MXPA99007966A - Stretchable absorbent structure for personal care products - Google Patents

Abstract

There is provided a stretchable absorbent material for personal care products which has a liquid permeable top sheet, a bottom sheet, and beams of an absorbent composition between the top and bottom sheets whereby the beams are spaced apart by bond rows therebetween. The stretchable absorbent material provides a more conformable product and can aid in moving liquid away from the target zone, and in air circulation within the product. Such an absorbent material may be used in personal care products like diapers, training pants, feminine hygiene products, absorbent underpants, adult incontinence products, and the like.

Description

ABSORBENT STRETCHABLE STRUCTURE FOR PERSONAL CARE PRODUCTS BACKGROUND OF THE INVENTION Absorbent systems for personal care products usually store essentially all liquid discharges in the crotch region and are not stretchable and have no retraction to the original shape. This results in the crotch region being heavily charged with the first insult and may result in insufficient capacity for a second, third or subsequent insult. This load of the crotch area can place the product s out of the user, causing a comfort for the user and creating the possibility of runoff. The lack of stretchability and retraction can cause lack of conformity to the body of the user and allow a runoff with the staining of the legs, bedding etc. resulting An absorbent which is stretched to conform to the body in spite of the movement of the wearer and which can help move the liquid out of the target area will be preferable to the storage design of the stretchable crotch area.

It is an object of this invention, therefore, to provide a stretchable absorber for personal care products. It is a further object of this invention to provide a stretchable absorbent which can provide a shape for the liquid to travel to areas away from the target area. Other important advantages for this stretchable absorbent system will be discussed later.

SYNTHESIS OF THE INVENTION The objects of this invention are achieved by an absorbent material which is stretchable and includes valleys which can direct the liquid in various directions. The absorbent material for the personal care products has a liquid-permeable upper sheet, a lower sheet and beams of an absorbent composition between the lower upper sheets whereby the beams are spaced apart by rows between them.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a drawing of a view of a stretchable absorbent showing an upper sheet, a lower leaf and beams of absorbent composition separated by area joined between the upper and lower sheets where the union in a single direction.

Figure 2 is a drawing of a view of a stretchable absorbent showing an upper sheet, a lower leaf and beams of absorbent composition separated by the united between the upper and lower sheets where the hiler is gathered together or "festooned" between the beams .

Figure 3 is a drawing of a view of a stretchable absorbent showing an upper sheet, a lower leaf and beams of absorbent composition separated by area joined between the upper and lower sheets wherein the upper leaf is provided with holes.

Figure 4 is a plan view of a stretchable absorber showing union in both machine direction (MD) and cross machine direction (CD) which provides CD and MD stretchability.

DEFINITIONS "Hydrophilic" describes fibers or surfaces of the fibers which are wetted by the aqueous liquids and contact with the fibers. The degree of wetting of the materials can, in turn, be described in terms of the contact angles and the surface tensions of the liquids and the materials involved. Equipment and techniques suitable for measuring the wettability of particular fiber materials or mixtures of fiber materials can be provided by a Cahn SFA-222 surface strength analyzer system, or an essentially equivalent system. When measured with this system, fibers having contact angles of less than 90 degrees are designated "wettable" hydrophilic, while fibers having contact angles equal to or greater than 90 degrees are designated "n humidifying" or hydrophobic.

The term "layer" when used in the singula may have the dual meaning of a single element of a plurality of elements.

The term "liquid" means a gaseous substance and / or a material that flows and can assume the internal form of a container into which it is poured or placed.

"Longitudinal" and "transverse" have their usual meanings. The longitudinal axis lies in the plan of the article and is generally parallel to a vertical plane which carries a user standing on the left-hand body halves when the item is used. The transverse axis lies in the plane of the article generally perpendicular to the longitudinal ej.

The "particles" refers to any geometric form such as, but is not limited to, flakes, beads, powders, spherical grains or the like.

As used herein, the term "knitted fabric or fabric" means a fabric having a fiber structure of individual yarns which are interleaved but not in an identifiable manner as in a woven fabric. Non-woven fabrics have been formed from many processes such as, for example, meltblowing processes, spinning processes, and carded and bonded weaving processes. The basis weight of the non-woven fabrics is usually expressed as ounces of material per square yard (osy) or grams per square meter (gsm) and useful fiber diameters are usually expressed in microns. (Note that to convert from ounces per square yard to grams per square meter, you must multiply ounces per square yard by 33.91).

As used herein the term "microfibers" means small diameter fibers having an average diameter of no more than about 75 microns, for example having an average diameter of from about 0.5 microns to about 50 microns, or more particularly, microfibers can have an average diameter of from about 2 miera to about 40 microns Another frequently used expression of fiber diameter is denier, which is defined as gram per 9,000 meters of a fiber and can be calculated as fiber diameter in square microns, multiply by the density e grams / cubic centimeter, multiplied by 0.00707. A lower denier indicates a finer fiber and a higher denier indicates a thicker or heavier fiber, for example, the diameter of a polypropylene fiber given as 15 You can convert to denier by putting the square, multiply the result by .89 g / cc and multiply by .00707. 15-micron leno has a denier d around 1.42 (152 x 0.89 x .00707 = 1.415). Outside the United States of America, the unit of measurement is most commonly the "tex" which was defined as grams per kilometer d fiber. The tex can be calculated as denier / 9.

The "yarn-bound fibers" refer to small diameter fibers which are formed by extruding the melted thermoplastic material as filaments d a plurality of usually circular and fine capillary vessels of a spinning organ with the diameter of the filaments extruded then being rapidly reduced as for example in the patent of the United States of America number 4,340,563 granted to Appel et al., and the patent of the United States of America number 3,692,618 granted to Dorschner and other patent of the United States of America No. 3,802.81 issued to Matsuki et al., United States of America patents number 3,338,992 and 3,341,394 granted to Kinney patents of the United States of America numbers 3,502.7 granted to Hartman and 3,542,615 granted to Dobo and others. Spunbonded fibers are not generally sticky when they are deposited on a collector surface. The yarn-bonded fibers are generally continuous and have average diameters (of a sample of at least 10) m large of 7 microns, more particularly of between about 20 microns.

