CZ205598A3 - Disposable absorption article - Google Patents

Abstract

The present invention relates to a disposable absorbent article (1) comprising a liquid pervious top sheet (2), an absorbent core (4), and a back sheet (3). Said back sheet comprises a fluid permeable polymeric film having uni-directional fluid transfer towards the core, and said core comprising a fluid storage layer, wherein said absorbent article exhibits a fluid contact angle gradient across said storage layer and said back sheet.

Description

Disposable absorbent product

Field of technology

The invention relates to an absorbent product, in particular sanitary pads having a breathable lower layer, which shows reduced wetting (wetting) into the underwear of the user.

Current state of the art

The primary needs of the consumer, which are the starting point for development in the field of absorbent products, especially menstrual products, are. high level of protection and comfort.

One highly desirable means of increasing the comfort of absorbent products is the use of so-called breathable bottom layers. Breathable backsheets may comprise a perforated molded film with directional fluid transfer as disclosed in, for example, US 4,591,523. Such breathable backsheets are typically vapor and air permeable, allowing gas exchange with the outside environment. This allows the evaporation of a part of the fluid stored in the core and increases the circulation of air inside a particular absorbent product. This is particularly beneficial as it reduces the sticky feeling experienced by many wearers, especially during prolonged wear.

However, the main drawback associated with use

- 2 «· ·· ·» ·· application no. disposable breathable lower layers in an absorbent product, there is an increased probability of leakage, commonly called wetting or wetting, into the underwear of the users. Although these breathable underlayers in principle allow only the transfer of gaseous materials and only one-way fluid transfer, physical mechanisms such as extrusion, diffusion and capillary action can still occur and result in the transfer of certain fluids in the opposite direction through this underlayer and on pieces of users' laundry. In particular, these mechanisms become more dominant when a product is used during physical exertion, as a result of loading with heavy discharges or during prolonged wear. Essentially, while breathable bottom layers provide an excellent increase in comfort, they lead to an unacceptable level of failure with respect to protection, especially under stress conditions.

The problem of wetting on pieces of the wearer's underwear as a result of the incorporation of these breathable bottom layers in absorbent products is recognized in the relevant art. Attempts to solve this problem mainly consist of the use of multi-layer bottom layers, such as those shown in US 4,341,216.

Likewise, unpublished European Patent Application No. 94,203,230 discloses breathable absorbent articles comprising a breathable back layer, consisting of at least two breathable layers that are mutually unattached above the core surface. Also unpublished European Patent 94,203,228 discloses a breathable backsheet for absorbent articles comprising an outer layer of gas permeable, hydrophobic, polymeric fibrous material and an inner layer comprising a perforated molded film having directional fluid transfer.

Alternatively, yet another proposed solution to this problem has been to increase the thickness of the absorbent products in question, which is usually achieved by increasing the thickness of the core in order to achieve the desired level of protection.

However, none of the above solutions have proven to be fully satisfactory. This is especially the case with the so-called • · • ·« « ·*· · · * · • 9 999 9 9 99 9999 · • » · *4·· · · · ···· ·· · 9 ·· «· 9 9

- 3 thin products, as thickness is also considered a key variable affecting the comfort of a certain product. Thus, there is such a dichotomy (mutual contradiction.) in the methods used to provide increased comfort in absorbent products that thin breathable products cannot provide the desired level of protection.

As a result, there is a need to provide an absorbent product that offers increased comfort through the use of a breathable back layer and has a reduced thickness that maintains a desired level of protection.

It has now been found that breathable backsheets can be used in thin sanitary napkins to provide both a high level of protection and comfort by creating some hydrophobic (water repellent) gradient between said backsheet and the core, achieved by using a low surface area material. energy such as silicone and chlorofluorocarbons, or treatment with low surface energy. In this way, it is believed, physical mechanisms such as diffusion and capillary action are hindered, and wetting (soaking, seepage) is greatly reduced, if not completely eliminated.

Another advantage of the present invention is that since it allows to provide breathable bottom layers covered with a hydrophobic material, it is no longer necessary for this layer to be completely artificial and can be at least partially derived from a natural material. This provides an important consumer-perceived benefit as the product feels more natural to the touch.

the use of surface energy gradients as such is discussed in unpublished US application number 08/442,935. This discloses fluid transport structures, such as top layers, that exhibit surface energy gradients. The given structure facilitates the transfer of fluid in one direction and resists their transfer in the opposite direction. The structure includes first and second surfaces that are separated from each other by an intermediate portion.

• « · ft • ·

The first surface of this structure has a lower surface energy than the surface energy of a certain intermediate part, thereby creating energy. Suitable materials with low include silicone, fluoropolymers

This structure is particularly suitable as a top layer for absorbent articles, for the purpose of transferring fluid away from (from) the carrier contacting surface into the absorbent structure.

gradient surface surface energy and paraffins.

The essence of the invention

A first aspect of the present invention relates to a disposable absorbent article comprising a fluid permeable top layer, an absorbent core and a bottom layer. The core is placed between the top layer and the bottom layer. The bottom layer includes a fluid permeable polymer film with unidirectional fluid transfer toward the core, the core includes a fluid storage layer, and the bottom layer includes an outer layer. The core and backsheet each include at least one layer, wherein each layer has a wearer-facing surface and a garment-facing surface, and each surface of these layers has some fluid contact angle. The absorbent article has a lower portion extending from and comprising a laundry facing surface of the fluid storage layer and comprising a laundry facing surface of the outer layer.

This invention is characterized by the fact that the wearer-facing surface of at least one of the layers in the lower part has a fluid contact angle greater than the fluid contact angle of the surface of the adjacent layer facing the laundry.

The second aspect of the present invention relates to the situation where the surface of at least one of the layers in the lower part facing the laundry has a contact angle of the fluid greater than the angle of contact of the fluid to the wearer of the facing surface of the same layer.

Another aspect of the present invention relates to the process of manufacturing the absorbent article described above, comprising the step of applying • · · ·

- 5 material with low surface energy on the surface of at least one of the layers in the lower part.

Yet another aspect of the present invention relates to the process of manufacturing an absorbent article described above, comprising the step of incorporating a low surface energy material within one of the bottom layers.

Overview of images on drawings

Giant. 1 - shows a plan view of a first embodiment of an absorbent article of the present invention, with parts cut away to show its assembly.

Giant. 2 - shows an enlarged cross-sectional view of the lower layer of this invention, taken along the line I-I in Fig. 1.

Giant. 3 - shows an enlarged cross-sectional view of a liquid droplet on a surface, where the angle A represents the contact angle of the liquid with this surface.

Giant. 4 - shows an enlarged cross-sectional view of a liquid droplet on a surface having two different surface energies, thus showing two different contact angles A(a) and A{b).

Examples of embodiments of the invention

The present invention relates to disposable absorbent products such as sanitary napkins X, baby diapers, incontinence products and panty covers. These products typically include a fluid-permeable top layer 2, a back layer 3, and an absorbent core 4 that lies between this top layer 2 and the bottom layer 3. The top layer 2, the bottom layer 3, and the core 4 each have a surface facing the wearer's body and a surface facing away from the wearer's body. to the laundry. Surface facing the laundry upper • ···

- The 6 layers and the wearer facing surface of the lower layer are connected to each other on the perimeter 5 of this absorbent product. In a preferred embodiment of the present invention, the absorbent product has wings, side wrapping elements or side flaps.

Absorption core

According to the present invention, the absorbent core comprises a first part and a second part, the first part comprising the following components: (a) an optional primary fluid distribution layer, preferably together with an optional secondary fluid distribution layer; (b) fluid storage layer; and said second portion comprises (c) an optional fibrous (dust) layer underlying the stock layer; and (d) other optional components.

According to the invention, this absorbent core can have any thickness, depending on the intended end use. In a preferred embodiment of the present invention, in which the absorbent product is a sanitary napkin or panty cover, this core can have a thickness of from 15 mm to 1 mm, preferably from 10 mm to 1 mm, and most preferably from 7 mm to 1 mm.

(a) Priming layer/secondary fluid distribution

One optional component of the first part of the absorbent core of the present invention is a primary fluid distribution layer and a secondary fluid distribution layer. The primary fluid distribution layer typically underlies and is in fluid communication with the upper layer. The upper layer transfers the acquired fluid to this primary distribution layer for final distribution to the given storage layer. This transfer of fluid through the layer of primary distribution occurs not only in the thickness, but also along the length and width directions of the given » » v « · * • · • · · · · · · * · · · · · · ··· ·«·· · · · t · · ·· ·« · · · · «·

- 7 absorbent products.

Also optional, but preferred, the secondary fluid distribution layer typically underlies and is in fluid communication with the primary distribution layer. The purpose of this secondary fluid distribution layer is to readily receive fluid from the primary distribution layer and rapidly transfer it to the underlying storage layer. This helps ensure that the fluid capacity of the underlying reservoir layer is fully utilized. The fluid distribution layers may be composed of any material typical of such distribution layers.

