# Patent

## Title
Method and apparatus for making absorbent structures with absorbent material

## Abstract

A method and apparatus for making specific absorbent structures with an absorbent layer with absorbent material with therein substantially longitudinally extending strips that are free of absorbent material, using or having thereto a moving endless surface with receptacle(s) with specific longitudinally extending rods; and specific absorbent structures obtained therewith, suitable for absorbent articles, such as diapers and sanitary napkins.

## Background
CROSS REFERENCE TO RELATED APPLICATION
This application claims priority to European Patent Convention Application 11169395.8, filed Jun. 10, 2011, the substance of which is incorporated herein by reference.
FIELD OF THE INVENTION
The present disclosure relates to a method for making specific absorbent structures with absorbent material, optionally with longitudinally extending strips that are free of absorbent material, and apparatus for making such absorbent structures, and specific absorbent structures obtained therewith, suitable for absorbent articles, such as diapers and sanitary napkins.
BACKGROUND OF THE INVENTION
Absorbent articles, such as diapers and sanitary napkins, absorb and contain body exudates. They also are intended to prevent body exudates from soiling, wetting, or otherwise contaminating clothing or other articles, such as bedding, that come in contact with the wearer. A disposable absorbent article, such as a disposable diaper, may be worn for several hours in a dry state or in a urine-loaded state. Accordingly, efforts have been made toward improving the fit and comfort of the absorbent article to the wearer, both when the article is dry and when the article is fully or partially loaded with liquid exudate, while maintaining or enhancing the absorbing and containing functions of the article.
Efforts have also been made to make absorbent article thinner when dry, to improve the comfort of such articles.
Some absorbent articles, like diapers, contain absorbent material such as super absorbent polymers that absorbs very high quantities of liquid and causes the absorbent article to swell significantly. Such articles will thus increase significantly in volume during use, and sometimes in particular in the crotch area between the wearer's legs, which may render the article uncomfortable.
There may thus still be a need to further improve the performance/fit of such articles and/or the liquid transportation away from the crotch. There may also still be a need to further reduce the chance of leakage and to improve the efficiency of absorbency of an absorbent article, such as a diaper.
It has been found that improved liquid transportation can be achieved by the provision of transportation channels for distributing liquid in the absorbent article, e.g., the absorbent structure thereof. Furthermore, it has been found that improved fit can be obtained by providing absorbent articles with absorbent structures wherein the absorbent material is structured in longitudinal direction, optionally with areas that comprise less or no absorbent material, for improved bending flexibility in use (in the direction corresponding to the longitudinal direction (e.g., this may be the machine direction). The present disclosure provides an apparatus and method for providing such absorbent structures, and specific absorbent structures obtained thereby.
SUMMARY OF THE INVENTION
The present disclosure provides a method of making an absorbent structure having an absorbent layer and therein longitudinally extending strips that are substantially free of absorbent material (100), said absorbent layer being supported on a supporting sheet (200), said method comprising the steps of:

    
    
        i) providing a feeder (20; 60) with absorbent material (100);
        ii) providing a moving endless surface (30), such as for example a drum, moving in a machine direction (MD) having an outer shell with one or more forming receptacles (33), having an average longitudinal dimension and length (which may be in MD) and having an average transverse dimension and width (which may be in CD), said length being more than said width, said receptacle(s) comprising a multitude of substantially longitudinally extending rods (36), spaced apart from one another in transverse direction, each rod (36) having a maximum transverse dimension which is at least 0.3 mm and each of said rods (36) having a top portion and an opposing bottom portion, said bottom portion optionally being adjacent an inner grid (37), and the minimum distance in transverse dimension between neighboring rods (36) being at least 1 mm, and said rods (36) each having an average height dimension (perpendicular to the transverse and longitudinal dimensions) of at least 1 mm,
         said moving endless surface (30) being connected to one or more vacuum systems (38) applying a vacuum suction to said receptacles (33) or part thereof,
        iii) providing a supporting sheet (200) transporter (210);
        iv) transporting said supporting sheet (200) to said outer shell, onto said top portions of said rods (36);
        v) optionally pulling said supporting sheet (200) partially in between neighboring rods (36) by said vacuum suction, to form undulations (201) in said supporting sheet (200) between said rods (36) and to form crests (202) on said upper portion of said rods (36) (as for example shown in FIG. 4);
        vi) depositing with said feeder said absorbent material (100) onto said supporting sheet (200) present on said forming receptacles (33);
        vii) pulling said absorbent material (100) with said vacuum suction onto the supporting sheet (200) that is present between neighboring rods (36), to form absorbent strips, optionally into said undulations (201);
        viii) optionally removing absorbent material (100) remaining on said crests (202) of said supporting sheet (200);
        ix) removing said supporting sheet (200) and said absorbent material (100) from said moving endless surface (30);
        to obtain said absorbent structure.
    
    


The present disclosure also provides an apparatus (1) for making an absorbent structure having an absorbent layer and therein substantially longitudinally extending strips that are substantially free of absorbent material (100), said layer being supported on a supporting sheet (200), said apparatus (1) comprising:

    
    
        a feeder for feeding an absorbent material (100) to a moving endless surface (30),
        a supporting sheet (200) transporter (210), for transporting a supporting sheet (200) to said moving endless surface (30); and
        said moving endless surface (30) moving in a machine direction (MD) having an outer shell with one or more forming receptacles (33), as mentioned above, having a multitude of substantially longitudinally extending rods (36), each rod (36) having a maximum transverse dimension of at least 0.3 mm, each of said rods (36) having a top portion (surface) and an opposing bottom portion (surface), said bottom portion being adjacent an inner grid (37), and the minimum distance in transverse dimension between neighboring rods (36) being at least 1 mm, and said rods (36) having an average height dimension (perpendicular to the transverse and longitudinal dimensions) of at least 1 mm; and
         said moving endless surface (30) comprising a vacuum system (38) applying a vacuum suction to said receptacles (33) or part thereof; or any of the dimensions as describe above; and
         said feeder optionally being a further moving endless surface (20) with reservoir(s) for receiving and retaining a said absorbent material (100) and transferring said absorbent material (100) to said moving endless surface (30), said further moving endless surface (20) being connected to a vacuum system (28) to apply vacuum suction to said reservoir(s).
    
    


