WO2014102683A1

WO2014102683A1 - Extensible laminar material

Info

Publication number: WO2014102683A1
Application number: PCT/IB2013/061180
Authority: WO
Inventors: Guido Bonelli
Original assignee: Fameccanica.Data S.P.A.
Priority date: 2012-12-28
Filing date: 2013-12-20
Publication date: 2014-07-03
Also published as: ITTO20121161A1

Abstract

Laminar material, elastically extensible along at least one direction (A), comprising an elastically extensible layer (106) coupled to at least one laminar layer (102, 104) extensible along at least the direction (A). The elastically extensible layer (106) is anchored to the laminar layer (102, 104) by means of adhesive lines (108) that extend in the direction orthogonal to the extension direction (A), and comprise a pigmented adhesive that is visible through the at least one extensible laminar layer (102, 104) and/or through the elastically extensible layer (106). The material is preferably produced in the form of a continuous strip, with the adhesive lines (108) extending in the direction of the longitudinal axis of the strip.

Description

"Extensible laminar material"

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TEXT OF THE DESCRIPTION

Field of the invention

The present invention refers to extensible laminar materials and has been developed with particular attention to the possible application for the production of absorbent sanitary articles, such as diapers for babies.

Description of the prior art

Wearable sanitary articles in pant-form are well known in the art, and typically comprise a central body or chassis capable of cupping around the groin portion (crotch portion) of the user with side panels that extend on opposite sides of at least one of the ends (front or rear) of the article in order to close the article itself along the waist line of the user.

In particular, sanitary articles of the type described above are known that comprise side panels having the characteristic of elastic extensibility.

The practical use of these known solutions, while having led to satisfactory results, has highlighted the fact that the extensible laminar material used to produce such side panels is capable of further improvements, in particular for that which concerns

- the simplicity of production,

- processability, intended as ease of processing in a production line for sanitary articles, and

- adaptability, intended as the adaptation of the elastic behavior as a function of the morphology and the tastes of the user.

For this purpose, elastically extensible laminar materials have been proposed, comprising an elastically extensible layer, for example an elastic polymer film, coupled to at least one extensible layer, for example, typically of nonwoven material, along the _· junction lines, for example adhesive lines. Layered materials are typically coupled together in non-extended conditions, and are then activated mechanically by extension of the laminar material, typically in a direction perpendicular to the direction of the junction lines. The subsequent return of said elastically extensible layer in a non-extended condition typically determines the retraction of the at least one extensible layer in a crinkling condition at least at the portions of said material not connected to the extensible layer along the junction lines, due to the fact that said non-extensible layer has undergone a permanent deformation, in particular an elongation in the extension direction. The laminar material thus formed is able to elastically extend at least in the direction of mechanical activation, and at the same time is soft and voluminous, thanks to the condition of crinkling generated by the activation itself. On the other hand, this type of material implies a greater complexity in its production, necessarily comprising a step of mechanical activation carried out by means of extension of the laminar material, both in its subsequent processing, for example in the use as raw material for the manufacture of absorbent articles, primarily because of its thickness, and of a possible lack of homogeneity of the mechanical and structural features .

Alternatively, elastically extensible laminar materials similar to those described above can be produced without the step of mechanical activation, and processed and used as such, for example being incorporated into an absorbent article, thereby obtaining a considerable simplification in the manufacture and in the subsequent processing of the material. In this case, the mechanical activation could be carried out in an automatic way, so to speak, for example when the material, incorporated in an absorbent article, is stretched at the moment of being worn. Alternatively, the material can be activated by the user, for example, before the article is worn. In both cases, however, such activation cannot be effectively controlled, in particular, the extent of the extension required and the localization of this activation are not easily determinable.

In various areas of application (in particular in the manufacture of wearable sanitary products in pant- form) the need has therefore arisen to provide extensible laminar materials that are not only achievable by means of relatively simple manufacturing processes, but that can also be incorporated, typically in the form of continuous strips, in a production line for sanitary articles with greater efficiency, and without the need for complex equipment for the transport and the guidance of said strips.

Moreover, in particular in the manufacture of diapers for babies or incontinence diapers for adults, the need has arisen for extensible materials that can have features of elastic behavior, adjustable to a certain extent by the user, so that the article has the best "fit", or rather is adapted to the morphology and the tastes of the user, making it comfortable but at the same time capable of achieving an optimal "tightness", without being loose or loosened to an extent that it would slide down in an undesired way.

