of the core has been flattened,

FIG. 7 is a perspective view of the brush,

FIG. 8 is a perspective view of a brush variant according to the invention,

FIG. 9 is a face-on view of the brush along IX in FIG. 8,

FIG. 10 is a longitudinal section through the brush in FIG. 8 in the plane of a row, and

FIG. 11 is a view, similar to FIG. 10, in the plane of a row consecutive to the one in that figure.

DETAILED DESCRIPTION

FIG. 1 illustrates a packaging and application device 1 having a container 3 containing a product P to be applied and an applicator 2 for applying the latter.

In this example, the container 3 has a neck 4 that receives a wiping member 6, in a manner known per se.

The applicator 2 has a gripping member 5, which also forms a closure cap for the container 3, and bears a stem 7, provided at its opposite end from the gripping member 5 with a brush 10 according to the invention, which is shown on its own in FIG. 2.

The wiping member 6 is for example a wiping member having an elastomer lip, the inside diameter of which corresponds to that of the stem.

The brush 10 is made of thermoplastic material, preferably by injection molding, but the invention is not limited to a particular material for producing the brush.

The brush 10 has a core 11, and spikes 12 that protrude from the core.

The core 11 is extended at one end by an end piece 13 for fixing the brush 10 in the stem 7.

The spikes 12 are organized on the brush 10 in rows 14, of which there are for example sixteen, as can be seen in FIG. 3.

All of the spikes 12 in an i^th row 14 are oriented substantially on a single radial plane R_i containing the longitudinal axis X of the brush 10, as illustrated in particular in FIG. 3.

Within this i^th row 14, the spikes 12 are identified by their rank p from the proximal end 15 of the brush 10 and by the abscissa x_p,i at their peak from a reference plane, as illustrated in FIG. 5.

The angle that the elongation axis Y of a spike 12 of rank p in one row i makes with respect to the longitudinal axis X of the core is denoted a_p,i. This angle is measured at the base of the corresponding spike. Preferably, the elongation axis Y of a spike is rectilinear. The elongation axis Y of a spike 12 is the axis that passes through the centers of mass of its cross section, from the base at which the spike 12 is attached to the core to its peak. Where necessary, the angle a_p,i is measured in projection in a plane that contains the longitudinal axis X of the core and the axis of the row, a value of 90° meaning that the elongation axis Y of the spike 12 is contained in a plane perpendicular to the longitudinal axis X of the core 11, a value less than 90° that the spike is oriented toward the proximal end of the core, that is to say toward the stem 7 that supports the brush 10 (i.e. toward the rear), and a value greater than 90° that the spike is oriented toward the distal end of the core (i.e. toward the front).

The width of a spike 12 of rank p in a row of order i at its base is denoted l_p,i This width is measured parallel to the longitudinal axis X of the core.

In the example in question, the spikes 12 each have a semi-conical shape, with a flat face 22. All of the spikes 12 in one and the same i^th row 14 have their flat faces contained in a single plane R_i, which is preferably a radially oriented plane, as can be seen in FIG. 3.

It can be seen in FIGS. 4 and 5 in particular that, for at least two consecutive rows of spikes, at least a part of the spikes in one row crosses at least a part of the spikes in the other row, when the brush is viewed from the side, in a direction perpendicular to its longitudinal axis, as in these figures. Such crossings form grooves or Vs 20 in which the eyelashes can fit, and make possible in particular to spread the composition on the surface thereof.

The brush 10 for example has the following characteristics: for three successive rows 14 of spikes, x denotes the abscissa of the peak of the spike of rank p, a the inclination of its elongation axis Y with respect to the longitudinal axis X of the core at its base, and l the width at its base, measured in the direction of the longitudinal axis X. Since each spike 12 has a semicircular cross section, with a flat face contained in the corresponding radial plane R_i, the width at the base of the spike also corresponds to the diameter of the spike at its base.

