US20250288065A1

US20250288065A1 - Improved retention device

Info

Publication number: US20250288065A1
Application number: US18/862,387
Authority: US
Inventors: Lionel Picot; Kamal AMANI; Stephanie COURTEL
Original assignee: Aplix SA
Current assignee: Aplix SA
Priority date: 2022-05-09
Filing date: 2023-04-28
Publication date: 2025-09-18
Also published as: FR3135195A1; WO2023218136A1; EP4521989A1; JP2025517155A; CN119317377A; FR3135195B1; MX2024013860A

Abstract

Retaining device (1) comprising a base (10), a plurality of retaining elements (20) comprising a rod (30) surmounted by a head (40); in which, for each retaining element (20), in projection in a plane formed by the upper face (12) of the base (10), the lower end (34) of the rod (30) is inscribed within a first circle C1 with center O1, the head (40) is inscribed within a second circle C2 with center O2, said second circle being tangent to one end of the head (40) along the longitudinal direction (MD), the maximum dimension of the head (40) passing through the center of the circle C2 and extending along the longitudinal direction (MD) and/or the transverse direction (CD) is less than 80% of the diameter D2 of the second circle C2.

Description

TECHNICAL FIELD

The present invention relates to the field of retaining devices, in particular hook retaining devices.

PRIOR ART

Hook closing systems are well known and used in many fields of application, leading in fact to the production of multiple shapes of hooks or more generally to multiple shapes of retaining elements intended to cooperate with each other or with complementary elements such as loops.
A recurring issue with such products concerns the retaining force applied, in particular given the greatly reduced dimensions of the hooks and the associated manufacturing constraints.
Indeed, the production of hooks with high resistance naturally leads to oversizing, which is detrimental to the smoothness of the system and therefore to the user's feeling, which is highly penalizing in some fields, in particular in the field of hygiene, and also leads to increased consumption of material, which is penalizing in terms of cost, and also penalizing in terms of manufacture. A recurring issue also concerns the reproducibility of the retaining elements, particularly by taking into account the shortages of some raw materials on a global scale.
The present disclosure aims to address these various issues by proposing a retaining device whose geometry is simpler, more easily reproducible and could in particular be obtained from a wider spectrum of raw materials in light of the shortages of some raw materials on a global scale.

DISCLOSURE OF THE INVENTION

The present invention thus proposes a retaining device, for example for making a self-gripping connection comprising:

- a base extending along a longitudinal direction, having an upper face and a lower face,
- a plurality of retaining elements extending on the upper face of the base, each retaining element comprising a rod surmounted by a head, for example which head is arranged to cooperate with a counterpart in order to form a self-gripping connection; each rod comprising a lower end connected to the base, and an opposite upper end from which the head extends,
- in which, for each retaining element, in projection in a plane formed by the upper face of the base:
- the lower end of the rod is inscribed within a first circle C1 with center O1,
- the head is inscribed within a second circle C2 with center O2 and diameter D2, said second circle being the smallest circle comprising the head, which second circle C2 being tangent to one end of the head along the longitudinal direction and/or the transverse direction
- such that:
- the maximum dimension of the head passing through the center O2 of the circle C2 and extending along the longitudinal direction and/or the transverse direction is less than 80% of the diameter D2 of the second circle C2.

