WO2011081578A1

WO2011081578A1 - Method for producing an elasticated disposable absorbent article and an elasticated absorbent article

Info

Publication number: WO2011081578A1
Application number: PCT/SE2009/051508
Authority: WO
Inventors: Lucas BÄCK; Ulrica Carlson
Original assignee: Sca Hygiene Products Ab
Priority date: 2009-12-28
Filing date: 2009-12-28
Publication date: 2011-07-07

Abstract

A method for producing an absorbent article comprising an elasticated, contoured base web (27) constituting an outer layer of the absorbent article and being a continuous web to which further components are joined during production of the absorbent article. The method involves bonding an elastic element (12) in a curve shaped pattern (13) between a first continuous web (1) and a covering web (16), cutting the resulting elastic laminate into two parts (17,18) each carrying discrete segments (22,23) of the elastic element (12), transposing the elastic laminate parts (17,18) and rejoining them into a coherent base web (27) having regularly undulating side edges (28,29) and alternating wide parts (30) and narrow parts (31). An assembled base web (27) and an absorbent article (70; 90; 120) are also disclosed.

Description

METHOD FOR PRODUCING AN ELASTICATED DISPOSABLE ABSORBENT ARTICLE AND AN ELASTICATED ABSORBENT ARTICLE

TECHNICAL FIELD

The invention pertains to a method for producing an absorbent article comprising a base web forming a continuous and coherent external layer of the absorbent article and an absorbent article formed according to the method. BACKGROUND ART

A major concern when producing disposable absorbent articles such as diapers, pant diapers absorbent inserts, and the like is to keep the manufacturing costs as low as possible while providing products with high functionality and an appealing finish. To keep costs at a minimum, high production speeds and low material waste are desirable features of the production method.

Over time, disposable diapers and diaper pants have continuously been further developed and are now commonly provided with features such as elastic edges around the legs and waist, elasticated raised barriers, closure systems, multi-component outer covers and core systems with various different materials and layers. Accordingly, disposable absorbent articles of this kind are fairly complicated products and are made up of multiple components that have to be handled and assembled at high speeds in a production process.

Moreover, increasing demands from the users of disposable absorbent articles that the articles closely resemble regular underwear in appearance and comfort have made it necessary for the manufacturers to carefully tailor the articles to optimise fit and comfort. In order to fit snugly around the lower torso, the absorbent articles are provided with leg cut-outs made in the covering material. The cut-out portions are removed and discarded giving rise to a considerable waste of covering materials such as backsheet films and topsheet nonwovens. Such waste is naturally highly undesirable for environmental reasons and as it increases the production cost without contributing anything to the finished absorbent article. The waste is especially large when producing large-size articles such as adult incontinence garments.

Close conformance of the absorbent article to the body of a wearer also requires that the leg openings are elasticated. A particular difficulty is seen in connection with the application of elastic elements along contoured leg openings. The problem of applying elastic elements intermittently and in a nonlinear configuration at the leg edges of an absorbent article has been addressed in US 7,326,31 1 B2 and in WO 98/25767 A1 . The methods disclosed in US 7,326,31 1 B2 and WO 98/25767 A1 involve making an elastic laminate by attaching a continuous elastic element in a curved pattern on a supporting web and dividing the supporting web in two halves each carrying discrete portions of the elastic element. The two parts of the supporting web are then attached along the side edges of a production web with the elastic portions forming leg elastic in the finished product.

Although allowing leg elastic to be incorporated in an absorbent article in a fairly simple manner, the methods in US 7,326,31 1 B2 and WO 98/25767 A1 both require additional material for carrying the elastic element to be introduced in the manufacturing process. As the supporting webs have no function in the finished product but is merely a means for handling the elastic elements in the process, the supporting webs add unwanted costs to the absorbent article and is also negative for environmental reasons. When making disposable absorbent articles, the manufacturers are highly concerned to keep the use of raw materials to a minimum in order to reduce the carbon footprint of the disposable absorbent article. Moreover, neither method solves the problem of minimising waste when forming leg cut-outs in a manufacturing web. One objective of the present invention is therefore to offer a simplified and more efficient manufacturing method for the production of disposable absorbent articles. A further object of the invention is to reduce or eliminate waste of covering materials when producing disposable absorbent articles. A further objective is to provide a low-cost yet highly functional and aesthetically pleasing disposable absorbent article.

SUMMARY OF THE INVENTION

In accordance with the invention, there is provided a method for producing an absorbent article comprising a base web forming a continuous and coherent external layer of the absorbent article. The method includes the steps of:

• feeding a first continuous web along a production path in a machine direction, MD, the web having a longitudinal centre line in the machine direction, MD,

• applying an adhesive coating to a predetermined portion of the first continuous web

• feeding a first continuous elastic element in the machine direction, MD, along a wave-shaped curve, the waves having equal wave length, t, and equal amplitude, A, each wave having a crest comprising a wave crest segment having a length of from 10% to 40% of the wave length, t, preferably a length of from 20% to 30% of the wave length, t, and a trough comprising a wave trough segment having a length equal to that of the wave crest segment, and having intermediate wave segments connecting the wave crest segments and the wave trough segments, the intermediate wave segments having a leading side in the machine direction, MD, and a trailing side in the machine direction, MD, attaching the first continuous elastic element to the adhesive coating on the first continuous web along the wave-shaped curve of the first continuous elastic element,

forming an elasticated laminate having first and second longitudinal edges running parallel to the machine direction, MD, by applying a continuous covering web to the first continuous web to cover the continuous elastic element and the adhesive coating,

cutting the elasticated laminate into first and second laminate parts along a cutting line following the wave-shaped curve of the first continuous elastic element, the cutting line being arranged at a distance of not more than 70 mm from the first continuous elastic element and being arranged always on the same one of the leading side of each intermediate wave segment or the trailing side of each intermediate wave segment of the elastic wave-shaped curve and crossing the first elastic element always only at the same one of the leading end of each wave crest segment of the elastic wave-shaped curve and the leading end of each wave trough segment; or crossing the first elastic element always only at the same one of the trailing end of each wave crest segment of the elastic wave-shaped curve and the trailing end of each wave trough segment,

separating the first and second laminate parts along the cutting line,

moving the first and/or second laminate parts in the cross machine direction, CD, perpendicular to the machine direction, MD, bringing the first and second longitudinal edges of the elastic laminate together, and shifting the first and second laminate parts relative to one another in the machine direction, MD, by an odd multiple of half a wavelength, t,

bonding the first and second laminate parts to each other along the longitudinal edges of the elastic laminate to form a continuous coherent base web having regularly alternating wide portions and narrow portions,

• intermittently applying absorbent cores to the base web at each narrow portion,

· forming individual absorbent articles by severing the base web and any component overlapping with the base web in the cross machine direction, CD, between the absorbent cores at the wide portions of the base web.

In accordance with the method of the invention, a continuous base web can be formed without any waste of covering material. A "base web" as defined herein is a continuous web used in the production of an absorbent article and that will form an outer layer in the finished article. The base web serves as a support or carrier web in the manufacturing of the absorbent article such that all other components of the absorbent article are laid down onto and/or joined with the base web. Depending on whether the base web is a liquid permeable material or a liquid impermeable material, it will form the topsheet or the backsheet in the finished absorbent article. The base web will also form any side portions of the absorbent article located outside of the absorbent core, such as flexible side flaps along the leg openings and side panels located between the leg openings and the waist opening in a disposable absorbent garment. After application of the elastic elements, cutting the base web in two parts and reassembling the base web parts along the non-cut edges, the resulting contoured web will have intermittent elastication along its curved outer edges and a continuous seam in the longitudinal direction of the web. The base web may consist of or comprise a single layer of material or may consist of or comprise a laminate of two or more layers. The base web may be a compound web having different materials within different areas of the web. By way of example, a portion of the base web forming side panels in the finished absorbent article can be different from the portion of the base web arranged over the absorbent core. Accordingly, combinations of materials differing in number of layers, composition, permeability, colour, etc. may be used. The base web may comprise a single layer web that has been laminated to one or more webs over only one or more portions of the single layer web. Alternatively, webs having different properties may be joined in a side-by-side arrangement.

