Absorbent article

Abstract

A disposable absorbent article in the form of a pant diaper, comprises a chassis having a front panel and a back panel of chassis material, that meet at the hip to define a waist opening. A crotch panel extends between the front panel and the back panel to define leg openings. A tear line is provided in the chassis, extending between the waist opening and the leg opening, to facilitate removal of the pant diaper. The tear line comprises a concatenation of fused curvilinear line segments aligned with the tear line. As a result of the fusing of the chassis material, it can be easily torn to open the diaper.

Description

Absorbent articleField

[0001] The present disclosure relates to disposable absorbent articles in the form of pant diapers that are intended to be pulled on and which may be torn to facilitate removal. The disclosure relates in particular to improvements in such tear lines by which the pant diaper can be more easily torn.Background

[0002] Infants and young children wear disposable articles such as diapers to absorb and contain bodily exudates. In the first months, such diapers are generally wrapped around and secured with releasable fasteners. As a child ages, toilet training will commence and the child will make the transition to wearing underwear. During this training process, pant diapers may be used in order to accustom the child to wearing underwear. For adults, pant diapers may also be used in various circumstances both in long term care and for temporary conditions.

[0003] Pant diapers are usually elasticated and are pulled on and can be pulled off as with conventional underwear. Nevertheless, removing a soiled diaper by pulling it down the legs is less preferred. For this reason, pant diapers are often designed with front and back panels that are joined together in a manner that they can be removed by separating the front and back panels at the side seams.

[0004] In some articles, the front and back panels are joined at a seam and separation takes place by opening the seam e.g. by disrupting a weld or releasing an adhesive. US5163932 provides an example of a pants diaper where the front and back panels are welded together but where the weld can be disrupted by pulling the panels apart. Alternatively, an additional frangible location may be provided, separate from the seam, where tearing of the diaper material can take place. US20240000638 provides an example of such frangible zones.

[0005] It will be understood that the different approaches have different advantages and disadvantages. Providing for seams that can be opened avoids the requirement of an additional step to form a frangible region. However, the strength of the seam may be compromised and / orthe manufacture of the seam may be more complicated. Additionally, the location of the seam e.g. at the hip may not correspond to the most convenient location forgrasping the diaper in orderto cause separation. On the other hand, a separate frangible region may be conveniently located on the front panel but requires additional manufacturing steps. Furthermore, since pant diapers are generally elasticated, the frangible region crosses the elastic region, which may complicate the design requirements of both the elastic material and the frangible region.

[0006] Existing frangible regions have been made in various ways, including cutting, perforating, melting and combinations of the above. Although some success has been achieved with such frangible regions, most have been found difficult or inconvenient to open.

[0007] It would be desirable to find a solution that allowed convenient removal of a pant diaper that overcame some or all of the above-mentioned drawbacks.Summary

[0008] This object may be at least partially achieved with an absorbent article in accordance with claim 1 . Further embodiments are set out in the dependent claims and in the following description.

[0009] Accordingly, a disposable absorbent article in the form of a pant diaper, comprises a chassis having a front panel and a back panel of chassis material, that meet at the hip to define a waist opening. A crotch panel extends between the front panel and the back panel to define leg openings. A tear line is provided in the chassis, extending between the waist opening and the leg opening, to facilitate removal of the pant diaper, wherein the tear line comprises a concatenation of fused curvilinear line segments aligned with the tear line. As a result of the fusing of the chassis material, it can be easily torn to open the diaper. The curvilinear shape in the direction of the tear line has been found to facilitate the tear in following the tear line, while ensuring that adequate chassis material remains to preserve the strength of the chassis. In this context, aligned with the tear line is intended to denote that each line segment has an extent in the direction of the tear line that is greater than an extent perpendicular to the tear line.

