WO2023033796A1 - Topsheet layer for an absorbent article - Google Patents
Topsheet layer for an absorbent article Download PDFInfo
- Publication number
- WO2023033796A1 WO2023033796A1 PCT/US2021/048347 US2021048347W WO2023033796A1 WO 2023033796 A1 WO2023033796 A1 WO 2023033796A1 US 2021048347 W US2021048347 W US 2021048347W WO 2023033796 A1 WO2023033796 A1 WO 2023033796A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- topsheet layer
- layer
- fibers
- absorbent article
- topsheet
- Prior art date
Links
- 230000002745 absorbent Effects 0.000 title claims abstract description 84
- 239000002250 absorbent Substances 0.000 title claims abstract description 84
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- 238000000034 method Methods 0.000 claims description 40
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 27
- 230000002209 hydrophobic effect Effects 0.000 claims description 24
- 238000009991 scouring Methods 0.000 claims description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- 238000009835 boiling Methods 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 239000007788 liquid Substances 0.000 abstract description 23
- 230000009467 reduction Effects 0.000 abstract description 5
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- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 2
- 235000017166 Bambusa arundinacea Nutrition 0.000 description 2
- 235000017491 Bambusa tulda Nutrition 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
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- MJBPUQUGJNAPAZ-AWEZNQCLSA-N Butin Natural products C1([C@@H]2CC(=O)C3=CC=C(C=C3O2)O)=CC=C(O)C(O)=C1 MJBPUQUGJNAPAZ-AWEZNQCLSA-N 0.000 description 1
- MJBPUQUGJNAPAZ-UHFFFAOYSA-N Butine Natural products O1C2=CC(O)=CC=C2C(=O)CC1C1=CC=C(O)C(O)=C1 MJBPUQUGJNAPAZ-UHFFFAOYSA-N 0.000 description 1
- 244000025254 Cannabis sativa Species 0.000 description 1
- 235000012766 Cannabis sativa ssp. sativa var. sativa Nutrition 0.000 description 1
- 235000012765 Cannabis sativa ssp. sativa var. spontanea Nutrition 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
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- 229920000161 Locust bean gum Polymers 0.000 description 1
- 240000003433 Miscanthus floridulus Species 0.000 description 1
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- QYKIQEUNHZKYBP-UHFFFAOYSA-N Vinyl ether Chemical class C=COC=C QYKIQEUNHZKYBP-UHFFFAOYSA-N 0.000 description 1
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- 239000000017 hydrogel Substances 0.000 description 1
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- 235000010977 hydroxypropyl cellulose Nutrition 0.000 description 1
- 239000003999 initiator Substances 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 239000004816 latex Substances 0.000 description 1
- 229920000126 latex Polymers 0.000 description 1
- 239000000711 locust bean gum Substances 0.000 description 1
- 235000010420 locust bean gum Nutrition 0.000 description 1
- 239000006210 lotion Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229920000609 methyl cellulose Polymers 0.000 description 1
- 239000001923 methylcellulose Substances 0.000 description 1
- 235000010981 methylcellulose Nutrition 0.000 description 1
- 229920001206 natural gum Polymers 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 239000002964 rayon Substances 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 description 1
- 239000011122 softwood Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 235000000346 sugar Nutrition 0.000 description 1
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- 239000004583 superabsorbent polymers (SAPs) Substances 0.000 description 1
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/51—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the outer layers
- A61F13/511—Topsheet, i.e. the permeable cover or layer facing the skin
- A61F13/51121—Topsheet, i.e. the permeable cover or layer facing the skin characterised by the material
-
- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
- D04H1/425—Cellulose series
Definitions
- Products such as absorbent articles are often used to collect and retain human body exudates containing, for example, urine, menses and/or blood.
- Comfort, absorbency, and discretion are three main product attributes and areas of concern for the wearer of the product.
- a wearer is often interested in knowing that such products will absorb significant volumes of body exudates with minimal leakage in order to protect their undergarments, outer garments, or bedsheets from staining, and that such products will help them avoid the subsequent embarrassment brought on by such staining.
- topsheet layer often remains wet or at least feels wet for some time throughout the period of use.
- the topsheet layer may frequently be absorbent, being made from hydrophilic construction materials, such as natural fibers. These materials often retain at their surface some noticeable moisture following soiling, thereby creating the uncomfortable wetness sensation during continued use of the product.
- topsheet layers for reduced wetness (and rewet) based on chemical enhancements to the topsheet layer to provide the topsheet layer with hydrophobic properties.
- hydrophobic topsheet layers can help an absorbent product demonstrate an extended feeling of dryness at the skincontacting surface of the product.
- liquid/fluid that is retained in the interior layers of the product may have less of a propensity to pass back through the topsheet layer to the wearer's skin as a result of the hydrophobic interior surface properties of the topsheet layer.
- the topsheet layer acts as a one-way valve allowing moisture to pass in one direction and keeping it below the user-facing, skin-contacting surface.
- such chemically enhanced hydrophobic topsheet layers aren't suitable for a consumer who may have sensitive skin and/or have a preference for absorbent products with a natural topsheet layer.
- an improved product such as an absorbent article, which has an improved feeling of comfort next to the skin of the wearer and has a reduction in the feelings of wetness and rewet without the need for chemical enhancement of the topsheet layer.
- a topsheet layer for use in an absorbent article can have non-chemically enhanced natural fibers.
- the natural fibers are cotton fibers.
- the natural fibers are present in an amount greater than 50% by weight by total weight of the topsheet layer. In various embodiments, the natural fibers are present in an amount greater than 75% by weight by total weight of the topsheet layer.
- the topsheet layer is hydrophobic. In various embodiments, the topsheet layer has a water contact angle from 90° to 150°. In various embodiments, the topsheet layer has a water contact angle from 130° to 140°.
- the topsheet layer has a whiteness index of less than 70.
- an absorbent article can have the topsheet layer described herein, a backsheet layer, and an absorbent core positioned between the topsheet layer and the backsheet layer.
- a method of manufacturing the topsheet layer described herein can have the step of scouring the natural fibers by boiling the natural fibers in a sodium hydroxide solution (0.1 - 10 g/L) for 30 - 240 minutes, at a temperature from 60° - 100°C.
- the scouring of the natural fibers is done by boiling the natural fibers in the sodium hydroxide solution (0.5 - 2.0 g/L), for 120 - 180 minutes, at a temperature from 80° - 90°C.
- the natural fibers are not bleached.
- the present disclosure is generally directed towards an absorbent article which can have an improved feeling of comfort next to the skin of the wearer and a reduction in the feelings of wetness and rewet.
- the absorbent article can have a wearer facing, liquid permeable topsheet layer and a garment facing, liquid impermeable backsheet layer.
- An absorbent core can be positioned between the topsheet layer and the backsheet layer.
- the topsheet layer and the backsheet layer can both extend beyond the outermost peripheral edges of the absorbent core and can be peripherally bonded together, either entirely or partially, using known bonding techniques to form a sealed peripheral region.
- the topsheet layer and the backsheet layer can be bonded together by adhesive bonding, ultrasonic bonding, or any other suitable bonding method known in the art.
- the topsheet layer can be formed from non-chemically enhanced natural fibers.
- absorbent article refers herein to a garment or other end-use personal care absorbent article, including, but not limited to, sanitary napkins, feminine pads, pantiliners, panty shields, incontinence garments, diapers, training pants, youth pants, swim pants, and the like.
- airlaid refers herein to a web manufactured by an airlaying process.