The adhesive coating is applied to the first continuous web at least in the area of the first continuous web where the first continuous elastic element is attached. Accordingly, the adhesive coating may be applied in a wave shaped pattern having the same wave length and curvature as the wave- shaped curve of the first continuous elastic element. Alternatively, the adhesive coating may be applied as a band-shaped coating extending parallel with the machine direction, MD and having a width in the cross machine direction, CD being greater than two times the amplitude, A, of the wave-shaped curve of the first elastic element or having the same width as the continuous covering web. The adhesive coating may be made to coincide fully with the elastic wave-shaped curve so that no parts of the first elastic element extend outside of the adhesive coating pattern and so that the first elastic element is attached along its full length to the first continuous web. Alternatively, parts of the elastic element in the vicinity of the cuts, may be unattached to the first continuous web so that these parts may snap back and reduce the length of the elastic segment left in the finished absorbent article. In accordance with the invention, when dividing the elasticated laminate comprising the first continuous web, the elastic element and the continuous covering web, the cutting line will always be arranged on the inside of the linear wave crest and wave trough segments as seen from the first and second longitudinal edges of the first continuous web. The cutting line will always cut the elastic element at the same end of each of the wave crest and wave trough segment, which may be the leading end or the trailing end depending on the travelling direction of the first continuous web. When using a single continuous elastic element applied along a sinusoidal curve having wave crests and wave troughs, the resulting absorbent article will have elastication along the leg openings only in the crotch portion and along one of the front and rear leg edges of the article. Preferably, the elastication will be arranged at the rear leg edge where the elastic element will bring the leg opening to conform to the curvature of a wearer's buttocks. The front leg edge will remain smooth and non-wrinkled by elastic contraction which may be an advantage when wishing to conceal the absorbent article beneath tight-fitting clothes.

The elastic curve may have a curvature over the full length of any or all of the wave crest segments, wave trough segments and intermediate segments such that no completely linear parts are found on the elastic curve. However, any segment of the elastic curve may be linear or straight as desired.

In the method according to the invention, the wave crest segments and the wave trough segments may extend linearly along a portion of their length such as over at least 60% of their length or along at least 75% of their length, the linear part of each wave crest segment and each wave trough segment being arranged parallel to the first and second longitudinal edges of the first continuous web. The total length of the wave crest segments and the wave trough segments is determined as the length of the elastic element from the point at each wave crest and wave trough where the elastic element is cut to the corresponding point on the respective wave crest and wave trough opposite the cut.

The wave-length of the first elastic wave-shaped curve and of the cutting line corresponds to the length of a single disposable absorbent article.

The linear parts of the wave crest segments will form linear edge sections at the crotch portion of the finished disposable absorbent article and also at the parts of the front and rear portions of the absorbent article that will be placed over the hips of the wearer when the article is worn. Particularly at the front and rear portions of the article, it may be desirable that the edge sections are generally straight or linear over at least a portion of the edge section. Straight edge sections at the hip portions of the absorbent article may make it easier to apply fastening elements for fastening the absorbent article around the waist of a wearer. Straight edge sections also allows fastening together of the front and rear portions of the diaper to be made over a longer part of the side edge. When manufacturing disposable absorbent pants having conventional side seams it is necessary that the side edges have straight edges allowing side joins to be formed between the front and rear portions of the absorbent pants.

However, the invention is not limited to embodiments where the elastic curve has straight portions. Accordingly, the elastic curve may have a curvature over the full length of the wave crest segments and the wave trough segments if desired. In practice, the elastic curve will always have at least slightly rounded corner at the ends of linear portions where the curve changes direction. The cutting line can be made to follow a rounded shape of the elastic curve or may be composed by more distinctly linear segments.

In accordance with the method of the invention, the intermediate wave segments may have a curved appearance or may extend linearly along a portion of their length such as over at least 60% of their length. The length of an intermediate wave segment is defined as the length of the elastic element between the wave crest segments and the wave trough segments and is ultimately determined by how far inside of the elastic element the elastic curve is cut as the lateral position of the cutting line at the wave crests and the wave troughs determines the length of the wave crest segments and the wave trough segments. Furthermore, the intermediate wave segments extend linearly along at least 75% of their length. The intermediate wave segments form front and rear portions of the leg edges in the finished absorbent article. The first continuous web may comprise a liquid permeable web such as a nonwoven web, or a perforated plastic web or net. The liquid permeable web may then form a liquid permeable topsheet on the finished absorbent article and may also form breathable sideflaps and breathable side panels. Alternatively, the liquid permeable web may be an outer layer of an at least partially liquid impermeable backsheet structure in the finished absorbent article. If the liquid permeable web is a nonwoven material, the liquid permeable web may provide a textile feel to the outer surface of the backsheet and may extend into side flaps and side panels to contribute to breathability and a body-contacting surface having a textile feel. A perforated plastic web or a net material would also provide breathability, but would not have the textile characteristics of a nonwoven material.

In accordance with the invention, the covering web may be a liquid permeable web. In addition to serving as a locking means for the elastic element so that the elastic element is firmly held in the intended curve pattern between the first continuous web and the covering web, the covering web may be a secondary topsheet material in the finished absorbent article. Such secondary topsheet materials are well known in the art and are usually arranged to promote or control liquid distribution in the absorbent article.

In a preferred embodiment of the invention, both the first continuous web and the cover web are liquid permeable, making the assembled base web liquid permeable. The liquid permeable base web will form breathable side panels and a liquid permeable topsheet in the finished absorbent article. In accordance with the invention, both the first continuous web and the covering web may be liquid permeable webs and the absorbent core may be covered by a liquid impermeable layer. The liquid impermeable layer may be a continuous liquid impermeable web that is applied over the absorbent core as the base web moves along the production path. Alternatively, the liquid impermeable layer may be in the form of discontinuous pieces of material that are applied to the absorbent cores. A further alternative is to apply the liquid impermeable layer in a separate process, before joining the absorbent cores with the moving base web.

Suitable liquid impermeable materials are those commonly used in the art such as breathable and non-breathable plastic films, hydrophobic nonwovens and liquid impermeable laminates.

The continuous covering web may comprise an integral edge portion of the first continuous web that is folded in over the first continuous web and the first elastic element. The covering web may be formed from one or both edge portions of the first continuous web and may constitute all or part of the covering web. In this embodiment, the fold between the first continuous web and the covering web will form at least one of the first and second longitudinal edges of the first continuous web. Alternatively to the covering web being an integral portion of the first continuous web, the covering web may be a continuous web that is separate from the first continuous web. Hybrid embodiments wherein the covering web comprises both a continuous web that is separate from the first continuous web and a web portion that is integral with the first continuous web are also conceivable within the scope of the invention. The wave-shaped curve of the first elastic element may be centred about the longitudinal centre line on the first continuous web. By arranging the elastic element centrally on the first continuous web, the bond between the reassembled parts of the divided elasticated laminate will form a centrally arranged longitudinal seam extending along the longitudinal centreline in the finished absorbent article. This embodiment may be preferred in instances where a positioning means is desired, as the seam may be used as an indication that the absorbent article is symmetrically placed in relation to the body of the user. The seam may include colouration to aid in visual detection.

Alternatively, the wave-shaped curve of the first elastic element may be offset towards a side edge of the first continuous web. In this embodiment, the seam between the two reassembled parts of the divided elasticated laminate will be offset to one longitudinal side of the finished absorbent article. This embodiment may be preferred in some instances as when it is desired to have a smooth central area on the covering of the absorbent article. In addition, with an offset seam, the seam may be concealed beneath a barrier structure arranged along a side edge of the absorbent article. According to the method of the invention, the first elastic element may be applied to the first continuous web while held in a tensioned state. Other options are to use an elastic element that is activated by means of heat, stretching, irradiation or chemically after attachment to the first continuous web.

The method for producing an absorbent article according to the invention may comprise the steps of:

• feeding a second continuous elastic element in the machine direction, MD along a second wave-shaped curve having the same wave length as the first wave-shaped curve of the first elastic element, the second wave-shaped curve having wave crest segments and wave trough segments and intermediate wave segments between the wave crest segments and the wave trough segments corresponding to the wave crest segments and wave trough segments and intermediate wave segments of the first wave-shaped curve of the first elastic element the second wave-shaped curve of the second elastic element being spaced in the machine direction, MD, by a distance, d, of 10-70 mm from the first elastic element along the intermediate wave segments of the first elastic element,

• attaching the second continuous elastic element to the adhesive coating on the first continuous web,

• forming an elasticated laminate by applying the continuous covering web to the first continuous web to cover the first elastic element and the second elastic element and the adhesive coating

· cutting the elasticated laminate into first and second laminate parts along a cutting line following the wave-shaped curves of the first continuous elastic element and the second continuous elastic element, the cutting line being arranged between the first continuous elastic element and the second continuous elastic element along the intermediate wave segments of the first continuous elastic element and the second continuous elastic element and always crossing the second continuous elastic element only at the other of the leading end and the trailing end of each wave crest segment of the second elastic wave-shaped curve and always only at the other of the leading end or the trailing end of each wave trough segment of the second elastic wave shaped curve as compared to the first elastic wave shaped curve. When two elastic elements are being applied to the first continuous web, the adhesive coating is applied to the first continuous web in a pattern that will accommodate both elastic elements. The adhesive coating may be applied in a wave shaped pattern coinciding with the wave-shaped curves of the first and second continuous elastic elements. Alternatively, the adhesive coating may be applied as a band-shaped coating extending parallel with the machine direction, MD and having a width in the cross machine direction, CD being greater than two times the amplitude, A, of the elastic wave-shaped curve having the greatest amplitude or having the same width as the continuous covering web. The adhesive coating may be made to coincide fully with the elastic wave-shaped curves so that no parts of the first or second elastic elements extend outside of the adhesive coating pattern and so that the first and second elastic elements are attached along their full length to the first continuous web. Alternatively, parts of the elastic elements in the vicinity of the cuts, may be unattached to the first continuous web so that these parts may snap back and reduce the length of the corresponding elastic segment left in the finished absorbent article.

