Stabilized absorbent core and products made therefrom.

- 28036 Madrid

IS 2 148 261 T3

DESCRIPTION

Stabalized absorbent core and products made with it.

The present invention relates to an absorbent product for use with the user's undergarment and to an absorbent core for use in an absorbent product suitable for placement in the user's undergarment, according to the preamble of claims 1, 11 and 12. The preamble of said claims is based on patent document EP-A-0 376 761.

Patent document EP 0 376 761 refers to an article for feminine hygiene that comprises an absorbent material consisting of a fluff impregnated with a mixture formed of a bacteriostatic and fungistatic agent and a deodorant in a non-volatile hydrophobic solvent adhered to the cellulose fibers.

Patent document US-A-4 576 596 discloses a com a sanitary napkin having an absorbent layer folded therethrough to form a top layer and a folded bottom layer that abut each other in the vicinity of the central portion of the napkin. A thin extra-absorbent layer is located within the fold and distal folded position of the absorbent layer. An additional fold is provided by means of an additional layer. The known pad can have four absorbent layers and a raised central area. A further embodiment of such a known napkin provides a single pleated open central area with a folded portion located on top of the napkin.

Despite the many advantages achieved in the design of absorbent products, such as diapers, incontinence articles and sanitary napkins, there is a constant need for improved products that offer the user greater safety. Ways to enhance capacity The absorbent properties of such products have been found and widely used, such as the inclusion of superabsorbent materials in the design of the products. However, despite the increased absorbent capacity, tests have shown that a surprisingly high proportion of such products still fail; that is, the user has to endure leaks and stains on clothing. In large part, these failures are due to the stresses imposed on the product during use. For example, a sanitary napkin is subjected to significant distortionary forces due to the body movements of the user. Said forces may tend to compress the pad laterally, causing it to twist or cake and thus present a smaller area for collection of fluids. Although this problem has been studied in the art, there is still a need for designs of new products that relieve with Such distortion problems are successful, but in turn can be easily manufactured, so that cost-effective products can be offered to users.

A number of patents have been published that disclose sanitary napkins having an absorbent pad folded with a particular configuration.

UK Patent Application GB 2,124,499A discloses a sanitary napkin with an absorbent felt folded along the longitudinal edges to provide a cavity in the bottom portion of the napkin.

US Patent 3,699,966 to Chapuis discloses a sanitary napkin comprising alternating layers of hydrophilic and hydrophobic material, with inwardly folded edges of hydrophilic material to define a channel extending through the central portion. on one side of the pad.

Other patents disclosing pads containing absorbent wadding. Bent folded into a "C-fold" configuration are US Patents 3,667,468 to Nystrand et al., US 3,954,107 to Chesky et al. and US 3,364,931 to Hirsch.

The aforementioned need for new product designs is achieved by what is described in the characterizing part of claims 1, 11 and 12. In this way, the present invention refers to an absorbent product to be used with the user's undergarment. , such as a sanitary napkin, comprising:

a fluid-permeable cover facing the body, a fluid-impermeable back facing the undergarment, and an absorbent pad between the two, said absorbent pad being folded over itself along a pair of generically parallel longitudinal fold lines to form a middle panel and two side panels, said intermediate panels and the two side panels having a width that sustains cially equivalent in the central transverse axis of said absorbent pad. The intermediate panel is preferably located on the body-facing side of the absorbent pad.

In some preferred embodiments, one or more panels of the absorbent sheet are embossed with patterns to effect the uptake, retention and transport of the fluids in the product. For example, in a preferred embodiment, the panel facing the body is provided with a plurality of channels in the longitudinal direction and one of said side panels is provided with a plurality of channels in the direction of the width, said channels serving to wick fluids away from the center of the absorbent pad.

The absorbent product of the invention offers numerous advantages. The folds in the lateral edges of the absorbent core provide a three-fold absorbent web with a resistance to mechanical flexion in This in turn gives the web an enhanced ability to supply a spring-like force to resist deformation, folding or caking.

Brief description of the drawings

Figure 1 is a top view of the absorbent sheet of the present invention prior to being folded.

