DE102019130246A1 - Elastic laminate and process for producing the elastic laminate - Google Patents

Abstract

The invention relates to an elastic laminate with two nonwoven layers (1) forming opposite outer sides and with strips (2) of an elastic film which run in a stretching direction (D) and are integrated between the nonwoven layers (1), the strips (2) are bound under tension between the nonwoven layers (1) and the nonwoven layers (1) are folded in a relaxed state by the restoring forces of the strips (2) bound under tension along the stretching direction (D) and the strips are transverse to the direction of expansion (D) along a transverse direction (Q) are arranged at a distance from one another and wherein the width (q) of the strips (2), determined perpendicular to the direction of expansion (D) along the transverse direction (Q), is between 3 mm and 15 mm is. According to the invention, the nonwoven layers (1) are connected to one another and / or to the strips (2) of the elastic film at discrete adhesive-free connection points (3).

Description

The invention relates to an elastic laminate, a method for producing the elastic laminate and a disposable diaper formed with the elastic laminate.

The elastic laminate is particularly suitable for disposable articles from the hygiene sector such as disposable diapers, disposable pants or disposable incontinence products for adults. With these products, on the one hand, there is a need for a simple, inexpensive and resource-saving construction, on the other hand a good and reliable fit is necessary. For this purpose, elastic regions, for example diaper ears, waist bands or the like, can be formed with the elastic laminate. It can also be used for certain medical applications such as bandages or heat belts. If reference is made in particular to diapers below, this application is to be regarded as exemplary.

Diapers, especially for babies and toddlers, are produced as single-use, mass-produced articles, so that there are special requirements for efficient material use and low production costs.

In addition, however, a large degree of functionality is also necessary at the same time, so that a high degree of safety and reliable protection of the person wearing the diaper are ensured under all operating conditions. Large quantities of excrement have to be absorbed and safely retained overnight, while avoiding any damage to the skin of a wearer. Disposable diapers are therefore provided with elastic elements and sections to seal the waist and legs of a user. At the same time, a high level of comfort must also be ensured when the user moves. In particular, constrictions and skin irritation due to the elastic sections and elements are to be avoided.

In order to form elastic side parts and in particular lateral diaper closures, elastic laminates are known which have layers of nonwoven on their opposite outer sides and an elastic core in between. According to the prior art, the elastic core can be formed, for example, by an elastic film which is integrated over the entire surface or else by elastic strands.

The present invention is based specifically on an elastic laminate, in particular for diaper closures, which consists of the EP 3 228 292 A1 is known. The elastic laminate comprises two nonwoven layers forming opposing outer sides and strips of an elastic film which run in a stretching direction and are bound in between the nonwoven layers, the strips being bound under tension between the nonwoven layers and the nonwoven layers being relaxed in a relaxed state the restoring forces of the pre-tensioned strips are pleated along the direction of stretch and the strips are arranged at a distance from one another transversely to the direction of stretch along a transverse direction and the width of the strips determined between 3 mm and 15 mm perpendicular to the direction of stretch along the transverse direction is.

By specifying the strip width of 3 mm to 15 mm, it also becomes clear that typical sections of the laminate for forming elastic functional elements, such as diaper ears, each have a plurality of strips running side by side. The elastic properties of such a blank are then provided jointly by all of the strips.

In order to be able to form the elastic laminate in accordance with the generic state of the art and in particular to incorporate the elastic strips, an adhesive is provided which preferably itself has elastic properties, so that the elastic properties caused by the strips of the elastic film are not excessively impaired by the bonding .

Even if that from the EP 3 228 292 A1 known laminate has good functional properties, there are certain disadvantages, particularly with regard to the production. When using adhesive, undesirable solvents, plasticizers or similar additives are often necessary. Since the elastic strips are glued to the nonwoven layers in the stretched state, a comparatively fast-curing adhesive must generally also be provided in order to avoid that only the elastic strips contract without the nonwoven layers not yet adequately attached to them. The material must therefore be kept under tension for a certain distance during production or the web speed must not exceed a certain value. These aspects usually do not play a special role in an essentially tension-free lamination.

The present invention has for its object to provide a generic elastic laminate, which is characterized by good functional properties, is simple in structure and can be manufactured efficiently. Furthermore, a Methods for producing the elastic laminate and a disposable diaper formed with the laminate can be specified.

The object of the invention and the solution to the problem are an elastic laminate according to claim 1, a method for producing the elastic laminate according to claim 18 and a disposable diaper according to claim 20.

With regard to the elastic laminate itself, starting from a generic design, it is provided that the nonwoven layers are connected to one another and / or to the strips of the elastic film at discrete adhesive-free connection points.

According to a preferred embodiment of the invention, the discrete adhesive-free connection points can be designed as ultrasonic welding points.

Surprisingly, it is also possible, particularly by ultrasonic welding, to only incorporate strips in the stretched state, the person skilled in the art being able to readily select suitable patterns for this purpose, which are also further explained below.

