MALE-FEMALE TYPE, MULTI-LAYER FEMALE MATERIAL TO BE USED IN A MECHANICAL REVERSIBLE TEAR-OFF CLOSING DEVICE AND METHOD TO PRODUCE SAID MULTI-LAYER FEMALE MATERIAL" DESCRIPTION

Technical Field

The present invention relates to the field of closing devices for hygienic products or disposable garments. More in particular, the object of the invention is a mechanical reversible tear-off closing device of the male-female (hook/loop) type, a multilayer female material (loop) to be used in a mechanical reversible tear-off closing/opening device and a method to produce said multilayer female material.

State of the Art

The mechanical closing/opening devices of the hook-and-loop type (also called simply male-and-female) are closing systems constituted by two components: the female part, also called loop material or frontal tape (and also female material), having parts with filaments forming loops; and the male part, usually constituted by hooks produced by means of extrusion and available in different shapes, for example single hook, double hook or mushroom-type.

Application examples comprise absorbent hygienic products, like baby or adult diapers, disposable garments for surgery and the like.

Devices are also known, with a first closing end formed by adhesive tape and a second end formed by a film, to which the adhesive end is attached and from which is removed. However, this closing device is less and less used, in favor of the hook-and-loop type.

One of the features required for the female part (or loop or frontal tape) of these closing devices is the fact of being made of soft materials, pleasant to the touch. Usually, one of the most used material is nonwoven fabric, as it allows to have closing systems that are soft, aesthetically pleasant (for instance printed or embossed), at low cost and providing good performance, even if for a limited number of uses.

The currently known methods for producing frontal tapes consist in laminating a support layer, or backing layer, that gives dimension stability to the material, with an upper layer, from which turns or loops project.

The loops can be originated by continuous filaments (see for instance the patent applications WO2012121875A1 and US8347466B2) or by discontinuous fibers differently joined (see for example the patent application EP2636782A1 ) The typical materials used as backing layer are films, spunbonded nonwovens or SMS (spunbonded/meltblow/spunbonded) nonwoven fabrics.

The materials used for the loop layers use filaments of polyamide, polypropylene, or nonwoven fabric carded and then joined by means of thermal bonding or through-air bonding.

The bond strength of the hook-and-loop fasteners depends on both the probability that the hook engages a loop and the strength required for reopening the coupling. The reopening of the hook-and-loop mechanical fasteners can be caused by the following: removal of the hook from the loops (that is more frequent with simple hooks, less frequent with mushroom-type hooks), breakage of the fiber or filament because of the stress imparted by the hook, or detachment of single fibers from the nonwoven fabric (the so-called hairing). Object and summary of the invention

An object of the invention is to provide a reversible tear-off closing/opening device comprising a male part suitable to couple to a respective female part, whose tear strength is greater than that of known devices.

A further important object of the invention is to provide a female part for a reversible tear-off closing/opening device, that can be used with different male parts, always ensuring a tear strength greater than that of known devices.

This and other objects, that will be clearer below, are achieved by means of a reversible tear-off closing/opening device comprising a male part designed to couple to a respective female part; the mal part comprises a plurality of appendices with attaching heads; the female part comprises a support layer and a fibrous structure provided on the support layer for receiving the attaching heads; the device is characterized in that the fibrous structure comprises

- a first fibrous layer above the support layer, provided with first fibers; the first layer is provided with a first value of average titre of the fibers, the interstices between the first fibers define spaces for receiving the attaching heads of the male part of the device;

- a second fibrous layer above the first fibrous layer, provided with second fibers and interspaces between the second fibers, the second fibrous layer having at least two status, a not-deformed rest status and a reversibly deformed status, the second fibrous layer having a second value of average titre of fibers that is lower than the first value of average titre, so that the interspaces between the second fibers are, in the rest status, not dimensionally suitable to receive the attaching heads (for example, generally speaking it is possible to state that the interspaces between the second fibers have, in the rest status, smaller dimensions than the dimensions of the attaching heads, while the interspaces between the second fibers have, in the reversibly deformed status, dimensions equal to or greater than those of the attaching heads; clearly, the interspaces, being formed by a partially random distribution of fibers, even if regularity characteristics, are not all identical and have variable dimensions; therefore, the term "dimensions" of the interspaces in this context refers to the average dimensions),

the attaching heads, when coupling the male part to the female part, being forced to cross the second fibrous layer; when coupling the male part to the female part, the second fibrous layer being suitable to pass from the not- deformed rest status to the reversibly deformed status, allowing the attaching heads to enter the first fibrous layer and to be received in the receiving spaces; when the attaching heads are housed in the first layer, the second fibrous layer has returned into the substantially not-deformed status and prevents the attaching heads from exiting from the housing seats.

