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
• • 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
  • A61F13/53—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 absorbing medium
  • A61F13/534—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 absorbing medium having an inhomogeneous composition through the thickness of the pad
• • 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
  • A61F13/20—Tampons, e.g. catamenial tampons; Accessories therefor
• • 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
  • A61F13/514—Backsheet, i.e. the impermeable cover or layer furthest from the skin
  • A61F13/51456—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by its properties
  • A61F13/51458—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by its properties being air-pervious or breathable
  • A61F13/5146—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by its properties being air-pervious or breathable having apertures of perforations
• • 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
  • A61F13/45—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 shape
  • A61F13/47—Sanitary towels, incontinence pads or napkins
• • 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
  • A61F13/514—Backsheet, i.e. the impermeable cover or layer furthest from the skin
  • A61F13/51474—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by its structure
  • A61F13/51478—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by its structure being a laminate, e.g. multi-layered or with several layers
  • A61F13/5148—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by its structure being a laminate, e.g. multi-layered or with several layers having an impervious inner layer and a cloth-like outer layer
• • 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
  • A61F2013/51059—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 being sprayed with chemicals
  • A61F2013/51061—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 being sprayed with chemicals for rendering the surface hydrophobic
• • 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
  • A61F13/53—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 absorbing medium
  • A61F2013/530868—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 absorbing medium characterized by the liquid distribution or transport means other than wicking layer
  • A61F2013/530897—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 absorbing medium characterized by the liquid distribution or transport means other than wicking layer having capillary means, e.g. pore or fibre size gradient
  • A61F2013/530912—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 absorbing medium characterized by the liquid distribution or transport means other than wicking layer having capillary means, e.g. pore or fibre size gradient being hydrophobic

Definitions

• a second aspect of the present invention relates to the situation wherein the garment facing surface of at least one of the layers in the lower portion has a fluid contact angle greater than the fluid contact angle of the wearer facing surface of the same layer.
• a further aspect of the present invention relates to a process for the production of an absorbent article described above comprising the step of applying a low surface energy material to the surface of at least one of the layers in the lower portion.
• Another aspect of the present invention relates to a process for the production of an absorbent article described above comprising the step of incorporating a low surface energy material within one of the layers in the lower portion.
• Fig. 1 Top plan view of a first embodiment of an absorbent article of the present invention with portions cut away to show its construction.
• Fig. 2 Enlarged cross sectional view of a backsheet of the present invention taken along line I-l of Fig. 1.
• the present invention relates to absorbent disposable articles such as sanitary napkins (1), baby diapers, incontinence products and panty liners.
• sanitary napkins (1) such as sanitary napkins (1), baby diapers, incontinence products and panty liners.
• Such products comprise a liquid pervious topsheet (2) , a backsheet (3) and an absorbent core (4) intermediate said topsheet (2) and said backsheet (3).
• the topsheet (2), backsheet (3) and core (4) each have a wearer facing surface and a garment facing surface.
• the garment facing surface of the topsheet and the wearer facing surface of the backsheet are joined to one another at the periphery (5) of said absorbent article.
• the absorbent article has wings, side wrapping elements or sideflaps.
• the absorbent gelling materials are capable of absorbing large quantities of aqueous body fluids, and are further capable of retaining such absorbed fluids under moderate pressures.
• the absorbent gelling materials can be dispersed homogeneously or non-homogeneously in a suitable carrier.
• the suitable carriers provided they are absorbent as such, can also be used alone.
• the topsheet (21) as a whole and hence each layer individually needs to be compliant, soft feeling, and non-irritating to the wearer's skin. It also can have elastic characteristics allowing it to be stretched in one or two directions.
• the topsheet may be formed from any of the materials available for this purpose and known in the art, such as non woven fabrics, films or combinations of both.
• at least one of the layers (preferably the upper layer) of the topsheet comprises a liquid permeable apertured polymeric film (22).
• the upper layer is provided by a film material having apertures which are provided to facilitate liquid transport from the wearer facing surface towards the absorbent structure, as detailed for example in US 3 929 135, US 4 151 240, US 4 319 868, US 4 324 426, US 4 343 314 and US 4 591 523.
• uni directional refers to materials which have at least a substantially, if not complete, one directional fluid transport in the direction of the core. Fluid directionality may be identified using the test method 3 detailed herein under test methods.