If, for a selected connection pattern, the bound strips of the elastic film do not tear immediately when the laminate is formed by at least partially melting at the connection points, then surprisingly no great risk of tearing is to be expected even with later use. The specific properties of the laminate also play a role here because the lamination of the elastic strips in the stretched state and the subsequent draping of the nonwoven layers due to the elastic provision often do not stretch the elastic laminate over the length present in the lamination when used as intended becomes. When used as intended, the folds of the nonwoven layers formed by the elastic recovery are often pulled straight again, preferred materials for the nonwoven layers then producing a clearly perceptible stretch resistance. A user will then refrain from further stretching, so that the strips of the elastic film are protected against excessive stretching and then tearing, in particular at the connection points.

In the context of the invention, the strips of the elastic film each have a width between 3 mm and 15 mm. Basically, it is possible to match a pattern of connection points exactly to the position of the individual strips. Along the individual strips, it could be provided, for example, that connection points are provided only in the middle and not on the edge of the individual strips, in order to avoid undesired weakening, especially at the edge.

Such a repeatable alignment of a plurality of strips on a pattern of connection points is also encompassed by the present invention and extremely advantageous for certain applications, however, according to a preferred embodiment of the invention, the strips are precisely aligned on the one hand and the connection points on the other hand. A connection pattern is then selected which, on the one hand, ensures that all strips are securely integrated regardless of their exact position along the transverse direction and, on the other hand, prevents excessive weakening of the strips of the elastic film. In particular, the size and position of the connection points have to be matched to the width of the strips and the distance remaining between them.

At the edges of the strips and between the strips, the nonwoven layers are directly connected to one another by the connection points.

In contrast, different types of connection are possible in the area of the strips of the elastic film. At the discrete, adhesive-free connection points, which are preferably formed by ultrasonic welding, the nonwoven layers can be attached directly to the strips. The strips then remain as a layer between the two nonwoven layers.

Due to the energy input during ultrasonic welding, there is a local exposure to pressure and temperature. Precisely because the strips of the elastic film are under tensile stress along the stretch direction during lamination, the strips can also thin out or even form openings directly at the connection points. In such a case, it is then also possible for the nonwoven layers to be directly connected to one another through such an opening. In such a case, the connection of the nonwoven layers to the individual strips is not achieved by a material bond or an adhesion, but ultimately mechanically by a form fit. If the nonwoven layers are connected to one another by openings in the strips, these are also necessarily fixed there. Which type of connection is established can be influenced both by the procedure and the materials used, which is explained in more detail below. In addition, different patterns of connection points can also be expedient for the different types of connection.

Even if openings are formed during the ultrasonic welding, a type of bulge is then frequently observed at the openings, on which the melted material retracts and accumulates. Such a bead can at least partially compensate for the actual weakening through the opening.

Different types of connection can also be achieved by the configuration of the elastic film from which the strips are cut. For example, a multilayer elastic film can be provided, in which case not all film layers need to be elastic. Suitable embodiments are explained further below. In the context of such a configuration, it is also possible, for example, for the nonwoven layers to be connected only to outer layers of the elastic film.

The strips typically run at the same distance and with straight edges parallel to one another. Preferably the strips are immediate, i.e. H. connected to the nonwoven layers or arranged between them without further intermediate layers.

By integrating the strips of the elastic film in a stretched state, a clearly defined proof stress is specified. After the tensile forces cease to exist after the production of the laminate, the latter essentially resets itself until the strips of the elastic film have reached their initial length again in the force-free state. A certain permanent extension compared to the initial length can result from stiffening at the connection points. As will be explained further below, such an inherently undesirable stiffening can be limited to certain areas.

According to the corresponding pretensioning of the strips of the elastic film, the elastic laminate can be stretchable, for example, up to an elastic limit with an elongation between 30% and 300%, in particular between 50% and 250%. Within the scope of the invention, there is the advantage that the stability and tensile strength of the elastic laminate is largely determined by the nonwoven layers when the elastic limit is reached. Even if the strips themselves are particularly easy to stretch and thus the elastic laminate can be stretched to the elastic limit with little effort, the structure of the nonwoven layers which are not damaged by an activation which is frequently provided in accordance with the prior art can provide high strength. This means that, in contrast to an activated elastic laminate, particularly easily stretchable elastic films with a comparatively low tensile strength can be used.

In the relaxed state, the elastic film preferably has a thickness of only 30 μm to 80 μm, the width of the strips formed therefrom being between 3 mm and 15 mm, in particular between 5 mm and 12 mm. The stripes of the elastic film lie flat between the two nonwoven layers and are therefore not significantly bulky. Due to the flat arrangement of the strips, the elastic properties of the material can also be optimally used, with the area coverage between 20% and 80%, preferably between 50% and 75%, not only providing uniform elastic properties, but also an advantageous fold structure of the nonwoven layers between the elastic strips in the relaxed state.

