Patent Application
20160235606
The present disclosure generally relates to an absorbent article, and more particularly to absorbent articles comprising absorbent particulate polymer material.
Absorbent articles, such as disposable diapers, training pants, and adult incontinence undergarments, absorb and contain body exudates. They are also 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 disposal 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 exudates, while maintaining or enhancing the absorbing and containing functions of the article.
Disposable absorbent articles, as disposable diapers, are often purchased and used in a relatively large volume. It has been desirable to make disposable absorbent articles with reduced bulk to reduce space needed for transportation, shelf display, and/or storage. Some absorbent articles, like disposable diapers, have been made thinner by using an absorbent polymer material (also known as super absorbent polymer), such as an absorbent particulate polymer material, as the primary liquid absorbent in the article. Absorbent particulate polymer material absorbs liquid and swells within the article.
A wearer may subject some absorbent articles, such as disposable diapers, to one or more rushes of liquid, such as when urinating. Such a wearer typically desires that the absorbent article absorb and hold all such liquid during initial and subsequent rushes of liquid. The rate of absorbency and capacity of the absorbent particulate polymer material may affect the absorbent article's ability to absorb and hold all liquid during initial and subsequent rushes of liquid. When an absorbent article is not able to absorb and hold all liquid, an undesirable liquid leak may occur.
Thus, there remains a desire to enhance the ability of some thin, flexible, and/or inexpensive absorbent articles to absorb and hold one or more rushes of liquid without substantial leakage of liquid from the absorbent article.
The present disclosure addresses one or more technical problems such as that described above. In some embodiments, the absorbent article may include: a lateral axis; a longitudinal axis; a front waist region on a first side of the lateral axis; a back waist region on a second side of the lateral axis; a first longitudinal side edge on a first side of the longitudinal axis; a second longitudinal side edge on a second side of the longitudinal axis: a first elastic leg feature proximate to the first longitudinal side edge; a second elastic leg feature proximate to the second longitudinal side edge; a topsheet; a backsheet; and an absorbent core positioned between the topsheet and the backsheet. The absorbent core may include a first area of absorbent particulate polymer material positioned at least partially between the longitudinal axis and the first longitudinal side edge, a second area of absorbent particulate polymer material positioned at least partially between the longitudinal axis and the second longitudinal side edge, and a third area of absorbent particulate polymer material. The first area of absorbent particulate polymer material may be convex relative to the longitudinal axis and concave relative to the first longitudinal side edge. The second area of absorbent particulate polymer material may be convex relative to the longitudinal axis and concave relative to the second longitudinal side edge. The third area of absorbent particulate polymer material may substantially surround the first area of absorbent particulate polymer material and the second area of absorbent particulate polymer material. Further, the first area of absorbent particulate polymer material has a first basis weight, the second area of absorbent particulate polymer material has a second basis weight, and the third area of absorbent particulate polymer material has a third basis weight. The third basis weight may be different than each of the first basis weight and the second basis weight.
In some embodiments, an absorbent article may include: a lateral axis; a longitudinal axis; a front waist region on a first side of the lateral axis; a back waist region on a second side of the lateral axis; a first longitudinal side edge on a first side of the longitudinal axis; a second longitudinal side edge on a second side of the longitudinal axis: a first elastic leg feature proximate to the first longitudinal side edge; a second elastic leg feature proximate to the second longitudinal side edge; a topsheet; a backsheet; and an absorbent core positioned between the topsheet and the backsheet. The absorbent core may include a first area of absorbent particulate polymer material, a second area of absorbent particulate polymer material, and a third area of absorbent particulate polymer material. The first area of absorbent particulate polymer material may be concave relative to the longitudinal axis. The second area of absorbent particulate polymer material may be concave relative to the longitudinal axis. The third area of absorbent particulate polymer material may substantially surround the first area of absorbent particulate polymer material and the second area of absorbent particulate polymer material. The first area of absorbent particulate polymer material has a first basis weight, the second area of absorbent particulate polymer material has a second basis weight, and the third area of absorbent particulate polymer material has a third basis weight. The first basis weight may be substantially the same as the second basis weight, and the third basis weight may be different than each of the first basis weight and the second basis weight.
In some embodiments, an absorbent article may include: a lateral axis; a longitudinal axis; a front waist region on a first side of the lateral axis; a back waist region on a second side of the lateral axis; a first longitudinal side edge on a first side of the longitudinal axis; a second longitudinal side edge on a second side of the longitudinal axis: a first elastic leg feature proximate to the first longitudinal side edge; a second elastic leg feature proximate to the second longitudinal side edge; a topsheet; a backsheet; and an absorbent core positioned between the topsheet and the backsheet. The absorbent core may include a first area of absorbent particulate polymer material, a second area of absorbent particulate polymer material, and a third area of absorbent particulate polymer material. The first area of absorbent particulate polymer material may extend in a direction substantially parallel with the longitudinal axis and may be disposed on a first side of the longitudinal axis. The second area of absorbent particulate polymer material may extend in a direction substantially parallel to the longitudinal axis and may be disposed on the second side of the longitudinal axis. The third area of absorbent particulate polymer material may substantially surround each of the first area of absorbent particulate polymer material and the second area of absorbent particulate polymer material. The first area of absorbent particulate polymer material has a first basis weight, the second area of absorbent particulate polymer material has a second basis weight, and the third area of absorbent particulate polymer material has a third basis weight. The third basis weight may be different than each of the first basis weight and the second basis weight.