In some embodiments, in step vii), said absorbent structure comprise an absorbent layer with absorbent material (100) formed into substantially longitudinally extending strips of absorbent material (100) on said supporting sheet (200), optionally in said undulations (201), with therein between strips with substantially no absorbent material (100), optionally on said crests (202).
In some embodiments, step viii) is performed; hereto the supporting sheet (200) placed on the receptacle, or the part thereof that is to overlap with the receptacle, may be wider than the width of the receptacle, so-called over-in-feeding of the supporting sheet (200) in transverse dimension, e.g. in the transverse direction, for example the Cross-machine dimension (CD). The receptacle(s) may have a first average width (e.g. in CD) dimension and said supporting sheet (200) on said receptacle (33) has a second average width dimension (e.g. in CD), and the ratio of said first to said second average width dimension is at least 1:1.1, or at least 1:1.2, or at least 1:1.3, typically up 1:3.
The method may comprise the step of providing a first adhesive application unit (50), and applying an adhesive to said absorbent layer prior to removing it from said moving endless surface (30), or immediately subsequent thereto, and/or the step of providing a second adhesive application unit (51), and applying an adhesive to said supporting sheet (200), prior to deposition of said absorbent material (100) thereon; for example, this may be done selectively, either to the areas of the supporting sheet (200) that are to meet with the rods (36), or the areas of the supporting sheet (200) that are to be in between neighboring rods (36); for example said adhesive may be applied only in substantially longitudinal stripes on the areas of said supporting sheet (200) that coincides with said crests (202).
The method may be to provide a laminate of two of said absorbent structures, e.g. the method may be such that said steps i) to vii) and ix), and optionally step vii) are repeated to form a second absorbent structure, and wherein the method comprises the subsequent step of combining said first absorbent structure and said second absorbent structure, such that said absorbent materials (100) of both structures are sandwiched between said supporting sheet (200) of the first structure and the supporting sheet (200) of the second structure.
Some or each of said rods (36) may for example have said maximum transverse dimension which is at least 1 mm, or at least 2 mm, or for example at least 3 mm or at least 4 mm, and typically up to 20 mm or up to 15 mm or up to 10 mm; the minimum distance transversely in between neighboring rods (36) may for example be at least 2 mm, or at least 3 mm, or at least 5 mm, or at least 10 mm, and for example up to 30 mm, or up to 20 mm; said rods (36) each may have an average height dimension of for example at least at least 2 mm, or for example at least 3 mm. There may for example be at least 5 rods (36), or for example at least 7 rods (36).
The method may comprise the step of providing a pressure roll (70) with a raised pressure pattern (71), corresponding to the pattern of said rods (36) and/or said crests (202) if present, and mating said pressure roll (70) pattern with said absorbent structure, on the supporting sheet thereof, and/or on a further material, after such a further material is superposed on said absorbent layer, (e.g. the supporting sheet (200) is folded over it, a further supporting sheet (300) is placed on it, or and acquisition layer is placed on it, or a further absorbent structure is placed on it, such that the absorbent material (100) is sandwiched between the two supporting sheets (200; 300), wherein said pressure pattern (71) mates with said supporting sheet (200), or said further material, in the areas where, on the opposite surface, no absorbent material (100) is present
Said feeder is adjacent and in close proximity to said moving endless surface (30), and they transfer of said absorbent material (100) takes place in a so-called meeting point. The feeder may be a further moving endless surface (20) with reservoir(s), such as a so-called print roll, and said method may comprise the steps of receiving absorbent material (100) on said further moving endless surface (20), retaining said absorbent material (100) in said reservoir(s) and transferring said absorbent material (100) to said moving endless surface (30); optionally said further moving endless surface's reservoir being formed by a multitude of grooves or a multitude of rows of cavities (22), each groove or row extending substantially longitudinally, said grooves or rows may be spaced from one another with raised strips. The method may comprise the step that said raised strips and said rods (36) are mating during the transfer of said absorbent material (100), e.g. in said meeting point.
Said receptacle (33) may have a front edge zone, and back edge zone, each extending the width/transverse dimension of said receptacle, and said front edge zone and/or back edge zone do not comprise said rods (36), with therein between a central zone with rods (36); or wherein said receptacle (33) has a centre region, front region and back region, and said receptacle (33) comprises said rods (36) in said front region only, or in said centre region only, or in said front and centre region only. Said receptacle (33) may have in said region(s) or zone(s) that not comprising said rods (36) a higher friction than said rods (36).
For example, as also shown in FIG. 6 for example, said central zone (B) having said rods, having a lower friction than said front edge zone and back edge zones (A; C) without rods. This can aid to ensure the supporting sheet (200) is pulled in between the rods (36) in the low friction zone, and less or not at all in the high friction zone.
The apparatus (1) may comprises additional units, such as a unit (300) to cover the absorbent structure's absorbent layer with a further material, as described herein; and/or an adhesive application unit (51) upstream from said moving endless surface (30), and/or a adhesive application unit (50), positioned downstream of the point where the feeder and said moving endless surface (30) meet (meeting point); and/or a pressure roll (70) with a raised pressure pattern (71), as described herein.
The present disclosure also relates to absorbent structures obtainable with the method or apparatus (1) herein, in particular those where the absorbent layer comprises such strips that comprise no absorbent material (100), and/or wherein said supporting sheet (200) comprises said undulations (201) with absorbent material (100) and crests, not comprising absorbent material (100), and/or wherein an adhesive is applied to immobilize said absorbent material (100), and/or wherein said absorbent structure comprises a further material on said absorbent layer, e.g. another absorbent structure, further supporting sheet (300) or acquisition layer, and a pressure is applied, to pressurize said supporting sheet (200) (further) into said strips where no absorbent material (100) is present, to render said strips more permanent in use.
The absorbent material (100), e.g. including or being a particulate superabsorbent polymer material, may be deposited on the supporting sheet (200) such that the absorbent layer comprises or consists of absorbent material (100) strips, extending substantially in the longitudinal direction, with therein between strips with no absorbent material (100), e.g. in the form of an absorbent layer with absorbent material (100) with therein substantially longitudinally extending strips that are free of absorbent material (100); such strips without absorbent material (100) may for example only extend at the most 90% or at the most 80%, or for example at the most 70% or for example at the most 60% of the full length of the absorbent layer. Said strips without absorbent are material may optionally have an average width dimension of at least 2 mm, or at least 3 mm; said strips may have any of the dimensions and shapes and positions described herein for said rods (36) and/or raised portions.
It should be understood that above and following description applies equally to the method and the apparatus (1) of the present disclosure, and the absorbent structure obtained therewith, unless stated otherwise.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of an apparatus of the present disclosure.
FIG. 2 is a perspective view of an apparatus of the present disclosure.
FIG. 3 is a perspective view of optional further units of the apparatus of the present disclosure, combining absorbent structures into an absorbent article and bonding it.
FIG. 4 is a partial and cross-sectional view of a moving endless surface and a receptacle thereof, of an apparatus of the present disclosure.
FIG. 5 is a top view of a receptacle during production of an absorbent structure herein.