[0010] The curvilinear line segments may have any appropriate overall length, subject to the above requirement that they extend in the direction of the tear line. They may all have the same length or vary in length. The line segments may have a length of at least 7 mm, such as at least 10 mm or more than 15 mm. The number of curvilinear line segments will also depend on their individual length and the length of the tear line. The tear line may comprise between 1 and 100 line segments, such as between 10 and 30 line segments. The tear line may comprise a continuous line segment between the waist opening and the leg opening. The continuous line segment may be formed of overlapping individual curvilinear line segments.

[0011] Furthermore, the curvilinear line segments may have any appropriate width. Each line segment may have a maximum width of less than 4 mm or less than 2 mm or less than 1 mm and may be larger than 0.2 mm. The width of the line segment may be constant or at least substantially constant along its length. Alternatively, the width may vary such as the case of a crescent shaped line segment. Additionally, the width of the line segments may be such that a length to width ratio is greater than 4, or greater than 6 or greater than 10. The line segment(s) may have a larger width at the start and ends of the tear line, such as at the waist and / or leg openings, than the widths of rest of the line segments to facilitate the start of the tearing. The width of the line segments may be at least 30% larger at the waist and / or leg openings than the widths of rest of the line segments along the tear line.

[0012] In the present context, concatenation is intended to denote that the line segments are arranged in series or as a chain, extending in the direction of the tear line. The individual line segments may be linked together, interleaved, cross or overlap but collectively form a line extending between the waist opening and the leg opening. An end of a first line segment may be aligned with and spaced from an end of an adjacent line segment. The line segments may be arranged in overlapping relation. This may be preferred when the chassis comprises elastic threads that crossthe tear line. The overlapping line segments can ensure that each elastic thread is crossed by at least one of the line segments.

[0013] The line segments may overlap such that a first line segment overlaps an adjacent line segment by at least 10 %, or at least 20 %, or at least 40 % of the length of the first line segment. The overlapping line segments may run parallel to each other in the overlap region. When the degree of overlap is high, the line segments may effectively form two parallel interrupted lines, which together define the tear line.

[0014] The line segments may touch or cross or otherwise join to the extent that individual line segments can still be identified. The line segments may be distanced from each other by a minimal spacing of at least 1 mm, or at least 2 mm or at least 3 mm. In this manner, unfused chassis material remains between the line segments, which ensures the strength and integrity of the chassis.

[0015] In the present context, curvilinear is intended to denote that the line segment has at least one curvature. The line segment may be continuously curved or have curved sections connecting straight sections. The line segments may each comprise a single curve, which may be e.g. a crescent, a semi-circle, a sine-wave section or a parabola. Alternatively, at least some line segments may comprise multiple curves e.g. comprising any of the above curves linked together in series. The tear line may comprise a mixture of line segments with both single curves and multiple curves e.g. alternating and / or overlapping.

[0016] In addition to the above defined curvilinear line segments, the tear line may comprise additional segments of fused chassis material that do not meet the definition of curvilinear or which are not concatenated or aligned with the tear line. The additional segments may be located to one or both sides of the line segments and may assist in guiding the tear direction during tearing of the chassis at the tear line. The additional segments may be positioned at gaps or interruptions between the line segments and can facilitate tearing of elastic material that may be present. The additional segments may be fused to the same degree as the line segments or to a lesser or greater degree. The additional segments may be of any appropriate shape, including straight lines, circles, ovals, chevrons, lenticular.

[0017] The pant diaper may be of conventional construction, with the front panel and the back panel being joined together at a seam. They may be joined by conventional procedures, including welding, stitching, adhesives and the like. The seam may be a side seam e.g. located at the hip such that the front panel has a similar length to the back panel at the waist opening. The tear line may be spaced from the side seam. This ensures that the location of the tear line does not interfere with the seam and that on tearing the tear line, the seam does not interfere with this action. It also allows the tear line to be located at the most convenient location fortearing to take place, preferably on the front panel. The tear line may be spaced from the seam by at least 5 mm or at least 10 mm or more than 20 mm, and may be less than 40 mm. It will be understood that although reference has been given to a tear line, there will generally be two tear lines, each intersecting one of the leg openings. There may also be more than two tear lines.