- bundles of small fibers having typical lengths ranging from about 3 to about 52 mm are separated and entrained in an air supply and then deposited onto a forming screen, usually with the assistance of a vacuum supply.
- the randomly deposited fibers are then bonded to one another using, for example, hot air to activate a binder component or a latex adhesive.
- Airlaying is taught in, for example, U.S. Patent No. 4,640,810 to Laursen, et al., which is incorporated herein in its entirety by reference thereto for all purposes.
- the term "bonded” refers herein to the joining, adhering, connecting, attaching, or the like, of two elements. Two elements will be considered bonded together when they are joined, adhered, connected, attached, or the like, directly to one another or indirectly to one another, such as when bonded to an intermediate element.
- the bonding can occur via, for example, adhesive, pressure bonding, thermal bonding, ultrasonic bonding, stitching, suturing, and/or welding.
- the term “bonded carded web” refers herein to webs that are made from staple fibers which are sent through a combing or carding unit which separates or breaks apart and aligns the staple fibers in the machine direction to form a generally machine direction oriented fibrous nonwoven web. This material may be bonded together by methods that can include point bonding, through air bonding, ultrasonic bonding, adhesive bonding, etc.
- hydrophilic refers to surfaces with a water contact angle less than 90°.
- hydrophobic refers to surfaces with the property to repel fluid with a water contact angle from 90° to 150°
- the term "super-hydrophobic” refers to surfaces with a water contact angle greater than 150°.
- machine direction refers to the length of a fabric in the direction in which it is produced, as opposed to a “cross-machine direction” (CD) which refers to the width of a fabric in a direction generally perpendicular to the machine direction.
- meltblown web refers herein to a nonwoven web that is formed by a process in which a molten thermoplastic material is extruded through a plurality of fine, usually circular, die capillaries as molten fibers into converging high velocity gas (e.g., air) streams that attenuate the fibers of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly disbursed meltblown fibers.
- high velocity gas e.g., air
- meltblown fibers may be microfibers that are substantially continuous or discontinuous, generally smaller than 10 microns in diameter, and generally tacky when deposited onto a collecting surface.
- nonwoven fabric or “nonwoven web” refers herein to a web having a structure of individual fibers or threads which are interlaid, but not in an identifiable manner as in a knitted fabric.
- Nonwoven fabrics or webs have been formed from many processes such as, for example, meltblowing processes, spunbonding processes, through-air bonded carded web (also known as BCW and TABCW) processes, etc.
- the basis weight of nonwoven webs may generally vary, such as, from about 5, 10 or 20 gsm to about 120, 125 or 150 gsm.
- spunbond web refers herein to a web containing small diameter substantially continuous fibers.
- the fibers are formed by extruding a molten thermoplastic material from a plurality of fine, usually circular, capillaries of a spinneret with the diameter of the extruded fibers then being rapidly reduced as by, for example, eductive drawing and/or other well-known spunbonding mechanisms.
- the production of spunbond webs is described and illustrated, for example, in U.S. Patent Nos.
- Spunbond fibers are generally not tacky when they are deposited onto a collecting surface. Spunbond fibers may sometimes have diameters less than about 40 microns, and often between about 5 to about 20 microns.
- the terms "superabsorbent polymer,” “superabsorbent” or “SAP” shall be used interchangeably and shall refer to polymers that can absorb and retain extremely large amounts of a liquid relative to their own mass.
- Water absorbing polymers which are classified as hydrogels, which can be cross-linked, absorb aqueous solutions through hydrogen bonding and other polar forces with water molecules.
- a SAP's ability to absorb water is based in part on ionicity (a factor of the ionic concentration of the aqueous solution), and the SAP functional polar groups that have an affinity for water.
- SAP are typically made from the polymerization of acrylic acid blended with sodium hydroxide in the presence of an initiator to form a poly-acrylic acid sodium salt (sometimes referred to as sodium polyacrylate).
- Other materials are also used to make a superabsorbent polymer, such as polyacrylamide copolymer, ethylene maleic anhydride copolymer, cross-linked carboxymethylcellulose, polyvinyl alcohol copolymers, cross-linked polyethylene oxide, and starch grafted copolymer of polyacrylonitrile.
- SAP may be present in absorbent articles in particle or fibrous form or as a coating on another material or fiber.
- the present disclosure is generally directed towards an absorbent article which can have an improved feeling of comfort next to the skin of the wearer and a reduction in the feelings of wetness and rewet.
- the absorbent article can have a wearer facing, liquid permeable topsheet layer and a garment facing, liquid impermeable backsheet layer.
- An absorbent core can be positioned between the topsheet layer and the backsheet layer.
- the topsheet layer and the backsheet layer can both extend beyond the outermost peripheral edges of the absorbent core and can be peripherally bonded together, either entirely or partially, using known bonding techniques to form a sealed peripheral region.
- the topsheet layer and the backsheet layer can be bonded together by adhesive bonding, ultrasonic bonding, or any other suitable bonding method known in the art.
- the topsheet layer can be formed from non-chemically enhanced natural fibers. Topsheet Layer:
- the topsheet layer defines a wearer facing surface of the absorbent article that may directly contact the body of the wearer and is liquid permeable to receive body exudates.
- the topsheet layer is desirably provided for comfort and conformability and functions to direct body exudates away from the body of the wearer, through its own structure, and towards the absorbent core.
- the topsheet layer desirably retains little to no liquid in its structure, so that it provides a relatively comfortable and nonirritating surface next to the skin of the wearer of the absorbent article.
- the topsheet layer can be constructed of any woven or nonwoven sheet material which is easily penetrated by bodily exudates which may contact the body-facing surface of the topsheet layer.
- the topsheet layer can be constructed from various nonwoven webs such as, for example, hydroentangled spunlace webs or through air bonded carded webs.
- the topsheet layer can be constructed of natural fibers.
- suitable natural fibers can include, but are not limited to, cotton fibers, rayon fibers, wheat straw fibers, rice straw fibers, flax fibers, bamboo fibers, jute fibers, hemp fibers, sisal fibers, bagasse fibers, hesperaloe fibers, miscanthus, marine or freshwater algae/seaweeds, and combinations thereof.
- the natural fibers can be cotton fibers, bamboo fibers, or combinations thereof.
- the natural fibers can be cotton fibers.
- the topsheet layer has at least 50, 60, 75, 95, 99, or 100% by weight of natural fibers by total weight of the topsheet layer.
- the topsheet layer has at least 75, 95, 99, or 100% by weight of natural fibers by total weight of the topsheet layer. In various embodiments, the topsheet layer has at least 95, 99, or 100% by weight of natural fibers by total weight of the topsheet layer.
- Natural fibers which are still in their raw form are hydrophobic.
- Typical purification steps include ginning, carding, combing, scouring, and bleaching.
- ginning is the first step in purifying raw cotton and separating the cotton lint from the cotton seed and other foreign matter debris (e.g., plant stalk, plant stem, and plant leaves). The cotton lint then undergoes carding to remove tangles within the cotton lint, individualize and align the cotton fibers within the cotton lint, and remove foreign matter debris that passed through the ginning step.
- the carded cotton fibers proceed through a combing step in which any final remaining foreign matter debris is removed, and the cotton fibers are smoothed. Following ginning, carding, and combing, the cotton fibers are still hydrophobic and will undergo a scouring process to remove some of the "impurities” coating the cotton fiber.
- cellulose is the main component of a cotton fiber and is approximately 94% dry weight of a cotton fiber.
