Patent Application
20240315889
This invention relates to an individually packaged absorbent article provided in a folded configuration and comprising a wrapper releasably affixed to the absorbent article, where the wrapper comprises a material comprising natural fibers.
Users/consumers of absorbent articles, such as feminine hygiene pads, have developed a number of varying expectations and preferences for such products over the years, as the products themselves have evolved. These expectations and preferences include (in no particular order) (1) that the absorbent article have suitable absorption performance such that it will readily accept, absorb, contain, isolate, and effectively retain all fluid discharged, away from the user's skin and without leaking, over a normal time of use/wear; (2) that the absorbent article be as thin (non-bulky), flexible and pliable as possible for purposes of comfort, accommodation of the wearer's body movements, and discreetness of wear under clothing; and (3) that the absorbent article and its wrapping provide for convenient and discreet carrying, easy opening and access to the absorbent article, as well as convenient disposal of used absorbent articles. More recently, consumers of absorbent articles, such as feminine hygiene pads, are also seeking products that comprise natural materials, bio-sourced materials, and/or recycled materials. And, in the context of disposal, consumers are seeking products comprising components or packaging that is bio-degradable, compostable, recyclable, reusable, and/or otherwise contributes to reduced landfill waste.
Modern absorbent articles, such as feminine hygiene pads, are highly optimized to meet consumers' varying expectations and preferences. For example, many feminine hygiene pads are folded and compacted so that, once packaged, the articles are thin and discrete to carry in a purse. Such feminine hygiene pads are typically folded and wrapped individually with a thin, flexible wrapper, which may subsequently be used for disposal of used product. The wrappers are typically made of plastic, such as polyethylene film. Plastic is generally preferred because it can withstand the rigors of the manufacturing process, due to its ability to flex and stretch. However, there is growing public demand for alternatives to plastic and non-plastic based wrappers. The replacement of a plastic wrapper material with a wrapper material comprising natural fibers, such as paper, in existing manufacturing processes may present challenges; materials comprising natural fibers may have less resistance to the stresses normally encountered during such manufacturing processes.
There is therefore a need to provide a disposable absorbent article individually wrapped in a material comprising natural fibers, which can be manufactured under existing process conditions at high speed.
In some embodiments, an individually packaged absorbent article comprises: an absorbent article comprising a liquid permeable topsheet, a liquid impermeable backsheet, and an absorbent layer disposed between the topsheet and the backsheet, wherein the outward-facing surface of the backsheet has an adhesive disposed thereon; and a wrapper overlaying the outward-facing surface of the backsheet, wherein the wrapper comprises a sheet material having a basis weight of about 30 gsm to about 85 gsm, wherein the sheet material comprises creped paper, and wherein the creped paper has a stretch of at least about 10% to about 30%, wherein the individually packaged absorbent article is provided in a folded configuration, the absorbent article and the wrapper folded together about at least one fold line.
In some embodiments, an individually packaged absorbent article comprises: an absorbent article comprising a liquid permeable topsheet, a liquid impermeable backsheet, and an absorbent layer disposed between the topsheet and the backsheet, wherein the outward-facing surface of the backsheet has an adhesive disposed thereon; and a wrapper overlaying the outward-facing surface of the backsheet, wherein the wrapper comprises a sheet material having a basis weight of about 30 gsm to about 85 gsm, wherein the sheet material comprises creped paper and has a folding angle of about 45° to about 90°, wherein the individually packaged absorbent article is provided in a folded configuration, the absorbent article and the wrapper folded together about at least one fold line.
In some embodiments, an individually packaged absorbent article comprises: an absorbent article comprising a liquid permeable topsheet, a liquid impermeable backsheet, and an absorbent layer disposed between the topsheet and the backsheet, wherein the outward-facing surface of the backsheet has an adhesive disposed thereon; and a wrapper overlaying the outward-facing surface of the backsheet, wherein the wrapper comprises a sheet material having a basis weight of about 30 gsm to about 85 gsm, wherein the sheet material has a MD web modulus at 1%-2% strain of less than about 600 N/cm, wherein the individually packaged absorbent article is provided in a folded configuration, the absorbent article and the wrapper folded together about at least one fold line.
The term “absorbent article” as used herein refers to devices which absorb and contain exudates, and, more specifically, refers to devices which 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 of the present disclosure include, but are not limited to, diapers, adult incontinence briefs, training pants, diaper holders, diaper outer covers, absorbent inserts for the diaper outer covers, feminine hygiene pads/menstrual pads, incontinence pads, liners, pantiliners, tampons, durable feminine hygiene pants/menstrual pants, disposable swim pants, and the like.
The term “renewable” is synonymous with the terms “biobased,” “sustainable,” “sustainably derived,” or “from sustainable sources” and means bio-derived (derived from a renewable resource, e.g., plants) or “non-geologically derived.” “Geologically derived” means derived from, for example, petrochemicals, natural gas, or coal. “Geologically derived” materials cannot be easily replenished or regrown (e.g., in contrast to plant- or algae-produced oils).
As used herein, the term “renewable component” refers to a component that is derived from renewable feedstock and contains renewable carbon. A renewable feedstock is a feedstock that is derived from a renewable resource, e.g., plants, and non-geologically derived. A material may be partially renewable (less than 100% renewable carbon content, from about 1% to about 50% renewable carbon content) or 100% renewable (100% renewable carbon content). A renewable material may be blended with a nonrenewable material.
“Renewable carbon” may be assessed according to the “Assessment of the Biobased Content of Materials” method, ASTM D6866.
The term “substantially free of” or “substantially free from” as used herein refers to either the complete absence of an ingredient or a minimal amount thereof merely as impurity or unintended byproduct of another ingredient. A composition that is “substantially free” of/from a component means that the composition comprises less than about 5%, 3%, 2%, 1%, 0.5%, 0.25%, 0.1%, 0.05%, or 0.01%, or even 0%, by weight of the composition, of the component.
The term “natural fibers” as used herein, refers to fibers which comprise cellulose-based fibers, bamboo based fibers, and the like. Natural fibers also refers to nonwoody fibers, such as cotton, abaca, kenaf, sabai grass, flax, esparto grass, straw, jute hemp, bagasse, milkweed floss fibers, and pineapple leaf fibers; and woody, wood, or pulp fibers such as those obtained from deciduous and coniferous trees, including softwood fibers, such as northern and southern softwood kraft fibers; hardwood fibers, such as eucalyptus, maple, birch, and aspen. Pulp fibers can be prepared in high-yield or low-yield forms and can be pulped in any known method of chemical or mechanical pulping, including kraft, sulfite, high-yield pulping methods. The natural fibers of the present disclosure may be recycled natural fibers, virgin natural fibers or mixes thereof. Additionally, for good mechanical properties in natural fibers, it can be desirable that the natural fibers be relatively undamaged and largely unrefined or only lightly refined. A natural fiber pulp may be characterized by a Canadian Standard Freeness value, which characterizes the change in the drainage rate of a pulp and is widely used to represent the change in fiber properties during beating and refining. The Canadian Standard Freeness value has been shown to relate to the surface conditions and swelling of the pulp fibers and may be used to control fiber properties by selecting the optimal level of refining energy needed for a selected grade of pulp. The Canadian Standard Freeness value may vary depending on the fiber type, fiber morphology, and the concentration of mass in the fiber suspension. The Canadian Standard Freeness value may be determined according to standardized test procedures, e.g., TAPPI T-227 om-17 (2017).