Object and summary of the invention

The present invention aims to provide an extensible laminar material capable of satisfying the requirements outlined above, in an excellent way.

According to the invention, this object is achieved by a material having the features of claim 1.

The invention also relates to the corresponding method of manufacturing, as defined in claim 11.

The claims form an integral part of the technical disclosure provided here in relation to the invention Brief description of the designs

The invention will now be described, purely by way of non-limiting example, with reference to the accompanying drawings, wherein:

- Figure 1 is a general schematic view of a sanitary article, illustrated in an extended position, achievable with the use of an extensible laminar material of the type described;

- Figure 2 is a schematic section along the line IX-IX of Figure 1, of an extensible laminar material of the type described here, before activation by the user;

- Figure 3 is a section corresponding to that of Figure 2. of the same extensible laminar material in a released state after activation by the user;

- Figure 4 is a cross-section of a possible variant of the extensible laminar material described here, in a released state after activation by the user;

- Figure 5 is a plan view of an extensible laminar material before activation by the user;

- Figure 6 is a plan view of the material illustrated in Figure 5, illustrated in the extended configuration during the step of activation by the user .

Detailed description

In the following description, various specific details are illustrated aimed at a thorough understanding of the embodiments. The embodiments can be implemented without one or more of the specific details, or with other methods, components, materials, etc... In other cases, known structures, materials, or operations are not shown or described in detail to avoid obscuring various aspects of the embodiments.

The reference to "an embodiment" in the context of this description indicates that a particular configuration, structure or feature described in connection with the embodiment is included in at least one embodiment. Therefore, phrases such as "in an embodiment", possibly present in various places of this description, are not necessarily referring to the same embodiment. Furthermore, particular conformations, structures, or features may be combined in an appropriate way in one or more embodiments.

The references used herein are for convenience only and therefore do not define the field of protection or the scope of the embodiments.

In Figure 1, numeral 10 indicates, as a whole, a wearable sanitary product in pant-form, shown here in an extended flat position. It is, in the example illustrated here, an article (pant-diaper for children or incontinence diaper for adults) of the conventional type, intended to be sold opened and to be closed as a pant after being placed on the wearer's body. The solution described here is in any case capable of also being applied to the articles currently referred to as "training pants" intended to be sold already in the closed pant-configuration and to be slid onto the body of the user.

The product 10 illustrated here consists of a central body 12 intended to be applied onto the body of the user, conferring a general U-shaped conformation to it, by wrapping it around the crotch portion of the user .

The body or chassis 12 has a structure wherein the following features are usually recognizable (in addition to various other accessory elements) : - an upper layer or "topsheet" 13 permeable to evacuated body fluids, designed to be orientated towards the user's body;

- a lower layer or "backsheet" 14 impermeable to body fluids, designed to be orientated towards the outside, i.e. in the opposite position with respect to the body of the user; and

- an absorbent core 15, interposed between the topsheet 13 and the backsheet 14 .

Then there are elasticated side panels, indicated by the references 16, which extend from the central body 12, and allow (for example by means of adhesive tags 161 or microhooks) to close the article along the waist line so it can be worn by the user.

The side panels may be present at both ends (front and rear) of the central body 12. This is usually the case with articles such as "training pants", where the distal margins of the various panels are welded together to give the article the closed conformation, as sold. It is underlined that the connotation "front" and "rear" is used herein only to distinguish the two ends from each other, and therefore has no specific relevance regarding the manner in which the product„.is finally worn.

The- example of the embodiment illustrated here refers to the case (most frequently in the "open" sold products) wherein the side panels 16 are present at the rear end of the central body 12, while two wings 18 protrude laterally from the front end of the central body 12 conferring the typical hourglass shape to the article 10 (ideally seen in the open and extended position, as represented in Figure 1) .

The representation of Figure 1 is schematic in nature and is intended to highlight that the solution described here is capable of being applied to a wide variety of possible productive types of the article 10.