According to one example, the second circle C2 is comprised in the first circle C1.
According to one example, the first circle C1 having a diameter D1, the distance between O1 and O2 is less than or equal to 50% of the diameter D1 of the first circle C1, in particular less than 30%, less than 25%, less than 20%, less than 15%, or less than 10%, and optionally, the distance between O1 and O2 is greater than or equal to 0% of the diameter D1 of the first circle C1, or greater than 0%, or greater than 1%, or greater than 4%. Such a structure implies that the base of the rod and the head are centered or nearly centered relative to each other, and therefore that the rod of the retaining element is straight or substantially straight. This makes it possible to improve the mechanical strength of the retaining element, and to limit its deformations under the effect of shear during its interactions with fibers of a non-woven fabric.
According to one example, it is meant by the second circle C2 is comprised in the first circle C1 that at least 95% of the surface of the circle C2 is comprised in the first circle C1, in particular 98%, in particular 100%.
According to one example, the distance between O1 and O2 is less than or equal to 50% of the diameter D2 of the second circle C2, in particular less than 30%, less than 25%, less than 20%, less than 15%, less than 12%, or less than 10% and optionally, the distance between O1 and O2 is greater than or equal to 0% of the diameter D2 of the second circle C2, or greater than 0%, or greater than 1%, or greater than 4%. Such a structure also implies that the base of the rod and the head are centered or almost centered relative to each other, and therefore that the rod of the retaining element is straight or substantially straight. This makes it possible to improve the mechanical strength of the retaining element, and to limit its deformations under the effect of shear during its interactions with fibers of a non-woven fabric.
According to one example, the distance between O1 and O2 is less than or equal to 100 μm, in particular less than or equal to 75 μm, 50 μm or 30 μm.
According to one example, the upper end of the rod is inscribed within a third circle C3, said circle C3 being comprised in the second circle C2.
According to one example, a non-woven material is secured to the lower face of the base.
According to one example, the ratio of the diameter D2 of the circle C2 and the diameter D1 of the circle C1 is comprised between 0.3 and 0.95 or more specifically between 0.5 and 0.9. Thus, the widest dimension of the head is smaller than the width of the lower end of the rod. The lower end or foot of the rod is thus reinforced, and the shearing or peeling forces applied by a non-woven fabric are distributed to limit the deformation of the rod at the level of its lower end.
According to one example, the retaining elements have a hooking height Ha comprised between 30 micrometers and 120 micrometers, more particularly between 30 micrometers and 70 micrometers, even more particularly between 40 micrometers and 60 micrometers.
According to one example, the retaining elements have a hooking dimension Da, greater than 40 micrometers, in particular greater than 60 micrometers, and/or less than 120 micrometers, in particular less than 100 micrometers. The hooking dimension Da corresponds to the maximum direction between the upper end 32 of the rod 30 and an outer radial end of the head 40, measured along a radial direction relative to a central axis of the rod 30. According to one example, the retaining elements have at least one hooking dimension Da and the radial direction is the machine direction and/or the transverse direction. According to one example, the retaining elements have at least two hooking dimensions Da, one of the hooking dimensions Da having a radial direction along the machine direction and the other of the hooking dimensions Da having a radial direction along the transverse direction. According to one example, the retaining elements have at least two hooking dimensions Da, one of the hooking dimensions Da having a radial direction along the transverse direction and the other of the hooking dimensions Da having a radial direction along the transverse direction.
According to one example, the head has a thickness Hh comprised between 30 micrometers and 70 micrometers, particularly 40 micrometers and 60 micrometers.
According to one example, the rod has a height Ht which is comprised between 150 micrometers and 330 micrometers, particularly between 200 micrometers and 300 micrometers.
According to one example, the ratio of the thickness Hh of the head and the height Ht of the rod is comprised between 0.05 and 0.3, or more particularly between 0.1 and 0.25. Thus, the rod of the retaining element is reinforced, which limits the deformations and optimizes the performance, for example peeling and/or shearing performance.
According to one example, the ratio of the hooking height Ha and the height Ht of the rod is comprised between 0.05 and 0.4, particularly between 0.05 and 0.3, more particularly between 0.1 and 0.25. Such a configuration makes it possible in particular to ensure, during the engagement with the counterpart, easier passage of fibers and/or filaments of the counterpart, in particular of the non-woven counterpart, while allowing sufficient holding of the fibers and/or filaments of the counterpart.
According to one example, the rod has, in side view along the longitudinal direction and/or the transverse direction, a proximal portion extending from the lower end of the rod, a distal portion extending from the upper end of the rod and an intermediate portion arranged between the proximal portion and the distal portion, the distal portion and the proximal portion have, with respect to a straight line perpendicular to the longitudinal direction and to the transverse direction, a curvature greater than the curvature of the intermediate portion.
According to one example, in side view along the longitudinal direction and/or the transverse direction in a view projected in the plane perpendicular to this side view, the rod has two opposite edges (here two opposite outer edges) of which the at least one of the two edges comprises a curvature with an inflection point, or two inflection points or three inflection points or more, for example ten inflection points, the inflection points being distinct, in some cases, each of the two edges comprises a curvature with an inflection point, or two inflection points or three inflection points or more, for example ten inflection points, the inflection points being distinct.
According to one example, in side view along the longitudinal direction and/or the transverse direction in a view projected in the plane perpendicular to this side view, the rod has two opposite edges (here two opposite outer edges) of which the at least one, in some cases both edges, has a general shape of a tilde or an inverted tilde or of an S or an inverted S.
According to one example, in side view along the longitudinal direction and/or the transverse direction, said retaining device has a ratio between the dimension of the upper end of the rod and the dimension of the lower end of the rod comprised between 0.3 and 0.75, or particularly between 0.3 and 0.65, or more particularly between 0.35 and 0.55, or even more particularly between 0.35 and 0.5. Such a structure of the rod makes it possible in particular to facilitate the demolding, while retaining a good capacity for holding fibers of non-woven fabrics and reducing the material consumed.
According to one example, the retaining device is intended to cooperate with loops to make a contact closure. According to one example, along the longitudinal direction and/or the transverse direction, the total number of hooking portions 42 or lobes 42 is comprised between 1 and 4 (inclusive), in some cases between 1 and 3 (inclusive) or between 2 and 4 (inclusive) or between 2 and 3 (inclusive). According to another example, at least two, or at least three, of the hooking portions are connected to each other in a continuous manner, in particular all of the hooking portions are connected to each other in a continuous manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and its advantages will be better understood upon reading the detailed description given below of different embodiments of the invention given as non-limiting examples.