DETAILED DESCRIPTION OF THE INVENTION
As summarized above, this invention encompasses a method and apparatus (1) for making an absorbent structure useful for absorbent article comprising absorbent material (100), optionally at least, or only, particulate superabsorbent polymer material, and preferred absorbent layers. Embodiments of such method and apparatus (1) and resulting absorbent structures and absorbent articles are further described herein below, after the following definitions.
Definitions
“Absorbent structure” refers to a three-dimension structure with a longitudinally dimension and perpendicular thereto a transverse dimension and perpendicular to both a height dimension, and that comprises at least an absorbent material (100) and a supporting sheet (200), and that is useful in an absorbent article.
“Absorbent layer” refers to a three dimensional layer of absorbent material (100), formed by deposition of absorbent material (100) (s) onto the supporting sheet (200), and it may comprise other components, e.g. deposited onto the supporting sheet (200).
“Absorbent material (100)” refers to a material or mixture of materials that can absorb and retain bodily fluids; it typically includes or consists of Superabsorbent polymer material”. “Superabsorbent polymer material” (also known as “absorbent gelling material,” or “AGM,” “superabsorbent,”) refer to polymeric materials that can absorb at least 10 times their weight of an aqueous 0.9% saline solution as measured using the Centrifuge Retention Capacity test (Edana 441.2-02) i.e. having a CRC of at least 10 g/g. This is typically in particulate form.
“Particulate” is used herein to refer to a material which is in particulate form so as to be flowable in the dry state.
“Absorbent article” refers to a device that absorbs and contains body exudates, and, more specifically, refers to devices that are placed against or in proximity to the body of the wearer to absorb and contain the various exudates discharged from the body. Absorbent articles may include adult and infant diapers, including pants, such as infant training pants and adult incontinence undergarments, and feminine hygiene products, such as sanitary napkins and panty-liners and adult in continent pads, and breast pads, care mats, bibs, wound dressing products, and the like. Absorbent articles may further include floor cleaning articles, food industry articles, and the like. As used herein, the term “body fluids” or “body exudates” includes, but is not limited to, urine, blood, vaginal discharges, breast milk, sweat and fecal matter.
“Diaper” refers to an absorbent article generally worn by infants and incontinent persons about the lower torso so as to encircle the waist and legs of the wearer and that is specifically adapted to receive and contain urinary and fecal waste.
“Pant” or “training pant”, as used herein, refer to diaper having a waist opening and leg openings designed for infant or adult wearers. A pant may be placed in position on the wearer by inserting the wearer's legs into the leg openings and sliding the pant into position about a wearer's lower torso. A pant may be preformed by any suitable technique including, but not limited to, joining together portions of the article using refastenable and/or non-refastenable bonds (e.g., seam, weld, adhesive, cohesive bond, fastener, etc.). A pant may be preformed anywhere along the circumference of the article (e.g., side fastened, front waist fastened). While the terms “pant” or “pants” are used herein, pants are also commonly referred to as “closed diapers,” “prefastened diapers,” “pull-on diapers,” “training pants,” and “diaper-pants”. Suitable pants are disclosed in U.S. Pat. No. 5,246,433, issued to Hasse, et al. on Sep. 21, 1993; U.S. Pat. No. 5,569,234, issued to Buell et al. on Oct. 29, 1996; U.S. Pat. No. 6,120,487, issued to Ashton on Sep. 19, 2000; U.S. Pat. No. 6,120,489, issued to Johnson et al. on Sep. 19, 2000; U.S. Pat. No. 4,940,464, issued to Van Gompel et al. on Jul. 10, 1990; U.S. Pat. No. 5,092,861, issued to Nomura et al. on Mar. 3, 1992; U.S. Patent Publication No. 2003/0233082 A1, entitled “Highly Flexible And Low Deformation Fastening Device”, filed on Jun. 13, 2002; U.S. Pat. No. 5,897,545, issued to Kline et al. on Apr. 27, 1999; U.S. Pat. No. 5,957,908, issued to Kline et al on Sep. 28, 1999.
A “nonwoven” is a manufactured sheet, web or batt of directionally or randomly orientated fibers, bonded by friction, and/or cohesion and/or adhesion, excluding paper and products which are woven, knitted, tufted, stitch-bonded incorporating binding yarns or filaments, or felted by wet-milling, whether or not additionally needled. The fibers may be of natural or man-made origin and may be staple or continuous filaments or be formed in situ. Commercially available fibers have diameters ranging from less than about 0.001 mm to more than about 0.2 mm and they come in several different forms: short fibers (known as staple, or chopped), continuous single fibers (filaments or monofilaments), untwisted bundles of continuous filaments (tow), and twisted bundles of continuous filaments (yarn). Nonwoven fabrics can be formed by many processes such as meltblowing, spunbonding, solvent spinning, electrospinning, and carding. The basis weight of nonwoven fabrics is usually expressed in grams per square meter (gsm).
“Substantially cellulose free” is used herein to an absorbent layer structure (or core), that contains less than 5% by weight cellulosic fibers.
“Thickness” and “height” are used herein interchangeably.
A absorbent structure and absorbent layer thereof, and a receptacle (33) herein each have a longitudinal dimension and average length, and this may be corresponding the machine direction (MD), and perpendicular thereto a transverse dimension, and average width, which may be corresponding to the cross-machine direction (CD), said width being less than said length; and a front region, back region and central region, each being 1⁄3 of the average length of the structure/layer, respectively, and having each the full width. Each has longitudinal edges and edge zones, extending the full length thereof—as further described below.
Moving Endless Surface (30)
The method and apparatus (1) herein deploy a moving endless surface (30), moving in a machine direction (MD). It has an outer shell with one or more forming receptacles (33), for receiving thereon or therein the supporting sheet (200) (which may be a web material, as described herein below, or individual sheets that are placed on a receptacle). The following is described for a single receptacle (33) but may apply to each receptacles (33) of the moving endless surface (30)'s outer shell. An exemplary apparatus is shown in FIG. 1.
Each receptacle (33) corresponds typically to an absorbent structure to be produced, as suitable for an absorbent article. The supporting sheet (200) may be a web material, so the method and apparatus (1) herein can thus serve to produce a web of such absorbent structures that are then subsequently separated into individual structures.
The moving endless surface (30) may have or be a rotating surface, such as a rotating, e.g. cylindrical, drum. It may be that the outer shell moves, e.g. rotates, around a stationary inner chamber, e.g. a so-called stator (230).
The outer shell and the receptacle (33) have a transverse direction and average transverse dimension (average width), and the receptacle (33) has longitudinal direction and average longitudinal dimension (average length), perpendicular thereto.
The receptacle (33) has peripheral edges, and peripheral edge zones, including opposing longitudinal edges and edge zones, and a transverse front edge and front edge zone A, and a transverse back edge and back edge zone C, with a central zone B in between. Each of said front and back edge zones, extending the complete transverse dimension, may for example be in longitudinal dimension from about 5% to about 20%, or to 15%, or to 10% of the average longitudinal dimension of the receptacle.
Each of said longitudinal edge zone may extend the length and may have an average transverse dimension of for example from about 5% to about 20%, or typically to about 15% or to about 10% of the average transverse dimension of the receptacle.
The receptacle (33) may in addition, or alternatively, comprise a front region, back region and central region, therein between, as further described below. The central region may be for example the central 1⁄3 of the receptacle, extending the full transverse dimension.
The receptacle (33) comprises a multitude of substantially longitudinally extending rods (36), spaced apart from one another in transverse direction. The rods (36) are such that they form or partially form the most outer surface of said receptacle, so that the supporting sheet (200) is received and carried by said rods (36). Thus, between rods (36) there is a spacing where the supporting sheet (200) may not be supported directly by the receptacle, or may not be in direct contact with the receptacle. For example, FIG. 2 shows such a receptacle, and FIG. 4 shows a cross-section thereof.
The receptacle (33) may comprise said rods (36) over substantially the whole length of the receptacle; or for example over the whole length except the front edge zone and/or back edge zone; or, in some embodiments herein, the rods (36) may be present only in said central region; in some embodiments, the rods (36) may be present in the front region and optionally the central region, but not the back region; in some embodiments, the rods (36) may be present in the back region and optionally the central region, but not the front region.
The receptacle (33) may comprise such rods (36) over the whole width of said receptacle; or for example over the whole width except in said longitudinal edge zones.
In any of these embodiments, the zone(s) or region(s) not comprising said rods (36) is herein referred to as rod-free zone or rod-free region; in said rod-free region or rod-free zone the supporting sheet (200) may be deposited onto said inner grid (37) (e.g. a mesh material) directly, or there may be an outer grid present, typically in the same plane as the rods (36); for example an outer grid made of a combination of transverse and longitudinal rods (36) that are intersecting in the same plane, like a mesh), or a plate with optionally apertures for vacuum suction. This is for example shown in FIG. 4.