The "melt blown fibers" means fibr formed by extruding a melt thermoplastic material through a plurality of usually circular and thin capillary vessels such as melted threads or filaments into usually warm and high velocity gas streams (eg air) which attenuate melted thermoplastic material filaments to reduce their diameter, which can be a microfiber diameter. Then, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form meltblown fiber fabric disbursed at random. The process is described, for example, in United States Patent No. 3,849,241. The melt blown fibers are microfibers which may be continuous discontinuous, are generally smaller than 10 microns average diameter, and are generally sticky when deposited on a collecting surface.

As used herein, the term "machine direction" or MD means the length of a fabric in the direction in which it is produced. The term "transverse direction to the machine" or CD means the width of the fabric, for example an address generally perpendicular to the machine direction.

As used herein, the term "coform" means a process in which at least one melt blown die head is arranged near a conduit through which other materials are added to the fabric while it is forming. Such other materials may be pulp superabsorbent particles, cellulose or short fibers, for example. The coform processes are shown in commonly assigned United States patents No. 4,818,464 to Lau and 4,100,324 issued to Anderson and others. The textiles produced by the coform process are generally referred to as coform materials.

"Conjugated fibers" refer to fibers which have been formed from at least two polymer sources extruded from separate extruders but spun together to form a fiber. Conjugated fibers are also sometimes referred to as multicomponent or bicomponent fibers. Polymers are usually different from one another even when the conjugated fibers can be monocomponent fibers. The polymers are arranged in different zones placed in essentially constant form across the cross section of the conjugate fibers and extend continuously along the length of the conjugate fibers. The configuration of such conjugated fibr can be, for example, a sheath / core arrangement where one polymer is surrounded by another or can be a side-by-side arrangement, a cake arrangement or an arrangement of "islands on the sea". . Conjugated fibers are taught, for example, in United States Patent No. 5,382.40 issued to Pike et al. For the two component fibers, the polymers may be present in proportions of 75/25, 50/50 25/75 or any other desired proportions. The fibers may also have shapes such as those described in US Pat. No. 5,277.97 to Hogle et al. Which describes fibers with conventional n forms.

The "biconstituent fibers" refer to fibers which have been formed from at least two extruded polymer from the same extruder as a mixture. The term "mixture" is defined below. The biconstituent fibers n have the various polymer components arranged in different zones placed relatively constant across the cross-sectional area of the fiber and the various polymers n are usually continuous along the entire length of the fiber, instead of this, usually setting protofibril fibrils which start and end at random. The biconstituent fibr is sometimes also mentioned as a multi-constituent fiber. Fibers of this generic type are discussed in, for example, U.S. Patent No. 5,108,827 issued to Gessner.

The "carded and bonded fabric" refers to fabrics that are made of short fibers which are sent through a combing or carding unit, which breaks and separates the short fibers in the machine direction to form a fabric. fibrous non-woven oriented in the direction of the machine generally. Such fibers are usually purchased in bales which are placed in a defibrator which separates the fibr before the carding unit. Once the tissue is formed this is then joined by one or more of several known uni methods. One such bonding method is the binding with powder where a powder adhesive is distributed through the fabric and then activated, usually by heating the fabric and the adhesive with hot air. Another suitable joining method is a pattern bond, wherein the heated calender rolls or the ultrasonic bonding equipment are used for one the fibers together, usually in a localized bonding pattern even when the fabric can be bonded across its surface. Complete if desired. Another suitable and known m joining method, particularly when bicomponent short fibers are used, is the bonding through air.

"Air placement" is a known process m by means of which a fibrous nonwoven layer can be formed. In the air laying process, bunches of small fibers having typical lengths vary from about 6 to about 19 millimeters (mm) and are separated and carried in an air supply and deposited on a forming grid, usually with the vacuum supply aid. The randomly deposited fibers are then bonded together using, for example, hot air or sprayed adhesive.

As used herein "ultrasonic bonding" means process carried out, for example by passing the tel between a sonic horn and an anvil roll as illustrated in U.S. Patent No. 4,374,888 issued to Bornslaeger.

As used herein the term "thermal dot attachment" involves passing a fabric or fiber fabric to be joined between a heated calender roll and an anvil roll. The calendering roll usually has, even if always, a pattern in some form so that the entire fabric is not bound through its entire surface, and the anvil roll is usually flat. As a result of this, various patterns have been developed for the calendered rolls for functional as well as aesthetic reasons. Typically, the area of bonding area varies from about 10% to about 30% of the area of the fabric laminated fabric. As is known in the art, point bonding keeps the laminate layer together as well as imparting integrity to each individual cap by joining the filaments and / or fibers within each. cap.

As used herein, bonding through air means a process of joining a fiber fabric in which the air which is hot enough to melt the polymers from which the fibers of the fabric are made is forced through the fabric. The air speed is between 100 and 50 feet per minute and the dwell time can be prolonged as 6 seconds. The melting and l resolidification of the polymer provides the bond.

As used herein, the terms "elastomeric" "elastomeric" when referring to a fiber, film or tel means a material which with the application of a pressing force is stretchable to a pressed and stretched length which is at least about 150 percent or one and a half times, its length not stretched and relaxed, and which recover at least 50 percent of its elongation with the release d the pressing and stretching force.

As used herein the term "recover" refers to a contraction of a stretched material upon the termination of a pressing force after stretching of the material by the application of the pressing force. For example, if a material that has an unpressed and relaxed length of an inch was 50 percent elongated by stretching it to a length of one and a half inches, the material would have a stretched length that is 150 percent of its relaxed length. If this example stretched material were to contract, that is to recover to a length of one and a tenth of an inch after the release of the pressing and stretching force, the material would have recovered 80 percent (0.4 inches) of s elongation.

"Personal care product" means diapers, underpants, absorbing undergarments, adult incontinence products, women's hygiene products.

DETAILED DESCRIPTION The objects of this invention are achieved by an absorbent system which is stretchable and includes valleys which can retain the liquid for absorption and direct the liquid in various directions. The stretchable absorbent material of this invention can carry out functions of emergence, distribution and containment in various degrees and the provision of these functions in only one material can result in material savings and manufacturing costs.

The stretchable absorbent materials of this invention include a top and bottom layer composed of material including films, non-woven fabrics, tissue or a combination thereof. The preferred materials for the top and bottom layers can be made by means of spinning, meltblowing and wet laying processes. The top layer refers to the layer towards the wearer and the bottom cap is the layer away from the top layer. user. The lower upper layers can be independently stretchable or elastic when none should be. The upper layer must be permeable to the liquid even though the lower layer does not need to be permeable so that if a film such as the top sheet is used it must be perforated, punctured or in some other way made permeable to the liquid.