[0018] The tear line may also be oriented in any direction that is convenient both for manufacture and use. It may be linear, a straight line being the shortest path between two points. It may beperpendicular to the waist opening e.g. at a shortest distance to the leg opening. Alternatively, the tear line may be curved or change direction. Depending on the location of the tear line and on the overall dimensions of the pant diaper, the tear line may have a length of at least 50 mm or at least 100 mm. The tear line may intercept a waist edge and / or a leg edge of the chassis. In particular, a fused line segment may intercept the waist edge in order to provide a location at which tearing can commence and may intercept the leg edge to provide a complete tear of the tear line through the panel. It will be understood that users may prefer to attempt to tear at an edge location such as at the waist edge, although tearing at a mid-point of the tear line e.g. by inserting the fingers may also be a method of opening.

[0019] During tearing, it will be understood that a single tear may travel from line segment to line segment. Nevertheless, prior to tearing, the tear line may be defined by the maximum lateral extent of the line segments in a direction perpendicular to the length direction of the tear line. During use, the tear may be expected to remain within this envelope. The tear line may thus be a strip having an overall width of between 2 mm and 20 mm, such as between 3 mm and 10 mm. It will however not be referred to as a tear strip as this term is usually used to refer to a removable strip between two tear lines.

[0020] The line segments may be fused in any appropriate manner. A preferred method uses ultrasound to impart energy to the chassis material which is thus caused to melt and can be fused together by the application of pressure. The line segments can be formed using e.g. a rotating sonotrode or in a stamping or reciprocating process. The line segments may be fused to completely melt and / or denature the chassis material but may not cause perforation of the chassis material. Furthermore, the line segments may be fused and / or visible from either the inside or the outside of the chassis or from both sides. In general, the line segments may be at least visible from the outside of the chassis in order that a user can identify the position at which tearing should occur.

[0021] As a result of the fused line segments, the chassis material is weakened and can be torn apart on exerting a force perpendicular to the tear line. The tear line may be constructed such that the circumferential tear strength across the tear line is between 10 N / 25 mm and 35 N / 25 mm, such as between 10 N / 25 mm and 25 N / 25 mm, as measured according to the test procedure set out below.

[0022] As noted above, the diaper should be suitably elastic, especially around the waist and leg openings, in order to ensure a snug fit on users of different sizes and prevent leakage. The chassis material may comprise circumferentially extendable elastic material, such as elastic nonwoven material or a laminate of nonwoven materials and elastic threads. This may be present at least at the location of the tear line and the line segments can thus assist in tearing the elastic material. Any suitable elastomeric material may be used including elastomeric films, elastic scrim, heat shrinkable elastic materials, elastomeric film laminates, elastomeric stretch laminates, mechanically stretched pretensioned stretch laminates. The elastic threads may be natural or synthetic rubber, including SPANDEX TM, LYCRA TM, or other materials. Examples of elastic non-woven materials may be as given in WO2019070171 . It will be understood that the degree to which the elastic material is denatured at the line segment will depend on the elastic material properties. Most elastic materialsare cross-linked and do not melt when exposed to heat. They nevertheless may partially lose their elastic properties and become more brittle and susceptible to rupture.

[0023] The chassis material may comprise fusible polymeric material, at least at the location of the tear line. The fusible polymeric material may be any suitable material for forming the chassis that is susceptible to melting to form the line segments and create a structure that will act as a tear line. The fusible polymeric material may comprises polyolefin material and may be in the form of an extruded film or a non-woven fibrous material. As noted above, the elastic material of the chassis may not itself melt and at each line segment it may only be the polymeric material that is fused. In some cases, the chassis material may comprise multiple layers of fusible polymeric material, which are fused togetherto form the line segment. In cases where the elastic material is provided between layers of fusible polymeric material, the layers of fusible polymeric material may be fused around the elastic material. In that case, the elastic material may not itself be significantly denatured and may still maintain its elastic properties.