- a typical scouring process involves boiling the cotton fibers in a sodium hydroxide (20 - 50 g/liter) solution, for 1 - 8 hours, at a temperature greater than 120°C.
- the cellulose is the primary remaining material of the cotton fibers while the protein, pectic substances, waxes, and other non-cellulosic materials are removed.
- the cotton fibers are highly hydrophilic, and the appearance of the cotton fibers is clean and soft.
- Such hydrophilic cotton fibers have good body exudate acquisition, good breathability, and good softness.
- the natural pigment of the cotton fibers also remains in the cotton fibers and the cotton fibers can appear yellowish brown in color. Bleaching of the cotton fibers can bring about a white appearance to the cotton fibers as well as increase the overall absorbency of the cotton fibers and remove any final remaining impurities.
- the cotton fibers can be formed into a woven or nonwoven material via manufacturing processes such as, for example, spunlacing, through air bonding, air laying, wet laying, etc.
- manufacturing processes such as, for example, spunlacing, through air bonding, air laying, wet laying, etc.
- the woven or nonwoven material that is formed from the purified cotton fibers can undergo a finishing process wherein the woven or nonwoven material is chemically enhanced to alter the hydrophilic properties of the woven or nonwoven material.
- the cotton fibers are highly hydrophilic.
- topsheet layers While hydrophilicity facilitates absorption and penetration of body exudates through a topsheet layer of an absorbent article containing purified cotton fibers, such topsheet layers typically remain wet due to residual body exudates remaining in the topsheet layer and body exudates passing back into (and through) the topsheet layer from components underneath the topsheet layer, such as the absorbent core.
- the wearer of an absorbent article having a topsheet layer containing purified natural fibers such as, for example, cotton fibers may experience discomfort and lack of confidence in the absorbent article due to the residual body exudates remaining in the topsheet layer and passing back into (and through) the topsheet layer from components underneath the topsheet layer, such as the absorbent core.
- topsheet layers for reduced wetness (and rewet) based on chemical enhancements to the topsheet layer to provide the topsheet layer with hydrophobic properties.
- a hydrophobic chemical compound such as a paraffin-based or a silicone-based compound, has been used to treat the woven or nonwoven material.
- a chemically enhanced hydrophobic topsheet layer can help an absorbent article demonstrate an extended feeling of dryness at the skin-contacting surface of the absorbent article.
- topsheet layer acts as a one-way valve allowing moisture to pass in one direction and keeping it below the wearer-facing, skincontacting surface.
- chemically enhanced hydrophobic topsheet layers aren't suitable for a wearer of the absorbent article who may have sensitive skin and/or prefer absorbent products with a fully natural (i.e., non-chemically enhanced) topsheet layer.
- the purification process of the natural fibers can be altered from the typical purification process described herein.
- the raw natural fibers such as cotton
- the scouring step is the primary step within the typical purifying process in which the structure of the cotton fiber is modified in order to alter the natural hydrophobic character of the cotton fiber into a cotton fiber that has a hydrophilic character.
- the typical scouring process involves boiling the cotton fibers in a sodium hydroxide (20 - 50 g/liter) solution, for 1 - 8 hours, at a temperature greater than 120°C.
- the cellulose is the primary remaining material of the cotton fibers while the protein, pectic substances, waxes, and other non-cellulosic materials are removed.
- the waxes are the primary elements of the natural cotton fiber which provide the hydrophobic character to the cotton fiber. Removing the waxes from the cotton fiber results in the change of the cotton fiber from having a hydrophobic character to having a hydrophilic character.
- the altered scouring process step involves boiling the cotton fibers in a sodium hydroxide solution (0.1 - 10 g/L), for 30 minutes to 4 hours, at a temperature from 60 - 100°C.
- the altered scouring process step involves boiling the cotton fibers in a sodium hydroxide solution (0.5 - 2.0 g/L), for 2 - 3 hours, at a temperature from 80 - 90°C.
- a sodium hydroxide solution 0.5 - 2.0 g/L
- Such an altered scouring process can result in non-chemically enhanced cotton fibers which have a hydrophobic character.
- the non-chemically enhanced cotton fibers can have a water contact angle from 90° - 150°.
- the non-chemically enhanced cotton fibers can have a water contact angle from 130° - 140°.
- a topsheet layer made from such natural fibers can have non-chemically enhanced natural fibers which have a hydrophobic character resulting a reduction in the wetness that the wearer of the absorbent article may feel.
- the bleaching step can, in addition to removing any final remaining impurities following the typical scouring process, bring out a white appearance to the cotton fibers which is a change from their natural pigment which can appear yellowish brown in color.
- the bleaching step of the typical purification process can also remove impurities from the cotton fiber, and as the desire is to maintain the hydrophobic character of the cotton fibers without chemical enhancement, in the altered purification process, the bleaching step can be bypassed entirely.
- a topsheet layer made with nonbleached natural fibers, such as cotton fibers, according the modified purification process described herein, can have a Whiteness Index of less than 70 as measured by a CR-20 Color Reader manufactured by Konica Minolta.
- the topsheet layer may contain a plurality of apertures formed therethrough to permit body exudates to pass more readily into the absorbent core.
- the apertures may be randomly or uniformly arranged throughout the topsheet layer or they may be located in a narrow longitudinal band or strip arranged along the longitudinal centerline of the absorbent article. The size, shape, diameter, and number of apertures may be varied to suit an absorbent article's particular needs.
- the topsheet layer can have a basis weight ranging from about 5, 10, 15, 20 or 25 gsm to about 50, 100, 120, 125 or 150 gsm.
- a topsheet layer can be constructed from a through air bonded carded web having a basis weight ranging from about 15 gsm to about 100 gsm.
- the topsheet layer can be constructed from a cotton material and have a basis weight from about 25 gsm to about 35 gsm.
- An absorbent core can be positioned between the topsheet layer and the backsheet layer.
- the absorbent core can generally be any single layer structure or combination of layer components, which can demonstrate some level of compressibility, conformability, be non-irritating to a wearer's skin, and capable of absorbing and retaining liquids and other body exudates.
- the absorbent core can be formed from a variety of different materials and can contain any number of desired layers.
- the absorbent core can include one or more layers (e.g., two layers) of absorbent web material of cellulosic fibers (e.g., wood pulp fibers), other natural fibers, synthetic fibers, woven or nonwoven sheets, scrim netting, or other stabilizing structures, superabsorbent material, binder materials, surfactants, selected hydrophobic and hydrophilic materials, pigments, lotions, odor control agents or the like, as well as combinations thereof.
- the absorbent web material can include a matrix of cellulosic fluff and can also include superabsorbent material.
- the cellulosic fluff can comprise a blend of wood pulp fluff.
- An example of a wood pulp fluff can be identified with the trade designation NB 416, available from Weyerhaeuser Corp., and is a bleached, highly absorbent wood pulp containing primarily soft wood fibers.
- the absorbent core can include an optional amount of superabsorbent material.
- suitable superabsorbent material can include poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), poly(vinyl ether), maleic anhydride copolymers with vinyl ethers and o-olefins, poly(vinyl pyrrolidone), poly(vinylmorpholinone), poly(vinyl alcohol), and salts and copolymers thereof.
- superabsorbent materials can include unmodified natural polymers and modified natural polymers, such as hydrolyzed acrylonitrile-grafted starch, acrylic acid grafted starch, methyl cellulose, chitosan, carboxymethyl cellulose, hydroxypropyl cellulose, and natural gums, such as alginates, xanthan gum, locust bean gum, and so forth. Mixtures of natural and wholly or partially synthetic superabsorbent polymers can also be useful.
