Method of making of absorbent core

The present invention relates to an absorbent core for disposable absorbent articles such as sanitary napkins and disposable diapers, and a method for producing the same.

Disposable absorbent articles such as disposable diapers and women's hygiene articles are well known in the art. Such articles are designed to absorb emissions from the wearer's body. Disposable absorbent articles are typically between a fluid-permeable body contact layer called the topsheet, a fluid-impermeable layer called the backsheet joined to the topsheet, and between the topsheet and the backsheet. It has an absorbent layer called an absorbent core sandwiched between the two. During use, fluid exiting the wearer's body penetrates the disposable absorbent article through the topsheet and is stored in the absorbent core. The backsheet prevents any extra non-absorbed fluid from leaving the disposable absorbent article. For disposable absorbent items such as sanitary napkins intended to be worn with other garments, the backsheet can be a layer facing the garment and typically helps prevent garment stains.

Other elements can be included in the disposable absorbent article, including an additional absorbent layer having a structure designed for a particular function. For example, the second topsheet can be an absorbent layer that is located between the topsheet and the absorbent core and has a structure designed to separate the fluid from the topsheet and quickly suck it into the absorbent core. Similarly, multiple layers of absorbent cores can be used, and each layer has fluid processing properties designed to ensure fluid movement within the absorbent core for reliable storage. In addition, each layer of absorbent core material itself can be a layered or laminated structure with separate layers known in the art of air laying webs using multiple air laying heads or beams. In a layered absorbent core material, any one separate layer may contain a different type of fiber or fiber blend than the other separate layer.

It is known to design an absorbent core having a structure that facilitates fluid movement from the top sheet to the back sheet, i.e. away from the wearer's body. For example, fibrous layered absorbent cores with increased capillary action in each layer are known. Similarly, it is known to have a layered absorbent core whose permeability decreases as each layer follows away from the topsheet. In this method, the fluid infiltrating through the topsheet first contacts a layer with high permeability and low capillary action to facilitate rapid fluid uptake. From this first layer, the fluid can contact a layer with lower permeability and higher capillary action, which allows the fluid to continue to move away from the topsheet, albeit at a slower rate. It has become like. This is generally acceptable because once the fluid has left the wearer's body, the speed at which the fluid moves to other parts of the absorbent core becomes insignificant.

In known absorptive cores, there is a well-known trade-off between material permeability and its capillary action. In general, known materials with relatively higher permeability have relatively lower capillarity and vice versa. For disposable absorbent articles for which it is desirable to separate both parameters, a positive change in one of these parameters results in a corresponding negative change in the other. This property trade-off has been due to the balance of absorbable core properties in the past, as permeability directly affects the rate of material acquisition and capillary action directly affects fluid movement by limiting capillary pressure. The result was that it was selected for. However, an absorbent structure that includes an absorbent core resulting from this inevitable trade-off cannot simultaneously achieve the desired level of acquisition rate and reliable fluid transfer to the reservoir.

<p> Therefore, it would be desirable to have an absorbent article and an absorbent core material capable of simultaneously maintaining both permeability and capillary pressure in the absorbent core at the desired levels.</p><p> In addition, it would be desirable to have an absorbent article and an absorbent core material that minimizes the negative side of either one when one or the other of the permeability or capillary pressure is more optimized. ..</p><p> In addition, having an absorbent article and an absorbent material that manages the trade-off between permeability and capillary pressure so that a relatively higher permeability can be achieved without reducing the capillary pressure. Would be desirable.</p>

<p> In one aspect, the invention relates to an absorbent article that can be a sanitary napkin. The absorbent article comprises a topsheet bonded to the backsheet and has an absorbent core material disposed between them, the absorbent core material exhibiting a separate raised portion on one side of the fibrous absorbent. It is a sex material. The raised portion defines a continuous network of channels, and the channels define a hollow area adjacent to the topsheet of the sanitary napkin.</p><p> In another aspect, the invention relates to a method of making an absorbent core for use in an absorbent article. The method is The process of providing the first absorbent fiber web material and The process of providing the second absorbent fiber web material and A pair of rolls forming a nip can be provided through which the first and second absorbent fiber web materials can be processed, and the pair of rolls can be ring rolling, SELF, micro SELF. , And a process selected from a process consisting of rotary knife aperturing, and The process of deforming the first absorbent fiber web material by processing through a pair of rolls, The process of deforming the second absorbent fiber web material by processing through a pair of rolls, Includes a step of combining first and second absorbent fiber web materials to form an absorbent core.</p><p> In another aspect, the invention relates to an absorbent core for a disposable absorbent article. The absorbent core material may be a fibrous airlaid non-woven web containing cellulose fibers, having a first density and having a plurality of separate out-of-plane deformities, where the out-of-plane deformities have a second density. The second density is smaller than the first density.</p>

<figref num="1">A partially cutaway perspective view of a sanitary napkin that embodies the present invention.</figref><figref num="2">Schematic of the process for mechanical modification of web material through the nip of a pair of meshing rolls.</figref><figref num="3">Schematic of a pair of meshing rolls in a process commonly referred to as ring rolling.</figref><figref num="4">An enlarged partial cross-sectional view showing the mutual engagement of the teeth and grooves of each roll of the ring rolling device shown in FIG.</figref><figref num="5">A further enlarged view of the ring rolling device shown in FIG. 3, showing multiple teeth and grooves interengaged with a web of material between them.</figref><figref num="6">Schematic of a pair of meshing rolls in a process commonly referred to as the SELF process.</figref><figref num="7">Schematic of the process for denaturing the web by the SELF process.</figref><figref num="8">Schematic of the web after passing between a pair of meshing SELF rolls.</figref><figref num="9">A pattern that can occur in an absorbent material by passing the material between a pair of meshing SELF rolls.</figref><figref num="10">A pattern that can occur in an absorbent material by passing the material between a pair of meshing SELF rolls.</figref><figref num="11">Side view of the roll for use in the micro SELF process.</figref><figref num="12">A perspective view of a roll for use in a micro SELF device.</figref><figref num="13">Enlarged perspective view of the teeth on the micro SELF roll.</figref><figref num="14">Schematic of the rotary blade device (RKA) and process.</figref><figref num="15">Part of an embodiment of a roller of a rotary blade device having multiple teeth useful for making a perforated web.</figref><figref num="16">An enlarged perspective view of an embodiment of a serrated roll tooth of a rotary blade device.</figref><figref num="17">A side view of a SELF roll showing typical dimensions useful in some embodiments of the present invention.</figref><figref num="18">Sectional drawing of the roll shown in FIG. 17 cut along lines 18-18, showing typical dimensions useful for some embodiments of the present invention.</figref><figref num="19">Sectional view of SELF roll teeth showing typical dimensions useful in some embodiments of the present invention.</figref><figref num="20">An enlarged side view of a roll tooth shown in FIG. 17, showing typical dimensions useful in some embodiments of the present invention.</figref><figref num="21">Planar layout of a SELF roll with a staggered tooth pattern showing typical dimensions useful in some embodiments of the present invention.</figref><figref num="22">Sectional cross section of the SELF roll shown in FIG. 20, cut along lines 22-22.</figref><figref num="23">Some enlarged plan views of the SELF roll teeth shown in FIG. 20, showing typical dimensions useful for some embodiments of the present invention.</figref><figref num="24">A partial perspective view showing an embodiment of a tooth on an RKA roll showing typical dimensions (in mm) useful for some embodiments of the present invention.</figref><figref num="25">Top view of the teeth of the RKA roll shown in FIG. 24, showing typical dimensions (in mm) useful for some embodiments of the present invention.</figref><figref num="26">Sectional view of the teeth on the RKA roll of FIG. 24, cut along lines 26-26 of FIG. 25, showing typical dimensions (in mm) useful for some embodiments of the invention.</figref><figref num="27">Sectional view of the teeth on the RKA roll of FIG. 24, cut along lines 27-27 of FIG. 24, showing typical dimensions (in mm) useful for some embodiments of the invention.</figref><figref num="28">A side view of a SELF roll suitable for the present invention.</figref><figref num="29">FIG. 8 is a view of the outer surface of the SELF roll shown in FIG.</figref><figref num="30">Schematic details of the roll teeth shown in FIGS. 28 and 29, showing typical dimensions (in inches).</figref><figref num="31">A partial perspective view showing an embodiment of a tooth on an RKA roll showing typical dimensions (in mm) useful for some embodiments of the present invention.</figref><figref num="32">Top view of a portion of the RKA roll shown in FIG. 31, showing typical dimensions (in mm) useful for some embodiments of the present invention.</figref><figref num="33">33-33 partial cross-sectional view of FIG. 32 showing an embodiment of a tooth on an RKA roll showing typical dimensions (in mm) useful for some embodiments of the present invention.</figref><figref num="34">FIG. 31 is a side view showing the teeth of FIG. 31, showing typical dimensions (in mm) useful for some embodiments of the present invention.</figref><figref num="35">A partial perspective view showing an embodiment of a tooth on an RKA roll showing typical dimensions (in mm) useful for some embodiments of the present invention.</figref><figref num="36">Top view of a portion of the RKA roll shown in FIG. 35 showing typical dimensions (in mm) useful for some embodiments of the present invention.</figref><figref num="37">37-37 partial cross-sectional view of FIG. 36 showing an embodiment of a tooth on an RKA roll showing typical dimensions (in mm) useful for some embodiments of the present invention.</figref><figref num="38">FIG. 35 is a side view showing the teeth of FIG. 35, showing typical dimensions (in mm) useful for some embodiments of the present invention.</figref><figref num="39">Schematic of the web of the present invention.</figref><figref num="40">Schematic of the web of the present invention.</figref>

One embodiment of the present invention is an absorbent core that is useful as a fluid storage component of disposable absorbent articles such as women's hygiene articles. An embodiment of the women's hygiene article (sanitary napkin 10) of the present invention is shown in the perspective view of FIG. The present invention is disclosed in FIG. 1 as an embodiment of a sanitary napkin 10, but when the disclosed mechanism of the present invention is also incorporated into other women's hygiene articles such as incontinence pads and panty liners. Can also be useful. Therefore, the following description is relevant to sanitary napkins, but is generally applicable to women's hygiene products. Similarly, the absorbent cores of the present invention can be found useful in other disposable absorbent articles, including disposable diapers, adult incontinence devices, hemorrhoid treatment pads, bandages and the like. Moreover, the structures produced by the methods and devices disclosed herein are inhomogeneous fibers such as wiping supplies, polishing pads, floor wiping mop pads (eg SWIFFER® pads), etc. Usefulness can be found in other webs where the surface texture of the structure is advantageous.

The sanitary napkin 10 can be thought of as three areas, two terminal areas 12 and 14, each of which constitutes about one-third of the total length, and an intermediate area 16. The sanitary napkin 10 has a body-facing surface (or side surface) 15 that contacts the user's body during use and a clothing-facing surface (or side surface) 17 that contacts the user's underwear during use. Generally, it can be said that each component layer of the sanitary napkin 10 has a body-facing side and a garment-facing side, which are determined by orientation with respect to the use of the article. The sanitary napkin 10 has a longitudinal centerline L and a transverse centerline T, which are in the plane of the sanitary napkin when in a flat arrangement, as shown in FIG. They are perpendicular to each other. In one embodiment, the sanitary napkin can be generally symmetrical at both centerlines, whereas in other embodiments, the sanitary napkin can be largely asymmetric at either centerline. In the embodiment shown in FIG. 1, the sanitary napkin 10 is approximately symmetric at the longitudinal centerline L and approximately at the transverse centerline T. Women's hygiene articles are also known in the art as "flaps" or "wings" (not shown in Figure 1) that are folded in the crotch area of the user's underwear and are intended to cover the panty elastic. It can also be provided with some lateral extensions.

