Field of the invention The present invention concerns an absorbent article, such as a sanitary napkin, a panty liner or an incontinence protector, which absorbent article comprises a liquid-permeable upper layer, a liquid-impermeable lower layer and an absorbent structure arranged between the upper layer and the lower layer, and which absorbent article has an essentially elongated shape, a longitudinal direction, a transverse direction, two essentially transverse end edges and two essentially longitudinal side edges, wherein a lower surface of the liquid-impermeable lower layer is intended to lie against the undergarment of a user and is at least partly provided with an adhesive.

Background to the invention A variety of absorbent articles, such as sanitary napkins, panty liners and incontinence protectors, are found on the market today, with differing shapes and dimensions. Such absorbent articles are designed to absorb and retain bodily fluids and, in use, are intended to be placed in the crotch portion of a user's undergarment. To prevent the absorbent article from moving substantially relative to the undergarment and to reduce the risk of leakage, the majority of today's absorbent articles can be fastened in the undergarment. Normally, at least one fastening surface in the form of a layer comprising an adhesive is arranged on that surface of such an absorbent article which is intended to lie against the undergarment. In use of the absorbent article, the adhesive adheres to an undergarment.

Many known absorbent articles comprise a pressure-sensitive adhesive which is applied in e.g. one or more strands, stripes, points or similar, as well as in different positions on that surface of the article which is intended to lie against an undergarment. Such articles are known through e.g. US 3 888 255, WO 03/072004 and WO 00/37015. Furthermore, it is known through e.g. CA 2 126 252 to apply an adhesive in a pattern, and it is known through e.g. WO 97/12572 to apply an adhesive as a complete coating.

To prevent the adhesive which is intended to adhere to an undergarment from becoming dirty or from undesirably adhering to other objects during transport and storage, the adhesive is usually protected with a special detachable protective strip of paper or similar which has been treated with a release substance. The protective strip is also used to prevent the adhesive from drying out before use.

Currently, absorbent articles of the above-mentioned type are often packaged individually in individual packaging wrappers, so that so-called "unit packages" of the absorbent articles are obtained. Such unit packed products allow absorbent articles to be hygienically and discretely kept in a bag, trouser pocket or similar. Furthermore, the absorbent article in a unit package is usually folded along two transverse fold lines, so as to minimize the space required for storage. A "three-folded" article is thus formed, with a rear portion, a centre portion and a front portion. Examples of such folded absorbent articles are given in e.g. WO 89/02728, US 4 556 146 and EP 0 532 649.

It is also common to provide the absorbent articles of the above-mentioned type with fastening flaps (also called "wings") at the side edges of the article, so as to minimize the risk for side-edge leakage and to improve the security of attachment. These fastening flaps help to securely position the absorbent article, in that they are intended to be folded around the leg edges of the user's undergarment and fastened against the outside of the undergarment by means of fastening surfaces in the form of coatings comprising an adhesive, which are arranged on the fastening flaps. Examples of sanitary napkins with fastening flaps are given in e.g. SE 455668, US 4 701 178 and US 4 285 343.

An adhesive of an absorbent article for adhesion to an undergarment exhibits an adhesive capacity (stickiness or "tackiness"). Such an adhesive further exhibits an adhesive strength ("peel-strength") to a material to which it adheres. The adhesive strength of an adhesive to a given material to which it adheres is completely dependent on the adhesive capacity (stickiness or "tackiness") of that adhesive. The adhesive strength to a certain material is therefore an indirect measure of the adhesive capacity (stickiness) of the adhesive. The adhesive strength is, however, different for different materials.

The adhesive strength of an adhesive of an absorbent article to an undergarment is a parameter which has great influence on how user-friendly the absorbent article is. A certain adhesive strength is required so that an absorbent article shall remain in place in a user's undergarment. If the absorbent article does not retain its position due to an adhesive strength which is too low, a risk of leakage may arise. Furthermore, the absorbent article can thereby partly or wholly loosen from the undergarment and instead fasten to e.g. the user's body, whereby the risk arises that the user experiences a feeling of discomfort.

A number of factors influence the adhesive strength of an adhesive of an absorbent article to an undergarment that is required for secure placement of the absorbent article.

Examples of such factors are the absorbent article's shape, dimensions and materials. As absorbent articles belonging to different product categories, such as sanitary napkins, panty liners and incontinence protectors, have different designs, the adhesive strength which is required for secure placement can be different for absorbent articles belonging to different product categories. However, the adhesive strength required for secure placement can also vary for absorbent articles which have different designs within the same product category.

Furthermore, the adhesive strength of an adhesive to an undergarment which is required for secure placement can vary between different portions of an absorbent article. For example, folding about the two fold lines in a "three-folded" absorbent article means that the rear portion and the front portion of "three-folded" articles tend to fall back to the positions they had when the article was folded, whereupon the adhesive faces the genitals of the user. If this occurs while such an article is placed in the crotch portion of a user, the article fastens to the user's genitals, which is experienced by the user as most uncomfortable. Consequently, to guarantee secure placement, stronger fastening of the rear portion and the front portion of a "three-folded" article is required than of the centre portion.

Furthermore, the adhesive strength of an adhesive of the fastening flaps to an undergarment which is required for secure placement can differ from the adhesive strength which is required of an adhesive on the other portions of an absorbent article for secure placement.

The adhesive strength of an adhesive to an undergarment which is required for secure placement also depends upon the undergarment material. Different adhesive capacities of the adhesive are thus required for different qualities of textile.

