MXPA97010506A - Absorbent pillows perforated for use in absorbent articles - Google Patents

Abstract

The invention relates to absorbent pads, and to methods for manufacturing absorbent pads having improved fluid absorption and preferential transport in the longitudinal direction. The absorbent pads have patterns of openings that encourage preferential transport. The openings are characterized by the size, spacing from one another, and the depth of penetration into the absorbent pad, so that the rate of fluid intake is increased and the distribution of the fluid in the longitudinal direction is improved. The openings are preferably spaced sufficiently close together so that the aqueous liquid is preferably transferred from opening to opening by the capillary effect along the length of the absorbent pad. The preferential transmission between the openings in the longitudinal direction increases the absorption rate of the overall effective liquid of the absorbent pad, thereby increasing the capacity of the general liquid of the respective absorbent article. A novel method for manufacturing an absorbent pad of the invention includes penetrating within but not through the absorbent pad using the heated pin elements. The heated bolt elements form a plurality of perforations in a first surface of the pad, the pad has a higher density near the openings than the overall density of the absorbent pad. The lower density areas of the pad have higher water absorption rates than the higher density parts of the pad absorb

Description

ABSORBENT PILLOWS PERFORATED FOR USE IN ABSORBING ITEMS FIELD OF THE INVENTION The present invention relates to perforated pads for use in absorbent articles. More particularly the invention relates to patterns of perforations, sizes of the openings, depths of the openings, and other aspects of the perforated absorbent pads that improve the rate of absorption to receive the aqueous fluid within them, the movement of the liquid within the absorbent pad, and the effective ability of the pad to receive the liquid and move the liquid along the length of the absorbent pad.

BACKGROUND OF THE INVENTION Absorbent pads are well known for use in absorbent articles. The absorbent pads can be located, for example, between the body-side liner and the outer cover of an absorbent article.

Absorbent pads receive and retain fluid from a user's body. The absorbent pad can be effective to receive from the wearer's body, and to retain a sufficient amount of the liquid to prevent the liquid from dripping from the absorbent article.

It is known to use perforations in the absorbent articles to help channel liquids out of the wearer's body and into the absorbent material of the absorbent article. In such conventional use, a liner sheet of the absorbent pad is attached to an absorbent body of the absorbent pad. In such conventional embodiments, the perforations extend through the absorbent body, and the liner sheet extends to the opening which is attached to the backing sheet or to a binding sheet on the opposite side of the absorbent pad.

A padded diaper having perforations extending through the absorbent pad is also known. An inner sheet is secured to a backing sheet to the perforations. An intervening layer having smaller perforations can be located between the inner sheet and the absorbent pad.

It is also known to have a disposable insert for a diaper wherein the insert has a top sheet, waterproof but with slits. The slits extend completely through the upper sheet, and can be opened and allow the passage of liquid therethrough, to enter an underlying absorbent pad until the pad is saturated. Upon receipt of the liquid inside the absorbent pad. The dimples in the absorbent pad expand, and close the slits allowing essentially no liquid to enter or exit the absorbent pad after the absorbent pad is saturated with the liquid.

SYNTHESIS OF THE DESCRIPTION This invention relates to absorbent pads, especially to absorbent pads used to absorb body exudates, and to methods for making such absorbent pads, having improved fluid absorbency rates and a preferred transport along the longitudinal dimension of the pad. The absorbent pads have perforation patterns which encourage the preferred transmission. The openings are characterized by the size, separation of each other and the depth of penetration to the absorbent pad as well as an increased density of the fibrous material of the pad around and near the surfaces of the openings, so that the rate of fluid absorption is increased and fluid distribution in the length direction is improved, over the rates and distribution of conventional pads.

The pads are preferably sufficiently spaced apart from each other so that the aqueous liquid is transferred from opening to opening by a capillary effect. The separation and arrangement of the openings in the arrangement of openings is such as to facilitate the crossing of the liquid, which is being absorbed within the pad and transferred into the pad, along the length of the absorbent pad, rather than across the width of the pad. The preferred transmission between the openings in the longitudinal direction increases the absorption rate of the effective liquid in general from the absorbent pad, because the absorbed liquid is rapidly transported out of the absorption site, thereby emptying the space in the place of absorption. absorption, whose empty space can be used to quickly absorb additional amounts of liquid. The perceived value of the invention is thus to increase the overall effective capacity of the absorbent article to absorb the liquid over a relatively short period of time representative of the conditions of use in absorbing body exudates.

A novel method for manufacturing an absorbent pad of the invention includes penetrating into but generally not through the absorbent pad, using hot pin elements. The hot bolt elements form a plurality of perforations in a first surface of the pad. The pad has a higher density near the openings than the overall density of the absorbent pad. The lower density areas of the pad have higher water absorption rates than the higher density portions of the absorbent pad.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a top view of a first embodiment of an absorbent pad of the invention.

Figure 2 shows a cross section of the absorbent pad taken at point 2-2 of Figure 1.

Figure 3 shows a fragmentary cross-section of the apparatus for forming the perforations in the absorbent pad according to the invention.

Figure 4 shows a pictorial view of a first flat nose tip of a bolt element for use in the apparatus of Figure 3.

Figure 5 shows a graphical view of a second bolt element having a cavity axially inwardly at the tip of the bolt element.

Figure 6 shows a top view representatively of an absorbent article including an absorbent pad of the invention.

Figure 7 shows a cross-section of the absorbent article, taken at point 7-7 of Figure 6.

Figure 8 shows a top view of an absorbent pad that also does not work as desired.

Figure 9 shows a top view of another absorbent pad of the invention.

Figure 10 is a graph showing the comparative transport distance as a function of the aperture size and arrangement.

Figure 11 is a graph showing a comparative absorption time as a function of the size and arrangement of the opening.

The invention is not limited in its application to the details of the construction and arrangement of the components set forth in the following illustration or illustrated in the drawings. The invention is capable of other incorporations or of being practiced or carried out in several ways. It is also understood that the terminology and phraseology used herein is for the purpose of description and illustration and should not be viewed as limiting. The reference numbers are used to indicate similar components. In addition, the drawings mentioned above are not taken to scale and should not limit the invention.

DESCRIPTION DETAIL OF ILLUSTRATED INCORPORATIONS The present invention is directed to an absorbent article having an increased fluid absorption rate and an improved fluid distribution. The invention includes an absorbent pad having a number of perforations arranged in a pattern to promote transport in the longitudinal direction. The number of openings, the area of the openings, and the depths of the openings, all * s contribute in combination, to the effect of improved transmission or transport, and to the distribution of the liquid. Another benefit of the invention is that the openings improve the structural integrity of the absorbent pad.

Through the description and claims, the phrase "absorbent article" means products for the care of the infant, for the care of the adult and for the care of the woman which absorb the fluid from the body of the user.

Through the description and claims, the word "fluid" means flowable elements of urine, fluid contng feces, menstrual fluids and any other body fluid that can be transferred from a user to an absorbent article.

The terms "densification" and / or "densified" define parts of an absorbent pad which have a higher density of the fibrous material, such as cellulose wipes, than the average general density of the respective absorbent pad. Such densification, however, leaves a sufficient open space in the fiber matrix to easily receive aqueous liquids there by absorbing liquids inside the pad 10.

Figures 1 and 2 illustrate a first absorbent pad 10 of the invention. The absorbent pad 10 includes a first perforated surface 12, and a second opposing reference surface 14. The absorbent pad 10 has a length of "L", a width "W", shown in Figure 1, and a thickness "T" , shown in Figure 2. The second reference surface 14 preferably has no perforations, or has few perforations. The absorbent pad 10 has a longitudinal axis 16 that extends along the length thereof. A multitude of openings 20 extend from the first surface 12 inwardly to the absorbent pad to the second reference surface 14, and generally end as blind holes in the respective bottoms 24. The perforations 20 are typically formed at a point of attachment by heated bolt elements.