According to the known technique, "titre" is the linear mass density of a fiber or yarn, i.e. the measurement of the mass per unit of length. The unit of measurement of linear mass density is tex, corresponding to a gram per kilometer. An even more common unit of measurement is the submultiple decitex or dtex, i.e. the tenth part of a tex, corresponding to a gram per 10 kilometers of fiber or yarn. Another unit of measurement for the linear mass density is denier, or den D, i.e. the mass in grams per 9 kilometers of fiber or yarn. Practically, 1 den corresponds to 1 .1 dtex.

For fiber numbering, the gravimetric method (by weighting) can be used, wherein the weight of a quantity of fiber, whose cumulative length has been measured, is determined by means of an analytical balance (0.1 mg readability). For example, 1 ,000 baves of 60 mm length are taken and then weighed by means of the balance; the number is then divided for the length of 60 m (0.06 km), deriving from 100 fiber x 60 mm.

Other faster methods for measuring the fiber titre provide for the use of instrumental techniques standardized with respect to the gravimetric technique described above.

For instance, the Vibroskop instrument by Lenzing Instruments AG provides that a single fiber of unknown titre is positioned between two vibroclips and set into natural vibration by an electronic impulse. The titre is derived from the fiber's vibration frequency.

Both the gravimetric and the vibroscope technique are described in the international standard ISO 1973:1995 "Textile fibers -- Determination of linear density - Gravimetric method and vibroscope method". The gravimetric method and the vibroscope method essentially give the same result, and are considered equivalent in the present description. The values of titre according to the present invention independently refer to one of these techniques.

The average titre (or average denier) of a nonwoven material is defined as the weighted average of the titre of the fibers constituting the material. For example, let's take into account the following examples.

- Material produced by mixing 50% wt. of 2 dtex fibers and 50% wt. of 6 dtex fibers: the average titre corresponds to (2x50+6x50)/100 dtex, that is 4 dtex.

- Material produced by mixing 80% wt. of 2 dtex fibers and 20% wt. of 6 dtex fibers: the average titre corresponds to (2x80+6x20)/100 dtex, that is 2.8 dtex.

- Material produced by mixing 2 dtex fibers (70%), 6 dtex fibers (20%), 3 dtex fibers (10%): the average titre corresponds to (2x70+6x20+3x10)/100 dtex, i.e. 2.9 dtex.

- Material produced with fibers A (30%) and fibers B (70%) having the same titre (3 dtex): the average titre corresponds to the common titre of the fibers (3x70 + 3x30)/100, i.e. 3 dtex.

- Material produced with a single 3 dtex fiber A (100%): the average titre (3x100 + 0x0)/100 is, obviously, the titre of the 3 dtex fiber.

Therefore, "average titre" of a mix of fibers means the titre, both in case this mix is composed of fibers of different titres and in case the mix is composed of fibers of only one titre. Practically, the present invention provides for a composite female material, or loop material, obtained through joining, for instance by laminating, a support layer, or backing layer (for instance in film or spunbonded or SMS of grammage comprised for example between 5 and 25 g/m ² ) and a fibrous structure with at least two layers (for instance a carded nonwoven fabric of grammage comprised between 25 and 50 g/m ² ) characterized by the "asymmetrical" nature of the fiber composition of the two layers; in particular, the fibrous structure, for instance a carded nonwoven, joined by means of through-air bonding or thermal bonding processes, has a second exposed layer formed by fiber with low denier (for instance average titre of the fibers comprised between 1 .5 dtex and 3.3 dtex), giving softness and pleasure to the touch, and a first layer, into contact with the backing layer, constituted by fibers with significantly higher denier (for instance, average titre of the fibers comprised between 4.4 dtex and 10.0 dtex), generating a significantly more open structure with more hollow spaces between the fibers. The asymmetrical fibrous structure is then joined to the backing layer, preferably thermally (for instance laminated through welding calender or ultrasounds; during this step, through a cylinder with engraving of adequate pattern two joining or bonding areas are generated between the two materials).

The loop material obtained with an "asymmetrical" fibrous structure reproduces, on reduced scale, the operation mechanism of buttons and buttonholes: in fact, under the pressure exerted by the user during the coupling step, the hooks, provided preferably with mushroom-type heads, pass through the closer layer of the asymmetrical material, achieving the more open layer, where the head of the hooks has enough space to relax, thus remaining trapped therein.

Preferably, according to the invention the ratio between the value of average titre of the first fibers and the value of average titre of the second fibers is greater than or equal to 2, more preferably comprised between 2 and 5.

Preferably, the second value of average titre of the second fibers is comprised between 1 .1 dtex and 4.4 dtex and the first value of average titre of the first fibers is comprised between 4.4 dtex and 13 dtex.

According to preferred embodiments, the fibrous structure comprises a multi-layer nonwoven fabric.

The layers of the multi-layer nonwoven fabric are preferably formed by cut crimped fibers.

