WO2012036599A1

WO2012036599A1 - Elastic laminate material and an absorbent article containing the elastic laminate

Info

Publication number: WO2012036599A1
Application number: PCT/SE2010/050986
Authority: WO
Inventors: Per Floberg
Original assignee: Sca Hygiene Products Ab; Kinderdal, Mats
Priority date: 2010-09-14
Filing date: 2010-09-14
Publication date: 2012-03-22

Abstract

An elastic laminate material (20) comprising at least one elastic film layer and at least one nonwoven layer, said elastic film layer and said nonwoven layer being bonded together in a bonding pattern comprising a plurality of bonding elements (10,11 ), in which said elastic film and said nonwoven are fused together, wherein the elastic film is in a stretched condition in a machine direction (MD) during bonding. The bonding pattern comprises at least two different types of bonding elements, wherein a first type of bonding elements (10) have a perimeter (p1 ), said perimeter having a length (a1) of at least 1.25 mm extending in a direction forming an angle of between 80 and 100° to said machine direction (MD), and a second type of bonding elements (11) having a perimeter (p2), said perimeter having a length (a2) of not more than 1 mm extending in said direction. Apertures (12) are formed in the elastic film in close vicinity of at least some of the first type of bonding elements (10), said apertures being caused by rupture of the elastic film as a result by stretching. The invention further refers to an absorbent article containing the elastic laminate.

Description

ELASTIC LAMINATE MATERIAL AND AN ABSORBENT ARTICLE CONTAINING THE ELASTIC LAMINATE

TECHNICAL FIELD

The present invention refers to an elastic laminate material comprising at least one elastic film layer and at least one nonwoven layer, wherein the elastic film layer and the nonwoven layer are bonded together in a bonding pattern comprising a plurality of bonding elements, in which said elastic film and said nonwoven are fused together. The invention further refers to an absorbent article containing the elastic laminate.

BACKGROUND OF THE INVENTION

Elastic laminate materials are commonly incorporated in absorbent articles, especially pant-like absorbent articles such as pant diapers, sanitary pants, incontinence pants, and the like. Such articles comprise an absorbent unit arranged in a pant-shaped chassis and are worn in the manner of a pair of underpants. Elastic laminate materials may be incorporated as part of front and/or rear body panels and/or as elastic side panels in a pant-like absorbent article.

If the elastic film is in a stretched condition in a machine direction (MD) during bonding to the at least one nonwoven layer, the nonwoven layer can gather between the bonding sites in a relaxed condition and thus make the laminate material elastically stretchable in said machine direction. Such bonding by melt fusing may result in that apertures are formed in the film in the bond sites or adjacent thereto. This will make the elastic film and the laminate breathable, which is an advantage and increases wearer comfort in an absorbent article.

WO 2008/026106 discloses a breathable elastic laminate suitable to be incorporated in an absorbent article. The laminate comprises an elastic film and a nonwoven web bonded together by melt fusing in a plurality of bonding sites while the film is in a stretched condition. Apertures are formed in the film in the bonding sites concurrently with melt fusing without substantially softening the polymer material of the nonwoven web. US 2007/0048497 discloses an elastic laminate comprising an elastic film and a necked nonwoven thermally bonded to the elastic film. The elastic film comprises a core layer and a skin layer. The bond sites are shaped as intermittent lines extending in the cross direction of the elastic laminate. Stretch thinning of the skin layer of the film results in the formation of apertures in the skin layer adjacent the bond sites.

There is still a need for elastic laminate materials that provide breathability and comfort especially when incorporated as a component in an absorbent article. It is an object of the present invention to provide such a breathable elastic laminate provided by stretch- bonding of an elastic film to a nonwoven layer, wherein the formation of apertures in the film is controlled and the risk for undesired rupture of the film is reduced or avoided.

SUMMARY OF THE INVENTION

The invention refers to an elastic laminate material comprising at least one elastic film layer and at least one nonwoven layer, said elastic film layer and said nonwoven layer being bonded together in a bonding pattern comprising a plurality of bonding elements, in which said elastic film and said nonwoven are fused together, said elastic film being in a stretched condition during bonding in a machine direction (MD). The bonding pattern comprises at least two different types of bonding elements, wherein a first type of bonding elements have a perimeter, said perimeter having a part forming an angle of between 80 and 100° to the MD direction, said part having a length of at least 1.25 mm as measured perpendicular to the MD direction in the form of an imaginary connection line

interconnecting the end points of such a part of the perimeter forming an angle of between 80 and 100° to the MD direction, and a second type of bonding elements having a perimeter, said perimeter having a part forming an angle of between 80 and 100° to the MD direction, said part having a length of not more than 1 mm as measured perpendicular to the MD direction in the form of an imaginary connection line interconnecting the end points of such a part of the perimeter forming an angle of between 80 and 100° to the MD direction, and wherein apertures being formed in the elastic film in close vicinity of at least some of the first type of bonding elements, said apertures being caused by rupture of the elastic film as a result by stretching and extend from said part of perimeter of the respective bonding element forming an angle of between 80 and 100° to the MD direction, and are located outside the area of the respective bonding element. Said first type of bonding elements may have an elongated shape with a length/width- relationship of at least 2: 1 .

