Patent Application
20240366436
The present invention relates to an elastic laminate which is intended to be used in the field of hygiene, and in particular for nappies or adult incontinence pants, the laminate extending in accordance with a given width corresponding to the direction CD (Cross Direction or Transverse Direction) and a large length corresponding to the unwinding direction during the manufacture of the laminate, referred to as the direction MD (Machine Direction), and comprising one stack of a nonwoven layer and at least one elastic film extending over a width that is less than or equal to said given width, in particular two lower and upper layers of nonwoven sandwiching the at least one elastic film. These laminates are particularly intended for use in the manufacture of elastic lugs intended to carry hooks and to be fixed to the edges of the rear central part of the waist of a nappy to engage with the loop elements originating from the front part of the waist to create a movable and elastically adjustable closure for the nappy.
A laminate of this type is known for example from document EP-A-1783257, in the name of the applicant.
Although this elastic laminate from the prior art has considerable advantages with respect to that which existed previously, it is desirable to improve it further, and in particular to increase its user comfort, in particular its apparent capacity, when it is in the form of an elastic lug of a waist of the nappy, for being stretched without the user having the impression that the laminate will break due to the stretching. It would also be desirable to improve its softness to the touch in the stretched state.
The present invention thus relates, according to a first aspect, to an elastic laminate, extending widthwise in a first direction, specifically CD, and lengthwise in a second direction, specifically MD, comprising:
The present invention also relates, according to the first aspect, to an elastic laminate, extending widthwise in a first direction, specifically CD, and lengthwise in a second direction, specifically MD, comprising:
Preferably, the undulations extend, in the second direction, specifically MD, over the entire length of the at least one nonwoven layer, in particular over the entire length of the laminate, the length of the laminate being in particular greater than 20 mm, in particular greater than 30 mm, more particularly greater than 40 mm, even more particularly greater than 60 mm.
Preferably, the nonwoven layer or layers forming the at least one nonwoven layer extend(s) in the first direction over a total nonwoven width, in particular in the direction CD, and the elastic film or films forming the at least one elastic film extend(s) over a total elastic width, the ratio equal to the total elastic width to the total nonwoven width being between 0.3 and 0.9, preferably between 0.4 and 0.8.
Preferably, the curved sections extend in the first direction over a total curved section width, in particular in the direction CD, and the intermediate sections extend over a total intermediate section width, the ratio equal to the total curved section width to the total width of the nonwoven being between 0.25 and 0.85, preferably between 0.35 and 0.75.
Preferably, according to another aspect of the invention itself forming an invention, independently of the other aspects of the invention, and in particular independently of the first aspect, but which can also be implemented in a favourable manner in combination with each of these other aspects, and in particular with the first aspect,
According to the invention, for a given initial thickness, the laminate, in the stretched state, is thicker than the laminates of the prior art, giving the user an impression of greater sturdiness when they stretch the laminate, in particular when it forms an elastic lug for closing the waist of a nappy. The laminate is also easier to manufacture and is softer to the touch and/or has a more bulky or voluminous visual appearance.
Preferably, the curve giving the relative loss of thickness [(e0−e(t))/e0] as a function of the elongation (t) has a maximum value of greater than 10%, even more preferably greater than 20%.
Preferably, the so-called maximum elongation according to the first direction or according to the second direction is between 50% and 100%.
Preferably, the ratio of the initial thickness (e0) minus the thickness (emax) of the laminate at maximum elongation over the initial thickness (e0), i.e. the ratio [(e0−emax)/e0], is less than or equal to 55%, in particular less than 40%, in particular less than 35%, and/or is greater than 5%, in particular greater than 10%, in particular greater than 20%.
Preferably, the ratio of the initial thickness (e0) minus the thickness (e100) of the laminate at 100% elongation over the initial thickness (e0), i.e. the ratio [(e0−e100)/e0], is less than or equal to 55%, in particular less than 40%, in particular less than 35%, and/or is greater than 5%, in particular greater than 10%, in particular greater than 20%.
Preferably, the laminate, after stretching to an elongation of 100% proceeding from the initial state before its first stretching, and then relaxation to the non-stretched state (0% elongation), has a thickness (ev) greater than the initial thickness (e0), and the ratio [(ev−e0)/e0] is greater than 2%, in particular greater than 5%, more particularly greater than 10%, and is preferably less than 70%, in particular less than 50%, more particularly less than 35%.
Preferably, the laminate, after stretching to an elongation of 100% proceeding from the first non-stretched state and then relaxation to a second non-stretched state (0% elongation), has a thickness (ev), and the ratio of the thickness (ev) minus the thickness (e100) of the laminate at 100% elongation over the thickness, i.e. the ratio (ev) [(ev−e100)/ev], is less than or equal to 60%, in particular less than 50%, in particular less than 40%, in particular less than 35%.
According to a preferred embodiment, fixing of the at least one film to the at least one nonwoven layer is performed by interposition of an adhesive, for example glue, along a strip or a plurality of strips or lines of glue extending lengthwise in the second direction, in particular MD, and at a distance from one another in the first direction, in particular CD, with a constant or variable pitch and/or discontinuities in the direction MD.
According to another embodiment, fixing of the at least one film to the at least one nonwoven layer is performed by hot lamination of the elastic film on at least one of the two nonwovens, in some cases by hot lamination of the elastic film on two upper and lower nonwovens.