The sanitary napkin 10 can have any shape known in the art for women's hygiene products, which can be a generally symmetrical "hourglass" shape, or one, as shown in FIG. One end of the pad, which has a shape that tapers inward, from a relatively larger transverse width within a portion of the end area to a relatively smaller transverse width in the intermediate area. For example, the maximum transverse width of the terminal area 12 is greater than the maximum transverse width of the other terminal, eg, the terminal area 14. Transverse width is defined herein as an end-to-end dimension across an article, measured approximately parallel to the transverse centerline T. These pads can be described as pear-shaped, bicycle stool shape, trapezoidal, wedge-shaped, or else one end in the maximum width dimension has two ends larger than the other 2 It may be described in a form that implies the shape of the dimension.

The sanitary napkin 10 has an absorbent core 20 and is capable of absorbing and accommodating body fluids excreted during use. In some embodiments of sanitary napkins, panty liners, incontinence pads, or other such devices of the invention, an absorbent core is not required and the pad is a topsheet (it may have some absorbent capacity). And consists only of a fluid impermeable backsheet. The absorbent core 20 may be formed from any of materials well known to those skilled in the art. Examples of such materials include multiply crimped cellulose lumps, fluffed cellulose fibers, wood pulp fibers, also known as air felts, woven fibers, fiber mixtures, lumps or cores of fibers, air-laid webs of fibers. (Airlaid web), a web of high fiber, and a mixture of high fibers.

In one embodiment, the absorbent core 20 is relatively thin and can be less than about 5 mm or less than about 3 mm thick, or less than about 1 mm thick. The thickness can be determined by measuring at the midpoint along the longitudinal centerline of the pad while under uniform pressure of 1.72 kPa (0.25 psi) by any means known in the art. it can. The absorbent core may include an absorbent gel material that includes fibers of the absorbent gel material (AGM), as is known in the art.

The absorbent core 20 may be molded or cut into a shape and its outer edge may define the core periphery 30. The shape of the absorbent core 20 can generally be rectangular, circular, oval, oval and the like. The absorbent core 20 may be centered approximately at the longitudinal centerline L and the transverse centerline T. The properties of the absorbent core 20 can be such that more absorbers are located near the center of the absorbent article. For example, the absorbent core can be thicker in the middle and tapered at the edges in various ways known in the art.

The absorbent core 20 can be the type of air-laid core disclosed in US Pat. No. 5,445,777 or US Pat. No. 5,607,414. Absorbent cores are of the type commonly referred to as HIPE foam, such as those disclosed in US Pat. No. 5,550,167, US Pat. No. 5,387,207, US Pat. No. 5,352,711, and US Pat. No. 5,331,015. And may include a highly absorbent core material. In one embodiment, after desorption at 30 cm, the absorbent core has a capacity of less than about 10% of its free absorption capacity, a capillary absorption pressure of about 3 to about 20 cm, a capillary desorption pressure of about 8 to about 25 cm, 5.10 kPa ( It can have a resistance to compressive deflection of about 5 to about 85% when measured under a limiting pressure of 0.74psi), and a free absorption capacity of about 4 to 125 grams per gram. Each of these parameters can be measured as described in US Pat. No. 5,550,167 (Des Marais, issued August 27, 1996). One advantage of utilizing airlaid or HIPE foam cores as disclosed is that the absorbent core can be made very thin. For example, the average caliper (thickness) of the absorbent core of the present invention can be less than about 3 mm, or less than 2 mm, and the thickness can be less than about 1 mm.

The sanitary napkin 10 can have a liquid permeable backsheet 22 to prevent the absorbed excrement from coming into contact with the wearer's clothing. The backsheet 22 may include any of the backsheet materials known in the art, such as polymer films and film / non-woven laminates. To provide some flexibility and vapor permeability to the garment-facing side of the sanitary napkin 10, the backsheet 22 can be a vapor-permeable outer layer of the garment-facing side of the sanitary napkin 20. .. The backsheet 22 can be formed from any vapor permeable material known in the art. The backsheet 22 may include a microporous film, a perforated molded film, or other polymer film that is vapor permeable or vapor permeable, as is known in the art. One suitable material is a flexible, smooth, adaptable vapor permeable material, such as a non-woven web that is hydrophobic or made hydrophobic and nearly liquid permeable. The non-woven web can provide flexibility and compatibility to provide comfort and suppress the generation of noise so as not to produce unwanted noise during movement.

To provide flexibility closest to the body, the sanitary napkin 10 can have a layer facing the body, which is referred to herein as the topsheet 26. The topsheet 26 can be formed from any of the flexible, smooth, adaptable porous materials that are comfortable against human skin and allow fluids such as urine or vaginal excrement to pass through. The topsheet 26 may include a fibrous non-woven web and may include fibers as known in the art, including bicomponents and / or molded fibers. Bicomponent fibers may include polypropylene (PP) and polyethylene (PE) in known configurations including core / sheath, parallel, sea-island, or pie. The molded fibers can have a tri-lobal, an H-shaped cross section, or any other known cross-sectional shape. The topsheet 26 is also a liquid permeable polymer film, such as a perforated film, or a perforated three-dimensional, as is known for sanitary napkins, such as ALWAYS® sanitary napkins. It can be a molded film.

At least one, preferably both, of the topsheet 26 and the backsheet 22 defines a shape, the edges of which define the outer periphery 28 of the sanitary napkin 10. In one embodiment, both the topsheet 26 and the backsheet 22 define the outer periphery 28 of the sanitary napkin 10. These two layers can be punched out as is known in the art, for example, after combining all the components into the structure of the sanitary napkin 10 as described herein. However, the shape of either the topsheet 26 or the backsheet 22 can be defined independently.

Disposable absorbent articles may include lotions, skin care ingredients, air fresheners, odor suppressants, and other constituents. In one embodiment, a lotion that may include a skin care composition may be added to the topsheet by spraying, extrusion or slot coating. The skin care composition can be hydrophilic or hydrophobic, from about 0.001% to about 0.1% by weight hexamidine, about 0.001% to about 10% by weight zinc oxide, about 0.01% to about 10% by weight niacinamide, and petrolatum. Can have a carrier such as. The lotion is a compound or neat and can include glycols, including polypropylene glycol. Lotions and skin care agents are co-owned US Serial Number 10 / 152,924 (filed May 21, 2002), US Serial 09 / 968,154 (US Serial Number 10 / 152,924). US Serial Number 09 / 968,154) and US Serial No. 10 / 152,924 (US) It may be as described in Serial Number 10 / 152,924) (filed May 21, 2002).

At least one fluid permeable second topsheet 24 may intervene between the absorbent core 20 and the topsheet 26. The second topsheet 24 may aid in rapid acquisition and / or distribution of fluid and preferably communicates with the absorbent core 20. In one embodiment, the second topsheet 24 does not completely cover the absorbent core 20, but may extend laterally to the core periphery 30. In one embodiment, the topsheet, second topsheet, or absorbent core may have a layered structure, the layers facilitating fluid transport by differences in fluid transport properties such as capillary pressure. In one embodiment, the second topsheet can function as an absorbent core layer and is considered to be one of the multi-layered absorbent core systems.

Each web of absorbent core material itself can be a layered structure with separate layers, as is known in the art of air laying webs using multiple air laying heads or beams. In a layered absorbent core material, any one separate layer may contain a different type of fiber or fiber blend than the other separate layer.

In one embodiment, the absorbent core 20 does not extend laterally outward to the same extent as either the topsheet 26 or the backsheet 22, but the sanitary napkin 10 outer peripheral 28 is from the outer peripheral 30 of the core. It can be substantially increased. In this method, the area of the sanitary napkin 10 between the core periphery 30 and the outer periphery 28 of the sanitary napkin 10 can define a breathable area, which allows vapor to be applied to the sanitary napkin when worn. It passes through a portion of the napkin, which allows steam to escape, providing a drier comfort. Sanitary napkins with a breathable area can follow the teachings of US Serial No. 10 / 790,418 (US Ser. No. 10 / 790,418) (filed March 1, 2004).

All components can be adhered to each other by means well known in the art using adhesives, including hot melt adhesives, as is known in the art. The adhesive can be Findlay H2128 UN or Savare PM 17, and can be applied using the Dynafiber HTW system.

As is typical for sanitary napkins and the like, the sanitary napkin 10 of the present invention may have a panty-fixing adhesive 18 disposed on the garment-facing side surface 17 of the backsheet 22. The panty fixing adhesive 18 can be any known adhesive used for this purpose in the art and, as is well known in the art, covered with release paper 19 prior to use. obtain. In the presence of flaps or wings, the panty-fixing adhesive may be applied to the side facing the garment so that it contacts and adheres to the underside of the wearer's panties.

The above disclosure is meant to generally describe the basic parts of a women's hygiene article, such as sanitary napkins as is known in the art. This description is not intended to be limiting. Any or all of various known elements, mechanisms, processes such as known sanitary napkins, panty liners, sanitary napkins, etc., when desired or required for the benefit of commercial production or specific use. , Can be incorporated into the women's sanitary articles of the present invention. For example, sanitary napkins can comply with the disclosure of US Pat. No. 4,950,264 (Osborn III, issued August 21, 1990), and incontinence pads can comply with US Pat. No. 5,439,458 (US Pat. No. 5,439,458). The disclosure of Noel et al., Published August 8, 1995) can be followed.

The present invention utilizes absorbent materials that may include a second topsheet and / or an absorbent core for sanitary napkins, which, from the as-finished state, are accompanied by a corresponding reduction in capillary pressure. It is modified to be more permeable, thereby allowing the second topsheet and / or core of the invention to gain more rapidly and have greater retention capacity for unmodified and known materials. Has come to bring. These desirable properties can be imparted to known fiber web materials by forming with one or more known forming means, such as, for example, known methods for making extruded non-woven webs and air-laid fiber webs. Without being bound by theory, the denaturations disclosed herein produce denaturations of the base web in the form of relatively small, locally separate, increased permeability areas, which are substantially the same. Along with the undenatured area, it is believed that it can produce a web average, or "macro" effect, in which case the other can be improved without the expected adverse effects of permeability or capillary pressure on the other. Be done.

In one aspect, the known absorbent web material in the finished state is considered to be homogeneous throughout. Due to its homogeneity, the fluid treatment properties of the absorbent web material are not position dependent and are substantially uniform in any region of the web. Homogeneity can be characterized by, for example, density, basis weight, and the density or basis weight of any particular portion of the web is substantially the same as the average density or basis weight of the web. By the apparatus and method of the present invention, the homogeneous fibrous absorbent web material is no longer homogeneous and is modified to be inhomogeneous, thereby making the fluid treatment properties of the web material position-dependent. ing. Therefore, in the case of the heterogeneous absorbent materials of the present invention, at different locations, the density or basis weight of the web is substantially different from the average density or basis weight of the web. The heterogeneous nature of the absorbent web of the present invention minimizes one negative aspect of permeability or capillary pressure by providing high permeability to separate parts and high capillary action in other separate parts. Allows you to limit it. Similarly, the trade-off between permeability and capillary pressure is controlled to achieve relatively higher permeability without reducing capillary pressure. The heterogeneous web of the present invention appears to break the trade-off between permeability / capillary pressure. The forming means and the absorbent core material produced by the forming means will be described below.

In the present invention, four forming means known for transforming a generally flat fiber web into a three-dimensional structure are used to provide an as-finished absorbent material with a significant reduction in corresponding capillary pressure. It transforms into an absorbent material with relatively higher permeability without accompaniment. Each of the four forming means disclosed herein is disclosed as including a pair of meshing rolls, typically steel rolls with ridges or teeth and grooves that engage with each other. However, it is considered that other means of achieving the formation may be available, such as the deformed rollers and cord configurations disclosed in US Patent Application No. 2005/0140057 (published June 30, 2005). Therefore, all disclosures of a pair of rolls herein are considered equivalent to rolls and cords, and the claimed configuration detailing the two meshing rolls is equivalent to meshing rolls and cords. There is, in this case, the cord acts as a ridge on the meshing interengagement roll. In one embodiment, the paired meshing rolls of the present invention can be considered equivalent to the rolls and meshing elements, where the meshing elements are different rolls, cords, multiple cords, belts, flexible webs. , Or a strap. Similarly, although the disclosure of the four forming means has been exemplified herein, other known forming techniques such as creping, necking / consolidation, corrugating, embossing, button softening ( It is believed that button break), high temperature pin punching, etc. can produce an absorbent material with some relatively higher permeability without a significant reduction in the corresponding capillary pressure.