The term “cellulose-based fibers,” as used herein, includes cellulose fibers, such as wood fiber, and cotton, regenerated cellulose fiber, such as rayon or cuprammonium rayon, and high pulping yield fibers. The term “cellulose-based fibers” also includes chemically treated natural fibers, such as mercerized pulps, chemically stiffened or crosslinked fibers, or sulfonated fibers. Also included are mercerized natural fibers, regenerated natural cellulosic fibers, cellulose produced by microbes, the rayon process, cellulose dissolution and coagulation spinning processes, and other cellulosic material or cellulosic derivatives. Other cellulose-based fibers included are paper broke or recycled fibers and high yield fibers. High yield pulp fibers are those fibers produced by pulping processes providing a yield of about 65% or greater, more specifically about 75% or greater, and still more specifically about 75% to about 95%, where yield is the resulting amount of processed fibers expressed as a percentage of the initial wood mass. Such pulping processes include bleached chemithermomechanical pulp (BCTMP), chemithermomechanical pulp (CTMP), pressure/pressure thermomechanical pulp (PTMP), thermomechanical pulp (TMP), thermomechanical chemical pulp (TMCP), high yield sulfite pulps, and high yield Kraft pulps, all of which leave the resulting fibers with high levels of lignin but are still considered to be natural fibers. High yield fibers are well known for their stiffness in both dry and wet states relative to typical chemically pulped fibers.
The term “machine direction” or “MD”, as used herein, refers to the path that material, such as a web, follows through a manufacturing process.
The term “cross-machine direction” or “CD”, as used herein, refers to the path that is perpendicular to the machine direction in the plane of the web.
With respect to an absorbent article, such as a feminine hygiene pad, that is open and laid out flat on a horizontal planar surface, “lateral” refers to a direction perpendicular to the longitudinal direction and parallel the horizontal planar surface. “Width” refers to a dimension measured along a lateral direction.
With respect to an absorbent article, such as a feminine hygiene pad, that is open and laid out flat on a horizontal planar surface and having a length measured from its forwardmost end to its rearwardmost end, “longitudinal” refers to a direction parallel with the line along which the length is measured, and parallel to the horizontal planar surface. “Length” refers to a dimension measured in the longitudinal direction.
With respect to an absorbent article, such as a feminine hygiene pad, the terms “front”, “rear”, “forward” and “rearward” relate to features or regions of the article in a position as it would ordinarily be worn by a user, and the front and rear of the user's body when standing.
With respect to an absorbent article, such as a feminine hygiene pad, that is open and laid out flat on a horizontal planar surface, “z-direction” refers to a direction perpendicular to the horizontal planar surface. When the article is being worn by a user (and thus in a curved configuration), “z-direction” at any particular point location on the article refers to a direction normal to the wearer-facing surface of the article at the particular point location.
With respect to an absorbent article, such as a feminine hygiene pad, “wearer-facing” is a relative locational term referring to a feature of a component or structure of the article that, when in use, lies closer to the wearer than another feature of the component or structure that lies along the same z-direction. For example, a topsheet has a wearer-facing surface that lies closer to the wearer than the opposite, outward-facing surface of the topsheet.
With respect to an absorbent article, such as a feminine hygiene pad, “outward-facing” or “garment-facing” is a relative locational term referring to a feature of a component or structure of the article that, when in use, lies farther from the wearer than another feature of the component or structure that lies along the same z-direction. For example, a topsheet has an outward-facing or garment-facing surface that lies farther from the wearer than the opposite, wearer-facing surface of the topsheet.
An absorbent feminine hygiene pad may have any shape known in the art for feminine hygiene articles, including the generally symmetric “hourglass” shape, as well as pear shapes, bicycle-seat shapes, trapezoidal shapes, wedge shapes or other shapes that have one end wider than the other. Sanitary napkins and pantiliners can also be provided with lateral extensions known in the art as “flaps” or “wings”). Such extensions can serve a number of purposes, including, but not limited to, protecting the wearer's panties from soiling and keeping the sanitary napkin secured in place. The absorbent article has a wearer-facing side that contacts the user's body during use and an opposite, garment-facing or outward-facing side that contacts the user's undergarments during use.
In some embodiments, the wrapper may be folded along three fold lines H, such as illustrated in
The second configuration is the book jacket fold configuration and is illustrated in
Referring to
The absorbent pad 20 may include opposing wings (not shown) extending laterally from the longitudinal side edges of the pad by a comparatively greater width dimension than the main portion of the pad. Wings may be formed of lateral extensions of the material forming the topsheet 20, backsheet 30, or both together. The wings of the absorbent pads of the present disclosure may be integrally formed as part of the topsheet. In some forms, the wings may be integrally formed as part of the backsheet. In some forms, the wings may be integrally formed as part of the topsheet and the backsheet. In some forms, the wings may be integrally formed with additional layers—described herein—of the absorbent article. Yet in other forms, the wings may be formed discretely and joined to the chassis. The outward-facing surface of the backsheet forming the undersides of the main portion and the outward-facing surface of the wings may have deposits of adhesive 70 thereon. If present, the wings may be folded over the wearer-facing surface of the pad and, following such folding, a release film or paper may be applied to the portions of the wings having adhesive deposited thereon, to cover and protect the adhesive prior to use.
Adhesive deposits 70 may be provided to enable the user to adhere the pad to the inside of her underpants in the crotch region thereof. Adhesive deposits 70 on the outward-facing surface of the wings allow the user to secure the wings around the edges of the leg openings of the underpants and adhere them to the outside/underside of the underpants in the crotch region, providing supplemental holding support and helping guard the leg opening edges of the underpants against soiling. When pad 20 is wrapped and folded, adhesive deposits 70 may be covered by the wrapper 80, to shield them from contact with other surfaces until the user is ready to remove the wrapper 80 and place the pad 20 for use. Adhesive deposits 70 on the wings and/or the pad 20 may be covered by one or more removable sheets of release film or paper.