The absorbent pad material around the openings 20 is denser than the portions of the absorbent pad 10 which are separated from the openings. Such denser zones around the openings 20 encourage the transport of fluid to the denser areas. Preferred embodiments have aperture patterns which preferably convey the fluid longitudinally along the length of the absorbent pad 10 outwardly from the center thereof. Thus, the openings 20 improve the overall distribution of the fluid and the absorbent pad 10. Surprisingly, the number of openings, the separation of the openings, and the arrangement of the openings in the aperture arrangement can also improve the absorption rate of the apertures. the absorbent pad 10. Thus, the absorption rate and the distribution pattern of the liquid within the absorbent pad 10 are improved in the invention.

The example perforations 20 shown in Figure 1 are rectangular. Such rectangular perforations can have a length of up to about an inch and a width of up to about a quarter of an inch. As illustrated in Figure 1, some or all of the openings may have smaller sizes. Indeed, in some embodiments of the invention, all openings have essentially the same size, both in cross-sectional dimensions and depths. However, the cross sections of the opening and the depths of the openings may differ from different openings in the same absorbent pad.

As shown in Figure 1, the elements of the rectangular openings 20 extend along the "L" length of the absorbent pad 10.

In the preferred embodiments, essentially none of the openings 20 extends through the absorbent pad 10 and thus penetrates the surface 14. As shown in Figure 2, the openings 20 generally extend from the first surface 12 inwards. of the absorbent pad for about 90 percent of the "T" thickness dimension of the absorbent pad 10. As shown in Figure 2, each opening 20 has an interior opening surface 22 extending from the first surface 12 toward the bottom 24, and including the side walls of the perimeter 25 over the interior of the opening. During manufacture or during subsequent handling, some or all of the bottoms 24 may be broken as shown in point 27 in Figure 2, so that the respective openings extend in principle completely through the absorbent pad 10. Generally, however, the bottoms 24 are closed as shown in the openings illustrated on the left side of Figure 2. However, even where the bottom is broken as in point 27, the open area of the opening thus created is small. in comparison with the open cross-sectional area (top view) of the main body of the respective opening 20. "In either case, the breaks 27 represent the bottoms 24 in which the openings have been created, and where the bottoms 24 generally They remain intact but broken.

The absorbent pad 10 suitably comprises a matrix of hydrophilic fibers, such as a cellulose fluff cloth. Optionally, a high-absorbency material, commonly known as superabsorbent material may be included in the absorbent pad 10. In a particular embodiment, the absorbent pad 10 may include a mixture of hydrogel-forming, supersorbent and wood pulp particles. . Even when cellulosic fluff is preferred one can use synthetic fibers, polymeric fibers, meltblown fibers or a combination of meltblown fibers and natural fibers. The superabsorbent material may be mixed essentially homogeneously with the hydrophilic fibers, or may otherwise be combined in an absorbent pad 10.

The absorbent pad 10 may comprise a laminate of fibrous fabrics and a superabsorbent material or other suitable means for maintaining a superabsorbent material in a localized area.

The absorbent pad 10 can have any of a number of shapes. For example, and if in limitation, the absorbent pad 10 may be rectangular in I-shape or T-shaped.

The high-absorbency material in the absorbent pad 10 can be selected from polymers and natural, synthetic and modified natural materials. High-absorbency materials may be inorganic materials, such as silica gels, or organic compounds such as degraded polymers. The term "degraded" refers to any means to be effectively materials normally soluble in water, essentially insoluble but spongy in water, so that the absorbent properties are available but the sponge is essentially immobile after the absorption of the liquids based on Water. Such means may include, for example, physical entanglement, crystalline domains, covalent bonds, ionic complexes and associations, hydrophilic associations, such as hydrogen bonding, and hydrophobic associations or Van der Waals forces.

The absorbent pad 10 may include a standard barrier tissue layer 29 covering the first surface 12 and a layer of forming tissue 31 that covers the second reference surface 14 of the absorbent pad. Such tissue layers are well known in the art both in terms of materials and functions. The tissue layers are generally fluid permeable but retain the material of the absorbent pad 10 there. In adult care products, however, a single tissue layer may be wrapped completely around and secured to the absorbent pad 10. Other arrangements containing layers of various materials placed on surfaces 12 and 14 and / or encompassing the absorbent pad 10, are contemplated as being within the scope of the invention.

As shown in FIG. 2, the inner opening surface 22 of an opening 20 comprises all of the surfaces of the pad placed within the opening 33 of said bore. Thus, the interior opening surface 22 includes the respective bottom 24 as well as the side walls 25. The density of the absorbent pad near the inner piercing surface 22 is greater than the overall average density of the absorbent pad. Such a higher density therefore generally extends along the full depth of the sidewalls 25 as well as through the bottom 24. Such increase in density is generally accompanied by the corresponding increase in the overall structural integrity of the absorbent pad 10, whereby the structural integrity of the absorbent pad 10 is more easily maintained during the use of the absorbent pad.

In operation, when a discharge of liquid such as urine is poured into the center of the first surface 12 of the absorbent pad 10, "the perforations or openings 20 help to distribute the urine along the length" L "of the absorbent pad which extends along the longitudinal axis 16. First, the free-flowing liquid is received within the hollow volume Secondly, the denser areas surrounding the openings, including the sidewalls 25 and the bottoms 24 convey the liquid more efficiently than the areas of average density.Thirdly, the areas of intermediate density between the openings arranged along the length "L" also press the movement of liquid in a longitudinal direction along the length L. and outward from the place of discharge 4. Fourth, the areas of lowest density, separated more distant from denser areas than areas of intermediate density, absorb the liquid at an absorption rate higher than those of higher density areas. The urine or other exudates in both longitudinal directions of the front and back along the longitudinal axis 16 are improved by the openings 20 as in Figure 1.

The absorbent pad 10 of Figure 1 has an exemplary length of about 21 inches, an example width of about 5.5 inches, and an example thickness "T" of about one quarter of an inch.

This pad size is preferred in adult care products. Other absorbent pads 10, having the smaller sizes, are generally preferred for infant care and for feminine care products and are also within the scope of the invention, as are the larger size absorbent pads.

In preferred embodiments, the invention contemplates at least 40 of the openings 20 to provide the proper transport effect without leaving an adverse consequence on the fluid discharge. Most incorporations preferably have at least 80 openings. The large number of openings provides more places of increased density located on the first surface 12 of the absorbent pad 10. The large number of places improves the distribution, for example, the transmission of the fluid through the opening to the opening. In some embodiments or incorporations, they include 120 or more openings. However, the number of openings becomes very large, the size of the corresponding opening can be so small that the beneficial effects of the invention are not achieved.

The individual openings 20 each have a cross-sectional area through the cross-sectional area between the side walls 25 of the respective opening. Such an area in transverse cross section is defined as an imaginary axis extending through the absorbent pad 10, for example, perpendicular to the surface 12. The open cross-sectional area is typically from about 0.0025 square inches to about 0.25 square inches. For perforations having a smaller cross-sectional area, the impact on fluid distribution and absorption is not significant.

The ratio between the cross-sectional area of the openings 20 and the total surface area of the first surface 12 is also an important feature of the invention. The sum of the open cross-sectional areas of the openings 20 should be in a range of from about 5 percent to about 40 percent of the total surface area of the first surface 12 of an absorbent pad 10. For best results, the The open cross-sectional area more preferably comprises from about 11 percent to about 32 percent of the total surface area of the first surface 12.