Turning now to Figure 1, one can see a top sheet 1 and a bottom sheet 2 joined in spaced apart rows 3 which are "beams" 4 of an absorbent composition 5 in order to produce a stretchable absorbent 6 material. Discussion purposes it is assumed that beams 4 run in the direction of the machine, making the direction transversal to the machine perpendicular to the direction of the beams 4.

If the upper sheet and the lower sheet are not stretchable, stretchability can be provided to the absorbent material by compressing the absorbent composition in the joists when a stretching force is applied to the absorbent material in the cross machine direction. Recovery may also be provided depending on the recovery characteristics of the chosen absorbent composition. Alternatively, the absorbent material can be stretched by arranging it in such a way that the rows are folded together or festooned between the beams as shown in Figure 2. The beams 7 in Figure 2 are put closer together, making the material from which the rows 8 are made to fold. When a stretching force is applied in a direction perpendicular to the beams 7, the material in the rows 8 will be made "non-festooned" or less folded as to provide stretch to the absorbent material 9.

If the upper sheet and the lower sheet are stretchable, greater stretchability will be provided to the absorbent material since the tie rows will also be stretched. Lastly, if the upper sheet and the lower sheet are elastic, the stretchability will be provided, of course, but the properties of recovery will be quite strong as the elastic nature of the sheets pulling the absorbent material back to its original dimensions with the release of the stretching force. The recovery force can be regulated as desired by the selection of the type and amount of elastic used to produce the sheets and also by the choice of whether both sheets merely one sheet is elastic.

There may be an advantage in certain applications of having the lower sheet being permeable to liquid, such as, for example, in a diaper with the outer liquid-impervious cover. In this case, the liquid can penetrate the absorbent material and a part can be absorbed by the absorbent composition there, and an additional part of the liquid can continue through the absorbent material and exit the lower sheet. The liquid leaving the bottom sheet will be free to move within the diaper in the space between the bottom sheet and any underlying layers, will be contained by the impermeable outer cover, and will re-enter the absorbent material elsewhere, preferably where the The liquid loaded on the absorbent composition is not as large as the point at which the liquid left the lower sheet. In such form, the space between the absorbent material and the underlying layers, for example the outer cover, can satisfy the distribution function as desired in more advanced diaper designs. The distribution materials can be designed and provided to take advantage of a lower permeable sheet by absorbing the liquid exiting the lower sheet, moving the liquid, then releasing the liquid at the preferred locations.

The design of this invention provides a variety of benefits when incorporated into a personal care product such as a diaper. These benefits include shaping, fluid distribution, surface drying, BM handling (feces), ability to breathe or air circulation, and reduced wet volume which will be examined below in order.

The conformability of a product for personal care refers to the notch of the product on the user particularly when the user moves. A highly conformable product not only feels better for the user and that it does not tighten or pull, but reduces the possibility of product runoff. The stretchable elastic constructions of the invention help to provide a good degree of conformability to a personal care product within which they can be incorporated.

Clearly, the rows and beams in the absorbent material form valleys and peaks. The liquid can move through these valleys, can provide a distribution functionality, and can also be maintained, providing emergence functionality. The absorbent composition within the absorbent material absorbs the liquid and swells, and in doing so the valleys must become deeper and more pronounced, allowing an even greater flow of liquid. And additional increase of the liquid distribution can be achieved through the chemical treatment of the upper and / or lower leaves in the valleys with surfactants to increase the wettability. Inherently wettable fibers can also be used in valleys to increase wettability as well. The wettability of the valleys, particularly in the fibrous incorporations, will serve to increase the transmission along the valley floor and transfer the liquid to the regions far away from the target area. Since superabsorbents tend to fix the liquid at the discharge point, others have tried to remove the superabsorbent from the target area completely, even though this may increase the chance of runoff. The design of the present invention does not completely remove the superabsorbent from the target area but provides an opportunity to move some liquid insult along the valley floor before it is completely absorbed. Varying the amount or speed of absorption of the superabsorbent in the beams is yet another method for controlling the amount of liquid absorbed against the amount of liquid available for movement.

The distribution of liquid can also be improved by the physical arrangement of the rows and beams in, for example, a diaper. If the rows and beams run in a longitudinal direction, the movement of liquid towards the leg openings is impeded by the multiple peaks and valleys (in the additions provided herein) between the target area and the leg opening, with the peaks between each vall acting as a barrier or prey for the liquid.

It is highly desirable to maintain the surface of a close personal care product for user comfort and a saturated wet absorbent is a major source of surface moisture. The promotion of surface dryness can be achieved by the invention through geometry and chemical treatment. The geometric arrangement of the rows and beams is such that the valleys will not normally be in contact with the user's skin even when the absorbent material is placed directly against the skin, minimizing by the total area of contact of the skin. The treatment can be used to provide a top sheet that is hydrophobic non-wettable. A hydrophobic top sheet will not allow the liquid to remain on the peaks, thus maintaining the area in contact with the skin in a dry condition. A fully hydrophobic top sheet, however, will require some form of allowing the liquid to pass through it to the absorbent in the beams, such as perforations, openings, etc. as shown in Figure 3 which illustrates such hole 10. Alternatively, only a part of the top sheet, eg, the peaks, can be made hydrophobic (and optionally treat the valleys to make them hydrophilic). ) allowing so much that part of the upper sheet to remain permeable to liquid and yet maintain the peak area which is in contact with the skin in a dry state.

The valleys produced by the rows and beam can also function as fecal containment devices, for example to contain the user's solid exudates and prevent them from escaping from a personal care product, such as a diaper, in which incorporated the absorbent material. The space provided by the valley can greatly reduce the amount of feces that makes contact with the user. A chemical treatment of the upper leaf can also be used to improve the movement of faeces within the valleys by making the upper leaf more slippery or smooth, for example, using a silicone. In order for the valleys to function as fecal containment, of course, it will be required that no other layer, such as the lining, which would prevent the stool from reaching the absorbent material, will be placed between the absorbing material and the skin of the absorber. user. It is also desirable for fecal containment, that the valleys should be maintained after receiving feces. The maintenance of the valleys can be achieved by providing beams resistant to compression collapse by incorporating compression-resistant materials such as foams in the beams. The foams can be cut into small pieces and mixed with other beam contents during production.