(b) Fluid storage layer

The fluid storage layer 6 is placed in fluid communication with, and typically underlies the primary and/or secondary distribution layers. The fluid storage layer may contain any conventional absorbent material or combinations thereof. It preferably contains absorbent gel materials, which are usually referred to in conjunction with suitable carriers as hydrogel, superabsorbent and hydrocolloid materials.

Absorbent gel materials are capable of absorbing large amounts of aqueous body fluids and are further capable of retaining these absorbed fluids under moderate pressures. Absorbent gel materials can be dispersed homogeneously or inhomogeneously in a suitable carrier. These suitable carriers, provided they are absorbent as such, can also be used on their own.

Suitable absorbent gel materials for use herein most commonly comprise a substantially water-insoluble, slightly cross-linked, partially neutralized polymer gel material. This material forms a hydrogel when in contact with water. Such polymeric materials may be prepared from polymerizable, unsaturated acid-containing monomers well known in the art.

• 4 4 ’ ’ ’ * * 4 · t »«l » * ·4 · *4»

4 ··· »4 44 444 4 • 4 » «··· 4*· *444 ·· 44 44 44 44

- 8 Suitable carriers contain materials that are traditionally used in absorbent structures such as natural, modified or synthetic fibers, especially treated or untreated cellulose fibers in the form of fiber fluff and/or tissue paper (or tissue, translation note). Suitable carriers may be used with this absorbent dust material, but these may also be used alone or in combinations. In the context of sanitary napkins and panty covers, tissue paper or its 1aminates are the most preferred.

An embodiment of an absorbent structure made in accordance with the present invention comprises a double layer ε tissue paper laminate formed by folding it back on itself. These layers can be connected to each other, for example, by an adhesive or by mechanical interlocking or hydrogen bonding bands. An absorbent gel material or other optional material may be included between these layers.

Modified cellulose fibers such as reinforced cellulose fibers may also be used. Synthetic fibers may also be used and include those made from cellulose acetate, polyvinyl fluoride, polyvinylidene chloride, acrylics (such as Orion), polyvinyl acetate, insoluble polyvinyl alcohol, polyethylene, polypropylene, polyamides (such as nylon), polyesters, bicomponent fibers, tricomponent fibers, their mixtures and the like. These fibrous surfaces are preferably hydrophilic or are treated to be hydrophilic. The reservoir layer may also contain filler materials such as perlite, diatomaceous earth, vermiculite, etc., to improve fluid retention.

If the absorbent gel material is inhomogeneously dispersed in some carrier, the storage layer may nevertheless be locally homogeneous, i.e., have some gradient of distribution (distribution) in one or several directions within the dimensions of this storage layer. Inhomogeneous distribution can also • · · * • · ·

- 9 refer to carrier laminates, partially or completely encapsulating the given absorbent gel materials.

(c) Optional fiber (dust) layer

An optional component for inclusion in the absorbent core of the present invention is a fibrous layer adjacent to and typically underlying the stock layer. This underlying fibrous layer is typically called a dust (or backfill, note trans.) layer because it provides a substrate (substrate) onto which the absorbent gel material in the stock layer is applied during the production of a particular absorbent core. Indeed, in those cases where the absorbent gel material is in the form of macrostructures such as fibers, layers or strips, this fibrous dust layer may not be contained. However, this dust layer provides some additional fluid handling capacity such as its rapid percolation along the length of the liner.

(d) Other optional absorption structure components

The absorbent core of the present invention may contain other optional components normally present in absorbent structures. For example, inside the respective layers or between the respective layers, a reinforcing mulch can be placed. These reinforcing mules should have such an arrangement (configuration) that they do not create fluid transfer obstacles at the interfaces between the layers. Given that structural integrity usually occurs as a result of thermal bonding, these stiffeners are not usually required for thermally bonded absorbent structures.

rain, one component that may be included in the absorbent core of the present invention and is preferably provided at or as part of the primary or secondary fluid distribution layer is an odor control agent. In the absorbent structure, especially suitable zeolite or aluminum materials covered with active carbon or in addition to other odor control agents are optionally incorporated. These components can be incorporated in any desired form, but are often contained as discrete (fine) particles.

Upper_yr ε t va

The top layer 21 may comprise a single layer or may have multiple layers. In a preferred embodiment, this top layer comprises a first layer 22 which provides a surface of the top layer facing the wearer, and a second layer 23 between this first layer and the absorbent structure/core.

The top layer 21 as a whole, and thus each layer individually, needs to be conformable, soft-feeling and non-irritating to the wearer's skin. This can also have elastic characteristics that allow it to be stretched in one or two directions. According to the present invention, the top layer can be formed from any materials usable for this purpose and known in the relevant art, such as non-woven fabrics, foils or combinations thereof. In a preferred embodiment of the present invention, at least one of these layers (preferably the top) of the top layer includes a fluid-permeable, perforated polymer film 22.

Preferably, this top layer is provided with a foil material having apertures which are provided to facilitate the transfer of fluid from the wearer facing surface towards the respective absorbent structure as detailed in, for example, US 3,929,135, US 4,151,240, US 4 319,868, US 4,324,426, US 4,343,314 and in US 4,591,523.

The top layer typically extends over the entire absorbent structure and may extend into and form part or all of the preferred side flaps, side wrapping elements or ailerons.

• · · to • «« to ·«

- 11 Lower layer

The absorbent articles of the present invention include a breathable backsheet 24 with unidirectional fluid transfer. The primary role of this bottom layer is to prevent exudates absorbed and retained in the given absorbent structure from wetting products that contact a certain absorbent product such as panties, pants, pajamas and underwear components. In addition, however, this lower layer of the present invention also allows the transmission of both steam and air through it and thus allows air to circulate in and out of this lower layer.

The term unidirectional, as used herein, refers to materials having at least substantially, if not significant, unidirectional fluid transfer in the direction of a given core. The direction of the fluid can be determined using test method 3, detailed here in the test methods section.

According to the present invention, the bottom layer preferably comprises at least two layers; a first layer comprising a gas-permeable perforated polymer film 25, and a second layer comprising a gas-permeable layer of fibrous material 26. These first and second layers preferably have a similar (same) relative void volume. Said first layer is typically located adjacent to the core 27 and subsequent layers of this bottom layer are typically located further away from the core. This lower layer may contain additional layers. In all cases, the layer farthest from the core is the outer layer. All these components (layers) of the lower layer can essentially be in close and direct mutual contact.

The perforated first layer of the bottom layer 25 contains a layer having fine holes 28, which extend beyond the horizontal plane to the linen of the turned surface of the given layer towards the core, thus forming protrusions (protuberances) 29. Each of these protrusions has a neck placed on its end. These protuberances preferably have a funnel or conical shape, e * · · · · » · « · ··«« · ··· · · ·· ··· · · · · · · *··« ·« ·· ·♦ ·· ··

- 12 similar to that described in US 3 929 135. The openings located inside the plane of the given layer and the throats located at the ends of these protuberances themselves can be circular or non-circular. In any case, the cross-sectional dimension of the surface of a certain neck at the end of a given protrusion is smaller than the cross-sectional dimension or the area of an opening located inside the plane of the given layer. The first layer of this lower layer typically has an open area greater than 5%, preferably from 10% to 35% of the area of the total foil layer. The open area of this layer can be determined using Test Method #4, detailed herein in the Test Methods section.

According to the present invention, said first layer of the bottom layer 25 may be made of any material known in the art, but is preferably made of commonly used polymer materials.

The second layer of this bottom layer contains a gas-permeable layer of 2jS fibrous material, composed of polymer fibers such as polymer nonwovens known in the relevant art. This fibrous layer preferably has a basis weight of 10 to 100 g/nU, more preferably 15 to 30 g/nU. These fibers can be produced from any polymer material, especially fibers from polyethylene, polypropylene, polyester polyacetate, or their combination (inter- and intra-fibrous combinations) as well as a mixture of synthetic fibers and non-absorbent natural fibers, or treated natural fibers can be used as is cotton. These fibers are preferably non-woven, carded or melt-blown. The second layer preferably contains a matrix of non-woven fibers covered on one side with meltblown fibers or, alternatively, a matrix of meltblown fibers covered on both sides with centrifugally blown fibers. The second layer of the bottom layer may, in addition, contain at least 5% by weight of said layer of fibers which are liquid absorbent such that the fibers swell and reduce the space between the fibers.

The bottom layer typically extends over the whole

A • A

- 13 absorption structure and can extend into and form part or all of preferred side flaps, side wrapping elements or ailerons.

