WO2000074740A1

WO2000074740A1 - Personal care products with improved fluid handling properties

Info

Publication number: WO2000074740A1
Application number: PCT/US2000/013001
Authority: WO
Inventors: Michael Allen Daley; David Charles Potts; Jack Nelson Lindon; Crystal Sutphin Leach; Nancy Donaldson Kollin; Arthur Edward Garavaglia
Original assignee: Kimberly-Clark Worldwide, Inc.
Priority date: 1999-06-04
Filing date: 2000-05-12
Publication date: 2000-12-14
Also published as: ZA200109520B

Abstract

A cover sheet for a feminine care product made of a material of which the surface is treated or modified to substantially prevent or delay protein deposition upon contact or interaction with a proteinaceous fluid.

Description

PERSONAL CARE PRODUCTS WITH IMPROVED FLUID HANDLING PROPERTIES

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a top sheet or cover material for absorbent articles including personal care articles such as diapers, training pants, adult incontinence garments, feminine care products such as sanitary pads or napkins, surgical gowns and drapes, absorbent pads and the like. More particularly, this invention relates to surface modification or surface treatments for top sheets or cover materials which can be used to provide a desired combination of fluid handling properties, such as faster fluid intake rates, equivalent or lower fluid retention, equivalent or smaller stain sizes, and balanced rewet compared to conventional materials, or similar or equivalent fluid intake with reduced staining or fluid retention compared to conventional materials.

DESCRIPTION OF PRIOR ART Films have been traditionally used to provide barrier properties in limited use or disposable items. By limited use or disposable, we mean that the product and/or component is used only a small number of times, or possibly only once, before being discarded. Examples of such products include, but are not limited to, surgical and healthcare related products such as surgical drapes and gowns, disposable absorbent pads used, for example in the meat industry, and personal care absorbent products such as diapers, training pants, incontinence garments, sanitary napkins, bandages, wipes and the like. In protective apparel, such as hospital gowns, films are used to prevent cross exchange of microorganisms between the wearer and the patient. Although these films are generally effective barriers with respect to water vapor and the like, they are not aesthetically pleasing because their surfaces are smooth and either feel slick or tacky, and they are visually unappealing, making them less desirable in apparel applications and other uses where they are in contact with human skin. A primary purpose of the film in such laminates is to provide barrier properties. However, there is also a need that such laminates be fluid transmissive so that they can transmit fluids in a direction away from the fluid source. Similar requirements exist for absorbent materials such as absorbent pads used, for example, in the meat industry and absorbent materials used for fenestration reinforcement.

Most personal care absorbent articles include a cover material, sometimes hereinafter referred to as a liner, top sheet layer, body-side liner, or cover sheet, an absorbent core and some type of backing material which is generally liquid impervious to help prevent leakage. The types of cover materials generally fall into two main groups based, at least in part, upon performance and aesthetic preferences. In the area of feminine care and sanitary napkins, the market is polarized into two segments, women who prefer clean and dry apertured film covers and women who prefer soft, cloth-like nonwoven covers. The advantage of apertured film covers for sanitary napkins is that they provide a relatively clean and dry surface as menses or menstrual discharge tends to pass through the apertured film layer and into the interior of the absorbent product. A drawback, however, is that such apertured film layers do not provide the degree of softness and comfort that a nonwoven cover material can provide. An additional drawback is the smooth, slick, noncloth-like feel that is characteristic of many apertured films. Nonwoven-based cover materials, on the other hand, are very soft and cloth-like in feel, but tend to retain more of the menses at or just below the surface of the cover material which, in turn, makes the products suffer from the standpoint of properties such as cleanliness and dryness. The difference in functionality is a direct result of the structure of nonwovens, including small average pore size and nonuniform pore size distribution.

Cover sheet materials are utilized for the transport of bodily fluids into the absorbent core of personal care absorbent articles and, thus, materials used for cover sheet applications must manage distinctly different body excretions, depending upon the application and the product type. Some products must manage fluids, such as urine, while others must manage proteinaceous and viscoelastic fluids such as menstrual discharge and fecal matter. The management of viscoelastic menstrual discharge by cover sheet materials for feminine care products is exacerbated due to the variations in composition and rheology over a broad range of elasticity. Fluid management in feminine care applications requires control of absorption of bodily fluids, control of fluid retention in the cover, control of stain size and intensity, control of rewet of fluid back to the surface, and control of the release of fluid to the absorbent core.

