ABSORBENT ARTICLE COMPONENT

Abstract

A non-woven functional core cover for use in combination with an absorbent core, where said functional core cover comprises at least a first fraction comprising lyocell fibres, and characterised in that a majority of said fibres are oriented in the same direction. Thus, the absorbent core cover may be considered an absorbent article component. Thereby, a functional core cover having improved wicking properties and improved wet integrity is realised, the advantages allowing reducing the amount of fluff used in the mix with SAP. A reduction of material used in the absorbent core improves the feeling of wearing the absorbent product, e.g. a baby diaper, which in turn facilitate the movement of the baby. The wicking properties cause liquid to be distributed better across the surface of the core cover, such that more of the absorbent core is exposed to the expelled liquid.

Claims

1. An absorbent article comprising a non-woven functional core cover encapsulating an absorbent core, said functional core cover comprising at least a first fraction comprising lyocell fibres, where a majority of the fibres constituting the functional core cover are oriented in the same direction, wherein the fibres in said functional core cover are mutually bonded via entanglement.

2. The absorbent article according to claim 1, wherein said functional core cover further comprises a second fraction comprising viscose rayon fibres.

3. The absorbent article according to claim 1, wherein the non-woven core cover is made in a hydroentanglement process.

4. The absorbent article according to claim 1, wherein a majority of the fibres of said functional core cover are oriented in the machine direction of the functional core cover, the machine direction being the direction in which a precursor to the functional core cover flows into a hydroentanglement section for bonding in the hydroentanglement process.

5. The absorbent article according to claim 1, wherein said functional core cover is flat, patterned, or apertured.

6. The absorbent article according to claim 1, wherein said functional core cover further comprises a third fraction comprising one or both of polypropylene fibres or polyester fibres.

7. The absorbent article according to claim 1, wherein the basis weight of said functional core cover is between 15 gsm and 30 gsm.

8. The absorbent article according to claim 1, wherein the density of the fibres of the non-woven functional core cover is between 1 dtex and 3.3 dtex.

9. The absorbent article according to claim 1, wherein the fibre length in the non-woven functional core cover is between 20 mm and 60 mm, or more specifically between 35 mm and 45 mm.

10. A method of making an absorbent article according to claim 1, comprising at least the steps of making a functional core cover by: selecting a fraction of lyocell fibres, preparing a fibrous web of said selected fibres, and moving said fibrous web into a hydroentanglement section, whereby the fibres become mutually bonded in a non-woven fabric, and a majority of the fibres become oriented in the same direction, and encapsulating an absorbent core with said functional core cover.

11. The absorbent article according to claim 1, wherein the absorbent article is a diaper encapsulating an absorbent core covered by a functional core cover.

Description

SHORT LIST OF THE DRAWINGS

[0060] In the following, example embodiments are described according to the invention, where

[0061] FIG. 1 illustrates a diaper suitable for being used in combination with a functional core cover according to the invention,

[0062] FIG. 2 illustrates the process of liquid wicking in a functional core cover according to the invention.

[0063] FIG. 3 illustrates a possible fabrication method for making a functional core cover according to the invention.

[0064] FIG. 4 illustrates the concept of wicking in prior art and in a functional core cover according to the invention.

DETAILED DESCRIPTION OF DRAWINGS

[0065] In the following, the invention is described in detail through embodiments thereof that should not be thought of as limiting to the scope of the invention.

[0066] FIG. 1 illustrates a diaper 10 suitable for use in combination with a functional core cover 100 according to the invention. It should be noted that the figure is included for illustrative purposes only and does not explicitly disclose features of the functional core cover 100 as such. Further, it should be noted that the use of the functional core cover 100 is not limited to diapers only, but that said functional core cover 100 may be used in other products as well, for example in hygiene towels, bandages, or wipes. However, in a diaper as illustrated, the machine direction MD of the functional core cover 100 is preferably oriented, such that it extends from a front side 11 to a reverse side 12 of the diaper 10. Consequently, the cross direction CD extends from a first leg opening 1 to a second leg opening 2. In the diaper 10 as illustrated, the leg openings 1, 2 are open since the diaper 10 is open, i.e. the ears of the reverse side 12 are not fastened on the front side 11. The machine direction MD and the cross direction CD are included for reference, but refer to the functional core cover 100 only since other parts of the diaper 100 may comprise fabric of different types. The line A-B indicates a series of side views discussed in relation to FIG. 2.