In FIGURE 1, the ratio of the length of the individual openings 20 to the "L" length of the absorbent pad 10 along the longitudinal axis 16 is about 1:20. The invention contemplates the proportion of the length of the individual openings 20 with respect to the length "L" being from about 1:10 to about 1: 250 The length of a circular opening 20 can be reduced by using the diameter of the opening.

Even though FIGURE 2 shows the openings 20 having the depths equal to about 90 percent of the "T" thickness, depths of from about 40 percent to about 99 percent of the thickness are permissible with preferred depths being at least 50 percent, more preferably at least 60 percent. In addition, some openings 20 can penetrate through the bottom 24 of the absorbent pad 10 without destroying the utility of the pad. Such penetration generally comprises a bottom opening 24, such as break 27, which is smaller, typically and essentially smaller in cross section than the cross section of the general open area defined by the respective opening 20.

FIGURE 1 shows a multiple serpentine pattern for the rectangular perforations 20 in the first surface 12 of the absorbent pad 10. As will be shown by the examples, thereafter, the arrangement of openings 20 with respect to each other has a profound effect on the distribution of the fluid in the longitudinal direction of the absorbent pad 10. Furthermore, and surprisingly, the arrangement of the openings with respect to each other can now increase the fluid intake rate of the absorbent pad over a reasonably short test period.

The general nature of the apparatus useful for forming the openings 20 in the absorbent pad 10, or a continuous absorbent core passing through a pressure point, is described in U.S. Patent No. 4,886,632 issued to Van Iten. and others which is hereby incorporated by reference in its entirety. Van Iten et al. Describe an apparatus for forming openings of a generally uniform open cross section through the entire thickness of a fabric. The invention herein utilizes the apparatus of Van Iten et al., With modifications to the apparatus and methods of use as described hereinafter to form the bottom openings generally in the absorbent pads 10 having many thicknesses greater than the fabrics of Van Iten. and others. U.S. Patent No. 5,188,625 issued to Van Iten et al., Incorporated herein by reference in its entirety discloses using a similar apparatus to form the perforations through the liquid permeable cover layer.

FIGURE 3 shows a cross-sectional view of the absorbent pad 10 directed through a pressure point defined by a first member including a bolt element 26 and a second member including a strip 28 and the sleeve 30. The bolt element 26 It has a rounded tip 32 as shown. The rounded tip 32 tends to form a rounded bottom 24 for the opening thus formed, without fully penetrating the thickness "T" of the absorbent pad 10. The heating units (not shown) heat the respective bolt elements 26 and the sleeve 30 The strip 28 and the sleeve 30 comprise the heat conducting material, such as bronze, steel or aluminum. The bolt elements 26 also comprise a heat conducting material, such as bronze or steel.

In operation as the pad 10 moves through the pressure point, the respective heated bolt elements 26 of the first member enter the heated strip 28, penetrating 2 Q .; the openings 34. The force of the bolt elements 26 rotating through the pressure point urges the respective elements of the absorbent pad 10 to the openings 34 of the strip 28, thereby forming the openings 20 in the absorbent pad. The heating of the bolt elements 26 and the strip 28 including the outer walls of the openings 34 in combination with the force exerted at the pressure point, the absorbent pad 10 softens the fibers while the respective collection of fibers is being worked by the bolt element 26. The fibers are therefore compressed together while in the heated condition, both at the tip 32 and along the side walls 34, squeezing the pad between. the bolt element 26 and the side walls 25, and between the bolt element 26 and the second surface 14.

While fibers 12 and 13 of the Van Iten and others' 632 patent show a shoulder on the bolt element forming an enlarged area of a higher density material on the surface of the sheet being processed, the enlarged area may Reducing by tapering the bolt element shoulder as shown in FIGURE 3, the Van Iten bolt element and others breaks the sheet of material being worked. In contrast to figure 3 of the applicant's application, the bolt element breaks a few fibers if it breaks any and forcibly forces a part of the thicker absorbent pad of the applicant 10 into the opening 34 where the densification is carried out. .

Preferred temperatures of strip 28 and bolt elements 26 are equal to greater than 200 degrees F to about 400 degrees F. Temperature and pressure, in combination at the pressure point, cause densification of absorbent pad 10 by and around the openings 20 thus formed by the combination of softening and simultaneously comprising the material of the absorbent pad. Warming tends to soften, melting and / or joining the fibers of the absorbent pad 10 in the compressed dense state shown in Figure 3. Thus, after the materials of the absorbent pad 10 have passed through the apparatus 35 of Figure 3, the combination of compression and heating so that the pad material on one side of the openings 20 permanently retains its compressed characteristics and correspondingly the high density, close to the entire opening surface 22, including the side walls and the bottoms of the respective openings. In contrast, the sharp tip of the Vain Iten bolt element penetrates completely through the thinner cloth material, so that the openings serve more as drainage conduits than as reservoirs for containment as in the present invention.

The bolt elements 26 and the strip 28 can be cooperatively configured to provide open but still blind openings as shown in FIGURE 1. By "blind" it is meant that the opening is open at only one end, for example, the end on the surface 12.

Other configurations and arrangements of the bolt elements 26 and the cooperative openings 34 are within the scope of the invention. For example, Figure 4 shows a bolt element 26 having a flat end at the tip 36. The tip 36 is preferably reasonably chamfered, whereby the tip 36 generally creates the openings 20 without full penetration of the absorbent pad 10.

FIGURE 5 shows a bolt member 26 having a recessed end 38 at the tip, including an eyebrow 37, and a cavity 39 extending, from the eyebrow 37, axially and transversely inwardly of the end. In use with the openings 35 of Figure 3 the tip having the recessed end forms a cushion of a partially densified material at the bottoms of the respective openings. The density of the cushion thus produced is greater than the overall density of the absorbent pad 10 and less than the greater density of the pad material at the eyebrow 37. Other shapes, such as star shapes, diamond shapes, and shapes of triangle or other ornamental and / or utility designs can be used for the bolt elements 26.

The diameter of the bolt element, the shape of the bolt element, the temperature of the bolt / strip element, the pattern of the bolt element, the separation of the pressure point and the pressure at the attachment point are among the variables that can be controlled by forming the absorbent pad 10. These variables can change the density and pattern of the openings 20 and therefore the overall operation of the absorbent pad 10. For example, in some embodiments the bolt elements 26 do not need to be heated .

Referring to FIGURE 3, the opening / open space between the side wall of the bolt element 26 and the side wall 34 of the opening is sized in comparison with the thickness and strength of the pad / fabric on which it is to be worked, and the bolt element 26 is configured to be sufficiently blunt so that complete penetration from surface to surface is prevented so that the bolt member 26 pushes on the cushion material on the surface 12, pushing the cushion material forward of this, up to the opening in the strip 28, with the corresponding compression and densification of the pad material to thereby be a closed and blind end opening in the pad material with the open end of the opening opening in the surface 12. FIGURE 3 illustrates only one such bolt element forming only one opening. Many bolt and strip opening elements can of course be used on the cooperating coincidence pressure point rollers to form such a perforated product at production line speeds. The bolt element 26 may be pointed, but sufficiently separated from the sleeve 30, to prevent complete penetration of the fabric / pad being worked.

FIGURES 6 and 7 illustrate the absorbent pad 10 incorporated within an absorbent article 40. The absorbent article 40 includes the absorbent pad 10, the side-to-body liner 42, the outer cover 44, and the fastening lugs 46. The lining side to body 42 is generally in a surface to surface relationship with the first surface 12 of the absorbent pad 10. The outer cover 44 is generally in a surface to surface relationship with the second surface 14 of the absorbent pad 10. respective elements shown in Figure 7 can be secured to one another by ultrasonic bonding, adhesives, other methods well known in the art.