The arrangement of the nonwoven layers in the relaxed state can also be referred to as a frill effect, which results in a particularly soft and pleasant surface, which is optimally gentle on a user even in direct skin contact.

In the context of the invention, the discrete adhesive-free connection points can be formed in different shapes and patterns. Various preferred configurations which are considered to be particularly expedient are explained below. Of course, however, the invention is not limited to these specific configurations, even if these are associated with specific advantages.

The connection points preferably have a rounded base area, to which a long side and a short side can be assigned. The base area can thus be oval and in particular elliptical, for example, the major axis then forming the long side and the minor axis forming the short side in the case of an ellipse. According to another preferred form, two semicircles are spaced apart and connected by a rectangular intermediate section. In the broadest sense, such a shape can be described as "pill-shaped" or "stadium-round". Finally, a rectangular basic shape with clearly rounded corners is also possible, for example. The ratio of the long side to the short side can be, for example, between 1.1: 1 and 3: 1, in particular between 1.3: 1 and 2: 1.

According to a development of the invention, it is provided that the long side described above is inclined with respect to the direction of expansion.

Whether an inclination of the long side is appropriate for a specific embodiment can also depend on the type of connection. If the elastic film is undamaged or only thinned at the connection points between the nonwoven layers, the oblique position can also cover a larger area along the transverse direction. If, on the other hand, openings occur in the elastic film at the connection points, it may be expedient to make the connection points as narrow as possible in the transverse direction so that the individual strips are only interrupted over a small proportion of their width. With such a type of connection, it can advantageously be provided that the long side is aligned along the direction of expansion.

When characterizing the elastic laminate, it should be noted that the dimensions and also the angular orientations change with regard to the relaxed state and the stretched state. In a stretched state, when the nonwoven layers are smooth and moreover unstretched, the structure is reached again during manufacture. The connection points are then available in a configuration, orientation and size, as was also provided during manufacture. For the characterization of the elastic laminate, reference can therefore be made to the stretched state described when the nonwoven layers are smooth and unstretched.

With regard to this stretched state, the long side can be inclined, for example, between 30 ° and 60 ° with respect to the stretching direction. In particular, it can be expedient if a first group of connection points starting from a central axis is inclined in a first direction and a second group of connection points opposite in a second direction by the specified value. In particular, the long side can be angled by +/- 45 ° in relation to the stretched state. As explained above, such an inclination can be expedient if the elastic film is retained at the connection points.

As already stated, the strips of the elastic film cover between 20% and 80%, in particular between 50% and 75% of the total area in the relaxed state. On the basis of the stripe width claimed and an equidistant arrangement, a typical spacing of adjacent stripes in the relaxed state is between 1 mm and 30 mm. It should be noted here that the area proportion of the elastic strips and the distance change only slightly during stretching because the strips essentially change in their thickness when stretched. Certain constrictions of the strips when stretching or widening in the case of elastic recovery are possible.

In the context of the invention, it should be noted that adhesive-free connection points and in particular ultrasonic welding points can contribute both to stiffening and to weakening.

Against this background, it is provided according to a preferred embodiment of the invention that in a stretched state, if - as described above - the nonwoven layers are smooth and unstretched, there are provided in strip-shaped stretching areas which are free of connection points, the ratio being one the width of the expansion regions determined along the direction of expansion to the length of the connection points determined along the direction of expansion lies between 0.5 and 6, in particular between 2 and 5.

Even if the expansion areas run in the transverse direction, they do not have to be aligned exactly parallel to the expansion direction. From a manufacturing point of view in particular, it can be expedient if the expansion areas run with a slight inclination in the transverse direction. If the individual expansion areas not having any connection points are aligned exactly along the transverse direction, there would be no support between the anvil roll and sonotrode in the case of ultrasound welding with an anvil roll and a sonotrode, or there would be an increased distance between the sonotrode and the back areas of the anvil roll between the projections provided for the formation of the connection points. If, on the other hand, the expansion areas run somewhat obliquely with respect to the transverse direction, as described, a practically continuous support between the anvil roller and the sonotrode can be achieved. This can reduce the risk of damage and wear to the system.

The degree of inclination also depends on the width of the laminate. The inclination is usually chosen such that the anvil roller is supported practically continuously by at least one projection relative to the sonotrode. With the usual widths of the laminate, the inclination can be, for example, between 1 ° and 20 °, in particular between 2 ° and 10 °.

With regard to the stretching of the material along the stretching direction, the stretching areas are not affected by stiffening or weakening by the omission of connection points at the stretching areas. Surprisingly, it can also be accepted that the nonwoven layers and the strips of the elastic film are not directly connected to one another over the corresponding length.