Said receptacle (33) may have in said region(s) or zone(s) that not comprising said rods (36) a higher friction than aid rods (36). This can aid to ensure the supporting sheet (200) is pulled in between the rods (36) in the low friction zone, and less or not at all in the high friction zone. For example, the receptacle (33) can be made of a higher friction material (e.g. a material with a less even surface), or may be treated with an friction-increasing agents, in those zones or regions not comprising said rods (36); or for example said zones or regions with rods (36), or only said rods (36), can be made of a lower friction material, or treated with friction-reducing agent.
A rod (36) is considered substantial longitudinally extending, if its longitudinal (length) extension is more than its transverse (width) extension. Thus, a rod (36) may be under an angle with the longitudinal axis of the receptacle, provided said angle is less at the most 30°; or a rod (36) may be slightly curved (as described below); or a rod (36) may be wavy; or a rod (36) may comprise an angle, provided said angle is at least 120°, as described below; provided, in each case, its longitudinal (length) extension is more than its transverse (width) extension, e.g. they extend at least 50% or at least 100% more in longitudinal dimension of said receptacle (33) than in transverse dimension.
The rod (36) may be any shape or form. It may have a square, rectangular, round, oval or hexagonal cross-section in transverse dimension, for example. Each rod (36) has a top portion (which may be the top surface for, for example, rods (36) that have a square or rectangular cross-section) and an opposing bottom portion or surface. Said top portion or surface is then in contact with the supporting sheet (200); said bottom surface may be adjacent (e.g.: on) an, at least partially, air-permeable inner grid (37).
In some embodiments, it may be preferred that the rod (36) is generally rectangular with optionally a triangular-shaped top portion.
Neighboring rods (36) are spaced apart, e.g. with a minimum distance (transversely) of for example at least 2 mm, or at least 3 mm, or at least 5 mm, or for example at least 10 mm.
Two or more rods (36) may be parallel to one another, so that the spacing distance between parallel neighboring rods (36), transversely, is at least said 2 mm along substantially the whole length.
Thus, there is a void volume neighboring rods (36), e.g. between the inner grid (37) if present, and neighboring rods (36), and said void volume extends substantially in longitudinal direction in between said neighboring rods (36).
This void volume can serve to receive the supporting sheet (200) therein, as an undulation, and optionally said absorbent material (100).
Each rod (36) has a maximum transverse dimension which may be at least 0.3 mm, optionally at least 0.5 mm, or at least 1.0 mm, or at least 2 mm, and in some embodiments, for example at least 3 mm or at least 4 mm, and for example up to 20 mm, or up to 15 mm or for example up to 10 mm.
Each rod (36) has a maximum and average height dimension. Each rod (36) may for example have an average or maximum height dimension of at least 2 mm, or at least 3 mm, or at least 4 mm, or at least 5 mm.
This may be optionally substantially equal to the distance from the top of a rod (36) to the inner grid (37), if present.
The receptacle (33) may for example have at least 2 such rods (36), or for example at least 4 such rods (36), or for example at least 5 or at least 7 such rods (36).
The rods (36) may be slightly curved (for example having a single curvature), having a curvature with a radius that is at least equal to, optionally at least 1.5 times or at least 2 times, the average transverse dimension of the receptacle; and/or having a curvature following for example the contour of the closest longitudinal side edge; and/or having multiple small curvatures, said rod(s) being then for example longitudinally extending wavy rod(s). In any such case, said rods (36) are considered to extend substantially longitudinally, as said out above.
In some embodiments the rods (36) are straight and parallel to the longitudinal axis of the receptacle.
In some embodiments it may be preferred that the rods (36) are concave, wherein the longitudinal centre of the rod (36) is closer to the longitudinal axis of the receptacle (33) than the end point(s), and wherein the radius of curvature is at least 1.5 times the transverse dimension of the receptacle, optionally at least 2 times.
The moving endless surface (30) is connected to a vacuum system (38) that can apply a vacuum on said outer shell/receptacles (33), to pull the supporting sheet (200) onto said outer shell/receptacles (33), and to retain the absorbent material (100) thereon. The moving endless surface (30) may thus move adjacent a vacuum system, such as a vacuum chamber (s) (38), that is present adjacent the outer shell (on the opposite side to the rods (36)). The vacuum chamber(s) may be present in a stator (230) around which the moving endless surface (30) rotates.
The outer shell is hence at least partially air-permeable, which means it is such that it in air communication with said vacuum system, e.g. provided affective vacuum pressure can be applied through said shell onto said supporting sheet (200). For example, the rods (36) themselves may for example not be air-permeable, i.e. not being in direct air communication with said vacuum system. The surface area between rods (36) should however generally be air-permeable. Hence, the inner grid (37) may be air-permeable, e.g. it may be a mesh material, for example.
In some preferred embodiments, the supporting sheet (200) is deposited onto said rods (36) and it bends in between neighboring rods (36), e.g. due to the vacuum suction to form thereby in said sheet undulations (201) between neighboring rods (36), and crests (202) supported on said rods (36) (on said top surface or top portion). The inner grid (37) may control/determine the size (height) of said undulations (201). This is for example shown in FIGS. 4 and 5.
The supporting sheet (200) is transferred from a transfer means, such a transfer roll, to said moving endless surface (30) and deposited onto said outer surface/receptacles (33), e.g. onto said rods (36) at least. It may be transported to the outershell and receptacles (33) thereof as a web, or as individual sheets.
The supporting sheet (200) may be a nonwoven material, as further described herein. Subsequently, said absorbent material (100) may be deposited onto said supporting sheet (200), on said receptacles (33). The absorbent material (100) may be deposited such that it is only present on the portions (e.g. strips) of the supporting sheet (200) that is present between neighboring rods (36), e.g. in said undulations (201). Thereto, specific feeders as described below may be used. Alternatively, or in addition, the vacuum may be such that it pulls the absorbent material (100) to or towards the portions of the supporting sheet (200) present between neighboring rods (36), e.g. into said undulations (201). Substantially no absorbent material (100) may for example be present on the supporting sheet (200) present on said rods (36), e.g. on said crests, as for example shown in FIGS. 4 and 5.
Alternatively, or in addition, absorbent material (100) deposited onto the portions of the supporting sheet (200) on said rods (36) (e.g. said crests (201)) may be removed by means known in the art, such as a scraper or doctor blade.
Alternatively, or in addition, the supporting sheet (200) may comprise adhesive. For example said adhesive may be present on said portions of said supporting sheet (200) that are between neighboring rods (36), e.g. said undulations (201). This may help to adhere the absorbent material (100) in such portions, e.g. on said undulations (201). The supporting sheet (200) may then, prior to addition of the absorbent material (100), comprise no adhesive applied on said portions supported by said rods (36), e.g. said crests (202), so that less or no absorbent material (100) adheres in said portions, e.g. crests. This is for example shown in FIG. 1.
By use of these rods (36), the absorbent structure may have said absorbent material (100) deposited in the form of strips of absorbent material (100) (e.g. corresponding to said undulations (201)), with therein in between strips that are free of such absorbent material (100) (e.g. corresponding to aid crests (202)); and/or said absorbent layer formed herein may be a layer of absorbent material (100) with strips that are substantially free of absorbent material (100) (e.g. the crests (202) of said supporting sheet (200)).
As described above, the supporting sheet (200) may be transferred to said moving endless surface (30) such that it forms undulations (201) and crests (202). Then, when the supporting sheet (200) is removed from said moving endless surface (30), the supporting sheet (200) is pulled substantially flat, resulting in an absorbent structure with substantially longitudinally extending strips (that correspond to the crests (202) of said material) that comprise substantially no absorbent material (100). This is for example shown in FIG. 5.
In some embodiments, the moving endless surface (30) may for example have a speed of at least 1000 part per minute and/or a speed of at least 4.5 m/s, or at least 6 m/s, or at least 8 m/s.
Feeder (20; 60)/Further Moving Endless Surface (20)
The absorbent material (100) may be delivered to the supporting sheet (200) by a feeder (60; 20) placed adjacent and in close proximity to said moving endless surface (30), for example substantially above said surface.
The absorbent material (100) may be deposited onto said supporting sheet (200) by any method, including substantially continuously.
The feeder herein is capable of holding the absorbent material (100), and letting it flow to the supporting sheet (200) on said moving endless surface (30). The point or area where the material leaves the feeder is herein referred to as meeting point.