Each fluid of the invention has contact with the wearer's body

According to the first aspect of the present invention, each layer in the lower part has a surface facing the wearer's body and a surface facing the laundry, and each of these surfaces has some fluid contact angle, where the wearer-facing surface of at least one of said layers in the lower part has a greater fluid contact angle than the contact angle of the fluid to the linen of the turned surface adjacent to the linen of the turned surface of the adjacent layer.

According to the second aspect, the layer in the lower part has a surface facing and a surface facing the laundry, and each surface of these layers has some fluid contact angle, where the surface facing the laundry of at least one of said layers in the lower part has a fluid contact angle greater than the contact angle of the fluid to bearers of the turned surface of the same layer.

In principle, some degree of inclination or gradient of contact angle may be present in the lower portion between any surface {wearer-facing or laundry-facing) of any layer therein. Thus, a gradient of contact angle may be present across the wearer- and laundry-facing surface of the same layer or between the laundry-facing surface of at least one layer in the lower portion and the adjacent surface of the adjacent layer, i.e. between the wearer- and laundry-facing surface of the first layer of the lower layer, between to the garment facing surface of the first layer and to the wearer facing surface of the second layer of the bottom layer, between the wearer and the garment facing surface of the second layer of the bottom layer, or between any subsequent layers of the bottom layer. Moreover, it is also predicted that the combination of these layers exhibiting · · • · · · • · · • · * • ••fl ··

- 14 specific relationship of the contact angle will be used, thereby creating a continuous degree of inclination (gradient) in the contact angles in the lower part.

However, for the sake of simplicity, the description of this invention will further focus on the presence of a distinct (different) or increased contact angle gradient between the laundry-facing surface of the core and the wearer-facing surface of the first layer of the underlay.

Typically, a liquid droplet 110 placed on a solid surface 112 forms a contact angle A with that solid surface, as seen in FIG. 3. When the wettability (or wettability) of a solid surface with a given fluid increases, the contact angle A decreases. As the wettability of a solid surface by a given fluid decreases, the contact angle A increases. The fluid/solid contact angle can be determined by techniques known in the art, such as those described in more detail in Physical Chemistry of Surfaces, Second Edition, by Arthur W. Adamson (1967),

F. E. Bartelí and H.H. Zuidema, Journal of the American Chemical Society, 58, 1449 (1936) and J. J. Bikerman, Ind. Eng. Chem., Anal. Ed., 13, 443 (1941). each of which is hereby incorporated by reference. More recent publications in this area include Cheng et al., Colloids and Surfaces 43:151-167 (1990), and Rotenberg et al., Journal of Colloid and Interface Science 93(1):169-183 (1983), which are hereby also incorporated by reference.

As used herein, the term hydrophilic refers to surfaces that are wettable by aqueous fluids (eg, aqueous body fluids) deposited thereon. Hydrophilicity and wettability are typically defined in terms of the contact angle and surface tension of the involved fluids and solid surfaces. This is discussed in detail in the American Chemical Society publication, Contact Angle, Wettability and Adhesion, edited by Robert F. Gould (Copyright 1964), • · · v *

9*0 · * 4 0 0 0 •900·· «0 · · » · · ·

- 15 which is hereby incorporated by reference, we say that a surface is wettable by some aqueous fluid (hydrophilic) when these fluids tend to diffuse spontaneously over the given surface. Accordingly, a surface is considered hydrophobic if aqueous fluids do not tend to diffuse spontaneously across a certain surface.

A particular fluid/solid contact angle depends on surface inhomogeneities (uniformities, e.g., chemical and physical properties such as roughness), contamination, chemical/physical treatment, or composition of a given solid surface, as well as the nature of the particular fluid and its contamination. The surface energy of a particular solid also affects the contact angle. As the surface energy of a solid decreases, the contact angle increases. As the surface energy of a solid increases, the contact angle decreases.

The energy required to separate a liquid from a solid surface (for example foil or fibers) is expressed by the following equation (1):

(1) W = G{1 + cos A) in which:

W -- work of adhesion measured in erg/cm ^a , (xlO ^- --'Jm '')

G ·-- surface tension of the fluid measured in dynes/cm, (x ICPNm ¹ ), a

A = fluid-solid contact angle, in degrees.

For a given fluid, the work of adhesion increases with the cosine of the fluid-solid contact angle (reaching a maximum where the contact angle A is zero).

Work of adhesion is one useful tool for understanding and quantifying the surface energy characteristics of a given surface for any given fluid.

Table 1 is useful to show the interrelationship

- 16 ··· • · · « • · · ···· ** • *0* « · · · » • · · · »· Β • ♦ *» ··· · * • · * ·· ·» between the solid-fluid contact angle and the work of adhesion of a specific fluid (such as water) whose surface tension is 75 dynes/cra ( 75x10 'JM' ').

Table 1

A Jst firmly) cos A; 1 + cos A λ' (erg/cm ··: (xlO ^-3 Jm' ² )

0 1 2 150 30 0.87 1.87 140 60 0.5 1.50 113 90 0 1.00 75 120 -0.5 0.5 38 150 -0.87 0.13 10 180 -1 0 0

As highlighted in Table 1, as the work of adhesion of a particular surface decreases (indicating less surface energy of a particular surface), the contact angle of the fluid on that surface increases and thus the fluid tends to roll up (or intensify upwards, note ) and occupy a smaller contact surface area. The reverse is also true when the surface energy of a given surface decreases with a given fluid. The work of adhesion, therefore, affects the surface (interphase) phenomenon of a fluid on a solid surface.

More importantly, in the context of the present invention, surface energy gradients, as represented by fluid contact angles or discontinuities, have been found to be useful in inhibiting fluid transfer. Giant. 4 shows a fluid droplet 110 placed on a solid surface having two regions 113 and 115 having different surface energies (marked for illustration purposes by different cross-hatching).

• ·

- 17 In the situations shown in Fig. 4. region 113 exhibits a comparatively lower surface energy than does region 115, and thus reduced wettability (wettability) for a fluid droplet than region 115. Accordingly, droplet 110 produces a contact angle A(b) at the edge of the droplet contacting region 113 that is larger than the contact angle A(a) produced at the edge of the droplet contacting region 115. It should be noted that although for graphical clarity the points a" and lie in a plane, the distance dx ¹¹ between points a and b may not be linear, instead representing the extent of droplet/surface contact regardless of the respective shape of the given surface. Droplet 110 therefore experiences a surface energy imbalance and hence an external force due to the differences in relative surface energies (ie, the surface energy gradient or discontinuity) between regions 113 and 1.15, which can be expressed by the following equation (2):

(2) dF = G [cos A(a) - cos A(b)] dx in which:

dF real force on fluid droplet, dx - distance between reference positions a” and ^M b,

G - is defined earlier, and

A(a) and A(b) are the contact angles of A at locations a and b, respectively.

Solving equation (1) for cos A(a) and cos A(b) and substituting into equation (2) gives equation (3):

(3) dF = G [(W(a)/G - 1) - (W(b)/G - 1)] dx

Equation (3) can be simplified to equation (4):

(4) dF ~ (W(a) - (W(b)) dx

- 18 The importance of the respective differential (difference) in surface energy between the two surfaces is clearly highlighted in equation (4), as a directly proportional (proportional) effect that changes in the magnitude of the differential in the work of adhesion it will have on the magnitude of the given force.

A more detailed discussion of the physical nature of the effects of surface energy and capillarity can be found in Textile Science and Technology, Volume 7, Absorbency, ed. Portnoy K. Chatterjee (1985), and in Capillarity, Theory and Practice,

Ind._Eng. Chem., 61.10 (1969) by A.M. Schwartz, which are hereby incorporated by reference.

Accordingly, the force experienced by a droplet will cause movement in the direction of the surface exhibiting higher surface energy, in this case towards the given nucleus. For simplicity and graphic clarity, a certain surface energy gradient or discontinuity was shown in Fig. 4 as a single, sharp discontinuity or boundary between well-defined regions of constant but different surface energy. Surface energy gradients can also exist as a continuous gradient or a step gradient, with the force exerted on a particular droplet (or parts of such a droplet) being determined by the respective surface energy at each particular droplet contact area.

As the term gradient is used herein, when applied to differences in surface energy or work of adhesion, it is intended to describe a change in surface energy or work of adhesion occurring over some measurable distance. The term discontinuity is intended to refer to a type of gradient or transition in which a change in surface energy occurs over essentially zero distance. As used here, all discontinuities fall within the definition of a gradient.

Also, as the terms capillary and capillarity are used here, these refer to passages, openings, pores or gaps within a structure that are capable of transmitting • » • · tt « ·« « » · · « * · tttt·· tttt · « tttt tt·

- 19 fluid in accordance with the principles of capillarity, generally presented

Laplace's equation (5):

(5) ρ = 2G(cos A)/R in which:

p = capillary pressure,

R - the inner radius of the capillary (capillary radius), a

G and A are as defined above.