The topsheet 30 may be formed of any suitable liquid permeable web material. Referring back to
Topsheet 30 may be formed of any liquid pervious web material that is suitably compliant, soft feeling, and non-irritating to the wearer's skin. Suitable topsheet materials include a liquid pervious material that contacts the body of the wearer and permits menstrual fluid discharges to rapidly penetrate through it. Some suitable examples of topsheet materials include films, nonwovens, laminate structures including film/nonwoven layers, film/film layers, and nonwoven/nonwoven layers. Other exemplary topsheet materials and designs are disclosed in U.S. Patent Application Publication Nos. 2016/0129661, 2016/0167334, and 2016/0278986.
A suitable topsheet can be made of various materials such as woven and nonwoven materials; apertured film materials including apertured formed thermoplastic films, apertured plastic films, and fiber-entangled apertured films; hydro-formed thermoplastic films; porous foams; reticulated foams; reticulated thermoplastic films; thermoplastic scrims; or combinations thereof. Some suitable examples of films that can be utilized as topsheets are described in U.S. Pat. Nos. 3,929,135; 4,324,246; 4,342,314; 4,463,045; 5,006,394; 4,609,518; and 4,629,643.
Nonlimiting examples of woven and nonwoven web materials that may be suitable for use as the topsheet include fibrous materials made from natural fibers, modified natural fibers, synthetic fibers, or combinations thereof. Some suitable examples are described in U.S. Pat. Nos. 4,950,264, 4,988,344; 4,988,345; 3,978,185; 7,785,690; 7,838,099; 5,792,404; and 5,665,452.
In some examples, the topsheet may comprise tufts as described in U.S. Pat. Nos. 8,728,049; 7,553,532; 7,172,801; 8,440,286; 7,648,752; and 7,410,683. The topsheet may have a pattern of discrete hair-like fibrils as described in U.S. Pat. No. 7,655,176 or U.S. Pat. No. 7,402,723. Additional examples of suitable topsheet materials include those described in U.S. Pat. Nos. 8,614,365; 8,704,036; 6,025,535 and US 2015/041640. Another suitable topsheet may be formed from a three-dimensional substrate as detailed in US 2017/0258647. The topsheet may have one or more layers, as described in US 2016/0167334; US 2016/0166443; and US 2017/0258651. The topsheet may be apertured, as described in U.S. Pat. No. 5,628,097.
As contemplated herein, component nonwoven web material from which topsheet 30 be cut may be a nonwoven web material that includes or consists predominately (by weight) or entirely of cellulosic plant fibers such as fibers of cotton, flax, hemp, jute or mixtures thereof, that are either naturally hydrophilic or suitably processed so as be rendered hydrophilic (or have increased hydrophilicity) and processed to be suitably soft. Plant-based fibers may be preferred to appeal to consumer preferences for natural products. In other examples, semisynthetic fibers derived from cellulosic material, such as rayon (including viscose, lyocell, MODAL (a product of Lenzing AG, Lenzing, Austria) and cuprammonium rayon) may be used. In some examples a topsheet cut from a carded nonwoven including or consisting predominately (by weight) or entirely of cotton fibers may be preferred. In some examples, the nonwoven web material may be formed via a carding process. In some other examples the nonwoven web material may be formed in a co-forming process in which plant-based fibers of finite lengths are physically blended or mixed with streams of filaments of indefinite lengths, spun from polymeric resin, and laid down on a forming belt to form a web as described in, for example, U.S. Pat. Nos. 8,017,534; 4,100,324; US 2003/0200991; U.S. Pat. No. 5,508,102; US 2003/0211802; EP 0 333 228; WO 2009/10938; US 2017/0000695; US 2017/0002486; U.S. Pat. No. 9,944,047; 2017/0022643 and US 2018/0002848.
For purposes of limiting bulk and caliper (thickness) of the pad, it may be desired that the topsheet be disposed in direct face-to-face relationship with the absorbent layer, with no intervening layer disposed therebetween. Alternatively, the pad may comprise an intervening layer, such as a secondary topsheet and/or an acquisition layer, positioned between the topsheet and the absorbent core. The secondary topsheet and/or an acquisition layer may be formed of a nonwoven web material, such as a spunlace nonwoven. Suitable spunlace nonwovens are discussed in additional detail in U.S. Patent Publication No. 2015/0351976. In some forms, the secondary topsheet may comprise superabsorbent similar to the superabsorbent in the absorbent core or different than the absorbent core. The secondary topsheet may comprise a first end and an opposing second end and a pair of longitudinally opposing side edges and connecting the first end and the second end. The secondary topsheet may be asymmetrical or symmetrical about the longitudinal centerline.
Any suitable absorbent layer/core known in the art may be utilized. The absorbent layer/core may be any absorbent member which is generally compressible, conformable, non-irritating to the wearer's skin, and capable of absorbing and retaining liquids such as urine, menses, and/or other body exudates. The absorbent layer/core may be manufactured from a wide variety of liquid-absorbent materials commonly used in disposable absorbent articles, such as comminuted wood pulp (generally referred to as airfelt). The absorbent layer/core may comprise superabsorbent polymers (SAP) and less than 15%, less than 10%, less than 5%, less than 3%, or less than 1% of airfelt, or be completely free of airfelt. Examples of other suitable absorbent materials comprise creped cellulose wadding, meltblown polymers including coform, chemically stiffened, modified or cross-linked cellulosic fibers, tissue including tissue wraps and tissue laminates, absorbent foams, absorbent sponges, superabsorbent polymers, absorbent gelling materials, or any equivalent material or combinations of materials.
The configuration and construction of the absorbent layer/core may vary (e.g., the absorbent core may have varying caliper zones, a hydrophilic gradient, a superabsorbent gradient, or lower average density and lower average basis weight acquisition zones; or may comprise one or more layers or structures). In some forms, the absorbent layer/core may comprise one or more channels, such as two, three, four, five, or six channels.
The absorbent layer/core of the present disclosure may comprise one or more adhesives, for example, to help immobilize the SAP or other absorbent materials within a core wrap and/or to ensure integrity of the core wrap, in particular when the core wrap is made of two or more substrates. The core wrap may extend to a larger area than required for containing the absorbent material(s) within.
Absorbent layers/cores comprising relatively high amounts of SAP with various core designs are disclosed in U.S. Pat. No. 5,599,335 to Goldman et al., EP 1,447,066 to Busam et al., WO 95/11652 to Tanzer et al., U.S. Pat. Publ. No. 2008/0312622A1 to Hundorf et al., and WO 2012/052172 to Van Malderen.
Other forms and more details regarding channels and pockets that are free of, or substantially free of absorbent materials, such as SAP, within absorbent cores are discussed in greater detail in U.S. Patent Application Publication Nos. 2014/0163500, 2014/0163506, and 2014/0163511, all published on Jun. 12, 2014.