Preferably, the layers of the nonwoven fabric are joined together, preferably by means of thermal bonding or through-air bonding or by using adhesive resin.

According to preferred embodiments, the fibers of these layers comprise thermoplastic fibers.

According to preferred embodiments, the fibrous structure is formed by a nonwoven fabric with a weight comprised between 20 and 50 g/m ² . According to preferred embodiments, the first fibrous layer is comprised between 60% and 80% of the overall thickness of the fibrous structure.

According to preferred embodiments, the second fibrous layer is comprised between 20% and 40% of the overall thickness of the fibrous structure.

According to preferred embodiments, the weight of the first fibrous layer is comprised between 50% and 75% of the overall weight of the fibrous structure.

According to preferred embodiments, the weight of the second fibrous layer is comprised between 25% and 50% of the overall weight of the fibrous structure.

According to preferred embodiments, the fibrous structure is joined to the support layer in bonding areas, where the thickness of said fibrous structure is lower.

Preferably, in the bonding areas the fibrous structure is joined to the support layer by means of at least partial fusion of its fibers on the support layer.

Preferably, at least part of the bonding areas are strips extending continuously between two opposite ends of the border of the female part.

According to preferred embodiments, the fibers of the fibrous structure are of the thermoplastic type.

According to preferred embodiments, the fibers of the fibrous structure comprise one or more of the following: polyesters, polyolefins, polyamides and combinations or bicomponent structures thereof. Preferably the polyesters comprise PET, PBT, polyester copolymers, mixtures thereof; polyolefins comprise polyethylene (PE), polypropylene (PP), polybutene (PB), copolymers and mixtures thereof; bicomponent fibers comprise both concentric core/sheath structures and eccentric structures or side-by-side structures.

According to preferred embodiments, the support layer is realized by at least one film, at least one fabric, at least one nonwoven fabric, or a combination thereof. Preferably, at least one nonwoven fabric is of the spunbonded, spunmelt, SMS (spunbonded/meltblow/spunbonded) type, or a combination thereof.

Preferably, the film, or fabric, or nonwoven fabric, comprises one or more of the following: polypropylene, polyethylene, polypropylene/polypropylene bicomponent elements, polyamide.

According to preferred embodiments, the support layer has a weight comprised between 5 and 25 g/m ² .

According to preferred embodiments, the male part comprises a base layer, from which the plurality of appendices with attaching heads extends; each appendix comprising a shank extending from the base layer having a first maximum width, and a head having a second maximum width that is greater than the first maximum width.

The head is preferably of the mushroom-type, preferably projecting from opposite sides of the respective shank. The maximum width of the heads is preferably comprised between 0.1 mm and 0.80 mm, and more preferably between 0.20 mm and 0.60 mm. According to a further aspect, the invention relates to a female part of a reversible tear-off closing/opening device according to one or more of the previous embodiments, or combinations thereof.

According to a further aspect, the invention also relates to a material for female part of reversible tear-off closing/opening devices suitable to couple to a respective male part comprising a plurality of appendices with attaching heads of given dimensions, the material comprising a support layer and a fibrous structure provided on the support layer for receiving the attaching heads, characterized in that the fibrous structure comprises

- a first fibrous layer provided above the support layer, provided with first fibers, the first layer being provided with a first value of average titre of the fibers, the interstices between the first fibers defining spaces - of dimensions equal to or greater than the given dimensions - for receiving the attaching heads of the male part of the device, to which the female part formed by the material shall couple,

- a second fibrous layer provided above the first fibrous layer, provided with second fibers, having a second value of average titre of fibers that is lower than the first value of average titre, so that the interspaces between the second fibers have dimensions smaller than the given dimensions and are therefore not dimensionally suitable to receive the attaching heads of the male part, to which it shall couple.

In this way, when coupling the male part to the female part, the attaching heads are forced to cross the second fibrous layer that is thus reversibly deformed, allowing the attaching heads to enter the first fibrous layer and to be received in the receiving spaces; when the attaching heads are housed in the first layer, the second fibrous layer has returned into a substantially not- deformed status and prevents the attaching heads from exiting from the housing seats.

Preferably, the ratio between the value of average titre of the first fibers and the value of average titre of the second fibers is greater than or equal to 2, preferably comprised between 2 and 5. Preferably, the second value of average titre of the second fibers is comprised between 1 .1 dtex and 4.4 dtex and the first value of average titre of the first fibers is comprised between 4.4 dtex and 13.0 dtex.

According to preferred embodiments, the fibrous structure comprises a multi-layer nonwoven fabric.

The layers of the multi-layer nonwoven fabric are preferably formed by cut crimped fibers.

Preferably, the layers of the nonwoven fabric are joined together, preferably by means of through-air bonding or thermal bonding.