	TABLE 1
	Row	Spikes	x	Angle a	l

	Row 1	Spike 1	1.36	69.51	0.78
		Spike 2	3.76	89.8	0.5
		Spike 3	5.32	100.93	0.74
		Spike 4	6.17	93.82	0.5
		Spike 5	7.01	74.74	0.51
		Spike 6	8.97	94.82	0.47
		Spike 7	9.96	86.79	0.47
		Spike 8	11.55	94.82	0.47
		Spike 9	13.08	108.86	0.48
		Spike 10	14.68	108.02	0.73
		Spike 11	15.92	97.83	0.48
		Spike 12	16.76	79.67	0.75
		Spike 13	19.12	95.87	0.8
		Spike 14	20.77	82.69	0.8
		Spike 15	21.87	84.77	0.47
		Spike 16	23.14	94.83	0.44
		Spike 17	24.17	94.83	0.39
		Spike 18	24.8	79.61	0.53
	Row 2	Spike 1	0.6	73.82	0.51
		Spike 2	1.97	95.02	0.5
		Spike 3	2.96	86.99	0.5
		Spike 4	4.55	95.02	0.5
		Spike 5	6.08	109.06	0.49
		Spike 6	7.68	108.21	0.73
		Spike 7	8.45	84.98	0.5
		Spike 8	9.92	93.03	0.47
		Spike 9	10.76	79.86	0.7
		Spike 10	13.12	96.08	0.72
		Spike 11	14.77	82.89	0.77
		Spike 12	15.22	71.8	0.71
		Spike 13	17.44	81.97	0.5
		Spike 14	18.37	84.97	0.53
		Spike 15	19.94	95.02	0.54
		Spike 16	21.82	101.13	0.69
		Spike 17	22.34	81.96	0.45
		Spike 18	23.62	96.09	0.58
		Spike 19	24.62	101.16	0.52
		Spike 20	25.04	81.95	0.38
	Row 3	Spike 1	0.55	98.91	0.49
		Spike 2	1.38	81.74	0.5
		Spike 3	2.92	97.83	0.5
		Spike 4	3.76	79.67	0.76
		Spike 5	6.12	95.88	0.74
		Spike 6	7.77	82.69	0.76
		Spike 7	9.23	71.6	0.69
		Spike 8	11.45	81.77	0.48
		Spike 9	12.38	84.77	0.48
		Spike 10	13.94	94.82	0.5
		Spike 11	14.97	94.83	0.5
		Spike 12	15.61	79.65	0.77
		Spike 13	16.86	89.8	0.49
		Spike 14	18.32	100.92	0.77
		Spike 15	19.17	93.82	0.51
		Spike 16	20.01	74.74	0.55
		Spike 17	22.28	108.87	0.46
		Spike 18	22.76	89.8	0.42
		Spike 19	24.03	108.05	0.54
		Spike 20	24.41	74.72	0.4