Other suitable materials for use in absorbent layers/cores comprise open celled foams or pieces thereof. The use of foams in absorbent cores is described in additional detail in U.S. Pat. Nos. 6,410,820; 6,107,356; 6,204,298; 6,207,724; 6,444,716; 8,211,078, and 8,702,668.
In some forms, the absorbent layer/core structure may comprise a heterogeneous mass layer or may utilize methods or parameters such as those described in U.S. patent application Ser. No. 14/715,984, filed May 19, 2015; U.S. patent application Ser. No. 14/750,399, Jun. 25, 2015; U.S. patent application Ser. No. 14/751,969 filed Jun. 26, 2015; U.S. patent application Ser. No. 15/078,132 filed Mar. 23, 2016; U.S. patent application Ser. No. 14/750,596 filed Jun. 25, 2015; U.S. patent application Ser. No. 15/084,902 filed Mar. 30, 2016; U.S. patent application Ser. No. 15/343,989 filed Nov. 4, 2016; U.S. patent application Ser. No. 15/344,273 filed Nov. 4, 2016; U.S. patent application Ser. No. 15/344,294 filed Nov. 4, 2016; U.S. patent application Ser. No. 14/704,110 filed May 5, 2015; U.S. patent application Ser. No. 15/194,894 filed Jun. 28, 2016; U.S. patent application Ser. No. 15/344,050 filed Nov. 4, 2016; U.S. patent application Ser. No. 15/344,117 filed Nov. 4, 2016; U.S. patent application Ser. No. 15/344,177 filed Nov. 4, 2016; U.S. patent application Ser. No. 15/344,198 filed Nov. 4, 2016; U.S. patent application Ser. No. 15/344,221 filed Nov. 4, 2016; U.S. patent application Ser. No. 15/344,239 filed Nov. 4, 2016; U.S. patent application Ser. No. 15/344,255 filed Nov. 4, 2016; U.S. patent application Ser. No. 15/464,733 filed Nov. 4, 2016; U.S. Provisional Patent Application No. 62/437,208 filed Dec. 21, 2016; U.S. Provisional Patent Application No. 62/437,225 filed Dec. 21, 2016; U.S. Provisional Patent Application No. 62/437,241 filed Dec. 21, 2016; or U.S. Provisional Patent Application No. 62/437,259 filed Dec. 21, 2016. The heterogeneous mass layer has a depth, a width, and a height.
In some forms, a combination of absorbent layer/core materials may be utilized. For example, forms are contemplated where a first layer of an absorbent core comprises a foam material or pieces thereof, as previously described, and a second layer of an absorbent core comprises an airlaid material. Such combinations are described in U.S. Patent Publication No. 2014/0336606 and U.S. Pat. No. 9,649,228.
The backsheet 40 may be positioned adjacent an outward-facing surface of the absorbent layer/core 50 and may be joined thereto by any suitable attachment methods. For example, the backsheet 40 may be secured to the absorbent layer 50 by a uniform continuous layer of adhesive, a patterned layer of adhesive, or an array of separate lines, spirals, or spots of adhesive. Illustrative, but non-limiting adhesives, include adhesives manufactured by H. B. Fuller Company of St. Paul, Minn., U.S.A., and marketed as HL-1358J. An example of a suitable attachment device including an open pattern network of filaments of adhesive is disclosed in U.S. Pat. No. 4,573,986 entitled “Disposable Waste-Containment Garment”, which issued to Minetola et al. on Mar. 4, 1986. Another suitable attachment device including several lines of adhesive filaments swirled into a spiral pattern is illustrated by the apparatus and methods shown in U.S. Pat. No. 3,911,173 issued to Sprague, Jr. on Oct. 7, 1975; U.S. Pat. No. 4,785,996 issued to Ziecker, et al. on Nov. 22, 1978; and U.S. Pat. No. 4,842,666 issued to Werenicz on Jun. 27, 1989. Alternatively, the attachment method may include heat bonds, pressure bonds, ultrasonic bonds, dynamic mechanical bonds, or any other suitable attachment mechanisms or combinations thereof. In other examples, it is contemplated that the absorbent layer 50 is not joined directly to the backsheet 40. The topsheet 30 may be joined to the backsheet 40 by the attachment methods described above. The topsheet and the backsheet may be joined directly to each other in the pad periphery and/or may be indirectly joined together by directly joining each to the absorbent core 50 by any suitable attachment method.
The backsheet 40 may be impervious, or substantially impervious, to liquids (e.g., urine, menstrual fluid) and may be manufactured from a thin plastic film, although other flexible liquid impervious materials may also be used. As used herein, the term “flexible” refers to materials which are compliant and will readily conform to the general shape and contours of the human body. The backsheet 40 may prevent, or at least substantially inhibit, fluids absorbed and contained within the absorbent layer 50 from escaping and reaching articles of the wearer's clothing which may contact the pad 20, such as underpants and outer clothing. However, in some instances, the backsheet 40 may be made and/or adapted to permit vapor to escape from the absorbent layer 50 (i.e., the backsheet may be made to be breathable), while in other instances the backsheet 40 may be made so as not to permit vapors to escape (i.e., it may be made to be non-breathable). Thus, the backsheet 40 may comprise a polymeric film such as thermoplastic films of polyethylene or polypropylene. A suitable material for the backsheet 40 is a thermoplastic film having a thickness of from about 0.012 mm (0.5 mil) to about 0.051 mm (2.0 mils), for example. Any suitable backsheet known in the art may be utilized with the present invention.
Some suitable examples of backsheets are described in U.S. Pat. Nos. 5,885,265; 4,342,314; and 4,463,045. Suitable single layer breathable backsheets for use herein include those described for example in GB A 2184 389; GB A 2184 390; GB A 2184 391; U.S. Pat. Nos. 4,591,523, 3,989,867, 3,156,242; WO 97/24097; U.S. Pat. Nos. 6,623,464; 6,664,439 and 6,436,508.
The backsheet may have two layers: a first layer comprising a vapor permeable aperture-formed film layer and a second layer comprising a breathable microporous film layer, as described in U.S. Pat. No. 6,462,251. Other suitable examples of dual or multi-layer breathable backsheets for use herein include those described in U.S. Pat. Nos. 3,881,489, 4,341,216, 4,713,068, 4,818,600; EP 203 821, EP 710 471; EP 710 472, and EP 0 793 952.
The absorbent pads disclosed herein are individually packaged in wrappers. The wrappers comprise materials, preferably sheet materials, comprising natural fibers. Conventional wrappers are manufactured from a thin flexible material, which may be liquid impermeable. For example, conventional wrappers may be made from plastic films or nonwoven webs. The film or nonwoven web may be coated on an inner surface (surface facing the feminine hygiene pad) with a release agent, such as a silicone release agent, providing a releasably attached protective wrapper for the pad to protect the adhesive 70 prior to use, as shown in
The wrappers according to the present disclosure may comprise, consist essentially of, or consist of paper, where the term “paper” refers to a material manufactured in sheets from the pulp of wood or other fibrous substances and may comprise additives, such as synthetic fibers or biodegradable fibers. A wrapper comprising paper, such as Kraft paper, creped paper, and creped Kraft paper, may be recyclable, compostable, and/or biodegradable. In fact, existing recycling infrastructure may be better positioned to accept and process used creped paper than used plastic.
