Looped layer or strip including differential attachment areas and nappy comprising such a layer

Abstract

The invention relates to a looped layer in the form of a laminate including an inner supporting element (1), for example a non-woven fabric or a plastic film, and a plurality of fibres and/or filaments (3) attached to the outer surface of the supporting element so as to form loops for engaging with hooks, the attachment being carried out in a attachment region, while in at least one other so-called looped region the filaments and/or fibres are not attached to the supporting element so as to form loops, characterised in that at least in one area (5) of at least one attachment region the attachment is only carried out in a partial manner, while at least in one other area (4) of at least one attachment region the attachment is carried out in a complete manner.

Claims

1. A looped layer in the form of a laminate comprising an internal support element (1), formed by at least one non-woven fabric, and a plurality of fibers and/or filaments (3) secured to an external face of the support element so as to form loops for engaging with hooks, said plurality of fibers and/or filaments (3) being secured to said external face in at least one attachment region, while in at least one other so-called looped region the filaments and/or fibers are not secured to the support element so as to thus form loops, characterized in that in at least one zone (5) of the at least one attachment region said plurality of fibers and/or filaments (3) are secured in a partial manner to said external face, while in at least one other zone (4) of the at least one attachment region said plurality of fibers and/or filaments (3) are secured to said external face in a complete manner.

2. The layer according to claim 1, characterized in that said plurality of fibers and/or filaments (3) are secured to said external face in both said at least one zone and said at least one other zone by welding.

3. The layer according to claim 2, characterized in that it exhibits a weld differential greater than 1.5.

4. The layer according to claim 1, characterized in that the plurality of fibers and/or filaments (3) forming the loops (7) are consolidated into at least one non-woven fabric.

5. The layer according to claim 1, characterized in that at least one layer of printing ink intended to form a pattern or patterns or designs is deposited onto the support element (1).

6. The layer according to claim 5, characterized in that said at least one zone and said at least one other zone alternate both in a CD direction along a given strip and in the MD direction of a strip to an adjacent strip.

7. The layer according to claim 1, characterized in that the at least one attachment region is/are made in the form of strips extending in a CD direction of the laminate, said at least one zone and said at least one other zones being produced alternately along a strip in the CD direction.

8. The layer according to claim 1, characterized in that said at least one other zone are made alternately in a MD direction of a strip to an adjacent strip.

9. The layer according to claim 1, characterized in that said at least one zone and said at least one other zone are made in the form of a semi-circle of which the diameter is contiguous to a looped region.

10. The layer according to claim 1, characterized in that said plurality of fibers and/or filaments (3) are secured to said external face in both said at least one zone and said at least one other zone by calendaring.

11. The layer according to claim 1, characterized in that the at least one attachment region is/are made in the form of strips extending in a CD direction of the laminate parallel to one another, said at least one zone and said at least one other zone being produced alternatively along a strip in the CD direction.

12. A diaper comprising a layer according to claim 1.

13. A diaper according to claim 11, characterized in that the layer forms a landing zone of the diaper.

14. A self-fastening closure system comprising on the one hand a loop element comprising a layer according to claim 1 and on the other hand a hook element, the hooks of which are arranged to be able to engage in the loops in order to provide the closure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following embodiments are described purely as an illustration and referring to the drawings in which:

(2) FIGS. 1 and 1B are diagrams in longitudinal section of a laminate according to the invention illustrating the principle of the invention, FIG. 1A showing the state when a hook is introduced into a loop, while FIG. 1B shows the state once the hook has applied normal upwards traction;

(3) FIG. 1C is a more detailed side view of the laminate of FIG. 1A, without the hook;

(4) FIGS. 2A, 2B, 2C, 2D, 2E and 2F show diagrammatically laminates according to the invention in perspective according to various embodiments;

(5) FIG. 2G shows diagrammatically a laminate according to the invention in order to illustrate the concept of side effect zone of the zones with a partial weld, a side effect that should be taken into account in particular when assessing the volume fraction of a partial weld zone by removing these side effect zones of the measurement zone;

(6) FIG. 2H shows diagrammatically a laminate similar to the one in FIG. 2F in which the measurement zones of the volume fraction or compactness have been shown;

(7) FIG. 3A is a photograph seen from above with a microscope (50 enlargement) of a circular zone of a laminate comprising a complete weld zone (in the middle) between two regions with loops (on the left and on the right of the figure);

(8) FIG. 3B is a view on a scale four times greater (200 enlargement) of the circled part of the complete weld zone of FIG. 3A;

(9) FIG. 4A is a photograph seen from above with a microscope (50 enlargement) of a circular zone of a laminate comprising a partial weld zone (in the middle) between two regions with loops (on the left and on the right of the figure);

(10) FIG. 4B is a view on a scale four times greater (200 enlargement) of the circled part of the partial weld zone of FIG. 4A; and

(11) FIGS. 5 and 6 are views in diagrammatic form of a cross-section obtained by software when measuring the volume fraction, respectively for the weld zones of FIGS. 3B and 4B.