- the superabsorbent material can be present in the absorbent core in any amount as desired.
- the absorbent materials can be formed into a web structure by employing various conventional methods and techniques.
- the absorbent web can be formed by techniques such as, but not limited to, a dry-forming technique, an air forming technique, a wet forming technique, a foam forming technique, or the like, as well as combinations thereof. Methods and apparatus for carrying out such techniques are well known in the art.
- the shape of the absorbent core can vary as desired and can comprise any one of various shapes including, but not limited to, triangular, rectangular, dog-bone and elliptical shapes.
- the absorbent core can have a shape that generally corresponds with the overall shape of the absorbent article.
- the dimensions of the absorbent core can be substantially similar to those of the absorbent article, however, it will be appreciated that the dimensions of the absorbent core while similar, will often be less than those of the overall absorbent article, in order to be adequately contained therein.
- suitable materials and/or structures for the absorbent core can include, but are not limited to, those described in U.S. Patent Nos. 4,610,678 to Weisman, et al., 6,060,636 to Yahiaoui, et al., 6,610,903 to Latimer, et al., 7,358,282 to Krueger, et al., and U.S. Publication No. 2010/0174260 to Di Luccio, et al., each of which is hereby incorporated by reference thereto in its entirety.
- an absorbent core can be a single layer structure and can include, for example, a matrix of cellulosic fluff and superabsorbent material.
- an absorbent core can have at least two layers of material, such as, for example, a body facing layer and a garment facing layer.
- the two layers can be identical to each other.
- the two layers can be different from each other. In such embodiments, the two layers can provide the absorbent article with different absorption properties as deemed suitable.
- the body facing layer of the absorbent core may be constructed of an airlaid material and the garment facing layer of the absorbent core may be constructed of a superabsorbent polymer-containing compressed sheet.
- the airlaid material can have a basis weight from about 40 to about 200 gsm and the superabsorbent polymer-containing compressed sheet can be a cellulosic fluff based material that can be a combination of cellulosic pulp and SAP enclosed with a tissue carrier and having a basis weight from about 40 to about 400 gsm.
- the backsheet layer is generally liquid impermeable and is the portion of the absorbent article which faces the garment of the wearer.
- the backsheet layer can permit the passage of air or vapor out of the absorbent article while still blocking the passage of liquids.
- Any liquid impermeable material may generally be utilized to form the backsheet layer.
- the backsheet layer can be composed of a single layer or multiple layers, and these one or more layers can themselves comprise similar or different materials. Suitable material that may be utilized can be a microporous polymeric film, such as a polyolefin film of polyethylene or polypropylene, nonwovens and nonwoven laminates, and film/nonwoven laminates.
- the particular structure and composition of the backsheet layer can be selected from various known films and/or fabrics with the particular material being selected as appropriate to provide the desired level of liquid barrier, strength, abrasion resistance, tactile properties, aesthetics and so forth.
- a polyethylene film can be utilized that can have a thickness in the range of from about 0.2 or 0.5 mils to about 3.0 or 5.0 mils.
- An example of a backsheet layer can be a polyethylene film such as that obtainable from Pliant Corporation, Schaumburg, IL, USA. Another example can include calcium carbonate-filled polypropylene film.
- the backsheet layer can be a hydrophobic nonwoven material with water barrier properties such as a nonwoven laminate, an example of which can be a spunbond, meltblown, meltblown, spunbond, four-layered laminate.
- the backsheet layer can, therefore, be of a single or multiple layer construction, such as of multiple film layers or laminates of film and nonwoven fibrous layers.
- Suitable backsheet layers can be constructed from materials such as those described in U.S. Patent Nos.
- any ranges of values set forth in this disclosure contemplate all values within the range and are to be construed as support for claims reciting any subranges having endpoints which are whole number values within the specified range in question.
- a disclosure of a range of from 1 to 5 shall be considered to support claims to any of the following ranges: 1 to 5; 1 to 4; 1 to 3; 1 to 2; 2 to 5; 2 to 4; 2 to 3; 3 to 5; 3 to 4; and 4 to 5.
Abstract
The present disclosure is generally directed towards an absorbent article which can have an improved feeling of comfort next to the skin of the wearer and a reduction in the feelings of wetness and rewet. The absorbent article can have a wearer facing, liquid permeable topsheet layer and a garment facing, liquid impermeable backsheet layer. An absorbent core can be positioned between the topsheet layer and the backsheet layer. The topsheet layer can be formed from non-chemically enhanced natural fibers.
Description
TOPSHEET LAYER FOR AN ABSORBENT ARTICLE
BACKGROUND OF THE DISCLOSURE
Products such as absorbent articles are often used to collect and retain human body exudates containing, for example, urine, menses and/or blood. Comfort, absorbency, and discretion are three main product attributes and areas of concern for the wearer of the product. In particular, a wearer is often interested in knowing that such products will absorb significant volumes of body exudates with minimal leakage in order to protect their undergarments, outer garments, or bedsheets from staining, and that such products will help them avoid the subsequent embarrassment brought on by such staining.
Currently, a wide variety of products for absorption of body exudates are available in the form of feminine pads, sanitary napkins, panty shields, pantiliners, incontinence garments, diapers, training pants, youth pants, swim pants, and the like. These products generally have an absorbent core positioned between a body-facing liquid permeable topsheet layer and a garment-facing liquid impermeable backsheet layer. The edges of the topsheet and the backsheet layers are often bonded together at their periphery to form a seal to contain the absorbent core and body exudates received into the product through the topsheet layer.
Wearers of such conventional absorbent products are interested in having such products demonstrate reduced feelings of wetness once the product has been soiled or insulted during use. Unfortunately, once such a product has been soiled, the topsheet layer often remains wet or at least feels wet for some time throughout the period of use. The topsheet layer may frequently be absorbent, being made from hydrophilic construction materials, such as natural fibers. These materials often retain at their surface some noticeable moisture following soiling, thereby creating the uncomfortable wetness sensation during continued use of the product.
As a result of the desire of wearers to experience a reduced wetness sensation from a product during prolonged use (for both skin-health rationale as well as physical comfort), manufacturers have explored numerous technological approaches to address these feelings following soiling of the product. Manufacturers have attempted to reduce both the initial feelings of wetness and also continuing sensations of "rewet” wherein the product absorbs fluid or liquid such as menses or urine through the topsheet layer and delivers it to an interior layer of the absorbent article and subsequently releases the fluid or liquid under the continuing pressure of wear back to the topsheet layer from the interior layer. This release of fluid/liquid back to the topsheet layer often leads to the wearer's perception of continuing wetness. Manufacturers of such products have specifically designed
individual topsheet layers for reduced wetness (and rewet) based on chemical enhancements to the topsheet layer to provide the topsheet layer with hydrophobic properties. In this regard, hydrophobic topsheet layers can help an absorbent product demonstrate an extended feeling of dryness at the skincontacting surface of the product. Further, liquid/fluid that is retained in the interior layers of the product may have less of a propensity to pass back through the topsheet layer to the wearer's skin as a result of the hydrophobic interior surface properties of the topsheet layer. In some instances, therefore, the topsheet layer acts as a one-way valve allowing moisture to pass in one direction and keeping it below the user-facing, skin-contacting surface. However, such chemically enhanced hydrophobic topsheet layers aren't suitable for a consumer who may have sensitive skin and/or have a preference for absorbent products with a natural topsheet layer.