The paper may be Kraft paper, where “Kraft paper” refers to a paper produced from wood pulp by the Kraft process. The Kraft process removes almost all lignin from the wood, which results in almost pure cellulose fibers. The Kraft process is known in the art. A Kraft paper sheet is characterized by overall good strength properties and high porosity, and is thus suitable for a variety of applications.
The paper may comprise a blend of hardwood and softwood fibers, preferably a majority of softwood fibers, which may provide the toughness needed for surviving the creping process and for maintaining sufficient strength and bonding integrity within the fibers. The paper may comprise about 50% by weight to about 80% by weight of softwood fibers. The paper may comprise about 20% by weight to about 50% by weight of hardwood fibers. The hardwood fibers may be selected from the group consisting of maple, oak, elm, birch, poplar, aspen or eucalyptus fibers, and combinations thereof, preferably birch fibers. The softwood fibers may be selected from the group consisting of pines, firs, spruces, hemlocks, larch, and combinations thereof, preferably northern pine fibers. The paper may contain other natural fibers from plants such as cotton, flax, bamboo, wheat straw, red algae and/or other seaweeds, and hemp. The paper may also contain recycled fibers. Preferably, the presence of other natural fibers and/or recycled fibers do not impact the recyclability of the paper. The fibers used in the paper may have a Canadian Standard Freeness of at least 200 mL, more specifically at least 300 mL, more specifically still at least 400 mL, and most specifically at least 500 mL.
The paper may have a MD web modulus in the 1%-2% strain range of less than 600 N/cm, preferably less than 450 N/cm to avoid variation of the placement of the wrapper on the pad and variation of the length of the fold in the pad. The paper may have a stretch, calculated as MD stretch at break, of at least 9%, most preferably 15% or more.
The paper may have a basis weight of about 30 gsm to about 70 gsm, preferably from about 40 gsm to about 70 gsm, more preferably about 45 gsm to about 65 gsm, as determined via test method ISO 536-Basis Weight as modified herein. Paper having lower basis weights, e.g., basis weights less than 30 gsm, may not be sufficiently opaque, based on consumer preferences.
The paper may have a water penetration time of at least 10 seconds, more preferably at least 17 seconds, according to test method EN 868-2:2017 EN ISO 1924-2. Because the absorbent products of the present disclosure may inadvertently come in contact with water or moisture, the wrappers of the present disclosure preferably exhibit some water repellency, to keep moisture and water from contaminating the absorbent pad inside the wrapper. Water repellency may be imparted or enhanced by the presence of lignin, a hydrophobic, high molecular weight natural polymer found in wood, wax, or a sizing agent in or on the paper. Other hydrophobic components may be formulated into a water-based varnish or a primer, which are applied to the surface of the paper. Preferably, any hydrophobic coating on the paper is applied in a minimal amount and does not impact the recyclability of the wrapper comprising the paper.
In some embodiments, a small amount of lignin may remain in the pulp, after the pulping process, to provide some hydrophobicity. To increase the hydrophobicity, lignin may also be coated onto paper using various methods.
In some embodiments, wax may be added and/or applied to the paper to increase the hydrophobicity. Waxes include emulsions of natural waxes, such as carnauba wax. beeswax, candelilla wax, rice bran wax, soybean wax, as well as petroleum-based waxes, such as paraffin wax, montanwax, and food grade synthetic waxes, such as oxidized LDPE and HDPE. Wax emulsions may be added to the pulp or a small coating of wax may be applied on the surface of the paper. The wax may be applied prior to subsequent processing, such as creping.
In some embodiments, sizing agents may be added and/or applied to the paper to increase the hydrophobicity. Sizing agents include internal sizing agents, which are added to the pulp during the production of the paper, and surface sizing agents, which are coated onto paper. Internal sizing agents include acidic type internal sizing agents, such as rosin and rosin derivatives, which contain aluminum resinate and are derived from natural resins and aluminum salts. Basic and neutral type internal sizing agents include synthetic sizing agents, such as alkylated ketene dimers (stable, hydrophobic waxy substances) and alkenyl succinic anhydrides (reactive, hydrophobic oily substances). Surface sizing agents include modified starches and gelatin, which can be naturally derived, as well as synthetic agents, such as styrenic polymers (e.g., styrene maleic anhydride, styrene acrylic emulsions, styrene acrylic acid, ethylene acrylinc acid, and polyurethane).
As previously discussed, paper wrappers are intended to be an alternative to traditional polymeric wrappers. However, for a paper wrapper to be a viable alternative, the paper needs to have properties that allow it to withstand the relatively rigorous manufacturing process and to adequately protect the absorbent article to be housed within the wrapper. One of the ways to enhance the properties of paper is to crepe the paper. “Creping” is a mechanical process for creating a low density, and increased caliper, paper (“crepe paper”).
Completed crepes are constantly moving away from the crepe pocket as the sheet 200 is wound up onto the parent roll 108. The crepe process shortens the length of the sheet 200 while increasing its caliper, thus the reel winding the parent roll 108 runs slower than the Yankee cylinder 102. The sheet caliper in expanded first by x-direction hydrogen bond disruption and secondly by the crepe action. However, the crepe itself is not necessarily uniform. The crepe may consist of large folds (macrofolds, as shown in Stage 4) interspersed with many smaller folds (microfolds, as shown in Stage 3).
The crepe bars in crepe paper make the crepe paper stretchable, at least in the longitudinal direction, and after being stretched, the crepe paper may remain somewhat clastic. Creped paper is generally more elastic than paper that has not been subjected to a creping process. Thus, stretchability and elasticity make crepe paper a suitable replacement for plastic, in the context of wrappers for absorbent pads. Preferably, the absorbent pad may be wrapped in the crepe paper wrapper on a high-speed production line, using essentially the same process and equipment as is used for current absorbent pads wrapped in plastic film. In other words, it would be desirable to provide such an article (e.g., pad) without compromising process conditions, such as, for example, the line speed.
Processes for manufacturing individually packaged, folded feminine hygiene articles are known in the art and described in, for example, European Patent Application No. 1941852A1.