According to yet another embodiment, fixing of the at least one film to the at least one nonwoven layer is performed by hot calendering and/or by ultrasonic welding.
Preferably, the at least one nonwoven layer comprises continuous filaments.
Preferably, the at least one nonwoven layer comprises crimped filaments.
Preferably, the at least one nonwoven layer comprises a spunbond nonwoven.
Preferably, the at least one nonwoven layer comprises a nonwoven obtained by melting, in particular a layer of spunbond (S), in particular a spunbond based on crimped filaments, and a layer of meltblown (M), or a combination of a plurality of these layers (for example SM, SMS, SMMS, SSMMS, SSSMMS, SSSMMSS).
According to another aspect of the invention, itself forming an invention independent of the aspect(s) above but which can advantageously be implemented in combination therewith, the laminate, after stretching for the first time to an elongation of 100%, and then relaxation to a second non-stretched state (0% elongation), has a thickness (ev) greater than the initial thickness (e0) before it is stretched for the first time, and the ratio [(ev−e0)/e0], is greater than 2%, in particular greater than 5%, more particularly greater than 10%, in particular greater than 12.5%, even more preferably greater than 15%, and/or is preferably less than 70%, in particular less than 50%, more particularly less than 35%.
According to this aspect, it is thus possible to roll a greater length of a laminate that is not yet stretched (at the output of the production line) onto a reel of constant diameter, while having available a laminate of the same quality in use, or to roll a same length of laminate that is not yet stretched, onto a reel of constant diameter, while having available a laminate of better quality in use.
According to yet another aspect of the invention, itself forming an invention independent of the preceding aspects but which can advantageously be implemented in combination with each or a plurality thereof, an elastic laminate, extending widthwise in a direction CD and lengthwise in a direction MD, comprises:
the curve giving, during the first stretching, the force (N) applied to the laminate in the direction CD as a function of the stretching (elongation or extension as a %) having an inflection point that separates a first lower curve segment having its concavity turned downwards, and a second upper curve segment having its concavity turned upwards, the first lower segment having a lower apex point and the second upper segment having an upper apex point, the portion of the curve between the origin and the lower apex point being the initiation segment of the curve, the portion of the curve between the lower apex point and the inflection point being the usage segment of the curve, and the portion of the curve between the inflection point and the upper apex point being the stop segment of the curve, and the X-axis of the initiation segment extends between 0% and a value of between 5% and 20%, for example 10%, and the X-axis of the usage segment extends between a value of between 5% and 20%, for example 10%, and a value of between 60% and 80%, for example 70%, while the X-axis of the stop segment extends, following the usage segment, up to a value of between 80% and 120%, in particular, as mentioned in the paragraph above, 100%.
According to a favourable embodiment, the laminate is such that, in a non-stretched state of the laminate and/or of the elastic film, the nonwoven layer comprises, alternately, in the transverse cross-section CD, intermediate sections, in particular straight or substantially straight, in particular curved, in particular having their concavity turned upwards, extending in the direction CD while being fixed to the elastic film, and inverted U-shaped curved sections, in particular in the shape of a Ω, each consisting of two strand sections proceeding from two successive intermediate sections and meeting at an apex, which are not fixed to the elastic film and remain at a distance therefrom, so as to define empty spaces between them and the elastic film, the curvature of the curved sections being greater than that of the intermediate sections.
By thus providing that the nonwoven layer is fixed to the elastic film only intermittently, a type of limitation of the possible stretching of the laminate is obtained, in particular when the temperature at which the laminate is used, for example when it is used on a nappy, increases significantly, for example approaching 30° C., which has the effect of significantly increasing the stretching capacity of the elastic film. Thus, in particular at this temperature, when the user stretches the laminate in the direction CD, at the moment when the inverted U-shaped sections flatten out between the two feet, in parallel with the direction of stretching and with the fixing section, they feel a type of stop, prompting them not to stretch the laminate any further, even though, at these body temperatures, they could stretch the elastic much further, to the point that the long-term stability of the laminate deteriorates.
The laminate is thus prevented from deteriorating too rapidly, by combatting the phenomenon of “neckdown” or shrinkage of the elastic which appears, for example in the case of a nappy, gradually during use of the nappy, for example by being opened and then closed, repeatedly, in particular when it is stretched too much. Furthermore, a laminate is obtained that is easier to manufacture and is softer and/or has a more bulky or voluminous visual appearance.
Preferably, the intermediate sections, in particular straight or substantially straight intermediate sections, in particular when they are curved with their concavity turned upwards, each extend over a distance, measured in the direction CD, which is less than 10% of the distance, measured in the direction CD, between the two intermediate sections from which the two strand sections of an inverted U-shaped section, in particular in the shape of a Ω, originate, in particular is between 10% and 50% of this distance.
According to yet another aspect of the invention, itself constituting an invention independent of the aspects above, but which can advantageously be implemented in combination with each or a plurality of said aspects, the elastic film based on an elastomer composition does not have an outer skin, the elastic film preferably being sufficiently adhesive and/or tacky to hold the nonwoven on one or more intermediate sections without glue.
According to yet another aspect of the invention, the elastic film comprises a skin, preferably two skins, forming an outer surface of the elastic film.