DETAILED DESCRIPTION OF EMBODIMENTS

(12) FIGS. 1A and 1B show a laminate according to the invention. The laminate comprises a base element in the form of a non-woven fabric 1 that has a lower face in the figure corresponding to the internal face intended to be located on the side of the body of the user of the diaper in a case where it is used as a landing zone and which comprises on its opposite face, which is the upper face in the figure, and so external with respect to the body of the user of the diaper, printed patterns intended to be seen from the outside and filaments and/or fibers 3 forming loops being secured by welding in weld regions 4, 5 to the non-woven fabric 1.

(13) In FIGS. 1A and 1B, filaments and/or fibers 3 are shown diagrammatically and form in reality a network of filaments and/or fibers as shown in FIG. 1C.

(14) In FIGS. 1A and 1B, which are diagrammatic sectional views, one can see that the weld regions comprise two different types of weld, namely complete weld zones 4 extending in the length direction, i.e. perpendicular to the figure and which are shown by cross-hatched lines, and partial weld zones 5 which are shown by hatched lines. The laminate thus produces loops which can engage with hooks in order to provide attachment by means of a self-fastening hook and loop system, in particular for a diaper, the laminate being disposed in the central zone of the front part of the diaper on the belt, while the hooks emanate from legs disposed at the lateral ends of the rear part of the diaper, also on the belt. However, it should be noted that without straying from the framework of the invention, one could make provision for the laminate with loops to be disposed in the rear part and for the hooks to be disposed in the central part of the belt of the front part of the diaper.

(15) Loops are understood to mean a filament and/or a fiber that comprises two ends, each one joined to the support at a respective point of the support or at a same point of the support. A loop can also be formed from a number of filaments or fibers that are joined to one another and of which at least two are joined to the support at one point or at two respective distinct points.

(16) The two partial and complete weld zones are therefore different, and in particular the partial weld zone can detach from the supporting non-woven fabric 1 by the action of a traction force of a hook 6 that penetrates into an adjacent loop of a partial weld zone 5. One thus arrives at the situation shown in FIG. 1B. As can be seen, the complete weld zones 4 have not been separated from the non-woven fabric 1 by the action of the hook 6. On the other hand, the partial weld zone 5 has detached from the non-woven fabric 1 by the action of the hook 6 and one now thus obtains a loop with greater dimensions made up of two filaments 3 and of the zone 5 which also comprises the continuity of the same filaments.

(17) Obviously, this effect is obtained for a so-called normal traction force of the hook. If one applies a very high traction force, the arrangement is such that the filaments break before the complete welds. For a normal traction corresponding to a traction exerted by a person with normal strength using a diaper in the normal way, the partial weld 5 will give way before the filaments 3 break and will thus produce a large loop.

(18) In particular, in order to define whether this is a partial weld or a complete weld, one notes the volume fraction of the material contained in the weld zone that one wishes to assess. A complete weld is considered to be a weld of which the molecules of the filaments and/or fibers have been completely mixed so as to lose their dimensional integrity, and this is manifested by a passage, at the level where the weld is made, of a pile of fibers in the case of a partial weld to a mass of compact material in the case of a complete weld.

(19) A partial weld zone will have great porosity to air, to liquid or the like and a volume fraction or compactness well below 100% and in particular well below that of a complete weld zone of which the volume fraction is close to 100%.

(20) In the example of FIGS. 1A and 1B, the user makes the hooks penetrate into the loops so as to ensure that the diaper is sealed. Upon opening, the user pulls the hook zone towards him or her and thus exerts a force greater than the force required to disconnect the partial welds from the support. Thus, the loops are enlarged and enable one to obtain a normal opening force greater than a similar laminate comprising purely complete welds 3 and 4. For example, one obtains here an opening force measured at 4.5 N for a laminate only with complete welds, and 5.5 N for the laminate with a double complete and partial weld.