The cutting line is arranged to cut the second continuous elastic element at the wave crests and wave troughs on the opposite to the cuts in the first continuous elastic elements. Accordingly, if the first elastic element is cut at the leading end of each wave crest and wave trough segment, the second elastic element will be cut at the trailing end of each wave crest and wave trough segment, and vice versa.

When the method includes the application of a second continuous elastic element arranged in a sinusoidal curve pattern that is slightly offset in the machine direction from the first continuous elastic element, the resulting absorbent article will have elastication along the full length of the leg edges. Accordingly, the absorbent article will have fully elasticated leg openings.

As with the first continuous elastic element, the second continuous elastic element may be attached while held in a tensioned state, or may be subsequently activated by means of heat, irradiation, stretching or by chemical agents. If the base web is arranged to form a backsheet or outer backing layer on the finished absorbent article, the method may comprise attaching a liquid permeable cover layer over the absorbent core. This method step is optional and may be omitted, for instance if the core is part of a prefabricated core component that has already been provided with a liquid permeable cover layer or if the core has sufficient integrity to make a separate cover unnecessary. Further, if the base web is a liquid permeable material, the absorbent cores may be provided with a liquid impermeable barrier sheet on the surface thereof facing the base web, before joining the cores to the base web.

The method according to the invention may include further steps to incorporate additional components such as a transfer layer, waist elastic, elasticated barriers, fasteners, belts, wetness indicators, lotion, etc. as is well known in the art.

The method according to the invention may further comprise forming elasticated barriers extending in the machine direction, MD on each side of the first elastic wave shaped curve before cutting the elastic laminate into two parts the cutting line being arranged laterally completely inside of the elasticated barriers, between the elasticated barriers and the first continuous elastic element. If a second continuous elastic element is present, the cutting line will also be located between the second continuous elastic element and the elasticated barriers, so that the elasticated barriers are left intact when cutting the elastic laminate into two parts.

A continuous base web according to the invention for use as a coherent surface layer such as a topsheet structure or a backsheet structure in a disposable absorbent article has a longitudinal direction with a longitudinal centre line and side edges extending in the longitudinal direction. The base web consists of two parts that are joined together in a seam extending in the longitudinal direction and comprises a first continuous web and a continuous covering web laminated with the first continuous web. The side edges of the base web are wave shaped, the waves being of equal length and amplitude and being synchronized so that the base web has regularly alternating wide portions constituting front and back body portions and narrow portions constituting crotch portions in the base web and comprising elastic elements arranged along the side edges of the base web in discrete segments with one segment extending along each side edge in each crotch portion and into one of the front or back body portions.

The continuous base web according to the invention may comprise second elastic elements arranged along the side edges of the base web as second discrete segments with one segment extending along each side edge in each crotch portion and into the other of the front or back body portions with the first and second discrete elastic segments extending parallel to each other in each crotch portions. As each elastic element may comprise one or more elastic part elements, such as in multi-string elastic elements, the implication of the presence of two elastic elements in the crotch portion but not in the front and back body portions is that the number of elastic threads, strings, or bands in the crotch portion is the sum of the number of elastic threads, strings or bands in each of the two elastic elements. If the first and the second elastic elements are identical in their construction, there will be twice as many elastic threads, strings, or bands in the crotch portions as in the front and rear body portions.

A disposable absorbent article according to the invention has a longitudinal direction and a transverse direction, side edges extending in the longitudinal direction and waist edges extending in the transverse direction, a front body portion, a rear body portion and a crotch portion between the front body portion and the rear body portion and comprises a liquid permeable topsheet structure and a liquid impermeable backsheet structure and an absorbent core enclosed between the topsheet structure and the backsheet structure. The absorbent article has first elastic elements arranged as continuous elastic segments along the side edges at the crotch portion and along the side edges of one of the front or rear body portions, each elastic element having a linear segment in the crotch portion.

The absorbent article according to the invention may comprise second elastic elements that are arranged as continuous elastic segments along the side edges at the crotch portion and along the side edges of the other of the front or rear body portions, so that the absorbent article has dual, parallel elastic elements in the crotch portion and single elastic elements in the front and rear body portions.

In this embodiment, the absorbent article has elastic elements completely encircling the leg openings, the first and second elastic elements being arranged parallel to each other in the crotch portion of the absorbent article.

The topsheet structure of the absorbent article according to the invention may be a base web as disclosed herein. Alternatively, the backsheet structure may be a base web as disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will in the following be described in greater detail with reference to the appended schematic drawings, wherein

Fig. 1 shows the production of an elasticated laminate according to the invention;

Fig. 2 shows the division of the elasticated laminate of Fig. 1 into two parts; shows the two laminate parts in Fig. 2 after having been shifted transversely; shows the two laminate parts in Fig. 3 after having been shifted longitudinally and brought together to form a base web according to the invention; shows the incorporation of absorbent cores with the base web; shows the incorporation of further components with the base web; shows the finished absorbent article of Figs. 1 -6; shows the production of an elasticated laminate having two elastic elements; shows an absorbent article incorporating a base web made from the elasticated laminate in Fig. 8; shows the production of an elasticated laminate having an asymmetrically arranged elastic element; shows a base web made from the elasticated laminate in Fig. 10; shows an absorbent article incorporating the base web in Fig. 10; shows an elasticated laminate with a cover web being an integral part of the continuous web;

Fig. 14 shows an elasticated laminate comprising raised elastic barriers; Fig. 15 shows a further example of an elasticated laminate comprising raised elastic barriers;

Fig. 16 shows a diaper incorporating the elasticated laminate of Fig.

15; Fig. 17 is a diagram showing different curve shapes; and

Figs. 18a-18d show product contours resulting from the curve shapes of

Fig. 17.

DETAILED DESCRIPTION

The method for producing an absorbent article in accordance with the invention will be described mainly with reference to the production of a diaper having fastening elements for fastening together the diaper around the lower trunk of a wearer. However, it is to be understood, that the method may equally well be adapted to the production of absorbent pants, such as pant diapers and sanitary pants for menstruation and incontinence. The absorbent articles are of the garment type and are worn as a pair of underpants around the wearer's lower trunk. The absorbent articles according to the invention are not restricted to any particular size or category of user but may be shaped and sized to fit infants, larger children or adults.

Fig. 1 shows a first continuous web 1 being advanced in a machine direction, MD and having a width extension in a cross machine direction, CD.

The first continuous web 1 has first and second longitudinal edges 2, 3 parallel to the MD and a longitudinal centre line 4 in the MD. The first continuous web may be any kind of material that is suitable for use as an outer cover layer of a disposable absorbent article, such as nonwoven materials, perforated and non-perforated plastic films, netting, and laminates and combinations of such materials. The plastic films may be breathable or non-breathable as desired. An adhesive coating 5 is applied to the first continuous web 1 in a wave pattern 6.

The adhesive is preferably a thermoplastic polymer adhesive, commonly known as "hot melt adhesive". The coating may be applied by any suitable technique as known in the art such as spraying, meltblowing, slot-coating, etc.

A first continuous elastic element 12 is fed in the machine direction, MD along a wave-shaped curve 13 coinciding with the first wave pattern 6 of the adhesive coating 5

The waves of the elastic curve have equal wave length, t, and equal amplitude, A, each wave having a wave crest 7 comprising a wave crest segment 8 having a length of from 10% to 40% of the wave length, t, preferably a length of from 20% to 30% of the wave length, t, and a wave trough 9 comprising a wave trough segment 10 having a length of from 10% to 40% of the wave length, I, preferably a length of from 20% to 30% of the wave length, t, and having intermediate wave segments 1 1 connecting the wave crest segments 8 and the wave trough segments 10.

The elastic element may be in the form of one or more elastic threads, bands or strings. All commonly used elastic materials such as natural or synthetic rubber elastic foam, etc. can be employed. The first continuous elastic element 12 is brought into contact with the adhesive coating 5 on the first continuous web 1 , preferably while held in a stretched state so that the elastic element 12 is adhered to the first continuous web 1 in a tensioned state. This will cause the elastic element to contract and form an elastic gather once the finished diaper is severed from the continuous web and the tension in the elastic element is released. Alternatively, as herein disclosed, the elastic element may be applied in a non-tensioned state and may be activated at a later stage by treatment by means of heat, irradiation, chemicals or by mechanical treatment.