For a more detailed explanation of additional features of the article 10 (for example, regarding the presence of shaped edges - usually provided on the backsheet 14 of the product - and outlining the contour of the openings for the legs of the user and also for the presence of so-called "cuffs" or elasticated sides, arranged along the sides of the absorbent core 15, with the function of lateral containment of bodily fluids) there is extensive existing literature on the subject: this is also true in relation to the possible choice of the materials constituting the various parts of the article 10.

The side panels 16 can be produced from a material 100 in strip -or web- form, for example by referring to the solution described in detail in European patent application EP 1941853.

The present description refers primarily to a strip material and the relative production method.

In general, as illustrated in Figure 2, this material 100 has a layered or laminar structure, consisting of two external laminar layers 102, 104 - for example of nonwoven material - extensible along at least one direction A in a non-elastic manner, between which a layer 106 of material is interposed, elastically extensible along at least said direction A. The elastically extensible layer, or elastic layer, 106 is anchored to the two external laminar layers 102, 104 by adhesive lines 108 separate from each other and which extend in a direction essentially orthogonal to the at least one extension direction A. Typically, in a material 100 manufactured in the form of a continuous strip, the adhesive lines 108 extend parallel to the longitudinal extension of the strip, i.e. in a direction generally parallel to the longitudinal axis of the strip itself. The adhesive lines 108 comprise a pigmented adhesive material, so as to be visible through at least one of the external laminar layers 102 and 104, preferably through both laminar layers 102 and 104, and/or possibly also through the elastic layer 106

In other words, external laminar layers 102 and 104, and/or the elastic layer 106, are characterized by a degree of transparency so that the adhesive lines 108 comprising the pigmented adhesive material are clearly visible to the naked eye in the laminar material 100 of the present invention under normal conditions, for example typically when the perpendicular distance between the observer's eye and the plane of the laminar material 100 is about 30 cm.

The transparency of each laminated layer can also be defined in terms of transmittance, which as is known, represents the fraction of incident light that passes through a sample, and which can be measured with one of the methods known in the art. One method for determining the transmittance can be that described in patent application WO 2004/006818, assigned to The Procter & Gamble Company, in the paragraph entitled "Light transmittance (LT)". In a preferred embodiment, the transmittance of at least one of the external laminar layers 102 and 104, and/or of the elastic layer 106, can be at least 10%, preferably at least 45%, and ideally at least 85%.

The layers 102 and 104 can be comprised of carded (for example hydroentangled) nonwoven material, extensible in size in the selected direction, with a weight between 10 and 50 g/m², preferably between 15 and 25 g/m². Generally, in the production method of the material 100 of the present invention, the laminar layers 102, 104 are provided in the form of a continuous strip of non-woven material, extensible in the direction orthogonal to the axis of the strip (i.e., in the cross-machine direction, CD). Possible materials for the laminar layers 102 and 104 can be carded non-woven materials in commercially available 100% polypropylene of 25 g/m², produced by the company Sandler with the trade name of Sawatex® 11311DI52 or Sawatex® 22628, or non-woven material in 100% polypropylene of 25 g/m² also available from the company Sandler under the trade name Sawabond® 4159.

The elastic material 106 can be formed from the available material produced by the company Exten with the trade name Extretch 51, or by the company Nordenia with the trade name K6356, both are elastic polymeric films with a weight of about 45 g/m². The adhesive material can be formed by a commercially available hot melt-type adhesive, produced by the company Bostik under the trade name H20043, pigmented for example in blue .

The reference to these specific materials is purely illustrative and should not be interpreted in a limiting sense of the scope of the present description.

The layers of the laminar material 100, corresponding in the embodiment illustrated in Figure 2, to the two external laminar layers 102 and 104 extensible at least along a direction A, and to the elastic layer 106 interposed between them, are connected to each other by means of adhesive lines 108, in an extended state, i.e. without being subjected to tensile forces which could cause a substantial deformation, either temporary or permanent, and are consequently represented as being essentially flat and parallel between each other.