As noted in Penetration of Fabrics, Emery I. War, in Chapter III of Chem. After treat. Text^ (1971), pages 83-113, which is incorporated herein by reference, for A = 90' ^J the cosine of A is zero and there is no capillary pressure. For A > 90°, the cosine of A is negative and the capillary pressure acts against the entry of the fluid into a certain capillary. Thus, for hydrophilic aqueous fluids, the capillary walls should be hydrophilic in nature for a noteworthy capillary phenomenon to occur. Also, R must be small enough for p to have a significant value, because as R increases (larger hole structure/capillaries), the capillary pressure decreases.

Perhaps at least as important as the presence of surface energy gradients is the specific orientation or location (position) of the gradients themselves with respect to the orientation or location of the capillaries or fluid passages themselves.

Water is used herein as a reference fluid only as an example for the purposes of the discussion, for which it is not intended to be limiting. The physical properties of water are well known and water is readily available and generally has the same properties wherever it is taken. Concepts related to work of adhesion with respect to water can be easily applied to other fluids such as blood, menses and urine by taking into account the special surface tension characteristics of the desired fluid.

By having some surface energy gradient between ft · ft*·· * ··· · ··· · · · · ··· ···· ·· ·· » · ·· ··

- 20 by the core and the bottom layer, creating a relatively low surface energy adjacent to the part of the bottom layer that will be located adjacent to and in contact with the given absorbent core, and the part with a relatively lower surface energy located towards the contact with the wearer's skin, the bottom layer will be able to prevent movement drops of fluid from the core, which has a relatively higher surface energy, to the lower layer, which has a relatively lower surface energy. The movement of the liquid droplet is induced by the difference in the contact angle between the part with lower surface energy and the part with higher surface energy, which leads to an imbalance in the strength of the surface tension acting on the plane of the liquid-solid surface contact. This resulting surface energy gradient, which results in a negative capillary pressure, is believed to be particularly suitable for use with a perforated backsheet on some absorbent article, such as the backsheet 2, 24, on the absorbent article 1.

The potential for backwetting is thereby reduced by having a perforated bottom layer with a surface energy gradient as described above. Since some forces in use tend to force the collected fluid to be squeezed out of the liner (for example, squeezed by the absorbent core being squeezed towards the bottom surface of the backsheet), this unwanted movement will be countered by the backsheet surface, which has a relatively low surface energy, to repel the fluid as this tries to find its way out of the liner through the holes in the bottom layer.

Thus, some fluid is more easily retained in the absorbent core due to the driving forces of the surface energy gradients between the bottom layer and the core.

With respect to the surface energy gradients of the present invention, it is important to note that the upper and lower boundaries of any such gradient are relative to each other, i.e., the respective bottom layer and core regions whose interface defines some surface energy gradient need not be on different sides of the hydrophobic/hydrophilic spectra.

• · · «

- 21 «··· · · ··

That is to say. That a gradient can be created through two surfaces with different degrees of hydrophobicity or different degrees of hydrophilicity, and is not necessarily created with respect to some hydrophobic surface and hydrophilic surface. Notwithstanding the foregoing, it is presently preferred that the top surface of the underlayer have a comparatively low surface energy, i.e., be overall hydrophobic, to maximize the propulsive force imparted to the incoming fluid from the core and to minimize overall wetting by the underlayer to the surface contacting underwear.

Accordingly, in the present invention the surface energy gradients provide a synergistic effect, in conjunction with the unidirectional nature of the underlayer fluid transport, to inhibit fluid transport through the underlayer. The fluid at the first surface of the bottom layer faces two distinct but complementary driving forces that oppose its movement away from the core into the bottom layer and toward the laundry. These two forces similarly combine to counteract the movement of the fluid towards the lower layer, thus dramatically reducing the occurrence of wetting.

A number of physical parameters should be considered in designing the perforated backsheet and core of the absorbent article of the present invention, more specifically with respect to the appropriate sizing and placement of surface energy gradients for proper fluid handling. These factors include the size of the surface energy differential (which depends on the materials used), the ability of the materials to move, the biocompatibility of the materials, the porosity or capillary size, the overall thickness and geometry, the fluid viscosity and surface tension, and the presence or absence of other structures on one side or the other given interfaces.

Preferably, the fluid contact angle difference between two adjacent surfaces providing a surface energy gradient should be at least 10°, preferably at least 20°, and the surface having a lower surface energy should have a fluid contact angle of at least 90°, preferably at least 100°, more preferably at least • · · « · · · · fl surface contact angle more layer shown in Fig. (foil) of polyethylene is al . on September 28, 1982; 4 on June 26, 1984; and 4 cured. relaxing

110°, and most preferably at least 120°.

According to the present invention, some layer can be increased by making it hydrophilic. To make the bottom 2 of the present invention, the sheet is extruded into a drum where it is vacuum formed into an apertured formed film and then, if desired, is subjected to a corona treatment, generally in accordance with the teachings of US Patent Nos.: 4,351 784, issued to Thomas et

456,570, issued to Thomas et al. 535,020, issued to Thomas et al.

on August 13, 1985; the contents of each of these patents are hereby incorporated by reference. A surface treatment with a relatively low surface energy is then applied to the surface of this perforated formed film facing the wearer, and preferably a suitable surface treatment is a silicone surface treatment (paint, packaging, etc., note

trans.) from Dow Corning of Midland, Michigan, available as Syl-Off 7677, to which is added a crosslinker available as Syl-Off 7048 in proportions by weight of 100 parts to 10 parts, respectively. Another suitable surface treatment is a UV (ultraviolet radiation) curable silicone, comprising a mixture of two silicones, commercially available from General Electric Company, Silicone Products Division, of Waterford, NY, under the designations UV 9300 and UV 938O-D1, in weight ratios of 100 parts to 2.5 parts, respectively. When such a mixture is applied to a formed film as shown in FIG. 2, coating application levels of at least 0.25 g, preferably 0.5 to 8.0 grams of silicone per square meter of surface area have worked satisfactorily, although other coating levels may be appropriate for certain applications, depending on the nature of the undercoat and fluid characteristics etc.

Other suitable treatment materials include, but are not limited to, fluorinated materials such as fluoropolymers (eg, polytetrafluoroethylene (PTFE), commercially available under the trade name TEFLON) and chlorofluoropolymers. Other materials that may prove suitable for limited surface energy, latexes, paraffins are preferred for containing hydrocarbons such as petrolatum, and the like, although the use in the context of an absorbent product is silicone materials for their biocompatibility properties. As the term biocompatibility 1 and ta is used herein, it refers to materials having a low level of specific adsorption for, or in other words low affinity for, biospecies or biological materials such as glucoproteins, platelets and the like. As such, these materials tend to resist the deposition of biological material to a greater extent than other materials under user conditions. This property allows them to better retain their surface energy properties as needed for downstream fluid handling situations. In the absence of biocompatibility, the deposition of such biological material tends to increase the roughness or unevenness of the given surface, which leads to increased aerodynamic drag or resistance to fluid movement. Subsequently, biocompatibility also corresponds to a reduced force of aerodynamic resistance or resistance to the movement of the fluid and hence faster access of the fluid to the surface energy gradient and the capillary structure. Maintaining substantially the same surface energy also maintains the original surface energy difference for subsequent or permanent fluid deposits.

However, biocompatibility is not synonymous with low surface energy. Some materials, such as polyurethane, show biocompatibility1 even here to a certain degree, but also show a comparatively high surface energy. At the same time, preferred materials such as silicone and fluorinated materials advantageously exhibit both low surface energy and biocompatibility.

Another preferred method for the conversion (transformation) of the present » ·· • · « · «·

4 ··* ·· · • * · « · · « • 9 9 · ·· · · * ·

- 24 strips of polyethylene film into an apertured (perforated) formed film is applied by means of a nozzle of a high-pressure fluid, composed of water or the like, against one surface of the given film, preferably with the simultaneous use of a vacuum adjacent to the opposite surface of the film. These methods are described in more detail in US Patent Nos.: 4,609,518 issued to Curro et al. on September 2, 1986; 4,629,643, issued to Curro et al. on December 16, 1986; 4,637,819, issued to Quelette et al. on January 20, 1987; 4,681,793, issued to Linman et al. on July 21, 1987; 4,695,422, issued to Curro et al. on September 22, 1987; 4,778,644, issued to Curro et al. on October 18, 1988; 4,839,216, issued to Curro et al. on June 13, 1989; and 4,846,821, issued to Lyons et al. on July 11, 1989; each of these patents is hereby incorporated by reference. This perforated formed film is, if desired, subjected to a corona discharge treatment. A silicone release coating (surface treatment) can then be applied or printed on the first surface of this perforated formed film and is preferably cured. The surface energy of the silicone-treated surface is lower than the surface energy of the untreated surface of the bottom layer.