The ability to breathe is a major goal in the development of personal care products because of concerns about rashes and the discomfort they may cause to the user. The valleys created by the beam and row design of the invention can function to improve air circulation or the ability to breathe within a personal care product and to help maintain the well-being of the skin. The geometry of the invention can provide an unimpeded and direct flow of air from the exterior of a personal care product through the valley regions. The air can also pass through the upper and lower sheets (when the lower sheet is not waterproof).

The rows of absorbent material can vary in size from about 2 millimeters to about 5 millimeters wide. The beams of the absorbent material can vary in size from about 5 millimeters to about 100 millimeters wide. A pattern such as that shown in United States Patent Application No. 08 / 622,493 for which payment rights have already been paid may also be used. The optimization of the row and beam sizes can be achieved to produce valleys that give the most desired properties for a given application.

In another aspect of this invention, it is also possible to choose joining strengths to create the rows, so that upon absorbing the absorbent composition the liquid swells, the joints break off and allow the absorbent composition to flow in and fill the space between the upper leaf and the lower leaf where the union had been. A bond strength lower than the breaking strength of either the top sheet or the bottom sheet can help ensure that no sheet breaks. If any leaves were to break this would allow the absorbent composition to escape into a personal care product containing the absorbent article 6, which is undesirable. In this design, the absorbent composition can be left to float freely, for example detached within the beams, so that it will be free to move within the open space by the separation of the row joints.

The traditional absorbent systems for personal care products can be generalized as having the functions of control of emergence and contention (retention) or SC. The absorbent material of this invention can be used in conjunction with the other functional materials and a personal care product. Other functional layers also include the distribution layers and, for example, the liners and the lower sheets.

The emergence control function is to quickly accept the incoming discharge and either absorb retain, channel or otherwise handle the liquid so that it does not run out of the article. An emergence layer may also be mentioned as a take-up layer, a transfer layer, a transport layer and the like is more typically interposed between and in an intimate liquid communication contact with the body-side lining another layer such as a retaining layer to which it may be subject.

A material that provides the emergence function should typically be capable of handling an incoming discharge of between about 60 and 100 cubic centimeters at a rate of about 5 to 20 cubic centimeters per second, for infants, for example. A sprouting control is typically provided by a fluff pulp in an absorbent product or by a high permeability nonwoven layer. For example, the sprouting layer may be a layer of woven cloth composed of a meltblown or bonded cloth. polyolefin filament spinning. Such woven fabric layers may include conjugated, biconstituent fibers and d homopolymers of short or other lengths and mixtures of such fibers with other types of fibers. The emergence layer may also be a carded and bonded fabric or a fabric placed by air composed of natural and / or synthetic fibers. The bonded and woven fabric can, for example, be a carded and bonded fabric, a carded and infrared-bonded fabric, or a carded and bonded fabric through air. The carded fabrics may optionally include a different fiber blend or blend and the fiber lengths within a selected fabric may range from about 3 millimeters to about 60 millimeters. An emergence material example can be found in the co-assigned United States of America patent application number 08 / 755,514 which presents an emergence material which is a wettable fiber fabric of at most 30 microns in diameter and where the tissue has a permeability of between about 25 and 1,500 darcis, a capillary tension of between 1.5 and 5 centimeters, and which maintains that permeability and tension of the capillary over the life of the tissue. It is preferred that the fabric has a density between about 0.02 grams per cubic centimeter to about 0.07 grams per cubic centimeter. Other example emergence material can be found in the patent application of the United States of America co-assigned series number 08 / 754,417. The traditional fibrous surgeries described above function to provide interstitial areas in which the liquid can be maintained.

An emergence layer can be used in conjunction with the absorbent material of this invention to retain and spread the liquid over a larger area of absorbent material. Such traditional emergence complements the absorbent material of the invention by providing more time for absorption by retaining a part of liquid insult in the gap of emergence before contact with the absorbent material of this invention. Under the pressure exerted by the user, the liquid in the interstice in the emergence layer can be released into the valleys of absorbent material for immediate retention distribution to other regions of the article.

The containment or retention function is to absorb the insult quickly and efficiently. A material that provides a retention function must be capable of pulling liquid from the distribution layer and absorbing the liquid if a significant "gel block" or a blockage of liquid penetration further into the absorbent by expanding the outer layers of the absorbent. Retention is often provided by the absorbent compositions such as those containing high-rate superabsorbent polymers such as the mixtures of superabsorbent d polyacrylate and lint. These materials absorb quickly retain the liquid. Examples of suitable superabsorbent include Favor 870 which is commercially available from Stockhausen Company of Greensboro, North Carolina 27406 and which is a crosslinked highly crosslinked superabsorbent, AFA 94-21-5 which is a suspension polymerized polyacrylate particle of 850 to 1,400 microns from Dow Chemical Company of Midland Michigan, 48674, and the plioacrylate gutter XL AFA-126-15, also from the Dow Chemical Company. Examples of fluff include pulp CR 1654 which is commercially available from Kimberly-Clark Corporation of Dallas Texas, and is a southern softwood pulp, pulp CR-2054, also from Kimberly-Clark Corporation, and the free pulp of High volume additive formaldehyde (HBAFF) which is available from Weyerhaeuser Corporation of Tacoma, WA, and which is a Southern softwood pulp fiber crosslinked with an increased wet modulus. The high volume additive formaldehyde-free pulp has a chemical treatment which settles in a curling and twisting, in addition to imparting aggregate dryness and wet stiffness and elasticity to the fiber. A binder may be present er. the containment material to mechanically stabilize the absorbent structure. An example binder is Danaklon a / s, located in Engdraget 22, KD-6800 Varde, Denmark, and is a conjugate of 2 deniers of conjugate sheath / polyethylene / polypropylene core (PE / PP) cut into stretches of 6 mm. Another exemplary binder is a liquid binder such as the Kymene® 557LX binder available from Hercules, Inc., of Wilmington Delaware. The superabsorbents can also be in the form of fibers and foams.

In addition to the control and containment functions of emergence in traditional absorbent systems, recent work has introduced another function which may be a separate cap interposed between layers S and C or may be incorporated into existing materials. This new function is a distribution function, producing a system with an emergence and contention control distribution or "SDC".