The laminar material 100 of the present invention is potentially capable of elastically extending at least along the said direction A, being susceptible to mechanical activation. With reference to Figure 1, this activation is carried out by subjecting the material to a tensile stress along the at least one extensibility direction A, typically in the two directions A, A' indicated by arrows. The two external laminar layers 102 and 104 are able to extend along this direction in a non-elastic manner, in other words, undergoing a permanent deformation, typically an elongation along said direction. In the typical case of laminar layers 102 and 104 made of non-woven material, this permanent deformation may typically correspond to a reorientation and displacement of the fibers constituting the material, usually with partial rupture of the existing bonds between the fibers. Generally such deformation can occur to a greater extent in the zones of the laminar layers 102 and 104 that are not affected by the adhesive lines 108. At the same time, the elastically extensible layer 106 is able to elastically stretch in the direction A of the traction. Obviously, the magnitude of the tensile stress will generally be proportional to the final elastic properties required for the laminar material 100, as well as to the physical features of the component materials, for example, typically the elongation breaking limits of the extensible laminar layers 102 and 104 and the elastic elongation limit of the elastic layer 106 .

Once the tensile stress has been removed, the extensible laminar material 100 contracts under the action of the elastic layer 106 and assumes the transverse profile visible in Figure 3, where the retraction of the layers 102 and 104 determines the crinkling in the zones between the adhesive lines 108. The laminar material 100 is able to elastically extend and retract, at least in the direction A, and the crinkled transverse profile increases its thickness and softness, typically appreciated in the use in sanitary articles, where said laminar material 100 is designed to enter into contact with the user' s skin, for example in the case of the sanitary article 10 illustrated in Figure 1.

It is clear to the expert in the field that nothing changes, from a technological point of view, if the material 100 is produced with the laminar layer 102 wider than the 104, or vice versa.

In a different embodiment of the present invention, the extensible laminar material 100' can be formed by a single laminar layer 102 extensible along at least one direction A in a non-elastic manner coupled to an elastically extensible layer 106 by means of adhesive lines 108 extending in a direction essentially orthogonal to the direction A. Figure 4 illustrates a laminar material 100' elastically extensible in a non-expanded condition after the mechanical activation step, with the laminar layer 102 in a condition of crinkling.

The laminar material 100, 100' of the present invention, in principle, may be subjected to the mechanical activation step, by means known in the art, during a further step of processing subsequent to its formation, and then being stored as already activated extensible laminar material. Alternatively, the extensible laminar material 100, 100' can be fed as such to a production line of an article such as the sanitary product 10 illustrated in Figure 1, and subjected to in-line mechanical activation.

More typically, the material of the present invention can advantageously be applied, as it stands, to a sanitary product, or rather without being subjected to any form of mechanical activation, neither before nor after its incorporation into the article, for example to form elasticized side panels such as the ones indicated by references 16 in Figure 1. The material 100, 100' can then be mechanically activated directly by the user, in order to obtain the required elastic features.

The extensible material 100, 100' of the present invention has the adhesive lines 108 comprising a pigmented adhesive material that is visible through at least one of the laminar layers 102, 104, or through both, or also through the elastically extensible layer 106, as may be preferable in the case of an extensible laminar material 100' comprising only one laminar layer 102 coupled to the elastic layer 106, such as that illustrated in Figure 4, so that, in general, the pigmented adhesive material is preferably visible from both sides of the laminar material 100, 100' . As is clear to the skilled person, the pigmented adhesive material will be visible as a series of colored bands 108' through at least one of the layers 102, 104, 106, as shown schematically in Figure 5, where the colored bands 108' corresponding to the pigmented material of the adhesive lines 108, visible, for example, through the laminar material 102, are represented by shades of gray. Correspondingly, the areas 110 of the laminar material 100, 100' comprised between said colored bands 108' generally appear as the color of the materials composing the laminar material 100, 100' , for example typically white or translucent. Figure 5 can represent, for example, the material 100 illustrated in Figure 1, from the point of view of an observer looking from the side of the laminar material 102.

