FR2848815A1 - Disposible nappy, contains relatively short absorbent core with restricted absorption index - Google Patents

Abstract

The absorbent core (10) has a restricted absorption index and a specific low thickness and/or length. A disposible nappy (1) comprises a back sheet (20) with a length (A) and a front sheet and an absorbent core with a length (B), the back sheet comprising two end regions and a central region. The absorbent core is positioned on top of the central region of the back sheet, but not on top of either of the end regions. The absorbent core has an absorption index C/A of less than 0.75, where C is the total absorption capacity of the core. The average thickness of the core is less than 6 mm and/or the ratio B/A is less than 0.8. An Independent claim is also included for a combination of the above nappy with a second nappy comprising a back sheet with a length (A) and a top sheet and an absorbent core with a length (B), the B/A ratio being 0.8 or more, where the second nappy is intended for use after the above (first) nappy.

Description

FIELD OF THE INVENTION

  This invention relates to diapers and training pants, having a short absorbent core and a specific absorbency depending on the size of the backsheet.

  FOUNDATION OF THE INVENTION It is generally known that there is a need for disposable diapers which provide the wearer with more comfort, while still absorbing well. zo As a result, we designed, for example, diapers with elasticated waist bands, more comfortable crotch elastics, etc. These characteristics are particularly important for the wearer when he is moving a lot, that is to say during the day.

  Most of these features are expensive and, in addition, increase the complexity of the product manufacturing process. For example, production lines have to handle many more components which differ from one product size to another.

  It has been found that a limited absorption capacity is only necessary during the daytime use of a diaper, since the diapers are very often changed. We have now found that a more comfortable diaper is obtained if the core is shortened It has been found that certain layers with a short core and a certain index of absorption capacity will satisfy the above requirements.

  Also, a logistically simple way of making these layers has been found, namely by combining an absorbent core of a smaller layer (as normally produced) and a back sheet and a topsheet (and optionally of other elements) of a larger layer (as normally produced) This results in a logistically very simplified production, since one does not have to use new elements, but only to combine them differently. As a result, a comfortable day layer is obtained, which is easy to manufacture, with sufficient absorption capacity.

2 FR 0216413 le 18 04 2003

SUMMARY OF THE INVENTION

  In a first embodiment, the invention provides a disposable diaper comprising a back sheet having a longitudinal axis of length A, a top sheet and an absorbent core having a longitudinal axis of length B, the back sheet having a first end region and a second terminal region, positioned towards each of the two ends of the longitudinal axis, and between which is a central region, the absorbent core being superimposed on the central region of the backsheet, but not on the first and second regions terminals, and the absorbent core has a total absorption capacity C, characterized in that the absorbent core has an absorption index C / A of less than 0.75, typically greater than 0.40, the absorbent core has an average thickness of less than 6.0 mm, and / or the ratio of B to A is less than 0.8.

  The invention also relates to a combination of a first layer, according to the invention, as defined above, and a second layer with a back sheet having a longitudinal axis of length A, a surface sheet and an absorbent core with a longitudinal axis of length B, in which the ratio of B to A is 0.8 or more, intended to be used successively Typically, the first layer will be used during the day, while the second layer will be used at night.

BRIEF DESCRIPTION OF THE DRAWING

  Figure 1 is a top view in section of a preferred layer according to the invention.

  DETAILED DESCRIPTION OF THE INVENTION As used herein, the following terms have the following meanings: "Longitudinal" means a direction parallel to the maximum linear dimension, typically the longitudinal axis, of the article and includes directions in a angle of 45 with respect to the longitudinal direction 35 "Length" of the article or of a component thereof as used herein, generally refers to the size / distance of the maximum linear dimension or typically to the size / distance of the longitudinal axis, of an article or part of it.

  The "lateral" or "transverse" direction is orthogonal to the longitudinal direction, for example, in the same plane as the majority of the article and the longitudinal axis, and the transverse direction is parallel to the transverse axis. "Width" of the article or of a component thereof as used herein, refers to the size / distance of the orthogonal dimension from the longitudinal direction of the article or of its component , for example orthogonal to the length of the article or component thereof, and typically refers to the distance / size of the dimension parallel to the transverse axis of the article or component.