Very preferably, at least one strip or line of adhesive, in particular glue, is located between the elastic film and a respective intermediate section.
Preferably, the height of the inverted U, in particular in the shape of a Ω, (height of the apex point) is greater than its width (distance between the two feet of the strands of the inverted U.
In particular, in a favourable manner, each inverted U is in the shape of a Ω, and is defined by two left-hand and right-hand strands originating from a respective straight section and meeting at the apex of the inverted U, and one of the two left-hand or right-hand strands of at least one of the inverted U-shaped sections, in particular the two left-hand and right-hand strands of at least one inverted U-shaped section has/have, in a starting zone proceeding from the straight section from which it/they originate, a respective curved shape, the concavity of which is turned towards the elastic film.
Preferably, an additional nonwoven layer is provided, on the other side of the elastic film, said additional layer being a nonwoven layer based on short fibres consolidated by water jets or thermally, in particular a hydrobonded carded nonwoven (spunlace) or a carded thermobonded nonwoven.
Preferably, the nonwoven layer has a first basis weight and the additional nonwoven layer has a second basis weight which is different from the first basis weight, in particular greater than the first basis weight, in some cases the first and second basis weights being equal to within 20%.
In particular, the nonwoven layer has a first apparent basis weight, and the additional nonwoven layer has a second apparent basis weight, in the elastic zone, the first apparent basis weight is greater than the second apparent basis weight, the apparent basis weight being determined by measuring, in a cross-sectional view according to an axis CD, the evolution of the product and, by multiplying the evolution by the basis weight of the nonwoven in the non-stretched and/or non-shaped state.
In particular, the nonwoven layer has a first rigidity and the additional nonwoven layer has a second rigidity which is less than the first rigidity, in particular the nonwoven layer has an elongation in CD at 5 N of less than 70%, and the additional nonwoven layer has an elongation in CD at 5 N of greater than 70%.
According to one example, the length of the elastic film in the first direction, in particular CD, of the laminate is less than the width of the lap or nonwoven layer in the first direction, in particular CD, of the laminate.
According to one example, which may be combined or not with the previous example, the width of the elastic film in the second direction, in particular MD, of the laminate is equal or substantially equal to the length of the lap or nonwoven layer in the second direction, in particular MD, of the laminate.
The present invention also relates to a method for producing a laminate, in particular a laminate according to the invention.
According to the invention, the method comprises the steps in which an elastic film is taken; a nonwoven layer, in particular having continuous filaments, in particular a spunbond, in particular a “crimped” spunbond, is taken; the nonwoven layer is shaped to obtain a nonwoven layer in the shape of waves having, in transverse cross-section, the shape of a succession of inverted U shapes which are separated by intermediate sections, in particular straight or substantially straight, or curved or substantially curved, having their concavity turned upwards, the curvature of the curved sections being greater than that of the intermediate sections, the curvature of the latter being in particular zero when they are straight and close to zero when they are substantially straight; and the wave-shaped nonwoven layer is fixed to the elastic film, preferably in a non-stretched state thereof, by the side of the layer of the nonwoven that is opposite the crests of the waves.
Preferably, the filaments are oriented in the direction MD.
Preferably, in order to form (shape) the nonwoven layer, said layer is passed between the toothed or serrated rollers.
Preferably, prior to fixing the wave-shaped nonwoven layer to the elastic film, a strip of adhesive, in particular of glue, is deposited over the entire width of the elastic film, and the wave-shaped nonwoven layer is then laminated onto the elastic film.
According to another embodiment, the elastic film is hot-extruded between a support roller and the waver into which the upper nonwoven passes.
The present invention also relates to a nappy for a baby or adult incontinence pants comprising at least one laminate according to the invention, in particular in order to form the hook tabs originating laterally from the rear waist of the nappy or incontinence pants, such that the hooks engage with loops originating from the front face of the waist of the nappy, in order to achieve closure of the nappy or incontinence pants.
The present invention also relates to an elastic laminate with hooks, comprising a laminate according to the invention and at least one lap with hooks fixed to the laminate, in particular on the upper nonwoven layer, preferably in a zone without a wave or inverted U.
The present invention also relates to a roller comprising a laminate according to the invention, said laminate having a length at least greater than 1 meter and being rolled according to an axis perpendicular to the axis MD, said laminate comprising two adjacent elastic films.
The present invention also relates to a use of a laminate according to the first aspect of the invention, for obtaining an elastic laminate having an apparent capacity, in particular when it is in the form of an elastic lug of a waist of a nappy, for being stretched without the user having the impression that the laminate will break due to the stretching, in particular a laminate having an initial thickness (e0) before its first stretching, and when the laminate is stretched according to the first or the second direction up to a so-called maximum elongation, at least equal to 50%, the curve giving the relative loss of thickness [(e0−e(t))/e0] as a function of the elongation (t) has a maximum value of between 5 and 50%, preferably less than or equal to 40%, even more preferably less than 35%, in particular less than 30%.
Preferably, the curve giving the relative loss of thickness [(e0−e(t))/e0] as a function of the elongation (t) has a maximum value of greater than 10%, even more preferably greater than 20%.
Preferably, the so-called maximum elongation according to the first direction or according to the second direction is between 50% and 100%.