Figures 2 and 3 are sections of batts ab2

ES 2 three-fold sorbents used in the present invention.

Figure 4 is a section of a sanitary napkin incorporating the absorbent pad three times folded.

Figures 5, 6, 7, 8 and 9 are top views of the different absorbent sheets of the present invention, before (a) and after (b) being folded. Detailed description of the invention

The absorbent pad used in the present invention is illustrated in Figures 1-3 and 5-9. The absorbent pad 10 comprises three panels 11, and 13. The side panel 11 is defined by a long edge. longitudinal 14 and a longitudinal fold line 15. The intermediate panel 12 is defined by a longitudinal fold line 15 and by the longitudinal fold line 16. The side panel is defined by the longitudinal fold line 16 and by the edge 17. The transverse ends of each of the three panels are defined by transverse edges 18 and 19. The dotted line 24 represents the transverse central axis of the absorbent web, an axis located midway between transverse edges 18 and 19.

The fold lines 15 and 16 are generally parallel to each other and are positioned so that each of the panels 11, 12 and 13 has a substantially equivalent width on the central transverse axis of the absorbent web. When panels 11 and 12 are folded on fold lines 15 and 16, the absorbent web is not in the traditional fold-in configuration.

C. On the contrary, there is an overlap in their Stance of side panel 11 and middle panel 12. By substantial overlap is meant that side panel 11 is folded over middle panel 12 so that longitudinal edge 14 approaches fold line 16 on the central transverse axis. 24 while still allowing its folding by line 16, in the manner shown in the figures. Similarly, the side panel 13 is folded over the opposite face 22 of the side panel 11, so that the longitudinal edge 17 approaches the fold formed in the fold line 15 on the central transverse axis.

24.

As shown in Figure 1, panels 11, 12 and 13 may have a substantially equivalent width along their entire length. However, in variant embodiments shown in Figures 5, 6, 7 and 8 the three panels may have a substantially equivalent width at the central transverse axis 24, but either the side panel 11 or 13 or both panels. s can be used to form a smaller width as they extend longitudinally from the central transverse axis in a variety of ways. By altering the shapes of the side panels 11 and / or 13, it will be possible to provide an absorbent web that is thicker in the central region where greater absorbency is required and thinner in distal regions where less absorbency is required, the distal regions contributing thinner to provide greater user comfort. For example, as shown in Figures 5, 6, 7 and 8, the side panels 11 and 13 could be generally trapezoidal in shape.

261 T3 4

The three panels 11, 12 and 13 may be of substantially equivalent length, as shown in Figure 1, or their lengths may vary. For example, in the embodiments illustrated in Figure 9, each of the side panels 11 and 13 is shorter in length than the inner panel. medium 12. Such a configuration also provides a pad that is thicker in the central region than at the longitudinal ends, providing increased comfort and greater absorbency where needed.

The absorbent web is preferably formed of absorbent pulp fibers and resilient synthetic fibers. Pulp fibers are generically formed from fibrilized wood pulp sheets and generally comprise a combination of long and short fibers. Suitable resilient synthetic fibers include, but are not limited to, polyester and polyethylene fibers. Such fibers tend to be "long", that is, ranging from about 1.59mm to about 12.7mm in length. Although pulp fibers give the web greater absorbency, synthetic fibers provide greater resilience to the web.

It is considered desirable to have a greater proportion of fibr more pulp than synthetic fibers in the panel facing the body of the absorbent nap, panel 12, to enhance the ability of said panel to rapidly absorb fluids, and a lower proportion of pulp fiber with respect to the synthetic fibers in the facing panel to absorbent fleece garment, panel 13, where rapid fluid intake is not as critical, but added resilience is beneficial.

The relative amounts of fibers in each panel can vary between 100 and 0% pulp and between 0 and 100% of synthetic fiber. When the middle panel 12 is on the body facing side of the web it is desirable to have rapid fluid distribution in the middle panel so that the middle panel can be beneficially formed from 100% pulp. In the side panels 11 and 13, where fluid absorption is not critical, 100% synthetic fiber can be used to increase its resilience. It has been found that a comp Osyuan of approximately 65% ​​pulp fiber and 35% synthetic fiber provides good resilience to the absorbent web.