The first forming means useful in the present invention is a process commonly referred to as "ring rolling". With reference to the drawings, especially FIG. 2, for modifying the physical and performance properties of a web (eg, a non-woven web 34 drawn from and carried from a feed roll 36) by a process commonly referred to as ring rolling. The apparatus and method 32 are schematically illustrated. For absorbent core materials such as air-laid non-woven webs, ring rolling devices and methods can produce physically modified webs with improved fluid processing properties and altered dimensions. , Such modified materials may help improve both the performance and fit of disposable articles incorporated. In addition, after being modified with the disclosed equipment and after acquiring the desired physical properties described below, such modified non-woven webs can be used alone or in combination with other materials, if desired. Regardless of this, the modified non-woven web can be further processed without experiencing disassembly, tearing, or loss of integrity.

With reference to FIG. 2 again, the non-woven web 34 is pulled out of the feed roll 36 and travels in the direction indicated by the arrow. The non-woven web 34 is fed to a nip 38 formed by a pair of opposing forming rolls 40 and 42, which defining the forming rolls 40 and 42 as a first forming position 6. The structures and relative positions of the forming rolls 40 and 42 at the first forming position 50 are shown in the enlarged perspective view of FIG. As shown in the figure, the rolls 40 and 42 are supported by the rotating shafts 44 and 46 having rotating shafts arranged in parallel. Rolls 40 and 42 each include a plurality of ridges 52 that are axially spaced, parallel, peripherally extending, and evenly distributed, the ridges having a substantially square cross section. It can be in the form of thin fins, or it can have a triangular or inverted V shape when viewed in cross section. If they are triangular, the vertices of the ridges 52 are the outermost with respect to the surfaces of rolls 40 and 42. In any configuration, the outermost tip of the tooth is preferably rounded so as not to cut or tear material such as the non-woven web 34 passing between the rolls, as shown in more detail in FIGS. 4 and 5. It is tinged with.

The space between the adjacent ridges 52 defines concave grooves 54 that extend in the circumferential direction and are evenly distributed. When the tooth has a substantially rectangular cross section, the groove 54 can have a substantially rectangular cross section, and when the tooth has a triangular cross section, the groove can have an inverted triangular cross section. Thus, the forming rolls 40 and 42 each include a plurality of separated ridges 52 and alternating grooves 54 between each of adjacent pairs of teeth. The teeth and grooves do not have to be the same width, but as described below, the grooves are provided in order to receive the material passing between the interengagement rolls within each groove and locally extend it. It is preferable to have a width wider than the width of the teeth.

FIG. 4 is an enlarged partial cross-sectional view showing the mutual engagement of the raised portion 52 and the groove 54 of each roll. The ridges 52 have a tooth height TH and are preferably separated from each other at uniform distances to define the tooth pitch P. As shown in the figure, the ridges 52 of one roll extend partially into the grooves 54 of the opposing rolls to define the "engagement depth" E, as shown in FIG. The respective axes of rotation of the rolls 40 and 42 are separated from each other so that there is a predetermined space or gap between the opposing side walls of the interengaged teeth and grooves of the respective rolls. In addition, the tooth angle TA formed by adjacent teeth is shown.

FIG. 5 is a further enlarged view of several interconnected ridges 52 and grooves 24 and a web 25 of material between them. A portion of the web, which may be the non-woven web 34 shown in FIG. 1, is housed between the interengaged teeth and grooves of the respective rolls, as shown in the figure. By engaging the teeth and grooves of the roll with each other, the laterally separated portions of the web 34 are pushed into the opposing grooves 54 by the ridges 52. In the process of passing between the forming rolls, the force by which the raised portion 52 pushes the web 34 into the opposite groove 54 applies a tensile stress acting laterally to the web 34 in the web 34. This tensile stress allows the intermediate web compartments 58 between the tips of adjacent ridges 52 and over their spacing to extend or expand laterally to the web, resulting in a web in each of the intermediate web compartments 58. The thickness can be reduced locally. For non-woven webs, including air-laid webs, this elongation allows fiber reorientation, reduced basis weight, or controlled breakdown of fibers in the intermediate web compartment 58.

The portion of the web 34 between the adjacent ridges is locally stretched, but the portion of the web in contact with the tip of the ridge may not be stretched to the same extent. A ridge at the outer edge of the ridge 52 due to the presence of frictional force between the rounded outer edge of the ridge 52 and the adjacent region 60 of the web 34 in contact with the surface of the ridge at the outer edge of the ridge. Sliding movement of these parts of the web surface with respect to the part surface is minimized. As a result, in some cases, the properties of the web 34 in the area of the web in contact with the surface of the tip of the ridge change only slightly compared to the changes in web properties that occur in the intermediate web compartment 58.

Due to the increased width of the web as a result of the web 34 being locally stretched laterally, the web material coming out of the molding roll will remain in a substantially flat laterally expanded state. It may have a basis weight lower than the basis weight of the infiltrating web material. As the laterally stretched web exits between the forming rolls, it may contract laterally to its original width due to some tension applied to the web in the direction of web movement, in which case it is denatured. The erupting web may have the same basis weight as it had in the infiltrated state. However, if the exiting web is tensioned sufficiently in the direction of the web machine, the exiting web may be made to contract to a width narrower than its original width, in which case the web will shrink. It will have a larger basis weight than the original basis weight. On the other hand, the denatured web is loaded with so-called Mount Hope rolls, width dispensers, angled idlers, and angled nip (angles). The denatured exiting web has a smaller basis weight than its original basis weight if the web is subjected to additional sufficient elongation in the lateral direction of the web by passing it between nips) etc. as described above. Can be done. Therefore, by choosing a suitable forming roll tooth and groove configuration, by choosing a suitable tension level in the direction of movement of the web, and whether or not to add additional stretch in the lateral direction of the web to the web. By selecting, the resulting modified non-woven web can range the web width from about 25% to about 300% of the initial web width, and the basis weight is the original basis weight of the web. Less than, equal to, or greater than.

The ridge 52 may have a generally triangular cross section with a generally rounded ridge tip, as shown in FIGS. 4 and 5, with each of the opposing ridges and grooves of the molding rolls 40 and 42 Each of the ridges 52 is preferably of the same size so that they interact with each other along the entire axial length of each of the rolls. As shown in the figure, the raised portion 66 has a raised portion height RH (RH can also correspond to the groove depth, in one embodiment the tooth height and the groove depth. Note that they can be equivalent), the spacing between the ridges is called the pitch P. The engagement depth E, the height RH of the ridge, and the pitch P can be varied as desired, depending on the properties of the non-woven web being processed and the desired characteristics of the web being processed. For example, in general, the higher the level of engagement E, the higher the required elongation or mobility characteristics between the fibers that the processed web fibers should possess.

As an example, but not limited to, the peak-to-peak pitch P is about 0.38 cm (0.150 inch), the side walls are arranged at an angle of about 12 °, and the radius of the tip of the ridge is evenly rounded. A raised portion having a height RH (and groove depth) of about 0.76 cm (0.300 inch) of the raised portion from the tip to the base can be adopted in carrying out the present invention. As will be appreciated by those skilled in the art, the dimensions of the respective ridges and grooves can be varied over a wide range and are still effective in practicing the present invention. In this regard, additional structural details of suitable forming rolls are described in US Pat. No. 5,156,793, entitled "Methods for unevenly escalating zero strain stretch laminate sheets to impart varying degrees of elasticity. (Method for Incrementally Stretching Zero Strain Stretch Laminate Sheet in a Non-Uniform Manner to Impart a Varying Degree of Elasticity Thereto) "(Kenneth B. Buell)) et al., Published October 20, 1992); U.S. Pat. No. 5,167,897, entitled "Method for Incrementally Stretching a Zero Strain." "Stretch Laminate Sheet to Impart Elasticity Thereto" (Gerald M. Sheeter et al., December 1, 1992); and US Pat. No. 5,518,801, named "Sheet material exhibiting elastic-like behavior." (Sheet Materials Exhibiting Elastic- Like Behavior) (Charles W. Chappell et al., Published May 21, 1996).

A second means for transforming the web of the present invention is a process commonly referred to as a "SELF" or "SELFization" process, in which SELF represents a Structural Elastic Like Film. .. Although this process was originally developed to deform the polymer film to give it favorable structural properties, the SELF conversion process includes an air-laid absorbent core as disclosed herein. It has been found that it can be used to create advantageous structures in non-woven webs, which are useful as absorbent core materials.

Reference to FIG. 6 shows the configuration of the opposing molding rolls used in the SELF process, where the SELF process is a portion of the non-woven web by expanding a portion of the web out of the XY plane in the Z direction. Can be adopted to increase the web thickness dimension of. As shown in FIG. 7, the unmodified non-woven web 34 can be fed from the feed roll 36 into the nip 38 of the opposing molding rolls 62 and 64. Similar to those described for rolls 40 and 42 above, roll 64 includes a plurality of peripheral ridges 52 and grooves 54 that extend in the circumferential direction and are axially spaced apart. The roll 62 includes a plurality of peripheral ridges 52 extending in the circumferential direction and separated in the axial direction, and a part of the peripheral ridges 52 of the roll 62 defines a plurality of teeth 68 separated in the peripheral direction. It has been removed to form a notch 66. As shown in FIG. 6, the notches 66 on the respective peripheral ridges 52 adjacent in the axial direction are laterally aligned, and a plurality of notch areas separated in the peripheral direction are placed around the roll 62. Can be defined along. Each of the laterally extending notch areas extends parallel to the axis of the roll 62. The tooth 68 may have a tooth height TH corresponding to the ridge height RH and a tooth pitch matching the ridge pitch P.

As the web 34 passes through the nip 38, the teeth 68 on the roll 62 push a portion of the web 34 out of the plane, causing a permanent local deformation of the web 34 in the Z direction. However, the portion of the web 34 that passes between the notch area 66 of the roll 62 and the teeth 68 of the roll 62 is substantially unformed in the Z direction, i.e. the non-woven web is of the serrated area in this area. A portion of the web that passes between the serrated area of roll 62 and the ridge 52 of roll 64 is a non-woven fabric, while it is not deformed or stretched to the same extent as one and can remain substantially flat. A plurality of raised rib-like elements that are deformed or stretched beyond the elastic limit of the deformed can be generated.

Here, with reference to FIG. 8, a schematic representation of a portion of the SELF-ized non-woven web 70 after passing between a pair of interconnected opposing molding rolls 62 and 64 of the SELF process is shown. These rolls have a tooth structure similar to that shown in FIG. The SELF-ized non-woven web 70 includes a reticulated structure consisting of separate areas. This network includes at least a first zone 72, a second zone 74, and a transition zone 76 at the boundary between the first zone 72 and the second zone 74. The SELF-ized non-woven web 70 also has a first surface 78 and a second surface 80 facing the opposite side. In the embodiment shown in FIG. 8, the SELF-ized non-woven web 70 includes a plurality of substantially flat separated first zones 72 and a plurality of alternating rib-like elements 84. In a preferred embodiment of FIG. 8, the first zone 72 and the second zone 74 are substantially linear, each extending continuously in a direction substantially parallel to the longitudinal axis of the web. ..