Alternatively, a lower surface energy layer, for example a perforated polymer back layer, may have a low surface energy material incorporated within the layer during manufacture such that the layer is rendered hydrophobic during manufacture. This layer can then have a material with a low surface energy applied to its surface. Typically, this layer comprises at least 5% of the total weight of said layer of low surface energy material.

According to the present invention, a particular absorbent article is assembled by joining together various elements such as a top layer, a back layer and an absorbent core, by any means known in the art. For example, the bottom layer and/or the top layer can be attached to an absorbent • · «·

- 25 core or to each other with a uniform, continuous layer of adhesive, a patterned layer of adhesive, or any arrangement of separate lines, spirals or points of adhesive. Alternatively, these elements may be joined by thermal bonding, pressure bonding, ultrasonic bonding, dynamic mechanical bonding, or any other suitable bonding means known in the art, and any combination thereof.

According to the present invention, this absorbent product can find its use in sanitary napkins, panty covers, adult incontinence products and baby diapers. Thus, in addition to the components described herein, a given absorbent article may include elastic, fastening devices, and the like, depending on the intended use of the particular article. This invention particularly finds its use in sanitary napkins and panty covers.

- 26 » · · * · · · »·· ·· ♦· *·

Examples:

The absorbent articles of the present invention were prepared as follows:

The lower layers were assembled from the following raw materials:

a) non-woven fabrics 28 g/m'\ having a multi-drawn layer of 14 g/m·- and a melt-blown layer of 14 g/m ² , available from the company Corovin GmbH, Peine, Germany, under the designation MD 2005,

b) polyethylene molded layers according to US 3,929,135, available from Tredegar Film Products, USA. This film has circularly shaped holes with an open area of 19%, an embossed thickness of 0.48 mm (funnel height) and a diameter of the hole on the laundry surface of 0.465 mm.

The bottom layer was prepared by combining the foil layer (b) described above, in which the protruding holes were oriented towards the wearer facing surface of the absorbent article, with a nonwoven fabric (a), in which the meltblown layer becomes the laundry surface of the absorbent article.

Each test sample was prepared under the same conditions in all respects, with the exception of a specific treatment applied to the material either forming the Part or in close contact with the fluid until the assembly of the lower layer. For the test samples, sanitary napkins manufactured under the trade name Always Ultra Normal, available from Procter & Gamble GmbH Schwalbach/Germany, were manufactured according to normal manufacturing procedures, except for a very small level of attachment of the bottom layer to the overall structure. This allowed the bottom layer, composed of an impermeable (both liquid and gas) plastic film, to be removed and replaced with an alternative breathable bottom layer. The assembly of the sanitary pad was identical for all samples, except for an additional surface treatment (reduction of surface energy. one surface liquid/solid • · · · • · · · · · · · · ··«· ·« ·· ·· *· ··

- 27 body through silicone coating),

Example_L·. ( references )

The breathable backsheet as described hereinabove is composed of a unidirectional (one-way) conically perforated sheet (CPT) made of low density PE, manufactured by Tredegar USA under product code X-1522, and placed in contact with an absorbent fabric core. (or tissue paper, note) and absorbent gel material. The contact surface facing the wearer is composed of a non-woven laminate manufactured by Corovin GmbH in Germany under the trade name MD 2005. This non-woven laminate is composed of 14 g/m ² melt blown and .14 g/m^ more drawn (cast or blasted, note transl.) of non-woven material. No additional surface treatments were applied.

Example 2:

The same structure as in Example 1, except that the fabric facing surface 30 of the absorbent core (lying in contact with the wearer facing surface 31 of the perforated unidirectional foil) supplied by Walkisoft, Denmark (material code: Metmar Kotka) has been treated with an area weight of about 6 g/m* ^J heat-cured silicone. The silicone was manufactured by DOW Corning USA and sold under the trade name SYL-OFF 7048 Grossiinker/SYL-OFF 7677, release coating (with a mixture ratio of 10% : 90%).

Example 3:

The same structure as in Example 1, except that the wearer-facing surface 31 (which lies in contact with the ε fabric (tissue) 200 of the absorbent core) is a perforated unidirectional film (C.PT) made of low density PE manufactured by Tredegar USA under production code X-1522, was additionally treated with a basis weight of about 3 g/ni'''' of heat-cured silicone. This silicone was manufactured by DOW Corning USA and sold under the trade name SYL-OFF 7048 Crosslinker/ SYL-OFF 7677, release coating (with a mixture ratio of 10% : 90%).

Example 4:

The same structure as in Example 1, except that the perforated unidirectional film is made of a mixture of low density PE (84%) and silicone (16%) and was supplied by Tredegar Film Products B.V. Holland at the request of P & G Pescara Technical Center S.p.A. The material was produced under comparable conditions to the material produced under code X-1522.

Example 5:

that of Polyethylene Film Products, is to the wearer

The same structure as in Example 3, except that the perforated unidirectional foil (CPT) is made of high density (supplied by Tredegar USA, development code 15112). As in Example 3, the turned surface 31 (which lies in contact with the fabric, tissue, absorbent core) of the perforated one-way film (CPT-HDPE) was additionally treated with a basis weight of about 3 g/m' of heat-cured silicone. This silicone was manufactured by DOW Corning USA (under the trade name SYL-OFF 7048 Crosslinkers/SYL-OFF 7677, in the ratio 10% : 90%).

« · ft ···

- 29 TEST ways

Method No. la & lb Wetting test

This wetting (soaking, seepage) test is used to evaluate the resistance of the construction of a given breathable backsheet or backsheet to the transfer of body exudates. It can be used to directly measure the fluid impermeability of a porous bottom layer to a range of body fluids, simply by varying the composition of a given test solution, as will be detailed following the description of this method.

The basic principle of these methods:

The basic principle of this test is to imitate the loading of a disposable absorbent product with bodily secretions when worn. To achieve this, this product is prepared, such as a sanitary napkin, and placed flat on a translucent test stand made of Plexiglas. This product is oriented with the exposed (top side) surface facing the wearer and the laundry/underlayer facing surface (bottom side) in contact with the test stand. A fluid delivery system is suspended above the sample to be analyzed, which is capable of delivering any desired amount of the desired test fluid (either as a spurt or in a series of steps as desired).

A sheet of absorbent filter paper is placed between the outermost surface of the test specimen and the translucent test stand. This absorbent filter paper is in close contact with the bottom layer of the test sample to simulate, for example, a sanitary napkin attached to panties or a diaper/incontinence device in close contact with clothing. Directly below the given translucent test · 0

0 0 0 • 0 ·« • 00 • · 4 a mirror is placed by the base to enable continuous observation of any change in the absorbent filter paper (moistening by means of colored solutions imitating bodily discharges). For example, if the porous bottom layer cannot adequately resist the transfer of fluid, then the filter paper will become wet with the corresponding colored solution and this can be observed in the mirror. The size of the transferred solution, either as a weight or more preferably the size of a certain smear on absorbent filter paper (mimicking panties), in addition to the time dependence of a given transfer, can be easily recorded.

The test solution is introduced into the test sample via a calibrated delivery system via a simple burette according to the desired test approach as detailed below. Once the given insert has already been loaded (filled) with the given test solution, a period of one (1) minute is allowed for the solution to soak into the test sample so that the upper layer (the surface facing the wearer) is free of puddles of the test liquid.

After this one minute wait, the test specimen is placed under a pressure of 70 g/cnr (grams per square centimeter), which is believed to reflect the higher stress pressures that are nevertheless regularly reached in use. The test sample remains under this pressure of 70 g/cm ² for up to 30 minutes and measurements are taken at 5 minute intervals, for example the area of the color smear on the absorbent paper. It is important to carry out measurements over a longer period of time because the mobility of certain bodily secretions such as blood or the diffusion process can take a relatively certain time.

It is also important to understand the soaking failure mechanism and ensure that a given exact test pattern can properly assess this. For example, a breathable backsheet with relatively large openings (>200 pm) is more likely to fail as a result of the extrusion process (for example, when sitting, the pressure exerted may push the droplet through the relatively large openings).

- 31 which happens relatively quickly when the tested sample is placed under pressure. Alternatively, when these holes are made even smaller (< 200 pm), the process of simple diffusion or capillary driven diffusion is more likely to occur. These processes are slow compared to extrusion processes.

Method la: Imitation of a large eruption

In this first test pattern, the impermeability of the porous bottom layer is measured simulating a high load (sudden turbulent discharge of the test fluid). This user situation is the most difficult to control (it often occurs when standing up after a long period of lying or sitting), because typically the absorbent core (or structure) requires a certain time to function and to adequately absorb and bind body secretions. For example, an absorbent core composed of cellulose fibers (airfelt, tissue paper) and an absorbent gel material requires several minutes before fluids can be adequately absorbed and firmly bound. The unbound fluid, occupying empty or inter-fibrous spaces, is very mobile and can quickly move into the porous lower layer and be pushed out under pressure or transferred through the given lower layer by capillary forces.