The distribution function is to move the fluid from the initial deposit point to where storage is desired. The distribution should probably take place at an acceptable speed so that the target area of insult, usually the crotch area, is ready for the next insult. The time between downloads and insults can vary from only a few minutes to hours, generally depending on the age of the user.

The materials from which the distribution layer can be made include woven fabrics and woven fabrics. For example, a distribution layer may be a layer of non-woven fabric composed of a melt blown or bonded fabric with polyolefin filament spinning. Such non-woven fabric layers may include conjugated, d-constituent and homopolymer fibers of short lengths or other mixtures of such fibers with other types of fibers. The distribution layer may also be a bonded and carded fabric, an air-laid cloth, or a wet-laid pulp structure composed of natural and / or synthetic fibers, or a combination thereof.

The absorbent products, for example diapers, generally also have a liner which goes against the wearer, a lower sheet which is the outermost layer, and may also contain other layers.

The lining is sometimes referred to as a forr sideways to the body or top sheet and is adjacent to the material d emergence. In the direction of the thickness of the article, the lining material is the layer against the user's skin in this way is the first layer in contact with the liquid, another exudate of the user. The lining also serves to isolate the user's skin from liquids maintained in the absorbent structure and must be docile, soft feeling and non-irritating.

Various materials can be used in the formation of the side-to-body liner of the present invention, including perforated plastic films, woven fabrics, non-woven fabrics, porous foams, similar cross-linked foams. Non-woven materials have been found to be particularly suitable for use in the formation of the side-to-body forr, including spin-bonded fabrics blown with polyolefin filament melting, or carded and bonded fabrics of natural polymers (e.g. d rayon or cotton) and / or synthetic polymer fibers (eg, polypropylene or polyester). For example, the side-to-body forr may be a non-woven fabric bonded with synthetic polypropylene filaments. The non-woven fabric may have a basis weight, for example, ranging from about 10.0 grams per square meter (gsm) to about 68.0 grams per square meter, and more particularly from about 14.0 grams per square meter to about 42.0 grams per square meter, a volume or thickness varying from about 0.13 millimeters (mm) to about 1.0 millimeters, and more particularly from about 0.18 millimeters around 0.55 millimeters, and a density of between about 0.025 grams per millimeter. cubic centimeter (g / cc) and around d 0.12 g / cc, and more particularly between about 0.068 g / c and about 0.083 g / cc. Additionally, the permeability of such nonwoven fabric can be from about 150 darcis to about 5,000 darcis. The non-woven fabric can be treated on the surface with a selected amount of surfactant, such as about 0.28% Triton X-102 surfactant, processed in another manner to impart the desired level of wettability and hydrophilicity. If a surfactant is used, it may be an internal additive or applied to the fabric by any conventional means, such as spraying, printing, embedding, brush coating and the like.

The lower sheet is sometimes referred to as the outer cover and is the layer furthest away from the user. The outer cover is typically formed of a thin thermoplastic film, such as a polyethylene film, which is essentially impermeable to liquid. The functions of the outer cover to prevent the exudates of the body contained in an absorbent structure from wetting or soiling the user's clothes, bedding or other materials that make contact with the diaper. The outer cover can be, for example, a polyethylene film having a thickness starting from about 0.5 mils (0.12 millimeters to about 5.0 mils). etched and / or matt finished to provide a more aesthetically pleasing appearance Other alternate constructions for the outer shell include woven or non-woven fibrous fabrics which have been constructed or treated to impart the desired level of liquid impermeability, or laminates formed from a woven or non-woven fabric and thermoplastic film The outer cover can optionally be composed of a microporous vapor or gas-permeable "breathability" material that is permeable to vapors or gas or that is essentially impermeable to liquid. Breathing ability can be imparted to polymer films by means of, for example the use of Developers in the film polymer formula extrude the filler formula into the film formula, extruding the filler / polymer formula into a film and then stretching the film enough to create voids around the filler particles, making it so much to the movie with a capacity to breathe. Generally, the more filler is used and the higher the degree of stretching, the greater the degree of ability to breathe. Some additions of the backrests can also serve the functions of a member that matches for the mechanical fasteners.

As previously noted, the top sheet and the bottom sheet can be made of various materials including non-woven fabrics, films, tissues and combinations thereof. Fabrics and films can be made through conventional means of various thermoplastic polymers. For example, polyolefins such as Dow Chemical ASPUN® 6811A linear low density polyethylene, and high density polyethylene 2553 LLDPE and 25355 and 12350 are suitable polymers. The polyethylenes have the melt flow rates, respectively, of about 26, 40, 25 and 12. Suitable polypropylenes include Escorene® P 3445 polypropylene from Exxon Chemical Company and PF-304 from Montell Chemica Company. Many other polyolefins are commercially available.

Elastomeric thermoplastic polymers useful in the practice of this invention can be those made from block copolymers such as polyurethanes, copolyether esters, polyether polyamide block copolymers, ethylene vinyl acetates (EVA), block copolymers having the ABA 'formula. or AB as copoly (styrene / ethylene-butylene), styrene poly (ethylene-propylene) -styrene, styrene-poly (ethylene butylene) -styrene, (polystyrene / poly (ethylene butylene) / polystyrene, poly (styrene / ethylene-butylene) / styrene) and the like.

Useful elastomeric resins include block copolymers having the general formula ABA 'or AB, wherein A and A' are each a thermoplastic polymer end block which contains a styrenic moiety, such as poly (vinyl arene) and where B is a middle block of elastomeric polymer such as a conjugated diene or a lower alken polymer. Block copolymers of type A-B-A 'may have different or equal thermoplastic block polymers for blocks A and A', and the block copolymers present are intended to encompass linear block copolymers, branched radial. In this regard, the radial block copolymers can be designated (A-B) m-X, wherein X is a polyfunctional atom molecule and in which each (A-B) is X-branched in a manner that A is an end block. In the radial blog copolymer, X may be a polyfunctional organic or inorganic molecule or atom and m is an integer having the same value as the functional group originally present in X. This is usually at least 3, and is frequently 4 or 5, but it's not limited to this. Therefore, in the present invention, the expression "block copolymer", and particularly block copolymer "AB-A '" and "AB", is intended to encompass all d-block copolymers having rubberized blocks and thermoplastic blocks as discussed above, which can be extruded (for example by meltblowing) and without limitation as to the number of blocks. The elastomeric nonwoven fabric can be formed of, for example, elastomeric block copolymers (polystyrene / poly (ethylene / butylene) / polystyrene). Commercial examples of such elastomeric copolymers are, for example, those known as KRATON® materials which are available from the Shell Chemical Company of Houston Texas. KRATON® block copolymers are available in several different formulas, and some of which are identified in U.S. Patent Nos. 4,663,220, 4,323,534, 4,834,738, 5,093,422 and 5,304,599, incorporated herein by reference each in its entirety.