The values a, x and l are only given for three rows by way of example, and the values for the other rows are chosen so as to comply with one or more of the conditions given above, and thus have, in these remaining rows, the same characteristics as for the first three rows.
It will be noted on studying this table that, within one row of spikes 12 of a brush 10 according to the invention, spikes having orientations toward the rear (a<90°) and toward the front (a>90°) are found.
It can be seen that, for the three rows 14 in the above table, at least three successive spikes in each row, of respective ranks p, p+1 and p+2 and with peaks of abscissae x_p, x_p+1 and x_p+2 along the longitudinal axis of the brush, have elongation axes Y that make respective angles a_p, a_p+1 and a_p+2 with the longitudinal axis X at their base, where p is an integer between 1 and n−3, where n denotes the number of spikes in the row, where at least two of the angles a_p, a_p+1 and a_p+2 are different.
In addition, at least one spike 12 of the same rank p has a different orientation a_p from one row 14 to the next.
In addition, it can be seen that, for these rows, the number N_f of spikes oriented toward the front and the number N_r of spikes oriented toward the rear satisfy the relationship 0.3<N_f/N_r<2.5.
Thus, for row 1: N_f=10 and N_r=8, i.e. N_f/N_r=1.25, for row 2: N_f=10 and N_r=10, i.e. N_f/N_r=1, for row 3: N_f=9 and N_r=11, i.e. N_f/N_r=0.81.
It can also be seen that, for at least some rows, the number N_f of spikes oriented toward the front and the number N_r of spikes oriented toward the rear satisfy the relationship N_f/N_r>1.1 or N_r/N_f>1.1. In other words, the number of spikes oriented toward the front is different than the number of spikes oriented toward the rear, within one row.
In the example in question, the number of successive spikes 12 that are all oriented either toward the front or toward the rear is less than or equal to 6 for each of the rows. For example, the spikes of ranks 8 to 11 in the first row are all oriented toward the front, while the spikes of ranks 7 and 12 in this same row are oriented toward the rear.
Still in the example in question, the number of spikes oriented toward the front for which there exists a corresponding spike oriented toward the rear with the same angle in terms of absolute value is less than or equal to 1 for at least some rows. For example, this number is zero for the first row.
The number of spikes oriented perpendicularly to the longitudinal axis of the brush is zero for at least a part of the rows in the example in question, or even for all of the rows.
The number of pairs of consecutive spikes in which the two spikes are both oriented toward the front or are both oriented toward the rear may be less than or equal to 75% of the total number of pairs of consecutive spikes in the row, for at least some rows. Preferably, this proportion is greater than 25% and less than 50%.
For example, for the first row, which has 18 spikes and 17 pairs of consecutive spikes, only seven of them, which are formed by the pairs of spikes (1,2), (3,4), (8,9), (9,10), (10,11), (14,15), (16,17), concern spikes that are both oriented toward the front or toward the rear.
This results in a wide variety of orientations of the spikes on the brush.
The number of pairs of consecutive spikes in which the two spikes are oriented with opposite orientations toward the front and toward the rear, or vice versa, may be less than or equal to 75% of the total number of pairs of consecutive spikes in the row, for at least one row, and preferably each of the rows. Preferably, this proportion is greater than 25%.
For example, for the first row, the following pairs have two consecutive spikes with opposite orientations: (2,3), (4,5), (5,6), (6,7), (11,12), (12,13), (13,14), (15,16), (17,18), i.e. a ratio of 9/17=about 0.52. This is thus different than a fanned disposition of the spikes, which does not have such successions of spikes having opposite orientations.
It can also be seen in FIGS. 4 and 5, for example, that, for at least a part of the successive spikes of ranks i, i+1 and i+2 in the row, the distances between peaks of these spikes satisfy the relationship d_i< >d_i+1. Also, |x_i+2−x_i+1|< >| x_i+1−x_i|.
FIG. 6 shows the implantation of the spikes 12 on the core 11, and also their size.
It can be seen that, within at least one row 14, the size of the spikes varies, with, for example, for row 1, successions of three or four spikes with a small size less than or equal to 0.5 mm and a succession of three spikes with a large size greater than 0.5 mm, the spacings between the spikes also varying. For the first row, there are for example eight spikes with a large size, greater than 0.5 mm in diameter at their base, and ten spikes with a small size, less than or equal to 0.5 mm in diameter at their base. The spacing between the centers of the spikes, given by the difference between the abscissae of two consecutive spikes, varies for example from less than 1 mm for some pairs of consecutive spikes to more than 1 mm for others.
The deviations |x_i+1−x_i| between the abscissae of the peaks of the spikes, for i between 0 and n−1, where n is the number of spikes in the row, may vary around an average value of between 1.2 and 1.5 mm, for at least one row, and better still for all of the rows. This variation may take place around a median value of between 1.1 and 1.45 mm. The distribution of these deviations may have a positive coefficient of asymmetry with respect to the average, in particular greater than 0.5.
An embodiment variant of the brush 10 will now be described with reference to FIGS. 8 to 11.
According to this variant, the brush has two arrangements of rows that repeat identically around the longitudinal axis of the brush, alternately.
In this example, the brush has sixteen rows 14, and there are therefore eight rows R_2i, where i is an integer ranging from 1 to 4, which have a first configuration, and eight other rows R_2i+1, with integer i ranging from 0 to 3, which have a second configuration, different than the first, the rows R_2i alternating with the rows R_2i+1 around the longitudinal axis of the brush. FIG. 10 shows a row R_2i and FIG. 11 shows a row R_2i+1.
There are for example the following values, for each of these rows.