However, neither is it user-friendly if the adhesive strength of an adhesive to an undergarment is as high as possible. Adhesive strengths which are too high can lead to difficulties with removing the absorbent article from the undergarment after use. This can possibly also lead to the undergarment being negatively affected, e.g. by colour or material of the undergarment being removed with the absorbent article when it is removed from the undergarment, or that glue residues remain in the underwear.

The problems of excessively high and excessively low adhesive strengths of an adhesive to an undergarment must often be weighed against one another, with the aim of finding a level of adhesive capacity of the adhesive which is as optimal for a given absorbent

article as possible. In most cases it is desirable that the adhesive exhibits an adhesive strength to an undergarment which provides secure placement, but which is not higher than that required for secure placement so that the problems of excessively high adhesive strength are avoided as far as possible.

Despite innumerable efforts to try to provide optimal adhesive strengths of adhesives to undergarment materials, it is common that the adhesive strengths of those articles found on the market today are too high or too low. Problems of adhesive strength exist especially often with the "three-folded" absorbent articles found on the market today. With some such articles, the problem exists that the adhesive strength is too low in the rear portion and the front portion, whereby - in use - these portions tend to fall back to those positions which they had when the article was folded. In other such absorbent articles, the problem exists that the adhesive strength in the centre portion is higher than that which is required for secure placement.

Thus, there still exists a need for a simple and reliable way to control the adhesive capacity of an adhesive of an absorbent article, such as a sanitary napkin, a panty liner or an incontinence protector, which adhesive is intended for adhesion to an undergarment, to one or more desired levels to provide an absorbent article in which the adhesive exhibits one or more desired levels of the adhesive strength to an undergarment material.

Summary of the invention

One object of the present invention is to provide an absorbent article, such as a sanitary napkin, a panty liner or an incontinence protector, in which the adhesive capacity of an adhesive has been controlled in a simple manner to one or more levels during production of the absorbent article.

This object is achieved by an absorbent article, such as a sanitary napkin, a panty liner or an incontinence protector, said absorbent article comprising a liquid-permeable upper layer, a liquid-impermeable lower layer and an absorbent structure arranged between the upper layer and the lower layer, said absorbent article having an essentially elongated shape, a longitudinal direction, a transverse direction, two essentially transverse end edges and two essentially longitudinal side edges, wherein a lower surface of the liquid- impermeable lower layer is intended to lie against the undergarment of a user and is at least partly provided with an adhesive, and wherein the adhesive is a UV-curable adhesive, which exhibits an adhesive capacity which depends on the dose of UV-radiation to which it has been exposed during production of the absorbent article.

According to one aspect of the present invention, the adhesive is a pressure-sensitive adhesive.

According to a further aspect of the present invention, the adhesive is a hot melt adhesive.

In one embodiment, the adhesive is arranged on said lower surface of the liquid- impermeable lower layer in at least one strand substantially in the longitudinal direction of the absorbent article.

In a variant, the adhesive is arranged on said lower surface of the liquid-impermeable lower layer in three strands substantially in the longitudinal direction of the absorbent article.

In another variant, the adhesive is arranged on said lower surface of the liquid- impermeable lower layer in at least one strand substantially in the transverse direction of the absorbent article.

In yet another variant, the adhesive is arranged over substantially the entire lower surface of the liquid-impermeable lower layer.

According to one aspect of the invention, said lower surface of the absorbent article comprises at least two areas which are at least partly provided with the adhesive, wherein the adhesive capacity of the adhesive differs between at least two of said areas in that the dose of UV-radiation to which the adhesive has been exposed differs between the at least two of said areas.

According to another aspect of the invention, the absorbent article has at least one transverse fold line, wherein the absorbent article is intended to be folded along the at least one transverse fold line in its packaged state, and wherein the absorbent article is divided into at least two portions in its longitudinal direction, substantially defined by the at least one transverse fold line.

In one variant, each of said at least two portions coincides with one of said at least two areas.

In one embodiment, the absorbent article has two transverse fold lines, wherein the absorbent article is intended to be folded along the two transverse fold lines in its packaged state, and wherein the absorbent article is divided into a first end portion, a second end portion and a centre portion situated between the end portions, substantially defined by the two transverse fold lines and the adhesive capacity of the adhesive in said end portions is higher than the adhesive capacity of the adhesive in said centre portion.

According to one aspect of the invention, the adhesive capacity of the adhesive is such that the adhesive strength of the adhesive to an undergarment material lies in the range 2.0 -3.0 N/product for the end portions and in the range 1.5 - 2.5 N/product for the centre portion.

In one variant, the adhesive capacity of the adhesive in said first end portion is higher than the adhesive capacity of the adhesive in said second end portion.

In a further variant, the adhesive capacity of the adhesive in said second end portion is higher than the adhesive capacity of the adhesive in said first end portion.

According to one aspect of the present invention, the absorbent article further comprises at least one fastening flap at each side edge, which fastening flap is intended to be folded around an edge of a leg-opening of the undergarment of a user and which fastening flap comprises said adhesive on at least a part of a surface which is intended to face the user's undergarments.

In one variant, the adhesive on the surface of each fastening flap which is intended to face a user's undergarment exhibits an adhesive capacity which differs from the adhesive capacity of the adhesive on said lower surface of the liquid-impermeable lower layer.

According to a further aspect of the present invention, at least one protective layer is arranged over the adhesive, said at least one protective layer having a surface which is treated with a release substance, said surface lying detachably against the adhesive.