In the embodiment shown in FIG. 8, the first zone 72 is substantially planar. That is, the material in the first zone 72 is substantially flat, and after the non-woven web 60 has been subjected to a denaturing step by passing between the interconnected rolls 62 and 64 shown in FIG. It is in substantially the same state as before the web 34 was passed between the molding rolls.

In the air-laid absorbent core, the rib-like elements 84 can be beneficial adjacent to each other and can be separated from each other by an unmolded first zone 72, which is the adjacent rib-like element. It has been found that the valley portion 86 that separates 84 can be included. The unmolded first zone 72 can be a region that has substantially the same material properties as the homogeneous air-laid absorbent core before SELF formation and is approximately measured perpendicular to the X-axis shown in FIG. It can have a width of less than 0.25 cm (0.10 inch). If desired, the dimensions of the rib-like element can also be changed. The rib-like elements that project in the Z direction with respect to the plane of the web are raised portions, which increase its bulk or caliper without necessarily increasing the basis weight of the web. The raised portion also defines a continuous network of channels within the unmolded first zone 72, which are combined with the web to form a layered absorbent core, for example for disposable absorbent products. If so, define a hollow area between the surface of the web and any adjacent web. In one embodiment, the continuous network of channels may define a hollow area adjacent to the topsheet. Hollow areas can help provide void capacity within the absorbent core so that the absorbent core has greater permeability and can more effectively handle the "spout" of fluid. The continuous network of interconnected channels has channels running in both MD and CD directions within the plane of the absorptive core. The channel can facilitate the lateral "flow" of the fluid so that it can be more effectively distributed over the length and width of the absorbent core.

In one embodiment, the non-woven web processed by the SELF process described herein can be a web having absorbency properties suitable for use as an absorbent core in a disposable absorbent article. In one embodiment, the web can be an air-laid web of fibers, including cellulose fibers, synthetic fibers, and blends and combinations thereof. In one embodiment, the air-laid web can be a layered air-laid web formed from multiple layers, each layer being different from adjacent layers in terms of fiber type, density, basis weight, or combination thereof. .. In one embodiment, the absorbent core material in which the rib-like elements are formed can be used in a layered relationship with the topsheet, in which case the rib-like elements are oriented towards the topsheet. At the same time, it is in contact with the top sheet. In one embodiment, the absorbent core material in which the rib-like element is formed can be used in a layered relationship with the second topsheet, in which case the rib-like element is on the second topsheet. It is oriented toward and is in contact with the second top sheet. The second topsheet can be what is commonly referred to as the partitioning layer, which can be an absorbent material with fluid processing properties suitable for rapidly distributing the fluid laterally. Alternatively, in another embodiment, the rib-like element can be used in a layered relationship with the top sheet or second top sheet, in which case the rib-like element is separated from the top sheet or second top sheet. And not in contact with the top sheet or the second top sheet.

Illustrated in FIG. 8 in the form of rib-like elements, each having substantially equal length and arranged in rows, defining a generally rectangular deformation region separated by a linear first zone 72. In addition to the surface pattern, the formation of the desired non-woven web can be brought about by the tooth and groove configurations of other molding rolls, which can, if desired, cause local elongation and / or deformation of the non-woven material. For example, as shown in FIG. 10, instead of an array of spaced rectangular rib-like elements, the deformation pattern defines an array of interleaved rhombic second areas 74 with the undeformed first area 72 intervening. Can be in the form of rib-like elements. Each such diamond-shaped second zone 74 is defined by alternating rib-like elements 84 and intervening valley portions 86. Examples of methods and devices for forming such rhombic elements are described in US Pat. No. 5,650,214, entitled "Sheet Materials Exhibiting Elastic-Like Behavior and Soft. , Cloth-Like Texture "(Barry J. Anderson. Anderson)) et al., Published July 22, 1997), and US Pat. No. 6,383,431, entitled "Method of Modifying a Nonwoven Fiberous Web For". Use as a Component of a Disposable Absorbent Article (Dobrin et al., May 7, 2002).

As shown in FIG. 10, the deformation pattern can also be in the form of rib-like elements 84 that together define an array of separated circular second zones 74. Each such circular element can be defined by rib-like elements 84 of various lengths and intervening valleys 86 that are appropriately spaced. Between each circular element 108 is an intervening unmolded first zone 72. Other variations, such as those exemplified and described in US Pat. No. 5,518,801, may be employed if desired, as will be apparent to those skilled in the art.

A third means for transforming the web of the present invention is the process best described as "micro SELF". Micro SELF is a process similar to the equipment and methods of the SELF process described with respect to FIGS. 6 and 7. The main difference between SELF and micro SELF is the size and dimensions of the teeth 68 of the serrated roll (ie, the micro SELF roll 82 in FIG. 11 corresponding to roll 62 in FIG. 6). A schematic side view of the micro SELF roll 82 is shown with reference to FIG. 11, where the micro SELF roll 82 is shown as one patterned roll, eg, the micro SELF roll 82, and roll 64 in FIG. It may be one of the rolls forming the nip roll configuration, with a preferred configuration having one non-patterned grooved roll (not shown) similar to. However, in certain embodiments, it may be preferable to use two microSELF rolls 82 with the same or different patterns in the same or different corresponding areas of each roll. Such a device can produce a web with deformation in a non-woven web that can be described as a tuft or loop protruding from one or both sides of the web being processed. The tufts can be closely separated, but at least at their base, a hollow area can be defined between the tufts and separated enough to allow fluid to flow between adjacent tufts. Those present between the tufts can define a continuous network of channels. In the micro SELF roll of Figure 11, each tooth 68 has a tooth length TL of about 1.27 mm (about 0.051 inch), an interdental distance TD of about 1.57 mm (about 0.062 inch), and about 1.52 mm (about 0.060). Can have a pitch of inches). In one embodiment, around the roll 82, there may be 158 teeth 68 separated by 159 cuts between the teeth 68.

As shown in the partial perspective view of FIG. 12 and the enlarged partial perspective view of FIG. 13, the teeth 68 of the micro SELF roll 82 have a specific geometric shape with respect to the front and trailing edges of the teeth 68, thereby. The teeth are essentially capable of "punching" the non-woven web 34, as opposed to deforming the web into protrusions or ridges as shown in FIGS. 8-10. In some embodiments of the non-woven web 34 suitable for use in absorbent cores, the teeth 68 urge the fibers out of plane so that they can be described as "tufts" or loops of fibers. Form. In one embodiment, the web is punctured, so to speak, by pushing the teeth 68 through the fibers to form a tuft or loop. Thus, unlike the "tent-like" rib-like elements of the SELF web, each of which associates a continuous side wall, i.e. has a continuous "transition region", a tuft or loop extruded out of the plane in the microSELF process. Can have a discontinuous structure of Z-direction deformed portions with respect to the side wall portions. In addition, when used in relatively high basis weight absorbent core materials, "tufting" can be somewhat invisible, but it is because the fibers are out of plane in the Z direction with respect to one of the web surfaces. This is because the Z-direction deformed portion may be weakened or absent on the other web surface. In addition, when laminated material is included, the Z-direction deformation of one web material may be pushed in and "hidden" by the second material of the laminate, thereby making "tufting" essentially the naked eye. I can't see it.

As shown in FIGS. 12 and 13, each tooth 68 has a tooth tip 112, a leading edge LE, and a trailing edge TE. The tooth tip 112 is elongated and generally oriented in the longitudinal direction. It is believed that LEs and TEs should be approximately orthogonal to the local peripheral surface 90 of the roll 80 in order to obtain tufted, looped tufts in the processed web. Similarly, the transition from the tip 112 and LE or TE is like a right angle with a sufficiently small radius of curvature such that the tooth 68 is pushed through the web 34 with LE and TE (as shown in FIG. 14). Should be sharp. Without being bound by theory, the tooth 68 "cleanly" or locally and clearly punches the non-woven web when it has a relatively sharp tip transition between the tip 112 of the tooth 68 and LE and TE. It is believed that this will be possible, and as a result, one side of the resulting web can be described as "tufted" or "transformed".

The tooth 68 of the micro SELF roll 82 can have a uniform peripheral length dimension TL that is generally measured from the front edge LE to the trailing edge TE at the tooth tip 112 of about 1.25 mm and is perimetered by a distance TD of about 1.5 mm. Evenly separated from each other in the direction. To process a web with a total basis weight in the range of about 30 to about 500 gsm, the teeth 110 of the roll 104 have a length TL in the range of about 0.5 mm to about 3 mm, and about 0.5 mm to about 3 mm. It can have a spacing TD, a tooth height TH in the range of about 0.5 mm to about 5 mm, and a pitch P of about 1 mm (0.040 inch) to about 6.4 mm (0.250 inch). The engagement depth E can be from about 0.5 mm to about 5 mm (up to equal tooth height TH). Of course, E, P, TH, TD and TL can be modified independently of each other to achieve the desired dimensions, spacing and areal density of the web deforms.

A fourth means for deforming a web suitable for use as an absorbent material is the process best described as "rotary knife aperturing" (RKA). RKA utilizes processes and equipment using meshing nip rolls 92 that rotate in opposite directions, similar to those described above for SELF or micro SELF rolls, as shown in FIG. As shown, the RKA process differs from SELF or micro SELF in that the relatively flat, elongated teeth of the SELF or micro SELF roll are modified to be generally pointed at the distal end. The teeth 68 can be sharpened to cut and deform the non-woven web 34, as shown in FIG. 14, to produce a three-dimensional perforated web 94. In other respects, such as tooth height, tooth spacing, pitch, engagement depth, and other processing parameters, the RKA and RKA devices can be identical with respect to SELF or micro SELF as described above.

FIG. 15 shows a portion of an embodiment of an RKA serrated roller with a plurality of teeth 68 that is useful for making a perforated web 94. An enlarged view of tooth 68 is shown in FIG. As shown in FIGS. 15 and 16, each tooth 68 has a base 111, a tooth tip 112, a leading edge LE and a trailing edge TE. The tooth tip 112 is generally sharpened, bluntly pointed, or otherwise shaped to extend and / or puncture the precursor web 34. The teeth 68 may have a generally flat blade-like shape. Teeth 68 may have distinct side surfaces 114 that are generally flat. That is, in contrast to a round pin shape with a generally rounded cross section, the tooth 68 may have an elongated cross-sectional feature that is elongated in one dimension and is generally unrounded. For example, at its base, the tooth 110 exhibits a tooth aspect ratio AR of at least 2, or at least about 3, or at least about 5, or at least about 7, or at least about 10, or more TL / TW. Can have a length TL and a tooth width TW. In one embodiment, the aspect ratio AR of the cross-sectional dimensions remains substantially constant regardless of tooth height.

In one embodiment of the RKA serrated roll, the tooth 68 has a uniform peripheral length dimension TL of about 1.25 mm, approximately 1.25 mm measured from the front edge LE to the trailing edge TE at the base 111 of the tooth 110, and the periphery at the base. It can have a tooth width TW of about 0.3 mm, which is the longest dimension measured approximately perpendicular to the length dimension. The teeth can be evenly spaced from each other in the circumferential direction at a distance TD of about 1.5 mm. To make a flexible fibrous three-dimensional perforated web from a precursor web 20 having a basis weight in the range of about 5 gsm to about 500 gsm, the tooth 68 has a length TL in the range of about 0.5 mm to about 3 mm. , Approximately 0.3 mm to approximately 1 mm tooth width TW, and approximately 0.5 mm to approximately 3 mm spacing TD, approximately 0.5 mm to approximately 10 mm tooth height TH, and approximately 1 mm (0.040 inch) to 2.54 mm ( It can have a pitch P of 0.100 inch). The engagement depth E can be from about 0.5 mm to about 5 mm (up to tooth height TH).