According to preferred embodiments, the fibers of these layers comprise thermoplastic fibers.

According to preferred embodiments, the fibrous structure is formed by a nonwoven fabric with a weight comprised between 20 and 50 g/m ² . According to preferred embodiments, the first fibrous layer is comprised between 60% and 80% of the overall thickness of the fibrous structure.

According to preferred embodiments, the second fibrous layer is comprised between 20% and 40% of the overall thickness of the fibrous structure.

According to preferred embodiments, the weight of the first fibrous layer is comprised between 50% and 75% of the overall weight of the fibrous structure.

According to preferred embodiments, the weight of the second fibrous layer is comprised between 25% and 50% of the overall weight of the fibrous structure.

According to preferred embodiments, the fibrous structure is joined to the support layer in bonding areas, where the thickness of the fibrous structure is lower.

Preferably, in the bonding areas the fibrous structure is joined to the support layer by means of at least partial fusion of its fibers on the support layer.

Preferably, at least part of the bonding areas are strips extending continuously between two opposite ends of the border of the female part. According to preferred embodiments, the fibers of the fibrous structure are of the thermoplastic type.

According to preferred embodiments, the fibers of the fibrous structure comprise one or more of the following: polyesters, polyolefins, polyamides and combinations or bicomponent structures thereof. Preferably the polyesters comprise PET, PBT, polyester copolymers, mixtures thereof; polyolefins comprise polyethylene (PE), polypropylene (PP), polybutene (PB), copolymers and mixtures thereof; bicomponent fibers comprise both concentric core/sheath structures and eccentric structures or side-by-side structures.

According to preferred embodiments, the support layer is realized by at least one film, at least one fabric, at least one nonwoven fabric, or a combination thereof. Preferably, at least one nonwoven fabric is of the spunbonded, spunmelt, SMS (spunbonded/meltblow/spunbonded) type, or a combination thereof.

Preferably the film, or fabric, or nonwoven fabric, comprises one or more of the following: polypropylene, polyethylene, polypropylene/polypropylene bicomponent elements, polyamide.

According to preferred embodiments, the support layer has a weight comprised between 5 and 25 g/m ² .

According to a further aspect, the invention relates to a method to produce a female part for reversible tear-off closing/opening devices, suitable to be coupled to a respective male part comprising a plurality of appendices with attaching heads, the method comprising the steps of

- providing a fibrous structure comprising

^■ a first fibrous layer provided above the support layer, provided with first fibers, the first layer being provided with a first value of average titre of the fibers, the interstices between the first fibers defining spaces for receiving the attaching heads of the male part of the device, to which the female part shall couple,

^■ a second fibrous layer provided above the first fibrous layer, provided with second fibers, having a second value of average titre of fibers that is lower than the first value of average titre, so that the interspaces between the second fibers are not dimensionally suitable to receive the attaching heads of the male part, to which it shall couple

- joining the fibrous structure to a support layer.

Preferably, the joining is of the thermal type, wherein part of the fibers of the fibrous structure are melt on the support layer in bonding areas; the joining being preferably performed by means of thermal calender or ultrasounds.

The fibrous structure is preferably produced by joining a layer of the first carded fibers with the second layer of the second carded fibers; the joining step being preferably performed by means of thermal bonding or through-air bonding or by using adhesive resin.

Preferably, according to the inventive method, the ratio between the value of average titre of the first fibers and the value of average titre of the second fibers is greater than or equal to 2, more preferably comprised between 2 and 5.

Preferably, according to the inventive method, the second value of average titre of the second fibers is comprised between 1 .1 dtex and 4.4 dtex and the first value of average titre of the first fibers is comprised between 4.4 dtex and 13.0 dtex.

Preferably, according to the inventive method, the fibrous structure comprises a multi-layer nonwoven fabric.

Preferably, according to the inventive method, the layers of the multi-layer nonwoven fabric are formed by cut crimped fibers.

Preferably, according to the inventive method the layers of the nonwoven fabric are joined together, preferably by means of thermal bonding or through- air bonding or by using adhesive resin.

Preferably, according to the inventive method, the fibers of these layers comprise thermoplastic fibers.

Preferably, according to the inventive method, the fibrous structure is formed by a nonwoven fabric with a weight comprised between 20 and 50 g/m ² .

Preferably, according to the inventive method, the first fibrous layer is comprised between 60% and 80% of the overall thickness of the fibrous structure. Preferably, according to the inventive method, the second fibrous layer is comprised between 20% and 40% of the overall thickness of the fibrous structure.

Preferably, according to the inventive method, the weight of the first fibrous layer is comprised between 50% and 75% of the overall weight of the fibrous structure.

Preferably, according to the inventive method, the weight of the second fibrous layer is comprised between 25% and 50% of the overall weight of the fibrous structure.