FIG. 1 schematically illustrates a retaining device according to one aspect of the invention.

FIG. 2 is a top photo of a retaining element.

FIG. 3 is another top view to scale of a retaining element.

FIG. 4 is a detailed view to scale of a retaining element.

FIG. 5 is a detailed view to scale of another example of a retaining element.

FIG. 6 is a detailed view to scale of another example of a retaining element.

In all the figures, the common elements are identified by identical numerical references.

DESCRIPTION OF THE EMBODIMENTS

A retaining device is described here with reference to FIGS. 1 to 6 .
The figures represent a retaining device 1 comprising a base 10. This base 10 generally has the shape of a ribbon extending along a longitudinal direction or machine direction MD and a transverse direction CD perpendicular to the longitudinal direction MD.
The longitudinal direction MD is the main direction in which the base 10 extends. In terms of production, this thus corresponds to the direction of displacement of the retaining device 1 in the tooling for its manufacture or shaping.
The base 10 has the general shape of a ribbon of thickness T, and having edges. The longitudinal direction MD is typically parallel to the edges of the base 10, which define the ends of the base 10 along the transverse direction CD.
An upper face 12 and a lower face 14 opposite to the upper face are defined for the base 10, the designations “upper” and “lower” being arbitrary and not restrictive. Within the framework of the present disclosure, the base 10 is represented as being disposed flat. It is however understood that the base 10 is typically flexible, and that the description should therefore not be interpreted in a limiting manner.
The retaining device 1 comprises a plurality of retaining elements 20 extending from the upper face 12 of the base 10. The retaining elements 20 are typically formed in one piece with the base 10. The retaining elements 20 are typically adapted or formed such that the retaining device can cooperate with loops to make a contact closing.
Each retaining element 20 comprises a rod 30 and a head 40.
The rod 30 extends from the upper face 12 of the base 10. This defines a lower end 34 of the rod 30 which is connected to the base 10, and an upper end 32 of the rod 30 opposite to the lower end 34 of the rod 30, and which is the portion of the rod 30 furthest from the base 10.
The rod 30 can for example have a circular, oval, polygonal section or more generally any suitable shape. It is in particular possible to produce a rod 30 having a cross-shaped or “plus”-shaped shaped section. Such a cross-shaped section typically has four ribs substantially evenly distributed, for example evenly, about a central axis of the rod 30, and extending radially about this central axis of the rod 30. More generally, the rod 30 can for example have an oval or square or rectangular section or according to the general shape of a star with X evenly distributed arms, X being comprised between 3 and 10, each arm having a proximal end and a distal end, the proximal ends of each of the arms being contiguous and the distal ends of the arms are all spaced from each other by the same angle.
The section of the rod 30 is typically variable according to the height, the height being measured along a direction perpendicular to the upper face 12 of the base 10. According to one example, the section of the rod 30 is predominantly or strictly decreasing from the lower end 34 of the rod 30 to the upper end 32 of the rod 30.
As an example, if the rod 30 is considered in side view along the longitudinal direction MD and/or the transverse direction CD, the rod 30 has a proximal portion extending from the lower end 34 of the rod 30, a distal portion extending from the upper end 32 of the rod 30 and an intermediate portion arranged between the proximal portion and the distal portion.
According to one example, the section of the rod 30 decreases from the lower end 34 of the rod 30 to the intermediate portion of the rod 30 and increases from this intermediate portion to the upper end of the rod.
The intermediate portion can for example have a constant section, or can have a decreasing section along the direction going from the base 20 to the head 40.
According to one example, the proximal and intermediate portions are delimited from each other by an inversion of curvature, and/or the intermediate and distal portions are delimited from each other by an inversion of curvature. In some cases, the distal portion and the proximal portion then typically have, with respect to a straight line perpendicular to the longitudinal direction MD and to the transverse direction CD, a curvature greater than the curvature of the intermediate portion. Such a shape of the rod 30 with a radius of curvature of the distal portion of the rod less than the radius of curvature of the intermediate portion makes it possible to offer a greater fiber or filament retaining capacity for retaining a loop counterpart.
In some cases, in side view along the longitudinal direction and/or the transverse direction in a view projected in the plane perpendicular to this side view, the limit between the proximal and intermediate portions is defined, along one of the two edges of the rod 30, by the presence of a lower inflection point or along each of the two edges of the rod 30, by the presence of a lower inflection point, and/or, the limit between the intermediate and distal portions is defined, along one of the two edges of the rod 30, by the presence of an upper inflection point, or, along each of the two edges of the rod 30, by the presence of an upper inflection point. In some cases, the straight line connecting the upper inflection points forms the limit between the intermediate and distal portions and/or the straight line connecting the lower inflection points forms the limit between the proximal and intermediate portions. In other cases, the straight line parallel to the base 10 passing through the inflection point closest to the head 40 forms the limit between the intermediate and distal portions and/or the straight line parallel to the base 10 passing through the inflection point closest to the base 10 forms the limit between the intermediate and proximal portions.
According to one example, the height of the distal portion is smaller than the height of the intermediate portion and/or of the proximal portion. According to one example, the sum of the heights of the distal portion and of the intermediate portion is smaller than the height of the proximal portion. According to one example, the ratio of the height of the distal portion and the height of the proximal portion is less than 0.5, in particular less than 0.4, in particular less than 0.3, and/or greater than 0.05, in particular greater than 0.1. In some cases, the rod comprises one or several intermediate portions.