Further features of the present invention will become apparent from the following detailed description, which shall be interpreted with the help of the appended drawings. It should, however, be noted that the drawings are provided for the purpose of illustration only, and that they do not limit the invention. Neither are the drawings necessarily drawn to scale, and - unless otherwise stated - illustrate only conceptually the structures and procedures described herein.

Brief description of the drawings

In the drawings, similar reference numbers denote similar elements throughout the different figures, and

Fig. 1 is a plan view of a first embodiment of an absorbent article according to the present invention, in which a lower surface is shown, which is intended to face a user's undergarment,

Fig. 2 is a cross-sectional view along line II-II in Figure 1,

Fig. 3 is a plan view similar to that in Figure 1, but showing a variant of the first embodiment of the invention,

Fig. 4 is a plan view similar to that in Figure 1, but showing a further variant of the first embodiment of the invention,

Fig. 5a is a plan view of a second embodiment of an absorbent article according to the present invention, in which an upper surface is shown, which is intended to face the body of a user;

Fig. 5b is a plan view of the absorbent article in Fig. 5a after a first fold,

Fig. 5c is a plan view of the absorbent article in Fig. 5a after a second fold, and

Fig. 6 is a plan view similar to that in Fig. 1, but showing a third embodiment of the invention.

Detailed description of the invention

Figure 1 and Figure 2 show a plan view and a cross-sectional view, respectively, of a first embodiment of an absorbent article 1, such as a sanitary napkin, a panty liner or an incontinence protector, according to the present invention. The absorbent article 1 has a

conventional construction and comprises a liquid-permeable upper layer 2, a liquid- impermeable lower layer 3 and an absorbent structure 4 arranged between the upper layer and the lower layer 2,3. In use, the liquid-permeable upper layer 2 is intended to face a user, and the liquid-impermeable lower layer 3 is intended to face a user's undergarment.

Usually, both layers 2,3 extend out from the edges of the absorbent structure 4 and protruding portions 5 of both layers 2,3 are thereby joined to one another around the periphery of the absorbent structure 4, e.g. by gluing, sewing or by welding with heat or ultrasound.

The material in the liquid-permeable upper layer 2 may be of any suitable type, and can for instance comprise a non-woven material, e.g. spunbond, meltblown, carded material, hydroentangled material, wet-laid material etc. Suitable non-woven materials can be composites of natural fibres, cotton fibres, artificial fibres such as polyester, polyethylene, polypropylene, viscose etc., or a mixture of natural and artificial fibres. Furthermore, the material in the liquid-permeable upper layer 2 may comprise tow fibres, which can be bound to each other in a bonding pattern, as described in EP-A-I 035 818. Further examples of materials which are suitable for the liquid-permeable upper layer 2 are perforated plastic films, nets and open-cell or perforated foam materials. Different types of laminates, e.g. laminates of non-woven material and plastic film may also be used. Materials which are suitable for the liquid-permeable upper layer 2 should be soft and non-irritating to the skin, and should be readily penetrated by bodily fluids, e.g. urine and menstrual fluid. However, it is not necessary that the liquid-permeable upper layer 2 is a separate material layer, but rather this layer 2 can instead be an integrated portion of the absorbent structure 4. Furthermore, the upper layer 2 can be different in different portions of the absorbent article 1. Often, for example, a material especially suitable for admission of fluid is arranged centrally and a specially soft and comfortable material is arranged along the longitudinal side edges 1 of the article 1.

The liquid-impermeable lower layer 3 is formed from a liquid-impermeable material, such as a thin plastic film, e.g. a polyethylene film or a polypropylene film, a non-woven material which is made liquid-impermeable through coating or treatment with a liquid- impermeable material, a hydrophobic non-woven material which resists liquid penetration or a laminate of a plastic film and a non-woven material. Other types of liquid-barrier- materials may of course also be used, such as e.g. closed-cell plastic foams, various liquid-barrier laminates etc. In order that the absorbent article 1 should feel airy and comfortable to wear, the liquid-impermeable layer 3 suitably allows air and water vapour

to be transported out from the absorbent structure 4. Examples of materials which are breathable and which are suitable for use as the liquid-impermeable lower layer 3 are porous polymer films, non-woven laminates of layers of spunbond and meltblown, laminates of porous polymer films and non-woven materials. The liquid-impermeable lower layer 3 can be elastic or inelastic. Furthermore, the liquid-impermeable lower layer 3 can be an integrated portion of the absorbent structure 4, and can e.g. be formed from a skin-like surface on an absorbent foam body.

The absorbent article 1 has a conventional, essentially elongated shape, and is defined in the plane by two essentially transverse end edges 6, 7 as well as two essentially longitudinal side edges 8, 9 running between these. Furthermore, the absorbent article 1 has a longitudinal direction x and a transverse direction y. In the longitudinal direction x, the absorbent article 1 has a first and a second end part 10,11 as well as a centre part 12 lying between the end parts 10,11. The so-called wetting area, which is the area of an absorbent article which is intended to first receive an exuded bodily fluid, is usually located within the centre part 12 (also called the crotch part). The various parts 10-12 do not however usually have definite boundaries. In Figures 1 and 2, the end parts 10,11 are completely symmetric, whereby whichever of the two end parts 10,11 can face forwards on a user when worn. Both the size and position of the various parts 10-12 in the longitudinal direction x are thereby first determined upon use. In alternative embodiments, however, the end parts 10,11 can be asymmetrically shaped. For example, the first end part 10 can be longer than the second end part 11, whereby the first end part 10 is intended to face rearwards on a user when worn, and the second end part 11 forwards.