As a result, there remains a need for an improved product, such as an absorbent article, which has an improved feeling of comfort next to the skin of the wearer and has a reduction in the feelings of wetness and rewet without the need for chemical enhancement of the topsheet layer.
SUMMARY OF THE DISCLOSURE
In various embodiments, a topsheet layer for use in an absorbent article can have non-chemically enhanced natural fibers. In various embodiments, the natural fibers are cotton fibers.
In various embodiments, the natural fibers are present in an amount greater than 50% by weight by total weight of the topsheet layer. In various embodiments, the natural fibers are present in an amount greater than 75% by weight by total weight of the topsheet layer.
In various embodiments, the topsheet layer is hydrophobic. In various embodiments, the topsheet layer has a water contact angle from 90° to 150°. In various embodiments, the topsheet layer has a water contact angle from 130° to 140°.
In various embodiments, the topsheet layer has a whiteness index of less than 70.
In various embodiments, an absorbent article can have the topsheet layer described herein, a backsheet layer, and an absorbent core positioned between the topsheet layer and the backsheet layer.
In various embodiments, a method of manufacturing the topsheet layer described herein can have the step of scouring the natural fibers by boiling the natural fibers in a sodium hydroxide solution (0.1 - 10 g/L) for 30 - 240 minutes, at a temperature from 60° - 100°C. In various embodiments, the scouring of
the natural fibers is done by boiling the natural fibers in the sodium hydroxide solution (0.5 - 2.0 g/L), for 120 - 180 minutes, at a temperature from 80° - 90°C.
In various embodiments, the natural fibers are not bleached.
DETAILED DESCRIPTION OF THE DISLOSURE
The present disclosure is generally directed towards an absorbent article which can have an improved feeling of comfort next to the skin of the wearer and a reduction in the feelings of wetness and rewet. The absorbent article can have a wearer facing, liquid permeable topsheet layer and a garment facing, liquid impermeable backsheet layer. An absorbent core can be positioned between the topsheet layer and the backsheet layer. The topsheet layer and the backsheet layer can both extend beyond the outermost peripheral edges of the absorbent core and can be peripherally bonded together, either entirely or partially, using known bonding techniques to form a sealed peripheral region. For example, the topsheet layer and the backsheet layer can be bonded together by adhesive bonding, ultrasonic bonding, or any other suitable bonding method known in the art. The topsheet layer can be formed from non-chemically enhanced natural fibers.
Definitions:
As used herein, the term "absorbent article” refers herein to a garment or other end-use personal care absorbent article, including, but not limited to, sanitary napkins, feminine pads, pantiliners, panty shields, incontinence garments, diapers, training pants, youth pants, swim pants, and the like.
As used herein, the term "airlaid” refers herein to a web manufactured by an airlaying process. In the airlaying process, bundles of small fibers having typical lengths ranging from about 3 to about 52 mm are separated and entrained in an air supply and then deposited onto a forming screen, usually with the assistance of a vacuum supply. The randomly deposited fibers are then bonded to one another using, for example, hot air to activate a binder component or a latex adhesive. Airlaying is taught in, for example, U.S. Patent No. 4,640,810 to Laursen, et al., which is incorporated herein in its entirety by reference thereto for all purposes.
As used herein, the term "bonded” refers herein to the joining, adhering, connecting, attaching, or the like, of two elements. Two elements will be considered bonded together when they are joined, adhered, connected, attached, or the like, directly to one another or indirectly to one another, such as when bonded to an intermediate element. The bonding can occur via, for example, adhesive, pressure bonding, thermal bonding, ultrasonic bonding, stitching, suturing, and/or welding.
As used herein, the term "bonded carded web” refers herein to webs that are made from staple fibers which are sent through a combing or carding unit which separates or breaks apart and aligns the staple fibers in the machine direction to form a generally machine direction oriented fibrous nonwoven web. This material may be bonded together by methods that can include point bonding, through air bonding, ultrasonic bonding, adhesive bonding, etc.
As used herein, the term "hydrophilic” refers to surfaces with a water contact angle less than 90°.
As used herein, the term "hydrophobic” refers to surfaces with the property to repel fluid with a water contact angle from 90° to 150°
As used herein, the term "super-hydrophobic” refers to surfaces with a water contact angle greater than 150°.
As used herein, the term "machine direction” (MD) refers to the length of a fabric in the direction in which it is produced, as opposed to a "cross-machine direction” (CD) which refers to the width of a fabric in a direction generally perpendicular to the machine direction.
As used herein, the term "meltblown web” refers herein to a nonwoven web that is formed by a process in which a molten thermoplastic material is extruded through a plurality of fine, usually circular, die capillaries as molten fibers into converging high velocity gas (e.g., air) streams that attenuate the fibers of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly disbursed meltblown fibers. Such a process is disclosed, for example, in U.S. Patent No. 3,849,241 to Butin, et al., which is incorporated herein in its entirety by reference thereto for all purposes. Generally speaking, meltblown fibers may be microfibers that are substantially continuous or discontinuous, generally smaller than 10 microns in diameter, and generally tacky when deposited onto a collecting surface.
As used herein, the term "nonwoven fabric” or "nonwoven web” refers herein to a web having a structure of individual fibers or threads which are interlaid, but not in an identifiable manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as, for example, meltblowing processes, spunbonding processes, through-air bonded carded web (also known as BCW and TABCW) processes, etc. The basis weight of nonwoven webs may generally vary, such as, from about 5, 10 or 20 gsm to about 120, 125 or 150 gsm.
As used herein, the term "spunbond web” refers herein to a web containing small diameter substantially continuous fibers. The fibers are formed by extruding a molten thermoplastic material
from a plurality of fine, usually circular, capillaries of a spinneret with the diameter of the extruded fibers then being rapidly reduced as by, for example, eductive drawing and/or other well-known spunbonding mechanisms. The production of spunbond webs is described and illustrated, for example, in U.S. Patent Nos. 4,340,563 to Appel, et al., 3,692,618 to Dorschner, et al., 3,802,817 to Matsuki, et al., 3,338,992 to Kinney, 3,341 ,394 to Kinney, 3,502,763 to Hartman, 3,502,538 to Levy, 3,542,615 to Dobo, et al., and 5,382,400 to Pike, et al., which are each incorporated herein in their entirety by reference thereto for all purposes. Spunbond fibers are generally not tacky when they are deposited onto a collecting surface. Spunbond fibers may sometimes have diameters less than about 40 microns, and often between about 5 to about 20 microns.
As used herein, the terms "superabsorbent polymer,” "superabsorbent” or "SAP” shall be used interchangeably and shall refer to polymers that can absorb and retain extremely large amounts of a liquid relative to their own mass. Water absorbing polymers, which are classified as hydrogels, which can be cross-linked, absorb aqueous solutions through hydrogen bonding and other polar forces with water molecules. A SAP's ability to absorb water is based in part on ionicity (a factor of the ionic concentration of the aqueous solution), and the SAP functional polar groups that have an affinity for water. SAP are typically made from the polymerization of acrylic acid blended with sodium hydroxide in the presence of an initiator to form a poly-acrylic acid sodium salt (sometimes referred to as sodium polyacrylate). Other materials are also used to make a superabsorbent polymer, such as polyacrylamide copolymer, ethylene maleic anhydride copolymer, cross-linked carboxymethylcellulose, polyvinyl alcohol copolymers, cross-linked polyethylene oxide, and starch grafted copolymer of polyacrylonitrile. SAP may be present in absorbent articles in particle or fibrous form or as a coating on another material or fiber.