Preferably, according to the inventive method, the fibrous structure is joined to the support layer in bonding areas, where the thickness of the fibrous structure is lower.

Preferably, according to the inventive method, the fibrous structure is joined to the support layer by means of at least partial fusion of its fibers on the support layer.

Preferably, according to the inventive method, at least part of the bonding areas are strips extending continuously between two opposite ends of the border of the female part.

Preferably, according to the inventive method, the fibers of the fibrous structure are of the thermoplastic type.

Preferably, according to the inventive method, the fibers of the fibrous structure comprise one or more of the following: polyesters, polyolefins, polyamides and combinations or bicomponent structures thereof. Preferably the polyesters comprise PET, PBT, polyester copolymers, mixtures thereof; polyolefins comprise polyethylene (PE), polypropylene (PP), polybutene (PB), copolymers and mixtures thereof; bicomponent fibers comprise both concentric core/sheath structures and eccentric structures or side-by-side structures.

Preferably, according to the inventive method, the support layer is realized by at least one film, at least one fabric, at least one nonwoven fabric, or a combination thereof. Preferably, at least one nonwoven fabric is of the spunbonded, spunmelt, SMS (spunbonded/meltblow/spunbonded) type, or a combination thereof. Preferably, according to the inventive method, the film, or fabric, or nonwoven fabric, comprises one or more of the following: polypropylene, polyethylene, polypropylene/polypropylene bicomponent elements, polyamide.

Preferably, according to the inventive method, the support layer has a weight comprised between 5 and 25 g/m ² .

Brief description of the drawings

Further characteristics and advantages of the present invention will be more apparent from the description of a preferred, although not exclusive, embodiment, illustrated by way of non-limiting example in the attached tables of drawings, wherein:

figure 1 is a schematic view of a closing/opening device of the reversible tear-off type according to the prior art, with a male part comprising appendices with mushroom-shaped head;

figure 2 is a schematic cross section of a closing/opening device of the reversible tear-off type according to the invention;

figures 3a, 3b, 3c are pictures, taken from the top and approximately 200x enlarged, of, respectively (from the left to the right), a NWF related to the secondo fibrous layer of the fibrous layer according to the invention, with average titre of fibers (staple fibers) equal to 2.2 dtex, to a film with mushroom- type appendices manufactured by Gottlieb Binder and related to the model Microplast® 85455-00, and to a first fibrous layer of the fibrous structure according to the invention, with average titre of fibers (staple fibers) equal to 5.0 dtex;

figure 4 is a table with pictures a, b, c, and d of four films of known type (respectively manufactured by Gottlieb Binder, 3M, and VELCRO), in cross- sectional view, for reversible tear-off closing/opening devices usable in the device according to the invention, with the indication of the dimensions of the mushroom-type appendices and of the thickness of the film from which the appendices extend;

figure 5 is a picture of an example of a portion of female part of a reversible tear-off closing/opening device according to the invention.

Detailed description of an embodiment of the invention With reference to the above cited figures, a reversible tear-off closing/opening device according to the invention is indicated as a whole with number 10. The device is designed for sanitary products or disposable or single-use garments. These products comprise, for instance, absorbent hygienic products (like baby or adult diapers) or sanitary garments, such as surgical scrubs.

The device 10 comprises a male part 1 1 , suitable to couple mechanically to a respective female part 12 (it is a hook-and-loop closing system).

The male part 1 1 comprises a film formed by a base layer 13, from which appendices 14 extend. Each appendix 14 has a shank 14A extending from the base layer 13, and an attaching head 14B for coupling to the female part 12. The appendices are also called hooks. The male part is also called hook material.

The attaching head 14B is a mushroom-shaped head (mushroom-type appendices), i.e. it projects from opposite sides of the respective shank 14A.

Practically, the shank has a maximum width "d" (or "first width", that is a shank dimension transverse to the extension axis of the shank), smaller than the maximum width "D" (or "second width") of the attaching head 14B.

Preferably, the second maximum width D of the attaching heads 14B is comprised between 0.1 mm and 0.80 mm, and more preferably between 0.20 mm and 0.60 mm. Figures 2 and 4 show some examples of appendices with so defined attaching heads, relating to male parts of the known type and usable in a device according to the invention.

The female part 12 is formed by a material (also called loop material) comprising a support layer 15, also called backing layer, onto which a fibrous structure 16 is arranged, joined thereto. The joining is preferably performed in bonding areas 17, for instance through thermal melting of the fibers of the structure 16 onto the support layer 15. In the bonding areas 17, the thickness of the fibrous structure 16 is lower with respect to the rest of the structure, thus practically forming a footprint. Otherwise, adhesives may be used, for example of the Holt Melt type, between the support layer 15 and the structure 16.

The fibrous structure 16 comprises a first fibrous layer 18 above the backing layer 15 provided with first fibers.