When the absorbent article 1 is used, a lower surface 13 of the liquid-impermeable lower layer 3 is intended to lie against the undergarment of a user. The lower surface 13 is at least partly provided with an adhesive 14 which adheres to the undergarment of the user while in use.

As mentioned in the introduction, the adhesive strength of an adhesive of an absorbent article to a material to which it adheres is completely dependent on the adhesive capacity (stickiness or "tackiness") of the adhesive. In this way, the adhesive strength to a certain material is therefore an indirect measure of the adhesive capacity (stickiness) of the adhesive. The value of the adhesive strength (or "peel-strength") of an adhesive is given herein as the force which is required to separate an area of a carrier material from another material after adhesion, said area being substantially coated with the adhesive. The adhesive strength differs, however, from material to material. To reduce the risk of

remnants of the adhesive 14 being left behind on the undergarment after use, it is however important that the adhesive 14 exhibits a higher adhesive strength to the liquid- impermeable lower layer 3 than to an undergarment.

A number of factors influence the level of the adhesive capacity (stickiness) of the adhesive 14 which is optimal to avoid the above-mentioned problems with excessively high or excessively low adhesive strength to an undergarment as much as possible. The problems of excessively high and excessively low adhesive strength of an adhesive to an undergarment must often be weighed against one another, with the aim of finding a level of the adhesive capacity of the adhesive which is as optimal as possible for a given absorbent article. The optimal adhesive capacity of an adhesive of absorbent articles belonging to various product categories, such as sanitary napkins, panty liners and incontinence protectors, can vary. Furthermore, the optimal adhesive capacity may also depend upon which type of textile in the undergarment material is prevalent in a given market.

Examples of ranges in which the optimal adhesive strength of an adhesive to an undergarment material lie are 1.5-3.0 N/product for sanitary napkins, panty liners and incontinence protectors, i.e. the optimal adhesive capacity of the adhesive is such that the adhesive strength of the adhesive to an undergarment material lies in the region of 1.5-3.0 N/product. However, the optimal adhesive strength of an adhesive to an undergarment material can differ between absorbent articles in the same product category, but which have different designs.

In accordance with the invention, the adhesive 14 of the absorbent article 1 is a UV- curable adhesive, which exhibits an adhesive capacity which depends on the dose of UV- radiation to which it has been exposed during production of the absorbent article 1. After application to the absorbent article 1, the adhesive 14 is exposed to UV-radiation by means of e.g. one or more UV-lamps, whereupon curing of the adhesive 14 occurs. In this way, the adhesive capacity of the adhesive 14 can be controlled to one or more desired levels by controlling the dose of UV-radiation which is applied to the adhesive 14 upon curing. A given desired level of adhesive capacity of the adhesive 14 is thereby produced during curing of the adhesive 14 by applying a suitable dose of UV-radiation, which produces the desired level of adhesive capacity. In that the absorbent article 1 comprises the UV-curable adhesive 14, the adhesive capacity of which has been controlled to one or more levels during curing, the absorbent article 1 exhibits one or more levels of adhesive strength to an undergarment material.

The expression "dose of UV-radiation" is used herein to indicate the amount of radiation energy which is applied to the adhesive [mJ/m ² ]. The dose of UV-radiation which is applied to the adhesive 14 can be controlled by adjustment of the intensity of the UV- lamp or UV-lamps which is/are used, by the number of UV-lamps which the adhesive passes and/or by adjustment of the web speed of the web on which the absorbent article 1 is produced (see also the example given below), whereby the exposure time of the adhesive to the UV-lamp is controlled.

Furthermore, the adhesive 14 is a UV-curable adhesive which does not substantially harden afterwards, i.e. when the curing is completed during production, the adhesive capacity is substantially set at a given level. In this way, the adhesive capacity of the adhesive 14 is not significantly affected by ageing, and the adhesive 14 thereby exhibits an adhesive capacity which is stable over time. Furthermore, the adhesive 14 is preferably a UV-curable adhesive which is cured with UVC-light (light with wavelength between 200 and 280 nm). The adhesive capacity of the adhesive 14 is thereby not affected by sunlight, as this consists of UVB-light (light with wavelength between 280 and 320 nm) and UVA-light (light with wavelength between 320 and 400 nm).

Preferably, the UV-curable adhesive 14 is a pressure-sensitive adhesive, or a hot melt adhesive. Even more preferably, the UV-curable adhesive 14 is a pressure-sensitive hot melt adhesive.

Normally, pressure-sensitive adhesives are characterized by their ability to tolerate creep-deformation or shear-deformation at high loads and/or high temperatures, at the same time as they exhibit sufficient adhesive strength. Resistance to creep-deformation or shear-deformation is normally the result of a high inner cohesive strength. Hot melt adhesives are compositions which are solid at room temperature, but when they are heated, transform into fluid form or melt form and can thus be applied to a substrate.

Preferred adhesives can for example be acrylic-based or rubber-based. Sanicare UV 4101 (obtainable from Henkel KGaA, Dϋsseldorf, Germany) and Ecomelt UV Nl (obtainable from Henkel KGaA, Dϋsseldorf, Germany) are examples of preferred acrylic- based UV-curable pressure-sensitive hot melt adhesives whose adhesive capacity can be controlled by the dose of UV-radiation to which it is exposed. Ecomelt UV N4 (obtainable from Henkel KGaA, Dϋsseldorf, Germany) is an example of a preferred rubber-based UV- curable adhesive.