Absorbent article:
The present disclosure is generally directed towards an absorbent article which can have an improved feeling of comfort next to the skin of the wearer and a reduction in the feelings of wetness and rewet. The absorbent article can have a wearer facing, liquid permeable topsheet layer and a garment facing, liquid impermeable backsheet layer. An absorbent core can be positioned between the topsheet layer and the backsheet layer. The topsheet layer and the backsheet layer can both extend beyond the outermost peripheral edges of the absorbent core and can be peripherally bonded together, either entirely or partially, using known bonding techniques to form a sealed peripheral region. For example, the topsheet layer and the backsheet layer can be bonded together by adhesive bonding, ultrasonic bonding, or any other suitable bonding method known in the art. The topsheet layer can be formed from non-chemically enhanced natural fibers.
Topsheet Layer:
The topsheet layer defines a wearer facing surface of the absorbent article that may directly contact the body of the wearer and is liquid permeable to receive body exudates. The topsheet layer is desirably provided for comfort and conformability and functions to direct body exudates away from the body of the wearer, through its own structure, and towards the absorbent core. The topsheet layer desirably retains little to no liquid in its structure, so that it provides a relatively comfortable and nonirritating surface next to the skin of the wearer of the absorbent article.
The topsheet layer can be constructed of any woven or nonwoven sheet material which is easily penetrated by bodily exudates which may contact the body-facing surface of the topsheet layer. In various embodiments, the topsheet layer can be constructed from various nonwoven webs such as, for example, hydroentangled spunlace webs or through air bonded carded webs. In various embodiments, the topsheet layer can be constructed of natural fibers. Examples of suitable natural fibers can include, but are not limited to, cotton fibers, rayon fibers, wheat straw fibers, rice straw fibers, flax fibers, bamboo fibers, jute fibers, hemp fibers, sisal fibers, bagasse fibers, hesperaloe fibers, miscanthus, marine or freshwater algae/seaweeds, and combinations thereof. In various embodiments, the natural fibers can be cotton fibers, bamboo fibers, or combinations thereof. In various embodiments, the natural fibers can be cotton fibers. In various embodiments, the topsheet layer has at least 50, 60, 75, 95, 99, or 100% by weight of natural fibers by total weight of the topsheet layer. In various embodiments, the topsheet layer has at least 75, 95, 99, or 100% by weight of natural fibers by total weight of the topsheet layer. In various embodiments, the topsheet layer has at least 95, 99, or 100% by weight of natural fibers by total weight of the topsheet layer.
Natural fibers which are still in their raw form (i.e., haven't undergone any purification steps) are hydrophobic. Typical purification steps include ginning, carding, combing, scouring, and bleaching. For example, with regard to cotton fibers, ginning is the first step in purifying raw cotton and separating the cotton lint from the cotton seed and other foreign matter debris (e.g., plant stalk, plant stem, and plant leaves). The cotton lint then undergoes carding to remove tangles within the cotton lint, individualize and align the cotton fibers within the cotton lint, and remove foreign matter debris that passed through the ginning step. The carded cotton fibers proceed through a combing step in which any final remaining foreign matter debris is removed, and the cotton fibers are smoothed. Following ginning, carding, and combing, the cotton fibers are still hydrophobic and will undergo a scouring process to remove some of the "impurities” coating the cotton fiber. For example, regarding cotton fiber, cellulose is the main component of a cotton fiber and is approximately 94% dry weight of a cotton fiber. Other components (approximate % dry weight of cotton fiber) of a cotton fiber are protein
(1 .3%), pectic substances (1 .2%), ash (1 .2%), wax (0.6%), total sugars (0.3%), pigments (trace), and other non-cellulosic material (1 .4%) (Industrial Crops and Products, 11 (2-3):173-178, March 2000). Scouring is a process during which protein, pectic substances, waxes, and other non-cellulosic materials are removed from the cotton fibers to produce a hydrophilic cotton fiber. A typical scouring process involves boiling the cotton fibers in a sodium hydroxide (20 - 50 g/liter) solution, for 1 - 8 hours, at a temperature greater than 120°C. Following the scouring process, the cellulose is the primary remaining material of the cotton fibers while the protein, pectic substances, waxes, and other non-cellulosic materials are removed. Following the scouring process, the cotton fibers are highly hydrophilic, and the appearance of the cotton fibers is clean and soft. Such hydrophilic cotton fibers have good body exudate acquisition, good breathability, and good softness. Following the typical scouring process, the natural pigment of the cotton fibers also remains in the cotton fibers and the cotton fibers can appear yellowish brown in color. Bleaching of the cotton fibers can bring about a white appearance to the cotton fibers as well as increase the overall absorbency of the cotton fibers and remove any final remaining impurities.
Following the purification process, the cotton fibers can be formed into a woven or nonwoven material via manufacturing processes such as, for example, spunlacing, through air bonding, air laying, wet laying, etc. To increase suitability for usage in an absorbent article, such as, for example, as the topsheet layer of the absorbent article, the woven or nonwoven material that is formed from the purified cotton fibers, can undergo a finishing process wherein the woven or nonwoven material is chemically enhanced to alter the hydrophilic properties of the woven or nonwoven material. Following the purification process, the cotton fibers are highly hydrophilic. While hydrophilicity facilitates absorption and penetration of body exudates through a topsheet layer of an absorbent article containing purified cotton fibers, such topsheet layers typically remain wet due to residual body exudates remaining in the topsheet layer and body exudates passing back into (and through) the topsheet layer from components underneath the topsheet layer, such as the absorbent core. The wearer of an absorbent article having a topsheet layer containing purified natural fibers such as, for example, cotton fibers, may experience discomfort and lack of confidence in the absorbent article due to the residual body exudates remaining in the topsheet layer and passing back into (and through) the topsheet layer from components underneath the topsheet layer, such as the absorbent core. As a result of the desire of wearers to experience a reduced wetness sensation from a product during prolonged use (for both skin-health rationale as well as physical comfort), manufacturers have explored numerous technological approaches to address these feelings following soiling of the product. Manufacturers have attempted to reduce both the initial feelings of wetness and also continuing sensations of "rewet” wherein the product absorbs fluid or liquid such as menses or urine
through the topsheet layer and delivers it to an interior layer of the absorbent article and subsequently releases the fluid or liquid under the continuing pressure of wear back to the topsheet layer from the interior layer. This release of fluid/liquid back to the topsheet layer often leads to the wearer's perception of continuing wetness. Manufacturers of such products have specifically designed individual topsheet layers for reduced wetness (and rewet) based on chemical enhancements to the topsheet layer to provide the topsheet layer with hydrophobic properties. To chemically alter the hydrophilic properties of the woven or nonwoven material containing purified natural fibers, such as, cotton fibers, a hydrophobic chemical compound, such as a paraffin-based or a silicone-based compound, has been used to treat the woven or nonwoven material. In this regard, a chemically enhanced hydrophobic topsheet layer can help an absorbent article demonstrate an extended feeling of dryness at the skin-contacting surface of the absorbent article. Further, body exudate that is retained in the interior layers of the absorbent article may have less of a propensity to pass back through the topsheet layer to the wearer's skin as a result of the hydrophobic interior surface properties of the topsheet layer. In some instances, therefore, the topsheet layer acts as a one-way valve allowing moisture to pass in one direction and keeping it below the wearer-facing, skincontacting surface. However, such chemically enhanced hydrophobic topsheet layers aren't suitable for a wearer of the absorbent article who may have sensitive skin and/or prefer absorbent products with a fully natural (i.e., non-chemically enhanced) topsheet layer.