The large spill simulation test is performed as detailed in the general description above under the following conditions for a typical sanitary napkin:

test solution: synthetic urine + 1% surfactant or artificial menstrual fluid + 1% surfactant, ejection volume (ml): 10 ml for sanitary napkin, ejection rate (ml/min.) 10 (i.e. 10 ml in 60 seconds), applied pressure: 70 g/cm-'·, (after 1 min. waiting) in » - - ' - * » - - '

Μ· * · ·· · 0*· • » ··· · 0 ·· · · * · · ··· · 0 0 · 000 «««· 0· ·· ·· ·· ··

- 32 Results are reported as smear/wetting area in units of square cm (cm ⁷ ) after 5, 10, and 30 minutes.

Method 1b: Imitation of repeated loading (J_filling)

In this first test pattern, the impermeability of the breathable underlayer is measured under more typical stress conditions, where the excretion of body fluids occurs periodically and in repeated steps, rather than in a single spill event. The repeated loading mimic test, as performed for a typical sanitary napkin, is performed as detailed in the above general description with the following specific conditions: specifically, the test specimen is subjected to a load of 5 ml of the test solution (see below), placed in the center of the tested sample. A 1 minute period allows the test fluid to be absorbed and the sample is placed under pressure for 5 minutes. After this time, the size (area) of wetting is measured and recorded. This pressure is immediately removed and the sample is again subjected to a second loading of 5 ml of the test solution. Again, after waiting 1 minute for the liquid to be absorbed, the sample (now containing 10 ml of test solution) is placed under pressure for 5 minutes. After this period of time, the amount (area) of wetting is measured and recorded. The applied pressure is immediately removed and the sample is again subjected to a third 5 ml load of test solution. Again, after waiting 1 minute for the liquid to be absorbed, the sample (now containing 15 ml of test solution) is placed under pressure for 5 minutes and again the size of the smear (wetting) is measured. This cycle is repeated until the cartridge is loaded (filled) to 20 ml.

test solution: synthetic urine + 1% surfactant or artificial menstrual fluid + 1% surfactant, fefefefe fe ··

- 33 • fe ejection volume (ml):

maximum, load: load rate: (ml/min.) applied pressure: (after 1 min. waiting) repeatedly in doses of 5 ml for sanitary napkin, ml,

2x5 (ie 5 ml in 2 minutes), g/cm ² .

Results are reported as smear/wetting area in units of square cm (tin*') at loadings of 5, 10, 15 and 20 ml.

Type of test solution and volumes used in test methods

In order to reliably evaluate potential breathable backsheet designs, the conditions of the test solution should be matched to the relevant end use of the product. Sanitary napkins are designed to contain menstrual discharge. These excretions can be completely different for different women and can contain different levels of contaminants (pollutants) such as fatty acids and detergent from daily hygiene activities (washing, laundry, etc.). These components are exceptionally mobile and can have very low surface tensions. It has been found that the actual behavior of menstrual fluid can be mimicked by using an artificial menstrual fluid, derived from sheep blood and mucin, with the addition of a surfactant as detailed below. The volumes of test solutions up to 15 ml for spillage are high enough so that 99% of all user fluid spillage situations fall within this range. Similarly, a sanitary napkin can be repeatedly loaded up to 20ml in use (95% of sanitary napkins fall within this range), but rarely higher. A sanitary pad will typically have a load of 10 ml (90% of all pads) or less.

Although incontinence pads, baby diapers, or panty covers (pads worn by a woman between periods or at the start/end of her period) have different requirements than sanitary napkins, the urine-like test solution can also be used on sanitary napkins. However, body contaminants (fatty acids, surfactants, and detergent residues) are still found, and the addition of surfactant to the synthetic urine solution has been determined to correlate well with conditions found in use. As it is common practice to use feminine hygiene products (sanitary pads, panty covers) as a device for light incontinence, it is also appropriate to evaluate the materials of a potential breathable bottom layer or assembly using a solution of synthetic urine containing a surfactant. Again, the volumes are chosen to reflect the typical conditions to which the products are likely to be exposed. For diapers or applications with more severe incontinence, these methods can be easily modified to mimic higher test solution load volumes and delivery rates (doses).

Preparation of synthetic urine test solution + 1% surfactant (UreaB/1%)

The test solution of synthetic urine is first prepared in a 10 kg main batch and smaller amounts are withdrawn as needed and surfactant is added. Each 10 kg dose of UreaB is composed of the following components:

Component:

Formula:

Urea (urea) Sodium chloride Magnesium sulfate Calcium chloride Distilled water

200 g

NaCl

MgSO-i 711^0 CaC 1 :>

Η.Ό g 11 9 g

69 3 g « ft 1 v* · > t · I ftft ftft

All chemical agents (or reagents) are reagent grade and available from standard chemical suppliers. In addition, a surfactant is supplied by Pegesis, USA, Peosperse 2OOML. For individual measurements, typically 100 ml of UreaB/1% surfactant test solution is prepared by mixing 90 ml of UreaB solution with 10 ml of surfactant. The UreaB/1% solution must be constantly stirred to ensure that the components do not separate before use.

Preparation of test solution: artificial menstrual fluid + 1% top reagent

Artificial Menstrual Fluid (AMF) is based on modified sheep blood that has been modified to ensure that it closely resembles human menstrual fluid in viscosity, electrical conductivity, surface tension and appearance. In addition, we introduce a surfactant (1%) into this test fluid (supplied by Pegesis/USA) to better reflect stress situations where typical hygiene practices (and in some limited situations dietary influences) may introduce additional surfactants or unexpected levels, for example, fatty acids that could lower the surface tension of the blood. Menses with low surface tension is the biggest contributor to wetting failure through the bottom layer on a breathable absorbent product such as a sanitary napkin.

Reagent:

1/ defibrinated sheep blood available from Unipath S.p.A (Garbagnate Milanese/Italy).

2/ Lactic acid from J.T. Baker Holland, reagent grade (85-95% w/w).

3/ Potassium hydroxide (KOH) from Sigma Chemical Co., USA, reagent grade.

• «·· • 4» • » *«

4 4* • 4 » · 4 4 · 44 4« 44 *4 - 36 - 4/ Phosphate buffer saline tablets from Co., USA, reagent grade. Sigma Chemical 5/ Sodium chloride from Sigma Chemical Co., USA, reagent quality. 6/ Gastric (stomach) mucin from Sigma Chemical Co., USA, Type III (CAS 84082-64-4). 7/ Distilled water.

Step 1:

Preparation of 9 + 1% lactic acid solution by dissolving lactic acid powder with distilled water.

Step 2j

Preparation of 10% potassium hydroxide (KOH) solution by dissolving KOH powder in distilled water.

Step 3:

Preparation of a phosphate buffer solution adjusted to pH 7.2 by dissolving the tablets according to the instructions in 1 1 of distilled water.

Step 4:

Preparation and slow heating to 45 + 5°C of a solution with the following composition:

o 460 + 5 ml of phosphate buffer solution, o 7.5 + 0.5 ml of KOH solution.

Step 5:

Prepare the mucus solution by slowly dissolving (with constant stirring) approximately 30 grams of gastric mucin in the preheated (45 + 5°C) solution prepared in step 4. Once dissolved, the temperature of this solution should be raised to between 50 - 80 ^<: 'C and the mixture covered for about 15 minutes. Reduce the heat to maintain a fairly constant temperature between 40 and 50°C and continue stirring for 2.5 hours.

in «

- 37 from the hot plate and allowing the solution to now cool to less than 40°C. Add lactic acid and mix thoroughly after 2

Step 6 _: Removal solution (from step 5) To 2.0ml 10% solution I need.y. Kiok 7: Place the solution in for 15 minutes. Step We'll leave it To and dilute in ratio 1

autoclave and heat to a temperature of 121 ^(> C after the solution has cooled to room temperature: 1 using defibrinated sheep blood.

After preparation of the AMF, its viscosity, pil and conductivity are measured to ensure that the characteristics of the blood lie within a range close to normal menstrual blood (see reference H.J. Bussing zu Biochemie de Menstrualblutes, Zb.l Gynaec, 179 456 (1957 ).The viscosity should be in the range of 7 to 8 (cStK units).The corresponding pH should be in the range of 10.5 to 13 (mniho units). above, it should not be used and a new dose of AMF needs to be prepared. This may require adjustment of the amount of gastric mucin used. As it is a natural product, its composition may vary from dose to dose.

For individual measurements, a test solution of 100 mL of AMF with surfactant is typically prepared by mixing a solution of 90 mL of AMF (maintained at 25°C) with 10 mL of surfactant. The AMF/1% surfactant solution must be constantly stirred to ensure that the respective components do not separate before use. This solution should only be used within 4 hours of preparation.