Preferably, the ratio of the initial thickness (e0) minus the thickness (emax) of the laminate at maximum elongation over the initial thickness (e0), i.e. the ratio [(e0−emax)/e0], is less than or equal to 55%, in particular less than 40%, in particular less than 35%, and/or is greater than 5%, in particular greater than 10%, in particular greater than 20%.
Preferably, the ratio of the initial thickness (e0) minus the thickness (e100) of the laminate at 100% elongation over the initial thickness (e0), i.e. the ratio [(e0−e100)/e0], is less than or equal to 55%, in particular less than 40%, in particular less than 35%, and/or is greater than 5%, in particular greater than 10%, in particular greater than 20%.
Preferably, the laminate, after stretching to an elongation of 100% proceeding from the initial state before its first stretching, and then relaxation to the non-stretched state (0% elongation), has a thickness (ev) greater than the initial thickness (e0), and the ratio [(ev−e0)/e0] is greater than 2%, in particular greater than 5%, more particularly greater than 10%, and is preferably less than 70%, in particular less than 50%, more particularly less than 35%.
Preferably, the laminate, after stretching to an elongation of 100% proceeding from the first non-stretched state and then relaxation to a second non-stretched state (0% elongation), has a thickness (ev), and the ratio of the thickness (ev) minus the thickness (e100) of the laminate at 100% elongation over the thickness, i.e. the ratio (ev) [(ev−e100)/ev], is less than or equal to 60%, in particular less than 50%, in particular less than 40%, in particular less than 35%.
In particular, the laminate according to the invention has a greater length than width, in particular in a ratio greater than 1.1, in particular greater than 1.25, in particular greater than 2, in particular greater than 50, more particularly greater than 100, and preferably less than 10,000, 5,000, 2,000 or 1,000. In particular, the laminate is rolled and/or unrolled, in particular in its lengthwise direction.
By way of example, a plurality of embodiments of the invention will now be described, with reference to the drawings, in which:
In
The two elastic films 2d, 2g extend in the direction CD over a smaller distance than the distance over which the two nonwoven layers 1 and 3 extend, such that two edge regions and a central region without elastic film are formed on the left-hand and right-hand edges of the laminate and in the centre.
The upper nonwoven layer 1 and the elastic films 2d, 2g are fixed by interposition, therebetween, of a strip 4 of adhesive, in particular glue.
In the same way, the lower nonwoven layer 3 and the elastic films 2d, 2g are fixed by interposition, therebetween, of strips or lines 5d, 5g of adhesive, in particular glue, which extend lengthwise in the direction MD and are spaced apart from one another in the direction CD.
In the regions without elastics, the two nonwovens 1 and 3 are fixed directly to one another (i.e. without interposition of elastic film, only the adhesive being present therebetween) by fields 6d, 7d, 6c, 7c, 6g, 7g, respectively right, central and left, extending in the direction MD and having a width that is substantially equal to the respective width of the edge and central regions.
In cross-section CD, as in
Each inverted U-shaped section comprises two sections in the form of a strand, respectively 10g left-hand and 10d right-hand, each originating from a respective intermediate section 9, which meet at the apex of the inverted U-shaped section.
Each of the two left-hand or right-hand strands of the inverted U-shaped sections has, in a starting zone proceeding from the straight section from which it originates, a respective curved shape, the concavity of which is turned towards the elastic film.
The inverted U-shapes may have a width (distance in parallel with the direction CD between the two straight sections from which the inverted U originates) of between 0.5 mm and 2 mm, and a height of between 0.5 mm and 2 mm, in particular between 0.9 mm and 1.8 mm.
The intermediate sections may have a length, in the direction MD, that is greater than 3 mm, in particular greater than 5 mm, in particular greater than 10 mm, and/or over the entire length in MD of the laminate and/or the entire length in MD of the laminate in the form of an elastic lug, in particular less than 100 mm. The intermediate sections extend in a continuous or discontinuous manner in the direction MD.
The intermediate sections may have a width of between 0.4 mm and 2 mm, in particular between 0.4 mm and 1.9 mm, in particular between 0.5 mm and 1.5 mm. In particular, said width is less than 10% of the width of the inverted U shapes, in particular is between 10% and 50% of said width, even more preferably between 10% and 30% of said width of the inverted U shapes in the non-stretched state.
As can be seen from
The curved sections 10 of the upper nonwoven extend in the direction CD over a total curved section width, and the intermediate sections 9 extend over a total intermediate section width, the ratio equal to the total curved section width over the total width of the nonwoven being between 0.25 and 0.85, in particular between 0.35 and 0.75, and in particular being equal to approximately 0.45 in
The width of the lines or strips of adhesive, in particular glue, may be between 0.5 mm and 3 mm, or between 10 mm and 80 mm.
Furthermore, according to an advantageous embodiment, at least one of the lines or strips of glue is located between an elastic film 2d, 2g and one of the intermediate sections 9 of the upper nonwoven layer 1, and has a width in the direction CD that is strictly less than that of said one of the straight sections 9. In particular, some of the lines or strips of glue, in particular all the lines or strips of glue, are each located between an elastic film 2d, 2g and a respective one of the intermediate sections 9 of the upper nonwoven layer 1, and each have a width in the direction CD that is strictly less than that of said one respective one of the intermediate sections 9.