• the apertured first layer of the backsheet (25) comprises a layer having discrete apertures (28) which extend beyond the horizontal plane of the garment facing surface of the layer towards the core thereby forming protuberances (29).
• Each protuberance has an orifice located at its terminating end.
• Preferably said protuberances have a funnel or conical shape, similar to those described in US 3, 929,135.
• the apertures located within the plane of the layer and the orifices located at the terminating end of protruberance themselves maybe circular or non circular. In any case the cross sectional dimension or area of the orifice at the termination of the protuberance is smaller than the cross sectional dimension or area of the aperture located within the plane of the layer.
• the first layer of the backsheet typically has an open area of more than 5%, preferably from 10% to 35% of the total film layer area. The open area of the layer can be determined using the test method 4 detailed herein under test methods.
• the second layer of said backsheet comprises a gas permeable fibrous fabric layer (26) composed of polymeric fibres such as polymeric non wovens known in the art.
• the fibrous fibre layer preferably has a basis weight of 10 to 100g/m2, more preferably 15 to 30g/m 2 .
• the fibres can be made of any polymeric material, in particular, fibres of polyethylene, polypropylene, polyester polyacetate or combinations thereof (inter- and intra fibre combinations) and also mixtures of synthetic fibres and non absorbent natural fibres or treated natural fibres such as cotton may be utilised.
• the fibres are preferably spunbonded, carded or melt blown.
• the backsheet typically extends across the whole of the absorbent structure and can extend into and form part of or all of the preferred sideflaps, side wrapping elements or wings. Fluid contact angle
• the contact angle gradient may be present in said lower portion between any surface (wearer facing or garment facing) of any layer therein.
• the fluid contact angle gradient may be present across the wearer and garment facing surface of the same layer or between the garment facing surface of at least one layer in the lower portion and an adjacent surface of an adjacent layer, i.e. between the wearer and the garment facing surface of the first layer of the backsheet, between the garment facing surface of the first layer and the wearer facing surface of the second layer of the backsheet, between the wearer and the garment facing surface of the second layer of the backsheet or between any subsequent backsheet layers.
• combinations of these layers each exhibiting a specific contact angle relation be utilised thereby producing a continuous gradient in contact angles in the lower portion.
• hydrophilic is used to refer to surfaces that are wettable by aqueous fluids (e.g., aqueous body fluids) deposited thereon. Hydrophilicity and wettability are typically defined in terms of contact angle and the surface tension of the fluids and solid surfaces involved. This is discussed in detail in the American Chemical Society publication entitled Contact Angle. Wettability and Adhesion, edited by Robert F. Gould (Copyright 1964), which is hereby incorporated herein by reference. A surface is said to be wetted by an aqueous fluid (hydrophilic) when the fluid tends to spread spontaneously across the surface. Conversely, a surface is considered to be “hydrophobic” if the aqueous fluid does not tend to spread spontaneously across the surface.
• the liquid/solid contact angle depends on surface inhomogeneities (e.g., chemical and physical properties, such as roughness), contamination, chemical/physical treatment of or composition of the solid surface, as well as the nature of the liquid and its contamination.
• the surface energy of the solid also influences the contact angle. As the surface energy of the solid decreases, the contact angle increases. As the surface energy of the solid increases, the contact angle decreases.
• W is the work of adhesion measured in erg/ cm 2
• G is the surface tension of the liquid measured in dyne/cm, (xlO ⁇ Nnrr-') and
• A is the liquid-solid contact angle measured in degrees.
• the work of adhesion increases with the cosine of the liquid-solid contact angle (reaching a maximum where the contact angle A is zero).
• Table 1 is useful to illustrate the relationship between solid-liquid contact angle and work of adhesion for a particular fluid (e.g., water), whose surface tension is 75 dynes/cm (75x10 ⁇ 3jm ⁇ 2).
• a particular fluid e.g., water
• surface tension 75 dynes/cm (75x10 ⁇ 3jm ⁇ 2).
• Fig 4. illustrates a droplet of fluid 110 which is located on a solid surface having two regions 113 and 115 having differing surface energies (indicated by the different cross-hatching for illustrative pu ⁇ oses).
• region 113 exhibits a comparatively lower surface energy than region 115, and hence a reduced wettability for the fluid of the droplet than region 115.