FIGURE 6 shows a serpentine pattern of openings extending along the length of the pad 10.

These are shown four rows of openings 20, each extending along a serpentine path. The opening pattern 20 shown in FIGURE 6 thus appears four alternating fine waves. The adjacent paths of the openings 20 alternate between the repetitive maximum distances "MXW" and the minimum repetitive distances "MW" between the successive openings in the respective adjacent paths.

The absorbent article 40 in FIGURE 6 is applied to the body of a wearer by securing the tie members 46 at a rear portion of the absorbent article to a securing surface element (not shown) on the outer cover 44 of the front part . The fastening lugs 46 may, for example, comprise the hooks of a hook and loop fastening system. The securing surface element typically comprises a corresponding curl material attached to the outer cover 44 on the front of the absorbent article 40 and adapted to engage liberally with the hook material. Other well-known fastening devices can also be used to hold the absorbent article 40 on the user. For example, a cohesion system, an adhesive fastener system, belts, or the like, can be used to secure the absorbent article 40 to the wearer's body.

A suitable body spun liner 42 can be manufactured from a wide selection of fabric materials, such as porous foams, rectified foams, perforated plastic films or natural fibers. For example, the body side liner 42 may comprise wood or cotton fibers. Other possible materials are synthetic fibers, such as polyester or polypropylene fibers, or a combination of natural and synthetic fibers. The body side liner 42 is suitably used to help isolate the liquids retained in the absorbent pad 10 from a user's skin.

Various woven and non-woven fabrics can be used for the body-side liner 42. For example, the body-side liner 42 can be composed of a meltblown fabric or bonded with polyolefin fiber yarn. The body side liner 42 may also comprise a carded and / or bonded fabric composed of natural and / or synthetic fibers. The body side liner 42 may also be composed of an essentially hydrophobic material wherein the hydrophobic material is treated with a surfactant or otherwise processed to impart a desired level of wettability and hydrophilicity.

In a particular embodiment of the present invention, the body side liner 42 may comprise a non-woven fabric, bonded by polypropylene yarns composed of denier fibers of about 2.8-3.2 formed into a fabric having a basis weight of about of 22 grams per square meter and a density of about 0.06 grams per cubic centimeter. The fabric is then treated on the surface with about 0.3 percent by weight of a surfactant. The body side liner 42 may comprise a triplicate of components or layers which correspond to any of the materials described herein, as well as to other materials known in the art.

Since the cloth material from which the body-side liner 42 is made has a general pattern of generally uniform pores, the liner itself is preferably free of openings or slits of larger size formed after the material has been manufactured. lining side to body. The perforations having a diameter of more than about 0.1 inches or slits having a length of more than about 0.25 inches, in the side-to-body liner are not contemplated as being desirable for the described invention. In addition, the body side liner 42 more preferably comprises a fabric of a material, permeable to liquid, and having no openings or slits of a significant size or length formed therein.

It is generally preferred that the outer cover 44 of the absorbent article 40 be formed of a material which is essentially impermeable to liquids. A typical outer cover can be made of a thin plastic film or other material impervious to the flexible liquid. For example, the outer cover 44 can be formed of a polyethylene film having a thickness of from about 0.012 millimeters about 0.51 millimeters. If the outer cover 44 is to have a more textile fabric type feel, it may comprise a laminated polybutylene film or a surface of a nonwoven fabric, such as a fabric bonded by spinning polyolefin fibers. For example, a polyethylene fabric having a thickness of about 0.015 millimeters may have thermally laminated thereto or otherwise a cloth bonded by spinning polyolefin fibers having a thickness of from 1.5 to 2.5 denier per filament, the fabric of which is not woven has a basis weight of around 24 grams per square meter. In addition, the outer cover 44 can be formed of a woven or non-woven fibrous web which has been fully or partially constructed or treated to impart a desired level of liquid impermeability to selected regions that are on or near the pad Absorbent 10. Further, outer cover 44 may optionally be comprised of a microporous material which allows vapors to escape from absorbent pad 10 and through outer cover 44 while preventing liquid exudates from passing through. the outer cover 44.

An optional discharge layer (not shown) may be located between and in surface-to-surface contact with the first surface 12 of the absorbent pad 10 and / or the side-to-body liner 42. The discharge layer may comprise the established materials in U.S. Patent No. 5,486,166 issued to C. Ellis and D. Bishop entitled "Fibrous Non-Woven Fabric Discharge Layer for Absorbent Personal Care and Similar Products" and the United States Patent No. 5,490,846 issued to C. Ellis and R. Everett, entitled "Improved Fiber Free Discharge Handling Fabric for Absorbent Personal Care and Similar Items", the descriptions of which are incorporated herein by reference.

In addition, other discharge layer materials known in the art may also be used.

Upon construction of the absorbent article 40, the absorbent pad 10 is placed between the outer cover 44 and the side-to-body liner 42. The side-to-body liner 42 and the outer cover 44-are then secured one to the other with the pad absorbent between them. Optionally, the absorbent pad 10 can be secured to the outer cover 44 and / or the side-to-body liner 42. The securing can be effected by adhesives, ultrasonic bonding, sewing or other well known methods to form an absorbent article. The body side liner 42 does not extend essentially into the openings 20 of the absorbent pad 10, and specifically does not generally follow the side wall 25. Rather, the side-to-body liner 42 is separate from the bottom 24 and is generally the side wall 25.

When the absorbent article 40 is mounted on a wearer's body, fluid such as urine contacting the absorbent pad 10 preferably flows along the longitudinal direction of the pad and is absorbent within the pierced pad. The serpentine pattern and the relative spacing of the openings 20 from each other, as in Figure 6, helps pull the fluid in the longitudinal direction along the first surface 12 and from within the absorbent pad 10 and the openings 20.

A knob of how an absorbent article 40 operates and includes a first of the openings 20 initially receiving the liquid. After a substantial passage of the liquid through the liner from side to body 42 and up to the first opening 20, the liquid is pulled by the capillary effect to a second opening 20, closely adjacent to the first opening. The openings of the serpentine pattern are located sufficiently close to one another to generally promote the transport of the fluid in the longitudinal direction, by preferentially passing the liquid from an opening to the second opening by a capillary effect. Therefore, by using the capillary effect as well as other transport properties, the fluid can be pulled from the first opening to the second opening. The effect can be repeated for other openings separated relatively closely along a given path (serpentine) to promote a flow in the longitudinal direction. The pattern of the openings 20 thus provides a path for improved transport and distribution of the fluid in the longitudinal direction.

As shown in Figure 6, the openings in a given serpentine path can be spaced apart from one another by a distance approximately equal to the diameter of a single opening. By separating the openings using the bolt elements 26 for example, in the formation of the openings, the pad material bridging between such closely adjacent openings is partially densified / compressed, thus to encourage the fluid to flow along of the path of the openings in the direction of the longitudinal axis 16, along the length of the absorbent pad 10, in preference to the flow transverse to the axis 16.

Another theory regarding the effect of the absorbent pad 10 of the absorbent article 40 can be expressed by considering the density at the locations of the absorbent pad. The densified openings 20 of the absorbent pad 10 have a greater density at the locations on the first surface 12 of the absorbent pad spaced out from the openings. As described above, the differences in density are caused by the apparatus 35 of Figure 3 which uses heated bolt elements 26 to form the openings 20.