(21) In particular, the respectively complete and partial welds are made differently and in particular with a different calendering pressure. In order to do this, in particular one can either produce patterns on the calendering rollers which are different depending upon whether one wishes to produce a complete calendering zone or a partial calendering zone. One can also provide two calendering rollers in succession, one for implementing first partial calendering with a low calendering force on all of the weld zones and then a second calendering roller in order to finish the complete calendering in the zones where one wishes the calendering to be complete, while the partial calendering zones are not affected by the second calendering roller. It should be noted that the opposite of these steps is also possible, and that the calendering zones of the first step are not affected by the second calendering roller.

(22) One can also initially calender the web of fibers and/or filaments and then calender this web on the support. The previously calendered zones of the web then create partial attachment zones when they are calendered on the support, the pressure applied to the previous weld zone during assembly being lower.

(23) In particular in order to determine whether a calendering zone is a partial calendering zone or a complete calendering zone, X-ray scanning of the weld zone is implemented in order to recreate the volume of material contained on the basis of different cross-sections.

(24) FIGS. 2A, 2B, 2C, 2D, 2E, 2F and 2G show various possible embodiments for producing the laminate with loops with differential welds according to the principle of the invention.

(25) Thus, in FIG. 2A the weld regions form strips extending in the CD direction alternating with zones in which the filaments are not welded to form loops with respect to the support element 1. Furthermore, as shown in the figures, in each weld attachment region in the form of a strip, complete weld zones 4 alternate with partial weld zones 5 in the CD direction. As shown, each zone has substantially the same longitudinal extension in the CD direction, but other configurations could be envisaged, for example partial zones in the form of a circular disc or in any other form, identical to one another or not, spaced apart from one another being surrounded by a complete weld zone, or spaced apart from the complete weld zone and isolated from the latter.

(26) According to another embodiment shown in FIG. 2B, the alternation in the CD direction is supplemented by an alternation in the MD direction so as to thus form a sort of checkerboard between the partial and the complete weld zones.

(27) According to another embodiment shown in FIG. 2C, the strips of partial and complete welds are continued in the CD direction, but alternate with one another in the MD direction.

(28) FIG. 2D shows another embodiment in which the complete weld strips have a greater width than partial weld strips formed alternately with the complete weld strips, the weld strips extending in the CD direction. In particular, the partial weld strips are thin, in particular to the point of being substantially in the form of a single weld line.

(29) FIG. 2E shows an embodiment substantially identical to that of FIG. 2D, the only difference being that the partial weld lines are, furthermore, discontinuous in the CD direction.

(30) FIG. 2F shows an embodiment in which the partial weld zones are produced in the form of rows of zones in a semi-circle, spaced apart from one another in the CD direction, the rows of semi-circles preferably being, moreover, offset from one another from one row to the next, for example by a half distance between two successive semi-circles of a same row. Furthermore, the line forming the diameter of the semi-circle of a row is located on the side of the looped zones. In particular, as shown in the figure, the concavities of the semi-circles are orientated in opposite directions from one row to the next row.

(31) FIG. 2H shows an embodiment similar to that of FIG. 2F in which the zones for measuring the volume fraction or compactness were shown. The measurement zones are indicated by substantially circular shapes with cross-hatching, respectively in the partial weld zone in the form of a half disc and in the complete weld zone.

(32) FIG. 2G shows an embodiment in which two rows of loops are separated by a weld zone. The weld zone comprises a region in the form of a central complete weld strip (extending longitudinally in the CD direction), between two lateral partial weld zones, each separating the central complete weld strip of a respective row of loops. In each of the lateral partial weld zones a so-called side effect strip is moreover defined in which the weld is neither complete nor truly partial and corresponds to side effects that appear during calendering of the complete zone and partial zones respectively. The partial weld zone extends beyond these side effect zones, and to the contiguous row of loops.

(33) When measuring the volume fraction one can, for the partial weld zones, take into account these side effect zones by removing them from the measured zone. One can do this in all of the embodiments described here, and also generally for any other similar embodiment.

(34) In the different embodiments shown above fibers and/or filaments (these two terms are used in the present application in an equivalent and interchangeable manner) have been shown which are not consolidated with one another. However, one could also make provision to use consolidated filaments together in a non-woven fabric and make the respectively partial and complete welds on this non-woven fabric.