Other features and advantages of the disclosure may be apparent from the following detailed description, drawings, and claims.
As summarized above, this disclosure encompasses a disposable absorbent article comprising an absorbent core located in a chassis and comprising absorbent particulate polymer material having a basis weight that varies across the absorbent core. Embodiments of such disposable absorbent articles are described hereinbelow along with embodiments of apparatuses and methods for making disposable absorbent articles.
As used herein, the following terms have the following meanings:
“Absorbent article” refers to devices that absorb and contain 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 diapers, training pants, adult incontinence undergarments, feminine hygiene products, breast pads, care mats, bibs, wound dressing products, 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.
“Absorbent core” means a structure typically disposed between a topsheet and backsheet of an absorbent article for absorbing and containing liquid received by the absorbent article and may comprise one or more substrates, absorbent polymer material disposed on the one or more substrates, and a thermoplastic composition on the absorbent particulate polymer material and at least a portion of the one or more substrates for immobilizing the absorbent particulate polymer material on the one or more substrates. In a multilayer absorbent core, the absorbent core may also include a cover layer. The one or more substrates and the cover layer may comprise a nonwoven. Further, the absorbent core is substantially cellulose free. The absorbent core does not include an acquisition system, a topsheet, or a backsheet of the absorbent article. In a certain embodiment, the absorbent core would consist essentially of the one or more substrates, the absorbent polymer material, the thermoplastic composition, and optionally the cover layer.
“Absorbent polymer material,” “absorbent gelling material,” “AGM,” “superabsorbent,” and “superabsorbent material” are used herein interchangeably and refer to cross linked polymeric materials that can absorb at least 5 times their weight of an aqueous 0.9% saline solution as measured using the Centrifuge Retention Capacity test (Edana 441.2-01).
“Absorbent particulate polymer material” is used herein to refer to an absorbent polymer material which is in particulate form so as to be flowable in the dry state.
“Absorbent particulate polymer material area” as used herein refers to the area of the core wherein the first substrate 64 and second substrate 72 are separated by a multiplicity of superabsorbent particles. In
“Airfelt” is used herein to refer to comminuted wood pulp, which is a form of cellulosic fiber.
“Comprise,” “comprising,” and “comprises” are open ended terms, each specifies the presence of what follows, e.g., a component, but does not preclude the presence of other features, e.g., elements, steps, components known in the art, or disclosed herein.
“Consisting essentially of” is used herein to limit the scope of subject matter, such as that in a claim, to the specified materials or steps and those that do not materially affect the basic and novel characteristics of the subject matter.
“Disposable” is used in its ordinary sense to mean an article that is disposed or discarded after a limited number of usage events over varying lengths of time, for example, less than about 20 events, less than about 10 events, less than about 5 events, or less than about 2 events.
“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. As used herein, term “diaper” also includes “pants” which is defined below.
“Fiber” and “filament” are used interchangeably.
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).
“Pant” or “training pant”, as used herein, refer to disposable garments 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.
“Substantially cellulose free” is used herein to describe an article, such as an absorbent core, that contains less than 10% by weight cellulosic fibers, less than 5% cellulosic fibers, less than 1% cellulosic fibers, no cellulosic fibers, or no more than an immaterial amount of cellulosic fibers. An immaterial amount of cellulosic material would not materially affect the thinness, flexibility, or absorbency of an absorbent core.
“Substantially continuously distributed” as used herein indicates that within the absorbent particulate polymer material area, the first substrate 64 and second substrate 72 are separated by a multiplicity of superabsorbent particles. It is recognized that there may be minor incidental contact areas between the first substrate 64 and second substrate 72 within the absorbent particulate polymer material area. Incidental contact areas between the first substrate 64 and second substrate 72 may be intentional or unintentional (e.g. manufacturing artifacts) but do not form geometries such as pillows, pockets, tubes, quilted patterns and the like.
“Thermoplastic adhesive material” as used herein is understood to comprise a polymer composition from which fibers are formed and applied to the superabsorbent material with the intent to immobilize the superabsorbent material in both the dry and wet state. The thermoplastic adhesive material of the present invention forms a fibrous network over the superabsorbent material.
“Thickness” and “caliper” are used herein interchangeably.
The chassis 12 of the diaper 10 in
The leg cuffs 24 and the elastic waist feature 26 may each typically comprise elastic members 28. One end portion of the diaper 10 may be configured as a first waist of the diaper 10. An opposite end portion of the diaper 10 may be configured as a second waist region 32 of the diaper 10. An intermediate portion of the diaper 10 may be configured as a crotch region 34, which extends longitudinally between the first and second waist regions 30 and 32. The waist regions 30 and 32 may include elastic elements such that they gather about the waist of the wearer to provide improved fit and containment (elastic waist feature 26). The crotch region 34 is that portion of the diaper 10 which, when the diaper 10 is worn, is generally positioned between the wearer's legs.
The diaper 10 is depicted in
The diaper 10 may also include such other features as are known in the art including front and rear ear panels, waist cap features, elastics and the like to provide better fit, containment and aesthetic characteristics. Such additional features are well known in the art and are e.g., described in U.S. Pat. No. 3,860,003 and U.S. Pat. No. 5,151,092.