In addition, in theory, the first surface areas of the pad 10 to a first distance "D" of the openings 20 have a higher density than the areas of the absorbent pad at the locations with the first surface of a distance greater than "D". "out of the openings. This is believed to be caused, at least in part, by the compression of the absorbent pad 10 on the first surface 12 caused by the physical formation of the openings 20. Therefore, in addition to forming the openings 20 having a higher density material , the apparatus 35 shown in Figure 3 pulls the material of the pad 10 towards several openings, thereby increasing the density of the absorbent pad 10 on the first surface 12 to a distance "D" around each opening. Therefore, the transport effect of the fluid is increased within the area of the absorbent pad 10 which is within the first distance "D" of the respective opening 20. In practical terms, the pattern of the openings 20 is preferably arranged from so that at least one second opening 20 is inside the first distance "D" from each opening. Typically the second and third openings are generally arranged on the surface 12 on the opposite sides of each opening, thus to define a given of the paths / lines of serpentine or other openings, and therefore a distribution line for transporting the liquid preferably longitudinally from the place of application of the discharge. This arrangement increases and promotes the transmission of fluid from opening to opening. The openings 20 are generally aligned and spaced apart in the longitudinal direction to promote distribution of the fluid in the longitudinal direction, thereby obtaining the use of a larger portion of the first surface 12 of the absorbent pad 10 to receive and retain sudden discharges of quantities. relatively large (amounts of body exudate) fluid.

Even though the first distance "D" has not been specifically calculated, the invention contemplates that the density gradient of absorbent pad material 10 decreases with increasing distance from one of the openings 20. Therefore, the first distance actually describes the distance at which the density of the absorbent pad 10 on the first surface 12 decreases sufficiently to prevent the preferred passage or spreading of the fluid to the next of the openings 20 by a capillary effect or the like. The density of the material on and to one side of the first surface 12 of the absorbent pad 10 may continue to decrease as a gradient beyond the first distance from one of the openings 20. The first distance "D" may comprise at least the diameter of an individual openings 20, and can comprise a greater distance. At least one and preferably two openings 20 aligned in the longitudinal direction are arranged within the first distance of one of the apertures so that the fluid is directed from the first of the apertures along and near the first surface of the pad absorbent 10 to the other nearby openings.

Even when the aforementioned theories of operation attempt to explain how improved absorbency and fluid distribution are obtained, applicants choose not to be bound by any particular theory described above. The test results described below illustrate the surprising advantage gained by the invention.

PROOF PROCEDURE The tests were carried out using a Fluid Absorbency Return Fluid (FIFE) evaluation tester (not shown). The FIFE tester has two PLEXIGLASS plates.

The upper plate of the FIFE tester includes a cylinder having an inside diameter of two inches. The upper plate has a circular hole formed in the center thereof. The cylinder extends upward essentially perpendicular to the surface of the upper plate. The cylinder fits inside the circular hole and is therefore secured there by means of an adhesive. The adhesive permanently secures the cylinder from an integral part of the top plate and prevents the liquid from flowing out onto the top surface of the top plate. The bolt elements are positioned almost outside the corners of the bottom plate. The bolt elements align with the openings in the top plate to mount the plates together. A funnel is placed on top of the cylinder to pour the liquid into the test device. The combined mass of the FIFE top plate including the cylinder and the funnel is from 900 to 1100 grams.

The test products comprised the absorbent pads of DEPEND undergarments of Extra Absorbency and Elasticity on the Leg. The absorbent pads had a length of 21 inches, a width of 5.5 inches and a thickness of about 0.25 inches. For the purposes of the test, the elastics were removed.

In use, an absorbent article 40 DEPEND including a body side liner 42, an outer cover 44, and an absorbent pad, were placed with the body side liner 42 in a surface-to-surface relationship with the top plate of the body. FIFE tester. The outer cover 44 of the absorbent article 40 was in a surface-to-surface relationship with the bottom plate of the FIFE tester. Therefore, the absorbent article 40 was located between the upper plate and the bottom plate. In use, the lower plate and the upper plate of the FIFE tester both define the essentially horizontal planes.

The absorbent pad 10 was centered so that the cylinder of the upper plate of the FIFE tester was above the center of the absorbent pad and in contact with the liner from side to body. The test began with a first insult of 80 milliliters of salt water solution that was rapidly poured into the test cylinder through a funnel placed on top of the cylinder. The time from the first contact of the solution with the absorbent article was recorded until a complete absorption occurred (absorption time in seconds) immediately after the liquid was completely absorbed, the length of the pad over which the liquid was distributed , was measured, thus giving a transport distance. The liquid was colored to facilitate the detection of the transport distance. This measurement was taken from the edges of the colored material on the extreme left point to the extreme right point of the liquid stain along the longitudinal axis 48 of the absorbent article 40. After a five minute wait a second discharge of the liquid was poured. 80 milliliters inside the FIFE cylinder. Time and distance were recorded for the first download. A stubborn and final discharge of 80 milliliters was applied with another five minutes of delay, and absorbency and transport values were recorded. A final five-minute delay was added to compare the effects of the transmission over time. Only the measurements of the transmission distance were taken after the last five-minute delay.

TEST RESULTS FIGURES 8 and 9 show the patterns of openings used to generate the test results. FIGURE 8 shows a solid pattern (A) of openings 20 having diameters of 0.109 inches. FIGURE 9 shows a solid pattern (B) of the openings 20 having diameters of 0.25 inches. FIGURE 6 shows an absorbent article 40 including the absorbent pad 10 having a serpentine pattern (C) of the openings 20 which gained the test results overall improvements. The absorbent pad was tested having no openings to use as a control for the other experiments. The results are listed as follows. The measured transport distance is in inches in the longitudinal direction between the leading edges of the colored material on the opposite sides of the colored material resulting from the discharge, measured along the longitudinal axis 48 of the absorbent article. The transport distance is measured at the moment when the cylinder fluid has been completely absorbed by the absorbent pad. The last measurement is taken five minutes after the third fluid discharge has been absorbed by the absorbent pad. TABLE 1: TRANSPORT DISTANCE SUMMARY FIRST SECOND THIRD AFTER PATTERN DOWNLOAD DOWNLOAD DOWNLOAD 5 MINUTES Control 6.0 in. 7.7 in. 9.9 in. 12.4 in.

Control A 7.3 in. 10.2 in. 13.4 in. 16.1 in.

Control B 6.2 in. 9.0 in. 12.7 in. 15.9 in.

Control C 6.2 in. 9.8 in. 13.3 in. 16.8 in.

As shown in the aforementioned data, all the parameters of the upper density openings 20 had an increased transmission in the length direction over those of the control, which had no openings. The absorption time for each discharge is equal to the time required for the entire amount of fluid in the test cylinder to be absorbed by the absorbent pad. The absorbency time differed greatly for the parameters tested as follows: TABLE 2: ABSORPTION TIME SUMMARY PATTERN FIRST DOWNLOAD SECOND DOWNLOAD THIRD DUMP Control 27.8 sec. 57.5 sec 57.3 sec Control A 40.1 sec. 61.1 sec. 80.1 sec. Control B 14.2 sec. 32.2 sec. 33.4 sec. Control C 11.0 sec. 31.0 sec. 31.4 sec.

The pattern A included is a complete perforated pattern as shown in Figure 8. Around 1600 openings, each having a diameter of about 0.109 inches, are present in the pattern (A). As shown in Table 2 given above, the absorbency time for the absorbent pad having the pattern (A) of the openings 20 exceeded the absorption time of the control absorbent pad. Therefore, the pattern mode (A) is not suitable for use in an absorbent pad 10 where the take-up time is an important consideration.