Of course, DOE, P, TH, TD and TL are each modified independently of each other, with the desired dimensions, spacing and area density of the openings (apertured three-dimensionally). The number of apertures per unit area of apertured)) can be achieved. For example, the tooth length TL at the base can range from about 2.032 mm to about 3.81 mm to make perforated films and non-woven fabrics suitable for use in sanitary napkins and other absorbent articles. The tooth width TW can be in the range of about 0.508 mm to about 1.27 mm, the tooth spacing TD can be in the range of about 1.0 mm to about 1.94 mm, and the pitch P can be in the range of about 1.106 mm to about 2.54 mm. And the tooth height TH can be from about 2.032 mm to about 6.858 mm. The engagement depth DOE can be from about 0.5 mm to about 5 mm. The radius of curvature R of the tooth tip 112 can be 0.001 mm to about 0.009 mm. Without being bound by theory, the tooth length TL at the base can range from about 0.254 mm to about 12.7 mm and the tooth width TW can range from about 0.254 mm to about 5.08 mm. The tooth spacing TD can range from about 0.0 mm to about 25.4 mm (or more), the pitch P can range from about 1.106 mm to about 7.62 mm, and the tooth height TH can be 0.254. It is believed that it can range from mm to about 18 mm, and the depth of engagement E can range from 0.254 mm to about 6.35 mm. For each of the disclosed ranges, it is disclosed herein that the dimensions can be changed in increments of 0.001 mm within the range of minimum to maximum dimensions, and this disclosure is in the range limits and in between. It is disclosed herein that the dimensions are taught in 0.001 mm increments (excluding the radius of curvature R disclosed as the increments vary in 0.0001 mm increments).

RKA teeth can have other shapes and contours, and the RKA process is a simultaneous pending patent application of the same owner US Patent Application Publication No. 2005/0064136 (A1) (filed August 6, 2004), As disclosed in US Patent Application Publication No. 2006/0087053 (A1) (filed October 13, 2005) and US Patent Application No. 2005/021753 (filed June 21, 2005) on the Textile Web. Can be used to make holes.

Each of the web deformation processes described above is known for processing various webs of absorbent articles in the art. For example, ring rolling) is a hole in combination with a heat melting weakening step, as disclosed in U.S. Pat. No. 5,628,097, U.S. Pat. No. 5,916,661, and U.S. Patent Application Publication No. 2003/0028165 (A1). It is known to be used to produce. Similarly, the SELF process is well known for making stretched portions of topsheets, as disclosed in US Patent Application Publication No. 2004/0127875 (A1) (filed December 18, 2002). Micro SELF rolls are as disclosed in US Patent Application Publication No. 2004/0131820 (A1), International Publication No. 2004/059061 (A1), and International Publication No. 2004/058118 (A1). It is known to produce beneficially modified topsheets. RKA is also known to produce perforated molded films, non-woven webs, and laminates, as disclosed in US Patent Application No. 2005/021753. The absorbent core has also been modified by microSELF rolls, as disclosed in WO 2004/058497 (A1), where the two webs were processed together to integrate the fibers. By forming a composite absorbent core, a laminate of two webs is created.

In each of the processes described above, heat can be utilized by heating the web in front of the roller nip or by a heating roller, or by heating the web after leaving the nip roller. Care must be taken to consider thermal expansion when heating any of the rollers of the above equipment. In one embodiment, the dimensions of the ridges, grooves, and / or teeth are machined in consideration of thermal expansion so that the dimensions described herein can be dimensions at working temperature.

In one embodiment, the processing of the absorbent core material is carried out by the same owner, co-pending US Patent Application No. 2006/0286343 (A1), entitled "Tufted Fiber Web (Tufted). It can be achieved by the methods disclosed in Fibrous Web). The method can include heating means capable of heating and / or coupling the tip or distal end of a web mechanism such as a rib or tuft. Such heating and / or coupling can increase the compressive resistance of the absorbent core and also improve its elasticity, which is important for maintaining permeability under pressure. Elasticity can be improved by incorporating a thermoplastic binding powder, such as polyethylene powder, into the fiber web and then heating within the area where the binding is desired. Elasticity can also be improved by applying a coating, such as a latex coating that tends to cure the fibers.

In one embodiment, the plurality of absorbent core layers can be integrated by entwining fibers from adjacent webs with each other. Entanglement of fibers in adjacent layers can be achieved by the processes described herein and by known means such as needle punching, water flow entanglement, and heat point coupling. By this same process and means, it may be desirable to integrate the topsheet of the absorbent article with a lower layer, eg, a second topsheet modified by the process disclosed herein.

Although the various web deformation processes described above are known for topsheets, backsheets, and composite absorbent cores, the novel mechanism of the invention achieves unexpected results in fluid processing properties in homogeneous absorbent webs. These processes are applied in order to make the homogeneous absorbent web individually processed to be inhomogeneous, and then processed to be inhomogeneous by the web deformation process as well. Combined in a layered relationship with the web. The combined webs do not need to be fixed in a bonded relationship and, if desired, are bonded by means known in the art such as adhesive bonding, thermal bonding, fiber entanglement, latex bonding, and combinations thereof. can do. The present invention relates to bicomponent fibers, nanofibers, molded fibers, and a wide variety of fibers including combinations thereof, as well as wet webs including melt blown, spunbond, and card web, tissue paper, or a combination of these processes. It is believed that it can be applied to a wide variety of webs by various formation processes including. The present invention will be described later in certain embodiments of air-laid absorbent fiber webs, i.e., core materials made by the air-laying process.

Air laying is the process for making non-woven webs, where the cut short fibers are introduced into the air stream, thereby pushing the fibers onto a laydown belt in a controlled manner. The fibers may be natural or synthetic, or may be combined by thermal, chemical, or mechanical means into an integrated non-woven web. Short fibers with cut fibers (stable) When fed in a compacted form as fibers), the airlaid process initiates a defibrillation system that opens the short fibers and feeds them into the air stream. Other functions can also be performed, such as administration and introduction of superabsorbents or other powders. The fibrous material and / or other material is suspended in the air inside the forming system and subsequently deposited on a moving forming screen or rotating perforated cylinder to form a randomly oriented air forming vat. To do. The air forming vat can be bonded by applying a latex binder and drying, thermally bonding the thermoplastic short fibers in the web, hydrogen bonding or embossing, or a combination of these integration techniques. The formation of air-laid webs is taught in US Pat. No. 4,640,810 (Laursen et al.). Air-laid webs can be made by air-laying a blend of fibrous materials, or by air-laying different types of fibers, or by air-laying separate layers with a blend of fibers.

In general, known methods of making airlaid materials produce a homogeneous web of airlaid materials. As used herein, "homogeneity" refers to the uniformity of the web in the MD-CD plane, for example, as shown in FIG. Prior to forming through the nip 38, as shown in FIG. 14, the web 34 is typically such that the web is substantially uniform in bulk properties such as density and basis weight in the MD-CD plane. It can be formed by an air-laid process. Virtually every separate area selected within the MD-CD plane of the homogeneous web will have the same material processing properties as the directly adjacent area. Note that "homogeneity" does not refer to the properties of the web in the "Z direction", which can be considered the thickness of the web, that is, in the direction perpendicular to the MD-CD plane. Web properties in the Z direction can be altered by layering the fibers in a non-uniform way throughout the thickness of the web.

As used herein, "heterogeneity" refers to the inhomogeneity of the web in the MD-CD plane, for example, as shown in FIG. As shown in FIG. 14, after being formed through the nip 38, the web 34 is heterogeneous and the web is substantially incompatible in bulk properties such as density and basis weight in the MD-CD plane. It is uniform. A separate area of the web is mechanically transformed into a tuft, opening, or other three-dimensionally formed structure, whereby separate parts of the web in the MD-CD plane are directly adjacent areas. Will have completely different material processing properties.

The dimensions of the separate parts under consideration can be varied depending on the dimensions of the web and the purpose of the heterogeneous web. However, in general, it is desirable to have separate parts that are closely spaced at about 1 to about 30 square centimeters, including all intermediate integers, including about 5 to about 10 per square centimeter. For example, by having separate parts that are relatively closely spaced (in the MD-CD plane) in the form of ribs, tufts, or openings, fluid processing allows a given drop of fluid on the web to be with the web. It is ameliorated by increasing the probability of experiencing both high permeability and high capillary action options upon contact.

To illustrate the invention, a generally homogeneous absorbent airlaid fiber web material is modified by one or more of the four processes described above and used in a sanitary napkin in a safe storage compartment within the absorbent core. A non-homogeneous absorbent core material has been achieved that has the ability to move fluids rapidly and favorably. In one aspect, the heterogeneity of the absorbent core allows the core to exhibit fluid transfer properties approximately laterally, i.e. in the plane of the web material. That is, rather than exhibiting inhomogeneity in the Z direction, i.e. through the thickness of the web, the web of the invention is in the "XY" plane, i.e. parallel to the plane of the web in a generally flat state. In a plane, it is possible to exhibit inhomogeneity, which is referred to herein as lateral fluid movement.

Tables 1 and 2 below illustrate the effect of processing airlaid fibrous absorbent materials by one or more of the four forming means described above. For all dimensions, 1 inch is equal to 25.4 mm.

Table 1 shows the changes in fluid processing properties for the web, referred to herein as Absorbent Core I, made from the unmodified precursor webs listed in Table 1 as Control Absorber I. The web of Control Absorber I has a basis weight of approximately 180 grams (gsm) per square meter and contains cellulose fibers and bicomponent fibers blended with 30 gsm of absorbent gel material (AGM) in the air laying process. , Airlaid absorbent core material. The cellulose fiber is Weyco NB416 obtained from Weyerhaeuser Co. The bicomponent fiber is Invista # 35160A (PE / PET, 2.0 denier and 4 mm long) obtained from Invista, with a cellulose fiber to bicomponent fiber ratio of 5 grams to 1 gram. .. The AGM is Degussa 23070G obtained from Degussa and is distributed substantially evenly throughout the web. Air Products (Air) Approximately 5% by weight of latex AF192 obtained from Products) is sprayed on both surfaces and cured.

Table 2 shows the changes in fluid processing properties for the web, referred to herein as Absorbent Core II, made from the unmodified precursor webs listed in Table 1 as Control Absorber II. Control Absorber II is an air-laid absorbent material suitable for use as a second topsheet, a laminate with a basis weight of approximately 82 grams (gsm) per square meter. One layer of the laminate of Control Absorber II is a hydrophilic non-woven fabric of spunbonded polypropylene (PP) having a basis weight of about 22 gsm. The spunbond web layer is available as P9 from Fiberweb. The spunbonded polypropylene web is laminated on the web produced in the air laying process, and the air laid web is a 60 gsm web of cellulose fibers and a polyethylene powder binder blended in the air laying process. Approximately 5% by weight of latex AF 192 obtained from Air Product was sprayed onto the surface of the air-laid web prior to stacking on the spunbond material. Cellulose fiber is Weyerhaeuser It is a Weyco NB416 obtained from Co.). The polyethylene powder binder is Dow Low Density polyethylene 959s obtained from Dow, with a cellulose fiber to polyethylene powder binder ratio of 3 g to 1 g. After air laying, the laminated web is processed through a heating step to affect the binding properties of the polyethylene binder powder.

As shown in Table 1, absorption and desorption capillary pressure, grams per gram capacity, permeability, and flow rate are all beneficially positive by forming in the presented process. Can be changed in any way. Each parameter was measured by the tests shown in the test method chapter below.<tables num="1"><img file="JP2010520005A_D0001.tif" /></tables>

Sample No. 2 was prepared by processing Control Absorber I through a SELF conversion process in which the serrated roll had the dimensions shown in FIGS. 17-20. As shown in FIG. 19, the teeth had a pitch P of 2.54 mm (0.100 inches), a tooth height TH of about 6.86 mm (about 0.270 inches), and a tooth angle TA of about 9.487 degrees. .. As shown in Figure 20, each tooth has a tooth length of about 5.33 mm (about 0.2101 inches), a tooth spacing of about 1.98 mm (about 0.0781 inches), and a tooth opening angle of about 2.903 degrees. It had a (diverging tooth angle) DA. The meshing roll is a non-sawtooth roll, ie, a peripherally extending ridge and groove that engages with a DOE of approximately 1.78 mm (approximately 0.070 inch), similar to that shown in Figure 6 above. It was a roll to have. The SELF process was performed at room temperature at a rate of about 1-5 m / min.