In order to keep the diaper 10 in place about the wearer, at least a portion of the first waist region 30 may be attached by the fastening member 46 to at least a portion of the second waist region 32 to form leg opening(s) and an article waist. When fastened, the fastening system carries a tensile load around the article waist. The fastening system may allow an article user to hold one element of the fastening system, such as the fastening member 46, and connect the first waist region 30 to the second waist region 32 in at least two places. This may be achieved through manipulation of bond strengths between the fastening device elements.
According to certain embodiments, the diaper 10 may be provided with a re-closable fastening system or may alternatively be provided in the form of a pant-type diaper. When the absorbent article is a diaper, it may comprise a re-closable fastening system joined to the chassis for securing the diaper to a wearer. When the absorbent article is a pant-type diaper, the article may comprise at least two side panels joined to the chassis and to each other to form a pant. The fastening system and any component thereof may include any material suitable for such a use, including but not limited to plastics, films, foams, nonwoven, woven, paper, laminates, fiber reinforced plastics and the like, or combinations thereof. In certain embodiments, the materials making up the fastening device may be flexible. The flexibility may allow the fastening system to conform to the shape of the body and thus, reduce the likelihood that the fastening system will irritate or injure the wearer's skin.
For unitary absorbent articles, the chassis 12 and absorbent core 14 may form the main structure of the diaper 10 with other features added to form the composite diaper structure. While the topsheet 18, the backsheet 20, and the absorbent core 14 may be assembled in a variety of well-known configurations, preferred diaper configurations are described generally in U.S. Pat. No. 5,554,145 entitled “Absorbent Article With Multiple Zone Structural Elastic-Like Film Web Extensible Waist Feature” issued to Roe et al. on Sep. 10, 1996; U.S. Pat. No. 5,569,234 entitled “Disposable Pull-On Pant” issued to Buell et al. on Oct. 29, 1996; and U.S. Pat. No. 6,004,306 entitled “Absorbent Article With Multi-Directional Extensible Side Panels” issued to Robles et al. on Dec. 21, 1999.
The topsheet 18 in
The backsheet 26 may be joined with the topsheet 18. The backsheet 20 may prevent the exudates absorbed by the absorbent core 14 and contained within the diaper 10 from soiling other external articles that may contact the diaper 10, such as bed sheets and undergarments. In certain embodiments, the backsheet 26 may be substantially impervious to liquids (e.g., urine) and comprise a laminate of a nonwoven and a thin plastic film such as a thermoplastic film having a thickness of about 0.012 mm (0.5 mil) to about 0.051 mm (2.0 mils). Suitable backsheet films include those manufactured by Tredegar Industries Inc. of Terre Haute, Ind. and sold under the trade names X15306, X10962, and X10964. Other suitable backsheet materials may include breathable materials that permit vapors to escape from the diaper 10 while still preventing liquid exudates from passing through the backsheet 10. Exemplary breathable materials may include materials such as woven webs, nonwoven webs, composite materials such as film-coated nonwoven webs, and microporous films such as manufactured by Mitsui Toatsu Co., of Japan under the designation ESPOIR NO and by EXXON Chemical Co., of Bay City, Tex., under the designation EXXAIRE. Suitable breathable composite materials comprising polymer blends are available from Clopay Corporation, Cincinnati, Ohio under the name HYTREL blend P18-3097. Such breathable composite materials are described in greater detail in PCT Application No. WO 95/16746, published on Jun. 22, 1995 in the name of E. I. DuPont. Other breathable backsheets including nonwoven webs and apertured formed films are described in U.S. Pat. No. 5,571,096 issued to Dobrin et al. on Nov. 5, 1996.
In certain embodiments, the backsheet of the present invention may have a water vapor transmission rate (WVTR) of greater than about 2000 g/24 h/m2, greater than about 3000 g/24 h/m2, greater than about 5000 g/24 h/m2, greater than about 6000 g/24 h/m2, greater than about 7000 g/24 h/m2, greater than about 8000 g/24 h/m2, greater than about 9000 g/24 h/m2, greater than about 10000 g/24 h/m2, greater than about 11000 g/24 h/m2, greater than about 12000 g/24 h/m2, greater than about 15000 g/24 h/m2, measured according to WSP 70.5 (08) at 37.8° C. and 60% Relative Humidity.
In a certain embodiment, the acquisition system 50 may comprise chemically cross-linked cellulosic fibers. Such cross-linked cellulosic fibers may have desirable absorbency properties. Exemplary chemically cross-linked cellulosic fibers are disclosed in U.S. Pat. No. 5,137,537. In certain embodiments, the chemically cross-linked cellulosic fibers are cross-linked with between about 0.5 mole % and about 10.0 mole % of a C2 to C9 polycarboxylic cross-linking agent or between about 1.5 mole % and about 6.0 mole % of a C2 to C9 polycarboxylic cross-linking agent based on glucose unit. Citric acid is an exemplary cross-linking agent. In other embodiments, polyacrylic acids may be used. Further, according to certain embodiments, the cross-linked cellulosic fibers have a water retention value of about 25 to about 60, or about 28 to about 50, or about 30 to about 45. A method for determining water retention value is disclosed in U.S. Pat. No. 5,137,537. According to certain embodiments, the cross-linked cellulosic fibers may be crimped, twisted, or curled, or a combination thereof including crimped, twisted, and curled.
