ITTO20121161A1 - EXTENDIBLE LAMINAR MATERIAL - Google Patents

Description

DESCRIPTION

"Expandable laminar material"

Field of the invention

The present invention refers to extendable laminar materials and has been developed with particular attention to the possible application for the production of absorbent sanitary articles, for example baby diapers.

Description of the related technique

Wearable sanitary ware in the form of a panty are well known in the art, and typically comprise a central body or chassis capable of being arranged in a concave shape around the crotch portion of the user with side panels or side panels extending on opposite sides of at least one of the ends (front or rear) of the article so as to be able to close the article itself along the user's lifeline.

In particular, sanitary articles of the type described above are known which 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 extendable laminar material used to make these side panels is susceptible of further improvements, in particular as regards

- the simplicity of implementation,

processability, understood as ease of processing in a production line for sanitary items, e

adaptability, understood as adaptation of the elastic behavior according to the morphology and tastes of the user.

For this purpose, elastically extensible laminar materials have been proposed comprising an elastically extensible layer, for example an elastic polymeric film, coupled to at least one extensible layer, for example typically a nonwoven, along seams, for example lines of adhesive. The layered materials are typically coupled together in a non-extended condition, and are then mechanically activated by extending the laminar material, typically in a direction perpendicular to the direction of the seams. The subsequent return of said elastically extensible layer to a non-extended condition typically causes the at least one extensible layer to be returned to a wrinkled condition at least in correspondence with the portions of said material not connected to the extensible layer along the seams, due to the fact that said non-extendable layer has undergone a permanent deformation, in particular an elongation in the direction of extension. The laminar material thus formed is able to extend elastically at least in the direction of mechanical activation, and at the same time is soft and bulky, thanks to the wrinkling condition generated by the activation itself. On the other hand, such a type of material implies greater complexity both in its realization, necessarily including a mechanical activation step carried out by extending the laminar material, and in each subsequent processing thereof, for example in its use as a raw material for the manufacturing of absorbent articles, mainly due to its thickness and a possible lack of homogeneity of mechanical and structural characteristics.

Alternatively, elastically extendable laminar materials similar to those described above can be produced without the mechanical activation step, and processed and used as such, for example by being incorporated into an absorbent article, thereby obtaining a considerable simplification in manufacturing and subsequent processing. of the material. In this case the mechanical activation could take place in a so to speak automatic way, when for example the maternal, incorporated in an absorbent article, is ironed 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 necessary extension and the location of such activation are not easily determined.

In various sectors of application (in particular in the production of wearable sanitary products like panties) there is therefore a need to have extensible laminar materials that are not only achievable through relatively simple production processes, but that can also be incorporated, typically in the form of continuous belts, in a production line for hygienic-sanitary articles with greater efficiency, and without the need for complex apparatuses for transporting and guiding said belts.

Furthermore, in particular in the production of diapers for children or cloths for incontinent adults, the need is felt for extensible materials that can have elastic behavior characteristics that can be adjusted to a certain extent by the user, so that the article has the best " wearability ", that is to say it adapts to the morphology and tastes of the user, resulting comfortable but at the same time capable of achieving an optimal" hold ", without being slack or loose to such an extent as to slide down in an undesirable way.

Purpose 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 characteristics of claim 1.

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

The claims form an integral part of the technical teaching administered herein in relation to the invention.

Brief description of the drawings

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

- figure 1 is a general schematic view of a sanitary article, illustrated in an extended position, which can be made with the use of an extendable laminar material of the type described;

Figure 2 is a schematic section along line IX-IX of Figure 1, of an extendable 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 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 extendable laminar material prior to activation by the user;

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

Detailed description

The following description illustrates various specific details aimed at an in-depth understanding of the embodiments. The embodiments can be made 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 making various aspects of the embodiments are obscure.

Reference to "an embodiment" within this description means that a particular configuration, structure or feature described in relation to the embodiment is included in at least one embodiment. Therefore, phrases such as "in one embodiment", possibly present in different places of this description, are not necessarily referred to the same embodiment. Furthermore, particular conformations, structures or features can be suitably combined in one or more embodiments.

The references used here are for convenience only and therefore do not define the scope of protection or the scope of the forms of implementation.

In Figure 1, the numerical reference 10 indicates as a whole a sanitary product that can be worn in the form of a panty, shown here in a flat lying position. In the example illustrated herein, this is an article (baby panty or incontinent adult diaper) of a conventional type, intended to be sold open and to be closed into a panty after being placed on the user's body. The solution described here can in any case also be applied to articles currently called "training pant" intended to be sold already closed in the panty configuration and to be slipped onto the user's body.