Said second type of bonding elements may have a length/width relationship of not more than 1.5: 1 , preferably 1 : 1.

The length of the first type of bonding elements may be is at least 30% larger than the length of the second type of bonding elements. The length of the first type of bonding elements may be not more than 7 mm, preferably not more than 4 mm.

The length of the second type of bonding elements may be not more than 3 mm. Said part of the perimeter of the first type of bonding elements forming an angle of between 80 and 100° to the MD direction may have a length of between 1 .5 and 2 mm as measured perpendicular to the MD direction in the form of an imaginary connection line interconnecting the end points of such a part of the perimeter forming an angle of between 80 and 100° to the MD direction.

Said length of the perimeter of said second type of bonding elements extending in a direction forming an angle of between 80 and 100° to said machine direction may be a continuous length of not more than 1 mm, preferably not more than 0.5 mm. At least one second bonding elements may be located at a distance of between 1 and 7mm from said perimeter of a respective first bonding element having a length of at least 1 .25 mm, said distance being measured in the machine direction of the laminate and between the respective perimeters of the first and second bonding elements. The total number of the second type of bonding elements is at least 10% larger than the total number of the first type of bonding elements.

The total number of the second type of bonding elements is at least 50% and preferably at least 100% larger than the total number of the first type of bonding elements. The laminate may comprise at least two nonwoven layers, wherein the elastic film is located between the nonwoven layers.

Said bonding pattern may comprise bonding areas spaced apart, each bonding area comprising a plurality of first and second type of bonding elements and having a periphery, said bonding areas are separated from adjacent bonding areas by unbonded areas, wherein only second type of bonding elements are located along the periphery of each bonding area. Said unbonded areas may form bands, each band extending in at least one main direction and wherein at least a main part of the bonding areas each is adjacent to at least two bands of unbonded areas, said at least two bands extending in at least two different main directions. The invention further refers to an absorbent article comprising an inner bodyside liner and an absorbent core located between the outer cover and the inner bodyside liner, wherein the absorbent article includes an elastic laminate as described above.

The absorbent article may be a pant-type article comprising front and back body panels, wherein at least a part of said front and/or back body panels comprises said elastic laminate as a sole component. The elastic laminate may extend the entire width, as seen in the transverse direction, of at least one of the front and back body panels.

The absorbent article may be a pant-type article comprising elastic side panels, wherein at least a part of said elastic side panels comprises said elastic laminate as a sole component.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will below be described with reference to some embodiments shown in the accompanying drawings.

Fig. 1 is a top view of one embodiment of a bonding pattern for a bonded elastic laminate according to the invention illustrating the two types of bonding elements.

Fig. 2 a-g illustrates some embodiments of the first type of bonding elements.

Fig. 3 a and b illustrate a pair of embodiments of the second type of bonding elements. Fig. 4 illustrates the angle referred to that is formed between the perimeter of the bonding elements and the machine direction of the elastic laminate.

Fig. 5 is a photo on an enlarged scale of a bonded laminate according to the invention. Fig. 6 is a top view of one embodiment of a bonding pattern for an elastic laminate according to the invention showing a larger part of the bonding pattern comprising the first and second type of bonding elements.

Fig. 7 is a top view of a second embodiment of a bonding pattern.

Fig. 8 is a view of a pant-type absorbent article.

Fig. 9 is a further view of a pant-type absorbent article having elastic side panels.

Fig. 10 is a photo of an elastic laminate illustrating measurement of the bonded area of the elastic laminate.

Fig. 1 1 is a graph showing force vs. elongation for an elastic laminate.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

An elastic laminate material 20 according to the invention comprises at least one elastic film layer and at least one fibrous nonwoven layer. In one embodiment the elastic laminate comprises two nonwoven layers having an elastic film layer there between. Suitable nonwoven materials and elastic films are selected depending on the intended use of the elastic laminate. For use in an absorbent article suitable materials are given below.

The layers are bonded together in a bonding pattern comprising a plurality of bonding elements 10, 1 1 , in which said elastic film and said nonwoven are fused together. The bonding technique can be thermal point bonding, ultrasonic bonding or the like. Thermal point bonding employs a nip formed between two rolls, at least one being patterned. One or both rolls are heated. Ultrasonic bonding employs a nip formed between an ultrasonic horn and a patterned roll. In both techniques, which per se are well-known in the art, the patterned roll comprises a plurality of raised bonding elements to bond the film to the nonwoven layer(s) in a bonding pattern formed by the raised bonding elements.

The elastic film is in a stretched condition during bonding, said stretching is in a machine direction (MD) of the laminate. The term "machine direction" (MD) generally refers to the direction in which the laminate is produced. The term "cross-machine direction" (CD) generally refers to a direction perpendicular to the machine direction. The degree of stretching should be at least 100%, preferably in the range 300 to 500%. After relaxation of the film the nonwoven layer(s) can gather between the bonding sites and thus make the laminate material elastically stretchable in said machine direction. The bonding pattern comprises at least two different types of bonding elements, a first type of bonding elements 10 and a second type of bonding elements 1 1 .