Generally, in existing high speed production lines, the material of the wrapper 80 is typically provided in a continuous web. The adhesive 70 disposed on the outward-facing surface of the backsheet 40 of the absorbent pad (as shown in
The wrapper material may be subjected to substantial stress in known high speed processes to produce individually packaged absorbent articles. The stress can be both mechanical and thermal. Thermal stresses may be due, at least in part, to the adhesive material that is typically a hot melt adhesive being disposed on the wrapper material in molten state, which is at relatively high temperature. Mechanical stresses may be due, at least in part, to the tension and forces placed on the wrapper during the manufacturing process. For many years, the absorbent feminine hygiene industry has been investing in manufacturing equipment designed to run plastic wrapper materials while achieving high throughput, accuracy, efficiency, and low cost production, using highly optimized materials and processes. On the contrary, the paper used in the manufacture of conventional paper sacks, for example, is processed on equipment designed specifically for converting paper and is converted at speeds that are considerably slower than the speeds used in the production of absorbent hygiene products (converting speeds for absorbent hygiene products may exceed 100 meters/min). Also, conventional Kraft papers (used in, for example, packaging or label release liners) are not sufficiently stretchable to survive the wrapper folding, transporting, and sealing operations that are typically used in the production of absorbent hygiene products without wrinkling, tearing, or having web slack, which results in productivity losses, increased scrap, and generally low quality wrapping.
Furthermore, most existing folding processes involve some stretching of the wrapper web. Generally, to fold the wrapper a folding surface (such as fingers, bars, rollers, idlers, folding boards etc.) may be used to apply a force to the wrapper and create one or more fold lines. It is to be appreciated that any folding surface may be replaced by one or more elements, objects, or media, used to apply forces to create a similar or same folding of the web. Some existing folding processes rely on equal folding path lengths between a first edge of a wrapper web and a second edge of the wrapper web, which runs over an idler to force a folding line. This process may be used to make two or more folds in the wrapper, where the number of folds is generally related to the desired height of the wrapped pad. Alternatively, the folding process may utilize one or more folding boards to fold the wrapper web and the pad. As noted above, most existing folding processes involve some stretching of the wrapper web, and conventional Kraft papers may be prone to tearing in these processes due to their lack of stretch.
Conventional Kraft paper is characterized by a stretch of less than 5%, where stretch is measured as the percent strain of the paper at its breaking point, stretch is calculated as the MD stretch at break. As previously discussed, paper may be creped to add stretch or paper may be selected that has an ability to stretch based on its material properties. With regard to creped paper, the increase in stretch is believed to be due to the microfolds in the creped paper, which may stretch out under tension. The paper wrapper according to the present disclosure preferably comprises a paper, such as a creped paper, having a stretch of at least 9%, preferably at least 10% or greater, or at least 17% or greater, in order to withstand the existing folding processes.
Some folding processes, such as those that utilize equal fold path lengths and idlers to force folding lines, may require a wrapper web to have a folding angle of at least about 45°, or from about 45° to about 90°, or preferably from about 45° to about 65°. The folding angle is related to the bending stiffness of the wrapper web in the folding direction and the caliper of the wrapper web by the following equation:
where the density of the wrapper web is calculated by measuring the basis weight of the paper in Kilogram per square meter, following the ISO 536 test method described herein, and dividing the measured basis weight by the measured paper thickness in meters, which is measured using a Thwing-Albert ProGauge Instrument, with a 50.8 mm diameter foot and 2.00 kPa pressure, and where the bending modulus is calculated as (0.3125*slope)/(compressed caliper{circumflex over ( )}3) and expressed in MegaPascals, where compressed caliper measurements are obtained using a TMI 49-70 high force caliper with a 16 mm anvil and 50.40 kPa pressure and the slope is obtained using the Ultra Sensitive 3 point Bending Method, described below. The folding width is the distance between the folding line and the edge of the paper expressed in meters. Generally, a material having a high bending stiffness and a high compressed caliper will be characterized by a lower folding angle, which makes the material more difficult to fold, particularly in a folding process that utilizes equal folding path lengths and idlers to force folding lines.
As discussed above, the wrapper of the present disclosure functions to protect the absorbent article and, more specifically, in some embodiments, the adhesive 70 on the outward-facing surface of the backsheet 40 of the absorbent pad 20, as shown in
The release agent 90 may be applied to the wrapper at an amount of about 0.5 g/m2 to about 10 g/m2, or from about 1.0 g/m2 to about 6 g/m2, or from about 1.0 g/m2 to about 4 g/m2, or from about 2 g/m2 to about 4 g/m2. The amount of release agent 90 will depend on the type, concentration, and effectiveness of the compound aiding the release in the release agent coating formula. As shown in
The wrapper also protects the absorbent pad by sealing the absorbent pad within the wrapper. In order to seal the wrapper of the present disclosure, e.g., paper wrapper, using existing equipment designed to convert plastic film wrapper (the sealing equipment widely used today relies on heat and pressure to bond the plastic film), the wrapper may be coated with a sealing aid. The sealing aid 95 is applied to a portion or a region of the wrapper's surface that need to be sealed to another portion or region of the wrapper's surface. For example, as illustrated in
Sealing aids include cold- and heat-seal adhesives. Heat-seal adhesives are preferred. Scaling aids also include water-based adhesives containing acrylic copolymers, vinyl acetate polymers, or blends thereof with low density polyethylene or high density polyethylene. Preferred sealing aids, such as heat seal adhesives, are also water-soluble to avoid contamination in recycling streams. The preferred sealing aids, such as heat seal adhesives, also have viscosities between 30s and 60s, measured using ASTM D1084 with Zahn EZ #3 cup, where a sample is taken from the reservoir as the adhesive is coated onto the paper. Sealing aids with higher viscosities may contribute to uneven application, inconsistent wrapper opening forces, and difficult and/or noisy opening of the wrapper.
Sealing aids generally do not adhere to surfaces coated with a release agent. Therefore, as discussed above, the release agent is preferably applied to a targeted region of the wrapper's inner surface, namely the region of the wrapper's inner surface that contacts the adhesive 70 on the pad and, optionally, slightly beyond this region. Preferably, the inner surfaces of the longitudinal side edges of the wrapper, wherein the sealing aid is applied, are substantially free of release agent. Importantly, targeting a release agent, particularly a curable silicone release agent, to a region of the wrapper requires specialized application and curing equipment.
Surprisingly, the wrapper according to the present disclosure may utilize a release agent that can be applied using readily available and installable printing equipment, such as flexographic and gravure printing presses. More specifically, the preferred release agents for use with the wrappers according to the present disclosure are substantially free of or free of silicone acrylates, cationic curable silicones, and/or polydimethylsiloxanes, which require nitrogen inerting equipment, ultraviolet lights, or other specialty equipment and may contaminate recycling streams. The release agent may also be substantially free of or free of fluoropolymers. The release agent may comprise an aliphatic modified polyurethane dispersion, a hydrophobic acrylic polymer, a vinyl acrylic copolymer, or a mixture thereof. Bio-based acrylic polymers and other biomass-derived polymers, made from renewable feedstocks like vegetable oils and cellulose, may also be used in the formulation of the release agent.