- 38 Method No. 2: Determination of the contact angle of the fluid

The contact angle test is a standard test to evaluate the nature of the interaction between a solid surface and a liquid droplet. This contact angle that the drop forms on the surface is a reflection of several interactions. The nature of the relevant fluid, its surface tension, the nature of the solid and the surface variations, in addition to the nature of the relevant fluid-solid surface interaction. In general, a droplet on some rough surface typically exhibits a larger contact angle than a droplet on a smooth surface of the same chemical composition. If a water droplet has a contact angle greater than 90 degrees, the surface is considered hydrophobic to the particular liquid. If the contact angle is less than 90 degrees, then the surface is considered hydrophilic.

The basic principle of these methods:

The contact angle of a liquid produced on a surface can be measured by a number of techniques, from both optical analysis of the drop on the surface and more reliable techniques. The technique used to measure the contact angle is the Wilhelmy plate technique. The principle of this technique is to suspend a sample of a solid body above a container of water and slowly immerse this sample to a defined depth in the liquid and then remove it. The decelerating force exerted by water on a given material sample upon contact (immersion depth zero) is measured by a microbalance and the cosine of the contact angle is then determined from the following equation (but not in the text, note):

in which:

- 39 F = sample strength at zero immersion depth as determined by weight (mg),

P ~ perimeter of the sample in the interface (cm),

ST - surface tension (dynes/cm)

Cos0 = cosine of the contact angle, g -· acceleration due to the force of gravity (at the measuring location).

The device used to measure the contact angle is an automatic, Dynamic Contact Angle Analyzer (model DCA-322), manufactured by Cahn Instruments, lne. Cerritos CA 90701-2275, USA. For each evaluated material (see Table), a sample (24 mm x 30 mm) is prepared and attached to a glass slide according to the instructions of the manual for this device. Great care is taken not to touch the material of the sample, which could otherwise contaminate the surface of the material. Each material is measured 5 times to ensure measurement accuracy and minimize the impact of manufacturing tolerances or surface irregularities.

t « * * ·· »··· · · · ,... <· »· »· ·· ··

- 40 Table 1:

Surface contact angles (after surface tension-reducing treatment) of commonly available materials were measured.

Example

Surface:

Contact angle untreated

Contact angle treated

AND Fabric (tissue.) core Manufacturer: Walkísoft Denmark Metmar Kotkar zero 131 B LDPE foil, code X-1522 Manufacturer: Tredegar USA 102 121 C LDPE film, code X-1522, both sides treated Manufacturer: Tredegar USA 102 144 D LDPE film, code X-1522 but not perforated: 80 103 Tredegar Film Product B.V. Holland, treat both surfaces. E LDPE + Silicone (8%) foil, (non-perforated): Tredegar Film Product B.V. Holland, treat both surfaces. 92 on F LDPE + Silicone (16%) foil, both surfaces treated: Tredegar Film Product B.V. Hol 1 and 102 on 0 Teflon foil (belt 130 on unpunched) 3M Corp. USA

• 000

- 41 na = unusable, the given material already shows a high contact angle,

LDPE - low density polyethylene (translation note).

The contact angle of a fluid on a surface and the ability of a porous material to transfer fluids either through capillary or extrusion processes is dependent on the surface variations or structure of the surface, the nature of the respective fluid and how it interacts with the given surface, as well as on the given fluid transfer mechanism. The test solution used in this test is distilled water with high hydrophilicity and high surface tension. This results in contact angles that are greater than those typically found or expected to be found in menstrual fluids and/or urine-type discharges.

As such, the absolute contact results detailed in this table should be viewed with caution. A contact angle greater than 90 degrees with water does not mean that the pores of the material will exert a negative capillary force on menstrual-type discharges. However, an increase in contact angle will tend to decrease the extent/efficiency of fluid transfer (either capillary based or extrusion) through the material in question.

»

- 42 Table 2:

Results of pre-humidification testing

Example Solution test Execution test Wetting cm ² untreated Moisturized cm ² treated* 1 UreaB/1% la 41 - AMF/1% la 70 - AMF/1% lbs 90 - 2 UreaB/1% la 41 zero AMF/1% la 70 zero AMF/1% lbs 90 20 3 UreaB/1% la 41 1.3 AMF/1% 1 a 70 16 AMF/1% lbs 90 31 4 UreaB/1% la on 3 AMF/1% la on 11 AMF/1% lbs on 35 5 UreaB/1% la 18 zero AMF/1% la 30 zero AMF/1% lbs 40 7

« *·* · · ·· * · ’’ 4« ·«· · · · * ·· · · *

..·«·*

- 43 Method no__3j - One-way _flow test

The unidirectional flow test is used to quantify the directional flow properties of each perforated foil surface to bodily fluids. It can be used as a direct measure of how porous any surface is to a range of body fluids by simply changing the composition of the test solution, as will be detailed after this method is described.

Basic principle. these ways

The basic principle of this test is to evaluate the performance of one-way/one-way perforated foils against fluids that mimic body fluids. A good perforated film is one that shows a distinct preference for fluid transfer from one surface to another, but not in the reverse direction if the film is reversed and the test repeated. Naturally, a good perforated film, in addition to having distinct directionality to fluid transfer, will also exhibit minimal fluid transfer in the direction used in the construction of a particular breathable backsheet.

In order to evaluate the directional fluid transfer rates of a perforated sheet, a simple test is performed in which a fluid-saturated absorbent structure is placed on top of a certain perforated sheet that rests on top of the edge of an absorbent absorbent paper. Pressure is applied to the entire assembly (saturated absorbent material, foil, and absorbent paper) and the amount of test fluid transferred through a given perforated foil to and absorbed by the absorbent paper is measured. In the second attempt, the direction of the foil is reversed and the attempt is repeated. The amount of fluid transfer through surface 1 and surface 2 is recorded and evaluated.

Specifically, stack 10 layers of 12 cm x 12 cm commercially available filter/absorbent paper (manufactured by Cartiera Favini Sp.A., Italy, type • ·

9t · « ·

- 44 Abssorbente Bianca N30 (local distributor Ditta Bragíola SpA, Perugia, Italy) is weighed and placed flat on the test stand exactly under the suspended weight. A sample (each surface is arbitrarily labeled as surface 1 or 2) of 8.5 cm x 8.5 cm perforated evaluation foil is placed on top of the edge of the absorbent paper. A layer of fully saturated absorbent material is placed on top of the perforated foil. The absorbent material in question is composed of two layers of commercially available air-laid absorbent material (tissue) with a basis weight of 63 g/nu' (each layer), available from Walkisoft, Denmark, under the manufacturer code Metmar Kotka, and is used to mimic liquid-saturated absorbent core. Each layer of this material measures 5 cm x 5 cm and is placed so that it lies symmetrically on top of one another. This material structure is then completely immersed for 1 minute in synthetic urine (see method 1 for details of solutions) to ensure that it is fully saturated.

The material is removed from the fluid and held in a vertical position for 60 seconds to allow excess fluid to drain before being placed immediately on top of the perforated foil. The saturated material is placed centered on this perforated foil, which is also centered on the edge of the absorbent paper.

In the final stage of this test, a Plexiglas block (with dimensions of 8.5 cm x 8.5 cm) is placed centrally on top of the saturated absorbent structure and a weight is automatically lowered onto the sample and exerts a pressure of 130 g/cnď for 60 seconds. The launch of the weight is controlled via a simple electronic device to ensure repeatability from one test to the next.

The pressure exerted on the entire assembly (saturated absorbent material, film and absorbent paper) causes the fluid in the saturated absorbent material to be forced onto (into) the film and if the directionality of fluid transfer through the perforated film is favorable, this fluid should move through the film and be « « * • β •

« ♦ ·

- 45 absorbed by the given absorbent paper. When the weight is removed, the respective layers are separated and the absorbent paper is inspected for fluid wetting (wetting) and weighed. The weight difference (before/after) is recorded and compared ε by a second trial in which the direction of the given perforated foil is reversed and the amount of test fluid transferred by this perforated foil in the reversed direction is measured.

Table 3

Exemplary perforated foils and alternative materials, currently available from a number of companies, were tested and the results are detailed in Table 3.

Material Solution Surface 1 Surface 2 Surface 2 wetting test wetting wetting (treated)

3 g/m ² si1 icon Example 1: CPT (L.DPE), UreaB/0% 2.5 1.8 1.1 manufacturer code: AMF/0% 1.4 0, 8 0.6

X-1522

Tredegar Corp., USA

3 g/m ² silicone Example 2: CPT (HDPE), UreaB/0% 2.3 0.8 0.5 manufacturer code: AMF/0% 1.3 0.5 0.3

X-15112

Tredegate Corpor. USA ft » »ft

ft

46 - 5 g/m² forces icons Example 3: By air UreaB/0% 2.7 2.7 1.1 layered absorp. AMF/O% 1.7 1, 7 0, 8

structure (2 layers, each layer with an area weight of 6 3 g/tn'', manufacturer code: Metmar Kotka, Walkisoft Denmark

Test solutions:

Preparation of test solution Urea B/0%

The test solution of synthetic urine Urea B/0% is prepared in the same way as the test solution Urea B/0% (it should probably be Urea B/1%, note pfekl.) with the exception that no surfactant is added to the test solution.