• the droplet 110 produces a contact angle A(b) at the edge of the droplet contacting region 113 which is greater than the contact angle A(a) produced at the edge of the droplet contacting region 115.
• Equation (3) can be simplified to equation (4):
• the force experienced by a droplet will cause movement in the direction of the surface featuring the higher surface energy in this case towards the core.
• the surface energy gradient or discontinuity has been depicted in Fig. 4 as a single, sharp discontinuity or boundary between well-defined regions of constant but differing surface energy.
• Surface energy gradients may also exist as a continuous gradient or a step-wise gradient, with the force exerted on any particular droplet (or portions of such droplet) being determined by the surface energy at each particular area of droplet contact.
• the term “gradient” when applied to differences in surface energy or work of adhesion is intended to describe a change in surface energy or work of adhesion occurring over a measurable distance.
• discontinuity is intended to refer to a type of “gradient” or transition, wherein the change in surface energy occurs over an essentially zero distance. Accordingly, as used herein all “discontinuities” fall within the definition of "gradient”.
• capillary and “capillarity” are used to refer to passageways, apertures, pores, or spaces within a structure which are capable of fluid transport in accordance with the principles of capillarity generally represented by the Laplace equation (5):
• R is the internal radius of the capillary (capillary radius).
• G and A are as defined above.
• Water is used as a reference liquid throughout only as an example for discussion purposes, and is not meant to be limiting.
• the physical properties of water are well-established, and water is readily available and has generally uniform properties wherever obtained.
• the concepts regarding work of adhesion with respect to water can easily be applied to other fluids such as blood, menses and urine, by taking into account the particular surface tension characteristics of the desired fluid.
• the fluid is more readily retained in the absorbent core due to the driving forces of the surface energy gradients between the backsheet and core.
• the upper and lower bounds of any such gradient are relative with respect to one another, i.e., the regions of the backsheet and core whose interface defines a surface energy gradient need not be on different sides of the hydrophobic/hydrophilic spectrum. That is to say, a gradient may be established by two surfaces of diverse degrees of hydrophobicity or diverse degrees of hydrophilicity, and need not necessarily be established with regard to a hydrophobic surface and a hydrophilic surface.
• the upper surface of the backsheet have a comparatively low surface energy, i.e., that it be generally hydrophobic, in order to maximize the driving force imparted to the incoming fluid from the core and minimize the overall wet through of the backsheet on the garment-contacting surface.
• the surface energy gradients provide a synergistic effect in combination with the one directional fluid transport nature of the backsheet to prevent fluid transport through the backsheet. Fluid on the first surface of the backsheet encounters two differing, but complementary driving forces which oppose its motion away from the core to the backsheet and towards the garment. These two forces likewise combine to oppose fluid movement toward the backsheet, thus dramatically reducing the incidence of wet through.
• a number of physical parameters should be considered in designing an apertured backsheet and a core according to the absorbent article of the present invention, more particulariy with regard to appropriately sizing and positioning the surface energy gradients for proper fluid handling. Such factors include the magnitude of the surface energy differential (which depends upon the materials utilized), migratability of materials, bio-compatibility of materials, porosity or capillary size, overall caliper and geometry, fluid viscosity and surface tension, and the presence or absence of other structures on either side of the interfaces.
• the difference in fluid contact angle between two adjacent surfaces providing a surface energy gradient should be at least 10°, preferably at least 20° and the surface having the lower surface energy should have a fluid contact angle of at least 90°, preferably at least 100°, more preferably at least
• the contact angle of a layer may be increased by rendering that surface more hydrophilic.
• a sheet of polyethylene is extruded onto a drum where it is vacuum formed into an apertured formed film and then, if desired, subjected to a corona discharge treatment generally in accordance with the teachings of U.S. Pat. Nos. 4,351 ,784 issued to Thomas et al. on Sept. 28, 1982; 4,456,570 issued to Thomas et al. on Jun. 26, 1984; and 4,535,020 issued to Thomas et al. on Aug. 13, 1985, the disclosures of each of these patents being inco ⁇ orated herein by reference.
• a surface treatment having a relatively lower surface energy is then applied to the wearer facing surface of the apertured formed film and is preferably cured.
• a suitable surface treatment is a silicone release coating from Dow Corning of Midland, Michigan available as Syl-Off 7677 to which a crosslinker available as Syl-Off 7048 is added in proportions by weight of 100 parts to 10 parts, respectively.