The next production step shown in Fig. 1 is the application of a covering web 16 on top of the first continuous web 1 and the elastic element 12. The covering web is brought into contact with the adhesive coating 5 and may be made to adhere to the adhesive coating 5 by pressing together the covering web 16 and the first continuous web. The two webs 1 , 16 may additionally or alternatively be joined by means of a thin coating of adhesive applied between the webs 1 , 16 or by ultrasonical or heat bonding of the webs. Ultrasonical bonding and heat bonding require at least one of the webs to comprise thermoplastic material such as polyolefins, polyester, etc. in an amount sufficient to accomplish the bonding. As shown in Fig. 1 , the covering web may have a width in the cross machine direction, CD; that is just sufficient to cover the adhesive coating 5. Alternatively, the covering web 16 may have the same width as the first continuous web 1 or even a larger width so that it extends laterally beyond the first continuous web 1 at one or both longitudinal edges 2, 3 of the elastic laminate.

The covering web 16 may be chosen among nonwoven materials, perforated and non-perforated plastic films, netting, and laminates and combinations of such materials. The plastic films may be breathable or non-breathable but are preferably breathable. In the finished disposable absorbent article, the covering web 16 will be applied along the longitudinal side edges of the article and will extend into the article's side panels in the portions of the article that will cover a wearer's hips and into the flexible elasticated side flaps that are fornned along the article's leg edges. These parts of a diaper or other disposable absorbent garment will generally be located laterally outside of the absorbent core and will be in close body-contact while the garment is being worn.

In the finished disposable absorbent article, the covering web 16 will be on the outside garment-facing side of the article or on the inside body-facing side of the article, depending on whether the elasticated laminate forms a body-facing cover layer or a garment facing cover layer.

By bonding together the first continuous web 1 with the covering web 16, an elasticated laminate is formed with the elastic element sandwiched between the first continuous web 1 and the covering web 16.

After application of the covering web 16 over the first continuous web 1 and the curve 13 of the elastic element 12, the resulting elasticated laminate is cut into first and second laminate parts 17, 18 along a cutting line 19 following the wave-shaped curve 13 of the first continuous elastic element 12. The cutting line 19 is arranged at a distance of not more than 50 mm from the first elastic element and is arranged on the leading side 14 of each intermediate wave segment 1 1 of the elastic wave-shaped curve 13 and crossing the first elastic element 12 only at the leading end 20 of each wave crest segment 8 of the elastic wave-shaped curve 13 and at the leading end 21 of each wave trough segment 10. Alternatively, the cutting may be arranged to be arranged on the trailing side 15 of each intermediate wave segment 1 1 of the elastic wave-shaped curve 13 and to cross the first elastic element 12 only at the trailing end 20 of each wave crest segment 8 of the elastic wave-shaped curve 13 and at the trailing end 21 of each wave trough segment 10 As seen in Fig. 1 , when dividing the elasticated laminate comprising the first continuous web 1 , the continuous elastic element 12 and the continuous covering web 16 into two parts 17,18, the cutting line 19 will always be arranged on the inside of the linear wave crest and wave trough segments 8,10 as seen from the first and second longitudinal edges 2,3 of the first continuous web 1 .

The length of the wave crest segments 8 and the wave trough segments 10 of the continuous elastic element 21 is defined as shown in Fig. 1 to be the length of the elastic element from the point at each wave crest 7 and wave trough 9 where the elastic element is subsequently cut to the corresponding point on the respective wave crest 7 and wave trough 9 opposite the cut. The length of the intermediate wave segments 1 1 is defined as the length of the elastic element 12 between a wave crest segment 8 and a wave trough segment 10. The intermediate segments of the elastic element 12 have a leading side 14 in the machine direction and a trailing side 15 in the machine direction.

For economical reasons it is generally preferred that the adhesive coating 5 follows the curve of the elastic element 12. However, it is not a necessary feature of the invention that the adhesive coating is applied in a curve pattern. Accordingly, a continuous band shaped coating may be applied covering the area between the maxima and minima of the elastic curve thereby avoiding the need of synchronising the adhesive coating with the wave-shaped curve 13 of the elastic element. It is generally desirable that the elastic element 12 is attached to the first continuous web 1 along its full length. However, if elastification of a shorter part of the resulting absorbent article is desired a portion of the elastic element may be left unattached in the vicinity of the cut in the elastic laminate web.

As shown in Fig. 2, the first and second laminate parts 17,18 are subsequently moved apart in the cross machine direction, CD so that the parts 17, 18 are separated along the cutting line 19. As is illustrated by Fig. 2, the cutting line 19 cuts the continuous elastic element 12 into discrete elastic segments 22, 23. In Fig. 3, the first and second laminate parts 17, 18 have been moved in the cross machine direction, CD to bring the first and second longitudinal edges 2, 3 of the first continuous web 1 together.

In Fig. 4, the first and second laminate parts 17, 18 have been further shifted relative to one another in the machine direction, MD by an odd multiple of half a wavelength, t, synchronising the maxima and minima 24, 25 of each laminate part 17, 18 with each other, as shown in Fig. 4. In addition, the first and second laminate parts 17, 18 have been bonded to each other along the longitudinal edges 2,3 of the original continuous web 1 in a central seam 26 to form a coherent base web 27. The assembled base web 27 has undulating side edges 28, 29 and a planar shape with regularly alternating wide portions 30 intended to form front and back body portions in the finished diaper and narrow portions 31 intended to form crotch portions in the finished absorbent article. The base web 27 has elastic elements arranged along the side edges 28, 29of the base web 27 in discrete segments 22, 23 with one segment 22,23 extending along each side edge 28, 29 in each narrow portion 31 and into the wide portion 30 located at the leading end 32 of the narrow portion 31 . Although shown as separate steps, the transposition of the first and second laminate parts 17, 18 may be carried out simultaneously or in the reverse order so that the MD shifting takes place before the CD shifting.

Fig. 5 shows the base web 27 onto which absorbent cores 33 have been laid down. The absorbent cores 33 are laid down intermittently on the base web 27 with one absorbent core 33 placed at each narrow portion 31 of the base web 27. The absorbent cores 33 are shown as rectangular structures. However, it should be understood that the shape of the absorbent cores are not limiting to the invention. The absorbent core could have any suitable shape such as hourglass shape , T-shape l-shape or similar. The size of the absorbent cores could be smaller or larger than that shown. The absorbent cores may be of any suitable composition and may comprise layers of different materials, different sizes, shapes, etc. as desired. The materials for use in the absorbent cores are those commonly used in the art such as absorbent nonwoven webs, absorbent fluff structures, tissue and superabsorbent hydrogelling materials such as superabsorbent particles, granules, fibres, flakes and foams. The absorbent materials may be natural fibres, such as cellulose fluff pulp, hemp, flax, cotton, etc. or may be man- made such as viscose and polymeric absorbent materials including superabsorbent polyacrylates and starch-based superabsorbents. The absorption core 33 may also comprise nonabsorbent components such as stiffening elements, shaping elements, binders, etc. Various types of liquid- receiving porous structures such as fibre wads, open-cell foam or the like can also be included in the core.

The absorbent cores 33 are subsequently covered by a second continuous web 34. If the first continuous web 1 and preferably also the covering web 16 have been chosen to be liquid permeable webs forming a liquid permeable outer cover layer in the finished disposable absorbent article, the second continuous web 34 is preferably a liquid impermeable barrier layer. As shown in Figs. 5 and 6, the second continuous web 34 needs only have a width in the cross machine direction, CD, corresponding to the width of the absorbent core 33. When using larger cores than those shown in Figs. 5 and 6, it may even be sufficient if the barrier web in the cross machine direction, CD, covers only that portion of each core that during use of the absorbent article is expected to receive and absorb a major part of body exudates reaching the absorbent article. The liquid-impervious barrier web may comprise any suitable liquid- impermeable material as known in the art, such as plastic film, a nonwoven sheet which has been coated with a liquid barrier material, or some other flexible material sheet which has the ability to withstand liquid penetration. However, it is usually preferred that the liquid-impervious barrier material is a breathable material that permits the passage of air and water vapour through the material in order to avoid clamminess and skin irritation when wearing the absorbent article. If the first continuous web 1 was chosen to be a liquid impermeable web forming a liquid impermeable outer cover layer in the finished disposable absorbent article, the second continuous web 34 will be a liquid permeable layer that will be a topsheet layer in the finished absorbent article. A liquid-permeable topsheet web may be formed from any material or material combination known for the purpose, such as nonwoven material, perforated plastic film, net material, tow, or the like. The topsheet layer may comprise or consist of a laminate of two or more sheets of the same or different material.