To provide the wearer of an absorbent article with an absorbent article having a topsheet layer formed from non-chemically enhanced natural fibers while still providing the wearer with an absorbent article having a topsheet layer with hydrophobic properties, the purification process of the natural fibers, particularly of cotton fibers, can be altered from the typical purification process described herein. The raw natural fibers, such as cotton, can still undergo ginning, carding, and combing as described herein as those processes are mechanical steps utilized to purify the raw cotton. The scouring step, however, is the primary step within the typical purifying process in which the structure of the cotton fiber is modified in order to alter the natural hydrophobic character of the cotton fiber into a cotton fiber that has a hydrophilic character. The typical scouring process involves boiling the cotton fibers in a sodium hydroxide (20 - 50 g/liter) solution, for 1 - 8 hours, at a temperature greater than 120°C. Following the scouring process, the cellulose is the primary remaining material of the cotton fibers while the protein, pectic substances, waxes, and other non-cellulosic materials are removed. The waxes are the primary elements of the natural cotton fiber which provide the hydrophobic character to the cotton fiber. Removing the waxes from the cotton fiber results in the change of the cotton fiber from having a hydrophobic character to having a hydrophilic character. Completely eliminating the scouring process from the purification process is not feasible as, in addition to the waxes, other
impurities would remain with the cotton fiber including protein, pectic substances, and other non- cellulosic materials. These impurities need to be removed from the cotton fiber while maintaining the presence of the waxes. The scouring process, therefore, can be altered to maintain waxes which maintain the hydrophobic character of the cotton fiber while removing impurities such as, protein, pectic substances, and other non-cellulosic materials from the cotton fiber. In various embodiments, the altered scouring process step involves boiling the cotton fibers in a sodium hydroxide solution (0.1 - 10 g/L), for 30 minutes to 4 hours, at a temperature from 60 - 100°C. In various embodiments, the altered scouring process step involves boiling the cotton fibers in a sodium hydroxide solution (0.5 - 2.0 g/L), for 2 - 3 hours, at a temperature from 80 - 90°C. Such an altered scouring process can result in non-chemically enhanced cotton fibers which have a hydrophobic character. In various embodiments, the non-chemically enhanced cotton fibers can have a water contact angle from 90° - 150°. In various embodiments, the non-chemically enhanced cotton fibers can have a water contact angle from 130° - 140°. Following the altered scouring process, a topsheet layer made from such natural fibers, such as cotton fibers, can have non-chemically enhanced natural fibers which have a hydrophobic character resulting a reduction in the wetness that the wearer of the absorbent article may feel.
As described herein, within the typical purification process, the bleaching step can, in addition to removing any final remaining impurities following the typical scouring process, bring out a white appearance to the cotton fibers which is a change from their natural pigment which can appear yellowish brown in color. As the bleaching step of the typical purification process can also remove impurities from the cotton fiber, and as the desire is to maintain the hydrophobic character of the cotton fibers without chemical enhancement, in the altered purification process, the bleaching step can be bypassed entirely. As the bleaching step can be bypassed entirely, a topsheet layer made with nonbleached natural fibers, such as cotton fibers, according the modified purification process described herein, can have a Whiteness Index of less than 70 as measured by a CR-20 Color Reader manufactured by Konica Minolta.
In various embodiments, the topsheet layer may contain a plurality of apertures formed therethrough to permit body exudates to pass more readily into the absorbent core. The apertures may be randomly or uniformly arranged throughout the topsheet layer or they may be located in a narrow longitudinal band or strip arranged along the longitudinal centerline of the absorbent article. The size, shape, diameter, and number of apertures may be varied to suit an absorbent article's particular needs.
In various embodiments, the topsheet layer can have a basis weight ranging from about 5, 10, 15, 20 or 25 gsm to about 50, 100, 120, 125 or 150 gsm. For example, in an embodiment, a topsheet layer
can be constructed from a through air bonded carded web having a basis weight ranging from about 15 gsm to about 100 gsm. In various embodiments, the topsheet layer can be constructed from a cotton material and have a basis weight from about 25 gsm to about 35 gsm.
Absorbent core:
An absorbent core can be positioned between the topsheet layer and the backsheet layer. The absorbent core can generally be any single layer structure or combination of layer components, which can demonstrate some level of compressibility, conformability, be non-irritating to a wearer's skin, and capable of absorbing and retaining liquids and other body exudates. In various embodiments, the absorbent core can be formed from a variety of different materials and can contain any number of desired layers. For example, the absorbent core can include one or more layers (e.g., two layers) of absorbent web material of cellulosic fibers (e.g., wood pulp fibers), other natural fibers, synthetic fibers, woven or nonwoven sheets, scrim netting, or other stabilizing structures, superabsorbent material, binder materials, surfactants, selected hydrophobic and hydrophilic materials, pigments, lotions, odor control agents or the like, as well as combinations thereof. In an embodiment, the absorbent web material can include a matrix of cellulosic fluff and can also include superabsorbent material. The cellulosic fluff can comprise a blend of wood pulp fluff. An example of a wood pulp fluff can be identified with the trade designation NB 416, available from Weyerhaeuser Corp., and is a bleached, highly absorbent wood pulp containing primarily soft wood fibers.
In various embodiments, if desired, the absorbent core can include an optional amount of superabsorbent material. Examples of suitable superabsorbent material can include poly(acrylic acid), poly(methacrylic acid), poly(acrylamide), poly(vinyl ether), maleic anhydride copolymers with vinyl ethers and o-olefins, poly(vinyl pyrrolidone), poly(vinylmorpholinone), poly(vinyl alcohol), and salts and copolymers thereof. Other superabsorbent materials can include unmodified natural polymers and modified natural polymers, such as hydrolyzed acrylonitrile-grafted starch, acrylic acid grafted starch, methyl cellulose, chitosan, carboxymethyl cellulose, hydroxypropyl cellulose, and natural gums, such as alginates, xanthan gum, locust bean gum, and so forth. Mixtures of natural and wholly or partially synthetic superabsorbent polymers can also be useful. The superabsorbent material can be present in the absorbent core in any amount as desired.
Regardless of the combination of absorbent materials used in the absorbent core, the absorbent materials can be formed into a web structure by employing various conventional methods and techniques. For example, the absorbent web can be formed by techniques such as, but not limited to, a dry-forming technique, an air forming technique, a wet forming technique, a foam forming technique,
or the like, as well as combinations thereof. Methods and apparatus for carrying out such techniques are well known in the art.
The shape of the absorbent core can vary as desired and can comprise any one of various shapes including, but not limited to, triangular, rectangular, dog-bone and elliptical shapes. In various embodiments, the absorbent core can have a shape that generally corresponds with the overall shape of the absorbent article. The dimensions of the absorbent core can be substantially similar to those of the absorbent article, however, it will be appreciated that the dimensions of the absorbent core while similar, will often be less than those of the overall absorbent article, in order to be adequately contained therein.
By way of example, suitable materials and/or structures for the absorbent core can include, but are not limited to, those described in U.S. Patent Nos. 4,610,678 to Weisman, et al., 6,060,636 to Yahiaoui, et al., 6,610,903 to Latimer, et al., 7,358,282 to Krueger, et al., and U.S. Publication No. 2010/0174260 to Di Luccio, et al., each of which is hereby incorporated by reference thereto in its entirety.