[0067] The functional core cover 100 encapsulates an absorbent core (not shown explicitly) suitable for absorbing expelled liquid (not shown). Preferably, the absorbent core is arranged in a bottom part 13 of the diaper 10, the bottom part 13 extending between the front side 11 and the reverse side 12. Preferably, the absorbent core is substantially flat and flexible, such that it may adjust to the shape of the diaper and the movements and contours of the wearer. The functional core cover 100 may be arranged below a cushioning layer (not shown). The cushioning layer may be omitted by the functional core cover 100 in certain embodiments of the invention, whereby the diaper may be made lighter and more flexible. The functional core cover 100 may in itself function as a cushioning layer thus having a dual function.

[0068] FIG. 2 illustrates a series of side views of a diaper taken along the line A-B in FIG. 1. References to A and B are included in FIG. 2 for illustrating the orientation of the side view. Despite again referring to a diaper, the skilled person notes that the invention relates to the functional core cover as such. In other words, the skilled person acknowledges that a functional core cover according to the invention may be utilised in other absorbent products, especially products used in the health care industry or in hygiene.

[0069] The series of side views illustrate the process of liquid absorption, and how a functional core cover according to the invention improves the utilisation of the absorbent core. The side views are taken from a diaper comprising a cushioning layer 14, but as it was mentioned above, the functional core cover itself may provide sufficient cushioning thereby removing the need for further layers. Preferably, the cushioning layer 14 is oriented adjacent the skin 3 of the wearer. The functional core cover 100 is shown as a box covering/encapsulating the absorbent core 110. The absorbent core 110 is illustrated using a plurality of dots 111 for highlighting a preferred embodiment wherein the absorbent core 110 comprises granules of SAP. It should be noted that the absorbent core 110 may further comprise cellulosic fluff pulp (not shown) functioning as a carrier for the SAP and for providing further cushioning and absorbency. A droplet 20 is included for illustrating how liquid is wicked and absorbed by the functional core cover 100 and the absorbent core 110 in combination. A back sheet 15 shields the diaper from the environment 4.

[0070] In FIG. 2a, a droplet 20 is expelled onto the diaper. The displaced position P relative to an origin O of the absorbent core 110 illustrates a common situation in a diaper, wherein liquid is expelled either in the front or in the back by human physiology. Thus, this helps illustrating the obstacles in prior art.

[0071] In FIG. 2b, the droplet 20 has been partly absorbed by the absorbent core 110. This is illustrated by enlarged dots (saturated SAP) 112 in the vicinity of the droplet 20. This resembles the situation and problems in prior art: the absorption occurs in the vicinity of the liquid expelling (the droplet 20), whereas a large portion of the absorbent core 110 remains dry. It is an aspect of the invention to provide means for wicking liquid towards the dry portions of the absorbent core 110 in order to utilise the full potential of said absorbent core 110, and especially the SAP.

[0072] According to the present invention, the situation shown in FIG. 2b merely represents an intermediate step, wherein the preliminary absorption occurs. During this intermediate step, liquid is partly absorbed by the absorbent core 110, especially by the SAP, whereas a remaining part of the liquid is absorbed by the functional core cover 100. Thereby, the liquid is absorbed by any kind of medium, rather than overflowing the absorbent core 110, i.e. no liquid remains unabsorbed until SAP of the absorbent core 110 becomes active. Concurrently, the liquid absorbed by the functional core cover 100 is wicked away from the point of depletion 21, i.e. the local area where liquid is expelled. The wicking 22 is illustrated by a set of arrows pointing in opposite directions away from the point of depletion 21.

[0073] In FIG. 2c, the liquid wicked by the functional core cover 100 has been wicked towards all parts of the absorbent core 110. The skilled person would understand that this is a gradual process, where the absorbent core/SAP gradually absorbs liquid until it has been saturated. When saturated, liquid is wicked further away towards unsaturated SAP, and so on. Further, the skilled person would understand that the liquid initially absorbed by the functional core cover 100 is eventually absorbed by the absorbent core 110, such that said absorbent core 110 holds the majority of the liquid, but that the functional core cover 100 functions as an intermediate absorption medium. As illustrated by FIG. 2c, the absorbent core 110 has absorbed the entire droplet, despite said droplet being arranged in a displaced position P relative to an origin O of the absorbent core 110. In prior art, this would not be the case following a single expelling of liquid.

[0074] FIG. 3 illustrates the process of making a functional core cover 100 according to the invention. FIG. 3a illustrates a side view of the process, whereas FIG. 3b illustrates a top view of the embodiment shown in FIG. 3a.

[0075] At least one carding machine 50 is provided with the selected fibres, i.e. at least a fraction comprising lyocell fibres L. The carding machine 50 lays a fibrous web 51 comprising the fibres according to the invention on a conveyor belt 52, said conveyor belt 52 moving the fibrous web 51 into a hydroentanglement section 53. The direction of the conveyor belt 52 is indicated by the arrow 59. The hydroentanglement section 53 applies a plurality of water jets 54 onto the fibrous web 51, whereby the fibres within said fibrous web 51 are bonded/entangled. The end product of the process is a non-woven functional core cover 100 according to the invention which is bonded using hydroentanglement.