  The "Direction-Z" is orthogonal to both the longitudinal and transverse directions, for example parallel to the minimum linear dimension of the article. The "thickness>" or "height" of the article or of a component thereof, as used herein, denotes the size / distance of the dimension in the 2 o direction-Z.

  As used herein, the term "attached" encompasses configurations in which one member is directly attached to another member by attaching the member directly to the other member.

  The invention applies equally to diapers as to donning or training pants. Thus, although the invention is described in detail with reference to a diaper (for babies, children or adults), this description applies also in disposable absorbent pants.

  The portable, disposable absorbent article, for example a diaper, according to the invention has a back sheet, which is typically impermeable to liquids.

  This article can have the property of breathing, and in this it is permeable to air or even to humidity vapor In a preferred embodiment, the article does not have the property to breathe We can use here all materials known to be suitable as a backsheet.

  The back sheet, or any portion thereof, may be elastically expandable in one or more directions.

  Preferably, the back sheet is colored; preferably the back sheet is for this, or in addition, provided with colored printed patterns. s This can be done on the outer face of the back sheet or, if the back sheet is transparent, the affixing can be done on the inner face, or if the back sheet is a multilayer sheet, the affixing can be done on only one of the layers of the multi-layer sheet This can be beneficial to mask any body exudate received in the layer during use, so that the user or caregiver cannot see body exudates from the outside.

  Also, an absorbent core is present, which is placed between a portion of the top sheet and the back sheet.

  The absorbent core may include any absorbent material which is generally compressible, conformable, non-irritating to the wearer's skin, capable of absorbing and retaining liquids, such as urine and other body exudates, such as fragmented wood pulp, crêped cellulose pads; blown melt polymers, including blends of blown melt polymers and blown melt polymer layer laminates (or mixtures thereof); chemically stiffened, modified or crosslinked cellulosic fibers; fabrics, including fabric wraps and fabric laminates; absorbent foams; absorbent sponges; superabsorbent polymers; absorbent gelling materials; or any other known absorbent material, or combinations thereof. Examples of absorbent structures usable as absorbent webs are described in US Patents 4,610,678; US 4,673,402; US 4,834,735; US 4,888,231 US 5,137,537; US 5,260,345; US 5,387,207 and US 5,625,222.

  The absorbent core may comprise more than one layer of absorbent material. In a preferred embodiment, it comprises a single layer of absorbent material.

  The absorbent core preferably comprises (super) absorbent gelling polymers.

  In a preferred embodiment, the single layer or one of the layers of the absorbent core comprises pulp fibers and absorbent gelling polymers, as is known in the art. Preferably still, the absorbent core comprises approximately 40 to 70%. or even 50 to 65% by weight (of the absorbent core) of absorbent gelling materials and 30 to 60% or even 50 to 35% by weight of pulp fibers.

  s In another embodiment, the absorbent core may preferably only comprise less than 15% by weight of pulp fibers; preferably, the core is free of fibers. It may then be preferable for the core to comprise only a layer which comprises only absorbent gelling polymers.

  The absorbent core has an absorption index C / A of less than 0.75%, preferably less than 0.73 or even less than 0.70 or even less than 0.65 Preferably, the index of absorption C / A is greater than 0.35 or even greater than 0.45 or even greater than 0.50.

  The core typically has an average thickness of less than 7.0 mm 15 or even less than 6.5 mm or even less than 6.0 mm.

  The ratio of the length B of the longitudinal axis of the core (which is typically the length of the core) and the length A of the longitudinal axis of the back sheet (which is typically the length of the back sheet) is less than 0.8, preferably less than 0.78 or even less than 0.75 or even less than 0.70 or even less than 0.65 Preferably, the B / A ratio is greater than 0, 50 or even greater than 0.55.

  A particularly preferred disposable diaper has a length A of the backsheet of 47 cm to 60 cm, and a length B of the core of 30 cm to cm, so that the ratio of B to A is as described above .