The ratio between the heights of the different portions can in particular modulate the consumption of material for the production of the rod, the demolding constraints and the mechanical performance. It is understood that a reduced section makes it possible to reduce the material required. For the same head shape, a rod whose distal end has a decreasing section will for example improve the performance in terms of hooking, but will increase the demolding constraints compared to another rod not having this characteristic and having the same head shape.
Optionally, in side view along the longitudinal direction MD and/or the transverse direction CD, the rod 30 has two opposite edges in the general shape of a tilde or an inverted tilde, or for example in the shape of an S or an inverted S.
The head 40 extends from the upper end 32 of the rod 30. The head has at least one portion extending beyond the upper end 32 of the rod 30, in order to define a hooking portion 42 or lobe adapted to engage fibers and/or loops and/or complementary retaining elements to make a self-gripping connection. The head 40 thus typically has a maximum section with a surface strictly greater than the surface of the upper end 32 of the rod 30.
The head 40 of the retaining elements 10 is typically made from a preform (not represented) resulting from molding comprising at least one rod, and optionally a head, whose upper end of the rod and/or of the head of the preform is deformed. The deformation is typically carried out by calendering, for example by hot calendering. The head 40 typically has a non-regular shape, particularly in the case where it is obtained by calendering.
The retaining device 1 according to the present invention has retaining elements with a specific geometry, which is described below.
For each rod 30, the lower end 34 is considered as being the portion of the rod 30 defining a variation in thickness of the base 10 leading to an increase in thickness. The lower end 34 of the rod 30 thus corresponds, for example, to the portion of the rod 30 that extends in a plane parallel to the plane formed by the upper face 12 of the base 10 and which is the first plane above the upper face 12 of the base 10 along the direction perpendicular to the upper face 12 of the base 10. Thus, if the upper face 12 of the base 10 is considered to be planar, the lower end 34 of the rod can for example be delimited by the variations in curvature of the upper face 12 of the base 10 upwards.
A first circle C1 is then defined within which the lower end 34 of the rod 30 is inscribed. By inscribed circle, it is meant the smallest circle that can completely surround a section considered, here the section of the rod 30 in the plane defined by the upper face 12 of the base 10 and corresponding to the lower end 34 of the rod 30. For this first circle C1, a center O1 and a diameter D1 are defined.
A second circle C2 is then defined within which the head 40 is inscribed and which is tangent to one end of the head 40 along the longitudinal direction MD. This circle thus corresponds to the smallest circle that can completely surround a projection of the head 40 in a plane parallel to the upper face 12 of the base 10 while being tangent to one end of the head 40 in the longitudinal direction. For this second circle C2, a center O2 and a diameter D2 are defined.
The end of the head 40 along the longitudinal direction MD is determined as being the point furthest from the upper end of the rod according to a side view of the retaining element considered, that is to say in view along a plane perpendicular to the transverse direction CD, or along a plane defined by the longitudinal direction MD and by an axis perpendicular to both the transverse direction CD and the longitudinal direction MD.
It should be noted here that the longitudinal direction MD and the transverse direction CD are not equivalent. In the case of a retaining device 1 whose head of the retaining elements is formed by a forming method, for example by calendering, the direction of travel of the retaining device in the tooling will influence the geometry of the head of the retaining element, and will lead to a spreading of the material along the transverse direction CD and to a packing of the material along the longitudinal direction. Thus, for example, the longitudinal direction MD can be distinguished from the transverse direction CD by the fact that the maximum dimension of the head along the transverse direction CD is greater than the maximum dimension of the head along the longitudinal direction MD.
A third circle C3 is then defined within which the upper end 32 of the rod 30 is inscribed, i.e. the smallest circle that can completely surround a considered section, here the section of the rod 30 in the plane parallel to the upper face 12 of the base 10 and corresponding to the upper end 32 of the rod 30. For this third circle C3, a center O3 and a diameter D3 are defined. When the circle C3 is not discernible from a top view of the retaining element 20, it is possible to report the dimensions observable in side view along the transverse direction CD and/or along the longitudinal direction MD in a view projected in the plane of the base 10 in comparison with the other dimensions of the lower end 34 of the rod 30 and of the head 40.
In the retaining device 1 according to the invention, the second circle C2 is comprised in the first circle C1. In other words, the first circle C1 completely surrounds the second circle C2.
Moreover, the maximum dimension of the head 40 along the longitudinal direction MD is less than 80% of the diameter D2 of the second circle C2, in some cases, the maximum dimension of the head 40 along the longitudinal direction MD is in a range whose lower bound is 30%, or 40% or 50% or 55% and/or whose upper bound is 80% or 75%.
Such a geometry of the retaining elements 20 is advantageous in several aspects. The geometry as proposed makes it possible to obtain shear characteristics at least equivalent to those of the conventional retaining elements. Moreover, such a geometry is advantageous in terms of ease of production and thus reduces the risk of obtaining dimensional drifts of the retaining elements 20, in particular by obtaining retaining elements 20 according to the invention whose material forming the heads 40 has been less deformed after demolding, in particular in comparison with the heads of the retaining elements of the prior art, for example those described in patent application EP3448194. Moreover, minimizing the deformation and therefore the displacement of material offers better reproducibility.
Optionally, the retaining elements 20 are such that the ratio between the diameter D3 of the third circle C3 and the diameter D1 of the first circle D1, that is to say the ratio between the upper end 32 of the rod 30 and the lower end 34 of the rod 30, is comprised between 0.3 and 0.75, or particularly between 0.3 and 0.65, or more particularly between 0.35 and 0.55, or even more particularly between 0.35 and 0.5. Such parameters make it possible to reduce the demolding constraints of the rod 30, while ensuring passage of the head during demolding, and minimizing the material required for the production of the retaining elements 20.