Polymers composed of an elastomeric tetrablock copolymer d A-B-A-B can also be used in the practice of this invention. Such polymers are discussed in U.S. Patent No. 5,332,61 issued to Taylor et al. In such polymers, A is a thermoplastic polymer block and B is a hydrogenated isoprene monomer unit to essentially one poly (ethylene-propylene) monomer unit. An example of such a tetrablock copolymer is an elastomeric block copolymer of styrene poly (ethylene-propylene) -styrene-poly (ethylene-propylene) or SEPSE available from Shell Chemical Company of Houston Texas under the trade designation KRATON® G-1657 .

Other exemplary elastomeric materials which may be used include polyurethane elastomeric materials such as, for example, those available under the trademark ESTAÑE® of B. F. Goodrich & Company or MORTHANE® of Morto Thiokol Corporation, elastomeric polyester materials such as, for example, those available under the trade designation HYTREL® of E. I. DuPont De Nemours & Company, those known as ARNITEL®, formerly available from Akzo Plastics of Arnhem, The Netherlands and now available from DSM d Sittard, The Netherlands.

Another suitable material is a polyester block amid copolymer having the formula: O O I I I I I I I HO- [--C - PA- PE - 0-] n - H wherein n is a positive integer, PA represents a polyamide polymer segment and PE represents a segment d polymer polyether. In particular, the polyamide block amide copolymer has a melting point of from about 150 degrees centigrade to about 170 degrees centigrade, as measured in accordance with ASTM D-789; a Melt Index of from about 6 grams per 10 minutes to about 2 grams per 10 minutes, as measured in accordance with ASTM D-1238 Q (load of 235 c / l kilogram); a flexural modulus d of from about 20 MPa to about 200 MPa, as measured in accordance with ASTM D-790; a tensile strength at breaking from about 2 Mpa to about 33 Mpa as measured in accordance with ASTM D-63 and a final elongation at break from about 50 percent to about 700 percent as measured by ASTM D 638. A particular incorporation of the polyamide block amide copolymer has a melting point of about 15 degrees centigrade as measured in accordance with ASTM D-789; u Melt index of about 7 grams per 10 minutes, com was measured according to ASTM D-1238, condition Q (235 c / kg load); a flexural modulus of elasticity d around 29.50 MPa, as measured in accordance with ASTM D-790; a tensile strength at break of about 29 MPa, a measurement in accordance with ASTM D-639; and an elongation to break of about 650 percent as measured according to ASTM D-638. Such materials are available in various classes under the PEBAX® trade designation of EL Atochem Inc., of Glen Rock, New Jersey. Examples of the use of such polymers can be found in U.S. Patent Nos. 4,724,184, 4,820,572,923,742, incorporated herein by reference in their entirety, issued to Killian et al, and assigned to the same assignee of this invention. .

The elastomeric polymers also include the copolymers of ethylene and at least one vinyl monomer, such as, for example, vinyl acetates, unsaturated aliphatic monocarboxylic acids, and esters of such monocarboxylic acids. The elastomeric copolymers and the formation of the elastomeric non-woven fabrics thereof elastomeric copolymers are described in, for example, U.S. Patent No. 4,803,117.

The thermoplastic copolyester elastomers include the copolyester esters having the general formula: O O O O i i I I I I I H- ([0-G-0-C-C6H4-C] b- [O- (CH2) a-0-C-C6H4-Cl] 'm) n-0- (CH ^ -OH wherein "G" is selected from the group consisting of poly (oxyethylene-alpha, omega-diol, poly (oxypropylene-alpha, omega-diol, poly (oxytetramethylene) -alpha-omega-diol, and "a" and "b" or integers positive including 2, 4 and 6, "m" and "n" are positive integers including 1-20, such materials generally have an elongation at break from about 600 po to 750 percent when measured in accordance with ASTM 638 and a melting point of from about 350 ° F around 400 ° F (176 to 205 ° C) when measured according to ASTM D-2117.

Commercial examples of such copolyester materials are, for example, those known as ARNITEL® formerly available from Akzo Plastics of Amhem, The Netherlands now available from DSM of Sittard, The Netherlands, or that known as HYTREL® which are available from El duPont de Nemours of Wilmington, Delaware. The formation of an elastomeric non-woven fabric of polyester elastomeric materials is discussed in, for example, U.S. Patent No. 4,741,949 issued to Morman et al. And in U.S. Patent No. 4,707, 39 granted to Boggs, incorporated herein by reference.

Suitable elastomeric polymers also include a relatively new class of polymers, which have excellent barredability, breathability and elasticity. The new class of polymers have a narrow polydispersity number d, for example: Mw / Mn is 4 or less can be produced according to the metallocene process.

The metallocene process generally uses the catalyst which is activated, for example, ionized by a co-catalyst. An exhaustive list of such compounds is included in U.S. Patent No. 5,374,696 issued to Rosen et al. And assigned to Dow Chemical Company. Such compounds are also discussed in U.S. Patent No. 5,064,802 issued to Steven et al., And also assigned to Dow.

The metallocene process is the subject of a number of patents, for example, U.S. Patents Nos. 4,542,199 to Kaminsky et al., 5,189.19 to LaPointe et al., 5,352,749 to Exxon Chemica Patents, Inc. ., 5,278,272 and 5,272,236 granted to Lai and other 5,204429 and 5,349,100.

The polymers produced using the metallocene catalysts have the unique advantage of having a very narrow molecular weight range. The polydispersity numbers (Mw / Mn) d below 4 and still as low as 2 are possible for the polymer produced from metallocene. These polymers also have a controlled short chain branching distribution when compared to similarly similar polymers produced by the Ziegler-Natta type.