The pattern (B) is a completely perforated pattern as shown in figure 9. Around 660 openings having a diameter of about 0.25 inches constitute the pattern (B) of Figure 9. Surprisingly, the pattern (B) had an improved absorption time compared to both the control absorbent pad and the pattern pad (A). It is interesting to note that the improvement of the pattern (B) over the control from the second discharge to the third discharge remained for about 25 seconds. This observation supports the theory that the open space cross section of the large openings pattern (B) had an influence on the absorption time. Initially the improvement of the absorption time of 14 seconds on the control absorbent pad could be attributed to the fact that the fluid was filling the voids created by the openings faster than absorption could occur. The improvement of 25 seconds seen in the second discharge resulted because the control remained saturated while the open volume in the openings of the pattern (B) was again open to retain the fluid and due to the improved transport of the fluid. Therefore, the same improvement for the third discharge was achieved in a similar way.

The pattern (A) taken from an absorbent article 40 of Figure 6 provided the best overall results. The four serpentine patterns of the pattern (C) comprised about 160 openings, each having a diameter of about 0.25 inches. The performance of the pattern (C) was very good as indicated by the test results. The absorption time of the pattern (C) was better than the absorption time of the pattern (B). The longitudinal transport distance for the pattern (C) was also better than the transport distance for the pattern (B) or any other pattern tested having an improved absorption time. Thus the pattern (C) shown in FIGURE 6 provided highly desirable results for use in an absorbent article.

The graphs of FIGURES 10 and 11 best show the relationship between absorption time and transport distance for the control pattern and patterns (A) - (C). In conclusion, the surface area of the apertures, the number of apertures, the depth of the apertures, the density of the pad material on one side of the apertures, especially the distance between the apertures are all important factors in the design of the aperture. an improved absorbent pad for use in absorbent articles.

Those skilled in the art will see that certain modifications can be made to the invention described herein with respect to the illustrated embodiments, without departing from the spirit of the present invention. And even though the invention has been described above with respect to the preferred embodiments, it will be understood that the invention is adapted to numerous arrangements, modifications, and alterations, all of which arrangements, modifications, and alterations are intended to fall within the scope of the appended claims. .

Claims (90)

R E I V I ND I CA C I O N S

1. - An absorbent pad for use in an absorbent article, said absorbent pad has a first length and a width, the first and second surfaces exposed to a thickness between the first and second surfaces, and an outer layer of said absorbent pad in the first surface , said outer layer being permeable to the fluid, the first surface of said absorbent pad has at least 40 openings there, the openings extend from the first surface inwards of said absorbent pad, essentially all the openings end in the bottoms of the openings respective.

2. - An absorbent pad as claimed in clause 1, characterized in that the first surface of said absorbent pad has at least 80 openings therein.

3. - An absorbent pad as claimed in clause 1, characterized in that said openings have depths of at least about 40 percent of the thickness of said absorbent pad.

4. - An absorbent pad as claimed in clause 1, characterized in that said openings have depths of from about 40 percent to about 99 percent of the thickness of said absorbent pad.

5. - An absorbent pad as claimed in clause 1, characterized in that the openings each have a cross-sectional area therethrough, from about 0.0025 square inches to about 0.25 square inches.

6. - An absorbent pad as claimed in clause 1, characterized in that the first surface defines a total surface area on a first side of the absorbent pad, the open cross-sectional area of said openings comprises from about 5 percent to about 40 percent of the total surface area of the first surface of the absorbent pad.

7. - An absorbent pad as claimed in clause 1, characterized in that the first surface defines a total surface area on a first side of the absorbent pad, the open cross-sectional area of said openings comprises from about 11 percent to about 32 percent of the total surface area of the first surface of the absorbent pad.

8. - An absorbent pad as claimed in clause 1, characterized in that the openings have lengths and widths, defining corresponding elongated shapes, the orientations of the lengths of said elongated openings correspond to the length of said absorbent pad.

9. - An absorbent pad as claimed in clause 8, characterized in that said absorbent pad has a longitudinal axis, the range of average length of said elongated openings to the length of dich absorbent pad along the longitudinal axis being d from about from 1.10 to around 1: 250.

10. - An absorbent pad as claimed in clause 1, characterized in that said aperture has an opening surface extending inwards from the absorbent pad, including along the side walls and a bottom of the respective opening, the The density of the absorbent pad near the surface of the aperture being greater than the average overall density of the absorbent pad of substantially around the total surface of the aperture.

11. - An absorbent pad as claimed in clause 1, characterized in that said openings form a pattern on the first surface of the absorbent pad, said pattern contributes to increasing the distribution of the fluid along the length of the absorbent pad in relation to the distribution of the transverse fluid to the length of said absorbent pad.

12. - An absorbent pad as claimed in clause 11, the pattern of said openings comprises a serpentine pattern, which extends along said absorbent pad.

13. - An absorbent pad as claimed in clause 11, the pattern of said openings comprises four serpentine elements extending along the length of said absorbent pad, the respective serpentine elements being separated from one another across the width of the absorbent pad.

14. - An absorbent pad as claimed in clause 11, the pattern of said openings contributes to increasing the absorption rate of the fluid of said absorbent pad.

15. - An absorbent pad as claimed in clause 1, characterized in that the openings contribute to the improved integrity of the absorbent pad.

16. - An absorbent pad as claimed in clause 1, characterized in that each bottom comprises an interior bottom surface thereof generally facing the first surface, and an outer bottom surface thereof facing away from the bottom. first surface, said outer bottom surface extending outward, in said absorbent pad from the second reference surface in the respective openings.

17. - An absorbent pad as claimed in clause 1, characterized in that said absorbent pad is located between a side-to-body liner and an outer cover.

18. - An absorbent pad for use in an absorbent article, said absorbent pad having a length of a width, the first and second opposing surfaces having a thickness between the first and second surfaces, and the openings extending from the first surface toward said interior. Absorbent pad, each opening has an opening surface extending inwardly into the absorbent pad along the thickness dimension of said absorbent pad, the density of at least a portion of said absorbent pad near the surface of the absorbent pad. opening, and extending inwardly into said absorbent pad on the side walls of the opening extending along the thickness dimension thereof, being greater than the average density of said absorbent pad around essentially the entire surface of opening.

19. - An absorbent pad as claimed in clause 18, characterized in that said absorbent pad comprises at least 80 openings.

20. - An absorbent pad as claimed in clause 18, characterized in that said absorbent pad comprises at least 40 openings.

21. - An absorbent pad as claimed in clause 18, characterized in that said openings have depths of from about 40 percent to about 99 percent of the thickness of the absorbent pad.

22. - An absorbent pad as claimed in clause 18, characterized in that the openings each have an open cross-sectional area there through, from about 0.0025 square inches about 0.025 square inches.

23. - An absorbent pad as claimed in clause 18, characterized in that the first surface defines a total surface area on the first side of the absorbent pad, the open cross-sectional area of said openings comprises from about 5 percent to about 40 percent of the total surface area of the first surface of said absorbent pad.

24. - An absorbent pad as claimed in clause 18, characterized in that the first surface defines a total surface area on the first side of the absorbent pad, the open cross-sectional area of said openings comprises from about 11 percent to about 32 percent of the total surface area of the first surface of the absorbent pad.

25. - An absorbent pad as claimed in clause 24, characterized in that the absorbent pad has a longitudinal axis, the ratio of the average length of said elongated openings to the length of said absorbent pad along the longitudinal axis being from around 1:10 to around 1: 250.

26. - An absorbent pad as claimed in clause 24, characterized in that the openings form a ern on the first surface of said absorbent pad, said ern increases the rate of fluid absorption of said absorbent pad.

27. - An absorbent pad as claimed in clause 26, characterized in that the ern of said openings comprises a serpentine ern, the serpentine ern extends along the length of said absorbent pad.

28. - An absorbent pad as claimed in clause 26, characterized in that the ern of said openings comprises four serpentine elements extending along the length of said absorbent pad, the respective serpentine elements being separated from each other across the width of said absorbent pad.