The feeder may be a (e.g. stationary) hopper (60) with a container portion, to hold the material, e.g. having a volume of at least 1000 cm3, and a guiding portion, e.g. a pipe-shapes portion, having one or more walls that guides the material from the container portion to the supporting sheet (200) on the moving endless surface (30).
In a preferred embodiment, the absorbent material (100) is deposited on the supporting sheet (200) carried on said moving endless surface (30) by a further moving endless surface (20) that moves, moving in a machine direction, e.g. rotates, adjacent and in close proximity to said moving endless surface (30). In such a case, a hopper (60), as for example described above, may feed the absorbent material (100) to this further moving endless surface (20).
The further moving endless surface (20) may be a rotating device. The further moving endless surface (20) is typically a rotating device with a certain radius, such as a cylinder or drum or print roll, as for example shown in the Figures. The radius of the further moving endless surface (20) may depend on what absorbent structure is produced, e.g. what size, and for example how many structures are produced per cycle of the further moving endless surface (20), e.g. print roll or drum. For example, the drum/print roll may have a radius of at least 40 mm, or of at least 50 mm; it may be for example up to 300 mm, or up to 200 mm.
The further moving endless surface (20) may have any suitable width, but for example a width corresponding to the width of the absorbent structure to be produced; this for example be at least 40 mm, or at least 60 mm, or for example up to 400 mm, or up to 200 mm.
Said further moving endless surface (20) may have one or more reservoirs with a certain volume for receiving said absorbent material (100) therein, and transporting it and then depositing it to said supporting sheet (200) on the moving endless surface (30) with receptacle(s) with rods (36), described above.
Such a reservoir may then correspond to an absorbent structure to be produced. The reservoir may have a (average) longitudinal dimension, and (average) length, and a (average) transverse dimension and (average) width, said length being more than said width.
The reservoir may have raised strips (that have no void volume) and then, when the further moving endless surface (20) moves (rotates) adjacent said moving endless surface (30) with said supporting sheet (200) on said rods (36), said raised portions may mate with (correspond to) said rods (36) (herein referred to as “mating”). Then, the absorbent material (100) is deposited selectively between rods (36), e.g. in said undulations (201).
In some embodiments, the reservoir is composed of multitude of groves, extending substantially longitudinally, or a multitude of rows of cavities (22), extending, for receiving the absorbent material (100) therein, wherein neighboring grooves or rows are being separated from one another by such raised strips that do not have a void volume for receiving absorbent material (100).
Then, typically, the raised strips move adjacent (mate) said rods (36) and said crests (202) of said supporting sheet (200), and the grooves or rows of cavities (22) move adjacent (mate) with said areas of the supporting sheet (200) between neighboring rods (36), e.g. said undulations (201). Then, the absorbent material (100) is deposited selectively between rods (36), e.g. in said undulations (201).
The resulting absorbent structure then comprises a supporting sheet (200) with thereon a layer of absorbent material (100) with substantially longitudinally extending strips that comprise no absorbent material (100).
The cavities (22) may have any dimensions and shape, including cubical, rectangular, cylindrical, semi-spherical, conical, or any other shape. This may be any suitable number of cavities (22), but for example at least 20 or at least 50.
The cavities (22) may be present as identical cavities (22) or they may vary in dimension(s) or shape. The exact pattern, dimensions etc. will depend on the required structure to be formed, but may for example also depend on the particle size of the absorbent material (100), process speed etc. In some embodiments at least 30% of the surface area of the reservoir of the further moving endless surface (20) comprises said cavities (22), optionally at least 40%, and optionally up to 55% or up to 50%.
The distance (longitudinally) between the centre point of a cavity (said centre point being in the plane of the outer surface of the further moving endless surface (20)) and the centre point of a neighboring cavity (in a row of cavities (22)) may for example be at least 3 mm, or at least 4 mm, or at least 6 mm, or for example up to 40 mm or up to 30 mm or up to 20 mm. This may apply to all such distances between neighboring cavities (22) longitudinally, or this may be an average over all such distances.
The distance transversely between the centre point of a cavity or groove (said centre point being in the plane of the outer surface of the further moving endless surface (20)) and the centre point of a neighboring cavity or groove (in a transverse line of cavities (22)) may for example also be as above. In some embodiments, the shortest distance transversely between two neighboring cavities (22) of a line of cavities (22) or between neighboring groves is at least 3.0 mm, or at least 4.0 mm, so that this can mate with the rods (36) of the moving endless surface (30).
Said rows or grooves may extend substantially parallel to, and equally spaced from, one another and/or said lines may extend substantially parallel to, and equally spaced from, one another.
In some embodiments, the grooves and rows have such a shape or pattern, that the distance between neighboring groves or rows is substantially corresponding to a rod; and/or that the grooves or rows correspond substantially to the areas between neighboring rods (36). Then the grooves or rows can mate with the areas between rods (36).
In some embodiments, the length dimension of a cavity may be (on average over all cavities (22) and/or for each cavity; measured over the outer surface of the further moving endless surface (20)) at least 1 mm, or at least 2 mm, or at least 4 mm, and for example at the most 20 mm or at the most 15 mm. The width dimension may be within the same ranges as above, or it may even be the same as the length dimensions for one or more or each cavity.
In some embodiments, a raised portion is completely overlapping a corresponding rod.
In some embodiments, the average width dimension of each raised portions of the reservoir(s) that mates with a rod (36) is about at least 10% more than the average width dimension of said rod.
The reservoir, cavities (22) or grooves may have any suitable dept dimension, and it may depend for example on the height of the further moving endless surface (20) (e.g. radius), the thickness/caliper of the desired structure to be produced, the particle size of the material, etc. The maximum depth of a reservoir, cavities (22) or grooves and/or the average maximum depth (average over all maximum depths of all cavities (22) and/or grooves) may for example be at least 1 mm, or at least 1.5 mm, or for example 2 mm or more, and for example up to 20 mm, or up to 15 mm, or in some embodiment herein, up to 10 mm, or to 5 mm, or to 4 mm.
According to some embodiments herein, the cavities (22) may have a an average width dimension and length dimension of from 2 to 8 mm or from 3 mm to 7 mm; and the cavities (22) may have a maximum depth and/or average maximum depth of for example from 1.5 mm to 4 mm.
A scraper or doctor blade may be used to remove excess absorbent material (100). Excess material may be removed from the reservoir and recycled back to e.g. the hopper
One possibility to hold the material in the reservoir (or its groves or cavities (22)) may be a vacuum (28) applied to the inner side of the further moving endless surface (20), e.g. print roll or drum, in combination with suction holes in (the bottom) of the reservoir, or groves cavities (22) thereof, to thus apply the vacuum suction onto the absorbent material (100). The vacuum is for example released just before or at the meeting point. The vacuum may be any vacuum pressure such as, just as for the moving endless surface (30) above, for example at least 10 kPa, or at least 20 kPa.
The vacuum may be provided by providing one or a plurality of vacuum chambers (28) in said further moving endless surface (20) (e.g. in its interior), wherein said vacuum can be applied, reduced, increased, and released (disconnected), depending on the position thereof in the process/apparatus (1).
Additional air pressure and air pressure chamber(s) (29) may be used/applied to said absorbent material (100) close to or at the meeting point, to ensure that the material flows to the supporting sheet (200) on said moving endless surface (30).
Absorbent Material (100)
The absorbent material (100) herein is optionally a flowable material (in the dry state), such as a particulate material; it may be any material in particulate form, which includes particles, flakes, fibers, spheres, agglomerated particles and other forms known in the art. The absorbent material (100) may be a mixture of cellulose material, or so-called airfelt, and superabsorbent polymer material.
Alternatively, or in addition, when two absorbent structures are combined as described herein, the first absorbent structure may comprise a first absorbent material (100), and the second structure may comprise a second, different absorbent material (100), for example having a different capacity (CRC).
In some embodiments herein, the absorbent material (100), e.g. the particulate absorbent material (100), comprises at least or consists of (particulate) superabsorbent polymer material, herein referred to as SAP, and also known as particulate absorbent gelling material, AGM. The particulate SAP herein may have a high sorption capacity, e.g. having a CRC of for example at least 20 g/g, or at 30 g/g. Upper limits may for example be up to 150 g/g, or up to 100 g/g.