Sample No. 3 was prepared by processing Control Absorber I through a SELF conversion process in which the serrated roll had the dimensions shown in FIGS. 21-23. FIG. 21 is a flattened view of the perimeter of the serrated roll. One difference between the tooth composition of the roll shown in FIGS. 21-23 and that used to make sample 2 is that the teeth are viewed from the top (ie, in a plan view overlooking the surface of the roll). At that time, each tooth does not have a substantially rectangular shape, but has a substantially rhombic shape as shown in FIG. 23. In addition, the tooth-to-tooth pitch P arranged in a row is 5.08 mm (0.200 inch), and as a result, the staggered pattern tooth-to-tooth pitch P is 0.100 pitch P. Tooth 68 has a tooth length TL of about 5 mm and a tooth distance TD of about 4 mm. The meshing roll is a non-sawtooth roll, i.e., a roll with ridges and grooves extending in the circumferential direction, similar to that shown in FIG. 6, and the two meshing rolls are about 1.78 mm ( It meshed with a DOE (about 0.070 inch). The SELF process was performed at room temperature at a rate of about 1-5 m / min.

Sample No. 4 was prepared by processing Control Absorber I through an RKA process in which the serrated roll had teeth with the dimensions shown in FIGS. 24-27. As shown in FIGS. 24-27, the teeth of the serrated RKA roll consisted of a staggered pattern with an inter-row pitch P of about 2.54 mm (about 0.100 inches). Tooth 68 has a tooth length TL (measured at the base) of about 3.81 mm (about 0.150 inch) and a tooth distance TD of about 1.94 mm (about 0.076 inch). As shown in FIG. 26, tooth 68 has a tooth width at a base of about 1.27 mm and a tooth height TH of about 6.858 mm (about 0.270 inches). The meshing roll is a non-sawtooth roll, ie, a peripherally extending ridge and groove that engages with a DOE of approximately 6.35 mm (approximately 0.250 inches), similar to that shown in Figure 6 above. It was a roll to have. The RKA process was performed at room temperature at a rate of about 1-5 m / min.

Sample 5 was prepared by processing Control Absorber I through a SELF conversion process in which the serrated roll had the configuration shown in FIGS. 28-30. The teeth 68 are staggered with three teeth that are generally circular in order to form a pattern similar to that shown in FIG. 10 on the processed web rather than a straight row across the width of the roll. Are arranged as a group of. As shown in FIG. 30, tooth 68 has a tooth height TH of about 3.6 mm (0.145 inches) and a pitch P of about 1.524 mm (about 0.060 inches). The serrated roll engages with a DOE of about 1.9 mm (about 0.075 inches), a meshing ring with fully sintered ridges and grooves similar to those shown in Figure 6 above. Engaged with the roll. The SELF process was performed at room temperature at a rate of about 1-5 m / min.

Sample 6 was prepared by processing Control Absorber I through a modified SELF conversion process, where the upper serrated roll had the configuration described for the serrated roll of Sample 5. However, the meshing (interacting) rolls do not have fully sintered ridges and grooves, similar to those shown in FIG. 6 above, as shown in FIGS. 11-13. Another serrated micro-SELF roll, similar to the one shown, had a pitch of about 1.52 mm (about 0.060 inch) to fit with the upper serrated roll. The roll was run with a DOE of about 1.65 mm (about 0.065 inch). This process was performed at room temperature at a rate of about 1-5 m / min.

As can be seen in Table 1, in all cases, the number of absorbed grams per gram (of the absorbent material), permeability and flow rate are all similar to the increase in capillary pressure in most cases. Significantly increased. All these improvements are simply the result of processing the web material through the nip of a pair of meshing (or interlocking) rollers as described above. Therefore, there are no new material contents or new compositions that increase costs with better fluid acquisition properties.<tables num="2"><img file="JP2010520005A_D0002.tif" /></tables>

Sample No. 8 was made by processing Control Absorber II through a ring rolling device as described with reference to FIGS. 2 and 3. The ring rolls had a pitch of about 1.016 mm and were meshed with a DOE of about 1.016 mm. This process was carried out at room temperature.

Sample 9 was prepared by processing Control Absorber II with a DOE of approximately 2.45 mm (approximately 0.100 inch) through the meshing SELF rollers described for Sample 2 above. The spunbonded PP side of control absorber II was directed to the non-sawtooth roll of the device. This process was carried out at room temperature.

Sample 10 is processed with Control Absorber II with a DOE of approximately 1.9 mm (approximately 0.075 inch) through a meshing micro SELF roller with a pitch P of approximately 1.52 mm (approximately 0.060 inch) as described with respect to FIG. Made by. The spunbonded PP side of control absorber II was directed to the non-sawtooth roll of the device. This process was carried out at room temperature.

Sample 11 is processed by processing Control Absorber II with a DOE of approximately 3.43 mm (approximately 0.135 inch) through a meshing micro SELF roller with a pitch of approximately 1.52 mm (approximately 0.060 inch) as described with respect to FIG. Made. The spunbond PP side of control absorber II was directed to the serrated micro SELF roll of the device. This process was performed at a temperature of 149 degrees Celsius (300 degrees Fahrenheit).

Sample 12 was prepared by processing Control Absorber II through an RKA process in which the serrated roll had teeth with the dimensions shown in FIGS. 31-34. The spunbond PP side of control absorber II was directed to the RKA roll of the device. As shown in FIGS. 31-34, the teeth of the serrated RKA roll consisted of a staggered pattern with an inter-row pitch of about 1.016 mm (about 0.040 inch). Each of the tooth height TH and the tooth length TL was about 2.032 mm (about 0.080 inch). The tooth distance TD was about 1.626 mm (about 0.64 inch) and the tooth width TW was about 0.510 mm (about 0.020 inch). Other dimensions were as shown in the figure. The meshing roll is a non-sawtooth roll, i.e., a roll with a DOE of about 6.35 mm (about 0.250 inches), with ridges and grooves extending in the circumferential direction, similar to that shown in Figure 6 above. there were. The RKA process was performed at a temperature of 121 degrees Celsius (250 degrees Fahrenheit) at a rate of about 1-5 m / min.

Sample 13 was prepared by processing Control Absorber II through an RKA process in which the serrated roll had teeth with the dimensions shown in FIGS. 35-38. The spunbond PP side of control absorber II was directed to the RKA roll of the device. As shown in FIGS. 35-38, the teeth 68 of the serrated RKA roll consisted of a staggered pattern with an inter-row pitch P of about 1.524 mm (about 0.060 inch). The tooth height TH was about 3.683 mm (about 0.145 inches), the tooth distance TD was about 1 mm (about 0.039 inches), and the tooth length TL was about 2.032 mm (about 0.080 inches). Other dimensions were as shown in the figure. The meshing roll is a non-sawtooth roll, i.e., a roll with a DOE of approximately 3.43 mm (approximately 0.135 inches), with ridges and grooves extending in the circumferential direction, similar to that shown in FIG. 6 above. there were. The RKA process was performed at a temperature of 149 degrees Celsius (300 degrees Fahrenheit) at a rate of about 1-5 m / min.

Sample 14 was prepared by processing Control Absorber II through an RKA process in which the serrated roll had teeth with the dimensions shown in FIGS. 24-27 above. The spunbond PP side of control absorber II was directed to the RKA roll of the device. The meshing roll is a non-sawtooth roll, i.e., a roll with a DOE of about 6.35 mm (about 0.250 inches), with ridges and grooves extending in the circumferential direction, similar to that shown in Figure 6 above. there were. The RKA process was performed at a temperature of 177 degrees Celsius (350 degrees Fahrenheit) at a rate of about 1-5 m / min.

Sample 15 was prepared by processing Control Absorber II through an RKA process in which the serrated roll had teeth with the dimensions shown in FIGS. 24-27 above. The spunbond PP side of control absorber II was directed to the RKA roll of the device. The meshing roll is a non-sawtooth roll, i.e., a roll with a DOE of about 6.35 mm (about 0.250 inches), with ridges and grooves extending in the circumferential direction, similar to that shown in Figure 6 above. there were. The RKA process was performed at room temperature at a rate of about 1-5 m / min.

Sample 16 was prepared by processing Control Absorber II through a SELF process in which the serrated roll had teeth with the dimensions described for Sample 5 above. The spunbond PP side of control absorber II was directed to the SELF roll of the device. The meshing roll is a non-sawtooth roll, i.e., a roll with a DOE of about 1.9 mm (about 0.075 inches), with ridges and grooves extending in the circumferential direction, similar to that shown in FIG. 6 above. there were. This process was performed at room temperature at a rate of about 1-5 m / min.

Sample 17 was prepared by processing Control Absorber II through a SELF process in which the serrated roll had teeth with the dimensions described for Sample 5 above. The spunbond PP side of control absorber II was directed to the SELF roll of the device. The meshing roll is a non-sawtooth roll, i.e., a roll with a DOE of about 1.9 mm (about 0.075 inches), with ridges and grooves extending in the circumferential direction, similar to that shown in FIG. 6 above. there were. This process was performed at a temperature of 149 degrees Celsius (300 degrees Fahrenheit) and a rate of about 1-5 m / min.

Sample 18 was prepared by processing Control Absorber II through a SELF process in which the serrated roll had teeth with the dimensions described for Sample 5 above. The spunbond PP side of control absorber II was directed to the SELF roll of the device. The meshing roll is a non-sawtooth roll, i.e., a roll with a DOE of about 1.65 mm (about 0.065 inch), with ridges and grooves extending in the circumferential direction, similar to that shown in FIG. 6 above. there were. This process was performed at room temperature at a rate of about 1-5 m / min.

Sample 19 was prepared by processing Control Absorber II through two separate, interconnected rollers. First, Control Absorber II was processed at room temperature through a ring roller nip with a pitch of about 1.016 mm and a DOE of about 1.016 mm. The ring-rolled web was then processed through an RKA process in which the serrated roll had teeth with the dimensions shown in FIGS. 31-34. The meshing roll is a non-sawtooth roll, i.e., a roll with a DOE of about 1.143 mm (about 0.045 inches), with ridges and grooves extending in the circumferential direction, similar to that shown in Figure 6 above. there were. The RKA process was performed at a temperature of 104 degrees Celsius (220 degrees Fahrenheit) at a rate of about 1-5 m / min.

Sample 20 was prepared by processing Control Absorber II through two separate, interconnected rollers. First, Control Absorber II was processed at room temperature through the nip of a micro SELF roller with a pitch of about 1.524 mm (about 0.060 inch) and a DOE of about 1.9 mm (about 0.075 inch). The spunbond PP side of control absorber II was directed to the ring roll (non-sawtooth roll) of the device. The micro-SELFed web was then processed through an RKA process in which the serrated roll had teeth with the dimensions shown in FIGS. 31-34. The spunbond PP side of control absorber II was directed to the RKA roll of the device. The meshing roll is a non-sawtooth roll, i.e., a roll with a DOE of about 2.16 mm (about 0.085 inches), with ridges and grooves extending in the circumferential direction, similar to that shown in Figure 6 above. there were. The RKA process was performed at a temperature of 149 degrees Celsius (300 degrees Fahrenheit) at a rate of about 1-5 m / min.