WO 96/29374 describes pressure-sensitive adhesives which are UV-activated in a solvent-free system, as well as their precursors. For example, acrylate prepolymers are described therein, whose adhesive capacity upon UV-radiation with a certain intensity depends on the time of irradiation. However, the adhesives given in WO 96/29374 are intended to be used within the medicinal field, especially within the field of medical dressings, as well as for the securing of industrial components together, such as electronic devices. Use within the field of hygiene products is not mentioned therein, which places completely different requirements on the properties of the adhesives used, as compared to the requirements which are made within the fields addressed by WO 96/29374.

The adhesive 14 is preferably applied at essentially the same amount per unit area, i.e. the thickness of the layer of adhesive is preferably essentially constant, in all areas of the surface 13 of the absorbent article 1 where the adhesive 14 is applied. If the amount of adhesive 14 which is applied per unit area is not essentially the same, and the layer of adhesive 14 does not therefore have a constant thickness, the risk arises that the level of curing will not be uniform. Furthermore, an uneven curing gradient can arise if an excessively thick layer of adhesive is used. It is normally not preferable to have layers of adhesive above 20-25 g/m ² .

In the first embodiment shown in Figure 1 and Figure 2, the adhesive 14 is arranged on the lower surface 13 of the liquid-impermeable lower layer 3 in a continuous strand 15 substantially in the longitudinal direction x of the absorbent article 1. However, in alternative embodiments, the adhesive 14 can be arranged in two or more strands 15 substantially in the longitudinal direction x of the absorbent article 1, in one or more strands 16 substantially in the transverse direction y of the absorbent article 1 (Figure 3) or in both one or more strands 15 substantially in the longitudinal direction x and in one or more strands 16 substantially in the transverse direction y. Furthermore, the strands 15 substantially in the longitudinal direction and/or the strands 16 substantially in the transverse direction may also each be divided into a series of intermittent areas or zones, or the adhesive 14 may be arranged in any other suitable pattern.

A strand 15 arranged substantially in the longitudinal direction x of the absorbent article 1 can extend over substantially the entire length of the absorbent article 1, or only portions thereof. Likewise, a strand 16 arranged substantially in the transverse direction y of the absorbent article 1 may extend over substantially the entire width of the absorbent article 1, or only portions thereof. The width of a strand 15 can be the same or different from strand 15 to strand of an absorbent article 1, and can also differ from

strand 15 to strand of different absorbent articles 1 on comparison. If an absorbent article 1 comprises more than one strand 15, the distance between the strands 15 can be the same or different when compared between different absorbent articles 1. If an absorbent article 1 comprises more than two strands 15, the distance between two strands 15 may be the same or different for each pair of strands 15. Similarly, the width of a strand 16 can be the same or different from strand 16 to strand of an absorbent article 1, and can also differ from strand 16 to strand of different absorbent articles 1 on comparison. If an absorbent article 1 comprises more than one strand 16, the distance between the strands 16 can be the same or different when compared between different absorbent articles 1. If an absorbent article 1 comprises more than two strands 16, the distance between two strands 16 may be the same or different for each pair of strands 16.

Figure 3 shows a variant of the first embodiment of the absorbent article 1 according to the invention, in which the adhesive 14 is arranged in three strands 16 substantially in the transverse direction y, instead of one strand 15 in the longitudinal direction x. In figure 4 a further variant of the first embodiment of the absorbent article 1 is shown, in which the adhesive 14 is arranged as an entire coating on the liquid-impermeable lower layer 3 instead of in one strand 15 substantially in the longitudinal direction x. One area of the lower surface 13 is shown in Figure 4 without adhesive 14.

As the adhesive capacity of the adhesive 14 according to the invention can be controlled to different levels, the adhesive 14 in different portions of the lower surface 13 of the absorbent article 1 can exhibit different adhesive capacities. In alternative embodiments, the lower surface 13 of the absorbent article 1 comprises at least two areas which are at least partly provided with the adhesive 14, wherein the adhesive capacity of the adhesive 14 differs between at least two of said areas through that the dose of UV-radiation to which the adhesive 14 has been exposed differs between the at least two of said areas. Such an area can be constituted by e.g. a portion of the absorbent article 1 in the longitudinal direction x, a portion of the absorbent article 1 in the transverse direction y, a strand 15 substantially in the longitudinal direction x, a strand 16 substantially in the transverse direction y, or a point.

In alternative embodiments, the absorbent article 1 also has at least one transverse fold line, which substantially extends in the transverse direction y, whereby the absorbent article 1 is intended to be folded along the at least one transverse fold line in its packaged state, so as to minimize the space required for storage and supply of a convenient product. Thereby, the absorbent article 1 is divided into at least two portions

in its longitudinal direction x, substantially defined by the at least one transverse fold line. In alternative embodiments, each of the at least two portions comprises one of the above-mentioned at least two areas. The adhesive 14 thereby exhibits different adhesive capacity in at least two of the portions in which the at least one fold line divides the absorbent article 1.