It is also possible to use a metallocene catalyzed system to control the isotacticity of the mu polymer closely when selective metallocene stereo catalysts are employed. In fact, the polymers have been produced having an isotacticity in excess of 99 percent. It is also possible to produce a highly syndiotactic polypropylene using the system.

The control of the isotacticity of a polymer can also result in the production of a polymer containing four blocks of isotactic material and blocks of atactic material alternating over the length of the polymer chain. This construction results in an elastic polymer by virtue of the part atactic Such polymer synthesis is discussed in the journal Science, volume 267 (January 13, 1995) on page 191 in an article by K.B. Wagner Wagner, discussing the work of Coates and Waymounth, explains that the catalyst oscillates between the stereochemical forms resulting in a polymer chain having current lengths of stereo isotactic centers connected to current lengths of atactic centers. E isotactic domain is reduced producing elasticity. Geoffre W. Coates and Robert M. Waymounth, in an article entitled "Oscillating Stereocontrol: A strategy for the synthesis of thermoplastic elastomeric polypropylene" on page 217 in the same issue, discusses their work in which they use bis (2-dichloride) penilidenil) - metallocene zirconium in the presence of methyl aluminoxane (MAO) and, by varying the pressure in the reactor temperature, oscillate the polymer of isotactic and atactic entr.

Metallocene polymers are available from Exxon Chemical Company, under the trademark ACHIEVE® for polymers based on polypropylene and EXACT® and EXCEED® for polymers based on polyethylene. The Dow Chemical Company of Midland, Michigan has commercially available polymers under the name ENGAGE®. These materials are believed to be produced using selective non-stereo melocene catalysts. Exxon s generally refers to its metallocen catalyst technology as "single site" catalysts, while Dow s refers to theirs as catalysts "of constrained geometry under the name INSIGHT® to distinguish them from the traditional Ziegler-Natta catalysts, which they have multiple reaction sites In the practice of the present invention, elastic polyolefins such as polypropylene and polyethylene are preferred, more especially elastic polypropylene.

Other suitable polymers for the film and / or nonwoven layers are commercially available under the trade designation "Catalloy" from Montell Chemical Compan of Wilmington, Delaware and polypropylene. The specific commercial examples are Catalloy KS-084P and Catalloy KS-057P. The Catalloy polymers are discussed in the European patent application EP 0444671 A3 based on the application number 91103014.6), European patent application EP0472946A2 (based on the application No. 91112955.9), European patent application EP 0400333 A2 (based on the application No. 90108051.5) U.S. Patent No. 5,302,454 and U.S. Patent No. 5,368,927.

The processing aids can be added to the elastomeric polymer as well. A polyolefin, for example, can be mixed with an elastomeric polymer (e.g., the elastomeric block copolymer) to improve the processability of the composition. The polyolefin must be one which, when mixed, is subjected to an appropriate combination of high pressure and high temperature conditions, and extrudable in a mixed form with the elastomeric polymer. Useful blending polyolefin materials include, for example, polyethylene, polypropylene and polybutene including copolymers of ethylene, copolymers of propylene copolymers of butene. A particularly useful polyethylene can be obtained from U.S. I. Chemical Company under the trade designation Petrothene NA 601 also mentioned herein as PE NA 60 or polyethylene NA 601). Two or more of the polyolefins may be used. The extrudable mixtures of the elastomeric polymers and polyolefins are described in, for example, U.S. Patent No. 4,663,220.

The absorbent materials of this invention may also have topical treatments applied to these for more specialized functions. Such topical treatments and their methods of application are known in the art and include, for example, alcohol repellency treatments, antistatic treatment and the like, applied by spraying, embedding, etc. An example of such a topical treatment is the Zelec® antistatic application, available from E.l. duPont, Wilmington, Delaware.

The building materials for the absorbent composition of the stretchable absorbent material of this invention have been previously discussed. The absorbent composition may include 20 to 100 percent by weight of the superabsorbent, d from 80 to 0 percent by weight of pulp and optionally d from a positive amount to about 10 percent by weight of a binder. The absorbent composition can be made according to known processes, such as by the cofor process and can incorporate foam to increase the compression strength as discussed above.

The stretchable absorbent material of this invention can be made, for example, by depositing a film and / or a nonwoven on a mobile conveyor belt or "forming wire" by depositing the desired absorbent composition in rows on the film and / or the non-woven fabric. fabric, depositing a second layer of film and / or nonwoven on the absorbent composition, then joining the layers together in rows between the absorbent composition. The bond can be achieved by means known in the art such as thermally, chemically. ultrasonically, etc. Alternatively, the stretchable absorbent material can be made by providing a film and / or a previously produced nonwoven fabric, depositing the absorbent composition in swaths, and then depositing a freshly formed film and / or nonwoven layer providing a previously produced layer, and then join the layers together. In any case, the absorbent composition can be deposited in rows in the direction transverse to the machine or in the machine direction, depending on the desired direction of stretching, since, as previously taught, the material will be stretched in a perpendicular direction. to the direction of the rows and beams.

Still another method for making the absorbent material of this invention is to provide a carded fabric and short fiber fabric, place multiple threads of fibrous superabsorbent tow on the carded fabric and attached to provide a second carded fabric and bonded on the upper part of the fabric. tow and the first carded and bonded fabric and ultrasonically joined the two carded fabrics and joined together and rows spaced apart between the fibrous superabsorbent tow. Such incorporation was produced using 146 grams per square meter of a known fibrous superabsorbent with Fibersorb®, which is a 100 percent fibrous superabsorbent per scientifically available from Arco Chemical Company, of Newto Square, Pennsylvania, between two layers of 50 grams per square meter through a carded fabric material bonded through air, made from 60 percent by weight of 3 denier bicomponent agglutinant fibers from BASF Corporation of Enka, Carolina of the North, and 40 percent by weight of 6 denier polyester (PET) fiber from Hoescht Celanese of Charlotte, North Carolina. Fibrous superabsorbents are also available as Oasis® superabsorbent from Technical Absorbent of Grimsby, UK, and Fiberdi® superabsorbents from Camelo Superabsorbents, Inc., of Charlotte, North Carolina.

In yet another embodiment, the absorbent composition may be a blend of melt blown elastomeric fibers, optionally treated for wettability and superabsorbent. The meltblown fibers provide liquid storage space in the interstice areas and also act as a binder for the superabsorbent particles. The meltblown fibers can be present in an amount of up to 50 percent by weight.