The laminar material 100, 100' can typically be incorporated into an article, for example the sanitary article 10 of Figure 1 where the laminar material 100, 100' forms the side panels 16, and in order to produce the mechanical activation, in such a way as to confer elasticity to the side panels 16, the user may grasp each side panel 16 from the two side ends, for example the free end where the tag 161 is found, and the end connected to the central body 12, and subjecting the side panel 16 to traction along the direction A, in two opposite directions A, A' indicated by arrows, generally orthogonal to the adhesive lines 108. As shown in Figures 5 and 6, the colored bands 108', corresponding to the adhesive lines 108, visible through one of the laminar layers, for example the layer 102, and, generally to a greater extent, the non- colored areas 110 between them, typically white or translucent, widen during the traction, as highlighted for example by comparing the widths 112, 114 and, respectively, 116, 118 in Figures 5 and 6, and they provide the user with a convenient visual reference of the extent and homogeneity of the traction, and then ultimately of the elasticity conferred to the laminar material 100, 100', i.e. to the side panel 16, obviously within the limits of the physical features of elongation of the various component materials of the laminar material 100, as previously explained. As easily deducible, a greater width 116, 118 of the colored bands 108' and, more significantly, of the non- colored areas 110 between them during the traction, i.e. typically at the act of mechanical activation by the user, corresponds to a greater elongation of the laminar material 100, 100' under the tensile stress, and then ultimately typically to a greater extensibility of the elastic type after the mechanical activation, that is, once the tensile stress is released and the laminar material 100, 100' is once again in an extended and crinkled state. Therefore the user can easily, and in a repeatable manner, confer a required elastic characteristic to the side panels 16 of the absorbent articles 10, compatible with their needs, for example to obtain a better fit of the absorbent article in order to adapt it to the size of the person intended to wear it. The course of these colored bands 108' and non-colored areas 110 during the mechanical activation can provide additional guidance to the user, as a generally straight and parallel course of said colored bands 108' and non-colored areas 110 may be indicative of a uniform and homogeneous tensile stress, resulting in improved elastic features of the laminar material.

The presence of the adhesive lines 108 comprising a pigmented material visible through a laminar layer 102, 104 and/or the elastically extensible layer 106 in the material 100, 100' produced in the form of a continuous strip confers a further advantage for the production of subsequent in-line processing of the same material, for example, in order to incorporate the material into a sanitary article such as that illustrated in Figure 1, in a production line of the same. The correct positioning of the strip in the processing line can in fact be effectively managed with greater precision by means of a piece of control apparatus coupled to a vision system, known per se in the art, able to easily detect the pigmented adhesive lines comprised in the laminar material, and then, accordingly, to control the positioning of the strip, allowing, among other things, the in-line processing of strips of material 100, 100' of reduced width .

The adhesive lines 108 of the laminar material 100, 100' of the present invention can be produced with one of the methods known in the art, for example contact methods such as coating, or non-contact methods such as extrusion.

According to the present invention, the adhesive lines 108 in the laminar material 100, 100' may have a width 112 of between 0.1 and 5 mm, preferably between 0.5 and 2 mm.

In general, the adhesive lines 108 in the material 100, 100' of the present invention can be separated by a distance 114 of between 1 and 10 mm, preferably between 1 and 6 mm, and ideally between 2 and 4 mm. Generally, it may be preferable that the width 112 of the adhesive lines 108 of the material 100, 100' is less than the distance 114 that separates them.

As can be deduced, in a material 100, 100' according to the present invention, the smaller the distance 112 that separates the adhesive lines 108, the thinner the resulting material will be, subsequent to a step of mechanical activation, since the crinkling induced in the laminar layer 102, 104 will be proportionally less pronounced, with obvious advantages in the case that the material 100, 100' in the form of a continuous strip has to be subjected to further inline processing steps, but also in the case wherein the mechanical activation is made by the user in the context of an already-formed sanitary article, as described above, as the material 100, 100' will present a more uniform and "smooth" appearance, while still presenting the required fluffiness and softness.