Optionally, the distance between the centers O1 and O2 measured in projection in a plane defined by the upper face 12 of the base 10 is less than 50% of the diameter D1, or less than 30%, less than 25%, less than 20%, less than 15%, or less than 10%. Optionally, the distance between the centers O1 and O2 measured in projection in a plane defined by the upper face 12 of the base 10 is greater than or equal to 0%, or greater than 0%, or greater than 1%, or greater than 4% of the diameter D1 of the first circle C1.
Optionally, the distance between the centers O1 and O2 measured in projection in a plane defined by the upper face 12 of the base 10 is less than 50% of the diameter D2, or less than 25% of the diameter D2, or more specifically less than 10% of the diameter D2. Optionally, the distance between the centers O1 and O2 measured in projection in a plane defined by the upper face 12 of the base 10 is greater than or equal to 0%, or greater than 0%, or greater than 1%, or greater than 4% of the diameter D2 of the second circle C2.
Optionally, the distance between O1 and O2 is less than 100 μm, in particular less than 75 μm, or less than 50 μm or less than 30 μm and/or greater than or equal to 0 v, or greater than 0 μm. Thus, when the retaining elements 20 cooperate with a loop counterpart, the displacement force of the head 40 is not oriented along a preferred direction but is substantially constant in multiple directions, which has the consequence of reducing the unexpected release of the loops cooperating with the retaining elements 20, for example the release of the loops along a particular stress direction. Thus, the performances in shearing and peeling are improved.
Optionally, the ratio of the diameter D2 of the circle C2 and the diameter D1 of the circle C1 is comprised between 0.3 and 0.95, or between 0.5 and 0.9, or between 0.6 and 0.85, or between 0.6 and 0.8. Such a ratio makes it possible to obtain a retaining device that can be demolded more easily, and offers a good compromise between properly demolding the retaining elements 20 and obtaining heads 40 having sufficient material to ensure satisfactory hooking performance, in particular in peeling and/or shearing, without unnecessarily increasing the amount of material required for the rod 30 and in particular the lower end 34 of the rod 30.
Optionally, the lower face 14 of the base 10 can be secured to a substrate such as a non-woven material, for example by bonding or by partial encapsulation of the woven material in the lower face 14 of the base 10.
The height H of each retaining element 20 is defined as being the maximum dimension of each retaining element 20 from the upper face 12 of the base 10 along a direction perpendicular to the upper face 12 of the base 10, i.e. a direction perpendicular to the longitudinal direction MD and to the transverse direction CD. The different heights and thicknesses defined below will also be measured along this same direction.
For each retaining element 20, the height Ht of the rod 30 is defined as being the distance between the upper face 12 of the base 10 and the upper end 32 of the rod 30. Optionally, the rod 30 has a height Ht which is comprised between 150 micrometers and 330 micrometers, particularly between 200 micrometers and 300 micrometers.
For each retaining element 20, a thickness Hh of the head 40 is defined as being the distance between the upper end 32 of the rod 30 and the upper end of the retaining element 20. The thickness Hh of the head 40 is for example comprised between 30 micrometers and 70 micrometers, particularly 40 micrometers and 60 micrometers.
Optionally, the ratio between the thickness Hh of the head 40 and the height Ht of the rod 30 is comprised between 0.05 and 0.3, or more particularly between 0.1 and 0.25. With such a ratio, the head 40 is thin enough to be easily inserted into a loop counterpart while having sufficient resistance to peeling and shearing in cooperation with a loop counterpart.
For each retaining element 20, a hooking height Ha is defined, which is the distance measured along the direction of the height between the lower end of the head 40 and the upper end of the head 40. The hooking height Ha makes it possible in particular to define a space under the head 40 in order to retain fibers and/or filaments, for example of a non-woven fabric during the application of a force. Advantageously, the size of this space is greater than the diameter of the non-woven fibers intended to cooperate with the retaining elements 20.
In the case where the hooking portions 42 or lobes 42 of the head 40 extend radially relative to the head, as for example represented in FIG. 6 , the hooking height Ha is equal to the thickness Hh of the head 40.
In the case where the hooking portions 42 or lobes 42 of the head 40 are not substantially horizontal, and are for example oriented towards the base 10 as represented schematically in FIG. 5 , then the hooking height Ha is measured as being the distance between two straight lines each parallel to the longitudinal direction MD and to the transverse direction CD, one passing through the top of the head 40, and the other passing through the lower end of the head, that is to say through the point of the hooking portion 42 or of the lobe 42 closest to the upper face 12 of the base 10 along the height direction. The hooking height Ha is then greater than the thickness Hh of the head 40.
In the device as proposed, the retaining elements 20 typically have a hooking height Ha comprised between 30 micrometers and 120 micrometers, more particularly between 30 micrometers and 70 micrometers, even more particularly between 40 micrometers and 60 micrometers. Such a hooking height makes it possible to improve the gripping and retention of counterparts such as loops.
Optionally, the ratio between the hooking height Ha and the height Ht of the rod 30 is comprised between 0.05 and 0.4, in particular between 0.05 and 0.3, more particularly between 0.1 and 0.25. A retaining element 20 which has such characteristics thus has a head 40 which is thin enough to be easily introduced into a loop counterpart while having sufficient resistance to peeling and shearing in cooperation with a loop counterpart.
The various measurements are for example carried out by an average carried out on a retaining element 20 and at least 4 adjacent retaining elements.
Optionally, the maximum dimension of the rod 30 at the lower end 34 is comprised between 110 micrometers and 900 micrometers, particularly between 350 micrometers and 550 micrometers. Thus, with such a dimension, the rod 30 is well anchored in the base 10 to ensure good rigidity of the rod when it cooperates with fibers and/or loops and/or complementary retaining elements to produce a self-gripping connection.
According to a second aspect of the invention, the retaining device 1 comprises:

- a base 10 extending along a longitudinal direction MD, having an upper face 12 and a lower face 14,
- a plurality of retaining elements 20 extending on the upper face 12 of the base 10, each retaining element 20 comprising a rod 30 surmounted by a head 40; each rod 30 comprising a lower end 34 connected to the base 10, and an opposite upper end 32 from which the head 40 extends, wherein, for each retaining element 20, in projection in a plane formed by the upper face 12 of the base 10:
- the lower end 34 of the rod 30 is inscribed within a first circle C1 with center O1,
- the head 40 is inscribed within a second circle C2 with center O2 and diameter D2, said second circle C2 being the smallest circle comprising the head 40, which second circle C2 is typically tangent to one end of the head 40 along the longitudinal direction MD and/or the transverse direction CD,
- wherein
- the minimum distance between the respective edges of two first circles C1 of two lower ends 34 of adjacent rods 30 is at least greater than 50 micrometers, particularly greater than 70 microns, more particularly greater than 90 microns and/or less than 300 microns, less than 250 microns, more particularly less than 200 microns, and/or
- in projection in a plane formed by the upper face 12 of the base 10, in a representative area with retaining elements 20, the occupancy rate of the first circles C1 of the retaining elements 20 in said representative area is between 25% and 80%, particularly between 40% and 80%, in particular between 50% and 70%.