TABLE 2
Rank			Spike	Distance wi−1, i
spike row	Abscissa ×	Spike	base	from preceding
(R2i+1)	spike peak	inclination	width	spike

1	1.8	mm	73.62	deg	0.26	mm
2	3.8	mm	86.79	deg	0.3	mm	0.89
3	4.5	mm	80	deg	0.17	mm	0.59
4	6.3	mm	100	deg	0.25	mm	0.31
5	7	mm	70	deg	0.3	mm	1.79
6	9.7	mm	84.78	deg	0.2	mm	1.37
7	11.2	mm	79.66	deg	0.3	mm	1.28
8	13.1	mm	95.88	deg	0.19	mm	0.54
9	15.45	mm	110	deg	0.3	mm	1.06
10	16.8	mm	90	deg	0.18	mm	1.99
11	18.3	mm	100	deg	0.26	mm	0.52
12	19.35	mm	80	deg	0.28	mm	1.59
13	21	mm	88	deg	0.17	mm	0.76
14	22	mm	79.65	deg	0.3	mm	0.98
15	24.2	mm	100	deg	0.22	mm	0.59
16	25	mm	90	deg	0.26	mm	0.85
17	25.5	mm	80	deg	0.17	mm	0.48
18	26.6	mm	90	deg	0.2	mm	0.32

TABLE 3
Rank			Spike	Distance wi−1, i
spike row	Abscissa ×	Spike	base	from preceding
(R2i)	spike peak	inclination	width	spike

1	2.35	mm	69.8	deg	0.3	mm
2	5.3	mm	90	deg	0.19	mm	1.44
3	6	mm	75	deg	0.3	mm	0.98
4	8	mm	95	deg	0.3	mm	0.36
5	9	mm	94.02	deg	0.19	mm	0.56
6	10.5	mm	95.02	deg	0.24	mm	1.02
7	12.3	mm	109.07	deg	0.24	mm	0.57
8	13.4	mm	80	deg	0.35	mm	2.04
9	14.5	mm	86	deg	0.3	mm	0.13
10	16.2	mm	98.03	deg	0.19	mm	0.59
11	17.3	mm	79.84	deg	0.3	mm	1.55
12	19	mm	96.07	deg	0.19	mm	0.37
13	20	mm	80	deg	0.3	mm	1.34
14	22.2	mm	100	deg	0.19	mm	0.67
15	23.2	mm	90	deg	0.21	mm	1.12
16	24.6	mm	95	deg	0.27	mm	0.63
17	26.25	mm	115	deg	0.27	mm	0.49

The abscissa of the spikes corresponds to the distance between their peak and a single reference plane for all of the spikes.
The inclination of a spike corresponds to the angle between the elongation axis of the spike and the longitudinal axis of the core.
The distance from the preceding spike is expressed in mm and corresponds to the minimum gap measured along the longitudinal axis of the core between the spikes in question, at the base of the spikes by which they are attached to the core, as illustrated in FIGS. 10 and 11.
The width at the base of a spike corresponds to the width measured along the longitudinal axis of the core at the base of the spike by which it is attached to the core.
In this example, the spikes 12 have the same shape in section as those of the brush in FIG. 1. The width at the base of the spikes thus corresponds to the width of their flat side.
On studying the above values, it will be seen that each of these two rows has all or some of the following characteristics:

for each of the rows, more than four consecutive spikes are all oriented either toward the front or toward the rear,