On the other hand, it is preferably provided for some of the embodiments that the connection points cover at least 80%, preferably completely, of the transverse direction in a projection. This means that along the longitudinal direction there are no major linear sections at which there are no connection points at all along the direction of expansion. If, on the other hand, larger free spaces extending in the direction of expansion would remain, the secure integration of the strips of the elastic film could not be ensured if, according to a preferred embodiment of the invention, no exact repeat or exact alignment of the strips to the pattern of the connection points is provided. With regard to the projection described, the transverse direction can also be completely covered by connection points. It is then not possible to find a straight line which runs along the direction of expansion and does not intersect individual connection points. In view of the projection described, the connection points can of course also be provided with a certain overlap in order to completely cover the transverse direction. The at least extensive coverage of the transverse direction described can also advantageously be achieved in that successive connecting points have an offset along the transverse direction. The covering described in the transverse direction is provided in particular if the elastic film is retained at the connection points and does not form any openings there.

According to a preferred embodiment it is provided that the connection points are arranged in rows which run exactly parallel to the transverse direction or preferably with a certain inclination in the transverse direction. As already indicated above, an offset to one another can then also be provided in the case of rows which follow one another directly along the stretching direction. For example, successive rows can be arranged in a gap, so that exactly every second row again has the same orientation with respect to the transverse direction.

According to a further aspect of the invention, the rows following one another in the direction of expansion can also have different distances. In particular, it can be provided that the rows have a first spacing and a larger second spacing in a recurring sequence along the stretching direction. For example, in the case of pairs of two rows or groups of at least three rows, the small first distance can be provided between the rows of the pair or group. If the rows are then offset transversely, there may be some overlap with respect to the individual pairs or groups even along the direction of stretch. The locally closer arrangement of the connection points results in a particularly reliable connection of the laminate, with a certain impairment of the elasticity and elasticity being accepted due to the usual stiffening of the material by the connection points. The larger second distance is then provided between the pairs or groups, in particular in order to form the previously described expansion ranges. In a simple embodiment, a first distance and a second distance can always alternate along the direction of expansion.

The individual connection points typically have an area between 0.2 mm ² and 5 mm ² , in particular between 0.3 mm ² and 2 mm ² .

It is preferably provided that the connection points in the stretched state, when the nonwoven layers are smooth and unstretched, cover between 3% and 40%, in particular between 25% and 50% of the total area.

1. a) Extrudieren einer elastischen Folie;
2. b) Zerschneiden der elastischen Folie zur Bildung von Streifen;
3. c) Einbringen der Streifen in einem gedehnten Zustand mit einer Dehnung zwischen 30 % und 300 % sowie mit einem Abstand zueinander zwischen zwei Nonwoven-Lagen;
4. d) Erzeugen von diskreten klebstofffreien Verbindungsstellen durch Ultraschallschweißen;
5. e) Entspannen des aus den Nonwoven-Lagen und den Streifen gebildeten Laminates.

The invention also relates to a method for producing the elastic laminate described above, comprising the steps:

1. a) extruding an elastic film;
2. b) cutting the elastic film to form strips;
3. c) inserting the strips in a stretched state with an elongation between 30% and 300% and with a distance from one another between two nonwoven layers;
4. d) creating discrete adhesive-free junctions by ultrasonic welding;
5. e) relaxing the laminate formed from the nonwoven layers and the strips.

The production direction in which the elastic film is extruded as a monofilm or preferably co-extruded as a multilayer film is also referred to as the machine direction. The film is preferably cut into strips in such a way that the individual strips also run along the machine direction, which is advantageous solely in terms of the procedure because the strips can then also be formed as an endless material and easily processed further.

Especially when the film is stretched for the first time, a significantly greater force is required for a stretch than with subsequent stretches. This is especially true if how Still described in detail below, the elastic film is provided with thin non-elastic cover layers, so that the elastic film itself must first be activated to a certain extent in order to provide easy stretchability. Against this background, it is provided according to a preferred embodiment of the method that either the extruded film or the strips cut therefrom are first pre-stretched between the nonwoven layers before being introduced. In particular, this first pre-stretch is preferably stronger than the pretension with which the elastic strips are laminated with the nonwoven layers in the stretched state. The stronger pre-stretching ensures that a particularly slight stretching of the elastic film or the strips formed therefrom is possible at least up to the yield point specified by the method.

For example, it can be provided that the extruded elastic film or the strips cut from it are pre-stretched by 300% to 500% between the nonwoven layers before insertion, the length resulting after tension having a permanent deformation (permanent set) as The starting length for the subsequent stretching during lamination is to be taken as a basis.

According to a preferred embodiment of the invention, it is provided that the elastic film has a multilayer structure with an elastic core layer and at least one outer layer, even if a configuration as a monofilm is also possible. It should be noted that typical elastic materials such as styrene block copolymers or even elastic thermoplastic olefins often have considerable stickiness, so that monofilms formed with them cannot be easily wound up and unwound for transport, storage and processing.

In addition to increased tensile forces due to the stickiness described, there is even the risk of blocking, so that a corresponding role can then no longer be used. A further disadvantage of a monofilm is that it already stretches its transport very much during handling due to the necessary tensile forces. If, on the other hand, a multilayer structure with at least one non-elastic, usually thin cover layer is used, such a film can be handled very well and without substantial stretching, at least with moderate tensile forces during production.