[0076] It should be understood, that the above-disclosed process of making a functional core cover according to the invention is not limiting to the scope of the invention.

[0077] When making the functional core cover 100 according to the above-described process, a majority of the fibres are oriented primarily in the machine direction MD, i.e. the direction identical to the orientation of the conveyor belt 52 carrying the fibrous web 51 into the hydroentanglement section 53 and the direction in which the fibrous web flows into the hydroentanglement section 53. This resulting orientation of the fibres in the functional core cover 100 may be utilised in the implementation of said functional core cover 100 in a diaper as described above. More precisely, if the functional core cover 100 is oriented in the diaper such that the machine direction MD is parallel to the direction extending from a front side to a reverse side of said diaper, wicking is enhanced, since liquid wicks along the length of fibres more easily than across fibres. The combination of fibre densities and lengths may further ensure that a majority of the fibres become oriented in the same direction. The corresponding cross direction CD being perpendicular to the machine direction MD is included for reference.

[0078] FIG. 4 illustrates the concept of wicking in a prior art core cover 90 (FIG. 4a) compared to wicking in a functional core cover 100 (FIG. 4b) according to the invention from a top view perspective. The machine direction MD and the cross direction CD have been included for reference. The rectangle illustrates a common shape of a prior art core cover 90 and a functional core cover 100 when used in an absorbent product, e.g. a diaper, where the shape ensures a broad coverage of the body. A liquid depletion 200 is shown to have its centre displaced from the centre of the rectangle, such that the need for enhanced wicking properties is highlighted. In prior art 90 (FIG. 4a), the liquid depletion is seen to form concentric circles 210, where the increase of the radii of the circles illustrates how the liquid is distributed in time. After a while, part of the liquid will reach the edge 91 of the rectangle (core cover) which illustrates a leakage situation. However, once said part of the liquid has reached the edge 91, a large part of the rectangle (i.e. core cover) remains dryespecially the bottom half of the illustration in FIG. 4a. On the other hand, in a functional core cover 100 (FIG. 4b) according to the invention, the wicking properties ensure that the liquid has a tendency to wick in the machine direction MD, i.e. the direction in which the fibres are oriented in the functional core cover 100. This is illustrated by the concentric ellipses 220. This reduces the risk of leakage while at the same time ensures that the liquid is distributed further away from the point of depletion. When distributed further away, more SAP may absorb the liquid, i.e. the functional core cover 100 provides a way to utilise the SAP present in the absorbent core (not shown) encapsulated/covered by the functional core cover to a greater extent than known from prior art.

[0079] FIG. 4c illustrates a zoom Z of a part of the functional core cover 100 according to the invention. In the zoom Z, part of the fibres 101 constituting the functional core cover 100 are shown. The orientation of the fibres 101 is particularly illustrated: although being flexible, i.e. bending in the illustration, the main orientation of the fibres is identical to a majority of the fibres. This common orientation is preferably aligned with the machine direction MD of the fabric, but may in general be any direction and may thus for example be independent from the manufacturing technique. The orientation may be expressed in terms of the tensile strength of the fabric, where said tensile strength is greater in the machine direction MD (or any direction in which a majority of the fibres are oriented) than in the cross direction CD (the direction perpendicular to the direction in which a majority of the fibres are oriented).

REFERENCE NUMBERS

[0080] A Point A in cut A-B [0081] B Point B in cut A-B [0082] CD Cross Direction [0083] L Lyocell fibres [0084] MD Machine Direction [0085] O Origin [0086] P Displaced position [0087] Z Zoom [0088] 1 First leg opening [0089] 2 Second leg opening [0090] 3 Skin [0091] 4 Environment [0092] 10 Diaper [0093] 11 Front side [0094] 12 Reverse side [0095] 13 Bottom part [0096] 14 Cushioning layer [0097] 15 Back sheet [0098] 20 Droplet [0099] 21 Point of depletion [0100] 22 Wicking direction [0101] 50 Card [0102] 51 Fibrous web [0103] 52 Conveyor belt [0104] 53 Hydroentanglement section [0105] 54 Water jets [0106] 59 Moving direction of conveyor belt 52 [0107] 90 Prior art core cover [0108] 91 Edge of prior art core cover 90 [0109] 100 Functional core cover [0110] 101 Fibres of functional core cover 100 [0111] 110 Absorbent core [0112] 111 Super Absorbent Polymer (SAP) [0113] 112 Saturated SAP [0114] 200 Liquid depletion [0115] 210 Concentric circles [0116] 220 Concentric ellipses