As described above, in various embodiments, an absorbent core can be a single layer structure and can include, for example, a matrix of cellulosic fluff and superabsorbent material. In various embodiments, an absorbent core can have at least two layers of material, such as, for example, a body facing layer and a garment facing layer. In various embodiments, the two layers can be identical to each other. In various embodiments, the two layers can be different from each other. In such embodiments, the two layers can provide the absorbent article with different absorption properties as deemed suitable. In various embodiments, the body facing layer of the absorbent core may be constructed of an airlaid material and the garment facing layer of the absorbent core may be constructed of a superabsorbent polymer-containing compressed sheet. In such embodiments, the airlaid material can have a basis weight from about 40 to about 200 gsm and the superabsorbent polymer-containing compressed sheet can be a cellulosic fluff based material that can be a combination of cellulosic pulp and SAP enclosed with a tissue carrier and having a basis weight from about 40 to about 400 gsm.
Backsheet Layer:
The backsheet layer is generally liquid impermeable and is the portion of the absorbent article which faces the garment of the wearer. The backsheet layer can permit the passage of air or vapor out of the absorbent article while still blocking the passage of liquids. Any liquid impermeable material may generally be utilized to form the backsheet layer. The backsheet layer can be composed of a single layer or multiple layers, and these one or more layers can themselves comprise similar or different
materials. Suitable material that may be utilized can be a microporous polymeric film, such as a polyolefin film of polyethylene or polypropylene, nonwovens and nonwoven laminates, and film/nonwoven laminates. The particular structure and composition of the backsheet layer can be selected from various known films and/or fabrics with the particular material being selected as appropriate to provide the desired level of liquid barrier, strength, abrasion resistance, tactile properties, aesthetics and so forth. In various embodiments, a polyethylene film can be utilized that can have a thickness in the range of from about 0.2 or 0.5 mils to about 3.0 or 5.0 mils. An example of a backsheet layer can be a polyethylene film such as that obtainable from Pliant Corporation, Schaumburg, IL, USA. Another example can include calcium carbonate-filled polypropylene film. In still another embodiment, the backsheet layer can be a hydrophobic nonwoven material with water barrier properties such as a nonwoven laminate, an example of which can be a spunbond, meltblown, meltblown, spunbond, four-layered laminate. The backsheet layer can, therefore, be of a single or multiple layer construction, such as of multiple film layers or laminates of film and nonwoven fibrous layers. Suitable backsheet layers can be constructed from materials such as those described in U.S. Patent Nos. 4,578,069 to Whitehead, et al., 4,376,799 to Tusim, et al., 5,695,849 to Shawver, et al., 6,075,179 to McCormack, et al., and 6,376,095 to Cheung, et al., each of which are hereby incorporated by reference thereto in its entirety.
In the interests of brevity and conciseness, any ranges of values set forth in this disclosure contemplate all values within the range and are to be construed as support for claims reciting any subranges having endpoints which are whole number values within the specified range in question. By way of hypothetical example, a disclosure of a range of from 1 to 5 shall be considered to support claims to any of the following ranges: 1 to 5; 1 to 4; 1 to 3; 1 to 2; 2 to 5; 2 to 4; 2 to 3; 3 to 5; 3 to 4; and 4 to 5.
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 written document conflicts with any meaning or definition of the term in a document incorporated by references, the meaning or definition assigned to the term in this written 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. When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles "a”, "an”, "the” and "said” are intended to mean that there are one or more of the elements. The terms "comprising”, "including” and "having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Many modifications and variations of the present disclosure can be made without departing from the spirit and scope thereof. Therefore, the exemplary embodiments described above should not be used to limit the scope of the invention.
Claims
1. A topsheet layer for use in an absorbent article, the topsheet layer comprising non-chemically enhanced natural fibers.
2. The topsheet layer of claim 1 wherein the natural fibers are cotton fibers.
3. The topsheet layer of claim 1 wherein the natural fibers are present in an amount greater than 50% by weight by total weight of the topsheet layer.
4. The topsheet layer of claim 3 wherein the natural fibers are present in an amount greater than 75% by weight by total weight of the topsheet layer.
5. The topsheet layer of claim 1 wherein the topsheet layer is hydrophobic.
6. The topsheet layer of claim 5 wherein the topsheet layer has a water contact angle from 90° to 150°.
7. The topsheet layer of claim 6 wherein the topsheet layer has a water contact angle from 130° to 140°.
8. The topsheet layer of claim 1 wherein the topsheet layer has a whiteness index of less than 70.
9. An absorbent article comprising the topsheet layer of claim 1 , a backsheet layer, and an absorbent core positioned between the topsheet layer and the backsheet layer.
10. A method of manufacturing the topsheet layer of claim 1 , the method comprising the step of scouring the natural fibers by boiling the natural fibers in a sodium hydroxide solution (0.1 - 10 g/L) for 30 - 240 minutes, at a temperature from 60° - 100°C.
11. The method of claim 10 wherein the scouring of the natural fibers is done by boiling the natural fibers in the sodium hydroxide solution (0.5 - 2.0 g/L), for 120 - 180 minutes, at a temperature from 80° - 90°C.
12. The method of claim 10 wherein the natural fibers are not bleached.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/US2021/048347 WO2023033796A1 (en) | 2021-08-31 | 2021-08-31 | Topsheet layer for an absorbent article |
KR1020247010069A KR20240051215A (en) | 2021-08-31 | 2021-08-31 | Top sheet layer for absorbent articles |
CN202180101786.4A CN117835946A (en) | 2021-08-31 | 2021-08-31 | Topsheet layer for absorbent article |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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PCT/US2021/048347 WO2023033796A1 (en) | 2021-08-31 | 2021-08-31 | Topsheet layer for an absorbent article |
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WO2023033796A1 true WO2023033796A1 (en) | 2023-03-09 |
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Application Number | Title | Priority Date | Filing Date |
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PCT/US2021/048347 WO2023033796A1 (en) | 2021-08-31 | 2021-08-31 | Topsheet layer for an absorbent article |
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KR (1) | KR20240051215A (en) |
CN (1) | CN117835946A (en) |
WO (1) | WO2023033796A1 (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030226209A1 (en) * | 2002-02-22 | 2003-12-11 | Kanke Fuminori | Bleaching method of natural fibers without dewaxing |
US20040058072A1 (en) * | 2000-09-29 | 2004-03-25 | Rearick William A. | Cellulosic substrates with reduced absorbent capacity having the capability to wick liquids |
US20190231612A1 (en) * | 2017-10-19 | 2019-08-01 | The Procter & Gamble Company | Topsheet comprising natural fibers with good mechanical strength |
-
2021
- 2021-08-31 CN CN202180101786.4A patent/CN117835946A/en active Pending
- 2021-08-31 WO PCT/US2021/048347 patent/WO2023033796A1/en unknown
- 2021-08-31 KR KR1020247010069A patent/KR20240051215A/en unknown
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20040058072A1 (en) * | 2000-09-29 | 2004-03-25 | Rearick William A. | Cellulosic substrates with reduced absorbent capacity having the capability to wick liquids |
US20030226209A1 (en) * | 2002-02-22 | 2003-12-11 | Kanke Fuminori | Bleaching method of natural fibers without dewaxing |
US20190231612A1 (en) * | 2017-10-19 | 2019-08-01 | The Procter & Gamble Company | Topsheet comprising natural fibers with good mechanical strength |
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KR20240051215A (en) | 2024-04-19 |
CN117835946A (en) | 2024-04-05 |
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