In addition to a two-layer configuration with a core layer and an outer layer, a three-layer structure and in particular a symmetrical three-layer structure with a core layer between two outer layers are particularly preferred.

Typical materials for the core layer are styrene block copolymers, such as SIS, SBS and SEBS (see for example “Saechtling Kunststoff Taschenbuch”, 31st edition, 2013, Carl Hanser Verlag) or thermoplastic elastomers based on polyolefin copolymers in practice also referred to as TPE-O.

The cover layers, on the other hand, are preferably formed from conventional non-elastic polyolefins, such as polyethylene, polypropylene and their copolymers, various types of seal being suitable for this purpose. LDPE and LLDPE are suitable, for example, although these can be mixed with further constituents, such as, for example, PP / PE copolymer or typical additives and additives, such as, for example, talc.

Furthermore, other additives such as antiblocking agents, color pigments or the like can also be provided.

For the films described, it is generally sufficient and expedient if the outer layers are made very thin. The outer layers can, for example, each have a thickness between 1 μm and 10 μm, in particular between 2 μm and 5 μm. The core layer responsible for the elastic properties, on the other hand, is thicker and, depending on the choice of material, typically has a thickness between 15 μm and 60 μm, in particular between 20 μm and 50 μm.

The thickness ratio of the core layer to one of the outer layers is typically in a range between 5: 1 and 12: 1.

As described above, different types of connection at the connection points are possible within the scope of the invention in order to bind the strips of the elastic film into the laminate. The nonwoven layers can be connected to one another on the strips with the elastic film or through openings in the elastic film. In addition, different intermediate stages or locally different connections are possible with a laminate.
A connection of the nonwoven layers with the elastic film without the formation of openings, pores or severe material constrictions can be achieved, for example, in that in the case of a multilayer, in particular at least three-layer elastic film, the core layer or an inner layer has a higher layer compared to the outer layers Has melting point and / or a higher viscosity, so that the Core layer or the inner layer is retained even with ultrasonic welding or a comparable energy effect.

Additionally or alternatively, the materials of the elastic film or, in the case of a multilayer structure, at least the outer layers of the elastic film on the one hand and the nonwoven layers on the other hand can be matched to one another in such a way that a material connection is favored by fusing.

In this context, the fibers of the nonwoven can also be specially adapted or selected. For example, the nonwoven can be formed from bicomponent fibers or at least have bicomponent fibers which have a low-melting component, in particular as a sheath in a core-sheath structure. The high-melting component, in particular the core, then preferably remains in its structure, while the low-melting component enables a reliable material connection. Similar advantages can also be achieved if a mixture of high-melting and low-melting fibers is present in the nonwoven.

According to the invention, the outside of the laminate is formed from nonwoven layers. Various currently common types of nonwoven are considered, such as spunbond nonwoven, carded nonwoven and meltblown nonwoven. A multilayer structure which combines the various nonwoven types with one another is particularly preferably used. With such a multilayer structure, very good properties with regard to strength and feel can be achieved even with a low basis weight. For example, a nonwoven with a layer structure SMS, SSMMS or the like can be provided. As described above, the individual layers can also have a fiber mixture and / or bicomponent fibers.

The weight per unit area of the nonwoven is typically between 10 g / cm ² and 35 g / cm ² , in particular between 13 g / m ² and 25 g / cm ² .

• 1 ein elastisches Laminat für Windelverschlüsse in einem entstandenen Zustand,
• 2 das elastische Laminat gemäß der 1 in einem vollständig gedehnten Zustand an einer Dehngrenze,
• 3 ein Muster von diskreten klebstofffreien Verbindungsstellen des Laminates in dem gedehnten Zustand gemäß der 2 bzw. bei der Herstellung,
• 4A die Herstellung des elastischen Laminates in einer schematischen Darstellung,
• 4B einen Verfahrensschritt zur Bildung von beabstandeten Folienstreifen,
• 5 die schematische Darstellung einer Einweg-Windel,
• 6a bis c alternative Ausgestaltungen zu dem Muster gemäß 3,
• 7 eine schematische Darstellung eines Ultraschallverschweißens in einer Draufsicht,
• 8a, b weitere alternative Ausgestaltungen zu dem Muster gemäß 3.

The invention is explained below on the basis of a drawing which represents only one exemplary embodiment. Show it:

• 1 an elastic laminate for diaper closures in the resulting state,
• 2nd the elastic laminate according to the 1 in a fully stretched state at a yield point,
• 3rd a pattern of discrete adhesive free joints of the laminate in the stretched state according to the 2nd or in the manufacture,
• 4A the production of the elastic laminate in a schematic representation,
• 4B a method step for the formation of spaced film strips,
• 5 the schematic representation of a disposable diaper,
• 6a to c alternative configurations to the pattern according to 3rd ,
• 7 1 shows a schematic representation of an ultrasound welding in a top view,
• 8a, b further alternative configurations to the pattern according to 3rd .