there are at most three spikes perpendicular to the longitudinal axis of the core,

there are never two consecutive spikes perpendicular to the longitudinal axis of the core,

the number N_f of spikes oriented toward the front is greater than that N_r of the spikes oriented toward the rear for one of the rows, while the opposite is the case for the other row,

the number of changes in orientation of the spikes from the front to the rear or vice versa within one row is greater than or equal to ¼ of the total number of spikes in the row and less than or equal to ½,

the number of pairs of consecutive spikes within one row that have a width that, for the first spike in the pair, increases with respect to the preceding one and, for the second spike in the pair, decreases with respect to the preceding one (this being the case for example of the pair of spikes of ranks 2 and 3 in the row R_2i+1), or, for the first spike in the pair, decreases with respect to the preceding one and, for the second spike in the pair, increases with respect to the preceding one, is greater than or equal to ⅓ of the total number of spikes in the row and less than or equal to ⅘,

the number of spikes at a time where two consecutive spikes are the same width may be less than or equal to 2, and it is possible for at least one of the rows not to have any spike that follows another with the same width,

the ratio between the number of spikes oriented toward the front and the total number of spikes within one row is between ¼ et ⅔, or even between ¼ and ½ or between ½ et ⅔ with respect to the total number of spikes in this row,

the ratio between the number of spikes oriented toward the rear and the total number of spikes within one row is between ⅓ and ⅔,

the orientations of the spikes are between 70° and 110°,

the widths of the spikes are between 0.15 and 0.35 mm, better still between 0.17 and 0.3 mm,

the gaps w between consecutive spikes at their base are between 0.1 and 1.8 mm, with an average of between 0.75 mm and 1.25 mm,

the number of times where one spike of the same rank has an opposite orientation to that of a spike of the same rank in the consecutive row is greater than or equal to ½ with respect to the total number of spikes in this row, and preferably less than or equal to ¾,

the number of times where one spike of the same rank has an orientation in the same direction, toward the front or toward the rear, as that of a spike of the same rank in the consecutive row is greater than or equal to ¼ with respect to the total number of spikes in this row, and preferably less than or equal to ½,

the average of the inclinations of the spikes within one row is between 80 and 100°, in particular between 90° and 100°,

the standard deviation between the orientations of the spikes within one row is between 5 and 15°,

the number N_f of spikes oriented toward the front and the number N_r of spikes oriented toward the rear satisfy the relationship 0.3<N_f/N_r<2.5, where preferably N_f/N_r is other than 1; in particular, for each of the rows, 0.4<N_f/N_r<⅕,

the number N_f of spikes oriented toward the front and the number N_r of spikes oriented toward the rear satisfy the relationship N_f/N_r>1.1 or N_r/N_f>1.1,

the length of the spikes in the row varies,

the number of pairs of consecutive spikes in which the two spikes are both oriented toward the front or are both oriented toward the rear is less than or equal to 50% of the total number of pairs of consecutive spikes in the row, and in particular is between 25 and 35%,

the number of pairs of consecutive spikes in which the two spikes are oriented with opposite orientations toward the front and toward the rear, or vice versa, is less than or equal to 75% of the total number of pairs of consecutive spikes in the row,

the number n of spikes in the row is between 15 and 25,

the distances between peaks of consecutive spikes in a row are different for at least half of the pairs of consecutive spikes in this row,

the distances d_i and d_i+1 between the peaks of three consecutive spikes with respective abscissae x_i, x₁₊₁ and x_i+2 in the row satisfy d_i< >d_i+1.

Needless to say, the invention is not limited to the examples that have just been described. For example, the orientations of the spikes and the distribution of the sizes of the spikes, and their disposition, may vary within variants that are not illustrated.
The brush may be manufactured by a technique other than injection molding, and from a material other than a thermoplastic material, if necessary.
The spikes may be given a different shape, for example a conical or cylindrical shape or a shape with irregularities or protuberances.