The product 10 illustrated here consists of a central body 12 intended to be applied to the user's body, giving it a general U-shape by wrapping it around the crotch portion of the user.

The body or chassis 12 has a structure in which they are usually recognizable (in addition to various other accessory elements):

- an upper layer or "topsheet" 13 permeable to evacuated body fluids, intended to be turned towards the user's body;

- a lower layer or "backsheet" 14 impermeable to body fluids, intended to be facing outwards, ie in an opposite position with respect to the user's body; And

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

There are also elastic side panels ("side panels"), indicated with the references 16, which extend from the central body 12, and allow (for example through adhesive labels 161 or micro-hooks) to close the article along the lifeline as follows as worn by the user.

The side panels can be present at both ends (front and rear) of the central body 12. This is usually the case of articles of the "traininq pant" type, where the distal edges of the various panels are welded together to give the article as sold the closed conformation. It should be emphasized that the connotation "front" and "rear" is used here only to distinguish the two ends from each other and therefore has no specific relevance as regards the manner in which the product is finally worn.

The embodiment example illustrated here refers to the case (more frequent in "open" products sold) in which the side panels 16 are present at the rear end of the central body 12, while two fins 18 protrude laterally from the front end of the body central 12 giving article 10 (ideally seen in an open and extended position, as shown in Figure 1) the typical hourglass shape.

The representation of figure 1 is schematic in nature and intends to highlight that the solution described here can be applied to a wide variety of possible embodiments of article 10.

For a more detailed illustration of further characteristics of article 10 (for example, as regards the presence of shaped edges - usually provided on the backsheet 14 of the product - and outlining the outline of the openings for the user's legs and again for the presence of so-called "cuff" or elasticized sides arranged along the sides of the absorbent core 15 with the function of lateral containment of body flows) refers to the extensive literature on the subject: this also applies in relation to the possible choice of the materials making up the various parts of article 10.

The side panels 16 can be obtained starting from a material 100 in the form of a tape or web, for example by resorting to the solution described in detail in the European patent application EP 1941853.

The present description mainly refers to a strip material and the related production process.

In general, as illustrated in Figure 2, this material 100 has a stratified or laminar structure consisting of two external laminar layers 102, 104 - for example of non-woven fabric (nonwoven) - extendable along at least one direction A in a non-elastic way , between which a layer 106 of elastically extensible material is interposed 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 separated from each other and extending in a direction substantially orthogonal to at least one direction of extension A. Typically, in a material 100 made in the form of a continuous tape, the adhesive lines 108 extend parallel to the longitudinal extension of the tape, i.e. in a direction generally parallel to the longitudinal axis of the tape itself. The adhesive lines 108 comprise a pigmented adhesive material, so as to be visible through at least one of the outer laminar layers 102 and 104, preferably through both the laminar layers 102 and 104, and / or possibly also through the elastic layer 106.

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

The transparency of each laminar 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. A 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 outer laminar layers 102 and 104, and / or of the elastic layer 106, can be at least 10%, preferably at least 45%, and more preferably at least 1 ' 85%.

The layers 102 and 104 can be constituted by carded non-woven fabric, for example carded bonded to water (hydroentangled), which can be extended to the extent and in the selected direction, with a weight of between 10 and 50 g / m <2>, preferably between 15 and 25 g / m <2>. Generally, in the production process of the material 100 of the present invention, the laminar layers 102, 104 are provided in the form of a continuous web of non-woven fabric extensible in a direction orthogonal to the axis of the web (ie, in cross-machine direction, CD). Possible materials for the laminar layers 102 and 104 can be carded non-woven fabrics in 100% polypropylene of 25 g / m <2> commercially available in the production of the Sandler company under the trade name of Sawatex® 11311DI52 or Sawatex® 22628, or the non-woven fabric in 100% polypropylene of 25 g / m <2> also available from the Sandler company under the trade name Sawabond® 4159.

The elastic material 106 can be constituted by the material available in the production of the Exten company with the commercial name Extretch 51, or of the Nordenia company with the commercial name K6356, both are elastic polymeric films with a grammage of about 45 g / m <2>. The adhesive material can consist of a hot melt type adhesive commercially available in the production of the Bostik company under the trade name H20043, pigmented for example in blue.