The 1 shows a plan view of an elastic laminate, which is particularly intended for diaper closures. As can be seen in a comparative analysis with the 4a the elastic laminate comprises two nonwoven layers 1 , which also form the outside of the elastic laminate. Stripes run along an elongation direction D. 2nd an elastic film.

The strips are according to the invention 2nd under tension between the nonwoven layers 1 involved, with the nonwoven layers 1 in one in the 1 shown relaxed state by the restoring forces of the strips integrated under pretension 2nd wrinkled along the stretching direction D, ie along the strips 2nd are gathered. The nonwoven locations 1 are through discreet adhesive-free connection points 3rd with the stripes 2nd and joined together between the strips. The connection points are for the sake of clarity 3rd in the 1 and 2nd not shown. For this purpose, the 3rd referenced in the section of the pattern of the connection points 3rd is reproduced, with two strips as an example 2nd are dashed.

The representation of the 3rd refers to a stretched state of the laminate according to the 2nd or on the configuration of the laminate during manufacture, in which the film strips 2nd are stretched along the stretching direction D.

The strips of the elastic film typically cover between 20% and 80%, in particular between 50% and 75% of the total area in the relaxed state, this value generally not changing significantly as a result of the stretching because the strips have thinned out 2nd the elastic film usually takes place mainly in the direction of the thickness. The thickness of the strips 2nd is usually between 30 µm and 80 µm in the relaxed state.

As from the 3rd can be seen, the connection points 3rd each have a rounded base with a long side a and a short side b. The connection points 3rd can for example be oval and in particular elliptical. The embodiment of the 3rd shows, however, an embodiment in which the connection points are each formed by semicircles, which are connected by a rectangular intermediate section.

The ratio of the long side a to the short side b can be, for example, between 1.1: 1 and 3: 1, in particular between 1.3: 1 and 2: 1.

From the 3rd it can also be seen that the connection points 3rd in along a transverse direction Q extending rows are arranged, the along the direction of stretch D immediately successive rows are offset from one another. It can also be seen that the connection points 3rd are inclined alternately to the left and right with respect to the elongation direction D with their long sides a.

Due to the inclination, the long side corresponds to a and the short side b not length d ₂ by the individual liaison offices 3rd along the direction of stretch and the width determined along the transverse direction q ₂ covered width. From the 3rd it can be seen that in the stretched state when the nonwoven layers 1 are smooth and unstretched (according to the structure during manufacture) along the transverse direction Q extending strip-shaped stretch areas 4th are provided at which there are no connection points 3rd are located. The ratio of the along the stretch direction D certain width of the expansion ranges d ₁ to that along the stretch direction D certain length d ₂ the connection points are typically between 0.5 and 6, in particular between 2 and 5.

It can also be seen that the connection points 3rd the transverse direction in a projection Q cover at least 80%. With regard to the 3rd such a projection is to be formed, for example, on a horizontal baseline. So while along the cross direction Q extending strip-shaped expansion areas, there are only very narrow linear areas along the direction of expansion between the connection points 3rd . Especially when the connection points 3rd are slightly larger, the transverse direction Q be completely covered in the projection. As a result, regardless of the exact orientation of each strip 2nd always sufficient integration through the connection points 3rd is guaranteed.

From the 3rd it can also be seen that for the arrangement of the individual strips 2nd towards the connection points 3rd no exact repeat is provided. In practice, it is expected that each streak 2nd versus the pattern of junctions 3rd is arranged somewhat differently. The pattern of connection points 3rd However, it should be chosen so that it does not depend on a particular orientation and that an adequate connection and strength is always ensured.

The ratio of the width determined along the transverse direction q ₁ of elastic strips 2nd to the along the direction Q certain width q ₂ the connection points are typically between 2: 1 and 9: 1.

The individual connection points 3rd can have, for example, an area between 0.2 mm ² and 5 mm ² , in particular between 0.3 mm ² and 2 mm ² .

With regard to the stretched state, the joints can 3rd for example cover an area between 3% and 40%, in particular between 5% and 25% of the total area.

The 4A shows an example of individual steps for producing the elastic laminate. Accordingly, a previously extruded elastic film is fed and with knives 5 in stripes 2nd cut. The cut strips 2nd are fanned out equidistantly, which results from the schematic representation of the 4A does not emerge. For example, according to the 4B the Stripes 2nd around an inclined roller 6 be performed.

The Stripes 2nd are then at a distance from each other between two nonwoven layers 1 brought in.

In the 4A It is also shown that the elastic film used to form the strips 2nd at a first speed v ₁ is fed while the two nonwoven layers 1 and also subsequently the laminate formed at a higher speed v ₂ be transported. From the speed difference of v ₁ and v ₂ the degree of stretching of the individual strips results 2nd in connection.

The actual formation of the laminate takes place by producing the connection points described above in detail on an anvil roller 7 and a cooperating sonotrode 8th .