(35) In the present application non-woven fabric means a product obtained at the end of the formation of a layer of fibers and/or filaments which have been consolidated. The consolidation can be mechanical, chemical or thermal and is manifested by the presence of connections between the fibers and/or the filaments. This consolidation can be direct, i.e. made directly between the fibers and/or filaments by welding, or it can be indirect, i.e. by means of an intermediate layer between the fibers and/or the filaments, for example a layer of adhesive or a layer of binder. The term non-woven relates to a structure in the form of a layer or strip of fibers and/or filaments which are interlaced in a non-uniform, irregular or random manner. A non-woven fabric can have a single layer structure or a multiple layer structure. A non-woven fabric can also be joined to another material such as a film in order to form a laminate. A non-woven fabric can be made from different synthetic and/or natural materials. The natural materials are, for example, cellulose fibers such as cotton, jute or paper pulp and the like, and can also include reprocessed cellulose fibers such as rayon or viscose. The natural fibers for a non-woven fabric can be prepared by using various processes such as carding. Synthetic materials include, but are not restricted to, for example, synthetic thermoplastic polymers which are known to form fibers that include, but are not restricted to, polyolefins, for example polyethyelene, polypropylene, polybutylene and the like; polyamide, for example polyamide 6, polyamide 6.6, polyamide 10, polyamide 12 and the like; polyesters, for example polyethylene teraphthalates, polybutylene terephthalates, polylactic acids and the like, polycarbonates, polystyrenes, thermoplastic elastomers, polymer vinyls, polyurethanes and mixtures and copolymers of the latter.

(36) FIGS. 3A, 3B, 4A, 4B, 5 and 6 show in a top view (3A, 3B, 4A, 4B) or in cross-section (5, 6), respectively in the form of photographs and of diagrams of the parts of a non-woven fabric with loops in which complete calendering zones (FIGS. 3A, 3B and 6) and partial calendering zones (FIGS. 4A, 4B and 5) have been formed.

(37) In the complete calendering zonesthe zone delimited by the circle C in FIG. 3A and shown in FIG. 3Bthe majority of the fibers and/or filaments have been crushed and cannot be differentiated from one another, such that the zone is mainly covered by an opaque field. In this zone the fibers have been greatly flattened. As can be seen in the cross-section in FIG. 5, the volume fraction is high, very little empty space remaining in the material of the fibers that have been welded together.

(38) In the partial calendering zones, in particular the zone delimited by the circle B in FIG. 4A and shown in FIG. 4B, the majority of the fibers and/or filaments have only been slightly crushed and can be differentiated from one another. As can be seen in the cross-section in FIG. 6, the volume fraction is smaller than in FIG. 5, an empty space (i.e. without any material) that is not negligible remaining in the material of the fibers that have been welded together.

(39) Different materials could be used for the fibers and/or filaments intended to be welded or attached completely and for the fibers and/or filaments intended to be welded or attached partially.

(40) For a laminate, the MD direction (Machine Direction) is the direction in which the laminate is unrolled when it is produced and the CD direction (Cross Direction) is the direction perpendicular to the MD direction in the plane of the laminate.

(41) According to one embodiment of the invention, one could envisage more than two types of weld, for example three types of weld.

(42) According to embodiments, one could envisage different partial welds by varying their dimensions, their form, their volume fraction, thus making it possible to obtain the required performance for each type of application.

(43) A product with alternating partial welds and complete welds in CD of the type of FIG. 2A makes it possible to obtain an increase of approximately 10% of the peel away performance with respect to the prior art. On thus obtains an average peel away force of 4.1 N as opposed to 3.7 N for a product made purely with complete welds.

(44) Non-woven fabric with loops means a non-woven fabric that forms loops after being joined to the support.

(45) In general, the fibers and the filaments differ mainly by their length and by their production method.

(46) Filaments mean the unitary elements, with very great lengths with respect to the diameter to which their section is assigned, extruded continuously in order to directly form a strip of non-woven fabric that can then be consolidated by thermo-linking or any other means so as to make it possible to achieve the desired performance and/or their transportation. Preferably the filaments exhibit a length greater than 120 mm.

(47) Fiber is understood to be the generic term designating a textile material or a textile material element with reduced length less than the length of the filaments and able to be spun and/or used in the production of non-woven fabrics. A distinction can be made between two types of fiberthe short fibers formed discontinuously with a small length of less than 70 mm (preferably 25 mm to 60 mm) and the long fibers formed discontinuously with a large length of greater than 70 mm (preferably 80 mm to 120 mm).

(48) Unlike filaments that are consolidated directly after having been extruded, fibers are generally aligned and organized in a layer during a carding step that is well known to the person skilled in the art. This layer can then be consolidated by thermal linking or by any other means so as to make it possible to achieve the desired performance and/or their transportation.