As shown in Fig. 6 the base web 27 is provided with fastener tapes 35, for fastening the finished diaper around the waist of a wearer. Fig. 6 shows dual fastening tapes being intermittently attached along the undulating side edges 28, 29 in the trailing half of each wide portion 30 of the base web 27. Although the fastener tapes 35 are shown as dual fasteners, it should be understood that single fasteners could be used as well as multiple fasteners. The fastener tapes 35 may be adhesive fasteners of hook-fasteners, as is well-known in the art. Other types of fasteners are also contemplated within the scope of the invention, such as hook-and-eye fasteners, press-studs, buttons, belts, etc. The fasteners are optional and may be omitted for instance in pant-diapers, and absorbent inserts. In order to simplify the principles of the invention, only a few typical diaper components have been shown to be joined to the base web 27. However, it is to be understood that any other conventional component could be added to the base web 27 as desired. Accordingly, the base web may be provided with multilayered absorbent cores, waist elastic elements, elasticated and/or non- elasticated raised barrier structures, belts, liquid indicators, lotion, odour control agents, liquid handling layers, etc. A liquid handling layer may be an acquisition layer, a transfer layer or similar. Such materials are typically lofty nonwoven webs or embossed nonwoven webs although perforated films and nettings are sometimes used for this purpose. A liquid-handling layer is commonly placed between the absorbent core and an outer liquid-permeable topsheet layer.

All components may be joined to the base web 27 directly or indirectly by being bonded to the base web 27 or another component or by being held in place by being sandwiched between other components. Bonding may be effected by any method known in the art such as by means of adhesive, by heat bonding or embossing or by ultrasonical bonding. When all desired components have been joined to the base web 27, individual absorbent articles are formed by severing the base web 27 and any other overlapping component such as the second continuous web 34 in the cross machine direction, CD, between the absorbent cores 33 at the wide portions 30 of the base web 27.

Fig. 7 shows a diaper 70 that has been produced in accordance with the method in Figs. 1 -6. The diaper in Fig. 7 is shown in a flat-out state from the garment-facing side and has a generally hour-glass shape. The diaper 70 has a narrow crotch portion 71 and wider front and rear portions 72, 73, generally longitudinally extending side edges 74,75 and transversely extending front and rear waist edges 76,77. When the diaper is being worn, the side edges 74, 75 will form leg cuffs, encircling the wearer's legs and the front and rear waist edges 76,77 will encircle the wearer's waist and form a waist opening. The inner body-facing surface of the diaper is constituted by a liquid- permeable base web 27 which forms front and rear side panels 78,79 and a liquid permeable topsheet 80. The seam 26 that was formed when reassembling the two parts of the elasticated laminate in Fig. 2 is visible on the topsheet 80 along the longitudinal centre line 4 of the diaper. The seam may be coloured or printed with a visually detectable pattern to aid in positioning the diaper 70 correctly on a wearer.

A liquid impermeable backsheet 81 extends the full length of the diaper 70 and is slightly wider than the rectangular absorbent core 33.

By dividing the elastic laminate shown in Fig. 1 into two parts, as shown in Fig. 2, the continuous elastic element 12 in Fig. 1 was simultaneously cut into discrete elastic segments 22, 23 forming leg elastic in the diaper 70 shown in Fig. 7. The leg elastic resulting from the Fig. 1 -6 process extends only along the inclined portions 82,83 of the side edges 74,75 on the rear portion 73, and along the side edges 74,75 the full length of the crotch portion 71 but not along the inclined portions 84,85 of the side edges 74,75 on the front portion 72. This means that only the rear and crotch parts of the leg cuffs are elasticated.

Fig. 8 shows the production of an elasticated laminate web comprising two elastic elements 12a, 12b. The elasticated laminate web in Fig. 8 differs from that shown in Fig. 1 only in that two elastic elements 12a, 12b are applied between the first continuous web 1 and the continuous covering web 16.

As in the process in Fig. 1 , an adhesive coating 5 is applied to the first continuous web 1 in a wave pattern 6. However, as described in connection with Fig. 1 , the adhesive coating does not need to be in a wave pattern but can be applied as a continuous band-shaped coating or an interrupted coating, as desired as long the elastic elements 12a, 12b can be attached to the first continuous web 1 along desired parts of the elastic elements12a,12b.

While the adhesive coating 5 is shown in Fig. 8 as a single band-shaped coating, the adhesive coating 5 in Fig. 8 could alternatively be in the form of first and second band-shaped adhesive coatings corresponding to the first and second elastic elements 12a, 12b.

A first continuous elastic element 12a is fed in the machine direction, MD along a first wave-shaped curve 13a coinciding with the wave pattern 6 of the adhesive coating 5. The waves of the first wave shaped curve 13a have equal wave length, t, and equal amplitude, A, each wave having a wave crest 7a comprising a wave crest segment 8a having a length of from 10% to 40% of the wave length, t, preferably a length of from 20% to 30% of the wave length, t, and a wave trough 9a comprising a wave trough segment 10a having a length of from 10% to 40% of the wave length, t, preferably a length of from 20% to 30% of the wave length, t, and having intermediate wave segments 1 1 a connecting the wave crest segments 8a and the wave trough segments 10a.

A second continuous elastic element 12b is simultaneously fed in the machine direction, MD along a wave-shaped curve 13b also coinciding with the first wave pattern 6 of the adhesive coating 5 and having corresponding wave crest segments 7b and wave trough segments 9b and intermediate wave segments 1 1 b between the wave crest segments 7b and wave trough segments 9b, as the first continuous elastic element 12a. The second elastic element 12b is spaced in the machine direction, MD by a distance d of 10-70 mm from the first elastic element along the intermediate wave segments 1 1 a, 1 1 b of the first and second elastic elements 12a, 12b. The elastic elements 12a, 12b have a leading side 14a, 14b in the machine direction, MD and a trailing side 15a, 15b in the machine direction, MD. The first and second continuous elastic elements 12a, 12b are brought into contact with the adhesive coating 5 on the first continuous web 1 , preferably while held in a stretched state so that the elastic elements 12a, 12b are adhered to the first continuous web 1 in a tensioned state. If the adhesive coating 5 comprises first and second adhesive coatings applied along first and second wave patterns, the first and second elastic elements 12a, 12b are adhered to the first and second adhesive coatings, respectively.

The continuous covering web 16 is then applied to the first continuous web to cover the first and second elastic elements 12a, 12b and the adhesive coating 5.

After forming the elasticated laminate comprising the first continuous web 1 , the continuous covering web 16 and the two continuous elastic elements 12a, 12b, the elasticated laminate is cut into first and second laminate parts 17, 18 along a cutting line 19 following the wave-shaped curves 13a, 13b of the first continuous elastic element 12a and the second continuous elastic element 12b. The cutting line 19 is arranged between the first continuous elastic element 12a and the second continuous elastic element 12b along the intermediate wave segments 1 1 a, 1 1 b of the first continuous elastic element 12a and the second continuous elastic element 12b. The cutting line 19 crosses the first elastic element 12a only at the trailing end of each wave crest segment 8a of the first elastic wave-shaped curve 13a and at the trailing end of each wave trough segment 10a of the first elastic wave shaped curve 13a and crosses the second continuous elastic element 12b only at the leading end of each wave crest segment 8b of the second elastic wave- shaped curve 13b and at the leading end of each wave trough segment 10b of the second elastic wave shaped curve 13b. Hence, in accordance with the invention, the elastic elements will always be cut at opposite ends of the wave crest segments and wave trough segments.

As is seen in Fig. 8, the first continuous elastic element 12a is positioned slightly inside of the second continuous elastic element 12b along the linear parts of each wave crest segment and at each wave trough segment when seen from the longitudinal edges 2, 3 of the elasticated laminate. This arrangement is not a necessary feature of the invention. If found suitable the paths of the first and second continuous elastic elements 12a, 12b may coincide along the linear parts of the wave crest segments and wave trough segments.

The cutting line 19 runs between the first and second continuous elastic elements 12a, 12b along the intermediate segments 1 1 a, 1 1 b and inside of both the first and second continuous elastic elements 12a, 12b at the wave crest segments and wave trough segments.

A diaper 90 produced from the elasticated laminate of Fig. 8 is shown in Fig. 9. The construction of the diaper 90 differs from that of the diaper 70 shown in Fig. 7 in that elastic segments 22a, 23a and 22b, 23b are arranged both along the inclined portions 102,103 of the side edges 94,95 on the rear portion 93, and along the side edges 94,95 along the full length of the crotch portion 91 and also along the inclined portions 104,105 of the side edges 94,95 on the front portion 92. This means that the leg cuffs are elasticated along their complete length. In addition, the process illustrated in Fig. 8 results in double elastification of the side edges 94,95 along the diaper's 90 crotch portion 91 being formed by the linear wave crest and wave trough segments of the first and second continuous elastic elements 12a, 12b. The diaper 90 in Fig. 9 is shown without tape fasteners, to illustrate that tape fasteners may be omitted. Accordingly, the diaper 90 in Fig. 9 may be used in the form shown in Fig. 9 as an insert together with a supporting panty or a girdle or belt construction. Alternatively, the diaper 90 may be provided with any type of fastener as known in the art or may be formed into a pant diaper by creating seams at the waist to connect the front portion 92 with the rear portion 93.