The particulate SAP may have a good permeability for liquid, for example, having a SFC value of at least 10×10−7 cm3 s/g; or optionally at least 30×10−7 cm3·s/g, or at least 50×10−7 cm3s/g 10×10−7 cm3s/g, or possibly permeability SFC value of at least 100×10−7 cm3s/g, or at least a SFC of 120×10−7 cm3sec/g. This SFC is a measure of permeability and an indication of porosity is provided by the saline flow conductivity of the gel bed as described in U.S. Pat. No. 5,562,646, (Goldman et al.) issued Oct. 8, 1996 (wherein however a 0.9% NaCl solution is used instead of Jayco solution). Upper limits may for example be up to 350 or up to 250 (×10−7 cm3·s/g).
In some embodiments herein the polymers of said SAP are internally cross-linked and/or surface crosslinked polymers.
In some embodiments herein, the absorbent material (100) comprising or consisting of particles of polyacrylic acids/polyacrylate polymers, for example having a neutralization degree of from 60% to 90%, or about 75%, having for example sodium counter ions, as known in the art, e.g. surface crosslinked and/or internally crosslinked and/or post-crosslinked polyacrylic acid/polyacrylate polymers.
In some embodiments herein, the absorbent material (100) is in the form of particles with, a mass medium particle size up to 2 mm, or between 50 microns and 2 mm or to 1 mm, or optionally from 100 or 200 or 300 or 400 or 500 μm, or to 1000 or to 800 or to 700 μm; as can for example be measured by the method set out in for example EP-A-0691133. In some embodiments of the present disclosure, the material is in the form of particles whereof at least 80% by weight are particles of a size between 50 μm and 1200 μm and having a mass median particle size between any of the range combinations above. In addition, or in another embodiment of the present disclosure, said particles are essentially spherical. In yet another or additional embodiment of the present disclosure the absorbent material (100) has a relatively narrow range of particle sizes, e.g. with the majority (e.g. at least 80% or optionally at least 90% or even at least 95% by weight) of particles having a particle size between 50 μm and 1000 μm, optionally between 100 μm and 800 μm, and more optionally between 200 μm and 600 μm.
The absorbent material (100) herein may advantageously comprise less than 15% by weight of water, or less than 10%, or less than 8% or less than 5%. The water-content can be determined by the Edana test, number ERT 430.1-99 (February 1999) which involves drying the particulate material (100) at 105° Celsius for 3 hours and determining the moisture content by the weight loss of the particulate material (100) after drying.
The particulate SAP herein may be particles of SAP that are surface coated or surface treated (this not including surface-crosslinking, which may be an additional surface-treatment); such coatings and surface treatment steps are well known in the art, and include surface treatment with one or more inorganic powders, including silicates, phosphates, and coatings of polymeric material, including elastomeric polymeric materials, or film-forming polymeric materials.
Supporting Sheet (200)
The absorbent structure producible with the apparatus (1) and method of the present disclosure comprises a supporting sheet (200), to receive the absorbent material (100). This supporting sheet (200) may be any individual sheet or web sheet material, in particular paper, films, wovens or nonwovens, or laminate of any of these.
In some embodiments herein, the supporting sheet (200) is a nonwoven, e.g. a nonwoven web, such as a carded nonwoven, spunbond nonwoven or meltblown nonwoven, and including nonwoven laminates of any of these.
The fibers may be of natural or man-made origin and may be staple or continuous filaments or be formed in situ. Commercially available fibers have diameters ranging typically from less than about 0.001 mm to more than about 0.2 mm and they come in several different forms: short fibers (known as staple, or chopped), continuous single fibers (filaments or monofilaments), untwisted bundles of continuous filaments (tow), and twisted bundles of continuous filaments (yarn). The fibers may be bicomponent fibers, for example having a sheet-core arrangement, e.g. with different polymers forming the sheet and the core. Nonwoven fabrics can be formed by many processes such as meltblowing, spunbonding, solvent spinning, electrospinning, and carding. The basis weight of nonwoven fabrics is usually expressed in grams per square meter (gsm).
The nonwoven herein may be made of hydrophilic fibers; “Hydrophilic” describes fibers or surfaces of fibers, which are wettable by aqueous fluids (e.g. aqueous body fluids) deposited on these fibers. Hydrophilicity and wettability are typically defined in terms of contact angle and the strike through time of the fluids, for example through a nonwoven fabric. This is discussed in detail in the American Chemical Society publication entitled “Contact angle, wettability and adhesion”, edited by Robert F. Gould (Copyright 1964). A fiber or surface of a fiber is said to be wetted by a fluid (i.e. hydrophilic) when either the contact angle between the fluid and the fiber, or its surface, is less than 90°, or when the fluid tends to spread spontaneously across the surface of the fiber, both conditions are normally co-existing. Conversely, a fiber or surface of the fiber is considered to be hydrophobic if the contact angle is greater than 90° and the fluid does not spread spontaneously across the surface of the fiber.
The supporting sheet (200) herein may be air-permeable. Films useful herein may therefore comprise micro pores. Nonwovens herein may for example be air permeable. The supporting sheet (200) may have for example an air-permeability of from 40 or from 50, to 300 or to 200 m3/(m2×min), as determined by EDANA method 140-1-99 (125 Pa, 38.3 cm2). The supporting sheet (200) may alternatively have a lower air-permeability, e.g. being non-air-permeable, to for example be better detained on a moving surface comprising vacuum.
In preferred executions, the supporting sheet (200) is a nonwoven laminate material, a nonwoven laminate web, for example of the SMS or SMMS type.
In order to form easily said undulations (201), the supporting sheet (200) may have a basis weight that is less than 60 gsm, or for example than 50 gsm, for example from 5 gsm to 40 gsm, or to 30 gsm.
Adhesive Application Units and Method Steps.
The supporting sheet (200) may comprise and adhesive prior to transfer to said moving endless surface (30). Thus, the apparatus (1) herein may comprise an adhesive application unit (51) upstream from said moving endless surface (30), and for example downstream from said supporting material transfer means (210), e.g. roll. The method herein may thus comprise such an adhesive application step. This is for example shown in FIG. 1.
This adhesive may be applied uniformly and/or continuously.
It may be applied as substantially longitudinal stripes. For example, the adhesive may be applied in substantially longitudinally extending stripes such that areas of the supporting sheet (200) with the stripes of adhesive are between neighboring rods (36), and the areas of the supporting sheet (200) that do not comprise said adhesive correspond to said rods (36), or the opposite.
In some embodiments, the apparatus (1) may comprise a unit to apply an adhesive to said supporting sheet (200) in a pattern, for example the pattern of the rods (36), or the pattern of the areas between the rods (36). This may be done by spraying, or for example by selectively slot-coating; the apparatus (1) may thus comprise a slot-coater, for example with a coating pattern that corresponds to the rods (36), or the areas between the rods (36).
Any suitable adhesive can be used for this, for example so-called hotmelt adhesives used. For example. A sprayable hot melt adhesives, such as H.B. Fuller Co. (St. Paul, Minn.) Product No. HL-1620-B, can be used.
Alternatively, or in addition, it may be beneficial to apply a further immobilization adhesive to said absorbent structure produced by the apparatus (1) or method herein, e.g. to ensure the absorbent material (100) will stay substantially in the applied pattern. This immobilization adhesive may then for example be applied onto said absorbent layer just after application of said absorbent material (100) onto said supporting sheet (200).
The apparatus (1) herein may thus have a further immobilization adhesive application unit (50), e.g. downstream from said moving endless surface (30)′ meeting point. The method may have a corresponding method step. This is for example shown in FIG. 1.
This adhesive may be applied uniformly and/or homogeneously. This may be a thermoplastic adhesive material.
In accordance with certain embodiments, the thermoplastic adhesive material may comprise, in its entirety, a single thermoplastic polymer or a blend of thermoplastic polymers, having a softening point, as determined by the ASTM Method D-36-95 “Ring and Ball”, in the range between 50° C. and 300° C., or alternatively the thermoplastic adhesive material may be a hot melt adhesive comprising at least one thermoplastic polymer in combination with other thermoplastic diluents such as tackifying resins, plasticizers and additives such as antioxidants. In certain embodiments, the thermoplastic polymer has typically a molecular weight (Mw) of more than 10,000 and a glass transition temperature (Tg) usually below room temperature or −6° C.>Tg<16° C. In certain embodiments, typical concentrations of the polymer in a hot melt are in the range of about 20 to about 40% by weight. In certain embodiments, thermoplastic polymers may be water insensitive. Exemplary polymers are (styrenic) block copolymers including A-B-A triblock structures, A-B diblock structures and (A-B)n radial block copolymer structures wherein the A blocks are non-elastomeric polymer blocks, typically comprising polystyrene, and the B blocks are unsaturated conjugated diene or (partly) hydrogenated versions of such. The B block is typically isoprene, butadiene, ethylene/butylene (hydrogenated butadiene), ethylene/propylene (hydrogenated isoprene), and mixtures thereof. Other suitable thermoplastic polymers that may be employed are metallocene polyolefins, which are ethylene polymers prepared using single-site or metallocene catalysts. Therein, at least one comonomer can be polymerized with ethylene to make a copolymer, terpolymer or higher order polymer. Also applicable are amorphous polyolefins or amorphous polyalphaolefins (APAO) which are homopolymers, copolymers or terpolymers of C2 to C8 alpha olefins. In exemplary embodiments, the tackifying resin has typically a Mw below 5,000 and a Tg usually above room temperature, typical concentrations of the resin in a hot melt are in the range of about 30 to about 60%, and the plasticizer has a low Mw of typically less than 1,000 and a Tg below room temperature, with a typical concentration of about 0 to about 15%. In certain embodiments, the thermoplastic adhesive material is present in the form of fibers. In some embodiments, the fibers will have an average thickness of about 1 to about 50 micrometers or about 1 to about 35 micrometers and an average length of about 5 mm to about 50 mm or about 5 mm to about 30 mm.