• Another suitable surface treatment is a coating of a UV curable silicone comprising a blend of two silicones commercially available from General Electric Company, Silicone Products Division, of Waterford, NY, under the designations UV 9300 and UV 9380C-D1 , in proportions by weight of 100 parts to 2.5 parts, respectively.
• coating application levels of at least 0.25g, preferably 0.5 to 8.0 grams silicone per square meter of surface area have performed satisfactorily, although other coating levels may prove suitable for certain applications depending upon the nature of the backsheet and the characteristics of the fluid, etc.
• fluorinated materials such as fluoropolymers (e.g., polytetrafluoroethylene (PTFE), commercially available under the trade name TEFLON") and chlorofluoropolymers.
• fluoropolymers e.g., polytetrafluoroethylene (PTFE), commercially available under the trade name TEFLON
• chlorofluoropolymers Other materials which may prove suitable for reduced surface energy include hydrocarbons such as petrolatum, latexes, paraffins, and the like, although silicone materials are presently preferred for use in the absorbent article context for their biocompatibility properties.
• biocompatible is used to refer to materials having a low level of specific adsorption for, or in other words a low affinity for, bio-species or biological materials such as gluco-proteins, blood platelets, and the like.
• Another preferred method for converting a ribbon of polyethylene film into an apertured formed film is by applying a high pressure fluid jet comprised of water or the like against one surface of the film, preferably while applying a vacuum adjacent the opposite surface of the film.
• a high pressure fluid jet comprised of water or the like
• Such methods are described in greater detail in commonly assigned U.S. Pat Nos. 4,609,518 issued to Curro et al. on Sept. 2, 1986; 4,629,643 issued to Curro et al. on Dec. 16, 1986; 4,637,819 issued to Ouellette et al. on Jan. 20, 1987; 4,681 ,793 issued to Unman et al. on July 21 , 1987; 4,695,422 issued to Curro et al. on Sept.
• the apertured formed film may, if desired, be subjected to a corona discharge treatment.
• a silicone release coating may then be applied or printed onto the first surface of the apertured formed film and is preferably cured.
• the surface energy of the silicone-treated surface is less than the surface energy of the untreated surface of the backsheet.
• the layer exhibiting the lower surface energy e.g. the apertured polymeric backsheet layer may have the low surface anergy material inco ⁇ orated within said layer during manufacture such that the layer is rendered hydrophobic during manufacture.
• This layer may then have a low surface energy material applied to its surface.
• said layer comprises at least 5% by total weight of said layer of a low surface energy material.
• the absorbent article is constructed by joining the various elements such as topsheet, backsheet and absorbent core by any means well known in the art.
• the backsheet and/or topsheet may be joined to the absorbent core or to each other by a uniform continuous layer of adhesive, a patterned layer of adhesive, or any array of separate lines, spirals or spots of adhesive.
• the elements may be joined by heat bonds, pressure bonds, ultra sonic bonds, dynamic mechanical bonds or any other suitable joining means known in the art and any combination thereof.
• the absorbent article may find utility in sanitary napkins, panty liners, adult incontinence products and baby diapers.
• the absorbent article may comprise elastic, fastening devices and the like despending on the intended use of the article.
• the present invention finds utility in sanitary napkins and panty liners.
• Absorbent article according to the present invention were prepared as indicated below.
• the backsheets were constructed from the following raw material: a) non-woven fabric 28g/m2 having a spunbonded layer of 14g/m2 and a melt blown layer of 14g/rr>2 obtainable from Corovin GmbH , Peine, Germany under designation MD 2005. b) polyethylene formed film according to US 3 929 135 obtainable from Tredgar Film Products, U.S.A.
• the film has circular shaped apertures with an open area of 19%, an embossed thickness of 0.48mm (funnel height) and an aperture diameter on the garment facing surface of 0.465mm.
• the backsheet was prepared by joining the above described film layer (b) whereby the protruding apertures were orientated towards the wearer facing surface of the absorbent article with the non woven fabric (a) wherein the spun blown becomes the garment facing surface of the absorbent article.
• test sample was prepared under identical conditions in all regards except for the specific treatment applied to material either forming part of or in intimate fluid contact to the backsheet construction.