29. An absorbent pad as claimed in clause 26, characterized in that the ern of said openings contributes to increasing the distribution of the fluid along the length of the absorbent pad in relation to the distribution of the transverse fluid to the length of the absorbent pad. the absorbent pad.

30. - An absorbent pad as claimed in clause 18, characterized in that each bottom comprises an interior bottom surface thereof facing generally toward the first surface, and an exterior bottom surface thereof facing away from the bottom. First surface, said outer bottom surface extends outwardly, in said absorbent pad, from the second reference surface in the respective openings.

31. - An absorbent article characterized in that it includes an absorbent pad, as claimed in clause 18, characterized in that said absorbent pad is located between a side-to-body liner and an outer cover.

32. - An absorbent article having a front part, a back part, a crotch part connecting said front and rear parts, and a longitudinal axis extending through the front, rear and mid-leg parts, said absorbent article comprises (a) an absorbent pad having the opposite first and second surfaces and a thickness between the first and second surfaces, said absorbent pad having a multiplicity of openings there; Y (b) a side-to-body liner mounted in a surface-to-surface relationship on the first surface of said absorbent pad, said side-to-body liner being separated from the absorbent material located inwardly on said absorbent pad of the first surface, and being no more than modestly intruder in said openings.

33. - An absorbent article as claimed in clause 32, characterized in that said multiplicity of openings comprises at least 80 openings.

34. - An absorbent article as claimed in clause 32, characterized in that said multiplicity of openings comprises at least 40 openings.

35. - An absorbent article as claimed in clause 32, characterized in that said perforations have depths of from about 40 percent to about 99 percent of the thickness of said absorbent pad.

36. An absorbent article as claimed in clause 32, characterized in that said openings each have an open cross-sectional area therethrough, from about 0.0025 square inches to about 0.025 square inches.

37. An absorbent article as claimed in clause 32, characterized in that the first surface defines a total surface area on a first side of said absorbent pad, the open cross-sectional area of said openings comprises from about 5 percent to about 40 percent of the total surface area of the first surface of the absorbent pad.

38. - An absorbent article as claimed in clause 32, characterized in that said openings have lengths and widths defining the corresponding elongated shapes, the lengths of said elongated openings correspond to the length of said absorbent pad.

39. - An absorbent article as claimed in clause 38, characterized in that said absorbent article has a longitudinal axis, the ratio of the average length of said elongated openings to the length of said absorbent pad along the longitudinal axis is from around 1:10 to around 1: 250.

40. - An absorbent article as claimed in clause 32, characterized in that said openings form a pattern on the first surface of said absorbent pad, said pattern contributes to increase the rate of fluid intake of said absorbent pad.

41. - An absorbent article as claimed in clause 40, characterized in that the pattern of said openings comprises a serpentine pattern, the serpentine pattern has a pattern length, extending along the length of said absorbent pad.

42. - An absorbent article as claimed in clause 40, characterized in that the pattern of said openings comprises four serpentine elements extending along the length of said absorbent pad, the serpentine elements are spaced from each other across the width of said absorbent pad.

43. - An absorbent article as claimed in clause 40, characterized in that the pattern of said openings increase the distribution of the fluid along the length of said absorbent pad.

44. - An absorbent article as claimed in clause 32, characterized in that each of said openings has a surface of openings extending inwardly in said absorbent pad, including along said side walls and a bottom of the opening respective, the density of said absorbent pad near the opening surface is greater than the overall average density of said absorbent pad around essentially the entire surface of openings.

45. - An absorbent article as claimed in clause 32, characterized in that the body-side liner comprises a water-permeable material.

46. - An absorbent pad for use in an absorbent article, said absorbent pad has a length and a width, the first and second opposing surfaces having a thickness between the first and second surfaces, and the openings extending from the first surface inwardly in the absorbent pad, said openings forming a pattern of openings that promote the transport of the fluid along the length of said absorbent pad in relation to the transport of the fluids transverse to the length of the absorbent pad, a first of said openings being sufficiently close of a second opening to preferably pass the liquid from said first opening, along the length of the absorbent pad to the second opening by a capillary effect, thereby pulling the liquid along the length of the absorbent pad.

47. - An absorbent pad as claimed in clause 46, characterized in that the first surface of said absorbent pad has at least 80 openings therein.

48. - An absorbent pad as claimed in clause 46, characterized in that said openings have depths of at least about 40 percent of the thickness of said absorbent pad.

49. - An absorbent pad as claimed in clause 46, characterized in that the openings each have an open cross-sectional area therethrough, from about 0.0025 square inches to about 0.025 square inches.

50. - An absorbent pad as claimed in clause 46, characterized in that the first surface defines a total surface area on the first surface of said absorbent pad, the open cross-sectional area of said openings comprises from about 5 percent to about 40 percent of the total surface area of the first surface of the absorbent pad.

51. - An absorbent pad as claimed in clause 46, characterized in that each opening has "an opening surfaces extending inwardly into the absorbent pad, including along the side walls and a bottom of the respective opening, the density of said absorbent pad near the opening surface being greater than the overall average density of said absorbent pad around essentially the entire opening surface.

52. - An absorbent pad as claimed in clause 46, characterized in that said pattern of said openings comprises a serpentine pattern, the serpentine pattern having a pattern length extending along the length of said absorbent pad.

53. - An absorbent pad as claimed in clause 46, characterized in that said openings form a pattern on the first surface of said absorbent pad, said pattern contributes to increasing the distribution of the fluid along the length of the absorbent pad in Regarding the distribution of the transverse fluid to the length of the absorbent pad, said pattern comprises four serpentine elements extending along the length of said absorbent pad, the respective serpentine elements being spaced from one another across the width of said absorbent pad .

5 . - An absorbent pad as claimed in clause 46, characterized in that the pattern of said openings contributes to increasing the rate of fluid absorption of said absorbent pad.

55. - An absorbent pad as claimed in clause 46, characterized in that said openings contribute to improving the integrity of said absorbent pad.

56. - An absorbent pad for use in absorbent articles, said absorbent pad has a length and a width, the first and second opposing surfaces having a thickness between the first and second surfaces, and the openings extending from the first surface inwardly into the pad absorbent, each opening has an opening surface extending inwardly from the absorbent pad, from the first surface, the density of the absorbent pad near the surface of openings being greater than the density of said absorbent pad in places both close to each other. the first surface and away from said openings, the density of said absorbent pad near the first surface, up to a first distance from each opening, being lower than the density of said absorbent pad near the first surface of said openings, the density of said absorbent pad near the first super the first distance of said openings being greater than the density of said absorbent pad near the first surface at places of a greater distance away from the respective opening than the first distance.

57. - An absorbent pad as claimed in clause 56, characterized in that said first surface of the absorbent pad has at least 40 openings therein.

58. - An absorbent pad as claimed in clause 56, characterized in that said first surface of said absorbent pad has at least 80 openings therein.

59. - An absorbent pad as claimed in clause 56, characterized in that said openings have depths of at least about 40 percent of the thickness of the absorbent pad.

60. - An absorbent pad as claimed in clause 56, characterized in that said openings have depths of from about 40 percent to about 99 percent of the thickness of the absorbent pad.

61. - An absorbent pad as claimed in clause 56, characterized in that said openings form a pattern on the first surface of said absorbent pad, said pattern contributes to increase the distribution of the fluid along the length of the absorbent pad in relation to the distribution of the transverse fluid to the length of said absorbent pad.

62. - An absorbent pad as claimed in clause 61, characterized in that the pattern of said openings comprises a serpentine pattern, the serpentine pattern has a pattern length extending along the length of said absorbent pad.