  The part of the backsheet which is not in contact with the absorbent core has a length D (measured along the longitudinal axis of the backsheet) in the back belt region and a length E in the region of front belt The length D is therefore typically the length from the rear edge of the core to the rear edge of the belt In the particular embodiment of the above paragraph, this length is at least 5 cm, better at least minus 5.5 cm, and better still at least 6 cm.

  Preferably the core is off-center, i.e. such that the length D is greater than the length E Preferably, D is at least 1.5 times greater than E, better still at least twice bigger.

  By comparison, Pampers size 4 diapers, currently on the market in Europe, produced by The Procter & Gamble Company, have a back sheet with a length of 50 cm, and a central core with a length of 45 cm; Huggies diapers size 4, commonly found on the 5th market in Europe, produced by Kimberly Clark Worldwide Inc, have a back sheet with a length of around 45 cm and a central core with a length of around 34 cm.

  The article, for example a diaper according to the invention, may have side panels, and / or preferably one or more crotch barriers, which provide improved containment of liquids and other bodily exudates, as described in the patents US 3,860,003; US 4,808,178; US 4,695,278 and US 4,795,454.

  The diaper typically has a first waist region or front waist region, a second waist region or rear waist region, opposite the first waist region, and a central region, located between the first waist region and the second belt region The belt region, or preferably the belt band typically comprises the line of force of the layer Typically, the belt regions of the layer have a part, which is or forms the belt band In a type diaper, the belt band is open before use and must be fastened around the wearer's hips For this purpose, the diaper preferably has a fastening system, typically joined to the region or belt strip The fastening system comprises preferably adhesive tabs and / or hook and loop fastening tabs, although any other known means of fastening is generally acceptable. The fixing system is described in US Patents 3,848,594; US 4,662,875; US 4,846,815; US 4,894,060; US 4,946,527; US 5,151,092; US 5,221,274 and US 4,963,140 The belt regions can include an elastic belt feature. Such an elastic belt feature can be achieved in many different ways, including those described in US Patents 4,515,595; US 5,151,092.

  The top sheet of the article of the invention is air permeable and liquid permeable. The top sheet is preferably very thin, soft and flexible; it preferably has a very low base weight, preferably less than 35 g / m 2 or even less than 30 g / m 2 or even even less than 25 g / m 2 The top sheet can be made of any material or material multilayer It preferably comprises fibers of polyethylene, polypropylene and / or polybutylene, or (a mixture) fibers of copolymers of polyethylene, polypropylene and / or polybutylene Preferably, the fibers are fibers of polypropylene.

  The layer of the present invention can be manufactured by known methods. Preferably, the absorbent core is that of a layer o as sold on the market, of smaller size than the other elements of the layer, in particular the sheet. rear, provided that the required absorption capacity is obtained However, it is also recommended that the core be of reduced thickness, compared to existing layers For example, this can be obtained by incorporating into the core less than layers than is commonly done, for example a single layer of absorbent material.

  Figure 1 is a schematic top view in section, of the layer (1) of the invention in the stretched state The absorbent core (10) is placed in the central region of the back sheet (20), so the rear belt region (41) is not covered by the absorbent core (10) The cut is made along the surface formed by the longitudinal axis (Y) and the transverse axis (X), just above the absorbent core (10) and below the upper sheet (which is not shown here).

  The indicated lengths A and B are as described above. 25 The length D is the dimension, along the longitudinal axis (Y) of the back sheet (20), of the portion of this back sheet (20) which is not in direct contact with the absorbent core in the rear waist region (41); the length E is the dimension, along the longitudinal axis (Y) of the back sheet (20), of the part of the back sheet (20) which is not in contact with the absorbent core (10 ) in the front waist region (40).

  Figure 1 shows the curvature of the leg openings (30, 31), which can have any shape and dimension, and which preferably each have one or more leg elastic (crotch barriers). The layer of Figure 1 has an absorbent core (10) which consists of a single absorbent layer, comprising absorbent gelling polymers, enclosed in a liquid permeable sheet, so as to ensure the retention of the polymers The first layer may, in addition, include pulp (for example fibers).