• sanitary pads produced under the tradename "Always Ultra Normal” available from Procter & Gamble GmbH Schwalbach / Germany were manufactured according to normal manufacturing procedures except for a very low level of attachment of the backsheet to the total structure. This allowed the existing backsheet composed of an impervious (to both liquids and gasses) plastic film to be removed and substituted for an alternative breathable backsheet.
• the structure of the sanitary napkin was identical for all examples except for an additional surface treatment (lowering of the surface energy of one liquid/solid surface via silicone coating).
• the breathable backsheet as described herein above is composed of a uni-directional (one way) conical aperatured film (CPT) made of Low Density PE produced by Tredegar USA under the manufacturing code X-1522 and positioned in contact with the absorbent core composed of tissue and absorbent gelling material.
• CPT conical aperatured film
• the contacting wearer facing surface is composed of a nonwoven laminate manufactured by Corovin GmbH in Germany under the trade name MD 2005.
• the nonwoven laminate is composed of 14 g/m2 spunbond and 14 g/m 2 meltblown. No additional surface treatments have been applied.
• the silicone was manufactured by DOW Corning USA and sold under the trade name SYL-OFF 7048 Crosslinker/SYL-OFF 7677, release coater (mix ratio 10% : 90%).
• aperatured uni ⁇ directional film is made of a blend of Low Density PE (84%) and silicone (16%) and was supplied by Tredegar Film Products B.V. Holland under under request of P & G Pescara Technical Centre S.p.A. The material was produced under comparable conditions to the material manufactured under code X-1522.
• the apertured uni ⁇ directional film is made of high density polyethylene (supplied by Tredegar Film Products, U.S.A., development code 15112).
• the wearer facingr surface 31 (lying in contact with the absorbent core tissue) of the apertured uni-directional film (CPT-HDPE) has been additionally treated with a basis weigth of about 3g/m2 thermally cured silicone.
• the silicone was manufactured by Dow Corning USA (SYL-OFF 7048 Crosslinkers/ SYL-OFF 7677, tradenames, at a ratio of 10%:90%)
• the wet-through test is utilised to evaluate the resistance of a breathable backsheet or backsheet construction to transmission of bodily discharges. It can be used as a direct measure of how liquid-impervious the porous backsheet is to the full range of bodily discharges by simply changing the composition of the test solution as will be detailed following the method description.
• the basic principle of the test is to simulate the loading of a disposable absorbent article in-use with bodily discharges.
• a product is prepared, for example a sanitary napkin, and placed flat on a transparent test stand made of perspex. The product is oriented with the wearer facing surface exposed (upper side) and the backsheet/garment facing surface in contact with the test stand (bottom side).
• a liquid delivery system Suspended above the sample to be analysed is a liquid delivery system that is capable of delivering any desired quantity of the desired test liquid (either as a burst or as a series of steps as is desired).
• a sheet of absorbent filter paper Located between the outer most surface of the test sample and the transparent test stand is a sheet of absorbent filter paper.
• This absorbent filter paper is in intimate contact with the backsheet of the test sample to simulate, for example a sanitary napkin attached to a panty or a diaper/incontinence device in close contact with the clothing.
• a mirror Directly below the transparent test stand is a mirror so positioned to allow any change in the absorbent filter paper (wetting with coloured solutions simulating bodily discharges) to be continuously observed. For example if the porous backsheet is unable to adequately resist liquid transmission then the filter paper will become wet with the coloured solution and this can be observed in the mirror.
• the magnitude of the transmitted solution either as a weight or more preferable the size of the stain on the absorbent filter paper (simulating the panty) in addition to the time dependence of the transmission can be readily recorded.
• test solution is introduced to the test sample via a calibrated delivery system such as via a simple burette according to the desired test approach as detailed below.
• a calibrated delivery system such as via a simple burette according to the desired test approach as detailed below.
• test sample is placed under a pressure of 70 g/c ⁇ 2 (grams per square centimeter) which is believed to reflect more stressful pressures that are nevertheless regularly obtained in-use.
• the test sample remains under the 70 g/cm 2 pressure for a period of up to 30 min. and measurements, for example the area of the coloured stain on the absorbent paper, is measured at 5 minute intervals. It is important to measure over an extended period of time because the mobility of some bodily discharges such as blood or the process of diffusion may be relatively time consuming.
• a breathable backsheet with relatively large apertures is more likely to fail due to a process of extrusion (such as when sitting the pressure exerted may force the liquid through the relatively large apertures) which will happen relatively quickly on placing the test sample under pressure.