The release agent may contain natural substances that can provide release by mechanism of electrochemical interactions. Some of these substances are used in the food industry as release agents and may be derived from lecithin, vegetable oil, or animal fat. The release agent may also contain particles, such as clays, silica, and/or ceramics (e.g., hexagonal boron nitride or zinc stearate) to further improve release by increasing the rugosity of the applied-to surface, by dipole electrochemical interactions, or by molecular planar slip. Preferably, the release agent is a water-based and water-soluble formula, which can be easily removed in available paper recycling streams.
Furthermore, paper tends to be porous, and paper that has undergone creping can be even more porous. Thus, coating that are applied to the paper may be absorbed through the pores of the paper, which may reduce the efficacy of the coating or require a greater amount of the coating to be applied. To increase the efficacy of the coating and to minimize the amount of coating, a primer may be applied to the surface of the paper to reduce the porosity of the paper by reducing the size of the pores in the paper. Primers may also improve the appearance of printed graphics, maintaining the definition of lines and reducing dot gains. The preferred primers are water-based and/or water soluble. The primer may be formulated with polymer resins, such as nitrocellulose, polyamides, acrylic polymers, polyurethanes, and adhesion promoters, such as polyimides, silanes, and aziridine. The primer formulation may also comprise biobased polymers, such as cellulose, starch, chitin, chitosan, xylan, other types of hemicelluloses, and polyesters derived from vegetable oils. The primer formulation may also contain minerals, such as clays, silicas, talc, and calcium carbonate (sometimes referred to as inorganic fillers). The use of primers may be particularly useful for creped paper due to the relatively greater porosity of the paper having been creped. The primer may be used to reduce the porosity of the creped paper by reducing the size of the pores in the paper.
The coatings as discussed herein may be applied to the paper wrapper in various configurations depending on, at least in part, the type of paper, configuration of the fold, and areas of the wrapper to be sealed. In some embodiments, such as illustrated in the cross sectional view of the wrapper 80 in
Still referring to
It is also to be appreciated that ink may be applied to the wrapper to form one or more decorative patterns or elements. The ink may be disposed directly on the inner or outer surface of the wrapper. The ink may be disposed on the primer and/or the sealing aid and/or the release coating. In some embodiments, the ink may be disposed on the primer so that the pores of the wrapper become smaller and less ink needs to be applied to get the same visual intensity because the ink does not get absorbed into the pores of the wrapper.
As previously discussed, the placement of the sealing aid 95 may be in regions of the wrapper 80 such that when the wrapper is in a folded configuration, the sealing aid 95 is placed in regions of the wrapper that will be sealed together. Those portions of the wrapper that are sealed together may be sealed by one or more techniques such as ultrasonic bonding, pressure bonding, crimping, and/or thermal bonding. As illustrated in
The wrapper of an absorbent pad is preferably easy to open and convenient to use, and the seal of the wrapper is preferably strong enough to survive transport, e.g., inside a purse or a bag. Preferably, the sealing aid creates bonds that open with a force of greater than about 0.5 N and less than about 3.0 N, preferably a force of about 1.0 N to about 2.0 N. The strength of the bonds is measured using a testing machine conforming to ASTM D76-93 standard for constant rate of extension and follow ASTM D1876-08 using a test speed of 300 mm/min and peeling the bond open in the direction perpendicular to the seal in a way that the test length will be equal to the width of the seal. The values expressed above represent the Peak Force recorded over the test length.
For quiet and easy release of the pad from the wrapper, the release peel force of the pad from the inner surface of the wrapper (coated with the release agent) is less than about 5.0 N, or from about 0.5 N to about 3.0 N, preferably less than 3.0 N, and greater than about 1.0 N. The release peel force is measured using a test machine conforming to ASTM D76-93 standard for constant rate of extension, following ASTM D1876-08, loading the pad with the wrapper into the instrument by clamping the wrapper to the movable jaw and the top of the pad to the stationary jaw. The wrapper is peeled from the pad along the long direction of the pad using a test speed of 3000 mm/min.
The wrappers of the present disclosure may be recyclable, to minimize material sent to landfills. There are two known industry standards for the recyclability of paper: The Western Michigan University Recyclability Standard, which is available through the WMU Paper Pilot Plants located in 4651 Campus Dr Kalamazoo MI 49008-5441 USA; and the Papiertechnische Stiftung Test Method PTS-RH 021:2012, which is available thru PTS at Pirnaer Strasse 37, 01809 Heidenau, Germany. As used herein, the term “recyclable” refers to a material that meets a 75% yield of good pulp following the West Michigan University Standard.
The data in Table 1 below is illustrated graphically in
The data in Table 2 below is illustrated graphically in
The basis weight of a test sample is the mass (in grams) per unit area (in square meters) of a single layer of material and is measured in accordance with compendial method ISO 536. The mass of the test sample is cut to a known area, and the mass of the sample is determined using an analytical balance accurate to 0.0001 grams. All measurements are performed in a laboratory maintained at 23° C.±2 C.° and 50%±2% relative humidity and test samples are conditioned in this environment for at least 2 hours prior to testing.
Measurements are made on test samples taken from rolls or sheets of the raw material, or test samples obtained from a finished package. When excising the test sample from a finished package, use care to not impart any contamination or distortion to the sample during the process. The excised sample should be free from residual adhesive and taken from an area of the package that is free from any seams or folds. The test sample must be as large as possible so that any inherent material variability is accounted for.
Measure the dimensions of the single layer test sample using a calibrated steel metal ruler traceable to NIST, or equivalent. Calculate the Area of the test sample and record to the nearest 0.0001 square meter. Use an analytical balance to obtain the Mass of the test sample and record to the nearest 0.0001 gram. Calculate Basis Weight by dividing Mass (in grams) by Area (in square meters) and record to the nearest 0.01 grams per square meter (gsm). In like fashion, repeat for a total of ten replicate test samples. Calculate the arithmetic mean for Basis Weight and report to the nearest 0.01 grams/square meter.
The tensile properties (tensile strength, stretch, and energy absorption) of a test sample are calculated from measured force and elongation values obtained using a constant rate of elongation until the sample breaks. The test is run in accordance with compendial method ISO 1924-3, with modifications noted herein. Measurements are made on a constant rate of extension tensile tester using a load cell for which the forces measured are within 1% to 99% of the limit of the cell. A suitable instrument is the MTS Alliance using Test Suite Software, available from MTS Systems Corp., Eden Prairie, Minn., or equivalent. All measurements are performed in a laboratory maintained at 23° C.±2 C.° and 50%±2% relative humidity and test samples are conditioned in this environment for at least 2 hours prior to testing.