The reference to these specific materials is purely illustrative and must 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 extendable at least along a direction A, and to the elastic layer 106 interposed between them, are connected to each other, by means of the lines of adhesive 108, in an extended condition, that is without being subjected to traction forces which could cause a substantial deformation, whether temporary or permanent, and are consequently shown substantially flat and parallel to 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 direction of extensibility A, typically in the two directions A, A 'indicated by the arrows. The two external laminar layers 102 and 104 are able to extend along this direction in a non-elastic way, 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 fabric, this permanent deformation can typically correspond to a reorientation and displacement of the fibers constituting the material, generally with partial breaking of the bonds existing between the fibers. Generally, this deformation can occur to a greater extent in correspondence with the areas of the laminar layers 102 and 104 not affected by the adhesive lines 108. At the same time, the elastically extensible layer 106 is capable of elastically elongating in the direction A of traction. Obviously, the entity of the tensile stress will generally be commensurate with the final elastic properties desired for the laminar material 100, as well as with the physical characteristics of the component materials, for example typically the elongation at break 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 shrinkage of the layers 102 and 104 causes them to wrinkle in the areas comprised between the adhesive lines 108. The laminar material 100 is capable of elastically extending and retracting, at least in the direction A, and the crimped transverse profile increases its thickness and softness, typically appreciated in use in sanitary articles, where said laminar material 100 is intended to come into contact with the skin of the user, as for example in the case of the sanitary article 10 illustrated in Figure 1.

It is evident that for the skilled in the art nothing changes from a technological point of view, if the material 100 is produced with the laminar layer 102 wider than 104, or vice versa.

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

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

More typically, the material of the present invention can be advantageously applied as such to a sanitary product, i.e. without being subjected to any form of mechanical activation either before or after its incorporation into the article, for example to form elasticized side panels such as those indicated with the references 16 in Figure 1. The material 100, 100 'can therefore be mechanically activated directly by the user, so as to obtain the desired elastic characteristics.

The extensible material 100, 100 'of the present invention has the adhesive lines 108 comprising a pigmented adhesive material which is visible through at least one of the laminar layers 102, 104, or through both, or even through the elastically extensible layer 106, as could be be preferable in the case of an extensible laminar material 100 'comprising only a 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 will be 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 schematized in figure 5, where the colored bands 108' corresponding to the pigmented material of the lines adhesive 108, visible through for example 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' will generally appear in the color of the materials composing the laminar material 100, 100 ', for example typically white or translucent. Figure 5 may 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 in an article, for example the hygienic-sanitary article 10 of Figure 1 where the laminar material 100, 100' forms the side panels 16, and in order to carry out their mechanical activation, in so as to give elasticity characteristics to the side panels 16, the user can grasp each side panel 16 from the two lateral ends, for example the free end where the label 161 is located and the end connected to the central body 12, and subject the side panel 16 to traction along the direction A, in the two opposite directions A, A 'indicated by the arrows, generally orthogonal to the adhesive lines 108. As shown schematically 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, to a generally greater extent, the non-colored areas 110 between them, typically white or translucent, widens during traction, as evidenced for example by comparing the widths 112, 114 and 116, 118 respectively in Figures 5 and 6, and provide the user with a convenient visual reference of the amount and homogeneity of the traction, and therefore ultimately of the 'elasticity conferred to the laminar material 100, 100', that is to the side panel 16, obviously within the limits of the physical characteristics of elongation of the various materials making up the laminar material 100, as explained above. As can be easily understood, a greater width 116, 118 of the colored bands 108 'and, more significantly, of the non-colored areas 110 between them during traction, i.e. typically upon mechanical activation by the user, corresponds to a greater elongation of the laminar material 100, 100 'under the tensile stress, and therefore ultimately typically to a greater elastic-type extensibility after mechanical activation, i.e. once the tensile stress has been released and the laminar material 100, 100 is brought back 'to a relaxed, rippling condition. Therefore the user can easily, and in a repeatable manner, confer a desired elastic characteristic to the side panels 16 of the absorbent articles 10, commensurate with his needs, for example to obtain a better fit of the absorbent article by adapting it to the size of the person intended to wear it. . The pattern of said colored bands 108 'and non-colored areas 110 during mechanical activation can provide further indications to the user, since a generally straight and parallel pattern of said colored bands 108' and non-colored areas 110 can be indicative of a uniform and homogeneous tensile stress, resulting in improved elastic characteristics 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 'made in the form of a continuous tape confers a further advantage for carrying out subsequent processing in line of the material itself, for example, in order to incorporate the material in a sanitary article such as the one illustrated in Figure 1, in a production line of the same. The correct positioning of the tape in the processing line can in fact be carried out effectively and with greater precision by means of a control apparatus enslaved to a vision system, per se known in the art, capable of easily detecting the lines of pigmented adhesive included in the laminar material, and therefore consequently 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 made with one of the methods known in the art, for example contact methods such as spreading, or non-contact methods such as extrusion.