According to another different embodiment, all the lines or strips of glue are each located between an elastic film 2d, 2g and a respective one of the sections 9 of the upper nonwoven layer 1, and each have a width in the direction CD that is equal to that of said one respective one of the sections 9.
The upper nonwoven layer 1 is formed from a nonwoven based on continuous filaments, i.e. filaments with a long length, in particular 120 mm or more. In particular, the nonwoven of the nonwoven layer 1 may be a spunbond or comprise a spunbond associated with other nonwovens, for example an SM, an SMS, or the like.
The upper nonwoven layer 1 may have a basis weight of between 10 and 30 g/m2, in particular between 10 and 22 g/m2.
The lower nonwoven layer 3 may also be formed from continuous filaments, but, and preferably, also from any other nonwoven, in particular based on short fibres, in particular a carded material, such as a spunlace.
The lower nonwoven layer 3 may have a basis weight of between 10 and 30 g/m2, in particular between 18 and 25 g/m2.
The thickness of the upper nonwoven layer (measured perpendicularly to the straight sections, in the resting state and in fresh air without application of pressure on the nonwoven) may be between 0.5 mm and 2 mm.
The thickness of the lower nonwoven layer (measured perpendicularly to the straight sections, in the resting state and in fresh air without application of pressure on the nonwoven) may be between 0.1 mm and 0.5 mm.
The strips of glue 5d, 5g, as well as the fields of glue 7d, 7c and 7g, have been deposited on a nonwoven layer, for example spunlace, 25 g/m2, intended for forming the lower nonwoven layer 3, and the two elastic films 2g, 2d have been deposited on top, in order to obtain the intermediate laminate in
Alternatively, a precursor nonwoven layer intended to form the upper nonwoven layer has been shaped by passing it into the installation shown in
Subsequently, the strip 4 of glue as well as the fields of glue 6d, 6c and 6g are deposited on the intermediate laminate in
Subsequently, the nonwoven layer in
It is then possible to perform activation of the laminate in
According to a variant, it is also possible to perform activation of the lower nonwoven layer after formation of the laminate in
According to the invention, it is possible to use a glue such as glues of the non-reactive PSA (pressure-sensitive adhesive) type, for example H2465 by Bostick, or a reactive PU glue, in particular XPU18314 by Bostik. Preferably, these glues will have a chemical nature similar to the elastomer film. For example, if one of these glues is analysed using an infrared spectrometer, in order to identify the chemical functions, or using liquid chromatography to separate and quantify the substances, preferably traces of one or more components or their derivatives, of the material or materials of the elastomer film, will be identified.
Preferably, these glues are based on SIS, SBS, SEBS and SEPS, allowing for good affinity with the film due to the similar chemical materials.
Preferably, the glue layer has a basis weight of less than 15 g/m2, in particular less than 12 g/m2, more preferably less than 8 g/m2.
In the present invention, a nonwoven is intended to mean a product obtained following formation of a lap of fibres and/or filaments which has been consolidated. The consolidation may be mechanical, chemical or thermal, and results in the presence of bonds between the fibres and/or the filaments. This consolidation may be direct, i.e. performed directly between the fibres and/or the filaments by means of welding, or it may be indirect, i.e. by means of an intermediate layer between the fibres and/or the filaments, for example a layer of glue or a layer of binder. The term “nonwoven” relates to a structure in the form of a tape or lap of fibres and/or filaments which are interlaced in a non-uniform or irregular manner, or at random. A nonwoven may have a single-layer structure or a structure comprising a plurality of layers. A nonwoven may be made from different synthetic and/or natural materials. The natural materials, by way of example, are cellulose fibres such as cotton, jute, paper pulp, linen or the like, and may also include recycled cellulose fibres, such as rayon or viscose (cellulose acetate). The natural fibres for a nonwoven material may be prepared by using various processes, such as carding. Synthetic materials, by way of example but without restriction thereto, include synthetic thermoplastic polymers, which are known to form fibres and/or filaments which include, without restriction thereto, polyolefins, for example polyethylene, polypropylene, polybutylene, and the like; polyamide, for example polyamide 6, polyamide 6.6, polyamide 10, polyamide 11, polyamide 12, and the like; polyesters, for example polyethylene terephthalates, polybutylene terephthalates, polylactic acids (PLA), and the like, polycarbonates, polystyrenes, thermoplastic elastomers, vinyl polymers, polyurethanes, and mixtures and co-polymers thereof. Some of these materials may be bioplastic, for example bio-sourced (for example bio-PE, PLA or PHA (polyhydroxyalkanoates), polyamide 11, viscose (cellulose acetate), and the like) and/or biodegradable (PLA and the like). In a general manner, fibres and filaments differ mainly in their length and their manufacturing method.
“Continuous filaments” means the individual elements, which are very long compared to the diameter of their cross-section, extruded in a continuous manner in order to directly form a nonwoven lap, which can then be consolidated by thermobonding or any other means making it possible to achieve the desired performance, and/or transport thereof. Preferably, the continuous filaments have a length greater than 120 mm.
“Fibre” is understood as the generic term for denoting a textile material or a textile material element of reduced length, less than the length of the continuous filaments, and able to be spun and/or used in the formation of nonwovens. Two types of fibres are distinguished, short fibres formed of discontinuous material of a short length less than 50 mm (preferably from 25 mm to 50 mm), and long fibres formed in a discontinuous manner and of a long length greater than 50 mm (preferably from 60 mm to 120 mm).