There are generally three major classes of cover systems which have been developed to manage these fluids: nonwovens, apertured films, and composites of films and/or nonwovens. The characteristics of an ideal cover system include the capability of immediate fluid intake, no rewet of fluid back to the surface, no fluid retention in the cover, no staining, and complete desorption of the fluid to the absorbent core. The means for providing these properties to a cover system are based upon tailoring of the structure and surface energy in one or more layers of the cover. However, as in the case of the two main cover material groups as discussed above, where there are tradeoffs between performance and aesthetic preferences, so too are there limits to the extent which these ideal properties can be achieved due to the tradeoffs that exist between attributes. For example, increasing the pore size, permeability, or conductance (permeability/thickness) of a cover material typically improves intake but increases rewet of fluid back to the surface. Similarly, increasing the surface energy of a given structure improves fluid intake but increases fluid retention, staining, and rewet. Numerous prior art references teach means for controlling certain of these cover sheet material characteristics.

A nonwoven web material with improved softness comprising monofilaments or fibers of a thermoplastic material to which a wetting agent such as cationic, anionic, and nonionic surfactants are added is taught by U.S. Patent 4,753,834 to Braun et al. U.S. Patent

5,676,660 to Mukaida et al. teaches an absorbent product comprising a liquid permeable cover sheet, a liquid nonpermeable back sheet, and an absorbent layer disposed therebetween, which absorbent layer comprises a water nonswellable synthetic fiber, alone or in combination with a cellulose fiber, and a water-absorbent resin. Hydrophilic foam compositions comprising the in situ reaction product of an isocyanate-cappedpolyetherprepolymer, a hydrophilic agent capable of absorbing water, and an adjuvant comprising an alcohol, a wetting agent such as Pluronic F68, and water is taught by U.S. Patent 5,064,653 and related U.S. Patent 5,065,752, both to Sessions et al. U.S. Patent 5,112,690 to Cohen et al. teaches a method of treating a low hydrohead fibrous porous web material to increase its retentive wettability in which a surface active agent having a hydrophile-lipophile balance of at least about six is adhered to the low hydrohead fibrous porous web material and a corona discharge equivalent to a charge of at least about 0.6 watt minute per square foot per side of the web material is applied to the surface active agent bearing web material. Treated polymer fabrics having improved wicking/wetting characteristics comprising a hydrophobic polymer fabric treating with a wetting agent is taught by U.S. Patent 5,209,966 to Lange et al., U.S. Patent 5,212,270 to Lai, and U.S. Patent 5,219,644 to Lai et al. U.S. Patent 5,527,534 to Myhling teaches a sponge capable of delivering an active pharmaceutical agent into the vaginal canal during insertion of the sponge, while the sponge is resident in the vagina and during removal from the vagina in which the sponge is a polyurethane foam in which a non-ionic surfactant, such as Pluronic

F68 is used in the polyurethane formulation to provide uniform desired cell structure, density, tensile strength, porosity, and degree of hydrophilicity. None of the prior art addresses a method or means for addressing competing attributes so as to produce and thus approach the properties of an "ideal" cover system. There are several factors which influence the flow of liquids in fibrous structures including the geometry of the pore structure in the fabrics, the nature of the solid surface (surface energy, contact angle), the geometry of the solid surface (surface roughness, grooves, etc.), the chemical/physical treatment of the solid surface, and the chemical nature of the fluid. Surface wettability also plays a critical role in the fluid handling properties of absorbent materials such as those used in personal care absorbent products, healthcare products such as surgical gowns and drapes, and food handling such as absorbent pads for meat packaging. For example, the capillary forces that drive fluid intake and wicking derive from the interfacial free energies at the fluid/air/material interfaces. Wettability is a gauge of the surface free energy of the solid phase. A classic method for measuring the wettability of a surface is the contact angle technique in which a droplet of fluid is placed on a flat surface and the angle at which the droplet intercepts the surface is measured. The equation relating contact angle (θ) to interfacial free energy (g) is known as Young's equation, that is:

where SV, SL, and LV refer to the surface/vapor, surface/liquid and liquid/vapor interfaces, respectively. This equation is true for fluids at equilibrium, that is not moving, on a surface. As fluids move across a surface, the contact angle at the fluid front, known as the advancing contact angle, Q^y, is increased slightly from the equilibrium value and the contact angle at the back edge of the fluid, known as the receding contact angle, Q_REC, is decreased slightly from the equilibrium value.