Further Method Steps/Apparatus (1) Units
The apparatus (1) and method herein may comprise the further step/unit, of applying a further supporting sheet (300) onto said absorbent structure, to enclose said absorbent material (100), as know in the art. This is for example shown in FIG. 1.
The apparatus (1) and method herein may alternatively or in addition comprise the apparatus (1) unit/method step of folding the supporting sheet (200) over the absorbent material (100) to enclose it thereby.
It may comprise a sealing unit, sealing step to seal the two supporting sheet (200) or the folded supporting sheet (200) along the peripheral edges of the absorbent structure/layer. The absorbent structure may alternatively or in addition be combined with other layers, such as an acquisition layer, or topsheet and the apparatus (1) and method herein may comprise according steps/units.
The method or apparatus (1) herein may be to produce an absorbent core or structure that comprises two or more of the above described absorbent structures; for example two such layers, superposed on one another such that the absorbent material (100) of a first layer and the absorbent material (100) of the other second layer are adjacent one another and sandwiched between the supporting sheet (200) of the first layer and the supporting sheet (200) of the second layer. This is for example shown in FIG. 3.
The apparatus (1) herein may thus be a combination apparatus (1), comprising two or more, e.g. two, of the apparatuses (1) described herein, to produce two or more, e.g. two, absorbent structures, and then comprising a combining unit to combine the absorbent structures. The method may comprise according method step(s).
The strips where no absorbent material (100) of one layer is present may then be superposed on the strips where no absorbent material (100) is present of the other layer, to form joined strips; alternatively, they may be alternating, so that a strip where no absorbent material (100) of one layer is superposed onto the absorbent material (100) of the other layer.
In some embodiments, when the two layers are combined, the center (referring to the width) of a (or of each of) the absorbent material (100) strips of one layer overlays and contacts the center of a (or of the respective) strip where no absorbent material (100) is present of the other layer, and optionally vice versa. Hence, one or more, or each, absorbent material (100) strip of the one layer may be placed centrally on or in the strip without absorbent material (100) of the other layer and vice versa.
The absorbent structure produced with the method/apparatus (1) of the present disclosure herein may also be combined with an absorbent structure produced by a method/apparatus (1) other than of the present disclosure, said combination may be done as set out above.
In some embodiments, the apparatus (1) may comprise a pressure means, such as a pressure roll (70), that can apply pressure onto the absorbent structure, and typically on the supporting sheet thereof, and/or onto the further material if combined with the absorbent structure as described herein; or as for example shown in FIG. 3, on one of the supporting sheets (200; 300) sandwiched on either side of the absorbent layer or layers.
The pressure may be applied selectively onto said supporting sheet (200) or on any of the further material/layer that placed over the absorbent layer, as described above in this section.
This pressure application may optionally be done to selectively apply pressure only onto the strips of the supporting sheet (s) (200; 300) or further material that comprise (on the opposed surface) no absorbent material (100), to avoid compaction of said absorbent material (100) itself.
Thus, the apparatus (1) may comprise a pressure means (70) that has a raised pressuring pattern (71) corresponding to said rods (36), so that the raised pressure pattern (71) can mate with the strips of the supporting sheet (200) that have no absorbent material (100) (on its surface), that are or were supported by said rods (36). The method may have an according method step.
Absorbent Articles
The apparatus (1) and method of the present disclosure are for example useful to produce absorbent structures, or absorbent cores (absorbent structures combined with a further material, as described herein) suitable for absorbent articles.
Absorbent articles may include diapers, including fastenable diapers and (refastenable) training pants; adult incontinence undergarments (pads, diapers) feminine hygiene products (sanitary napkins, panty-liners), breast pads, care mats, bibs, wound dressing products, and the like. As
The absorbent article herein may comprise in addition to an absorbent structure or core produced by the method/apparatus (1) herein, a topsheet and backsheet, and for example one or more side flaps or cuffs. The topsheet or cuffs or side flaps may comprise a skin care composition or lotion or powder, known in the art, panels, including those described in U.S. Pat. Nos. 5,607,760; 5,609,587; 5,635,191; 5,643,588.
Preferred absorbent articles herein comprise a topsheet, facing the wearer in use, for example a nonwoven sheet, and/or an apertured sheet, including apertured formed films, as known in the art, and a backsheet.
The backsheet may be liquid impervious, as known in the art. In preferred embodiments, the liquid impervious backsheet comprises a thin plastic film such as a thermoplastic film having a thickness of about 0.01 mm to about 0.05 mm. Suitable backsheet materials comprise typically breathable material, which permit vapors to escape from the diaper while still preventing exudates from passing through the backsheet. Suitable backsheet films include those manufactured by Tredegar Industries Inc. of Terre Haute, Ind. and sold under the trade names X15306, X10962 and X10964.
The backsheet, or any portion thereof, may be elastically extendable in one or more directions. The backsheet may be attached or joined to a topsheet, the absorbent structure/core herein, or any other element of the diaper by any attachment means known in the art.
Diapers herein may comprise leg cuffs and/or barrier cuffs; the article then typically has a pair of opposing side flaps and/or leg and/or barrier cuffs, each of a pair being positioned adjacent one longitudinal side of the absorbent structure/core, and extending longitudinally along said absorbent structure/core, and typically being mirror images of one another in the longitudinal axis (which may be MD axis) of the article; if leg cuffs and barrier cuffs are present, then each leg cuffs is typically positioned outwardly from a barrier cuff. The cuffs may be extending longitudinally along at least 70% of the length of the article. The cuff(s) may have a free longitudinal edge that can be positioned out of the X-Y plane (longitudinal/transverse directions) of the article, i.e. in z-direction. The side flaps or cuffs of a pair may be mirror images of one another in the longitudinal axis of the article. The cuffs may comprise elastic material.
The diapers herein may comprise a waistband, or for example a front waistband and back waist band, which may comprise elastic material.
The diaper may comprise side panels, or so-called ear panels. The diaper may comprise fastening means, to fasten the front and back, e.g. the front and back waistband. Preferred fastening systems comprise fastening tabs and landing zones, wherein the fastening tabs are attached or joined to the back region of the diaper and the landing zones are part of the front region of the diaper.
The absorbent article may also include a sub-layer disposed between the topsheet and the absorbent structure/core, capable of accepting, and distributing and/or immobilizing bodily exudates. Suitable sublayers include acquisition layers, surge layers and or fecal material storage layers, as known in the art. Suitable materials for use as the sub-layer may include large cell open foams, macro-porous compression resistant non woven highlofts, large size particulate forms of open and closed cell foams (macro and/or microporous), highloft non-wovens, polyolefin, polystyrene, polyurethane foams or particles, structures comprising a multiplicity of vertically oriented, optionally looped, strands of fibers, or optionally apertured formed films, as described above with respect to the genital coversheet. (As used herein, the term “microporous” refers to materials that are capable of transporting fluids by capillary action, but having a mean pore size of more than 50 microns. The term “macroporous” refers to materials having pores too large to effect capillary transport of fluid, generally having pores greater than about 0.5 mm (mean) in diameter and more specifically, having pores greater than about 1.0 mm (mean) in diameter, but typically less than 10 mm or even less than 6 mm (mean).
All patents and patent applications (including any patents which issue thereon) assigned to the Procter & Gamble Company referred to herein are hereby incorporated by reference to the extent that it is consistent herewith.
The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”
All documents cited in the Detailed Description of the present disclosure are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present disclosure. To the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.
While particular embodiments of the present disclosure have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the present disclosure. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