• a process of extrusion such as when sitting the pressure exerted may force the liquid through the relatively large apertures
• a process of simple diffusion or capillary driven diffusion is more likely to occur. Such process are slow compared to extrusion processes.
• Test Solution Synthetic Urine + 1% Surfactant or Artificial menstrual fluid + 1% Surfactant
• Method 1b Repetitive Loading Simulation
• the repetitive loading simulation test as performed for a typical sanitary napkin is detailed according to the above general description with the following specific conditions: Specifically the test sample is subjected to a 5 ml load of the test solution (see below) placed in the centre of the test sample. A period of 1 minute allows test liquid to be absorbed and the sample is placed under pressure for 5 minutes. After this period the size (area) of wet-through is measured and recorded. The pressure is immediately removed and the sample is again subjected to a second 5 ml load of test solution.
• the sample (now containing 10 ml of test solution) is placed under pressure for 5 minutes. After this period the size (area) of wet-through is measured and recorded. The pressure is immediately removed and the sample is again subjected to a third 5 ml load of test solution. Again after the 1 min. wait for the liquid to be absorbed the sample (now containing 15 ml of test solution) is placed under pressure for 5 minutes and the stain size (wet-through) is again measured. The cycle is continued until the pad has been loaded to 20 ml.
• Test Solution Synthetic Urine + 1 %Surfactant or artificial menstrual fluid + 1 % surfactant
• Results are reported as area of stain/wet-through in units of square cm (cm 2 ) at loadings of 5, 10, 15 and 20ml.
• test solution type and volumes utilised in the test methods In order to reliabily assess the potential breathable backsheet designs the test solution conditions should be matched to the product end use.
• Sanitary napkins are designed to contain menstrual discharges. These discharges can be quite varied for different women and may contain various levels of fatty acids and detergent type contaminants from daily hygienic practices (washing, laundering etc.). These components are extremely mobile and may have very low surface tensions. It has been determined that actual menstrual discharge behaviour can be simulated using artificial menstrual fluid derived from sheep's blood and mucine with the addition of surfactant as detailed below.
• the volumes of test solutions up to 15 ml for a gush is sufficiently high so that 99% of all in- use gush situations will fall within this range.
• a sanitary napkin in-use may be repetitively loaded up to 20 ml (95 % of all sanitary napkins fall in this range) but seldom higher.
• a sanitary pad will have 10 ml load (90% of all pads) or less.
• incontinence pads, baby diapers or pantiliners pads worn by a woman between the period or at the start/end of the period
• a test solution closer to urine discharges can be used even on sanitary napkins.
• bodily contaminants fatty acids, surfactants and detergent residues
• surfactant to a synthetic urine solution correlates well to conditions found in use.
• feminine hygiene products sanitary napkins, pantiliners
• the volumes again are chosen to reflect typical conditions that this application is likely to expose the products to. For diapers or more stressful incontinence applications the methods can be readily modified to simulate higher test solution loading volumes and rates of delivery.
• test solution Synthetic Urine is first prepared in a 10 kg master batch and smaller quantities are removed as required and surfactant is added.
• Each 10 Kg UreaB batch is composed of the following components: Component: Formula Quantity/1 OKg batch
• reagents are "Reagent Grade” and available from standard Chemical suppliers. Additionally surfactant is supplied by Pegesis, U.S.A. Peosperse 200ML. For individual measurements typically a 100 ml. test solution UreaB/1% Surfactant is prepared by mixing 90 ml. UreaB solution with 10 ml. Surfactant. The UreaB/1% solution must be constantly mixed to ensure the components do not separate prior to usage.
• AMF Artificial Menstrual Fluid
• a surfactant (1%) to this test fluid (supplied by by Pegesis/USA) to better reflect stress situations in which typical hygiene practice (and in some limited situations, dietary influences) may introduce additional surfactants or unexpected levels of, for example, fatty acids, that might lower the blood surface tension.
• Low surface tension menses is the biggest contributor to through backsheet wet-through failure on a breathable absorbent article such as a sanitary article.
• Step 1
• KOH Potassium Hydroxide
• Step 5 Prepare a Mucous Solution by slowly dissolution (with constant stirring) of approximately 30 grams of gastric mucine in the pre-heated (45 ⁇ 5 °C) solution prepared in step 4. Once dissolved the solution temperature should be increased to between 50 - 80 °C and the mixture covered for approximately 15 mins. Turn the heat down to maintain a relatively constant temperature between 40 and 50 °C and continue to stir for a period of 2.5 hrs.