In a certain embodiment, one or both of the upper and lower acquisition layers 52 and 54 may comprise a non-woven, which may be hydrophilic. Further, according to a certain embodiment, one or both of the upper and lower acquisition layers 52 and 54 may comprise the chemically cross-linked cellulosic fibers, which may or may not form part of a nonwoven material. According to an exemplary embodiment, the upper acquisition layer 52 may comprise a nonwoven, without the cross-linked cellulosic fibers, and the lower acquisition layer 54 may comprise the chemically cross-linked cellulosic fibers. Further, according to an embodiment, the lower acquisition layer 54 may comprise the chemically cross-linked cellulosic fibers mixed with other fibers such as natural or synthetic polymeric fibers. According to exemplary embodiments, such other natural or synthetic polymeric fibers may include high surface area fibers, thermoplastic binding fibers, polyethylene fibers, polypropylene fibers, PET fibers, rayon fibers, lyocell fibers, and mixtures thereof. According to a particular embodiment, the lower acquisition layer 54 has a total dry weight, the cross-linked cellulosic fibers are present on a dry weight basis in the upper acquisition layer in an amount from about 30% to about 95% by weight of the lower acquisition layer 54, and the other natural or synthetic polymeric fibers are present on a dry weight basis in the lower acquisition layer 54 in an amount from about 70% to about 5% by weight of the lower acquisition layer 54. According to another embodiment, the cross-linked cellulosic fibers are present on a dry weight basis in the first acquisition layer in an amount from about 80% to about 90% by weight of the lower acquisition layer 54, and the other natural or synthetic polymeric fibers are present on a dry weight basis in the lower acquisition layer 54 in an amount from about 20% to about 10% by weight of the lower acquisition layer 54.
According to a certain embodiment, the lower acquisition layer 54 desirably has a high fluid uptake capability. Fluid uptake is measured in grams of absorbed fluid per gram of absorbent material and is expressed by the value of “maximum uptake.” A high fluid uptake corresponds therefore to a high capacity of the material and is beneficial, because it ensures the complete acquisition of fluids to be absorbed by an acquisition material. According to exemplary embodiments, the lower acquisition layer 54 has a maximum uptake of about 10 g/g.
A relevant attribute of the upper acquisition layer 54 is its Median Desorption Pressure, MDP. The MDP is a measure of the capillary pressure that is required to dewater the lower acquisition layer 54 to about 50% of its capacity at 0 cm capillary suction height under an applied mechanical pressure of 0.3 psi. Generally, a relatively lower MDP may be useful. The lower MDP may allow the lower acquisition layer 54 to more efficiently drain the upper acquisition material. Without wishing to be bound by theory, a given distribution material may have a definable capillary suction. The ability of the lower acquisition layer 54 to move liquid vertically via capillary forces will be directly impacted by gravity and the opposing capillary forces associated with desorption of the upper acquisition layer. Minimizing these capillary forces may positively impact the performance of the lower acquisition layer 54. However, in a certain embodiment the lower acquisition layer 54 may also have adequate capillary absorption suction in order to drain the layers above (upper acquisition layer 52 and topsheet 18, in particular) and to temporarily hold liquid until the liquid can be partitioned away by the absorbent core components. Therefore, in a certain embodiment, the lower acquisition layer 54 may have a minimum MDP of greater than 5 cm. Further, according to exemplary embodiments, the lower acquisition layer 54 has an MDP value of less than about 20.5 cm H2O, or less than about 19 cm H2O, or less than about 18 cm H2O to provide for fast acquisition.
The methods for determining MDP and maximum uptake are disclosed in U.S. patent application Ser. No. 11/600,691 (Flohr et al.). For example, according to a first embodiment, the lower acquisition layer 54 may comprise about 70% by weight of chemically cross-linked cellulose fibers, about 10% by weight polyester (PET), and about 20% by weight untreated pulp fibers. According to a second embodiment, the lower acquisition layer 54 may comprise about 70% by weight chemically cross-linked cellulose fibers, about 20% by weight lyocell fibers, and about 10% by weight PET fibers. According to a third embodiment, the lower acquisition layer 54 may comprise about 68% by weight chemically cross-linked cellulose fibers, about 16% by weight untreated pulp fibers, and about 16% by weight PET fibers. In one embodiment, the lower acquisition layer 54 may comprise from about 90-100% by weight chemically cross-linked cellulose fibers.
Suitable non-woven materials for the upper and lower acquisition layers 52 and 54 include, but are not limited to SMS material, comprising a spunbonded, a melt-blown and a further spunbonded layer. In certain embodiments, permanently hydrophilic non-wovens, and in particular, nonwovens with durably hydrophilic coatings are desirable. Another suitable embodiment comprises a SMMS-structure. In certain embodiments, the non-wovens are porous.
In certain embodiments, suitable non-woven materials may include, but are not limited to synthetic fibers, such as PE, PET, and PP. As polymers used for nonwoven production may be inherently hydrophobic, they may be coated with hydrophilic coatings. One way to produce nonwovens with durably hydrophilic coatings, is via applying a hydrophilic monomer and a radical polymerization initiator onto the nonwoven, and conducting a polymerization activated via UV light resulting in monomer chemically bound to the surface of the nonwoven as described in co-pending U.S. Patent Publication No. 2005/0159720. Another way to produce nonwovens with durably hydrophilic coatings is to coat the nonwoven with hydrophilic nanoparticles as described in co-pending applications U.S. Pat. No. 7,112,621 to Rohrbaugh et al. and in PCT Application Publication WO 02/064877.