By adjacent, it is meant successive retaining elements along the same line formed by the retaining elements 20 on the upper face 12 of the base 10, or the closest retaining elements 20 belonging to two successive lines.
By representative area, it is understood here an area comprising a plurality of elementary repeat patterns, for example between 5 and 10 patterns, typically 6 or 7 patterns. This area is typically observed from a photo obtained with a digital microscope from the company Keyence Corporation under the reference “VHX 6000”, at a magnification X100 and the measurements are obtained with the image analysis software of the digital microscope.
Thus, with such an arrangement, the space between the lower ends 34 of the rods 30 of the retaining elements 20 and/or the occupancy rate of the lower ends 34 of the rods 30 of the retaining elements 20 is sufficient to allow the base 10 to remain flexible while having peeling and shearing performances equivalent to those of the prior products, or even improved in peeling due to the improved flexibility of the retaining device 1. Thus, the base 10 is sufficiently flexible to be able to be rolled up in the form of a roll in order to be transportable while having acceptable peeling and shearing performance, without consuming too much material. In addition, with such an occupancy rate, it is possible to obtain good flexibility of the retaining device 1, in particular when it is arranged for hygiene applications, for example for absorbent articles, in particular open or closed diapers. Previous products with a geometry such that the first circle C1 was comprised in the second circle C2 or in which only part of the second circle C2 was inscribed within the first circle C1 did not have such issues, but nevertheless presented issues as mentioned in the preamble, in particular in terms of material consumption and user's feeling.
According to another example, the flexibility of the base 10 is improved with a base 10 whose thickness is comprised between 10 μm and 100 μm, in particular between 15 μm and 65 μm, particularly between 16 μm and 65 μm, or between 22 μm and 49 μm.
According to another example, the flexibility of the base 10 is further improved for a base 10 whose grammage is comprised between 15 g/m²and 120 g/m², in particular between 20 g/m²and 90 g/m², in some cases between 26 g/m²and 70 g/m².
These different characteristics combine with a synergy effect to improve the flexibility of the base 10.
The non-woven material then has, for example, a grammage of less than 80 g/m², in some cases, comprised between 5 and 120 g/m², between 10 and 70 g/m².
Optionally, the third circle C3 is comprised in the second circle C2.
Typically, each retaining element 20 according to the invention has a general shape in a side view along the longitudinal direction MD which is different from or similar to the general shape of this same retaining element 20 in a side view along the transverse direction CD. Typically, each retaining element 20 according to the invention having a rod 30, which rod 30 has a general shape in a side view along the longitudinal direction MD which is different from or similar to the general shape of this same rod 30 in a side view along the transverse direction CD. Typically, each retaining element 20 according to the invention having a head 40, which head 40 has a general shape in a side view along the longitudinal direction MD which is different from or similar to the general shape of this same head 40 in a side view along the transverse direction CD. According to one example, FIG. 4 and FIG. 5 correspond to the same retaining element 20 in a view along the transverse direction CD and respectively in a view along the longitudinal direction MD or FIG. 4 and FIG. 6 correspond to the same retaining element 20 in a view along the transverse direction CD and respectively in a view along the longitudinal direction MD.
Optionally, the number of retaining elements 20 per unit area is less than 600 retaining elements 20 per cm²and particularly is comprised between 160 and 340 retaining elements 20 per cm².
In the present application, the heights and thicknesses are typically observed from a photo obtained with a digital microscope from the company Keyence Corporation under the reference “VHX 6000”, at a suitable magnification, for example a magnification of X500 as is the case of FIG. 2 , and the measurements are obtained with the image analysis software of the digital microscope.
Generally, it is possible to distinguish two types of self-gripping connections, those whose retaining elements cooperate with other retaining elements of the same types/natures or in the form of fibers and/or filaments and/or loops to make mechanical connections and those whose retaining elements cooperate with surfaces to make adhesive-type connections (Gecko) or using Van der Waals forces. Although this second type of connection can be considered in some cases as a connection called self-gripping connection, such retaining elements using Van der Waal forces have a behavior and properties totally different from those using mechanical connections. Indeed, in the case of the retaining elements using Van der Waal forces, only the upper faces of the heads ensure the fixing with the receiving surface whereas in the case of the retaining elements for a mechanical fixing, the fixing is not ensured by the upper face of the heads but by the lower face of the head and of the rod. According to one example, the device according to the invention is only suitable for making mechanical connections.
Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. Particularly, individual characteristics of the different illustrated/mentioned embodiments can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.
It is also obvious that all the characteristics described with reference to one method are transposable, alone or in combination, to one device, in particular between the different aspects of the invention which are presented, and conversely, all the characteristics described with reference to one device are transposable, alone or in combination, to one method.