Unlike continuous filaments which are consolidated directly after extrusion, the fibres are usually oriented and organised in a lap during a carding step that is well known to a person skilled in the art. This lap can then be consolidated by thermobonding or any other means making it possible to achieve the desired performance, and/or transport thereof.
According to the present invention, “film” means a material of a sheet or wrap type, the length and the width of which are each much greater than the thickness (for example in a ratio of 10×, 50×, or even 1000× or more). Typically, a film has a thickness of less than 0.7 mm, in particular less than 0.5 mm or even thinner. In particular, a string or a thread or a set of strings and/or threads are not films.
By way of non-limiting examples of an elastomer material, the following can be cited: styrene/isoprene (SI), styrene/isoprene/styrene (SIS), styrene/butadiene/styrene (SBS), styrene-ethylene/butylene-styrene (SEBS), styrene-ethylene/propylene-styrene (SEPS) copolymers, or SIBS. Mixtures of these elastomers with one another or with non-elastomers which modify some characteristics other than elasticity may also be considered. For example up to 50% by mass, but preferably less than 30% by mass, of polymer may be added in order to modify some characteristics of the base materials (elasticity, heat resistance, processability, UV resistance, colouring, etc.), such as polystyrenes or poly a-methyl-styrene, epoxy polyesters, polyolefins, for example polyethylenes or some ethylene/vinyl acetates, preferably those having higher molar masses.
The elastomer material may in particular be a styrene-isoprene-styrene, available for example from the Kraton Polymers company, under the name KRATON D (registered trademark), or from the DEXCO POLYMERS LP company (United States) or TSRC (Europe) under the name VECTOR SBC 4211 (registered trademark), and/or under the name VECTOR SBC 4111 (registered trademark), and/or under the name VECTOR SBC 4411 (registered trademark), or a mixture of at least two of these materials. It is also possible to use TPE (thermoplastic elastomer) materials, in particular a thermoplastic elastomer of polyurethane, in particular ESTANE (registered trademark) 2102-75A-TPU from the LUBRIZOL company. It is also possible to use a styrene-butadiene-styrene, in particular VECTOR SBC 4461 (registered trademark) from the Dexco Polymers company a TSRC COMPANY LP. It is also possible to use a styrene-ethylene/butylene, or a styrene-ethylene-butylene-styrene (SEBS) copolymer sequence.
Without being exhaustive, the list can be supplemented by the use of all hydrogenated polyisoprene polymers such as styrene-ethylene-propylene-styrene (SEPS), styrene-ethylene-propylene-styrene-ethylene-ethylene-propylene (SEPSEP), hydrogenated polybutadiene polymers such as styrene-ethylene-butylene-styrene (SEBS), styrene-ethylene-butylene-styrene-ethylene-ethylene-butylene-ethylene-butylene-butylene (SEBSEB), styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-isoprene-butadiene-styrene (SIBS), hydrogenated polyisoprene/butadiene polymer such as styrene-ethylene-ethylene-ethylene-propylene-styrene (SEEPS), and hydrogenated vinyl-polyisoprene/hydrogenated polyisoprene/polyisoprene/polystyrene triblock polymers, such as HYBRAR 7311, which are commercially available (Kuraray America, Inc., Houston, Tex.), and combinations thereof.
Block polymer configurations such as diblock, triblock, multiblock, multiblock, star and radial are also envisaged in this disclosure. In some cases, sequenced copolymers of or higher molar masses may be desirable. Sequenced copolymers are available from Kraton Polymers U.S. LLC of Houston, Tex. under the names, for example, Kraton D1184, Kraton FG1901 and Kraton FG1924, and under the names Septon 8007 by the Kuraray company. Dynasol is another possible supplier of these polymers.
It is also possible to use an isooctyl acrylate and acrylic acid copolymer, according to monomer ratios of 90/10, which is a thermoplastic having physical cross-linking in the absence of a cross-linking agent.
Other possible materials are polyolefin polymers, mainly ethylene and/or propylene copolymers, having elastomer characteristics, in particular originating from metallocene catalysis, such as VISTAMAXX VM-1120 (registered trademark), available from the Exxon Mobil Chemical company, or indeed rubber-loaded polymers.
Examples of thermoplastic elastomers based on polyolefins, which can be used in the elastomer film layers, include, inter alia, a crystalline polyolefin, for example a homopolymer or a copolymer of an alpha-olefin having 1 to 20 carbon atoms, and comprising 1 to 12 carbon atoms.
The homopolymers and the copolymers described below are examples of crystalline polyolefins.
Alpha-olefins include, for example, ethylene, propylene, butene-1, 4-methyl-1pentene, 1-hexene, and 1-octene.
The polyolefin-based thermoplastic elastomers that are commercially available and intended to be used in the elastomer film layers include VISTAMAXX™ (propylene and/or ethylene-based elastomer, available from ExxonMobil Chemical, Houston, Tex.), INFUSE™ (olefin block copolymers, available from Dow Chemical Company, Midland, Michigan), VERSIFY™ (propylene/ethylene elastomer, in particular obtained via the technology “INSITE technology”) such as VERSIFY™ 4200 (Dow Chemical Company, Midland, Michigan), ENGAGE™ (ethylene octane copolymer, available from Dow Chemical, Houston, Tex.) and NOTIO 0040 and NOTIO 3560 (available from Mitsui Chemical (USA), New York, N.Y.), Adflex X100 G (available from Lyondellbasell). The following materials could also be used:
In a particularly suitable embodiment, the polyolefin-based thermoplastic elastomer is VISTAMAXX™ 6102FL or VISTAMAXX 7050 BF (available from ExxonMobil Chemical, Houston, Tex.). The reference “™” for registered trademarks corresponds to “Trade Mark”.