Fig. 10 shows the production of an elasticated laminate web comprising an elastic element 12 applied in a curve pattern 13. The elasticated laminate web in Fig. 10 differs from that shown in Fig. 1 only in that the elastic element 12 is applied between the first continuous web 1 and the continuous covering web 16 with the wave-shaped curve of the first elastic element 13 being offset towards a side edge 3 of the elastic laminate instead of being centred about the longitudinal centre line 4 of the first continuous web 1 as is shown in Fig. 1 . Fig. 1 1 shows a base web 127 resulting from the elastic laminate in Fig. 10 after cutting the laminate in two parts 1 17, 1 18 and transposing and reassembling the parts 1 17, 1 18 in the manner illustrated by Figs. 2 and 3. The base web 127 differs from that shown in Fig. 4 in that the connecting seam 126 between the two parts 1 17, 1 18 of the base web 127 is displaced towards a side edge 29 of the base web 127 and in that the base web in Fig. 10 has a wider central part 150 consisting only of the first continuous web 1 than the corresponding central part 50 of the base web 27 shown in Fig. 4.

For the sake of simplicity, Figs. 10 and 1 1 show only one elastic element 12 being incorporated into the structure. However, it is to be understood that the base web in Fig. 1 1 could be provided with a second elastic element, in the manner shown in Fig. 8.

Fig. 12 shows a pant diaper 120 incorporating a topsheet structure 135 being formed from a base web produced according to the method in Figs. 10 and 1 1 . The pant diaper 120 is shown in a flat-out state from the body-facing side of the diaper. The most apparent difference when comparing the diapers shown in Figs 7 and 9 with that of Fig. 12 is that The Fig. 12 diaper has a wider crotch portion 121 and that no seam 126 can be seen along the centre line 4 of the topsheet structure 135. In the pant diaper shown in Fig. 12, the seam 126 is hidden beneath a raised barrier structure 138 that has been attached to the topsheet structure 135 after forming the base web 127 in Fig. 1 1 . The pant diaper 120 has one such raised barrier structure 138, 139 at each side of absorbent core 133a, 133b and extending the full length of the pant diaper. The raised barrier structures 138, 139 are preferably elasticated barriers that provide a gasketing seal against a wearer's body while being worn. The barrier structures 138, 139 may be a folded web containing one or more elongate elastic element arranged in the barrier in a pre-tensioned state. The barrier structures may be complicated constructions having a multi-limbed cross section or may be simple non-folded bands. The barrier structures 138, 139 may be liquid impermeable or at least resistant to liquid penetration but are preferably breathable.

The absorbent core 133a, 133b is shown as a dual layer structure with a lower hourglass shaped layer 133a extending into the front and rear parts 122, 123 of the pant diaper 120 and an upper, smaller layer 133b being positioned generally in the crotch portion 121 .

The pant diaper has transversely extending front and rear waist edges 142, 143 and generally longitudinally extending side edges 124, 125. Leg elastic 22, 23 is arranged along the side edges 124, 125 in the same manner as in the diaper shown in Fig. 7. In addition, the pant diaper 120 in Fig. 12 is shown to have waist elastic 155, 156 applied along the front and rear waist edges 142, 143. The waist elastic 155, 156 is shown to extend the full width of the pant diaper 120. However, it is to be understood that waist elastic may be arranged along only a part of one or both waist edges. The waist elastic 155, 156 may be in the form of an elastic band of any suitable kind, such as an elastic laminate, an elastic foam strip, elastic nonwoven material, non-elastic materials that have been elasticated with elastic threads or strings, etc. A common way of providing waist elastic is by attaching elastic elements such as threads, bands or strings in a pre- tensioned state between two layers of nonwoven, non-elastic material. All commonly used elastic materials such as natural or synthetic rubber elastic foam, etc. can be employed. Waist elastic of this type may be formed from two separate layers of nonwoven or may be made from a single layer of nonwoven that has been folded into a two-layer structure.

The pant diaper in Fig. 12 is shown with open side joins 160. In the in-wear configuration of the pant diaper 120, the front and back panels 122,123 are joined to each other along their side edges 128,129 by thermobonding, ultrasonic welding, glue strings or the like to form side joins 160. Side joins 160 are arranged in a pant diaper or other disposable absorbent pant-type article to connect the diaper's front portion 122 to the rear portion 123 and to form a pant having a waist opening and leg openings. The side joins 160 are intended to be arranged at the wearer's hips while wearing the pant diaper. The side joins 160 are preferably designed so that they can withstand the tensile forces which arise when the pant diaper is being put on and is being worn, but are made so that they can be torn apart or opened in a controlled manner when the pant diaper is taken off or to check if the diaper needs changing. In the latter instance, the side joins are preferably reclosable joins, as known in the art.

Fig. 13 shows the production of an elasticated laminate web comprising a continuous elastic element 12 applied in a curve pattern 13. The elasticated laminate web in Fig. 13 differs from that shown in Fig. 1 only in that the covering web 16 is an integral part of the first continuous web 1 . As is shown in Fig. 13, the adhesive coating 5 is applied in a curve pattern 6 along a first longitudinal edge 2 of the first continuous web 1 and the elastic laminate. The continuous elastic element 12 is attached to the adhesive coating in a curve pattern 13 being superposed on the adhesive curve pattern 6 in the same manner as shown in Fig. 1 . Thereafter, a part 135 of the first continuous web 1 constituting the covering web 16, is folded in over the elastic element 12 along a folding line 136 to cover both the elastic curve 13 and the curve pattern 6 of the adhesive coating 5. After the folding operation, the fold forms a second longitudinal edge 3 of the resulting elastic laminate.

The elastic laminate is subsequently cut along a cutting line 19 as described in connection with the elastic laminate in Fig. 1 and the two laminate parts 17, 18 are transposed and rejoined as shown in Figs 2-4.

It is to be understood that the elastic laminate in Fig. 13 may be provided with a second elastic element as described in connection with Fig. 8.

Fig. 14 shows the production of a further exemplifying elasticated laminate. The elasticated laminate web in Fig. 14 differs from that shown in Fig. 1 only in that it comprises elasticated raised barrier structures 138,139 also known as standing gathers, SG.

The elastic laminate in Fig. 14 is intended to form a topsheet structure in a finished absorbent article. Consequently, the first continuous web 1 and preferably also the liquid permeable covering web 16 are liquid permeable materials. The covering web 16 may be less hydrophilic or more hydrophobic than the first continuous webl but should preferably be breathable, i.e. permeable to air and water vapour.

The raised barrier structures 138, 139 are preferably resilient and/or elasticated barrier structures. In a finished absorbent article, such as that shown in Fig. 12, the raised barriers 138, 139 provide a gasketing seal against a wearer's body while the article is being worn. The barrier structures 138, 139 may be formed as separate components that are attached to the elasticated laminate, such as folded or non-folded bands of elastically stretchable and/ or resilient nonwoven, foam or similar or may be made from folded webs containing one or more elongate elastic element arranged in the barrier in a pre-tensioned state. The raised barrier structures 138, 139 may be formed by creating one or more longitudinal folds in the first continuous web 1 and/or in the covering web 16.

The raised barrier structures 138, 139 may be complicated constructions having a multi-limbed cross section or may be simple single-folded or non- folded bands. The barrier structures 138, 139 may be liquid impermeable or at least resistant to liquid penetration but are preferably breathable.

The elastic laminate web shown in Fig. 14 may be provided with a second elastic element as shown in Fig. 8.

The raised barrier structures are formed in the elastic laminate or attached to the elastic laminate prior to cutting the elastic laminate web into two elastic laminate parts 17, 18 along the cutting line 19. Cutting of the web is made in the same manner as is described in connection with Fig. 1 . The elastic laminate parts 17, 18 are then transposed and rejoined into an assembled topsheet base web as described in connection with Figs. 2-4.

An absorbent article produced using the base layer formed from the elastic laminate in Fig. 14 would be similar to that shown in Fig. 12 except for having the seam 126 being visible along the longitudinal centre line 4 of the topsheet.

Fig. 15 shows a further example of the manufacturing of an elasticated laminate web in accordance with the invention. The difference between the elasticated laminate web in Fig. 15 and that in Fig. 1 is that the continuous covering web 16 is elasticated and is offset towards an edge 2 of the first continuous elastic web 1 . The first continuous web 1 is fed in the machine direction, MD, and is provided with first and second continuous elastic elements 12a, 12b attached in a stretched state in the way shown in Fig. 8. However, the wave pattern 6 of the adhesive coating 5 has adhesive free notches 59 at each end of the wave crests and wave troughs. The notches 59 are arranged such that alternating ones of the elastic curves 13a, 13b of the elastic elements 12a, 12b extend over the notches 59 so that either the first elastic element 12a or the second elastic element 12b is not attached to the first continuous web 1 or the covering web 16 within the adhesive free area of the notch 59. When the elastic laminate web of Fig. 15 is cut along the cutting line 19, the cut will sever alternating ones of the first and second elastic elements 12a, 12b within the non-attached area of a notch 59 in the adhesive pattern. The severed ends of the elastic elements 12a., 12b will then retract of "snap back", leaving a shortened elasticated length in the elasticated web.