63. - An absorbent pad as claimed in clause 61, characterized in that the pattern of said openings comprises four serpentine elements that extend along the length of the absorbent pad, the effective serpentine elements are spaced from one another through of the width of said absorbent pad.

64. - An absorbent pad as claimed in clause 61, characterized in that the pattern of said openings contributes to increasing the absorption rate of the fluid of the absorbent pad.

65. - An absorbent pad as claimed in clause 56, characterized in that said openings form a pattern, the pattern of openings being arranged so that the first of said openings are within the first distance of the second of said openings so that the fluid is directed from the first of said openings along the first surface of the absorbent pad to the second of said openings.

66. - The absorbent pad as claimed in clause 56, characterized in that said openings contribute to the improved integrity of the absorbent pad.

67. - An absorbent pad for use in an absorbent article, said absorbent pad has a first surface, a second opposing reference surface, and a thickness between the first surface and the second reference surface, the first surface of said absorbent pad having an arrangement of openings there, the openings extend from the first surface inwards of said absorbent pad, said openings end in bottoms of the respective openings, each of said bottoms comprises an interior bottom surface thereof generally facing the first surface , an outer bottom surface thereof facing away from said first surface, said outer bottom surfaces extending outwardly into said absorbent pad from the second reference surface.

68. - An absorbent pad as claimed in clause 67, characterized in that said openings have depths of from about 40 percent to about 99 percent of the thickness of said absorbent pad.

69. - An absorbent pad as claimed in clause 67, characterized in that the first surface defines a total surface area on a first side of said absorbent pad, the open cross-sectional area of said openings comprises from about 5 percent to about 40 percent of the total surface area of the first surface of said absorbent pad.

70. - An absorbent pad as claimed in clause 67, characterized in that said opening has an opening surface extending inwardly in said absorbent pad, including along the side walls and a bottom of the respective opening, the density of said absorbent pad near the surface area being greater than the overall average density of said absorbent pad of about essentially the entire surface of the opening.

71. - An absorbent pad as claimed in clause 67, characterized in that said openings form a pattern on the first surface of said absorbent pad, said pattern contributes to increase the distribution of the fluid along the length of said absorbent pad in relationship to the distribution of the transverse fluid to the length of the absorbent pad.

72. - An absorbent pad as claimed in clause 71, characterized in that the pattern of said openings comprises a serpentine pattern, the serpentine pattern has a pattern length extending along the length of said absorbent pad.

73. - An absorbent pad as claimed in clause 71, characterized in that said pattern of said openings contributes to increase the rate of fluid absorption of said absorbent pad.

74. - An absorbent pad as claimed in clause 67, characterized in that the openings contribute to the improved integrity of said absorbent pad.

75. - A method for forming an opening in an absorbent pad for use in an absorbent article the method includes the steps of: (a) directing the absorbent pad through a pressure point defined by the first and second rolls; Y (b) rotating the first and second rollers at the pressure point and therefore, using a heated bolt element, penetrating a first surface of the absorbent pad, the bolt element projecting outward from the first roller and entering a opening formed in the second roller, with the absorbent pad between the first and second roller, the action of the heated bolt element forms a pad opening and therefore effect a permanent increase in the density of the absorbent pad in an area around the periphery of the opening, whose perimeter extends into the absorbent pad from the first surface, the increased density area of the absorbent pad having greater hydrophilic properties than the non-perforated portions of the absorbent pad.

76. - A method as claimed in clause 75, characterized in that said bolt element has a dome-shaped end.

77. - A method as claimed in clause 75, characterized in that the bolt element has a flat end.

78. - A method as claimed in the clause 75, characterized in that the bolt element has a recessed end, including an eyebrow and a cavity extending from the axial brow and transversely inward at said end, the action of the tip therefore forms a pillow of material at the bottom of the opening , the pillow having an intermediate density, less than the density formed by said eyebrow and greater than the general density of the absorbent pad.

79. - A method as claimed in clause 75, characterized by including working the absorbent pad with the tip at a closed end of the respective opening.

80. - A method as claimed in clause 75, characterized in that the projection of the bolt element into the opening defines a free space between the bolt element and the sides of the opening, the free space being sufficiently small in size. relation to the thickness of the absorbent pad so that the action of the bolt element in relation to the opening works the absorbent pad and increases the density of the absorbent pad in the side portions of the opening thus formed.

81. - A method as claimed in clause 75, characterized in that the absorbent pad has sufficient thickness and strength such that the absorbent pad is pushed into the opening by the bolt element without essentially breaking the fibers of the absorbent pad .

82. - A method for distributing the liquid in an absorbent pad having the first and second opposed surfaces and a thickness therebetween, the absorbent pad includes the first, second and third openings extending inward from the first surface, the second opening being located between The first and second openings, the method, includes the steps of: (a) pulling the liquid in a longitudinal direction from the first opening, located on the first surface of the absorbent pad, towards the second opening; and (b) preferably pulling the liquid in a longitudinal direction relative to the pad from the second opening towards the third opening, the first, second and third openings comprise, in combination, a path to transport and preferably distribute the fluid in the longitudinal direction.

83. - A method as claimed in clause 82, characterized in that it includes transporting the liquid between ones of at least 40 openings in the absorbent pad.

84. - A method as claimed in clause 82, characterized in that each opening has an opening surface extending inwardly in the absorbent pad, including along the side walls and a bottom of the respective opening, the density of the absorbent pad near the surface of the opening being greater than the overall average density of the absorbent pad around essentially the entire surface of the aperture so that the greater density facilitates transmission between adjacent apertures.

85. - A method as claimed in clause 82, characterized in that the openings form a pattern on the first surface of the absorbent pad, the pattern contributes to increasing the distribution of the fluid along the length of the absorbent pad in relation to the distribution of the transverse fluid to the length of the absorbent pad.

86. - A method as claimed in clause 82, characterized in that the pattern of the openings comprises a serpentine pattern extending along the length of the absorbent pad.

87. - A method as claimed in clause 85, characterized in that the pattern of the openings comprises four serpentine elements extending along the length of the absorbent pad, the respective serpentine elements being spaced from one another through the width of the absorbent pad.

88. - A method as claimed in clause 85, characterized in that the pattern of openings contributes to increasing the fluid absorption rate of the absorbent pad.

89. - A method as claimed in clause 82, characterized in that the openings contribute to the improved integrity of the absorbent pad.

90. - A method as claimed in clause 82, characterized in that each opening has an opening surface extending inwardly in the absorbent pad, including along the side walls and a bottom of the respective opening, the density of the absorbent pad near the surface of the aperture is greater than the overall average density of the absorbent pad around essentially the entire surface of the aperture, so that transport of the liquid preferably takes place around and along the length of the aperture. the openings. SUMMARY The invention relates to absorbent pads, and to methods for manufacturing absorbent pads having improved fluid absorption and preferential transport in the longitudinal direction. The absorbent pads have patterns of openings that encourage preferential transport. The openings are characterized by the size, separation from one another, and the depth of penetration into the absorbent pad, so that the rate of fluid intake is increased and the distribution of the fluid in the longitudinal direction is improved. The openings are preferably spaced sufficiently close together so that the aqueous liquid is preferably transferred from opening to opening by the capillary effect along the length of the absorbent pad. The preferential transmission between the openings in the longitudinal direction increases the absorption rate of the overall effective liquid of the absorbent pad, thereby increasing the capacity of the general liquid of the respective absorbent article. A novel method for manufacturing an absorbent pad of the invention includes penetrating into but not through the absorbent pad using the heated pin elements. The heated bolt elements form a plurality of perforations in a first surface of the pad, the pad has a higher density near the openings than the overall density of the absorbent pad. The lower density areas of the pad have higher water absorption rates than the higher density parts of the absorbent pad.