Claims

1. A retaining device comprising:

a base extending along a longitudinal direction, having an upper face and a lower face,

a plurality of retaining elements extending on the upper face of the base, each retaining element comprising a rod surmounted by a head; each rod comprising a lower end connected to the base, and an opposite upper end from which the head extends,

wherein, for each retaining element, in projection in a plane formed by the upper face of the base:

the lower end of the rod is inscribed within a first circle C1 with center O1, the head is inscribed within a second circle C2 with center O2 and diameter D2, said second circle being the smallest circle comprising the head, which second circle C2 being tangent to one end of the head along the longitudinal direction and/or the transverse direction,

such that:

the maximum dimension of the head passing through the center O2 of the circle C2 and extending along the longitudinal direction and/or the transverse direction is less than 80% of the diameter D2 of the second circle C2.

2. The retaining device according to claim 1, wherein the second circle C2 is comprised in the first circle C1.

3. The retaining device according to any of claim 1, wherein, the first circle C1 having a diameter D1, the distance between O1 and O2 is less than or equal to 50% of the diameter D1 of the first circle C1, in particular less than 30%, less than 25%, less than 20%, less than 15%, or less than 10%, and optionally, the distance between O1 and O2 is greater than or equal to 0% of the diameter D1 of the first circle C1, or greater than 0%, or greater than 1%, or greater than 4%.

4. The retaining device according to claim 1, wherein the distance between O1 and O2 is less than or equal to 50% of the diameter D2 of the second circle C2, in particular less than 30%, less than 25%, less than 20%, less than 15%, less than 12%, or less than 10% and optionally, the distance between O1 and O2 is greater than or equal to 0% of the diameter D2 of the second circle C2, or greater than 0%, or greater than 1%, or greater than 4%.

5. The retaining device according to claim 1, wherein the distance between O1 and O2 is less than or equal to 100 μm, in particular less than or equal to 75 μm, less than or equal to 50 μm or less than or equal to 30 μm.

6. The retaining device according to claim 1, wherein the upper end of the rod is inscribed within a third circle C3, said circle C3 being comprised in the second circle C2.

7. The retaining device according to claim 1, wherein a non-woven material is secured to the lower face of the base.

8. The retaining device according to claim 1, wherein the ratio of the diameter D2 of the circle C2 and the diameter D1 of the circle C1 is comprised between 0.3 and 0.95 or more specifically between 0.5 and 0.9.

9. The retaining device according to claim 1, wherein the retaining elements have a hooking height comprised between 30 micrometers and 120 micrometers, more particularly between 30 micrometers and 70 micrometers, even more particularly between 40 micrometers and 60 micrometers.

10. The retaining device according to claim 1, wherein the head has a thickness comprised between 30 micrometers and 70 micrometers, particularly 40 micrometers and 60 micrometers.

11. The retaining device according to claim 1, wherein the rod has a height which is comprised between 150 micrometers and 330 micrometers, particularly between 200 micrometers and 300 micrometers.

12. The retaining device according to claim 1, wherein the ratio of the thickness of the head and the height of the rod is comprised between 0.05 and 0.3, or more particularly between 0.1 and 0.25.

13. The retaining device according to claim 1, wherein the ratio of the hooking height and the height of the rod is comprised between 0.05 and 0.4, particularly between 0.05 and 0.3, more particularly between 0.1 and 0.25.

14. The retaining device according to claim 1, wherein the rod has, in side view along the longitudinal direction and/or the transverse direction, a proximal portion extending from the lower end, a distal portion extending from the upper end and an intermediate portion arranged between the proximal portion and the distal portion, the distal portion and the proximal portion have, with respect to a straight line perpendicular to the longitudinal direction and to the transverse direction, a curvature greater than the curvature of the intermediate portion.

15. The retaining device according to claim 14, wherein, in side view along the longitudinal direction and/or the transverse direction in a view projected in the plane perpendicular to this side view, the rod has two opposite edges of which at least one, in some cases both edges, has a general shape of a tilde or an inverted tilde, or a shape of an S or an inverted S.

16. The retaining device according to claim 1, wherein, in side view along the longitudinal direction and/or the transverse direction, said retaining device has a ratio between the dimension of the upper end of the rod and the dimension of the lower end of the rod comprised between 0.3 and 0.75, or particularly between 0.3 and 0.65, or more particularly between 0.35 and 0.55, or even more particularly between 0.35 and 0.5.