The first layer 18 is provided with a first value of average titre of the fibers, and the interstices between the first fibers define spaces for receiving the attaching heads 14B of the male part 1 1 of the device. Figure 3c shows a picture of the first layer.

The fibrous structure 16 also comprises a second fibrous layer 19 above the first fibrous layer 18 provided with second fibers, having a second value of average titre of fibers that is lower than the first value of average titre of the first layer 18, so that the interspaces between the second fibers, when they are in a rest status, i.e. in a not-deformed status, are not dimensionally suitable to receive the attaching heads 14B. Figure 3a shows a picture of the second layer 19. For example, it is possible to say that, generally speaking, the interspaces between the second fibers have, in the rest status, smaller dimensions than the attaching heads 14B.

From the viewpoint of operation of the device, when coupling the male part 1 1 to the female part 12, the attaching heads 14B are forced to cross the second fibrous layer 19 that is thus reversibly deformed, i.e. in this step the second layer takes a reversibly deformed status, thus allowing the attaching heads to pass. It is possible to state that, in the reversibly deformed status, the interspaces between the second fibers have dimensions equal to or greater than those of the attaching heads; clearly, the interspaces, being formed by a fiber distribution having a random component, even if regularity characteristics, are not all identical and have variable dimensions; therefore, the term "dimensions" of the interspaces means, in this context, average dimensions. The attaching heads, after having crossed the second layer, enter the first fibrous layer 18. Here, they are received in the receiving spaces defined by the interstices spaces, thanks to the wide dimension of these interstices, a function of the titre of the first fibrous layer.

When the attaching heads 14B are housed in the first fibrous layer 18, the second fibrous layer 19 has returned into a substantially not-deformed status and prevents the attaching heads from exiting from the housing interstices, obviously if not stressed by a user's action suitable to force the female part 12 to detach from the male part 1 1 , i.e. an action suitable to force the attaching heads 14B to pass through the second fibrous layer 19, that is "narrower" than the width of the attaching heads 14B.

Practically, the fibrous structure 16 is "asymmetrical" with respect to the two layers 18 and 19, and in particular it has an "asymmetry" with respect to the titre of fibers of the two layers forming it.

Preferably, the material (loop material) forming the female part 12 comprises carded nonwoven fabric (NWF) (in particular, the NWF constitutes the fibrous structure 16 and is therefore formed by the two layers 18 and 19 of different fibers denier and, consequently, different opening), the backing layer 15 and a plurality of bonding areas 17.

Adequately, the ratio between the value of average titre of the first fibers and the value of average titre of the second fibers is greater than or equal to 2, preferably comprised between 2 and 5.

For example, the second value of average titre of the second fibers is comprised between 1 .1 dtex and 4.4 dtex and the first value of average titre of the first fibers is comprised between 4.0 dtex and 13.0 dtex.

In the material of the female part 12, the bonding areas 17 between the backing layer 15 and the asymmetrical NWF 16 are realized by arranging the side of the fibrous structure 16 corresponding to the first layer 18 so that it faces towards the backing layer 15.

The bonding areas 17 follow geometrical or repetitive profiles and are practically footprints generated, for example, by means of thermal lamination techniques or ultrasound techniques.

It has been proven that, in case the bonding areas 17 are strips extending continuously between two opposite ends A and B of the border of the female part, as shown for instance in figure 5, the tear strength of the device 10 is greater.

The fibrous structure 16 is realized before the joining to the support layer 15. The joining of the first and the second layers 18 and 19 of the structure 16 forming the asymmetrical carded nonwoven fabric is directly performed in the cohesion process following the fiber carding in the production of the nonwoven fabric, and it has therefore no interruption.

The first and second fibers forming the first and second layers 18 and 19 are preferably thermoplastic crimped staple fibers. Preferably, these two layers are joined in order to produce the carded NWF by means of through-air bonding or thermal bonding processes.

The areas 20 of the part of fibrous structure 16 comprised between the lower bonding areas 17 are suitable to the interaction of the material with the attaching heads (hooks) 14B of the male part 1 1 of the closing/opening device.

In these areas, the asymmetry of the first and of the second layers 18 and 19 of the NWF constitutes a main feature. Asymmetry does not means a geometrical asymmetry; it mainly means the different linear density in dtex or dernier of the fibers (for example, cut or staple fibers) constituting the fibrous structure 16 of the NWF and, consequently, the "opening" (dimensions of the hollow areas) thereof. It is therefore possible to state that asymmetry means a functional asymmetry of the two layers composing the NWF 16.

The layers 18 and 19 may be constituted by fibers of a single type or by mix of fibers in a composition suitable to obtain a given average dernier of the layer.