  The layer (1) as shown does not have any characteristic of elasticated waistbands, however, such elasticized waistbands are preferably present, preferably attached to the terminal edges of the front waistband region io (40) and of the rear waistband region (41).

  The diaper (1) proves to be quite suitable as a comfortable diaper for baby, intended to be used during the day. A commercially available diaper as described above can then be used during the night, to provide more absorption, but less comfort 15 (during major movements) overnight.

  Test methods referred to here: Absorption capacity (C): The absorption capacity of the core of a layer according to the invention can be determined by the centrifugal capacity test of the sachet tea as described in published PCT application WO 98/43578, with the following modifications and / or improvements For the purposes of this invention, the absorbent core or typically the entire layer, is encapsulated in the material of a sachet of tea, leaving enough 25 "pout" to provide enough volume for the soul or the layer soaked in fluids and allow it to swell without constraint If we test a soul that has an impermeable layer on one side or a layer with a back sheet, then orient the impermeable layer or the back sheet in the centrifuge in the direction of the axis of rotation with the other parts of the core or the layer (for example the absorbent material) facing radially outwards from the waterproof material (if both sides of the core or layer are at least partially covered by waterproof material, the absorbent material should be removed from the component or article and placed in a tea bag according to the procedure indicated in the above method before proceeding with the test).

  Of course, the centrifuge may require balancing by placing an identical sample, or any other balancing mass centered at 180 along the arc of the centrifuge basket.

  The core or layer is tested and weighed before being placed in the tea bag, before each test, to obtain its dry weight.

  The tea bag is available from Teekanne in Diisseldorf, Germany The tea bag is heat-sealable with a sealing device for standard kitchen plastic containers (for example VACUPACK 2 PLUS from Krups, Germany) Centrifugation is 1 o carried out in a centrifuge Bauknecht W 51 30, Bosch 772 NZK 096 or equivalent (diameter 230 mm).

  The centrifugal capacity in the tea bag (TCC) is calculated as follows: TCC = 1 (weight of the core or the layer in the tea bag, after centrifugation) (weight of the tea bag after centrifugation) (weight of absorbent core or dry layer) l.

  The absorption capacity C as used here is then calculated as follows: the above test is repeated twice for two other cores or articles which are identical to the core or to the layer of the first test above, and the average TCC is calculated from these three replicas and constitutes the absorption capacity C, as used here.

'FR 0216413 18 04 2003

Claims (6)

  1 disposable diaper comprising a back sheet (20) having a longitudinal axis of length A, a top sheet and an absorbent core having a longitudinal axis of length B, this back sheet (20) having a first end region (40) and a second end region (41), placed towards each of the two ends of the longitudinal axis, and having between them a central region, the absorbent core (10) being superimposed on the central region of the back sheet (20), but not on the first and the second terminal region (40, 41), and the absorbent core 1 o having a total absorption capacity C, characterized in that: (a) the absorbent core (10) has an index absorption C / A of less than 0.75 and (b) the core (10) has an average thickness of less than 6.0 mm and / or the ratio of B to A is less than 0.8.   2 disposable diaper according to claim 1, wherein the absorbent core (10) comprises an absorbent gelling polymer.   3 disposable diaper according to claim 1 or 2, wherein the absorbent core comprises from 50% to 30% by weight (of the absorbent core) of fibers.   4 disposable diaper according to claim 1, 2 or 3, wherein the thickness of the absorbent core is less than 6 mm.   Disposable diaper according to claim 1, 2 or 3, wherein the ratio of B to A is less than 0.8.   6. Disposable diaper according to any one of the preceding claims, wherein A is 47 cm to 60 cm and B is 30 cm to cm. 7 Disposable diaper according to any one of the preceding claims, having a colored back sheet.   8 daytime use of a layer as defined in any one of the preceding claims, possibly being associated with the nighttime use of a second layer with a back sheet which has a longitudinal axis of length A, a sheet of surface and an absorbent core which has a longitudinal axis of length B, in which the ratio of B to A is 0.8 or more. 35