• Step 5 Remove the solution from the hot plate and allow the solution (from step 5) to now cool to less than 40 °C. Add 2.0 ml of the 10% lactic acid solution and mix thoroughly for 2 mins. Step 7: Place the solution in an Autoclave and heat to a temperature of 121 °C for 15 mins.
• AMF test solution with surfactant is prepared by mixing 90 ml AMF solution (maintained at 25 °C) with
• the AMF/1% surfactant solution must be constantly mixed to ensure the components do not separate prior to usage. The solution should be used only within 4 hours of preparation.
• the contact angle test is a standard test to evaluate the nature of the interaction between a solid surface and a liquid droplet.
• the contact angle, a droplet forms on a surface is a reflection of several interactions.
• a droplet on a rough surface typically exhibits a higher contact angle than a droplet on a smooth surface of the same chemical composition. If a droplet of water exhibits a contact angle greater than 90 degrees the surface is considered “hydrophobic" to the liquid. If the contact angle is less than 90 degrees then the surface is deemed “hydrophillic".
• the contact angle a liquid makes on a surface can be measured by a variety of techniques from both optical analysis of a droplet on a surface to more reliable techniques.
• the technique utilised to measure contact angle is the "Wilhelmy Plate Technique". The principal of this technique is to suspend a sample of the solid over a water vessel and slowly lower the sample to a defined depth into the liquid water and then remove it. The retarding force exerted by the water on the material sample on contact (zero immersion depth) is measured by a microbalance and the cosine of the contact angle is then determined from the equation:
• the equipment used to measure the contact angle is a Automated "Dynamic Contact Angle Analyser (model DCA-322)" manufactured by Cahn Instruments, Inc. Cerritos CA 90701-2275 USA.
• a sample 24 mm x 30 mm
• a glass slide as specified in the equipment manual.
• Great care is made to ensure the material sample is not touched that might otherwise contaminate the material surface.
• Each material is measured 5 times to ensure accuracy of measurements and to minimise impact of manufacturing variability or surface irregularities.
• the contact angle of a liquid on a surface and the ability of a porous material to transmit liquids either through capillary or extrusion processes is dependent on surface aberations or surface structure, the nature of the liquid and how it interacts with the surface as well as the mechanism of transport.
• the test solution utilised in this test is distilled water with a high hydrophiiicity and high surface tension. This leads to contact angles that are higher than those typically found or expected to be found with menstrual fluids or urine type discharges. As such the absolute contact results detailed in the table need to be viewed with caution.
• the uni-directional flow test is utilised to quantify the directional flow properties of each surface of an aperatured film to bodily discharges. It can be used as a direct measure of how porous each surface is to the full range of bodily discharges by simply changing the composition of the test soultion as will be detailed following the method description.
• the basic principal of the test is to evaluate the performance of uni ⁇ directional/one way aperatured films to liquids which simulating bodily discharges.
• a "good aperatured film” is a film that shows a distinct preference to fluid transmission from one surface to the other but not in the reverse direction should the film be reversed and the test repeated.
• Naturally a "good aperatured film” will also, in addition to a distinct directionality to fluid transmission, show minimal fluid transmission in direction that would be utilised in the breathable backsheet construction.
• a stack of 10 sheets with dimensions 12 cm x 12 cm of commercially available filter/blotting paper ⁇ produced by Cartiera Favini S.p.A. Italy; Type Abssorbente Bianca "N30" (local vendor Ditta Bragiola SpA. Perugia, Italy) ⁇ are weighed and placed flat the test stand immediately below a suspended weigh.
• a sample each surfaces is 5 labelled arbitrarily surface 1 & 2 of the aperatured film with dimensions 8.5 cm x 8.5 cm to be assessed is placed.
• a layer of fully saturated absorbent material is placed on top of the aperatured film.
• the absorbent material is composed of two sheets of commercially available airlayed absorbent tissue with a basis weight of 63 gsm (each sheet) available from Walkisoft, Denmark under the 0 supplier code Metmar Kotka is utilised to simulate a liquid saturated absorbent core.