[0024] The depth to which the line segments are fused will depend on the amount of energy imparted and / or the pressure exerted on the chassis material. The setting of the tooling’s need to be adapted according to the materials of the articles. The line segments may have a thickness that is less than 30% or less than 20% or less than 15% of the thickness of the adjacent unfused chassis material. It will be understood that this will also at least partially depend on the nature of the chassis material as discussed above. The fusing of elastic threads causes them to weaken or break at the fused location providing for an improved tearing of tear line.

[0025] The absorbent article may be an otherwise conventional pant diaper having dimensions and materials according to the intended use. The crotch panel may be integrally formed with the front panel and back panel or may be joined between the front panel as a separate element. The crotch panel may comprise a topsheet, a backsheet and an absorbent core provided between the topsheet and the backsheet. At least the backsheet may be formed of a material corresponding to an outer surface of the front and back panels. The crotch panel may be of any suitable shape, including rectangular and hour glass shapes. It may be provided with elastics and side-panels to assist in sealing around the leg openings.

[0026] The backsheet may have a laminate structure comprising a liquid barrier sheet and a nonwoven layer arranged on top of each other, wherein the nonwoven layer is arranged at an outer side of the crotch panel, facing away from a wearer of the absorbent article when worn. The liquid barrier sheet ensures that liquid cannot penetrate outwards, while the non-woven layer can provide for a soft touch imitating cloth underwear. It can also provide a good printing surface forthe provision of designs.

[0027] The liquid barrier sheet may extend over the entire length, in the direction from the front panel towards the back panel, of the portion of the crotch panel arranged between the front panel and the back panel. The liquid barrier sheet may further extend over at least a portion of the front panel and over at least a portion of the back panel. The nonwoven layer may extend at least over the entire length, in the direction from the front panel towards the back panel, of the portion of the crotch panel arranged between the front panel and the back panel. The nonwoven layer may notextend over the front panel over a length, in the direction from the front panel towards the back panel, of more than 40 mm. The nonwoven layer may not extend over the back panel over a length, in the direction from the front panel towards the back panel, of more than 40 mm. The width, in the direction perpendicularto the direction from the front panel towards the back panel, of the nonwoven layer may be smaller than the width, in the direction perpendicular to the direction from the front panel towards the back panel, of the liquid barrier sheet.

[0028] The nonwoven layer may be made of thermoplastic polymer material fibers or filaments. The nonwoven layer may be formed by a variety of different processes, such as spunbonding, airlaying, meltblowing or bonded carded web formation processes. In particular, the nonwoven layer may be made of an SMS (spunbond / meltblown / spunbond) or SS (spunbond / spunbond) nonwoven material of polypropylene or bicomponent fibers of polypropylene and polyethylene, or of a combination of such materials. The nonwoven layer may have a basis weight in the range of 10 g / m2to 20 g / m2.

[0029] The liquid barrier sheet may be made of a plastic material, for example a thermoplastic film material, and / or a nonwoven material. For example, the liquid barrier sheet may be formed as a plastic layer, e.g., a thermoplastic layer, or a plastic film, e.g., a thermoplastic film. Forming the liquid barrier sheet of a plastic material, in particular, a thermoplastic film material, allows for a particularly good printability of the liquid barrier sheet.

[0030] The liquid barrier sheet may be a liquid impermeable, breathable or non-breathable layer. The liquid barrier sheet may consist of a single layer or have a laminate structure with a plurality of layers, e.g., two or more layers, three or more layers, or four or more layers. The layers of the liquid barrier sheet may be laminated, bonded or attached to each other, for example, by thermomechanical bonding, such as thermosealing, ultrasonic bonding, such as ultrasonic welding, an adhesive or adhesives, stitching or the like.