Another embodiment produced by the inventors used elastic Lycra® yarns laminated between two layers of 20 grams per square meter of polypropylene fabric spun by the upper and lower layers. The LYCRA® yarns were spaced by about 5 millimeters and were attached to two layers joined with yarn using a hot-melt adhesive. The thermal bond was used to produce the absorbent material by bonding the two layers of the LYCRA® / spinning / spinning laminate together with yarn widths of about 4 millimeters spaced by about 35 millimeters using a spinning machine. Vertro thermal impulse heat seal (model 20P) from Vertrod Corporation of Toccoa, Georgia. The heat sealer had a residence time of 1.5 and a heat value of 2.5 on a scale of 1-10. The laminate with thread and Lycra® yarn was stretched 160 percent and recovered 100 percent. An absorbent composition was placed between the rows before bonding and comprised about 37 percent by weight of Favor® 870 superabsorbent and about 63 percent by weight of CR-1654 fluff pulp. The absorbent material thus produced had a basis weight of about 55 grams per square meter.

In another embodiment, an elastic film (code X-MAX 264.0) from CT Films Corporation was used as the top and bottom layers. This film is stretched in both MD and CD directions. The joints were around 3 millimeters wide and the unbonded area was around 5 millimeters wide. The superabsorbent used was a composite having a width of about 30 millimeters which was not attached to any the upper or lower layerFor example, it was contained or floated in a bag between the joints. As a result of this, the absorbent material was able to stretch in a direction parallel with the beams, not just perpendicular to it, even though the joining rows were parallel to the beams. Therefore, this material had both stretching properties in the transverse direction to the machine and in the direction of the machine when the stretching force was applied to the upper and lower sheets. It is interesting to note that in this incorporation, even when the bond row was only about 3 millimeters wide, the distance between the superabsorbent beams was essentially greater since much of the pocket between the rows remained empty by virtue of the difference between the absorbent width (30 millimeters) and the distance between the joints (50 millimeters).In another way of producing a stretchable absorbent material which is stretched in both the machine direction and the cross machine direction, the absorbent composition must be deposited in a discontinuous manner so that the joints 11 can be provided in both the directions of the machine and the cross machine direction as shown in Figure 4.

The stretchable absorbent material of this invention can be incorporated into a personal care product such as a diaper with the rows and beams running longitudinally or transversely, depending on the desired movement of the liquid. The longitudinal direction is preferred in a diaper since it is usually desired to move the liquid out of the target area to the front or rear end.

As can be seen from the description given above, s provides here an absorbent article wherein some of the discharge can move outward from the target area and e where the absorbent is stretchable. A great advance is provided in the absorbent technology and in the design of a product for personal care.

Although only a few embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications to exemplary embodiments are possible without departing materially from the novel teachings and the advantages of this invention. Therefore, all those modifications are intended to be included within the scope of this invention as defined in the following clauses. In the claims, the media clauses plus function are intended to cover the structures described herein as carrying out the recited function and not only the structural equivalents without also the equivalent structures. Therefore even when a nail and a screw may not be structural equivalents in the sense that a nail employs a cylindrical surface to secure wooden parts together, while a screw employs a helical surface in the environment of the fastening of part of wood , a bald and a screw can be equivalent structure

Claims (17)

R E I V I N D I C A C I O N S

1. A stretchable absorbent material for personal care products comprising a liquid-permeable upper sheet, a lower sheet, and beams of an absorbent composition between said upper and lower sheets so that said beams are spaced apart and spaced by the tie between the same.

2. The stretchable absorbent material such and com is claimed in clause 1 characterized in that the lower leaf is permeable to liquid.

3. The stretchable absorbent material such and com is claimed in clause 1 characterized in that said lower leaf is impermeable to liquid.

4. The stretchable absorbent material such and com is claimed in clause 1 characterized in that the absorbent composition comprises a mixture of superabsorbent particles and wood pulp fluff.

5. The stretchable absorbent material such and com is claimed in clause 1 characterized in that the swaths are between about 2 and about 50 millimeters and said beams are between about 5 and 100 millimeters wide.

6. The stretchable absorbent material such and com is claimed in clause 1 characterized in that it has a superabsorbent selected from the group consisting of fibers, particles, foams and combinations thereof.

7. The stretchable absorbent material such and com is claimed in clause 1 characterized in that the air flows through said material in the valleys.

8. A person care product selected from the group consisting of diapers, training pants, absorbent undergarments, products for adult incontinence and products for women's hygiene comprising the material as claimed in clause 1.

9. The product as claimed in clause 8 characterized in that said product for personal care is a product for the hygiene of women.

10. The product as claimed in clause 8 characterized in that said product for personal care is a product for adult incontinence.

11. The product as claimed in clause 8 characterized in that said product for personal care is a diaper,

12. A diaper comprising a side-to-body liner in fluid communication with an emergence layer which is in fluid communication with the stretchable absorbent material as claimed in clause 1, characterized in that said absorbent material moves the liquid toward outside the target area through longitudinal valleys produced by said rows and beams.

13. The diaper as claimed in clause 8 characterized in that said absorbent composition comprises up to about 100 percent by weight of superabsorbent, from 80 to 0 percent by weight of pulp, up to about 10 percent by weight of a binder component and which has a density between about 0.1 and 0.4 g / cc.

14. An absorbent material for personal care products comprising a liquid pervious top sheet, a bottom sheet, and absorbent beams therebetween, said beams being capable of being brought together to form a festooned configuration with the folds between said beams.

15. The absorbent material as claimed in clause 14 characterized in that said festooned configuration can be unstretched by e stretching said material in a direction perpendicular to the direction of the folds.

16. An absorbent material as claimed in clause 14 characterized in that it has a superabsorbent selected from the group consisting of fibers, particles, foams and combinations thereof.

17. An absorbent material as claimed in clause 14 characterized in that the air flows through said material in the valleys. E U M N A stretchable absorbent material is provided for personal care products which has a liquid-permeable top sheet, a lower sheet and beams of an absorbent composition between the upper and lower sheets whereby the beams are separated and spaced by tie rows between them. The stretchable absorbent material provides a more conformable product and can help to move the liquid out of the target zone, and to the air circulation within the product. Such absorbent material can be used in personal care products such as diapers, training underpants, women's hygiene products, absorbent undergarments, adult incontinence products, and the like.