The first type of bonding elements 10a has a length L1 defined as the largest extension in the CD or at an angle ±10° to the CD, when applicable. The width W1 of the first type of bonding elements 10a is defined as the largest dimension in a direction perpendicular to the length direction L1 . The first type of bonding elements preferably has an elongated shape with a length/width-relationship L1/W1 of at least 2:1 .

The length L1 of the first type of bonding elements 10a is preferably not more than 7 mm, preferably not more than 4 mm.

The first type of bonding elements 10 has a perimeter p1 , and the second type of bonding elements 1 1 has a perimeter p2. Part of the perimeter p1 of the first type of bonding elements 10a forms an angle of between 80 and 100° to the MD direction. If one interconnects the end points of such a part of the perimeter p1 forming an angle of between 80 and 100° to the MD direction, by a connection line a1 extending perpendicular to the MD direction, said connection line a1 should have a length of at least 1.25 mm. Preferably it should have a length between 1 .5 and 2 mm. The angle of a curved surface is measured as the tangent to the surface.

The part of the perimeter forming an angle of between 80 and 100° to the MD direction is either continuous, or exhibits discontinuities. In the case of a bonding element having a "micro-prickled" or "micro-rough" the "perimeter" may be considered as an imaginary line which is a tangent to the tips of the "micro-prickles" or "micro-roughness". This is illustrated in Fig. 2f. The perimeter may also have a "stepped" configuration comprising a plurality of parts forming an angle of between 80 and 100° to the MD direction and which are interrupted by parts of the perimeter forming a different angle to the MD direction. This is illustrated in Fig. 2g. The length al is then measured as the sum of the lengths of said parts forming an angle of between 80 and 100° to the MD direction, provided that they are located along the same side of the bonding element 10a with respect to a longitudinal centreline of the respective bonding element. Each bonding element 10a may have parts of the perimeter p1 forming an angle of between 80 and 100° to the MD direction on both sides of the longitudinal centreline. The length a1 is however only measured on one of the sides of the respective bonding element 10a.

The first type of bonding elements 10 has a length L1 defined as the largest extension in the CD or at an angle ±10° to the CD, when applicable. The width W1 of the first type of bonding elements 10 is defined as the largest dimension in a direction perpendicular to the length direction L1 . The first type of bonding elements preferably has an elongated shape with a length/width-relationship L1 /W1 of at least 2: 1 .

The length L1 of the first type of bonding elements 10 is preferably not more than 7 mm, preferably not more than 4 mm.

The second type of bonding elements 1 1 has a length L2 defined as the largest extension in the CD or at an angle ±10° to the CD, when applicable. The width W2 of the second type of bonding elements 1 1 is defined as the largest dimension in a direction

perpendicular to the length direction L2. The second type of bonding elements preferably has a length/width-relationship L2/W2 of not more than 1 .5: 1 , preferably 1 : 1 . A preferred shape of the second type of bonding elements 1 1 is circular.

The length L1 of the first type of bonding elements 10 is preferably at least 30% larger than the length L2 of the second type of bonding elements 1 1 . The length L1 of the first type of bonding elements 10 is preferably not more than 7 mm, preferably not more than 4mm. The length L2 of the second type of bonding elements is preferably not more than 3 mm.

The part of the perimeter p2 of the second type of bonding elements 10b extending in a direction forming an angle of between 80 and 100° to the machine direction MD is less than of the first type of bonding elements 10a. If one interconnects the end points of such a part of the perimeter p2 forming an angle of between 80 and 100° to the MD direction, by a connection line a2 extending in the CD direction, said connection line a2 should have a length of not more than 1 mm, preferably not more than 0.5 mm. This length a2 is measured in a corresponding manner as for the first type of bonding elements. Apertures 12 are formed in the elastic film in close vicinity of at least some of the first type of bonding elements 10. These apertures 12 are formed by rupture of the elastic film as a result by stretching and extend from the part a1 of the perimeter p1 of the respective bonding element 10 that has a length of at least 1.25 mm and that forms an angle of between 80 and 100° to the MD direction, as referred to above. The apertures 12 are located outside the area of the respective bonding element 10 and are formed due to tensions in the film in the area in close vicinity to the bonding elements. "In close vicinity" to means that the apertures extend from the perimeter p1 of the respective element. The apertures extend substantially in the MD. No apertures are formed in the area of the bonding elements. The apertures render the elastic laminate 20 breathable.

In order to cause apertures 12 to be formed in the described manner as a result by stretching in the MD, the first type of bonding elements 10 has to have a perimeter p1 that has a certain minimum extension in a direction that forms an angle of between 80 and 100° to the stretching direction, i.e. to the MD. This minimum extension is referred to as the length a1 .

One important aspect of the second type of bonding elements 1 1 is that they should limit the extension in the MD of the apertures 12 and thus act as barriers for further rupture of the elastic film. As referred to above the perimeter p2 of the second type of bonding elements 1 1 should have a length a2 of not more than 1 mm, preferably not more than 0.5 mm extending in a direction forming an angle of between 80 and 100° to the machine direction MD. This will minimize or prevent ruptures of the film adjacent the second type of bonding elements 1 1 and make them act as barriers for further extension of the apertures 12 formed adjacent the first type of bonding elements 10.