The resilience of the batt will vary greatly with the length and type of synthetic fibers used. Since the length and resilience of most synthetic fibers decrease once they have been heated above their melting temperature, it is desirable to use short synthetic fibers, less than 1.59 mm, with a low melting temperature in conjunction. with long synthetic fibers with a high melting temperature. Shorter fibers with a lower melt temperature are used to bond pulp and synthetic fibers together and longer fibers with a higher melt temperature will provide the desired resilience property. For example, a batt with a composition of 65% pulp, 20% synthetic fibers with low melting temperature and 15% synthetic fibers. longest high melting temperature (one to3

ES 2 148 261 T3 such as 35% synthetic fibers) provides an absorbent web with better resilience than a standard 65/35 composition.

The web could be formed by known techniques in which pulp and / or synthetic fibers are laid in the air. To form a stable web, the fibers in the web are preferentially bonded to each other. This can be done by heating the batt to a temperature above the melting temperature of synthetic fibers, so that said fibers melt and bond together. Alternatively, bonding agents such as different thermo-bonding fibers, hot melt spray adhesives and adhesive powders may be used. Specific means that can be used to bond the fibers together include conventional ovens, dielectric ovens (radio frequency and microwave), infrared ovens, rollers heated calendering machines, forced hot air ovens, forced hot air during the panel forming process and hot melt spray adhesives during the panel forming process.

The figures illustrate a three-fold configuration of the adsorbent web. The folded edges formed by the fold lines 15 and 16 are believed to provide the adsorbent web with resistance against bending forces. This gives the fleece the characteristics of supplying a spring force to resist deformation, bending or flexing when subjected to lateral shrinkage forces, such as those applied to the lateral edges of a sanitary napkin by the movement of the thighs of the patient. Username.

Any or all of the panels 11, 12 and 13 may be provided with an embossing to enhance the distribution of the fluid, increase its conformity and / or its aesthetic appearance. Said engraved drawings may include, without being limited thereto, channels along the length or width, diagonal channels, and embossing areas.

In one embodiment illustrated in Figure 1, the intermediate panel 12 has a plurality of longitudinal channels 20 formed therein and the side panel 11 has a plurality of channels 21 along its width formed therein. In another embodiment illustrated in Figure 5, the side panel 13 has a plurality of longitudinal channels and the intermediate panel 12 has a plurality of channels in the width direction. Figure 7 shows a side panel 13 having a plurality of longitudinal channels and an intermediate panel 12 having a plurality of diagonal channels. The channels provided in the various panels of the absorbent sheet serve to absorb the fluid and direct it to all areas of the absorbent sheet.

In the embodiment illustrated in Figure 6, the pa The side 11 is provided with longitudinal channels and the intermediate panel 12 has been embossed to provide a plurality of raised circular areas 40 on the panel. The raised circular areas provide a feeling of smoothness and softness and the indentations around these areas provide a reservoir to hold the fluid.

The embossed patterns supplied on the absorbent panels may be applied by means known in the art, such as by means of a patterned calendering roll which may or may not be heated. The drawing / step of the embossing of the channels may vary according to the respective roller, as well as the types of drawings. An embossing station may be designed to house upper and lower calendering rollers that may be set in a male versus female or male orientation facing a solid anvil. The rollers may be heated or kept at room temperature in f The composition of the batt and the desired "finish" required for the specific products. In general, a permanent finish can be done on a 65-100% pulp web without the application of heat. A lower amount of moisture, between 0.5 and 5% by weight of the batt, can be added to the batt when it contains a percentage of pulp to obtain a stronger and more permanent finish. Batts with a lower percentage of pulp may require the application of heat to obtain a permanent finish.

The pulp pad can be processed as it passes through the embossing station, the embossing depth being determined by the thickness and composition of the pulp. For example, the specifications of the longitudinal rollers can be as follows: rollers 25.4 to 50.8 mm wide with a 3.18 to 12.7 mm male channel pattern, 3.18 to 12 mm female, 7 mm and a depth of 3.18 to 6.35 mm, an eangu what from 60 to 90^°. Preferably, the channels or desified areas are at least 6.35 mm from the edges and ends of the panel.