The 5 shows a preferred application of the elastic laminate according to the 1 and 2nd . The 5 shows a disposable diaper with a diaper body 9 who between a liquid-tight outer layer and a liquid-permeable inner layer a liquid-absorbing core 10th has two sections 11 of the previously described elastic laminate on the diaper body 9 connected and as side connections between a front part and a rear part of the diaper body 9 are provided. The sections are specific 11 each in a first end on the diaper body 9 connected and carry a closure element at a second end 12th , for example a hook material. The closure elements 12th are intended to be attached to a front section of the diaper base body when the disposable diaper is put on, for which purpose there is then provided a support area also referred to as a landing zone.

The elastic laminate is characterized by a low use of materials, low manufacturing costs and still good functional properties. The elastic laminate is therefore also very suitable for other disposable items. With the elastic laminate, for example, waist bands of an incontinence product or a disposable heating belt can also be formed.

That in the 3rd shown patterns of discrete adhesive-free joints 3rd is particularly useful if in the area of the strips 2nd at the connection points there 3rd the elastic film does not form any openings, so the nonwoven layers 1 are attached to the elastic film.

If, on the other hand, the energy input from the ultrasound welding on the strips 2nd the elastic film leads to a hole formation and then the nonwoven layers 1 in the area of the strips connected to one another through the holes formed, other patterns may be expedient, which are the strips 2nd weaken less.

So they show 6a to 6c an alternative pattern of junctions 3rd , which is particularly useful in such a case. The 6a and 6c differ by a different width of the strip 2nd , the distance between adjacent strips being exemplary 2nd exactly the width of the strip 2nd corresponds. The Stripes 2nd then cover (at least based on the stretched state during manufacture) 50% of the total area. Of course, this surface coverage is only an example, the distance between adjacent strips 2nd within the scope of the invention can be larger and smaller than the width of the strips 2nd .

To the stripes 2nd The non-round connection points are not too weak to weaken along their width 3rd with its long side a along the direction of stretch D aligned so that then the strips 2nd at the individual connection points 3rd are weakened only over the length of the short side b.

As with the pattern according to the 3rd the connection points are arranged in rows which are offset from one another.

According to the 6a to 6c show the rows along the stretch direction D but alternately a first distance and a larger second distance. The rows in succession with the first small spacing form a kind of double row 13 , which enables a particularly reliable connection. Due to the larger second distance, the strip-like stretch areas 4th provided which is in the transverse direction Q run.

Looking closely at the 6a to 6c it can be seen that the rows and thus also the expansion areas D opposite the transverse direction Q are slightly inclined, which offers particular advantages in terms of production technology.

The 7 the area of the sonotrode is highly schematized in a plan view 8th (compare 4a) , with the double rows on the laminate 13 are indicated in their oblique position. The inclination is according to the 7 adjusted to the width of the laminate so that between the anvil roller 7 and the sonotrode 8th always support by at least one projection of the anvil roller provided for the formation of the connection points 7 he follows. Such an inclination is also in the pattern according to the 3rd expedient, even if it is not shown there.

According to the 6a corresponds to the distance between two adjacent connecting points in a row 3rd , each related to the center of the connection point 3rd , exactly the width and spacing of the stripes 2nd . As a result, all stripes 2nd are fixed in the same way.

As a rule, however, the individual strips 2nd not exactly in relation to the pattern from connection points 3rd can or should be aligned, the design according to 6a be disadvantageous in practice. If for a strip 2nd If the (not precisely specified) alignment is disadvantageous with regard to the mechanical properties, then this applies to all strips 2nd .

According to the 6b and 6c it is therefore intended that the strips 2nd and the distance between the strips 2nd either slightly larger ( 6b) or a little smaller ( 6c ) as the distance (center to center) of adjacent connection points 3rd is. The distance between adjacent connection points 3rd can for example 5% to 20% larger than the width of the strips 2nd .

In the 8a and 8b is shown as an example that the connection points 3rd can also be made circular, with rows of connection points then also 3rd along the direction of expansion D, for example, equidistant ( 8a) or in double rows 13 ( 8b) can be arranged.

A carded nonwoven with a weight per unit area of 22 g / m ^{2 is} provided according to a concrete test sample. A carded nonwoven, for example, which is sold under the name "ThermoStrain" by Mondi Ascania GmbH, is suitable. The Stripes 2nd are formed from an elastic film based on SBS, which can be stretched by 250% along a machine direction MD which coincides with the stretching direction D. The stripe width in the unstretched state is 3 mm in the concrete sample.

The film has a symmetrical structure with an elastic core layer. The core layer has a thickness of 42 μm, SBS being mixed with polystyrene (PS) and oil and titanium dioxide (TiO ₂ ) additionally being present as a white batch. The symmetrical outer layers each have a thickness of only 4 µm, with a blend of polyethylene (PE) and polypropylene (PP) additionally containing talc.

As already explained at the beginning, the elastic properties of the laminate come from the strips 2nd the elastic film determined. It goes without saying that the elastic properties also vary significantly due to the strip width and the strip spacing and thus ultimately the degree of coverage by the strips and can be adapted to the respective requirements.