In order to provide an efficient barrier for undesired further rupture of the film at least one second bonding element 1 1 is located at a distance d of between 1 and 7 mm from the perimeter p1 of a respective first bonding element 10 having a length a1 of at least 1 .25 mm. This distance d is measured in the machine direction MD of the laminate and between the respective perimeters p1 and p2 of the first 10 and second bonding elements 1 1 facing each other. The total number of the second type of bonding elements 1 1 may be at least 10% larger than the total number of the first type of bonding elements 10, preferably at least 50% and more preferably at least 100% larger than the total number of the first type of bonding elements.

As illustrated in Fig. 6 the bonding pattern may comprise bonding areas 13 which are spaced apart. Each bonding area 13 comprises a plurality of first and second type of bonding elements 10 and 1 1 . The bonding areas 13 are separated from adjacent bonding areas by unbonded areas forming bands 14. Each bonding area has a periphery p3, wherein only second type of bonding elements 1 1 are located along the periphery of each bonding area. These second type of bonding elements 1 1 will, as described above, act as barriers preventing the apertures 12 formed in the film to extend into the unbonded areas 14. Each band of unbonded area 14 extends in at least one main direction d1 . Each band may also extend in two main directions d1 and d2, which is the case for the zigzag- extending bands 14 in Fig. 7. Each bonding area 13 in at least a part of the elastic laminate is adjacent to at least two bands 14 of unbonded areas, which separate the respective bonding area from the neighbouring bonding areas. The at least two bands 14 which are adjacent each bonding area extend in at least two different main directions d1 and 62. These two main directions may typically make an angle a to each other that is between 30 and 150°, preferably between 45 and 135 °. Bands 14 may also extend in three or more main directions. In some cases the elastic laminate may in other parts thereof comprise other

configurations of bonding areas and unbonded areas than described above. It is however desired that at least 50% of the surface areas, preferably at least 75% of the surface area of the elastic laminate comprises a bonding pattern having the above described configuration of bonding areas 13 and unbonded areas in the form of bands 14.

The bands 14 may have a minimum width w of at least 2 mm. The minimum width is herein defined as the shortest distance between two neighbouring bonding areas 13. Preferably they have a minimum width w of not more than 10 mm. In the embodiment shown in Fig. 6 each band 14 formed between neighbouring bonding areas 1 1 has one main direction. A first group of bands extend in a first main direction d1 and a second group of bands extend in a second main direction d2. The first and second group of bands 14 cross each other.

In the embodiment shown in Fig. 7 each band 14 has at least two main directions, d1 and d2, and have a zigzag shape or wavy shape. Neighbouring bands 14 extend substantially in parallel with each other. Each bonding area 13 in the embodiment shown in Fig. 6 has the shape of a rhombus or rhomboid. It may also have the shape of a rectangle or square or other suitable polygon shape. Each of said bonding areas preferably has a surface area of at least 1 cm2.

In the embodiment of Fig. 7 the bonding areas 13 form bands of zigzag-shape extending in parallel.

A plurality of bonding areas 13 separated by bands 14 of unbonded areas form a visually recognizable geometric pattern, wherein a series of bonding areas 13 surrounded by unbonded areas form said recognizable pattern.

The effective bonded area within each bonding area 13 is typically between 5 and 40%, preferably between 5 and 30% and more preferably between 10 and 20%. The effective bonded area of the elastic laminate is typically between 3 and 18%. The effective bonded area herein relates to the bonding equipment used for bonding the laminate and is thus measured on the bonding equipment, for example a patterning roll.

In order to measure the effective bonded area the total area of interest A_tot must be determined. This is illustrated in Fig. 10 showing an elastic laminate stretched to the "knee point" (see Tensile strength test below and Fig. 1 1 ). For an elastic laminate comprising an elastic film and two or more nonwoven layers, the elastic film may be laminated to the nonwoven layers in a stretched condition. The "knee point" of the elastic laminate will in such case approximately correspond to the stretched condition of the laminate during bonding, and thus the effective bonded area of the bonding pattern on the laminate stretched to the "knee point" wili approximately correspond to that on the bonding equipment. For measuring the effective bonded area within each bonding area, A_tot is the area circumscribed by the tangents to the outermost bonding elements of the respective bonding area 13.

For measuring the effective bonded area of the laminate, A_tot is the area of one repeating unit of the bonding pattern also including unbonded areas 14 between bonding areas 13 in a repeating unit of bonding pattern. For unbonded areas 14 between groups of repeating units, half of said unbonded area 14 is considered to belong to each repeating unit of the bonding pattern. This is illustrated in Fig. 10.

The bonded area A_bond is measured relating to the bonding equipment used. The bonded area percentage = 100 * A_bond / A_tot The combination of bonding areas 13 separated by unbonded areas in the form of bands 14 extending in at least two main directions d1 and d2 provide an elastic laminate with improved comfort, fit, elastic properties and aesthetical impression, especially for elastic pant diapers. The laminate will adapt to the contours of the wearer and follow the movements of the wearer, since the unbonded areas extending in at least two main directions have an elasticity that are not restricted by bonding elements. The laminate is especially adapted for use in an elastic pant diaper or pant like incontinence garment having an elastic laminate extending over the belly area and/or the hip area, in which the movements of the wearer need to be followed by expansion and retraction of the elastic laminate in different directions.