[0031] In particular, the liquid barrier sheet may be a breathable microporous film. The microporous film may be made of a material comprising at least two basic components, namely a thermoplastic elastomeric polyolefin polymer and a filler. These components and additional other components can be mixed together, heated and subsequently extruded into a mono-layer or multilayer film using any one of various film-producing processes, such as cast embossed, chill and flat cast, and blown film processes.

[0032] On a dry weight basis, based on the total weight of the microporous film, the film may include from approximately 30 weight-% to approximately 60 weight-% of the thermoplastic elastomeric polyolefin polymer, or blend thereof, and from approximately 40 weight-% to approximately 70 weight-% of the filler. Other components, such as additives and / or ingredients, for example, antioxidants and / or stabilisers and / or pigments, may be included in the film.

[0033] The filler may consist of one or more materials selected from calcium carbonate (CaCOs), various kinds of clay, silica (Si02) , alumina, barium carbonate, sodium carbonate, magnesium carbonate, talc, barium sulphate, magnesium sulphate, aluminium sulphate, titanium dioxide (Ti02), zeolites, cellulose-type powders, kaolin, mica, carbon, calcium oxide, magnesium oxide, aluminium hydroxide, pulp powder, wood powder, cellulose derivatives, chitin and chitinderivatives. A suitable coating, such as, for example, stearic acid, may be applied to the filler particles.

[0034] The liquid barrier sheet may have a basis weight in the range of 8 g / m2to 22 g / m2, or 9 g / m2to 20 g / m2, or 10 g / m2to 18 g / m2.

[0035] The topsheet of the crotch panel is arranged to face the wearer of the absorbent article when worn. The topsheet is a liquid permeable layer adapted to allow a liquid, such as urine or other bodily fluids, to pass through.

[0036] The topsheet may consist of a single layer or have a laminate structure comprising a plurality of layers, for example, two or more layers. The layers may be made of the same material, or some or all of the layers may be made of different materials. The layer of the topsheet or, for the case of a laminate structure, one, some or all of the layers of the topsheet may be made of a single material or have plural portions made of different materials, e.g., within different parts of the wearerfacing surface of the topsheet.

[0037] The layer of the topsheet or, for the case of a laminate structure, one, some or all of the layers of the topsheet may be a nonwoven material, a perforated plastic film, a plastic or textile mesh, or a liquid permeable foam layer.

[0038] The layer of the topsheet or, for the case of a laminate structure, one, some or all of the layers of the topsheet may be, for example, a hydrophilic, non-apertured nonwoven web of fibers, such as natural fibers, e.g., cotton or pulp fibers, synthetic fibers, e.g., polyester or polypropylene fibers, or a combination of these fibers.

[0039] The topsheet may have a basis weight in the range of 10 g / m2to 25 g / m2.

[0040] The absorbent core is provided between the topsheet and the backsheet to absorb the liquid, such as urine or other bodily fluids, which has passed through the topsheet. The absorbent core may be made of any suitable absorbent or liquid uptake material, such as one or more layers of cellulose fluff pulp, foam, fiber waddings or the like.

[0041] The absorbent core may contain fibers or particles of absorbent polymer material, in particular, superabsorbent material. Superabsorbent materials have the ability to absorb and retain large quantities of liquid upon formation of a hydrogel. For example, the superabsorbent material may be surface cross-linked, partially neutralised polyacrylates .

[0042] The superabsorbent material, e.g., the superabsorbent fibers or particles, may be mixed with other absorbent or liquid uptake material or materials, such as cellulose fluff pulp, and / or arranged in pockets or layers in the absorbent core. The ratio of superabsorbent material and pulp in the absorbent core may be 0% to 80% pulp fibers and 100% to 20% superabsorbent material.

[0043] The absorbent core may further comprise components for improving the properties of the absorbent core. For example, the absorbent core may comprise a binder or binders, such as binder fibers, and / or a liquid-dispersing material or materials, and / or a liquid acquisition material or materials etc.