We have identified four fluid-dependent variables which we believe govern the way in which a proteinaceous fluid such as menses behaves on the cover of a feminine care product. These elements, in conjunction with the size (r) and shape of the pores in the cover material and sublayers, control the intake of fluid through the cover and the removal of fluid from the surface of the cover and down into the absorbent layers. These parameters are: 1) the surface tension of the fluid (γ), 2) the complex viscosity of the fluid (η*), 3) the advancing contact angle (Q_ADV) of the surface, that is the wettability of the surface for the fluid, and 4) the receding contact angle (Θ_REC) of the surface. The relationship between these variables and the capillary forces being generated to move the fluid into or out of the cover material are generally governed by the following proportionality:

_A γ cosθ Δp « η r

Where θ and r are either i) the advancing contact angle and pore size of the cover material for fluid intake into the cover material, or ii) the receding contact angle of the cover material and the pore size of the sublayer material for fluid movement out of the cover and into the underlying absorbent. Thus, for rapid fluid intake, a low contact angle (high wettability) is preferable; and for complete fluid intake (lack of fluid hang-up and minimal staining), a high contact angle (low wettability) is preferable.

As previously indicated, the wettability of a surface is governed by the chemical structure and condition of the surface. When an initial fluid insult contacts and moves into a cover material, the fluid contacts a "dry" surface with wettability controlled by the inherent chemical structure of the surface. For surfaces in contact with fluid or which have had prior fluid contact, the effects of advancing and receding contact angles on fluid movement are often complicated by the fact that these surfaces are altered by the fluid contact. This is particularly true of proteinaceous fluids. For example, changes in the receding contact angle, Θ_REC, can be caused by the removal of fugitive surface treatments responsible for wettability (which could decrease wettability and increase the contact angle) or by responses of the surface to the insult fluid, such as surface hydration and protein deposition (both of which would increase wettability and decrease the contact angle). These effects can take place in the time frame of fractions of a second, as is frequently the case for protein deposition, or many minutes as usually occurs for surface hydration or surfactant coating detachment.

For menses and other blood containing fluids, increases in surface wettability upon fluid contact is a major problem. This is due to protein deposition which occurs on virtually all materials, even highly hydrophobic surfaces such as TEFLON^®. The only surfaces that have been shown to completely block protein absorption are surfaces with covalently attached polyethylene oxide molecules. These surfaces are highly wettable, however, and would promote fluid attachment and staining, even without protein binding.

SUMMARY OF THE INVENTION It is one object of this invention to provide a cover sheet for a personal care absorbent product having reduced surface staining compared to conventional covers. It is another object of this invention to provide a cover sheet for personal care absorbent products having appropriate wettability for efficient fluid intake while inhibiting protein binding, one cause of staining, and the resultant increases in surface wettability.

It is yet another object of this invention to provide a method for determining the combination of cover material characteristic elements necessary to produce a cover material having a desired fluid intake, rewet, fluid retention, staining, and desorption of fluid to an absorbent core of a personal care absorbent product.

These and other objects of this invention are achieved by a cover sheet for an absorbent material, including personal care absorbent products, such as feminine care products, surgical drapes and gowns, absorbent pads and the like comprising a material selected from the group consisting of nonwovens, apertured film, film composites, nonwoven composites, and combinations thereof, which surface of said material is treated or modified to substantially prevent or delay protein deposition upon contact or interaction with a proteinaceous fluid. We have found that, in accordance with one embodiment of this invention, the use of PLURONIC^® surfactant surface coatings provides appropriate wettability for efficient intake while inhibiting protein binding and the resultant increases in surface wettability. These surfactants, available from BASF in Germany, are tri-block copolymers comprising a polypropylene oxide (PPO) center section between symmetrical polyethylene oxide (PEO) sections. Alternatively, a similar product under the name S YNPERONIC^® is available from ICI Americas, Inc. Although the inhibition of protein binding by Pluronic surfactants is known, the mechanism of action is unknown. We believe that the PPO center section binds to the coated surface, allowing the PEO end groups to interact with the contacting solution. These PEO chains are highly hydrophilic and provide few sites for protein attachment. Alternatively, or perhaps additionally, the Pluronic molecules may desorb from the coated surface and interact directly with the protein molecules so as to block them from surface attachment. The nature of Pluronic coatings is such that cover intake structures are provided for an insult fluid that are hydrophilic enough to promote rapid fluid intake while providing and maintaining sufficient surface hydrophobicity to promote effective fluid removal and minimize staining.