The invention also refers to an absorbent article comprising the elastic laminate 20. The term "absorbent article" refers to products that are placed against the skin of the wearer to absorb and contain body exudates, like urine, faeces and menstrual fluid. The invention mainly refers to disposable absorbent articles, which means articles that are not intended to be laundered or otherwise restored or reused as an absorbent article after use.

The absorbent article comprising the elastic laminate 20 is preferably a pant-type absorbent article such as a pant diaper, sanitary pant or incontinence pant. Fig. 8 shows an embodiment of a pant-type absorbent article 1 for an infant or an incontinent adult or a sanitary pant. Said pant article typically comprises a chassis 4 including a front panel 5, a back panel 6, a crotch portion 19 and an elastic waistband 7. A core region 3 comprising an absorbent core 2 is located at least in the crotch portion 19 of the article and extends a certain distance into the front 5 and back panels 6. The crotch portion 19 is herewith defined as the narrow part of the article intended to be worn in the wearer's crotch between the legs. In a further embodiment (not shown) the front and back panels are separated from each other and the core region, comprising the absorbent core, bridges the gap between the front and back panels.

The article has a longitudinal direction y and a transverse direction x.

According to one embodiment of the invention the surface area of the absorbent core 2 amounts to no more than 30% of the total surface area of the article, preferably no more than 20%, as measured in a flat state of the article. The term "flat state" herein means in an opened untensioned state in which the side seams are opened and in which any tensioned elastic members have been deactivated.

The elastic laminate 20 may cover the entire article, including the core region 3 and the entire chassis region 4. However according to a preferred embodiment a substantial part of the crotch portion 19 of the article is free from the elastic web material 1 1. A "substantial part" used herein refers to at least 50%, preferably at least 75%. Also the waist region 7 of the chassis region may be free from the elastic laminate 20. The waist region 7 comprises a nonwoven material that is elasticized by elastic members 14, such as elastic threads, contractably affixed between material layers, such as nonwoven materials. Such elastic members 14 may also be arranged around the leg openings of the article. Ultrasonic welds 16, glue strings or the like, join the elastic laminate 1 1 to the elasticized nonwoven in the waist region 7. A nonwoven material 18 may be arranged on the garment-facing side of the liquid- impervious backsheet 9 in the crotch portion of the article. The nonwoven material 18 is joined to the elastic laminate 20 by means of ultrasonic welds 17, glue strings or the like.

The elastic laminate 20 is preferably arranged as an outside coversheet material as well as inner coversheet material over at least a substantial part of the front region 5 of the chassis 4, which during use is intended to be applied against the stomach of the wearer, except for the waist region 7. A "substantial part" used herein means at least 50% of the surface area, preferably at least 75%, of the surface area of the front region 5 of the chassis 4. It is further preferred that the elastic laminate 20 is arranged as an outside coversheet material as well as inner coversheet material over both the front 5 and back regions 6 of the chassis 4. Thus no additional backsheet or topsheet materials are required and the elastic web material constitutes the sole component of in these parts of the chassis 4. In at least 20%, preferably at least 25%, more preferably at least 30% and most preferably at least 40% of the total surface area of the article, as seen in a flat state, as referred to above, the elastic laminate 20 constitutes the sole component of the chassis.

The outer coversheet covering the front and back panels 5 and 6 of the chassis 4 comprises an elastic laminate material 20, which is elastic at least in the transverse x- direction of the article. The elasticity in the x-direction should be at least 30%, preferably at least 50%, more preferably at least 70%, as measured by the Elasticity test specified below. The transverse x-direction of the article herewith corresponds to the MD of the elastic laminate described above. For an elastic laminate used as a front 5 and/or back panel 6 in a pant-type absorbent article it is an advantage that the laminate comprises at least three layers, viz. first and second outer fibrous layers, which are chosen so that they, in combination with the inner elastic film layer, give the material high resistance to puncture, in order to prevent penetration by finger nails for example. They also provide a soft and cloth-like feel to the laminate. Examples of suitable materials are carded webs and spunbond materials. The basis weight of the fibrous material layers should be between 10 and 35 g/m², preferably between 12 and 30 g/m², more preferably between 13 and 25 g/m². Examples of suitable polymers used in the fibrous materials are polyethylene, polyesters, polypropylene and other polyolefin homopolymers and copolymers. Natural fibres, for example cotton, may also be used as long as they provide the required properties. A mixture of polymers can contribute to a higher flexibility of the nonwoven layer, and through this, give the nonwoven material a higher elongation at maximum load. A mixture of polyethylene and polypropylene polymers has proved to provide good results in this respect. A mixture of fibers of different polymers is also possible. The middle film layer preferably has a basis weight between 20 and 80 g/m², preferably between 20 and 60 g/m². The film may be of any suitable elastic polymer, natural or synthetic. Some examples of suitable materials for the elastic film are low crystallinity polyethylenes, metallocene-catalyzed low crystallinity polyethylene, ethylene vinyl acetate copolymers (EVA), polyurethane, polyisoprene, butadiene-styrene copolymers, styrene block copolymers, such as styrene/isoprene/styrene (SIS), styrene/butadiene/styrene (SBS), or styrene/ethylene-butadiene/styrene block copolymer. Blends of these polymers may also be used as well as other modifying elastomeric or non-elastomeric materials. One example of a suitable film is a three-layer elastomeric film of PE-SEBS-PE.