In an embodiment, the asymmetrical nonwoven fabric is formed by a carded multilayer NWF using thermoplastic crimped staple fibers. In an embodiment, the overall weight of the fibrous structure constituted by the asymmetrical NWF 16 is comprised between 25 and 50 g/m ² (gram per square meter).

Preferably, the first fibrous layer 18 is comprised between 60% and 80% of the overall thickness of the fibrous structure and the second fibrous layer 19 is comprised between 20% and 40% of the overall thickness of the fibrous structure.

Analogously, the weight of the first fibrous layer is comprised between 50% and 75% of the overall weight of the fibrous structure and the weight of the second fibrous layer is comprised between 25% and 50% of the overall weight of the fibrous structure.

In this example, the closer second layer 19 of NWF, exposed towards the use side, is constituted by fibers (identical or in mix) with average linear density comprised between 1 .5 and 3.3 dtex, i.e. fibers of low denier giving softness and pleasure to touch. The more open first layer 18 of NWF, exposed towards the side of the backing layer 15, is constituted by fibers (identical or in mix) with average linear density comprised between 4.0 and 10.0 dtex, i.e. fibers with significantly higher dernier, generating a structure with more hollow spaces between the fibers.

The ratio between the average dtex of the layer 18 and of the layer 19 is preferably greater than or equal to 2.

The nature of the thermoplastic fibers constituting the NWF 16 comprises, although without limiting the scope of the invention, polyesters, polyolefins, polyamides and combinations or bicomponent structures thereof. Polyesters comprise PET, PBT, polyester copolymers (for example iso-phtalic-acid-based melting fibers) and mixtures thereof. Polyolefins comprise polyethylene (PE), polypropylene (PP), polybutene (PB), copolymers and mixtures thereof. Bicomponent fibers comprise both concentric core/sheath structures and eccentric (not axial) structures or side-by-side structures. The techniques for joining the crimped thermoplastic fibers comprise through-air bonding, thermal bonding, resin bonding and point bonding by means of heat, ultrasounds or microwaves.

The backing layer 15 is formed by a dimensionally stable material with low grammage, preferably comprised between 5 and 20 g/m ² . Non-limiting examples are films, spunbonded nonwoven, spunmelt nonwoven or combinations thereof (for example SMS). The constituents may be polypropylene, polyethylene, PP/PE bicomponents, polyamide.

Figure 3, thorough 200x enlarged views, highlights the different openings features, i.e. the features of dimension of the hollow spaces between the fibers constituting the layers 18 and 19 of an exemplary asymmetrical NWF constituting the fibrous structure 16 according to the invention, and compares them to the dimensions of some hook materials (models 85455-00 and 85641 - 00 produced and marketed by Gottlieb Binder) with mushroom-type appendices. The second layer 19 of NWF has fibers with average titre equal to 2.2 dtex and is characterized by dimensions of the openings of the NWF that do not allow to receive the attaching heads of the appendices taken as a reference; they can only receive the shanks of the hooks. Vice versa, the openings of the NWF of the first open layer 18, characterized by fibers with average titre equal to 5.0 dtex, allow to receive also the attaching heads of the hooks.

As mentioned, based on the dimensional features of the two layers 18 and 19 of the NWF forming the fibrous structure 16 of the female material 12, the mechanism of operation is realized, on micrometric scale, of buttons and buttonholes: the mushroom-type hooks, analogously to buttons of micrometric dimensions (for instance with the diameter of the head approximately equal to 400-600 μ), find suitable buttonholes in the first fibrous layer 18, characterized by inter-fibers openings of smaller dimensions than the dimensions of the attaching heads 14B but sufficient for allowing the passage of the shank of the appendix from which the head 14B extends (the shank usually having dimensions comprised between 150 e 250μ). Once having crossed the second fibrous layer 19, the heads of the hooks enter into the first fibrous layer 18 of the NWF 16, with inter-fibers openings suitable to receive the heads 14B of the hooks (between 300 and 600 μ when the structure is relaxed).

The innovation of the "asymmetrical" loop material is evident when it is compared with the closing systems with "symmetrical" loop materials, especially if used together with mushroom-type hooks. In fact, when coupling the traditional closing/opening systems, due to the homogeneous nature of the structures of the loop material, the hooks cannot significantly penetrate into the NWF (see figure 1 ) and the bond strength of the closing system is due to loops or small portions of fiber forming a loop for the hooks. Vice versa, an "asymmetrical" material having on the surface a second fibrous layer with dimensions of the openings allowing to receive the shanks of the hooks, but engaging the heads thereof, and an innermost first fibrous layer suitable to receive the hooks heads, allows to achieve a significantly more effective penetration of the hooks (figure 2).