In another case, the thermoplastic elastomer may be a thermoplastic ester/ether elastomer.
“Elastomer material” means a material which can be stretched without breaking under the effect of a stretching force exerted according to a given direction, and which can substantially return to its initial shape and dimensions after this stretching force is relaxed. This is for example a film which retains a residual deformation or set following elongation and relaxation (residual deformation also referred to as “permanent set” or “SET”) that is less than or equal to 30%, preferably less than or equal to 20%, yet more preferably less than or equal to 10%, of the initial dimension thereof (prior to elongation) for an extension of 100% of the initial dimension thereof, at ambient temperature (23° C.—degrees Celsius). The elastomer material may be a thermoplastic elastomer material, in particular a physically cross-linked thermoplastic elastomer material, such as those described in the present disclosure, or a chemically cross-linked thermoplastic elastomer material.
In order to measure the rigidity of a nonwoven layer, it is possible in particular to use the following test:
The rigidity can be measured using a constant elongation rate of a traction rack under elongation, for example a constant rate of 508 mm/min, comprising a computer interface (an appropriate instrument is an MTS Alliance with TestWorks 4 software, available from the MTS Systems Corp company, Eden Prairie, Minnesota), equipped with a 5 N or 10 N or 100 N load cell. The tests are performed at 23° C.+−2° C. and at approximately 50% to +−2% relative humidity.
The rack comprises two lateral clamping jaws, for example made of stainless steel, defining therebetween a gap, and a plunge blade, made of a “lightweight” metal such as aluminium, which is arranged centrally, halfway between the jaws, above the gap. The sample is positioned such that two end parts of the region of a nonwoven layer, in which it is desired to study the rigidity of one point in the centre, are each clamped in one of the jaws, such that the point of the sample at which it is desired to measure the rigidity is located exactly below the plunge blade.
Samples measuring 50 mm in width and more than 40 mm in length are cut, in order to allow for testing of an inter-jaw length of 40 mm. If the element does not have sufficient material for samples of this size, the available dimensions are used to compare the rigidity of samples of the same dimensions. The plunge blade is lowered at a constant speed of 508 mm/min over a vertical distance of 40 mm, regulating the acquisition frequency to 100 Hz.
The software is programmed to calculate the maximum peak bending force, and the rigidity (N/m) of the formed curve giving the force (N) as a function of the elongation (m). The rigidity is calculated as being the gradient of the curve due to bending/elongation for the linear region of the curve, using a minimum line segment of at least 25% of the total peak bending force to calculate the gradient.
The tooling comprises a rectangular base 101 from which two low walls 102, 103 project laterally to the left and right, between which two front and rear rails 104, 105 extend in the form of rods. A trolley 106 is mounted such that it can slide along the two rails 104 and 105. Clamping means are provided, making it possible to lock the trolley 106 in a position of choice along the rails 104, 105. These means are controlled by a handle 107 which can be pivoted manually between a locking position in which the trolley 106 can no longer slide along the rails, and an unlocked position in which the trolley 106 can slide along the rails.
A movable jaw 108 is mounted on the top of the trolley 106, and a fixed jaw 109 is mounted on the top of the right-hand lateral low wall 103, the clamping of said jaws being able to be controlled by a clamping nut 111.
In order to support a rectangular laminate sample, for example of 30 mm by 30 mm, it is ensured that its two opposite edges in the direction CD are each held in one of the two movable 108 and fixed 109 jaws. Subsequently, the stretching (extension) which is intended to be applied to the sample is adjusted by releasing the handle 107 in order to thus cause the movable jaw 108 to slide. A slide 110 with markers makes it possible to know the value of the extension depending on the position of the movable jaw.
In order to measure the thickness of the sample of laminate S that is supported and stretched by the tooling 100 or an equivalent tooling, it is possible to use a pressure application and thickness measuring apparatus 200, as shown in
Said apparatus 200 comprises a disc 202, having a circular surface with a surface area of 25 cm2, arranged at the end of a cylindrical arm 203 that is movable vertically under the control of electronic control means integrated in the apparatus. The other end of the arm has an additional mass for applying a pressure of 1 KPa to a surface area of 25 cm2. In order to perform these measurements, a 15 mm×15 mm square pallet 201 is used, and thus the force applied to the sample is 11.1 kPa (11.1 kPa=1 kPa*(25 cm2/2.25 cm2)) and not 1 kPa. Thus, once the laminate is clamped between the pallet and the disc, it is possible to measure the thickness of the sample in the region of the surface of the pallet, by performing the following steps:
The sample is then positioned on the top of the 15×15 mm (2.25 cm2) pallet (i.e. 11.1 kPa=1 kPa*(25 cm2/2.25 cm2)), the 15×15 mm pallet being positioned in the axis of the cylindrical arm, and
In order to obtain the curve showing the relative loss of thickness as a function of elongation, the laminate is stretched to at least four stretching values, for example 25%, 50%, 75% and 100%, and, for each stretching value, the thickness, for example e25, e50, e75 et e100, is measured according to the method set out above, and the straight lines connecting the successive points, thus determined, are plotted, in order to obtain said curve.