The total basis weight of the laminate is preferably 100 g/m² or less, more preferably not more than 90 g/m².

The article comprises a liquid permeable topsheet 8 and a liquid impermeable backsheet 9 covering at least the core region 3. The absorbent core 2 is enclosed between the topsheet 8 and the backsheet 9.

The liquid permeable topsheet 8 can consist of a nonwoven material, e g spunbond, meltblown, carded, hydroentangled, wetlaid etc. Suitable nonwoven materials can be composed of natural fibers, such as woodpulp or cotton fibres, manmade fibres, such as polyester, polyethylene, polypropylene, viscose etc. or from a mixture of natural and manmade fibres. The topsheet material may further be composed of tow fibres, which may be bonded to each other in a bonding pattern, as e.g. disclosed in EP-A-1 035 818. Further examples of topsheet materials are porous foams, apertured plastic films etc. The materials suited as topsheet materials should be soft and non-irritating to the skin and intended to be readily penetrated by body fluid, e.g. urine or menstrual fluid. The topsheet may be different in different parts of the absorbent article.

The liquid impervious backsheet 9 covering the core region 3 on the garment-facing side of the core is of a liquid impervious material, such as a thin plastic film, e.g. a polyethylene or polypropylene film, a nonwoven material coated with a liquid impervious material, a hydrophobic nonwoven material, which resists liquid penetration or a laminate comprising plastic films and nonwoven materials. The core region backsheet material 9 may be breathable so as to allow vapour to escape from the absorbent core, while still preventing liquids from passing therethrough. Examples of breathable backsheet materials are porous polymeric films, nonwoven laminates from spunbond and meltblown layers, laminates from porous polymeric films and nonwovens. The backsheet 9 is preferably inelastic. The "absorbent core" is the absorbent structure disposed between the two covers of the absorbent article. The absorbent core 2 can be of any conventional kind. Examples of commonly occurring absorbent materials are cellulosic fluff pulp, tissue layers, highly absorbent polymers (so called superabsorbents), absorbent foam materials, absorbent nonwoven materials or the like. It is common to combine cellulosic fluff pulp with superabsorbent polymers in an absorbent core. Superabsorbent polymers are water- swellable, water-insoluble organic or inorganic materials capable of absorbing at least about 20 times its weight and in an aqueous solution containing 0.9 weight percent of sodium chloride. Organic materials suitable for use as a superabsorbent material can include natural materials such as polysaccharides, polypeptides and the like, as well as synthetic materials such as synthetic hydrogel polymers. Such hydrogel polymers include, for example, alkali metal salts of polyacrylic acids, polyacrylamides, polyvinyl alcohol, polyacrylates, polyacrylamides, polyvinyl pyridines, and the like. Other suitable polymers include hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, and isobutylene maleic anhydride copolymers and mixtures thereof. The hydrogel polymers are preferably lightly crosslinked to render the material substantially water insoluble. Preferred superabsorbent materials are further surface crosslinked so that the outer surface or shell of the superabsorbent particle, fiber, flake, sphere, etc. possesses a higher crosslink density than the inner portion of the superabsorbent. The superabsorbent materials may be in any form suitable for use in absorbent composites including particles, fibers, flakes, spheres, and the like.

A high absorption capacity is provided by the use of high amounts of superabsorbent material. For an absorbent core comprising a matrix of hydrophilic fibers, such as cellulosic fibers, and superabsorbent material, the proportion of superabsorbent material is preferably between 10 and 90% by weight, more preferably between 30 and 70% by weight.

It is conventional in absorbent articles to have absorbent cores comprising layers of different properties with respect to liquid receiving capacity, liquid distribution capacity and storage capacity. The thin absorbent bodies, which are common in for example baby diapers and incontinence guards, often comprise a compressed mixed or layered structure of cellulosic fluff pulp and superabsorbent polymers. The size and absorbent capacity of the absorbent core may be varied to be suited for different uses such as for infants or for adult incontinent persons.

The absorbent core 2 may further include an acquisition distribution layer placed on top of the primary absorbent body and which is adapted to quickly receive and temporarily store discharged liquid before it is absorbed by the primary absorbent core. Such acquisition distribution layers are well known in the art and may be composed of porous fibrous waddings or foam materials.