While we have found that Pluronics are one type of surface treatment which results in appropriate wettability for efficient fluid intake while inhibiting protein binding and the resultant increases in surface wettability, other types of surface modification treatments may demonstrate similar effects. These include copolymers of ethylene oxide and propylene oxide, surface modifications comprising segments of hydrophilic and hydrophobic regions, surfactants or other treatments which are disposed on a surface to produce hydrophilic and hydrophobic regions, and selectively designed surface chemistries which have architecture at the molecular level such that the presence or absence of a stimuli, such as a fluid, triggers specific groups to emerge to the surface. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and features of this invention will be better understood from the following detailed description taken in conjunction with the drawings wherein: Fig. 1 is a schematic diagram of a rate block apparatus suitable for use in determining fluid intake time of a material or material system.

DESCRIPTION OF PREFERRED EMBODIMENTS

We have found that cover materials for personal care absorbent articles, such as feminine care products, diapers, incontinence garments, and the like may be modified to improve fluid intake and at least one of three incongruous properties, namely cover staining, fluid retention, or rewet of fluid back to the cover material surface. Alternatively, the surface of the cover may be modified to improve staining and fluid retention. In accordance with one embodiment, we have found that cover materials having localized wettability demonstrate little change in fluid intake but provide significant improvements in fluid retention and cover staining. The type of surface modification utilized in accordance with this invention depends upon the structure of the cover material and the presence of any localized wettability.

Three model treatments were selected to demonstrate the advantages of tailoring cover material surface modification in conjunction with cover material structure to provide improved fluid management properties when applied to the cover materials. The three model treatments were commercially obtained from BASF (Germany) and are commercially identified as PLURONIC^® F68, PLURONIC^® F98, and PLURONIC^® F105. The Pluronics are block polymers of polyoxyethylene and polyoxypropylene. These formulations differ in the average molecular weight of the blocks of polyoxyethylene and polyoxypropylene. Presumably, the block size and the ratio of PEO/PPO segments control the protein resistance by modifying surface energy of the cover material as measured by receding and advancing contact angle. For each of the block copolymers, 10 grams of specified Pluronic was separately dissolved into 100 grams of a 90/10 by weight percent mixture of isopropanol/water to produce a 10% solution. Each of these solutions was sprayed onto a substrate until the equilibrium weight of the add-on was 2 wt%. It is conceivable that lower amounts of the surfactant may be applied to obtain similar properties.

DEFINITIONS "Equilibrium" is defined as the weight obtained at a point when the solvent has evaporated, leaving primarily the Pluronic deposited on the surface.

"Substrate" is defined as a polymer, fibrous, porous, or foam-like surface or surfaces where said surfaces form structures. For evaluation of the concept of this invention, four model substrates were chosen which differed in their structures and/or localized surface energy. These substrates consisted of the following: a fibrous web, an apertured film composite, an apertured film composite with localized wettability, and a nonwoven composite.

A "fibrous web" is any material comprising fibrous or fiber-like elements, usually in a random arrangement, joined by bonding points which stabilize the structure providing at least some mechanical integrity, which form at least some small pores throughout the length and width thereof between adjacent fiber-like elements. "Fibrous webs" can refer to spunbond, meltblown, airlaid, bonded carded webs, spunlace, etc. "Spunbond" refers to a nonwoven web produced by melt spinning fibers. To demonstrate the effect of the Pluronic treatment system of this invention on nonwoven or fibrous webs, a spunbond cover comprising a 5 denier per fiber (dpf), 0.4 ounces per square yard (osy) melt spunbond web with a density of 0.042g/cc and a permeability of 1658 Darcys was chosen.

The fibers were formulated as 92% E5D47 (Union Carbide) polypropylene fibers with the addition of 8% titanium dioxide concentrate, termed Ampacet 41438.

"Apertured films" is a generic term referring to any material which contains at least some polymer such as polyethylene, polypropylene, polyester, nylon, polymethacrylic acid, polyethylacrylic acid, etc. and which consists of openings termed apertures or pores. Apertured films include, but are not limited to, those formed from vacuum aperturing, pin aperturing, and slit and stretch aperturing. It may also include nets and foamlike expanded structures.