Sample 21 was prepared by processing Control Absorber II through two separate, interconnected rollers. First, Control Absorber II was processed at room temperature through the nip of a micro SELF roller with a pitch P of about 1.52 mm (about 0.060 inch) and a DOE of about 1.9 mm (about 0.075 inch). The spunbond PP side of control absorber II was directed to the ring roll (non-sawtooth roll) of the device. The micro-SELFed web was then processed through an RKA process in which the serrated roll had teeth with the dimensions shown in FIGS. 24-27. The spunbond PP side of control absorber II was directed to the RKA roll of the device. The meshing roll is a non-sawtooth roll, i.e., a roll with a DOE of about 2.54 mm (about 0.100 inches), with ridges and grooves extending in the circumferential direction, similar to that shown in Figure 6 above. there were. The RKA process was performed at a temperature of 149 degrees Celsius (300 degrees Fahrenheit) at a rate of about 1-5 m / min.

As can be seen in Table 2, in almost all cases, the number of grams of absorption efficiency (of the absorbed fluid), the permeability and the flow rate per gram (of the absorbent material) are all with an increase in capillary pressure in most cases. It also increased significantly. All these improvements are simply the result of processing the web material through the nip of a pair of interlacing rollers as described above. Therefore, there are no new material contents or new compositions that increase costs with better fluid acquisition properties.

As shown in Tables 1 and 2 above, processing the air-laid web with the presented web deformation methods can have a beneficial immediate effect on the fluid processing properties of the web material. Without being bound by theory, this beneficial effect is due to the destruction of fibers at closely separated and distinct locations, thereby resulting in areas of low or high permeability, respectively. It is believed that a separate, but relatively close-separated area of high or low permeability (depending on the particular web deformation process) is created that is surrounded. For example, in the ring rolling example, the essence of this process is to produce a row of high density, high capillary material separated by a row of low density, low capillary material. Although it is recognized that ring rolling is well known in the art, the application of ring rolling to airlaid materials has new beneficial results in the field of absorbent core materials. It is considered to be a new application that brings about.

In addition to the benefits seen when individual webs are processed as shown in Tables 1 and 2, are the webs processed by one or more web transformation processes described above processed in the same way? Or when combined with other webs processed by different web transformation processes, in addition surprising and unexpected benefits can be realized. The present invention is particularly valuable in relation to sanitary napkins when one of the processed webs is used as the second topsheet and one of the webs is used as the absorbent core. The technical terms "second topsheet" and "absorbent core" are not limiting. That is, the second topsheet can also be considered to be an absorbent core, but the term used herein refers to a topsheet having the property of moving fluid away from the topsheet and into the absorbent core. As a material used adjacent to the topsheet below, it is used in its usual sense developed in the field of sanitary napkins. That is, the second topsheet may have absorbent properties but is not intended to retain the fluid, but to transfer the fluid to an absorbent storage medium, such as an absorbent core material. Yes, this absorbent core material is intended to reliably retain the fluid and ensure that it does not return to the wearer's skin.

The advantageous properties of the present invention can be illustrated with reference to Table 3. Table 3 shows the fluid processing properties of the web materials from Tables 1 and 2, i.e., various combinations of web materials that have been deformed by one or more of the processes described above. In Table 3, each combination of web materials from Tables 1 and 2 was tested in a configuration that mimics a sanitary napkin, and each sample was described in US Pat. No. 4,629,643 (Curro et al., 1986). The type of sanitary napkins of the ALWAYS® brand disclosed in (issued December 16), such as those marketed by The Procter &amp; Gamble Co. Tested using a perforated molded film web.

Therefore, for each sample in Table 3, the structure tested was a layered structure containing a perforated molded film topsheet, a second topsheet of core II (STS), and an absorbent core of core I in that order. .. Table 3 shows a particular airlaid fibrous structure by reference to each sample number in Tables 1 and 2 above.<tables num="3"><img file="JP2010520005A_D0003.tif" /></tables>

As shown in Table 3, the two-layer absorbent core of the present invention (as shown in Samples 23-33) has capillaries (as shown in rewetting pressure) compared to the control body (Sample 22). Break the trade-off between permeability vs. capillary pressure by achieving relatively higher permeability (as shown in free ejection flow, acquisition rate, and retention capacity) without significant reduction in pressure. be able to.

Used as an absorbent core in an absorbent product, the webs of the present invention exhibit properties that appear to have broken the trade-off between permeable vs. capillary pressure. Without being bound by theory, this apparent cutoff is believed to be due to the generation of effective structures that provide fluid processing properties in both trade-off regions. For example, the disclosed process has created separate locations for larger void volumes, which are believed to allow the core material to exhibit the desired effects of both properties, especially in multi-layered cores. Larger void volumes in fibrous materials can result in greater permeability. These larger permeable areas are relatively closely separated and separated by a non-denatured area of the web, which exhibits relatively low permeability but relatively high capillary pressure. Thus, fluids that collide with the core, such as menstrual blood absorbed through the topsheet of absorbent articles during use, offer the potential for both hydrodynamics, high permeability and high capillary pressure. The hydrodynamics of such cores can be, in effect, the result of utilizing the best of both material properties.

The material properties of the cores of the present invention, whether single or multiple cores, can be further enhanced by additional core layers, or additional material layers within a given core material. That is, for example, additional airlaid webs can be modified by the methods disclosed herein and added in a layered relationship with two or more other layers. Similarly, any one of the air-laid webs can itself be a layered structure that exhibits a Z-direction gradient of fluid processing properties. For example, with respect to any one of the absorbent cores disclosed herein, including the air-laid web, the cores are in the Z direction, from low density on one side of the web to relatively high density on the other side. Can exhibit a density gradient of. Similarly, permeability, capillary action, fiber types and dimensions, and other physical properties are within the layered web so that the Z-direction gradient of virtually any physical property of the web can be assumed to be useful in the present invention. Can be changed in various combinations.

In one embodiment of a layered absorbent core, such as a layered air-laid web, one layer is designed to be destroyed while the other layer (s) are not destroyed when processed by the process described herein. What you can do is considered. For example, the intermediate layer of a three-layer air-laid web can contain materials such as fibrous materials that are destroyed by low levels of strain, and when stressed by the methods described herein, the intermediate layer is destroyed. While forming separate isolated openings, the remaining layers are not destroyed. In a similar manner, one layer of a multi-layer web can be shredded.

In one embodiment of the layered absorbent core, it is considered that one or more of the multi-layers can form a laminate, which is a non-fibrous material such as foam or film web. For example, the absorbent core of the present invention may include or be combined with an absorbent foam material such as High Internal Phase Emulsion (HIPE) foam.

In one embodiment, degeneration patterns, such as those due to teeth on SELF rolls, can vary across the width of the denatured web. For example, rolls in the SELF process can be designed so that the tooth-groove pitch P varies across the width of the roll and, as a result, across the width of the web. In this method, for example, the central area that coincides with the longitudinal centerline area of the absorbent article may have a pattern of ridges, tufts, openings, or other mechanisms that differs from one or both side areas. , Absorbent core can be produced.

To illustrate the density changes, schematics of the two cores of the invention are shown in Figures 39 and 40. FIG. 39 shows a schematic representation of Sample 2 detailed above with respect to Table 1. FIG. 40 shows a schematic representation of Sample 10 detailed above with respect to Table 2. For both schematics, the Z-direction local deformation of the base web out of plane is displayed as a rectangle. The illustrated square is an approximate representation of the relative XY boundaries of the Z-direction deformed portion, where X and Y can coincide with the transverse direction (CD) and the mechanical direction (MD), respectively. The rectangles represent the "tent-like" rib-like elements of Sample 2 and the approximate representation of the Taft of Sample 10, each of which is at least about 1.5: 1, or 1.7: 1, or 2.0: 1, Or it can have a separate aspect ratio of 2.7: 1, or 3: 1, or 5: 1, or 10: 1, divided by width, for which any number from 1.5 to 10 is 10. Included in 1 / increment increments. The dimensions and shape of the rectangles, as well as the spacing between adjacent rectangles, can be created using visualization techniques, as is known in the art.

As shown in FIG. 39, the rib-like element represented as "a" can be about 5.5 mm long and about 2 mm wide. Each element can be separated from the adjacent element in the CD direction by an area labeled "b" which can be about 0.6 mm. Each element can be separated from the adjacent element in the MD direction by an area labeled "c" which can be about 1.3 mm. Density measurements of the various areas "a", "b", and "c" indicate that SELFization of non-woven webs such as fibrous airlaid webs can result in relatively low density out-of-plane deformations. .. In the embodiment depicted in FIG. 39, the base material has a density of about 0.221 g / cc, area "a" has a density of about 0.128 g / cc, and area "b" has a density of about 0.199 g / cc. The area "c" had a density of about 0.226 g / cc.

As shown in FIG. 40, the tuft element represented as "a" can be about 1.7 mm long and about 1 mm wide. Each tuft element can be separated from the adjacent element in the CD direction by an area labeled "b" which can be about 0.6 mm. Each element can be separated from the adjacent element in the MD direction by an area labeled "c" which can be about 1.2 mm. Density measurements of the various areas "a", "b", and "c" indicate that microSELFing of non-woven webs such as fibrous airlaid webs can result in low density out-of-plane deformation. In the embodiment depicted in FIG. 40, the base material has a density of about 0.088 g / cc, the area "a" has a density of about 0.0.072 g / cc, and the area "b" has a density of about 0.0.093 g. It had a density of / cc and the area "c" had a density of about 0.0.101 g / cc.

The density values mentioned above for Samples 2 and 10 shown in Figures 39 and 40 are approximate, and the density values are for the base material properties, the process used to generate the Z-direction deformation, and other materials and process variables. Understand that it can be changed accordingly. Generally, in the case of air-laid web in which at least a part of the fiber is cellulose fiber, the density difference between the density of the base web and the density of the Z-direction deformed portion is at least about 18% to about 50% for the present invention. It is considered beneficial. The density difference between the density of the base web and the density of the Z-direction deformation can exceed 20%, 30%, 40%, or 50%. The density difference is considered to be most beneficial when the density of the Z-direction deformation is less than the density of the base material. The density of the base material can be considered to be essentially the same as the density of areas "c" in FIGS. 39 and 40 in the web processed by the methods of the invention.

It is understood that the density values presented herein are for uncompressed webs that are processed to produce the absorbent cores described herein. The absorbent cores described herein may be used for disposable absorbent articles that are folded, compressed, packaged, and / or stored. Therefore, the density difference in the used state may be different from the density difference in the finished state. Therefore, the absorbent core material used in the packaged disposable absorbent article has the density of the Z-direction inter-deformation zone (eg, the zone represented by "b" and "c" in FIGS. 39 and 40). It is believed that the density difference between them can be exhibited and the density of the Z-direction deformed part can exceed 5%, 10%, 20%, 30%, or 40%. Air-laid non-woven absorbent cores containing cellulose fibers are currently most beneficial when the cause of the above density differences is due to the density of the Z-direction deformations, which is relatively lower than the density of the Z-direction deformation areas. It is being considered.

The density data described above for Samples 2 and 10 shown in Figures 39 and 40 is a Micro CT40 (Scanco Medical, Bassersdorf, Switzerland) X-ray scanner with high resolution, energy 35 keV, Obtained by use at 300 micrometer integration time and averaging 10. The tomographic reconstruction of the dataset used a field of view of 20 × 20 mm for X / Y and 2-3 mm for Z (depending on the sample) and an x / y / z resolution of 10 micrometers in all directions. Each dataset was approximately 2048 x 2048 in x / y and approximately 200-300 slices in the Z direction. After removing the sample holder from the field of view, the stack of remaining slices was analyzed as follows: 1) A threshold of 1000 was used to distinguish between the fibers and the background. 2) At each x / y point by finding the first fiber (any pixel over 1000) along the Z direction (perpendicular to the wiping surface) and the last fiber along the Z direction. The thickness was measured. The difference between these two Z-values indicates the thickness at each position of X / Y. I saved this image in TIFF format. 3) The basis weight image at each x / y point was measured by summing all the values over 1000 along the Z direction. I saved this image in TIFF format. 4) The density image at each x / y point was measured as the value of the basis weight image at (X, Y) divided by the value of the thickness image at (X, Y). An image with a thickness of 0 was set to 0 for a density image. I saved this image in TIFF format. 5) The user then selects an area within the thickness image. Classify each area as either thick or thin. The average thickness and standard deviation, average basis weight and standard deviation, and average density and standard deviation are then calculated for the selected area (in each image) and, if desired, eg, Excel®. Output report to .csv file in spreadsheet.