Although the elastic laminate according to the invention primarily is intended to be used in pant-type absorbent articles, in which the elastic laminate extends all the way between the side seams of the article, in at least one of the front and back panels, it may also be used to form for example elastic side panels in an absorbent article. Fig. 9 illustrates a pant- type absorbent article 1 comprising elastic side panels 21 . The article further comprises a front body panel 22 and a back body panel 23 and a crotch portion 24. The front and back body panels as well as the crotch portion is generally comprised of a liquid impermeable backsheet 24, a liquid permeable topsheet 25 and an absorbent core 26 located between the backsheet 52 and the topsheet 25. The topsheet, backsheet and absorbent core may be of the same kind as referred to with respect to the embodiment of Fig. 7. The backsheet 24 may further comprise a layer of nonwoven material laminated to a film layer, in which case there is provided a more cloth-like and garment-like feel than is typically obtained with a film backsheet only.

The elastically extensible side panels 21 are provided to ensure more comfortable and contouring fit. The elastic side panels 21 or at least parts thereof may comprise the elastic laminate 20 according to the invention, and as described with reference to the

embodiment of Fig. 8. Leg elastics and waist elastic region may also be provided to enhance the fit around the legs and waist, respectively.

TEST METHODS

Elasticity test

The method measures how an elastic material behaves at repeated load and unload cycles. The sample is stretched to a predetermined elongation and a cyclic movement between 0 and said predetermined elongation is performed. Desired load and unload forces are recorded. The permanent, i.e. remaining, elongation of the relaxed material is measured. A tensile tester, Lloyd LRX, able to perform cyclic movements and equipped with a printer/plotter or software presentation is used. The sample is prepared by cutting it to a width of 25.4 mm and a length that is preferably 50 mm longer than the distance between the clamps in the tensile tester. The tensile tester is calibrated according to the apparatus instructions. The parameters needed for the test (load and unload forces) are adjusted to:

• Crosshead speed: 500 mm/min

• Clamp distance: 50 mm

• Preload: 0.05 N

The sample is conditioned at least 4h in 50% RH ±5% RH and 23°C ±1 °C and is placed in the clamps according to the marks and it is made sure that the sample is centred and fastened perpendicularly in the clamps. The tensile tester is started and three cycles between 0 and the predetermined elongation, equal to the highest defined 1 ^st load, are performed. Before the last cycle, the sample is relaxed for 1 minute, then the permanent elongation is measured by stretching the sample until a force of 0.1 N is detected and the elongation is read.

An elastic material is defined as a material having a permanent elongation after relaxation of less than 10% after the material has been subjected to an elongation of 30%. An elongation of 30% means an elongation to a length that is 30% longer than the initial length of the sample. Thus a material having an elasticity of at least 30% is defined as that the material should have a permanent relaxation after elongation of less than 10% after being exerted to an elongation of 30% in the tensile tester above. A material having an elasticity of at least 50% is defined as that the material should have a permanent relaxation after elongation of less than 10% after being exerted to an elongation of 50% in the tensile tester above, etc.

A non-elastic material has a permanent elongation after relaxation of more than 10% after having been subjected to an elongation of 30%. Tensile strength (Reference: ASTM D 882)

The method measures tensile strength and elongation of different elastic materials. The tensile strength and elongation of a well-defined test piece is tested by means of a tensile tester.

Apparatus: Instron 4301

• Tensile tester connected to a computer

• Crosshead speed: 500 mm/min

· Clamp distance: 50 mm

Sample preparation: Test samples are cut from the entire width of the material. The width of the sample shall be 25.4 mm and the length at least 50 mm longer than the clamp distance if possible. It is of importance that the edges of the sample are even and without break notches. The samples are conditioned for at least 4h in 50%RH ± 5% RH and 23°C ± 2°C before testing.

Procedure: The tensile tester is calibrated according to the apparatus instructions and set to zero. The sample is mounted and it is ensured that it is not obliquely or unevenly fastened. The material is prevented from slipping by using clamps covered with galloon or similar material. The tensile tester is started, and stopped after the material has broken (if not automatically controlled). Measurements resulting from premature failures (i.e. the sample breaks at the clamp, or is damaged during preparation) are ignored if possible. The following results are expressed by the tensile tester/computer:

- Maximum force, N/25.4mm

Elongation at maximum force, %

Break force, N/25.4mm

Elongation at break force, %

- Knee point, N/%

Fig. 1 1 shows the behaviour of a laminate according to the present invention under stretching at a constant strain. The laminate comprises a multilayer MD elastic film having a core layer of SEBS and skin layers of PP, basis weight 30 gsm, and a PP spunbond nonwoven layer on both sides of the film, each spunbond nonwoven layer having a basis weight of 16 gsm.

From zero elongation, the laminate exhibits elastic behaviour in a region up to around a "knee point", after which, the force increases rapidly. The knee point is defined as the first point on the curve at which the gradient becomes greater than 0.4N/%. The laminate shown in Fig. 1 1 is elastic up to about 71 % elongation.

The applied force eventually reaches a maximum (the "maximum force"), at which point the gradient of the curve is zero. The force then drops as the material fails.