The laminate of the prior art is an elastic laminate taken from a nappy having reference “02184499341631” from the pack of nappies with the Pampers® Baby-Dry™ trademark in size 4, and having reference “02184499 34 16:13 May 8, 2020 MADE in Germany E”. This product comprises an elastic film sandwiched between two nonwovens, said elastic film being fixed, by ultrasonic welding, in the stretched state to the two nonwovens.
In the present invention, maximum elongation of a laminate means the elongation in the direction CD, from which at least one undulation appears, in a cross-section of the laminate in the direction MD. In particular, in the present invention, the test is not carried out beyond 100% extension. The maximum loss of thickness is taken at 100%. The maximum extension is between 50% and 100%. If necessary, the maximum loss of thickness is taken at an elongation of 100%.
In
The intermediate laminate, formed of the first nonwoven layer NT1 and the two elastic films, is then transported towards a second lamination gap formed between two second lamination rollers 303, 304.
A second coating point, Coating 2, is arranged upstream of the second lamination gap and ensures the deposition on said intermediate laminate, from the die of the elastic films, of lines of glue, by means of a foil.
In addition, a second nonwoven layer NT2 passes into the second gap. Upstream of the second gap, the second nonwoven layer passes into a wave-formation gap, known as a waver, formed of two toothed rollers 305, 306, referred to as waver rollers, the teeth of which interpenetrate without contact in CD as shown in
In the embodiment in
The relative positions of the two waver rollers makes it possible to adjust the shape of the waves, in particular by unit of length and their height. The number of teeth of the two waver rollers makes it possible to adjust the number of waves.
The installation in
The installation in
In
Upstream of the gap and of each of the coating points, each respective nonwoven layer is passed into a wave-formation gap, known as a waver or tamper, formed of two toothed rollers, referred to as waver or tamper rollers, the teeth of which interpenetrate without contact in CD as shown in
In the installation in
In
Upstream of the gap and of one, here Coating 2, of the two coating points, the corresponding nonwoven layer, NT2, is passed into a wave-formation gap, known as a waver, formed of two toothed rollers, referred to as waver rollers, the teeth of which interpenetrate without contact in CD as shown in
According to an option of the installation in
The brake is defined by the presence of at least three successive slope variations, an initiation slope, a working slope, and a stop slope. The usage slope is of a lesser (positive) inclination, but not zero, than the (positive) inclination of the initiation and stop slopes.
In particular, according to the invention, the curve has an inflection point that separates a first lower curve segment having its concavity turned downwards, and a second upper curve segment having its concavity turned upwards. The first lower segment has a lower apex point, and the second upper segment has an upper apex point. The portion of the curve between the origin (coordinates F=0 for a percentage (%) of zero extension) and the lower apex point is the initiation segment of the curve, the portion of the curve between the lower apex point and the inflection point is the usage segment of the curve, and the portion of the curve between the inflection point and the upper apex point is the stop segment of the curve. It is possible to define the initiation slope as being the average slope of the initiation segment, the usage slope as being the average slope of the usage segment, and the stop slope as being the average slope of the stop segment.
In the case of the laminates of the prior art, there is no progressive counterreaction of the hand in the usage zone, and the user enters the stop zone directly, without any transition, such that they confuse it with the usage zone.
The usage slope according to the invention is preferably positioned before a 100% extension. The start of the usage region according to the invention is preferably positioned at a force greater than 2 N. The end of the usage region according to the invention is preferably positioned at a force of less than 10 N.
In particular, the X-axis of the initiation segment extends between 0% and a value of between 5% and 20%, for example 10%, and the X-axis of the usage segment extends between a value of between 5% and 20%, for example 10%, and a value of between 60% and 80%, for example 70%, while the X-axis of the stop segment extends, following the usage segment, up to a value of between 80% and 120%, in particular, as mentioned in the paragraph above, 100%.
Hereinafter, three examples of laminates according to the invention, denoted E46, E53 and HG1, respectively, are described.
The upper nonwoven is a nonwoven available from SANDLER under the reference SPUNLACE SAWASOFT 2925 at 30 g/m2. The elastic film formed, based on SIS, is extruded with an average basis weight of 50 g/m2, the lower nonwoven being a nonwoven available from FITESA under the reference SPUNBOND HES CD Rod with a basis weight of 20 g/m2. The structure of example 1 is as shown in
The upper nonwoven is a nonwoven available from SANDLER under the reference SPUNLACE SAWASOFT 2626 at 25 g/m2. The elastic film formed, based on SIS 50, is extruded with an average basis weight of 50 g/m2. The lower nonwoven is a nonwoven available from Texbond SPa under the reference SPUNBOND ULTRASOFT with a basis weight of 18 g/m2. The structure of example 2 is as shown in
Example 3: E53
Example 3 is similar to example 2, the difference being that the penetration airgap is in the region of 2.7 mm for example 3, instead of 2.8 mm for example 2.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR2111089 | Oct 2021 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/078871 | 10/17/2022 | WO |