Measurements are made on both MD (machine direction) and CD (cross direction) test samples taken from rolls or sheets of the raw material, or test samples obtained from a finished package. When excising the test sample from a finished package, use care to not impart any contamination or distortion to the sample during the process. The excised sample should be free from residual adhesive and taken from an area of the package that is free from any seams or folds. The test sample is cut to a width of 25.4 mm with a length that can accommodate a test span of 50.8 mm. The long side of the sample is parallel to the direction of interest (MD, CD). Normally in finished packages, the MD runs from the bottom to the top of the package, but this can be verified by determining the fiber orientation if in doubt. Ten replicate test samples should be prepared from the MD and ten additional replicates from the CD.
Program the tensile tester for a constant rate of extension uniaxial elongation to break as follows. Set the gauge length (test span) to 50.8 mm using a calibrated gauge block and zero the crosshead. Insert the test sample into the grips such that the long side is centered and parallel to the central pull axis of the tensile tester. Raise the crosshead at a rate of 508 mm/min until the test sample breaks, collecting force (N) and extension (mm) data at 100 Hz throughout the test. Construct a graph of force (N) versus extension (mm).
Read the maximum force (N) from the graph and record as Peak Force to the nearest 0.1 N, noting MD or CD. Read the extension at the maximum force (N) from the graph and record as Elongation at Break to the nearest 0.01 mm, noting MD or CD.
Calculate the arithmetic mean Peak Force for all MD replicates and then all CD replicates and record respectively as Mean MD Peak Force and Mean CD Peak Force to the nearest 0.1 N. Calculate the arithmetic mean Elongation at Break for all MD replicates and then all CD replicates and record respectively as Mean MD Elongation at Break and Mean CD Elongation at Break to the nearest 0.01 mm.
Tensile strength is calculated by dividing the Mean Peak Force (N) by the width of the test sample (25.4 mm). Calculate the tensile strength for the MD replicates and then the CD replicates and report respectively as MD Tensile Strength and CD Tensile Strength to the nearest 0.1 kN/m.
Stretch at break is calculated by dividing the Mean Elongation at Break (mm) by the initial test length (test span) of 50.8 mm, and then multiplying by 100. Calculate the stretch at break for the MD replicates and then the CD replicates and report respectively as MD Stretch at Break and CD Stretch at Break to the nearest percent.
Web Modulus in MD: Take the force data (N) and divide by the width of the specimen, which in this case is 2.54 cm to obtain Force per cm. Take the extension data (mm), divide by the initial test length of 50.8 mm to obtain the strain (mm/mm). Construct a graph of Force per mm by strain. Calculate the slope of the curve between the 1%-2%, 2%-3%, 3%-4% and 4%-5% strain intervals and report the results in N/cm.
The bending properties of a test sample are measured using an Ultra Sensitive 3 Point Bend Test on a universal constant rate of extension test frame (a suitable instrument is the MTS Alliance using TestSuite Software, as available from MTS Systems Corp., Eden Prairie, MN, or equivalent) equipped with a load cell appropriate for the forces being measured. The test is executed on test specimens prepared for both MD (machine direction; parallel to the longitudinal axis of the absorbent article) and CD (cross direction; perpendicular to the longitudinal axis of the absorbent article) bending. All testing is performed in a room controlled at 23° C.±3° C. and 50%±2% relative humidity.
The ultra-sensitive 3 point bend method is designed to maximize the force signal to noise ratio when testing materials with very low bending forces. The force signal is maximized by using a high sensitivity load cell (e.g., 5 N), using a small span (load is proportional to the span cubed) and using a wide specimen width (total measured load is directly proportional to width). The fixture is designed such that the bending measurement is performed in tension, allowing the fixture mass to be kept to a minimum. Noise in the force signal is minimized by holding the load cell stationary to reduce mechanical vibration and inertial effect and by making the mass of the fixture attached to the load cell as low as possible.
Referring to
Absorbent article samples are conditioned at 23° C.±3° C. and 50%±2% relative humidity two hours prior to testing. Test specimens are taken from an area of the sample that is free from any seams and residua of folds or wrinkles. The specimens are prepared by cutting them to dimensions of 100 mm by 50 mm. For MD bending (i.e., bending normal to the longitudinal axis of the article), the long side of the test specimen is parallel to the longitudinal axis of the article. For CD bending (i.e., bending normal to the lateral axis of the article), the long side of specimen is parallel to the lateral axis of the article. The side of the test specimen that faces the surface of the absorbent article (or the side intended to face the surface of a finished article) is marked and the orientation (i.e., MD and CD) is maintained after the specimens are cut. In like fashion, five replicate test specimens are prepared for MD bending and five separate test specimens are prepared for CD bending.
The universal test frame is programmed such that the moveable crosshead is set to move in a direction opposite of the stationary crosshead at a rate of 1.0 mm/s. Crosshead movement begins with the specimen 1006 lying flat and undeflected on the outer blades 1003a and 1003b, continues with the inner horizontal edge of cavity 1005 in the central blade 1002 coming into contact with the surface of the specimen 1006, and further continues for an additional 7 mm of crosshead movement, and then stops to end the test. The crosshead then returns to zero. Force (N) and displacement (mm) are collected at 50 Hz throughout.
Prior to loading the test specimen 1006, the outside blades 1003a and 1003b are moved towards and then past central blade 1002 until there is approximately a 3 mm clearance, c, between the inner horizontal edges of cavities 1004a and 1004b in the outside blades 1003a and 1003b and the inner horizontal edge of cavity 1005 in the central blade 1002 (see
Force (N) is plotted versus displacement (mm). The maximum peak force is recorded to the nearest 0.001 N. The slope of the linear portion of the force versus displacement curve is determined and recorded as slope to the nearest 0.001 N/mm. The area under the curve from load onset up to the maximum peak force is calculated and recorded as energy to peak to the nearest 0.001 N-mm. In like fashion, repeat the entire test sequence for a total of five MD bending test specimens and five CD bending test specimens.
For each test specimen type (MD and CD), the arithmetic mean of the maximum peak force among like specimens is calculated to the nearest 0.001 N and recorded as MD Peak Load and CD Peak load, respectively. For each test specimen type (MD and CD), the arithmetic mean of the slope among like specimens is calculated to the nearest 0.001 N/mm and reported as MD Slope and CD Slope, respectively. For each test specimen type (MD and CD), the arithmetic mean of the energy to peak among like specimens is calculated to the nearest 0.001 N-mm and reported as MD Energy to Peak and CD Energy to Peak, respectively.
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.”
Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, 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 claim priority under 25 USC § 119(c), to U.S. Provisional Patent Application Ser. No. 63/453,569, filed on Mar. 21, 2023.
| Number | Date | Country | |
|---|---|---|---|
| 63453569 | Mar 2023 | US |