A second embodiment of the absorbent article 1, shown in Figures 5a, 5b and 5c corresponds to the first embodiment, except that in the second embodiment, the absorbent article 1 has also two transverse fold lines; a first transverse fold line 17 and a second transverse fold line 18,' which extend substantially in the transverse direction y. The absorbent article 1 is hereby intended to be folded along the two transverse fold lines 17, 18 in its packaged state and the absorbent article 1 is divided into a first and a second end portion 19, 20 and a centre portion 21 situated between the end portions 19,

20 in its longitudinal direction x, substantially defined by the two transverse fold lines 17, 18. In the second embodiment, the first and second end portions 19, 20 substantially coincide with the first and second end parts 10, 11, respectively, and the centre portion

21 coincides substantially with the centre part 12. In an alternative embodiment, however, the first and second end portions 19, 20 do not coincide with the first and second end parts 10, 11 respectively, and the centre portion 21 does not coincide with the centre part 12.

Figure 5b shows the second embodiment of the absorbent article 1 after a first fold. The second end portion 20 has thereby been folded along the second transverse fold line 18, in the direction towards the upper layer 2 of the absorbent article, so that the upper layer 2 in the second end portion 20 lies at least partly against the upper layer 2 in the centre portion 21.

Figure 5c shows the second embodiment of the absorbent article 1 after a second, final fold. The first end portion 19 has thereby been folded in along the first transverse fold line 17 in the direction towards the first folded-in second end portion 20, so that the upper layer 2 in the first end portion 19 at least partly lies against the lower layer 3 in the second end portion 20. In such a folded state, the absorbent article 1 can be packed in a packaging wrapper so that a unit packed product is produced. Alternatively, the absorbent article 1 can be placed on a packaging wrapper before the folding, whereby the folding of the absorbent article 1 occurs completely or partly together with the packaging wrapper.

As mentioned above, a number of factors are of importance as to the level of adhesive capacity of the adhesive 14 which is optimal for avoiding the problems with excessively high or excessively low adhesive strength of a given absorbent article 1 to an undergarment as much as possible. However, the optimal level of adhesive capacity of the adhesive 14 to an undergarment can also differ between different portions of an absorbent article 1.

The folding of the absorbent article 1 according to the second embodiment along the two transverse fold lines 17, 18 gives rise to residual stress in the end portions 19, 20, which implies that the end portions 19,20 tend to fall back to (or towards) the positions they had when the absorbent article 1 was folded. To produce a reliable fastening, it is therefore desirable to have a stronger fastening of the end portions 19,20 than of the centre portion 21, i.e. a higher adhesive strength and thereby a higher adhesive capacity of the adhesive 14 in the end portions 19,20 than in the centre portion 21 is desirable.

To compensate for the tendency of the end portions 19,20 to loosen from the undergarment and return to the respective configuration they had when the absorbent article 1 was folded, it is therefore a desirable property that the adhesive 14 exhibits a higher adhesive capacity in the end portions 19,20 of the absorbent article 1 than in the centre portion 21.

In the second embodiment of the absorbent article 1, the adhesive 14 on the surface 13 therefore exhibits a substantially higher adhesive capacity in the end portions 19, 20 than in the centre portion 21, which provides an advantage over traditional absorbent articles in which one usually compromises on adhesive capacity. Such a compromise involves that one has adjusted the adhesive capacity so that the centre portion 21 has obtained an adhesive capacity which is slightly too high and the end portions 19, 20 an adhesive capacity which is slightly too low. The result of such an adjustment is that the fastening of the end portions 19,20 is not completely reliable, while the problem readily occurs that the centre portion 21 sticks too strongly to the undergarment.

As the adhesive 14 according to the invention is a UV-curable adhesive, whose adhesive capacity can be controlled by the dose of UV-radiation which is applied to the adhesive 14 during production of the absorbent article 1, the dose of UV-radiation which has been applied to the adhesive 14 has thus been - controlled in such a way in the second embodiment so as to provide a higher adhesive capacity of the adhesive 14 in the two end portions 19,20 than in the centre portion 21.

Examples of ranges in which the optimal adhesive strength of a "three-folded" absorbent article 1 lies are 2.0-3.0 N/product for the rear and front portions, and 1.5-2.5 N/product for the centre portion, i.e. the optimal adhesive capacity of the adhesive is such that the adhesive strength of the adhesive to an undergarment material lies in the range 2.0-3.0 N/product for the rear and front portions, and 1.5-2.5 N/product for the centre portion.

In a variant of the second embodiment of the absorbent article 1, the adhesive capacity of the adhesive 14 of the two end portions 19,20 is essentially the same. In a further variant of the second embodiment of the absorbent article 1, the adhesive capacity of the adhesive 14 in the first end portion 19 is higher than the adhesive capacity of the adhesive 14 in the second end portion 20, while in yet another variant of the second embodiment, the adhesive capacity of the adhesive 14 in the second end portion 20 is higher than the adhesive capacity of the adhesive 14 in the first end portion 19.

Figure 6 shows a third embodiment of the absorbent article 1, which corresponds to the first embodiment, except that, in the third embodiment, the absorbent article 1 comprises further at least one fastening flap 22, also called "wing", at each side edge 8,9. Each fastening flap 22 is intended to be folded around an edge of a leg-opening of a user's undergarment, towards the outside of the undergarment. A fastening flap 22 is designed in any known way, and comprises the upper and lower layers 2,3. Furthermore, each of the fastening flaps 22 are provided with adhesive 14 on at least a part of a surface 23 which is intended to face the user's undergarment, whereby the fastening flaps 22 are intended to be fastened to the outside of a user's undergarment by means of the adhesive 14 on the surface 23. The fastening flaps 22 help to securely position the absorbent article 1 in the undergarment of a user, as well as to reduce the risk of leakage via the side edges. The adhesive capacity of the adhesive 14 which is applied to the fastening flaps 22 can vary from the adhesive capacity which is required of the adhesive 14 in the other parts of the absorbent article 1, in order to obtain optimal placement of the absorbent article 1.