Typically, nanoparticles have a largest dimension of below 750 nm. Nanoparticles with sizes ranging from 2 to 750 nm may be economically produced. An advantage of nanoparticles is that many of them can be easily dispersed in water solution to enable coating application onto the nonwoven, they typically form transparent coatings, and the coatings applied from water solutions are typically sufficiently durable to exposure to water. Nanoparticles can be organic or inorganic, synthetic or natural. Inorganic nanoparticles generally exist as oxides, silicates, and/or, carbonates. Typical examples of suitable nanoparticles are layered clay minerals (e.g., LAPONITE™ from Southern Clay Products, Inc. (USA), and Boehmite alumina (e.g., Disperal P2™ from North American Sasol. Inc.). According to a certain embodiment, a suitable nanoparticle coated non-woven is that disclosed in the co-pending patent application Ser. No. 10/758,066 entitled “Disposable absorbent article comprising a durable hydrophilic core wrap” to Ekaterina Anatolyevna Ponomarenko and Manias NMN Schmidt.
Further useful non-wovens are described in U.S. Pat. No. 6,645,569 to Cramer et al., U.S. Pat. No. 6,863,933 to Cramer et al., U.S. Pat. No. 7,112,621 to Rohrbaugh et al., and co-pending patent application Ser. No. 10/338,603 to Cramer et al. and Ser. No. 10/338,610 to Cramer et al.
In some cases, the nonwoven surface can be pre-treated with high energy treatment (corona, plasma) prior to application of nanoparticle coatings. High energy pre-treatment typically temporarily increases the surface energy of a low surface energy surface (such as PP) and thus enables better wetting of a nonwoven by the nanoparticle dispersion in water.
Notably, permanently hydrophilic non-wovens are also useful in other parts of an absorbent article. For example, topsheets and absorbent core layers comprising permanently hydrophilic non-wovens as described above have been found to work well.
According to a certain embodiment, the upper acquisition layer 52 may comprise a material that provides good recovery when external pressure is applied and removed. Further, according to a certain embodiment, the upper acquisition layer 52 may comprise a blend of different fibers selected, for example from the types of polymeric fibers described above. In some embodiments, at least a portion of the fibers may exhibit a spiral-crimp which has a helical shape. In some embodiments, the upper acquisition layer 52 may comprise fibers having different degrees or types of crimping, or both. For example, one embodiment may include a mixture of fibers having about 8 to about 12 crimps per inch (cpi) or about 9 to about 10 cpi, and other fibers having about 4 to about 8 cpi or about 5 to about 7 cpi. Different types of crimps include, but are not limited to a 2D crimp or “flat crimp” and a 3D or spiral-crimp. According to a certain embodiment, the fibers may include bi-component fibers, which are individual fibers each comprising different materials, usually a first and a second polymeric material. It is believed that the use of side-by-side bi-component fibers is beneficial for imparting a spiral-crimp to the fibers.
The upper acquisition layer 52 may be stabilized by a latex binder, for example a styrene-butadiene latex binder (SB latex), in a certain embodiment. Processes for obtaining such lattices are known, for example, from EP 149 880 (Kwok) and US 2003/0105190 (Diehl et al.). In certain embodiments, the binder may be present in the upper acquisition layer 52 in excess of about 12%, about 14% or about 16% by weight. For certain embodiments, SB latex is available under the trade name GENFLO™ 3160 (OMNOVA Solutions Inc.; Akron, Ohio).
The absorbent core 14 in
Likewise, as best illustrated in
The substrate 64 of the first absorbent layer 60 may be referred to as a dusting layer and has a first surface 78 which faces the backsheet 20 of the diaper 10 and a second surface 80 which faces the absorbent particulate polymer material 66. Likewise, the substrate 72 of the second absorbent layer 62 may be referred to as a core cover and has a first surface 82 facing the topsheet 18 of the diaper 10 and a second surface 84 facing the absorbent particulate polymer material 74. The first and second substrates 64 and 72 may be adhered to one another with adhesive about the periphery to form an envelope about the absorbent particulate polymer materials 66 and 74 to hold the absorbent particulate polymer material 66 and 74 within the absorbent core 14.
According to a certain embodiment, the substrates 64 and 72 of the first and second absorbent layers 60 and 62 may be a non-woven material, such as those nonwoven materials described above. In certain embodiments, the non-wovens are porous and in one embodiment has a pore size of about 32 microns.
As illustrated in
The grid pattern shown in
The size of the land areas 94 in the grid patterns 92 may vary. According to certain embodiments, the width 119 of the land areas 94 in the grid patterns 92 ranges from about 8 mm to about 12 mm. In a certain embodiment, the width of the land areas 94 is about 10 mm. The junction areas 96, on the other hand, in certain embodiments, have a width or larger span of less than about 5 mm, less than about 3 mm, less than about 2 mm, less than about 1.5 mm, less than about 1 mm, or less than about 0.5 mm.