Claims

An elastic laminate material (20) comprising at least one elastic film layer and at least one nonwoven layer, said elastic film layer and said nonwoven layer being bonded together in a bonding pattern comprising a plurality of bonding elements (10, 1 1 ), in which said elastic film and said nonwoven are fused together, said elastic film being in a stretched condition during bonding in a machine direction (MD), characterized in that said bonding pattern comprises at least two different types of bonding elements, wherein a first type of bonding elements (10) have a perimeter (p1 ), said perimeter having a part forming an angle of between 80 and 100° to the MD direction, said part having a length of at least 1.25 mm as measured perpendicular to the MD direction in the form of an imaginary connection line (a1 ) interconnecting the end points of such a part of the perimeter (p1 ) forming an angle of between 80 and 100° to the MD direction, and a second type of bonding elements (1 1 ) having a perimeter (p2), said perimeter having a part forming an angle of between 80 and 100° to the MD direction, said part having a length of not more than 1 mm as measured perpendicular to the MD direction in the form of an imaginary connection line (a2) interconnecting the end points of such a part of the perimeter (p2) forming an angle of between 80 and 100° to the MD direction, and wherein apertures (12) being formed in the elastic film in close vicinity of at least some of the first type of bonding elements (10), said apertures being caused by rupture of the elastic film as a result by stretching and extend from said part of perimeter (p1 ) of the respective bonding element forming an angle of between 80 and 100° to the MD direction, and are located outside the area of the respective bonding element.

The elastic laminate as claimed in claim 1 , characterized in that said first type of bonding elements (10) have an elongated shape with a length/width (L1/W1 )- relationship of at least 2: 1 .

The elastic laminate as claimed in claim 1 or 2, characterized in that said secon type of bonding elements (1 1 ) have a length/width (L2A/V2) relationship of not more than 1 .5: 1 , preferably 1 : 1 .

4. The elastic laminate as claimed in any of the preceding claims, characterized in that the length (L1 ) of the first type of bonding elements (10) is at least 30% larger than the length (L2) of the second type of bonding elements (1 1 ). 5. The elastic laminate as claimed in any of the preceding claims, characterized in that the length (L1 ) of the first type of bonding elements is not more than 7mm, preferably not more than 4mm.

The elastic laminate as claimed in any of the preceding claims, characterized in that the length (L2) of the second type of bonding elements is not more than 3 mm.

The elastic laminate as claimed in any of the preceding claims, characterized in that said part of the perimeter of the first type of bonding elements (10) forming an angle of between 80 and 100° to the MD direction has a length of between 1 .5 and 2 mm as measured perpendicular to the MD direction in the form of an imaginary connection line (a1 ) interconnecting the end points of such a part of the perimeter (p1 ) forming an angle of between 80 and 100° to the MD direction.

The elastic laminate as claimed in any of the preceding claims, characterized in that said length (a2) of the perimeter (p2) of said second type of bonding elements (1 1 ) extending in a direction forming an angle of between 80 and 100° to said machine direction (MD) is a continuous length of not more than 1 mm, preferably not more than 0.5mm.

The elastic laminate as claimed in any of the preceding claims, characterized in that at least one second bonding element (1 1 ) is located at a distance (d) of between 1 and 7mm from said perimeter of a respective first bonding element (10) having a length (a1 ) of at least 1.25 mm, said distance being measured in the machine direction (MD) of the laminate and between the respective perimeters of the first and second bonding elements.

10. The elastic laminate as claimed in any of the preceding claims, characterized in that the total number of the second type of bonding elements (1 1 ) is at least 10% larger than the total number of the first type of bonding elements (10).

1 1 . The elastic laminate as claimed in claim 8, characterized in that the total number of the second type of bonding elements (1 1 ) is at least 50% and preferably at least 100% larger than the total number of the first type of bonding elements (10).

12. The elastic laminate as claimed in any of the preceding claims, characterized in that the laminate comprises at least two nonwoven layers, wherein the elastic film is located between the nonwoven layers. 13. The elastic laminate as claimed in any of the preceding claims, characterized in that said bonding pattern comprises bonding areas (13) spaced apart, each bonding area (13) comprising a plurality of first and second type of bonding elements (10, 1 1 ) and having a periphery (p3), said bonding areas are separated from adjacent bonding areas by unbonded areas (14), wherein only second type of bonding elements (1 1 ) are located along the periphery (p3) of each bonding area.

14. The elastic laminate as claimed claim 13, characterized in that said unbonded areas form bands (14), each band extending in at least one main direction (d 1 ) and wherein at least a main part of the bonding areas each is adjacent to at least two bands of unbonded areas, said at least two bands extending in at least two different main directions (d 1 , d2).

1 5. An absorbent article comprising an outer cover, an inner bodyside liner and an absorbent core located between the outer cover and the inner bodyside liner, characterized in that the absorbent article includes an elastic laminate as claimed in any of claims 1 -15.

16. The absorbent article as claimed in claim 15, said absorbent article being a pant- type article comprising front and back body panels, said article having a longitudinal direction (y) and transverse direction (x), characterized in that at least a part of said front and/or back body panels comprises said elastic laminate as a sole component.

17. The absorbent article as claimed in claim 16, characterized in that said elastic laminate extends the entire width, as seen in the transverse direction (x), of at least one of the front and back body panels.

1 8. The absorbent article as claimed in claim 15, said absorbent article being a pant- type article comprising elastic side panels, characterized in that at least a part of said elastic side panels comprises said elastic laminate as a sole component.