As the adhesive 14 according to the invention is a UV-curable adhesive, whose adhesive capacity can be controlled by the dose of UV-radiation which is applied to the adhesive 14, the adhesive capacity of the adhesive .14 on the surface 23.can be controlled during the curing (hardening) by means of the dose of UV-radiation to which it is exposed. In a variant of the third embodiment, the adhesive 14 on the surface 23 of each fastening flap 22 exhibits an adhesive capacity which is substantially different from the adhesive capacity of the adhesive 14 on said lower surface 13 of the liquid-impermeable lower layer 3. In a further variant of the third embodiment, the adhesive 14 on the surface 23

of each fastening flap 22 exhibits an adhesive capacity which is substantially the same as the adhesive capacity of the adhesive 14 on said lower surface 13 of the liquid- impermeable lower layer 3.

An example of the range in which the optimal adhesive strength lies for the fastening flaps 22 is 1.5 - 3.0 N/product, i.e. the optimal adhesive capacity of the adhesive 14 is such that the adhesive strength of the adhesive 14 of the fastening flaps 22 to an undergarment material lies in the range 1.5 - 3.0 N/product.

A fourth embodiment of the absorbent article 1 (not shown) is a combination of the second embodiment shown in Figures 5a, 5b and 5c, and the third embodiment shown in Figure 6. According to the fourth embodiment, the absorbent article 1 thus has two transverse fold lines 17, 18, whereby the absorbent article 1 is divided into a first and a second end portion 19,20, as well as a centre portion 21 which is located between the end portions 19,20, and comprises at least one fastening flap 22 at each side edge 8,9. In a variant of the fourth embodiment, the adhesive 14 on the surface 23 of each fastening flap 22 exhibits an adhesive capacity which is different from the adhesive capacity of the adhesive 14 in all of the first and second end portions 19,20 and the centre portion 21. In a further variant of the fourth embodiment, the adhesive 14 on the surface 23 of each fastening flap 22 exhibits an adhesive capacity which is substantially the same as the adhesive capacity of the adhesive 14 in at least one of the first and second end portions 19,20 and the centre portion 21.

A fifth embodiment of the absorbent article 1 (not shown) corresponds to any of the previously mentioned embodiments, except that at least one protective layer is further arranged over the adhesive 14, which protective layer has at least one surface which has been treated with a release substance and which lies detachably against the adhesive 14. The protective layer is formed from e.g. paper or similar which has been treated with a release substance, and is intended to function as protection against the adhesive 14 becoming dirty or undesirably adhering to other objects during transport and storage. Furthermore, the protective layer is intended to prevent the adhesive 14 from drying out before use. In a variant of the fifth embodiment, in which the absorbent article 1 has fastening flaps 22, the absorbent article 1 comprises a protective layer which covers the adhesive 14 at both the lower surface 13 of the liquid-impermeable lower layer 3 and the adhesive 14 of the surfaces 23 of the fastening flaps 22. In another variant of the fifth embodiment, in which the absorbent article 1 has fastening flaps 22, the absorbent article 1 comprises a protective layer for the adhesive 14 on the lower surface 13 and a protective layer for each of the surfaces 23 of the fastening flaps 22. In other variants of

the fifth embodiment, the at least one protective layer is constituted by a packaging wrapper, which, as well as being a protective layer, is intended to be a package in which the absorbent article 1 is packed.

The packaging wrapper can, for example, be a sheet of e.g. paper, plastic or another flexible material, which has been treated with a release substance in order to provide a removable attachment. Such a treatment with a release substance usually comprises a silicone coating. The release substance treatment can be applied over the entire surface of the packaging wrapper which faces the absorbent article 1, or be selectively applied only within those areas which lie against the adhesive 14 of the absorbent article 1.

Examples

A test was carried out to demonstrate that the adhesive capacity of an adhesive 14 of an absorbent article 1 according to the invention can be controlled to desired levels during production of the absorbent article 1.

One of the above-mentioned preferred adhesives was used in the test: Sanicare UV 4101 (may be obtained from Henkel KgaA, Dϋsseldorf, Germany), which is a pressure- sensitive UV-curable hot melt adhesive with an adhesive capacity which depends on the dose of UV-radiation to which it is exposed. Sanicare UV 4101 cures upon irradiation with UVC-light (light with wavelength between 200 and 280 nm) and its adhesive capacity is thereby not affected by sunlight, as this consists of UVB-light (light with wavelength between 280 and 320 nm) and UVA-light (light with wavelength between 320 and 400 nm). The adhesive capacity of Sanicare UV 4101 is not affected by ageing and therefore exhibits a stable adhesive capacity over time. Furthermore, Sanicare UV 4101 is solvent-free, has a viscosity in the uncured state of 33000 ± 10000 mPa.s at 140° C, shows no irritation according to OECD-404 and ISO EN 10993-5 and provides a transparent, colourless adhesive film.