[0044] The wearable disposable absorbent article may comprise more than one absorbent core, e.g., two absorbent cores. For example, the absorbent article may comprise an upper absorbentcore and a lower absorbent core having different sizes and properties, wherein the upper absorbent core is arranged closer to the wearer of the absorbent article when worn.Brief description of the drawings

[0045] A disposable absorbent article according to the present disclosure will be described by way of example, with reference to the attached drawings, in which:

[0046] Fig. 1 shows a front view of an exemplary pants diaper comprising a tear line;

[0047] Fig. 2 shows a top view of the diaper of Fig. 1 in a flat laid-out state with the joints between the rear side and the front side removed;

[0048] Fig. 2A shows part of the tear line of Figure 2;

[0049] Fig. 3 is a cross-sectional view through the diaper of Fig. 2 in the direction Ill-Ill;

[0050] Figure 4 shows a cross-section taken through part of the tear line in Figure 2A in the direction IV-IV;

[0051] Figure 5 shows different tear lines with curvilinear line segments; and

[0052] Figure 6A and 6B shows strengths of different tear lines from Example 1 .Description

[0053] Different aspects of the present disclosure will be described more fully hereinafter with reference to the enclosed drawings. The absorbent undergarment disclosed herein can, however be realized in many different forms, such as different sizes and absorption levels, and should not be construed as being limited to the aspects set forth herein.

[0054] Fig. 1 illustrates a pant-type absorbent article 1 according to the present disclosure in the form of a pant diaper. The pant diaper 1 comprising a chassis 2 having a front panel 3 and a back panel 4 of chassis material, that meet at the hip to define a waist opening 6, and a crotch panel 10 extending between the front panel 3 and the back panel 4 to define leg openings 12. The front panel 3 and back panel 4 comprise elasticated chassis material 15 and are joined at side seams 14 formed by weld lines 32.

[0055] The crotch panel 10 comprises an inwardly directed topsheet 16, an outwardly directed backsheet 18 and an absorbent core 20, sandwiched between the topsheet 16 and the backsheet 18.

[0056] Also visible in Fig. 1 are tear lines 8 provided in the chassis 2 and extending between the waist opening 6 and the leg openings 12, as will be further explained below.

[0057] Fig. 2 illustrates the absorbent article 1 of Fig. 1 in opened out state, prior to connection at the side seams 14. A longitudinal central axis X-X extends in alignment with the crotch panel 10 and a transverse central axis Y-Y extends perpendicular to the longitudinal central axis X-X through the crotch.

[0058] As can be seen, the front panel 3 and back panel 4 are both generally rectangular and comprise elastic threads 22 which extend transversally. The tear lines 8 comprise a plurality offused curvilinear line segments 24 that are generally aligned with and extending in the direction of the tear line 8. The line segments 24 are concatenated as a chain to collectively form the tear line 8.

[0059] Figure 2A shows part of the tear line 8 of Figure 2, showing the line segments 24 in greater detail. Each line segment 24 is crescent shaped, with a length Ls of 10 mm and a maximum width Ws of 1 mm. The line segments 24 are arranged to overlap each other in two spaced rows, with a minimum distance Ds between adjacent segments of 2 mm. The resulting overlap is 40%. Each of the elastic threads 22 is thus intersected by at least one of the line segments 24. The overall width of the tear line WTL is 5 mm.

[0060] Figure 3 shows a cross-section through the crotch panel 10 in the direction Ill-Ill of Figure 2. In this view, the absorbent core 20 can be seen sandwiched between the topsheet 16 and the backsheet 18.

[0061] Figure 4 shows a cross-section taken through part of the tear line in Figure 2A in the direction IV- IV. In this view, the chassis material 15 comprises an inner layer 26 and an outer layer 28, with the elastic thread 22 held therebetween fixed by an adhesive applied on the thread at about 0.03 g / m thread. The inner layer 26 and outer layer 28 are both non-woven polyethylene fibre material and completely fuse together under the application of ultrasonic treatment at the line segment 24. A thickness of the line segment is less than 0.4 mm and around 20% of the surrounding chassis material 15. The elastic threads at the line segment may partially lose their elastic properties and become brittle at the location of the line segments and susceptible to rupture or cuts when the tear line is torn.