• Each sheet of said tissue has dimensions of 5 cm x 5 cm and are placed to lie symmetrically on top of each other.
• the tissue structure is then immersed completely for a period of 1 minute in synthetic urine (see method 1 detailing solutions) to ensure it is fully saturated. 5
• the tissue is removed from the liquid and held in a vertical position for 60 seconds to allow excess fluid to drain before being placed immediately on top of the aperatured film.
• the saturated tissue is placed centrally on the aperatured film that is also positioned centrally on the blotting paper stack.
• a perspex block (dimensions 8.5 cm x 8.5 cm) is placed centrally on top of thew saturated tissue structure and the weight is automatically lowered onto the sample and exerts a pressure of 130 g/cm2 for a period of 60 seconds.
• the lowering of the weight and time is controlled via a simple electronic device to ensure reproduceability from one test to the next.
• the pressure exerted onto the total assembly causes the liquid in the saturated tissue to be extruded onto the film and should the directionality of liquid transmission through the aperatured film be favourable liquid can move through the film and be absorbed by the blotting paper.
• the weight is removed the layers are separated and the blotting paper is inspected for liquid wetting and weighed.
• the weight difference (before/after) is recorded and compared to a second experiment in which the direction of the aperatured film is reversed and the magnitude of test liquid transmitted through the aperatured film in the reverse direction is measured.
• Example aperatured films and alternative materials currently available from a range of companies have been tested and the results are detailed in Table 3.
• Test Solution Urea B/0 % The test solution Synthetic Urine Urea B/0 % is prepared in the same manor as the test solution Urea B/0 % except that no surfactant is added to the test solution.
• a disposable article designed to contain bodily wastes and featuring a breathable backsheet is designed to allow air and water vapour communication with the external environment.
• the extent or efficiency of this process can be linked to the open area of the disposable articles breathable backing and particularly the open area in regions that lie close to the body or where parts of the body are susceptable to occlusion.
• the open area of a permeable backsheet is assessed in terms of both localised levels as well as an averaged level reflecting the total product.
• the open area can be determined for both material(s) that are assembled or combined to form a breathable backsheet construction or for an absorbent articie containing a breathable backsheet or construction.
• the open area calculation for materials is relatively straight forward.
• the material sample is best viewed microscopically and a microscopically expanded image or a still photo should be recorded.
• the image can then be placed on a sheet of mm grid paper to facilitate simple calculation of the number of holes per sqcm and the area of each hole.
• the image can be scanned digitally to determine number of holes and area of holes per sq cm.
• the open area is defined simply as the sum of the areas of each hole divided by the total area under analysis:
• Absorbent articles the open area of an absorbent article containing a breathable backsheet is determined primarily from an assesment of the
• the product is microscopically examined and should regions of differing levels of porosity exist these are quantified and graded. Should regions of differing permeability exist one would typically expect to find usually only regions of some permeability or no permeability. Nevertheless, should this not be the case each region can be marked for later assesment.
• a microscopically expended image or still photo should be taken.
• the image is placed on a sheet of mm grid paper to facilitate simple calculation of are of each hole and to determine the number of holes per sq cm.
• the image can be scanned digitally to determine number of holes and area of holes per sq cm.
• the open are is defined simply as the sum of the area of each hole divided by the total area under analysis:
• the "principal open area” is simply the the regional open area as calculated in Step 2 that occurs in regions of the pad that are anticipated to contribute the most to the benefit of a breathable absorbent article in use. This assesment of principal or secondary region is subjective but can be made in one of two ways:
• Approach 1 The article is worn by a repesentative group of users (for example a woman for a sanitary napkin or light incontinence article) and an assesment is made as to where the article is in close proximity to the body and the potential for occlusion occurs. These are assessed as primary regions and should the backing be porous in any one of these regions they would then be clasified as "principal open area" regions.
• Approach 2 The article is assessed purely technically from a data bank analysis that matches specific article characteristics that will impact pad conformity to the body (measures such as flexibility, article dimensions, thickness etc) to known wearing characteristics. From this purely technical analysis primary or secondary regions can be specified.
• Example aperatured films and alternative materials currently available from a range of companies have been tested and the results are detailed in the table 4.
• the above film is a tri-dimensional film with conical shaped aperature as such there are significant differences in the hole dimensions at each surface.
• Surface 1 is defined as the surface that faces the wearer when used as a breathable backsheet material.

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