Elastic barrier elements 57, 58 are attached along the longitudinal edges of the continuous covering web 16. The elastic barrier elements 57, 58 may be in the form of one or more bands, threads or strings of elastically stretchable material, resilient material or a material that is both elastically stretchable and resilient. The elastic barrier elements 57, 58 may be preformed structures comprising elastic elements enclosed in a cover, such as a nonwoven cover.

The elastic barrier elements 57,58 may be enclosed in an edge-fold created in the continuous covering web 16. Alternatively the elastic barrier elements 57,58 may be attached to a non-folded edge portion of the continuous covering web 16.

The covering web 16 may be chosen among nonwoven materials, perforated and non-perforated plastic films, netting, and laminates and combinations of such materials. The plastic films may be breathable or non-breathable but are preferably breathable. In the finished disposable absorbent article, the covering web 16 will be applied along the longitudinal side edges of the article and will extend into the article's side panels in the portions of the article that will cover a wearer's hips and into the flexible elasticated side flaps that are formed along the article's leg edges. These parts of a diaper or other disposable absorbent garment will generally be located laterally outside of the absorbent core and will be in close body-contact while the garment is being worn. The covering web 16 will be placed on the inside, bodyfacing side of the absorbent article and the elastic barrier elements 57, 58 will form raised barriers at each longitudinal side edge of the absorbent article. It is preferred that the covering web 16 is liquid impermeable or at least hydrophobic, i.e. has a wetting angle of 90° or more, at least within the area forming the raised barriers. Plastic films and nonwovens made from thermoplastic polymers are inherently hydrophobic. However, the covering web may comprise a hydrophilic material that has been treated with a hydrophilising agent to render the web hydrophobic at least within the area of the raised barriers. A further possibility is that the covering web 16 is constituted of parts having different properties within different areas or that the covering web is coated or laminated with a liquid impermeable or at least liquid resistant barrier material.

After transposing the elasticated web parts 17, 18, applying absorbent cores 33, a topsheet 34 and tape tabs, 35, the finished diaper 160 will have the appearance shown in Fig. 16. The diaper 160 has elastic segments 22a, 23a and 22b, 23b arranged both along the inclined portions 102,103 of the side edges 164,165 on the rear portion 163, and along the side edges 164,165 along the full length of the crotch portion 161 and also along the inclined portions 104,105 of the side edges 164,165 on the front portion 162. As a result of parts of the elastic elements 12a, 12b being unattached to the first continuous web 1 and the continuous covering web 16 as shown in Fig. 15, the elastic segments 22a, 23a and 22b, 23b have snapped back at the ends closest to the diapers waist edges 166, 167 and do not extend all the way to the side edges 164, 165. As in the diaper shown in Fig. 9, resulting from the process illustrated in Fig. 8 double elastification of the side edges 164,165 is formed along the diaper's 160 crotch portion 161 by the linear wave crest and wave trough segments of the first and second continuous elastic elements 12a, 12b.

Moreover, as in the diaper shown in Fig. 12, the diaper in Fig. 16 has a wider crotch portion 161 and no seam 126 is visible along the centre line 4 of the topsheet structure 35. As in the pant diaper shown in Fig. 12, the seam 126 is hidden beneath a raised barrier structure 138. The raised barrier structures 138, 139 are formed by the continuous covering web 16 and the elastic barrier elements 57, 58 that are attached thereto and have the same function as the raised barriers in Fig 12. In order to illustrate how the shape of the wave shaped curve 5, 13 of the adhesive coating(s) 5, continuous elastic element(s) 12, 12a, 12b and cutting line 19 affects the shape of the finished absorbent article, one wave-length, t, of fours differently shaped curves a, b, c and d are shown in Fig. 17. The curves have been divided into ten equally long parts showing that:

- curve a has linear wave crest and wave trough segments being 4/10 of the wave-length, t,

- curve b has linear wave crest and wave trough segments being 3/10 of the wave-length, t,

- curve c has linear wave crest and wave trough segments being 2/10 of the wave-length, t, and

- curve d has linear wave crest and wave trough segments being 1/10 of the wave-length, t. In accordance with the invention, the length in the machine direction, MD of the linear parts of the wave crest segments and the wave trough segments preferably constitute from 1/10 to 4/10 of the wave-length, t, and more preferably from 2/10 to 3/10 of the wave length, t.

For curve a, the contour of the finished absorbent article will be as shown in Fig. 18a.

For curve b, the contour of the finished absorbent article will be as shown in Fig. 18a. For curve a, the contour of the finished absorbent article will be as shown in Fig. 18c.

For curve a, the contour of the finished absorbent article will be as shown in Fig. 18d.

As is seen in Fig. 18a, the crotch portion 31 will be relatively long. The crotch portion 31 of the article shown in Fig 18d is relatively short and the linear parts of the side edges at the waist edge are correspondingly short. Figs. 18a and 18b illustrate intermediate shapes of useful cutting/elastic curves.

By selecting the wave-length, the shape of the cutting/elastic curve as shown in Figs. 18a-18d, the amplitude of the curve and the width of the first continuous web extending outside of the cutting curve in the machine direction, MD, the silhouette of the absorbent article may be designed as desired depending on the particular intended use for the article. Accordingly, the absorbent article may be shaped to fit any size of wearer from infants to adults and may be formed with a wide or narrow crotch portion depending on use. Absorbent articles may be made in accordance with the invention for use as diapers for children and adults, for use as light incontinence inserts or garments, or as feminine sanitary garments. Figs. 16 and 18 a-d show curves for the cutting line 19. The cutting line will have the same general curve shape, i.e. the same wave length, t, and amplitude, A, as the elastic element or elements. However, in the finished disposable absorbent article, the elastic curve or curves will have an at least slightly rounded shape at the ends of the wave crest segments and wave trough segments where the elastic curve changes direction. The cutting line may be chosen to follow the more rounded shape of the elastic curve or curves or may be formed with a less rounded shape or even with perfectly linear segments as illustrated in Figs. 17 and 18 a-d.

Claims

1 . Method for producing an absorbent article comprising a base web (27) forming a continuous and coherent external layer of the absorbent article characterised by

• feeding a first continuous web (1 ) along a production path in a machine direction, MD, the web (1 ) having a longitudinal centre line (4) in the machine direction, MD,

• applying an adhesive coating (5) to a predetermined portion (6) of the first continuous web (1 ),

• feeding a first continuous elastic element (12) in the machine direction, MD, along a wave-shaped curve (13), the waves having equal wave length, t, and equal amplitude, A, each wave having a crest (7) comprising a wave crest segment (8) having a length of from 10% to 40% of the wave length, t, preferably a length of from

20% to 30% of the wave length, I, and a trough (9) comprising a wave trough segment (10) having a length equal to that of the wave crest segment (8), and having intermediate wave segments (1 1 ) connecting the wave crest segments (8) and the wave trough segments (10), the intermediate wave segments (1 1 ) having a leading side (14) in the machine direction, MD, and a trailing side (15) in the machine direction, MD,

attaching the first continuous elastic element (12) to the adhesive coating (5) on the first continuous web (1 ) along the wave-shaped curve (13) of the first continuous elastic element (12),

forming an elasticated laminate having first and second longitudinal edges (2,3) running parallel to the machine direction, MD, by applying a continuous covering web (16) to the first continuous web (1 ) to cover the continuous elastic element (12) and the adhesive coating (5) cutting the elasticated laminate into first and second laminate parts (17,18) along a cutting line (19) following the wave-shaped curve (13) of the first continuous elastic element (12), the cutting line (19) being arranged at a distance of not more than 70 mm from the first continuous elastic element (12) and being arranged always on the same one of the leading side (14) of each intermediate wave segment (1 1 ) or the trailing side (15) of each intermediate wave segment (1 1 ) of the elastic wave-shaped curve (13) and crossing the first elastic element (12) always only at the same one of the leading end (20a) of each wave crest segment (8) of the elastic wave-shaped curve (12) and the leading end (20b) of each wave trough segment (10); or crossing the first elastic element (12) always only at the same one of the trailing end (21 a) of each wave crest segment (8) of the elastic wave-shaped curve (12) and the trailing end (21 b) of each wave trough segment (10), separating the first and second laminate parts (17,18) along the cutting line (19),

moving the first and/or second laminate parts (17,18) in the cross machine direction, CD, perpendicular to the machine direction, MD, bringing the first and second longitudinal edges (2,3) of the elastic laminate together, and shifting the first and second laminate parts (17,18) relative to one another in the machine direction, MD, by an odd multiple of half a wavelength, t,

bonding the first and second laminate parts (17,18) to each other along the longitudinal edges (2,3) of the elastic laminate to form a continuous coherent base web (27) having regularly alternating wide portions (30) and narrow portions (31 ),

intermittently applying absorbent cores (33) to the base web (27) at each narrow portion (31 ),

forming individual absorbent articles by severing the base web (27) and any component overlapping with the base web in the cross machine direction, CD, between the absorbent cores (33) at the wide portions (30) of the base web (27).