An "apertured film composite" is a material comprising at least two components, an apertured film and a fibrous material situated below the apertured film or by some means attached to the apertured film. An apertured film composite for a cover material in accordance with one embodiment of this invention, which material was used to evaluate the surfactant treatment system of this invention, comprises a 1.1 mil polyethylene film comprising 94% Rexene 1058 and 6% Ampacet 110359 pin apertured using heat and differential speeds to create an apertured film having a 28% open area and an aperture size of 600 microns laminated to a surge material by means of point bonding. The surge material comprises a 10 dpf, 0.7 osy TABCW having a density of 0.0182 g/cc and a permeability of 15,000 Darcys.

"TABCW" is a lofty nonwoven web created by carding fibers and orienting them into a web. This web is then bonded by moving into a through air dryer. The fibers used in this web comprise a bi-component fiber obtained from Chisso comprising a 50/50 weight percent sheath/core, where the sheath is produced from linear low density polyethylene (LLDPE) and the core comprises polypropylene. To render it wettable, a proprietary surfactant, HR6 was applied by the manufacturer. An "apertured film composite with localized wettability" comprises a cast film of three layers, ABA (30/40/30), wherein the composition of each of layers A is 94% Rexene 1058 and 6% Ampacet 110359 and the composition of layer B is 93% Rexene 1058, 1% 90/10 polyethylene/ Atmer, and 6% Ampacet 110359. In accordance with one embodiment, the film is pin apertured to create an apertured film having 28% open area and an aperture size of 600 microns. The apertured film primarily comprises a top surface which has a lower surface energy than the apertured regions. This apertured material is laminated to a surge material through point bonding, which surge material comprises a 10 dpf, 0.7 osy TABCW having a density of 0.0182 g/cc and a permeability of 15,000 Darcys.

A "nonwoven composite" generally comprises at lease two fibrous materials which are positioned one on top of the other or which are otherwise attached. A cover material comprising a coapertured nonwoven composite was produced from a 3.2 dpf, 0.6 osy spunbond with a density of 0.08 g/cc and a 10 dpf 0.7 osy TABCW with a density of 0.0182 g/cc and a permeability of 15,000 Darcys. The material was then apertured to create a material having an open area of about 17% and an aperture size of 1650 microns. Coapertured refers to the process of putting openings or holes into two or more materials through any number of mechamcal means, such as pin aperturing. In addition, some entanglement or bonding may occur between layers with this process.

"Permeability" (Darcy) is obtained from a measurement of the resistance to flow of liquid by the material. A liquid of known viscosity is forced through the material of a given thickness at a constant flow rate and the resistance to flow, measured as a pressure drop, is monitored. Darcy's Law is used to determine a value for permeability.

"Proteinaceous fluids" refers to a fluid that contains protein or protein breakdown products. For purposes of evaluation of the surfactant treatment system of this invention, a menstrual simulant was utilized which has similar properties to menstrual discharge.

"Menstrual simulant" is a material which simulates the viscoelastic and other properties of menses. To prepare the fluid, blood, such as defibrinated swine blood, is separated by centrifuge at 3000 rpm for 30 minutes, although other methods or speeds and times may be used if effective. The plasma is separated and stored separately, the buffy coat removed and discarded, and the packed red blood cells stored separately as well. Eggs, such as jumbo chicken eggs, are separated, the yoke and chalazae discarded, and the egg white retained. The egg white is separated into thick and thin portions by straining the white through a 1000 micron nylon mesh for about three minutes, and the thinner portion discarded. Alternative mesh sizes may be used, and the time or method may be varied provided the viscosity is at least that required. The thick portion of egg white which was retained on the mesh is collected and drawn into 60 cc syringes which are then placed on a programmable syringe pump and the fluid homogenized by expelling and refilling the contents five times. In our case, the amount of homogenization was controlled by the syringe pump rate of about 100 ml min, and the tubing inside diameter of about 0.12 inches. After homogenizing, the thick egg white has a viscosity of about 20 centipoise at 150 sec-1 and it is then centrifuged to remove debris and air bubbles. After centrifuging, 80 mL of the thick homogenized egg white, which contains ovomucin, is added to a 300 cc FENWAL Transfer Pack using a syringe. Then, 60 cc of the swine plasma is added to the transfer pack. The transfer pack is clamped, all air bubbles removed, and placed in a Stomacher lab blender in which it is blended at normal (or medium) speed for about two minutes. The transfer pack is then removed from the blender, 60 cc of swine red blood cells are added, and the contents mixed by hand kneading for about two minutes, or until the contents appear homogeneous. The final mixture has a red blood cell content of about 30 volume percent and generally is at least within the range of 28-32 volume percent for artificial menses. The amount of egg white is about 40 weight percent.