## Claims

1. A method of making an absorbent structure having an absorbent layer and therein longitudinally extending strips that are free of absorbent material, the absorbent layer being supported on a supporting sheet, the method comprising the steps of:
providing a moving endless surface moving in a machine direction (MD) having an outer shell with a forming receptacle, having an average width and transverse direction and dimension, and having an average length and longitudinal dimension, the average length being more than the average width; the receptacle comprising a multitude of substantially longitudinally extending rods, spaced apart from one another in a transverse direction, each rod having a maximum transverse width dimension of at least 0.3 mm and each of the rods having a top portion and an opposing bottom portion, the bottom portion being adjacent an inner grid, and the minimum distance transversely between neighboring rods being at least 1 mm, and the rods each having an average height dimension perpendicular to the transverse and longitudinal dimensions of at least 1 mm; the moving endless surface being connected to one or more vacuum systems applying a vacuum suction to the receptacle;
receiving absorbent material on a second moving endless surface comprising longitudinally extending rows of cavities, wherein the rows of cavities are separated from each other by raised strips;
retaining the absorbent material in the cavities;
applying adhesive to the supporting sheet in substantially longitudinal stripes;
transporting the supporting sheet to the outer shell, onto the top portions of the rods;
pulling the supporting sheet having the longitudinal stripes of adhesive partially in between neighboring rods by the vacuum suction, to form undulations in the supporting sheet between the rods and to form crests on the upper portion of the rods;
depositing absorbent material onto the supporting sheet present on the forming receptacle;
mating the raised strips and the rods during transfer of the absorbent material to the supporting sheet;
pulling the absorbent material with the vacuum suction into the undulations of the supporting sheet and onto the longitudinal stripes of adhesive between neighboring rods to form absorbent strips;
removing absorbent material remaining on the crests of the supporting sheet;
applying adhesive to the absorbent strips and the supporting sheet between the absorbent strips to form a first absorbent structure; and
removing the first absorbent structure from the moving endless surface;
repeating the previous steps to form a second absorbent structure; and
combining the first absorbent structure and the second absorbent structure with a pressure roll having a raised pressure pattern by applying pressure with the raised pressure pattern to the first absorbent structure and the second absorbent structure where no absorbent material is present, such that the absorbent layers of both structures are sandwiched between the supporting sheet of the first structure and the supporting sheet of the second structure.

2. The method of claim 1, wherein the receptacle has a front edge zone and a back edge zone, each zone extending the respective transverse dimension of the receptacle, and wherein the front edge zone and back edge zone do not comprise the rods.

3. The method of claim 1, wherein the receptacle has a first average width dimension and the supporting sheet, or portion thereof that is on the receptacle, has a second average width dimension, and the ratio of the first to the second average width dimension is at least 1:1.2.

4. The method of claim 1, wherein the supporting sheet is a nonwoven sheet and the absorbent material is a particulate superabsorbent polymer material.

5. The method of claim 1, wherein the rods have a maximum width dimension which is at least 2 mm and the minimum distance transversely between neighboring rods being at least 3 mm.