Figure 1 shows a traditional reversible tear-off closing/opening device 10ST, with a female part 12ST of the traditional type, i.e. having a non- multilayer fibrous structure 16ST, i.e. there is not "asymmetry" in the fibers titre along the depth of the fibrous structure suitable to receive the mushroom-type heads 14BST of the appendices of the male part 1 1 ST. When the closing device 10ST is mechanically coupled, the hooks 14ST exert a compression onto the female layer 16ST, but, due to the reduced dimension of the openings (i.e. the spaces between the fibers) of the fibrous structure, they are not able to cross a significant portion of the material. The closure operation is based on the fact that small portions of fiber capture (through looping) the hooks.

Figure 2 shows a device 10 according to the invention. When the male part 1 1 and the female part are mechanically coupled, the compression exerted allows the heads 14B of the hooks 14 to cross the second closed (low denier) layer 19 of the female material 12, achieving the first layer 18, more open (high denier) where the head 14B can relax, remaining trapped therein (like buttons in the buttonholes).

Figure 4 shows cross-sections of hook materials of the known type usable with the present invention.

Below a comparison is made of the bond strength in a closing/opening device of the known type and in a closing/opening device according to the invention.

Test of the bond strength between the male part and the female part

ASTM test for 90 Degree Peel Resistance

The 90 degree peel resistance test has been performed according to the standards ASTM, using a dynamometer model Instron 4464 H1997 (Cressex Business Park, 9 Coronation Road, High Wycombe HP12 3SY, United Kingdom). According to the test, a 13 x 25 mm hook tape (if not differently indicated, a hook tape Gottlieb Binder model Microplast® 85455-00 is used) has been made adhere to the loop material, and then uncoupled by peeling it at a 90° angle. The maximum resistance-to-peel load required to uncouple the two components has been recorded in Newton (N). EDANA test for thickness (EDANA Test Method 30.5-99)

The thickness has been measured according to the harmonized test method EDANA 30.5-99, using a thickness gauge KARL SCHRODER KG equipped with a dial gage Sylvac model S229. The values are in millimeters (mm).

EDANA test for arammaae or basis weight (EDANA Test Method 40.3-90)

The grammage has been measured according to the harmonized test method EDANA 40.30-90 using a balance Mettler Toledo model ML303/01 . The values are in grams per square meter (gsm or g/m ² )

EDANA test for air permeability (EDANA Test Method 140.2-99)

The air permeability test measures the rate of air flow passing perpendicularly through the specimen of nonwoven under specific conditions. The parameter has been measured according to the harmonized test method EDANA 140.2-99 using an air permeability tester manufactured by Testex AG Toledo, model ML303/01 . The values are in meters per second (m/s).

Example

Reels of the two composite loop materials (female parts) have been produced by using the same pattern illustrated in figure 5, and then cut into reels and wound under analogous stretching conditions. Specimens of the two materials have been taken in similar positions of the reels, and have been tested for 90° peel resistance.

According to the 90° peel resistance test, a hook tape (male part) Gottlieb

Binder model Microplast® 85455-00, dimensions 13 x 25 mm, has been coupled to the specimens. The maximum resistance-to-peel load required to uncouple the two components by peeling at a 90° angle has been recorded in Newton (N).

Specimen 1 (loop material - female part - of the known type)

Structure: Component Description Grammage

backing layer (support spunbonded bicomponent 14 g/m ²

layer): PP/PE

carded NWF (single-layer through-air bonded prepared 35 g/m

fibrous structure): with 2.2 dtex fibers in PET/PE

- specimen grammage: 48.8 g/m ²

- thickness: 0.70 mm (backing layer thickness 0.15 mm; carded NWF thickness 0.55 mm)

air permeability: 1 .54 m/s

bonding area: 14,8 %

engraving pattern: waves, see figure 5.

Specimen 2 (asymmetrical loop material - "asymmetrical" female according to the present invention)

Structure:

- specimen grammage: 48.3 g/m ²

- thickness: 0.74 mm (backing layer thickness 0.15 mm; thickness carded nonwoven 0.59 mm, 31 % of which layer x and 69% layer y)

- air permeability: 1 .51 m/s

- bonding area: 14,8 %

- engraving pattern: waves, see figure 5.

The bond test result is shown in the following table. Specimen 1 Specimen 2

90 degree Peel ASTM 7,6 ± 0,8 (N/25 mm) 12,7± 1 ,6 (N/25 mm)

5

Average values of 5 data

It is clearly evident that the specimen 2, representing a closing/opening device according to the invention, wherein an innovative characteristic element is particularly represented by the second female part (i.e. a new loop material), ensures a significantly higher bond strength with respect to devices using a traditional structure of female part.

It is understood that what illustrated above purely represents possible non-limiting embodiments of the invention, which may vary in forms and arrangements without departing from the scope of the concept on which the invention is based. Any reference numbers in the appended claims are provided for the sole purpose of facilitating the reading thereof in the light of the description before and the accompanying drawings and do not in any way limit the scope of protection of the present invention.