The small clusters 90 of absorbent particulate polymer material 66 and 74 are thinner than the large clusters 91 of absorbent particulate polymer material 66 and 74 and impart a lower basis weight of absorbent particulate polymer material 66 and 74 to the area of the absorbent core 14 in which the small clusters 90 are located. Likewise, the large clusters 91 of absorbent particulate polymer material 66 and 74 are thicker than the small clusters 90 of absorbent particulate polymer material 66 and 74 and impart a higher basis weight of absorbent particulate polymer material 66 and 74 to the area of the absorbent core 14 in which the large clusters 91 are located. This creates a varied profile of absorbent particulate polymer material across the absorbent core 14.
As shown in
As best seen in
The first and second absorbent layers 60 and 62 may be combined together to form the absorbent core 14 such that the grid patterns 92 of the respective first and second absorbent layers 62 and 64 are offset from one another along the length and/or width of the absorbent core 14. The respective grid patterns 92 may be offset such that the absorbent particulate polymer material 66 and 74 is substantially continuously distributed across the absorbent particulate polymer area 114. In a certain embodiment, absorbent particulate polymer material 66 and 74 is substantially continuously distributed across the absorbent particulate polymer material area 114 despite the individual grid patterns 92 comprising absorbent particulate polymer material 66 and 74 discontinuously distributed across the first and second substrates 64 and 72 in clusters 90 and 91. In a certain embodiment, the grid patterns may be offset such that the land areas 94 of the first absorbent layer 60 face the junction areas 96 of the second absorbent layer 62 and the land areas of the second absorbent layer 62 face the junction areas 96 of the first absorbent layer 60. When the land areas 94 and junction areas 96 are appropriately sized and arranged, the resulting combination of absorbent particulate polymer material 66 and 74 is a substantially continuous layer of absorbent particular polymer material across the absorbent particulate polymer material area 114 of the absorbent core 14 (i.e. first and second substrates 64 and 72 do not form a plurality of pockets, each containing a cluster 90 of absorbent particulate polymer material 66 therebetween). In a certain embodiment, respective grid patterns 92 of the first and second absorbent layer 60 and 62 may be substantially the same.
In a certain embodiment as illustrated in
In the embodiment illustrated in
In the embodiment illustrated in
Although the embodiment illustrated in
In
Another embodiment of an absorbent core 14′ is illustrated in
Although the absorbent core 14′ illustrated in
Another embodiment of an absorbent core 14″ is illustrated in
The amount of absorbent particulate polymer material 66 and 74 present in the absorbent core 14 may vary, but in certain embodiments, is present in the absorbent core in an amount greater than about 80% by weight of the absorbent core, or greater than about 85% by weight of the absorbent core, or greater than about 90% by weight of the absorbent core, or greater than about 95% by weight of the core. In a particular embodiment, the absorbent core 14 consists essentially of the first and second substrates 64 and 72, the absorbent particulate polymer material 66 and 74, and the thermoplastic adhesive composition 68 and 76. In an embodiment, the absorbent core 14 may be substantially cellulose free.
According to certain embodiments, the weight of absorbent particulate polymer material 66 and 74 in at least one freely selected first square measuring 1 cm×1 cm may be at least about 10%, or 20%, or 30%, 40% or 50% higher than the weight of absorbent particulate polymer material 66 and 74 in at least one freely selected second square measuring 1 cm×1 cm. In a certain embodiment, the first and the second square are centered about the longitudinal axis.
The absorbent particulate polymer material area, according to an exemplary embodiment, may have a relatively narrow width in the crotch area of the absorbent article for increased wearing comfort. Hence, the absorbent particulate polymer material area, according to an embodiment, may have a width as measured along a transverse line which is positioned at equal distance to the front edge and the rear edge of the absorbent article, which is less than about 100 mm, 90 mm, 80 mm, 70 mm, 60 mm or even less than about 50 mm.
It has been found that, for most absorbent articles such as diapers, the liquid discharge occurs predominately in the front half of the diaper. The front half of the absorbent core 14 should therefore comprise most of the absorbent capacity of the core. Thus, according to certain embodiments, the front half of said absorbent core 14 may comprise more than about 60% of the superabsorbent material, or more than about 65%, 70%, 75%, 80%, 85%, or 90% of the superabsorbent material.
In certain embodiments, the absorbent core 14 may further comprise any absorbent material that is generally compressible, conformable, non-irritating to the wearer's skin, and capable of absorbing and retaining liquids such as urine and other certain body exudates. In such embodiments, the absorbent core 14 may comprise a wide variety of liquid-absorbent materials commonly used in disposable diapers and other absorbent articles such as comminuted wood pulp, which is generally referred to as airfelt, creped cellulose wadding, melt blown polymers, including co-form, chemically stiffened, modified or cross-linked cellulosic fibers, tissue, including tissue wraps and tissue laminates, absorbent foams, absorbent sponges, or any other known absorbent material or combinations of materials. The absorbent core 14 may further comprise minor amounts (typically less than about 10%) of materials, such as adhesives, waxes, oils and the like.
Exemplary absorbent structures for use as the absorbent assemblies are described in U.S. Pat. No. 4,610,678 (Weisman et al.); U.S. Pat. No. 4,834,735 (Alemany et al.); U.S. Pat. No. 4,888,231 (Angstadt); U.S. Pat. No. 5,260,345 (DesMarais et al.); U.S. Pat. No. 5,387,207 (Dyer et al.); U.S. Pat. No. 5,397,316 (LaVon et al.); and U.S. Pat. No. 5,625,222 (DesMarais et al.).