Test method 1. Preparation of artificial menstrual fluid For each test using artificial menstrual fluid (AMF), prepare as follows: Step 1: Dilute 1:10 mL of reagent grade 85-95% w / w lactic acid with distilled water to make 100 mL. Label it as 10% v / v lactic acid. Step 2: Add 11.76 g of reagent grade 85% w / w potassium hydroxide (KOH) to the flask and dilute with distilled water to make 100 mL. Mix until completely dissolved. Label 10% w / v KOH. Step 3: Add 8.5 g of sodium chloride and 1.38 g of hydrous sodium phosphate monobasic to the flask and dilute with distilled water to make 1000 mL. Mix until completely dissolved. Label as primary sodium phosphate solution. Step 4: Add 8.5 g of sodium chloride and 1.42 g of anhydrous sodium diphosphate to the flask and dilute with distilled water to make 1000 mL. Mix until completely dissolved. Label as dibasic sodium phosphate solution. Step 5: Add 450 mL of the second phosphate solution to the 1000 mL beaker and add the first sodium phosphate solution until the pH drops to 7.2 ± 0.1. Label as phosphoric acid solution. Step 6: Mix 460 mL of phosphate solution and 7.5 mL of 10% KOH in a 1000 mL beaker. The solution is heated to 45 ° C ± 5 ° C, then 28 sterile gastric mucilages (ICN Biomedical Inc., Cleveland, Ohio) are added. Continue heating for 2.5 hours to completely dissolve the gastric mucilage. Cool the solution below 40 ° C and then add 1.8 ± 0.2 mL of 10% v / v lactic acid solution. The mixture is sterilized under pressure at 121 ° C for 15 minutes and then cooled to room temperature. The mucous mixture should be used within 7 days. Label as gastric mucilage solution. Step 7: 500 mL of gastric mucilage solution and 500 mL of fresh sheep sterile derailed blood (Cleveland Scientific, American Biomedical, Bath, Ohio) in a beaker. Mix with. Label as Artificial Menstrual Fluid. Store refrigerated and use within 7 days.

2. Absorption capillary potential and desorption capillary potential Absorption capillary potential (also known as absorption energy) and desorption capillary potential (also known as desorption energy) can be measured by evaluating the capillary action potential for each test material.

The ability of an absorbent material to absorb or desorb a fluid by capillary potential is measured by capillary work potential. Step 1: Using a TRI Autoporosimeter from TRI (Princeton, NJ), the percentage of fluid saturation was determined by the pressure of the samples of Absorbent Cores I and II listed in Tables 1 and 2. Measure as a function. Step 2: The test fluid used here is n-hexadecane. Step 3: There are three test cycles that generate three capillary pressure vs.% saturation curves: 1) First absorption (swelling) using dry material 2) Drainage 3) Second absorption using infiltration material Step 4: The absorption capillary potential (absorption Capillary Work Potential (CWP)) is calculated by integrating the first absorption curve of the capillary potential as a function of the suction amount.<maths num="1"><img file="JP2010520005A_D0004.tif" /></maths> In the formula, CV is the measured cumulative uptake (convertible to saturation). Step 5: The desorption capillary work potential (CWP) is calculated by integrating the drainage curve of the capillary pressure as a function of the suction amount.<maths num="2"><img file="JP2010520005A_D0005.tif" /></maths> In the formula, CV is the measured cumulative uptake (convertible to saturation).

3. Transparency (of Darcy) and flow rate (g / sec) Transparency is measured from the mass flow rate of any given fluid through a porous medium. The procedure for measuring both is as follows: Step 1: Automatically distribute the flow of liquid through the sample by monitoring the distance of the column of water droplets in relation to time and pressure measurements using a through plane permeability device. And measure. Step 2: The pressure drop measures the mass flow rate of the fluid through the porous medium over the sample. Step 3 (for flow rates in Table 1): Variable pressure in falling hydro head mode using saline solution containing 2.75% calcium chloride as all fluids in the absorber I sample in Table 1. Measure the flow rate at. Step 3 (with respect to flow rate in Table 2): Measure the flow rate at a constant pressure using a constant head mode with distilled / deionized water for all fluids in the absorber II sample in Table 2. Step 4: Calculate Darcy permeability and flow rate by the following equation: F = k (A / μ) (Δp / l) --- (1) K = 9.87 × 10^-13k --- (2) In the formula: F = flow rate (g / sec) k = Porous material permeability (m)²) A = Cross-sectional area available for flow (m)²) l = Material thickness (m) μ = fluid viscosity (cP) Δp = pressure drop (cmH)₂O) K = Transparency (of Darcy)

4. Free eruption flow (%) This test measures the weight percent (% runoff) of fluid not acquired by the absorbent pad. This procedure involves placing 10 mL of artificial menstrual fluid (AMF) on an unloaded (new) sanitary napkin placed in the direction of the CD (ie, the width of the sanitary napkin in a flat state) with an inclination of 15 °. Includes loading on. The reported value is an average of N = 3.

Preparation of AMF: AMF is prepared at 23 ± 2 ° C (73 ± 4 ° F) for 2 hours before fluidization for testing.

Sample preparation and equipment: Step 1: Hold both ends of the pad and twist it 10 times, then bend the pad approximately 90 degrees and align the ends 10 times to prestress each pad to be tested. Step 2: Equilibrate the sample for at least 2 hours in a room adjusted to a temperature of 23 ± 2 ° C (73 ± 4 ° F) and a relative humidity of 50 ± 4% prior to the test. Step 3: Mark the center point of the narrowest width of the pad as the target fluid load point. The device includes a sample holder ring stand with a 15 ° fixed tilt base, a fluid delivery separatory funnel with nozzles, and a drainage basin.

procedure: Step 1: Weigh each sample pad to be tested. Step 2: Place the pad on the sample holder at a tilt angle of 15 ° in the CD direction and center the fluid delivery nozzle above the marked center point and 12.7 mm (0.5 inch) above the pad surface. To adjust. Step 3: Fill the separatory funnel with 10 mL of AMF. Step 4: Quickly open the funnel valve and allow 10 mL of fluid to drain completely from the funnel onto the pad surface within 3 seconds. Step 5: Weigh the wet pad. Step 6: The amount of fluid absorbed is measured by subtracting the dry weight from the wet weight of the pad. Subtract this number from 10 to determine the amount of unabsorbed fluid (runaway). This runoff is then divided by 10 and the result is multiplied by 100 and reported as a 10 mL free spout runoff.

5. HGW holding capacity HGW is an absorption test that measures fluid suction by an absorbent pad as a time function.

Preparation of AMF: AMF is prepared at 23 ± 2 ° C (73 ± 4 ° F) for 2 hours before fluidization for testing.

Sample preparation and equipment: Equilibrate the sample pads for at least 2 hours in a room adjusted to a temperature of 23 ± 2 ° C (73 ± 4 ° F) and a relative humidity of 50 ± 4% prior to the test.

procedure: Step 1: Place the sample pad horizontally upside down (top sheet side) in the holder basket suspended from the electronic scale. The desired encapsulation air pressure of either 0.41 kPa (0.06 psi) or 1.72 kPa (0.25 psi) is applied to the sample holder basket. Step 2: With respect to the pad, the tube of the fluid loading column connected to the fluid reservoir with zero hydrostatic head and filled with AMF is brought into contact with the top sheet of the pad as a point source, and the weight increase of the sample is used as fluid uptake over time. Step 3: Continue testing until the pad is completely saturated. Step 4: Stack and place 7 filter papers on a saturated pad, 1.72kPa (0.25psi (17.6g / cm))²)), Followed by 6.89kPa (1.0psi (70.3g / cm))²)) Load is applied to squeeze the fluid. Step 5: HGW retention capacity is the weight in grams of fluid remaining in the sample after squeezing. The reported value is an average of N = 3.

6. Rewetting pressure The rewetting pressure is the amount of pressure required to regurgitate the liquid from the wet lower absorbent core through the already wet topsheet.

Preparation of AMF: AMF is prepared at 23 ± 2 ° C (73 ± 4 ° F) for 2 hours before fluidization for testing.

Sample preparation and equipment: Step 1: Equilibrate the sample pad to be tested for at least 2 hours in a room adjusted to a temperature of 23 ± 2 ° C (73 ± 4 ° F) and a relative humidity of 50 ± 4% prior to the test. Step 2: The equipment used to measure the load force is a light load, such as the EME Model 607, Model 627, or Model 599A available from EME Co. (Newbury, Ohio). It is a tensile tester (Tensile Tester) with a grip for use. It features a sample holder base plate and compression sensor foot, also available from EME.

procedure: Step 1: Place the sample pad with the topsheet side facing up and place a Plexiglas fluid load exudation cap with a central hole in the center of the pad. Step 2: Distribute 7.5 ± 0.3 mL of AMF within 5 seconds through the central hole of the strike through cap. Step 3: Remove the strike through cap as soon as the pad has completely absorbed the fluid, then start a time of 5 minutes. Step 4: Place the loaded sample pad on the sample holder base plate and center the compression sensor foot just above the stain area. Step 5: At the end of 5 minutes, start the tensile tester. The crosshead should move down and compress the sample until fluid is detected. Step 6: The rewetting pressure is the compressive force divided by the area of the compression sensor foot. The reported value is an average of N = 3.

7. Acquisition speed (mL / sec) In this test, the ejection acquisition velocity, that is, the rate at which the absorbent pad acquires the fluid, is measured.

Preparation of AMF: AMF is prepared at 23 ± 2 ° C (73 ± 4 ° F) for 2 hours before fluidization for testing.

Sample preparation: Equilibrate test pad samples for at least 2 hours in a room adjusted to a temperature of 23 ± 2 ° C (73 ± 4 ° F) and a relative humidity of 50 ± 4% prior to the test.

procedure: Step 1: Place a 10.2 cm (4 inch) square block with a 2.5 cm x 1.5 cm (1 inch x 0.6 inch) opening (generally oval shape) above the center of the sample pad to be tested. To do. Add enough weight to the block to achieve a pressure of 1.72 kPa (0.25 psi) without blocking the opening. Step 2: Top of the opening over 2.25 hours at a rate of 2 mL / hour with a Low Flow Syringe Pump from Harvard Appliance (Southnatick, Mass.) Add AMF to the sample pad through. Step 3: Then, using an Eppendorf Maxipipetter from Fisher Scientific, add 3 mL of AMF to the sample pad at a time through the opening. The time interval between the first instillation of 3 mL of AMF and no AMF can be seen on the top surface of the sample. Step 4: Calculate the acquisition rate (mL / sec) by dividing the volume (3 mL) by the time (in seconds) measured in Step 3. The reported value is an average of N = 3.

The dimensions and values disclosed herein should not be understood as being strictly limited to the exact numbers listed. Rather, unless otherwise specified, each of these dimensions is intended to mean both the listed values and the functionally equivalent range around those values. For example, the dimensions disclosed as "40 mm" are intended to mean "about 40 mm".

All references cited in "Forms for Carrying Out the Invention" are incorporated herein by reference in the relevant parts, but any reference to any of the references acknowledges that it is prior art to the invention. It should not be interpreted as a thing. To the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of a term in the referenced literature, the meaning or definition given to that term in this document shall prevail.

Although specific embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various other modifications and modifications can be made without departing from the spirit and scope of the invention. Therefore, all such changes and modifications within the scope of the present invention shall be treated within the scope of the appended claims.