According to the present invention, the adhesive lines 108 in the laminar material 100, 100 'can have a width 112 comprised 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 comprised between 1 and 10 mm, preferably between 1 and 6 mm, and more preferably between 2 and 4 mm. It may generally be preferable that the width 112 of the adhesive lines 108 of the material 100, 100 'is less than the distance 114 which separates them.

As can be understood, in a material 100, 100 'according to the present invention, the shorter the distance 112 that separates the adhesive lines 108, the less often the resulting material will be after a mechanical activation step, since the wrinkle induced in the laminar layer 102, 104 will be proportionally less pronounced, with obvious advantages in the case the material 100, 100 'in the form of a continuous strip has to be subjected to further processing steps in line, but also in the case in which the mechanical activation is carried out by the user in the context of an already formed sanitary article, as described above, since the material 100, 100 'will have a more uniform and "smooth" appearance, while presenting the desired softness and softness.

In general, the material 100, 100 'of the present invention can have adhesive lines 108 all having the same width. In an embodiment of the present invention, the material 100, 100 ', typically made in the form of a continuous tape, with the adhesive lines 108 extending substantially parallel to the longitudinal axis of the tape itself, can comprise some adhesive lines having a width greater than the others, particularly in areas 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 tape can have the two outermost adhesive lines, adjacent to the longitudinal side edges of the tape, wider than the other adhesive lines 108 between them. In such areas close to the edges the elastic properties that can be conferred by 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 and this is able to confer an improved stability to the material. For example, such a material could be used in the realization of the side panels 16 in a hygienic-sanitary article 10 such as the one illustrated in Figure 1, with the areas characterized by wider adhesive strips at the distal edges of the panels, where the labels are positioned. 161, and of the proximal edges, where the panels 16 are joined to the central body 12. A process for making 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-extended condition, typically in the form of a continuous web; provide at least one laminar layer 102, 104, extensible along at least direction A in a non-elastic way, in a non-extended condition, typically in the form of a continuous web extensible in a direction orthogonal to the axis of the web (i.e., in cross-machine direction, CD); anchoring the elastically extensible layer 106 to the at least one laminar layer 102, 104 by means of adhesive lines 108 separated from each other and extending in a direction substantially orthogonal to the direction of extension A, i.e., typically, extending in a direction parallel to the axis of the web materials 106 , 102, 104; the adhesive lines 108 being made of a pigmented adhesive material, so as to be visible through at least one laminar layer 102, 104, and / or also through the elastically extendable layer 106. The width 112 of the adhesive lines 108 and the spacing 114 between them are selected as shown above.

Naturally, the principle of the invention remaining the same, the details of construction and the embodiments may be widely varied with respect to those described and illustrated without thereby departing from the scope of the invention as defined by the following claims.

Claims (14)

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 substantially orthogonal to said direction (A), said adhesive lines (108) comprising a material pigmented adhesive, so as to be visible through said at least one laminar layer (102, 104) and / or said elastically extendable layer (106). 2. Material according to claim 1, having 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 its 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) comprised between 0.1 and 5 mm, preferably comprised 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, more preferably 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) which separates them. A material according to any one of the preceding claims, wherein said elastically extensible layer (106) is constituted by an elastic polymeric film. 8. Material according to any one of the preceding claims, wherein said at least one laminar layer (102, 104) is constituted by a non-woven fabric. 9. Material according to any one of the preceding claims, wherein said piqmented adhesive material is constituted by a thermo-fusible glue. 10. Material (100, 100 ') according to any one of the preceding claims, in the form of a tape extendable along said direction (A) transversely to the longitudinal extension of the tape, in which said adhesive lines (108) extend parallel to the extension longitudinal length of said belt. 11. Process for making a laminar material (100, 100 ') elastically extensible along at least one direction (A) comprising the operations of: providing a resiliently 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 substantially orthogonal to said direction (A), said adhesive lines (108) comprising a material pigmented adhesive. 12. Process according to claim 11, wherein said adhesive lines (108) have a width (112) comprised between 0.1 and 5 mm, preferably comprised between 0.5 and 2 mm. 13. Process 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, more preferably between 2 and 4 mm. Use of an extensible material (100, 100 ') according to any one of claims 1 to 10 for making sanitary articles.