In a certain embodiment best illustrated in
The thermoplastic adhesive material 68 and 76 may serve to cover and at least partially immobilize the absorbent particulate polymer material 66 and 74. In one embodiment of the present invention, the thermoplastic adhesive material 68 and 76 can be disposed essentially uniformly within the absorbent particulate polymer material 66 and 74, between the polymers. However, in a certain embodiment, the thermoplastic adhesive material 68 and 76 may be provided as a fibrous layer which is at least partially in contact with the absorbent particulate polymer material 66 and 74 and partially in contact with the substrate layers 64 and 72 of the first and second absorbent layers 60 and 62.
Thereby, the thermoplastic adhesive material 68 and 76 may provide cavities to cover the absorbent particulate polymer material 66 and 74, and thereby immobilizes this material. In a further aspect, the thermoplastic adhesive material 68 and 76 bonds to the substrates 64 and 72 and thus affixes the absorbent particulate polymer material 66 and 74 to the substrates 64 and 72. Thus, in accordance with certain embodiments, the thermoplastic adhesive material 68 and 76 immobilizes the absorbent particulate polymer material 66 and 74 when wet, such that the absorbent core 14 achieves an absorbent particulate polymer material loss of no more than about 70%, 60%, 50%, 40%, 30%, 20%, 10% according to the Wet Immobilization Test described herein. Some thermoplastic adhesive materials will also penetrate into both the absorbent particulate polymer material 66 and 74 and the substrates 64 and 72, thus providing for further immobilization and affixation. Of course, while the thermoplastic adhesive materials disclosed herein provide a much improved wet immobilization (i.e., immobilization of absorbent material when the article is wet or at least partially loaded), these thermoplastic adhesive materials may also provide a very good immobilization of absorbent material when the absorbent core 14 is dry. The thermoplastic adhesive material 68 and 76 may also be referred to as a hot melt adhesive.
Without wishing to be bound by theory, it has been found that those thermoplastic adhesive materials which are most useful for immobilizing the absorbent particulate polymer material 66 and 74 combine good cohesion and good adhesion behavior. Good adhesion may promote good contact between the thermoplastic adhesive material 68 and 76 and the absorbent particulate polymer material 66 and 74 and the substrates 64 and 72. Good cohesion reduces the likelihood that the adhesive breaks, in particular in response to external forces, and namely in response to strain. When the absorbent core 14 absorbs liquid, the absorbent particulate polymer material 66 and 74 swells and subjects the thermoplastic adhesive material 68 and 76 to external forces. In certain embodiments, the thermoplastic adhesive material 68 and 76 may allow for such swelling, without breaking and without imparting too many compressive forces, which would restrain the absorbent particulate polymer material 66 and 74 from swelling.
In accordance with certain embodiments, the thermoplastic adhesive material 68 and 76 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 68 and 76 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. To improve the adhesion of the thermoplastic adhesive material 68 and 76 to the substrates 64 and 72 or to any other layer, in particular any other non-woven layer, such layers may be pre-treated with an auxiliary adhesive.
In certain embodiments, the thermoplastic adhesive material 68 and 76 will meet at least one, or several, or all of the following parameters:
An exemplary thermoplastic adhesive material 68 and 76 may have a storage modulus G′ measured at 20° C. of at least 30,000 Pa and less than 300,000 Pa, or less than 200,000 Pa, or between 140,000 Pa and 200,000 Pa, or less than 100,000 Pa. In a further aspect, the storage modulus G′ measured at 35° C. may be greater than 80,000 Pa. In a further aspect, the storage modulus G′ measured at 60° C. may be less than 300,000 Pa and more than 18,000 Pa, or more than 24,000 Pa, or more than 30,000 Pa, or more than 90,000 Pa. In a further aspect, the storage modulus G′ measured at 90° C. may be less than 200,000 Pa and more than 10,000 Pa, or more than 20,000 Pa, or more then 30,000 Pa. The storage modulus measured at 60° C. and 90° C. may be a measure for the form stability of the thermoplastic adhesive material at elevated ambient temperatures. This value is particularly important if the absorbent product is used in a hot climate where the thermoplastic adhesive material would lose its integrity if the storage modulus G′ at 60° C. and 90° C. is not sufficiently high.
G′ is measured using a rheometer as schematically shown in
The absorbent core 14 may also comprise an auxiliary adhesive layer 69. The auxiliary adhesive may be deposited on the first and second substrates 64 and 72 of the respective first and second absorbent layers 60 and 62 before application of the absorbent particulate polymer material 66 and 74 for enhancing adhesion of the absorbent particulate polymer materials 66 and 74 and the thermoplastic adhesive material 68 and 76 to the respective substrates 64 and 72. The auxiliary glue 69 may also aid in immobilizing the absorbent particulate polymer material 66 and 74 and may comprise the same thermoplastic adhesive material as described hereinabove or may also comprise other adhesives including but not limited to sprayable hot melt adhesives, such as H.B. Fuller Co. (St. Paul, Minn.) Product No. HL-1620-B. The auxiliary glue may be applied to the substrates 64 and 72 by any suitable means, but according to certain embodiments, may be applied in about 0.5 to about 1 mm wide slots spaced about 0.5 to about 2 mm apart.