[0062] Figure 5 shows a number of different tear lines, in which Fig. 5a is a conventional herringbone or tire-tread pattern not falling under the scope of the claims. Fig. 5b is a tear line 8 comprising a continuous line segment 24a with multiple curves and individual line segments 24b each having a single curve. Fig. 5c shows a tear line 8 with crescent shaped line segments 24 similar to those of Figure 2 but with additional segments 30 located to either side of the line segments 24. The additional segments 30 are fused using ultrasound energy in the same manner and to the same degree as the line segments 24. The additional segments are straight lines having a length of 3 mm, aligned in the direction of the tear line. They are located at positions where the line segments 24 do not overlap, in order to ensure that each elastic thread is intercepted at least at two positions.

[0063] Fig. 5d shows a single row of line segments 24, with a single row of additional segments 30. The line segments 24 are crescent shaped and arranged end to end in the direction of the tear line 8. The additional segments 30 are circular and arranged in a wave like pattern, following the line segments 24.

[0064] Fig. 5e shows curvilinear line segments 24, each having two curves in the shape of a sine wave. Each line segment 24 has a length Ls of 30 mm and the line segments mutually overlap by 25%. The width of the tear line WTL is 6 mm.Test Procedure

[0065] The strength of the tear line is tested on a conventional tensile tester (e.g. Lloyd Instruments or Instron Corporation). Testing takes place in a laboratory environment with a temperature of 23°C and a relative humidity of about 50%.

[0066] Samples for testing are punched-out as follows with a punching tool 25 mm wide and 50 mm long. Firstly, the area with the tear line is flattened and straightened (but not stretched). The sample is then punched-out with the length dimension being perpendicular to the tear line (i.e. in the transverse direction of the article. Representative samples are taken from the upper, middle and lower sections of the tear line.

[0067] The tensile tester clamps must be at least as wide as the 25 mm sample width. The vertical distance between the clamps (the gauge length) is set so that the tear line and an additional 5 mm of sample material on each side of the tear line can be accommodated. The tear line should be horizontal and centred between the clamps.

[0068] If slipping occurs (or if handling otherwise can be made easier) tape with a high friction backing can be attached onto the sample end sections. The taped section must then end inside of the clamps, exactly where the test section begins.

[0069] The tensile tester is zeroed, the sample is mounted, and the tensile tester is started. The upper clamp is set to move vertically upwards at a constant speed of 300 mm / min, until the sample breaks apart. The maximum force (in Newtons) encountered during the pull is read. Results are presented in the unit N / 25 mm.Example 1

[0070] A first tested material was a 28 gsm (g / m2) elastic nonwoven material (polypropylene and thermoplastic polyurethane spunbond). The material was provided with tear lines formed as three different ultrasonic patterns with a hand-held ultrasonic horn (Branson LPX Handheld Ultrasonic Welder, 30 kHz, 0.55 kW): 1 . A standard tire pattern according to Fig. 5a; 2. A short, curved pattern according to Fig. 2; and 3. a long continuous curved pattern according to Fig. 5b. The length of the line segments and the width of the whole tear line are as shown in Table 1. The different patterns were made in the same standardised way with a sweeping movement to not break the materials (10 repetitions).

[0071] Table 1 .

[0072] The result is shown in Figure 6A. The long curved continuous ultrasonic pattern required the least force to break requiring 17 N / 25 mm, compared with 32 N / 25 mm for the short curved and 37 N / 25 mm for the tire pattern.

[0073] A further tested material was a threaded nonwoven laminate of two 18 gsm SB / SMS nonwoven sheets with evenly spaced (9 mm) spandex (800 dtex) threads between the sheets. The patterns were patterns 2 and 3 as shown in Table 1 .