QUOTES INCLUDE IN THE DESCRIPTION

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Patent literature cited

• EP 3228292 A1 [0006, 0009]

Claims (21)

Elastic laminate with two non-woven layers (1) forming opposing outer sides and with strips (2) of an elastic film running between the non-woven layers (1) and running in a stretching direction (D), the strips (2) being pretensioned between the Nonwoven layers (1) are bound in and the nonwoven layers (1) are folded in a relaxed state by the restoring forces of the strips (2) bound under pretension along the stretching direction (D) and the strips are transverse to the stretching direction ( D) are arranged at a distance from one another along a transverse direction (Q) and the width (q ₁ ) of the strips (2), determined perpendicular to the direction of expansion (D) along the transverse direction (Q), is between 3 mm and 15 mm, thereby characterized in that the nonwoven layers (1) are connected to one another and / or to the strips (2) of the elastic film at discrete adhesive-free connection points (3). Elastic laminate after Claim 1 , characterized in that the connection points (3) are designed as ultrasonic welding points. Elastic laminate after Claim 1 or 2nd , characterized in that in the relaxed state the thickness of the strips (2) is between 30 µm and 80 µm. Elastic laminate according to one of the Claims 1 to 3rd , characterized in that the strips (2) of the elastic film cover between 20% and 80%, in particular between 50% and 75% of the total area in the relaxed state. Elastic laminate according to one of the Claims 1 to 4th , characterized in that the connection points (3) each have a rounded base with a long side (a) and a short side (b). Elastic laminate after Claim 5 , characterized in that the long sides (a) are inclined relative to the direction of expansion (D). Elastic laminate according to one of the Claims 1 to 6 , characterized in that the distance of adjacent strips determined in the relaxed state along the transverse direction (Q) is between 1 mm and 30 mm. Elastic laminate according to one of the Claims 1 to 7 , characterized in that in a stretched state, when the nonwoven layers (1) are smooth and unstretched, strip-shaped stretching areas (4) are provided which run in the transverse direction (Q) and are free of connection points (3), the ratio being one the width (d ₁ ) of the expansion regions, determined along the direction of expansion (D), lies between 0.5 and 6, in particular between 2 and 5, to the length (d ₂ ) of the connection points (3) determined along the expansion direction (D). Elastic laminate according to one of the Claims 1 to 8th , characterized in that the connection points (3) in a projection cover the transverse direction (Q) to at least 80%, preferably completely. Elastic laminate according to one of the Claims 1 to 9 , characterized in that the connection points (3) are arranged in rows which run in the transverse direction (Q). Elastic laminate after Claim 10 , characterized in that the rows immediately following one another along the direction of expansion (D) are offset from one another. Elastic laminate after Claim 10 or 11 , characterized in that the rows along the direction of expansion (D) have a first distance and a larger second distance in a recurring sequence. Elastic laminate according to one of the Claims 1 to 12th , characterized in that the ratio of the width (q ₁ ) of the elastic strips (2) determined along the transverse direction (Q) to the width (q ₂ ) of the connecting points (3) determined along the transverse direction (Q) between 2: 1 and 9: 1, in particular between 3: 1 and 6: 1. Elastic laminate according to one of the Claims 1 to 13 , characterized in that the connection points (3) each have an area between 0.2 mm ² and 5 mm ² , in particular between 0.3 mm ² and 2 mm ² . Elastic laminate according to one of the Claims 1 to 14 , characterized in that the connection points (3) cover between 3% and 40%, in particular between 5% and 25% of the total area in the stretched state. Elastic laminate according to one of the Claims 1 to 15 , characterized in that the elastic film has a multi-layer structure, in particular an at least three-layer structure with a core layer between two cover layers. Process for producing an elastic laminate according to one of the Claims 1 to 16 comprising the steps of: a) extruding an elastic film; b) cutting the elastic film to form strips (2); c) introducing the strips (2) in a stretched state with an elongation between 30% and 300% and with a spacing between two nonwoven layers (1); d) generation of discrete adhesive-free connection points (3) by ultrasonic welding; e) relaxing the laminate formed from the nonwoven layers (1) and the strips (2). Procedure according to Claim 17 , wherein the elastic film is extruded in a machine direction (MD) and wherein the elastic film is cut into the strips (2) along the machine direction (MD). Procedure according to Claim 17 or 18th , wherein the extruded elastic film or the strips (2) cut therefrom are or are pre-stretched between the nonwoven layers (2). Disposable diaper with a diaper body (9), which has a liquid-absorbing core (10) between a liquid-tight outer layer and a liquid-permeable inner layer, two sections (11) of an elastic laminate according to one of the Claims 1 to 16 connected to the diaper body (9) and provided as a lateral connection between a front part and a rear part of the diaper body (9). Disposable diaper after Claim 20 The sections (11) are each connected to the diaper base (9) at a first end and carry a closure element (12) at a second end.

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