The cover layer 70 shown in
A printing system 130 for making an absorbent core 14 in accordance with an embodiment of this invention is illustrated in
The first printing unit 132 may comprise a first auxiliary adhesive applicator 136 for applying an auxiliary adhesive 69 to the substrate 64, which may be a nonwoven web, a first rotatable support roll 140 for receiving the substrate 64, a hopper 142 for holding absorbent particulate polymer material 66, a printing roll 144 for transferring the absorbent particulate polymer material 66 to the substrate 64, and a thermoplastic adhesive material applicator 146 for applying the thermoplastic adhesive material 68 to the substrate 64 and the absorbent particulate polymer 66 material thereon.
The second printing unit 134 may comprise a second auxiliary adhesive applicator 148 for applying an auxiliary adhesive 73 to the second substrate 72, a second rotatable support roll 152 for receiving the second substrate 72, a second hopper 154 for holding the absorbent particulate polymer material 74, a second printing roll 156 for transferring the absorbent particulate polymer material 74 from the hopper 154 to the second substrate 72, and a second thermoplastic adhesive material applicator 158 for applying the thermoplastic adhesive material 76 to the second substrate 72 and the absorbent particulate polymer material 74 thereon.
The printing system 130 also includes a guide roller 160 for guiding the formed absorbent core from a nip 162 between the first and second rotatable support rolls 140 and 152.
The first and second auxiliary applicators 136 and 148 and the first and second thermoplastic adhesive material applicators 146 and 158 may be a nozzle system which can provide a relatively thin but wide curtain of thermoplastic adhesive material.
Turning to
As also illustrated in
The first printing roll 144 is designed to produce a certain embodiment like the absorbent core 14 illustrated in
Other methods of delivering a varying profile of absorbent particulate polymer basis weights to the absorbent core 14 includes, but is not limited to, applying a higher vacuum in sections of the first and second rotatable support rolls 140 and 152 where more absorbent particulate polymer material is desired or, when the absorbent particulate polymer material is delivered to the absorbent core substrate 64 pneumatically, such as when combining cellulosic fibers with absorbent particulate polymer material, directing the air stream carrying the absorbent particulate polymer material and cellulosic fibers to areas of the absorbent core substrate where a higher basis weight of absorbent particulate polymer material is desired.
In operation, the printing system 130 receives the first and second substrate 64 and 72 into the first and second printing units 132 and 134, respectively, the first substrate 64 is drawn by the rotating first support roll 140 past the first auxiliary adhesive applicator 136 which applies the first auxiliary adhesive to the first substrate 64 in a pattern such as described hereinabove. A vacuum (not shown) within the first support roll 140 draws the first substrate 64 against the vertical support grid 166 and holds the first substrate 64 against the first support roll 140. This presents an uneven surface on the first substrate 64. Due to gravity, or by using the vacuum means, the substrate 64 will follow the contours of the uneven surface and thereby the substrate 64 will assume a mountain and valley shape. The absorbent particulate polymer material 66 may accumulate in the valleys presented by the substrate 64. The first support roll 140 then carries the first substrate 64 past the rotating first printing roll 144 which transfers the absorbent particulate polymer material 66 from the first hopper 142 to the first substrate 64 in the grid pattern 92 which is best illustrated in
Hence, the uneven surface of the vented support grid 166 of the support rolls 140 and 152 determines the distribution of absorbent particulate polymeric material 66 and 74 throughout the absorbent core 14 and likewise determines the pattern of junction areas 96.
Meanwhile, the second rotatable support roll draws the second substrate 72 past the second auxiliary adhesive applicator 148 which applies an auxiliary adhesive to the second substrate 72 in a pattern such as is described hereinabove. The second rotatable support roll 152 then carries the second substrate 72 past the second printing roll 156 which transfers the absorbent particulate polymer material 74 from the second hopper 154 to the second substrate 72 and deposits the absorbent particulate polymer material 74 in the grid pattern 92 on the second substrate 72 in the same manner as described with regard to the first printing unit 132 above. The second thermoplastic adhesive material applicator 158 then applies the thermoplastic adhesive material 76 to cover the absorbent particulate polymer material 74 on the second substrate 72. The printed first and second substrates 64 and 72 then pass through the nip 162 between the first and second support rolls 140 and 152 for compressing the first absorbent layer 60 and second absorbent layer 62 together to form the absorbent core 14.
In an optional further process step a cover layer 70 may be placed upon the substrates 64 and 72, the absorbent particulate polymer material 66 and 74, and the thermoplastic adhesive material 68 and 76. In another embodiment, the cover layer 70 and the respective substrate 64 and 72 may be provided from a unitary sheet of material. The placing of the cover layer 70 onto the respective substrate 64 and 72 may then involve the folding of the unitary piece of material.
Absorbent articles such as the diapers 10 made in accordance with embodiments of this invention may be folded and packaged for distribution and sale. Absorbent articles are typically bi-folded, but may also be tri-folded. After folding, the folded absorbent articles may be stacked to form a stack comprising a plurality of absorbent articles. The stack may then be compressed and encased in a packaging material such as a bag, a pouch, a box, or the like.
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 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 invention. 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 invention 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 invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
This application is a continuation of application Ser. No. 12/485,953, filed on Jun. 17, 2009, which claims the benefit of U.S. Provisional Application No. 61/077,498, filed on Jul. 2, 2008.
| Number | Date | Country | |
|---|---|---|---|
| 61077498 | Jul 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12485953 | Jun 2009 | US |
| Child | 15138244 | US |