[0074] The result is shown in Figure 6B. The long curved continuous ultrasonic pattern required the least force to break requiring 22 N / 25 mm, compared with 35 N / 25 mm for the short-curved pattern.

[0075] The invention has thus been described with reference to the appended figures. It will be understood that the disclosure may be varied within the scope of the appended claims. For example, the shapes and dimensions used for the different line segments forming the tear line may be varied, as indicated above.

Claims

Claims1 . A disposable absorbent article in the form of a pant diaper, comprising a chassis having a front panel and a back panel of chassis material, that meet at the hip to define a waist opening, and a crotch panel extending between the front panel and the back panel to define leg openings, wherein a tear line is provided in the chassis, extending between the waist opening and the leg opening, to facilitate removal of the pant diaper, wherein the tear line comprises a concatenation of fused curvilinear line segments aligned with the tear line.

2. Absorbent article according to claim 1 , wherein the curvilinear line segments have a length of at least 7 mm.

3. Absorbent article according to claim 1 or claim 2, wherein the curvilinear line segments have a maximum width of less than 4 mm.

4. Absorbent article according to any one of the preceding claims, wherein the curvilinear line segments have a length to width ratio of greater than 4.

5. Absorbent article according to any one of the preceding claims, wherein the curvilinear line segments are arranged in overlapping relation.

6. Absorbent article according claim 5, wherein a line segment overlaps an adjacent line segment by at least 10 %.

7. Absorbent article according to any one of the preceding claims, wherein the curvilinear line segments are arranged in a parallel overlapping relation.

8. Absorbent article according to any one of the preceding claims, wherein the curvilinear line segments are distanced from each other by a minimal spacing of at least 1 mm.

9. Absorbent article according to any one of the preceding claims, wherein the tear line comprises between 1 and 100 line segments.

10. Absorbent article according to any one of the preceding claims, wherein the tear line comprises a continuous line segment between the waist opening and the leg opening.11 . Absorbent article according to any one of the preceding claims, wherein the line segments each comprise a single curve.

12. Absorbent article according to any one of the preceding claims, wherein at least some line segments comprise multiple curves.

13. Absorbent article according to any one of the preceding claims, wherein the tear line further comprises additional segments of fused chassis material, located to one or both sides of the line segments.

14. Absorbent article according to any one of the preceding claims, wherein the front panel and the back panel are joined together at a side seam and the tear line is spaced from the side seam on the front panel.

15. Absorbent article according to any one of the preceding claims, wherein the tear line is linear and perpendicular to the waist opening.

16. Absorbent article according to any one of the preceding claims, wherein the start and / or end of the tear line has a line segment with a larger width than the rest of the tear line.

17. Absorbent article according to any of the preceding claims, wherein the tear line intercepts a waist edge and / or a leg edge of the chassis.

18. Absorbent article according to any one of the preceding claims, wherein the tear line has an overall width of between 2 mm and 20 mm.

19. Absorbent article according to any one of the preceding claims, wherein the line segments comprise chassis material that has been fused by ultrasound.

20. Absorbent article according to any one of the preceding claims, wherein the line segments and / or the tear line is non-perforated.

21. Absorbent article according to any one of the preceding claims, wherein the chassis material, at least at the location of the tear line, comprises circumferentially extendable elastic material, such as elastic nonwoven material or a laminate of nonwoven materials and elastic threads.

22. Absorbent article according to any one of the preceding claims, wherein the chassis material, at least at the location of the tear line, comprises fusible polymeric material, such as non-woven fibrous polymeric material.

23. Absorbent article according to claim 21 and claim 22, wherein at each line segment, the polymeric material is fused together around the elastic material.

24. Absorbent article according to any one of the preceding claims, wherein the line segments have a thickness that is less than 30% of the thickness of the adjacent unfused chassis material.

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