In general, the material 100, 100' of the present invention can present adhesive lines 108 all having the same width. In one embodiment of the present invention, the material 100, 100' , typically produced in the form of a continuous strip, with the adhesive lines 108 extending essentially parallel to the longitudinal axis of the strip itself, can comprise several adhesive lines having a greater width than the others, particularly in the zones less susceptible to mechanical activation, in order to ensure greater stability of the laminar structure of the material 100, 100' , for example to reduce the possibility of accidental delamination during use or further processing. For example, in a particular embodiment, a material 100, 100' in the form of a continuous strip can have two wider outer adhesive lines, adjacent to the longitudinal side edges of the strip, compared to the other adhesive lines 108 comprised between them. In these areas near the edges, the elastic properties that can be conferred by the mechanical activation are typically less pronounced, and less necessary, than in the intermediate area of the material 100, 100' between them, but the connection between the components of the laminar structure is greater so that it is able to confer enhanced stability to the material. For example this material could be used in the production of the side panels 16 in a sanitary article 10 such as that illustrated in Figure 1, with the zones characterized by adhesive strips wider at the distal edges of the panels, where the tags 161 are positioned, and of the proximal edges, where the panels 16 are joined to the main body 12. A method for producing a material 100, 100' according to the present invention, elastically extensible along at least one direction A comprises the steps of providing an elastically extensible layer 106 in a non-expanded condition, typically in the form of a continuous strip; providing at least one laminar layer 102, 104, extensible along at least the direction A in a non-elastic manner, in a non-expanded condition, typically in the form of a continuous extensible strip in the direction orthogonal to the axis of the strip (i.e., in the cross-machine direction, CD); anchoring the elastically extensible layer 106 to the at least one laminar layer 102, 104 through adhesive lines 108 separate between each other and extending in a direction essentially orthogonal to the extension direction, that is, typically, extending in a direction parallel to the axis of the strip materials 106, 102, 104; the adhesive lines 108 being formed of a pigmented adhesive material, so as to be visible through at least one laminar layer 102, 104, and/or also through the elastically extensible layer 106. The width 112 of the adhesive lines 108 and the spacing 114 between them are selected as explained above.

Of course, without prejudice to the principle of the invention, the details of construction and the embodiments may vary widely with respect to those described and illustrated without departing from the scope of the invention as defined by the claims that follow.

Claims

1. Laminar material (100, 100') elastically extensible along at least one direction (A) , comprising an elastically extensible layer (106) coupled to at least one laminar layer (102, 104) extensible along at least said direction (A) ,

said elastically extensible layer (106) being anchored to said at least one laminar layer (102, 104) by adhesive lines (108) separated from each other, extending in a direction essentially orthogonal to said direction (A) ,

said adhesive lines (108) comprising a pigmented adhesive material, so as to be visible through said at least one laminar layer (102, 104) and/or said elastically extensible layer (106).

2. Material according to claim 1, presenting a sandwich structure with said elastically extensible layer (106) interposed between two of said laminar layers (102, 104) .

3. Material according to claim 2, wherein said adhesive lines (108) are present on both sides of said elastically extensible layer (106) determining the anchoring with respect to both said two laminar layers (102, 104).

4. Material according to any one of the preceding claims, wherein said adhesive lines (108) have a width (112) of between 0.1 and 5 mm, preferably between 0.5 and 2 mm.

5. Material according to any one of the preceding claims, wherein said adhesive lines (108) are separated by a distance (114) between 1 and 10 mm, preferably between 1 and 6 mm, ideally between 2 and 4 mm.

6. Material according to any one of the preceding claims, wherein the width (112) of said adhesive lines (108) is less than the distance (114) that separates them.

7. Material according to any one of the preceding claims, wherein said elastically extensible layer (106) is formed from an elastic polymeric film.

8. Material according to any one of the preceding claims, wherein said at least one laminar layer (102, 104) is formed from a non-woven material.

9. Material according to any one of the preceding claims, wherein said pigmented adhesive material is made of a thermo-fusible glue.

10. Material (100, 100') according to any one of the preceding claims, in the form of an strip extensible along said direction (A) transversely to the longitudinal extension of the strip, wherein said adhesive lines (108) extend parallel to the longitudinal extension of said strip.

11. Method for producing a laminar material (100, 100' ) elastically extensible along at least one direction (A) comprising the steps of:

- providing an elastically extensible layer (106) in a non-extended condition,

- providing . at least one laminar layer (102, 104), extensible along at least said direction (A) in a non- extended condition,

anchoring said elastically extensible layer (106) to said at least one laminar layer (102, 104) with adhesive lines (108) separated from each other and extending in a direction essentially orthogonal to said direction (A), said adhesive lines (108) comprising a pigmented adhesive material.

12. Method according to claim 11, wherein said adhesive lines (108) have a width (112) of between 0.1 and 5 mm, preferably between 0.5 and 2 mm.

13. Method according to claim 11 or claim 12, wherein said adhesive lines (108) are separated by a distance (114) between 1 and 10 mm, preferably between 1 and 6 mm, ideally between 2 and 4 mm.

14. Use of an extensible material (100, 100') according to any one of claims 1 to 10 for the production of sanitary articles.