2. Method for producing an absorbent article according to claim 1 , wherein the wave crest segments (8) and the wave trough (10) segments extend linearly along at least 60% of their length, the linear part of each wave crest segment (8) and each wave trough segment (10) being arranged parallel with the first and second longitudinal edges (2,3) of the elastic laminate. 3. Method for producing an absorbent article according to claim 2, wherein the wave crest segments (8) and the wave trough segments (10) extend linearly along at least 75% of their length, the linear part of each wave crest segment (8) and each wave trough segment (10) being arranged parallel with the first and second longitudinal edges (2,

3) of the elastic laminate.

4. Method for producing an absorbent article according to claim 1 , 2 or 3, wherein the intermediate wave segments (1 1 ) extend linearly along at least 60% of their length.

5. Method for producing an absorbent article according to claim 4, wherein the intermediate wave segments (1 1 ) extend linearly along at least 75% of their length.

6. Method for producing an absorbent article according to any one of the preceding claims, wherein the first continuous web (1 ) is a liquid permeable web.

7. Method for producing an absorbent article according to any one of the preceding claims, wherein the covering (16) web is a liquid permeable web.

8. Method for producing an absorbent article according to claim 7, wherein both the first continuous web (1 ) and the covering web (16) are liquid permeable webs and wherein the absorbent cores (33) are covered by a liquid impermeable layer.

9. Method for producing an absorbent article according to claim 8, wherein the liquid impermeable layer is a continuous liquid impermeable web (34).

10. Method for producing an absorbent article according to any one of the preceding claims, wherein the covering web (16) comprises an integral portion (135) of the first continuous web (1 ) that is folded in over the first continuous web (1 ), the adhesive coating (5) and the first elastic element (12).

1 1 . Method for producing an absorbent article according to any one of claims 1 -9, wherein the covering web (16) comprises a continuous web that is separate from the first continuous web (1 ).

12. Method for producing an absorbent article according to any one of the preceding claims, wherein the wave-shaped curve (13) of the first elastic element (12) is centred about the longitudinal centre line (4) on the first continuous web (1 ).

13. Method for producing an absorbent article according to any one of claims 1 -1 1 , wherein the wave-shaped curve (13) of the first elastic element (12) is offset towards a side edge (2) of the first continuous web (1 ).

14. Method for producing an absorbent article according to any one of the preceding claims, wherein the first elastic element (12) is applied to the first continuous web (1 ) while held in a tensioned state.

15. Method for producing an absorbent article according to any one of the preceding claims, wherein the method comprises: feeding a second continuous elastic element (12b) in the machine direction, MD along a second wave-shaped curve (13b) having the same wave length as the first wave-shaped curve (13a) of the first elastic element (12a), the second wave-shaped curve (13b) having wave crest segments and wave trough segments and intermediate wave segments between the wave crest segments and the wave trough segments corresponding to the wave crest segments (8) and wave trough segments (10) and intermediate wave segments (1 1 ) of the first wave-shaped curve (13a) of the first elastic element (12a) the second wave-shaped curve (13b) of the second elastic element being spaced in the machine direction, MD, by a distance, d, of 10-70 mm from the first elastic element (12a) along the intermediate wave segments (1 1 a) of the first elastic element (12a),

attaching the second continuous elastic element (12b) to the adhesive coating (5) on the first continuous web (1 ),

forming an elasticated laminate by applying the continuous covering web (16) to the first continuous web (1 ) to cover the first elastic element (12a) and the second elastic element (12b) and the adhesive coating (5),

cutting the elasticated laminate into first and second laminate parts (17,18) along a cutting line (19) following the wave-shaped curves (13a, 13b) of the first continuous elastic element (12a) and the second continuous elastic element (12b), the cutting line (19) being arranged between the first continuous elastic element (12a) and the second continuous elastic element (12b) along the intermediate wave segments (1 1 a, 1 1 b) of the first continuous elastic element (12a) and the second continuous elastic element (12b) and always crossing the second continuous elastic element (12b) only at the other of the leading end and the trailing end of each wave crest segment of the second elastic wave-shaped curve (13b) and always only at the other of the leading end or the trailing end of each wave trough segment of the second elastic wave shaped curve (13b) as compared to the first elastic wave shaped curve (13a).

16. Method for producing an absorbent article according to any one of the preceding claims, wherein the method comprises forming elasticated barriers (138,139) extending in the machine direction, MD on each side of the first elastic wave shaped curve (13) before cutting the elastic laminate into two parts (17,18), the cutting line (19) being arranged laterally inside of the elasticated barriers.

17 Method for producing an absorbent article according to claim 16, wherein the elasticated barriers (138,139) are formed by attaching elastic barrier elements (57,58) along the edges of the continuous covering web (16) before applying the continuous covering web to the first continuous web 1 .

18. A continuous base web (27) for incorporation as a coherent surface layer in a disposable absorbent article, the base web (27) having a longitudinal direction with a longitudinal centre line (4) and side edges (28,29) extending in the longitudinal direction, characterised in that the base web (27) consists of two parts (17,18) that are joined together in a seam (26) extending in the longitudinal direction and comprises a first continuous web (1 ) and a continuous covering web (16) laminated with the first continuous web (1 ) and that the side edges (28,29) of the base web (27) are wave shaped, the waves being of equal length and amplitude and being synchronized so that the base web (27) has regularly alternating wide portions (30) constituting front and back body portions and narrow portions (31 ) constituting crotch portions in the base web (27) and comprising first elastic elements arranged along the side edges of the base web in discrete first segments (22,23) with one first segment (22,23) extending along each side edge (28,29) in each crotch portion and into one of the front or back body portions.

19. A continuous base web (27) according to claim 18, wherein the base web (27) comprises second elastic elements arranged along the side edges of the base web in second discrete segments (22b, 23b) with one segment (22b, 23b) extending along each side edge (28,29) in each crotch portion and into the other of the front or back body portions with the first and second discrete elastic segments (22a, 23a, 22b, 23b) extending parallel to each other in each crotch portions.

20. A continuous base web (27) according to claim 19, wherein the base web (27) comprises elastic barrier elements (57,58) attached along the edges of the continuous covering web (16).

21 . A disposable absorbent article (70; 90; 120; 160) having a longitudinal direction and a transverse direction, side edges (84,85; 94,95; 124,125;

164,165) extending in the longitudinal direction and waist edges (76,77; 96,97; 142,143; 166,167) extending in the transverse direction, a front body portion (72; 92; 122; 162), a rear body portion (73; 93; 123; 163) and a crotch portion (71 ; 91 ; 121 ; 161 ) between the front body portion (72; 92; 122; 162) and the rear body portion (73; 93; 123; 163) and comprising a liquid permeable topsheet structure (35; 135) and a liquid impermeable backsheet structure and absorbent core enclosed between the topsheet structure (35; 135) and the backsheet structure, characterised in that the absorbent article (70; 90; 120; 160) has first elastic elements arranged as continuous elastic segments (22, 23) along the side edges (84,85; 94,95; 124,125; 164,165) at the crotch portion (71 ; 91 ; 121 ; 161 )and along the side edges (84,85; 94,95; 124,125; 164,165) of one of the front or rear body portions(72,73; 92,93; 122,123; 162,163), each elastic element (22,23)having a linear segment in the crotch portion (71 ; 91 ; 121 ; 161 ).

22. Absorbent article according to claim 21 , wherein second elastic elements are arranged as continuous elastic segments (22b, 23b) along the side edges (94,95; 164,165) at the crotch portion (91 ; 161 ) and along the side edges (94,95; 164,165) of the other of the front or rear body portions (92,93; 162,163), the absorbent article having dual, parallel elastic elements in the crotch portion (91 ; 161 ) and single elastic elements in the front and rear body portions (92,93; 162,163).

23. Absorbent article according to claim 21 or 22, wherein the topsheet structure (35; 135) is a base web (27) according to claims 18-20 or a base web (27) produced according to the method in any one of claims 1 -17.

24. Absorbent article according to claim 21 or 22, wherein the backsheet structure is a base web (27) according to claims 18 or 19 or a base web (27) produced according to the method in any one of claims 1 -16.