In a first test, Sanicare UV 4101 was applied to a polyethene film (PE-film) with the name Mel 148 (may be obtained from Trioplanex International AB; Landskrona, Sweden). Application of the adhesive was carried out in the same way as is usually carried out for corresponding application during production of absorbent articles such as e.g. sanitary napkins. A paper strip (Loparex ESP 43 from Loparex Oy, Finland) treated with a release substance was coated with a continuous strand of the adhesive, whereupon the adhesive was transferred to the PE-film. Coating and transferring were carried out immediately after one another in a continuous operation. Application was carried out at a temperature of 150° C. The strand had a width of 30 mm and a coat weight of 24.7

g/m ² . After 30 minutes storage at room temperature, the continuous material web comprising the release substance coated paper strip, glue strand and PE-film was cut into discrete lengths. The paper strip was removed, and UV-curing of the test samples was subsequently carried out in a separate process.

The adhesive was UV-cured on a total of 10 samples, of which half were cured with a UV- radiation dose of 27 mJ/m ² , and the other half were cured with a UV-radiation dose of 9 mJ/m ² . Irradiation was carried out with a standard mercury lamp (Fusion F 600) with an intensity of 30 mW/cm ² and with UV-light with a wavelength of 250 nm (UVC-light). The samples were loaded onto a transport web with the adhesive oriented away from the material web. The transport web with the samples passed the mercury lamp, whereby the UV-radiation was set by adjusting the speed of the material web. At a web speed of 50 m/min, the dose of UV-radiation was 9 mJ/m ² and at a web speed of 30 m/min, the dose was 27 mJ/m ² .

The adhesive strength on cotton cloth for the 10 samples was then measured. Measurement of the adhesive strength was carried out on cotton cloth no. 460 from Test Fabrics (previously Cromocol), USA. Measurements were carried out one week after UV- curing had taken place, but as the adhesive does not change after curing, the measurements could well have taken place earlier. The cotton cloth, which is identical on both sides, was applied to the adhesive on the samples, after which a controlled compression was carried out via a roller with a hard rubber surface weighing 2 kilos and having a width of 50 mm. The roller was passed twice (over and back) over the cotton cloth and the sample comprising the surface with adhesive, at a speed of 1500 mm/min. One minute after the compression was complete, the sample was placed in a tensile tester (Instron 4301) to determine the adhesive strength between the cotton cloth and the PE-film comprising the adhesive. The tensile test was carried out in the longitudinal direction of the adhesive strand, and measures the average force when a peel force perpendicular to the adhesive joint is applied to the sample, which gradually opens the joint. The sample is inserted into the tensile tester, with a flap of the cotton cloth fastened in one fastening clamp of the tensile tester and a flap of the PE-film in the other fastening clamp of the tensile tester so that the material layers gradually are separated in the longitudinal direction of the adhesive joint during the tensile test. During the tensile test, the portions of the PE-film and the cotton cloth which are not yet separated from one another should be held substantially perpendicular to the pull-direction of the tensile tester. A computer program with the settings: clamping length 50 mm, pull- speed 500 mm/min and pull-length 140 mm was used in the tensile tester. The computer program also calculates the average force for the current tensile test.

The following results were obtained in the first test, with application of Sanicare UV 4101 on the PE-film:

In a second test, Sanicare UV 4101 was applied to a SMMS-layer (spunbond-meltblown- meltblown-spunbond-layer) from Corovin GmbH, Peine, Germany, with the basis weight of 30 g/m ² . The second test was carried out in the same way as the first test, except that the PE-film was exchanged for the above-mentioned SMMS-layer.

The following results were obtained in the second test, with application of Sanicare UV 4101 on the SMMS-layer:

As the results show, different initial adhesive strengths were obtained upon application of various doses of UV-radiation to the adhesive in both tests. A low dose of UV-radiation gave a higher initial adhesive strength than a high dose of UV-radiation.

As the adhesive was coated with the same amount per unit area on all samples in these tests, a substantially uniform curing upon UV-radiation with the two respective doses should have been obtained, and the adhesive strength does not therefore depend on deviations in the curing. The results for the two different doses of UV-radiation can thus be directly compared, and the differences in adhesive strength are due to the two different doses of UV-radiation giving rise to different adhesive capacities.

As mentioned above, the adhesive strength of an adhesive to a given material depends completely on the adhesive capacity (tackiness) of the adhesive, so that the measure of the adhesive strength is an indirect measure of the adhesive capacity. The results obtained in this test can thereby also be expressed as that a low dose of UV-radiation gave a higher initial adhesive capacity (tackiness) of the adhesive than a high dose of UV-radiation.

After removal of the PE-film and the SMMS-film, respectively, from the cotton cloth, there were no visible residues of adhesive or parts of the PE-film and the SMMS-film, respectively, left on the cotton cloth in any of the samples.

Through this example, it has thus been demonstrated that the adhesive capacity of a UV- curable adhesive, the adhesive capacity of which depends on the dose of UV-radiation to which it has been exposed, can be controlled during production to desired levels through application of different doses of UV-radiation.

Fundamental new features of the invention as applied to a preferred embodiment thereof have been shown and described and pointed out herein, although it should be understood that different omissions and replacements and amendments in the form and details of the illustrated articles, and in their use, can be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which carry out essentially the same function in essentially the same way to obtain the same result fall within the scope of the invention. Furthermore, it should be understood that structures and/or elements and/or method steps which are shown and/or described in connection with a disclosed form or embodiment of the invention may be incorporated in any other form or embodiment which is shown, - described or indicated, as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

For example, the absorbent article can cpmprise other UV-curable ^dhesives, than those given above. Furthermore, the number of fold lines can differ from the numbers given, the number of strands of adhesive can differ from those numbers given, or the adhesive may be applied in a pattern other than those given. Furthermore, the optimal values of adhesive capacity can vary from those which are given.