Preferably, the honeycombs of the three-fold absorbent sheet are joined together to retain the three-fold configuration, which could be done by applying areas of adhesive 23, as illustrated in Figure

two. Alternatively, the panel three times folded may be subjected to the application of heat and / or calendering to effect the joining of the honeycombs by joining the thermoplastic fibers inside, in the manner illustrated in Figure 3.

Additional fibrous or particulate agents may be incorporated into the fiber batt. For example, it may be desirable to incorporate superabsorbent particles or fibers into the web to enhance the absorbency of the web. Such superabsorbent agents are well known in the art. A type of material su Perabsorbent supplies particles or fibers that can be chemically described as being composed of a backbone of natural or synthetic polymers with hydrophilic groups or polymers containing hydrophilic groups that are chemically bonded to the backbone or an intimate mixture therewith. Included in this class of materials are regenerated and modified natural polymers such as the aforementioned polysaccharide types, including for example cellulose and staridoen and regenerated cellulose that is modified by carboxylalkylated, phosphonoalkylated, sulfoalkylated or phosphorylated processes to make them highly hydrophilic. Such modified polymers may

ES 2 also be cross-linked to improve its insolubility in water.

In addition, it may be desirable to incorporate odor control agents into the web, such as, but not limited to, baking soda powder and activated charcoal.

Instead of adding ag superabsorbent or odor control entities on the web itself, such materials may be placed randomly or in layers between the panels and the three-fold web. For example, the baking soda powder and the particulate or fibrous superabsorbent material may be placed on the surface of the absorbent batt prior to its folding, so that it is layered between the panels in the final configuration of the batt. As another variant example, a panel of superabsorbent material, such as a tissue / superabsorbent laminate or a processed peat moss panel, which may be represented by the insert 30 shown in Figure 4, could be placed between the panels of the fleece three times folded.

As illustrated in the figures, each of the three panels of the absorbent web has a generally uniform thickness. However, the thickness of the panels may vary to provide different profiles. For example or, it may be desirable to have extra thickness in the center of the pad so that the thickness of one or more of the panels may be greater in the center than one or both of the transverse or longitudinal edges.

The dimensions of the absorbent pad are not critical and may be varied according to the type of absorbent product desired. In general, for a full protection sanitary napkin the absorbent pad could be about 209.2 mm long and about 177.8 mm wide, prior to being folded three times.

A sanitary napkin incorporating the three-fold absorbent pad described above is illustrated in Figure 4. The ab261 T3 sorbent batt 8 is contained within a body-facing, fluid-permeable upper cover 31 and a fluid-impermeable lower backing layer 32 facing the undergarment. The adhesive means 34 serves to firmly adhere the pad to the garment. inside the user. The attachment means may comprise adhesive lines covered with release strips 35 which when detached from the adhesive strips expose the tacky adhesive. Alternatively the attachment means could comprise a pressure sensitive adhesive tape, said tape having a first side permanently adhered to the liquid impermeable cover 32 and a second opposite side adapted to be temporarily attached to the wearer's undergarment.

The absorbent nap is preferably placed in the napkin, so that the intermediate panel 12, which has longitudinal channels, represents the side of the nap facing the body, so that the side panel 11, which has channels through its width is the intermediate part of the batt.

The fluid-permeable facing cover 31 disposed on the absorbent structure of the present invention could be a film or ela that has a high degree of moisture permeability. For example, the fabric could be made of a bicomponent fiber of polyester, polyethylene, polypropylene, nylon, rayon or the like. The most suitable fabrics have uncommon characteristics of high elongation, smoothness, softness and suitable fabric behavior. Perforated or non-continuous films are also satisfactory. Although the moisture-permeable cover, a cover of the type that upon penetration of moisture, prevents backflow of body fluid when the absorbent structure is close to saturation, is preferred.

The fluid impermeable backing layer 32 may be a liquid impermeable polyolefin film, such as polyethylene or polyethylene terephthalate.