Way...no . 4: Determining the open ρ 1 mesh

A disposable product designed to contain body exudates and having a breathable bottom layer is designed to allow air and water vapor to communicate with the surrounding environment. The extent of the effectiveness of this process (in terms of consumer benefit) can be associated with the open area of the breathable bottom layer of disposable products and especially the open area in the regions that lie close to the body, or • e»

- 47 where parts of the body are susceptible to occlusion (enclosure or mechanical binding of gaseous substances, translation note). In this test, it is only the open area of the permeable bottom layer that is evaluated in terms of both localized levels and an averaged level reflecting the entire product.

The basic principle of this includes both:

The open area can be determined both for the material(s) that are put together or bonded to form a breathable backsheet assembly or an absorbent article comprising a breathable backsheet or assembly.

Materials: calculating the open area for materials is relatively uncomplicated. A sample of material is best examined microscopically, and a microscopically magnified view of which still photographs should be recorded. This representation should then be placed on a sheet of graph paper to facilitate a simple calculation of the number of holes per square centimeter and the area of each hole. Alternatively, the image can be scanned digitally to determine the number of holes and the area of the holes per square centimeter. The open area is defined simply as the sum of the areas of each opening divided by the total area under analysis.

Absorbent products: the open area of an absorbent product containing some breathable bottom layer is determined primarily from the evaluation of the main open area” in regions expected to contribute to effective connection with the outside environment. Regions of breathability considered to be of little importance are evaluated only as part of the value of the averaged open___area of the total product. For example, in an absorbent product, if breathability is provided in regions not in close contact with, or in regions of the absorbent product that are unlikely to contribute

· • 0«

- 48 to occlusion (closure or mechanical binding of gaseous substances) of the skin, then these should not be evaluated as part of the calculation of the main open area”.

KroJL_lj.

The product is examined microscopically and if there should be different levels of porosity, they are quantified and graded. If there are regions ε differing in permeability, it should typically be expected that usually only regions with a certain permeability or no permeability will be detected. However, should this not be the case, each such region may be flagged for later evaluation.

Step 2:

A microscopically magnified view or still photograph should be taken for each region. This representation is then placed on a sheet of graph paper to facilitate a simple calculation of the area of each hole and to determine the number of holes per square centimeter. Alternatively, the image can be scanned digitally to determine the number of holes and their area per square centimeter. The open area is defined simply as the sum of the areas of each opening divided by the total area under analysis.

This analysis continues for each region with varying porosity or breathability. The value of the averaged open area is then calculated.

Step 3:

The main open____area is simply the regional open area as calculated in Step 2. in the regions of a given insert that are expected to contribute the most to • * · « · 4 · *« 44 4**4 « 4 · · • 4 · · 4 4

- 49 benefits of wearing some breathable absorbent product. This evaluation of the main or secondary region is subjective, but it can be. done in one of two ways:

Approach 1:

The given product is worn by a representative group of users (for example, women in the case of sanitary napkins or a product for small incontinence) and an assessment is made regarding where this product is in close proximity to the wearer's body and the potential for occlusion occurs (enclosure or mechanical binding of gaseous substances) , translation note). These are rated as primary regions and if the backside should be porous in any of these regions, they will then be classified as major open area regions.

Next to t:up 2 :

The given product is evaluated purely technically from the analysis of the data bank, which corresponds to the characteristics of the specific product, which will have an impact on the adaptability of the insert to the body of the wearer (measurements such as flexibility, dimensions of the product, its thickness, etc.) to know the characteristics of wearing. From this purely technical analysis, primary or secondary regions can be specified.

Exemplary perforated foils and alternative materials currently available from a number of companies have been tested and the results are detailed in Table 1ce 4 below.

* ·

- 50 Table 4

Example Material Number of holes Flat hole diam Open area % per cm' 1 CPT (LDPE), 110 manufacturer code: Surface 1 0.43 47 X-1522 Surface 2 0, 13 1 4 Tredegar Corp USA 2 EVA-HEX 99 manufacturer code: Surface 1 0.42 42 4017050 Surface 2 0, 16 16

Tredegar Corp.

USA 3 CPT (HDPE), 110 manufacturer code: Surface 1 0.45 49 X-15112 Tredegar Corp. USA Surface 2 0, 16 18

The foil above is a three-dimensional foil with conically shaped openings, as such it has considerable variation in the dimensions of the openings on each surface. Surface 1 is defined as the surface facing the wearer when a breathable underlayer material is used.

Claims (16)

- 51 - PATENT OVÉ NA YEARS 1. Disposable absorptive product involving liquid they pass top layer, absorptive core and lower layer. The core is placed between the top layer and the bottom layer. The bottom layer includes a fluid permeable polymer film with unidirectional fluid transfer toward the core, the core includes a fluid storage layer, and the bottom layer includes an outer layer, the core and the bottom layer each include at least one layer, where each layer has a surface facing the wearer's body and a surface facing to the laundry, and each of the surfaces of these layers has some fluid contact angle, and this absorbent article has a lower portion extending from and comprising a laundry-facing surface of the fluid reservoir layer and comprising a laundry-facing surface of the outer layer, characterized in that to the wearer, the facing surface of at least one of the layers in said lower part has a fluid contact angle greater than the fluid contact angle of the facing surface of the adjacent layer adjacent to the garment. 2. A disposable absorbent article comprising a fluid permeable top layer, an absorbent core and a bottom layer. The core is placed between the top layer and the bottom layer. The bottom layer includes a fluid-permeable polymer film with unidirectional fluid transfer toward the core, the core includes a fluid storage layer, and the bottom layer includes an outer layer, the core and the bottom layer each include at least one layer, where each layer has a surface facing the wearer's body and a surface facing to the laundry and each of the surfaces of these layers has some fluid contact angle and * 1« 9 9 9 - 52 this absorbent product has a lower part extending from and containing a surface facing the laundry of the fluid storage layer and containing a surface facing the laundry of the outer layer, characterized in that the surface facing the laundry of at least one of the layers in the lower part has a greater fluid contact angle than the contact angle of the fluid to the carrier of the turned surface of the same layer. 3. A method for producing an absorbent product according to claims 1 or 2, comprising the step of applying a material with a low surface energy to the surface of said layer (in the lower part). 4. A method for producing an absorbent product according to claim 1, comprising the step of incorporating a material with a low surface energy inside said layer (in the lower part). 5. A disposable absorbent article according to any one of the preceding claims, wherein at least one of said layers beneath the storage layer comprises a low surface energy material. 6. A disposable absorbent article according to claim 5, wherein said low surface energy material is selected from hard silicones, fluoropolymers, hydrocarbons, or mixtures thereof. 7. A disposable absorbent article according to claim 1, wherein said layer contains at least 5% of the total weight of said layer of low surface energy material. 8. A disposable absorbent article according to any of the preceding claims, wherein either the laundry-facing surface or the wearer-facing surface of said bottom layer comprises at least 0.25 g of low surface energy material per square meter of said surface. • ··· • ·« • fefe ·· · · · fefe · · fefefefe · ·«····« fefe· ···« fefe *· · * ·· · * - 53 A disposable absorbent article according to any of the preceding claims, wherein the bottom layer comprises two layers, a first layer adjacent to the core comprising a polymeric film, and an outer layer comprising a gas permeable layer of fibrous material. 10. A disposable absorbent article according to any of the preceding claims, wherein the core comprises at least two parts, a first part comprising a storage layer and a second part comprising a fibrous layer, the fibrous layer being adjacent to the bottom layer. 11. A disposable absorbent article according to any of the preceding claims, wherein the surface of the layer facing the wearer has a fluid contact angle at least 10° greater than the fluid contact angle of the adjacent surface. 12. Disposable absorbent product according to claim 11, in which the fluid contact angle is at least 20° greater than the fluid contact angle of the adjacent surface. 13. A disposable absorbent article according to claim 2, in which the contact angle of the fluid to the laundry of the turned surface of the storage layer is at least 90°. 14. A disposable absorbent product according to claim 13, in which the fluid contact angle of said surface is at least 100 ^ÍJ . 15. A disposable absorbent product according to claim 1 and 2, in which this absorbent product preferably has a continuous gradient of fluid contact angle in said lower part. 16. A disposable absorbent article according to any one of the preceding claims, wherein the article is a sanitary napkin or a panty cover.