"Intake" refers to the ability of a cover/absorbent to absorb fluid. In our case, the intake time was used to assess the quality of absorption whereby lower intake times denoted materials capable of rapid absorption and higher intake times denoted materials with poorer absorption. For our work, the intake time was recorded for a known quantity of fluid to absorb into a material.

"Stain" refers to fluid, wet or dry, which is present on the top surface, in, or on the bottom surface of a cover material.

TEST METHODS A. Rate Block Intake Test This test is used to determine the intake time of a known quantity of fluid into a material and or material system. The test apparatus consists of a rate block 10 as shown in Fig. 1. A 4" x 4" piece of absorbent 14 and cover 13 are die cut. The specific covers are described in the specific examples. The absorbent used for these studies was standard and consisted of 250 g/m² airlaid made of 90% Coosa 0054 and 10% HC T-255 binder. The total density for this system was 0.10 g/cc. The cover 13 was placed over the absorbent 14 and the rate block 10 was placed on top of the two materials. 2 mL of a menses simulant was delivered into the test apparatus funnel 11 and a timer started. The fluid moved from the funnel 11 into a channel 12 where it was delivered to the material or material system. The timer was stopped when all the fluid was absorbed into the material or material system as observed from the chamber in the test apparatus. The intake time for a known quantity of known fluid was recorded for a given material or material system. This value is a measure of a material or material systems absorbency. Typically, five to ten repetitions were performed, and average intake time was determined. B. Rewet Test

This test is used to determine the amount of fluid that will come back to the surface when a load is applied. The amount of fluid that comes back through the surface is called the "rewet" value. The more fluid that comes to the surface, the larger the "rewet" value. Lower rewet values are associated with a dryer material and, thus, a dryer product.

In considering rewet, three properties are important: (1) intake, if the material/system does not have good intake then fluid can rewet, (2) ability of absorbent to hold fluid (the more the absorbent holds on to the fluid, the less is available for rewet), and (3) flowback, the more the cover prohibits fluid from coming back through the cover, the lower the rewet. In our case, we evaluated cover systems where the absorbent was maintained constant and, thus, we were only concerned with properties (1) and (3), intake and flowback, respectively.

A 4" x 4" piece of absorbent and cover was die cut. The absorbent used for these studies was standard and consisted of a 250 g/m² airlaid made of 90% Coosa 0054 and 10% HC T-255 binder. The total density for this system was 0.10 g/cc. The cover was placed over the absorbent and the rate block was placed on top of the two materials. In this test, 2 mL of menses simulant are insulted into the rate block apparatus and are allowed to absorb into a 4" x 4" sample of the cover material which is placed on top of a 4" x 4" absorbent piece. The fluid is allowed to interact with the system for one minute and the rate block rests on top of the materials. The material system cover and absorbent are placed onto a bag filled with fluid. A piece of blotter paper is weighed and placed on top of the material system. The bag is traversed vertically until it comes into contact with an acrylic plate above it, thus pressing the whole material system against the plate blotter paper side first. The system is pressed against the acrylic plate until a total pressure of 1 psi is applied. The pressure is held fixed for three minutes, after which the pressure is removed and the blotter paper is weighed. The blotter paper retains any fluid that was transferred to it from the cover/absorbent system. The difference in weight between the original blotter and the blotter after the experiment is known as the "rewet" value. Typically, five to ten repetitions of this test were performed, and average rewet was determined. C. Intake/Staining Test

An intake/staining test was developed which enables the stain size, intensity, and fluid retention in components to be observed with fluid flow rate and pressure. Menses simulant was used as the test fluid. A 4" x 4" piece of absorbent and cover were die cut. The absorbent used for these tests was standard and consisted of a 250 g/m² airlaid made of

90% of Coosa 0054 and 10% HC T-255 binder. The total density for this system was 0.10 g/cc. A material system, cover and core measuring 4" x 4", was placed underneath an acrylic plate with an 1/8 inch diameter hole bored into the center. A piece of 1/8 inch tubing was connected to the hole with a fitting. Menses simulant was delivered to the sample using a syringe pump at a specified rate and for a specified volume. The pump was programmed to deliver a total volume of 1 mL to the samples, where the samples were under pressures of 0 psi, 0.0078 psi, and 0.078 psi. These pressures were applied using a weight which was placed on top of the acrylic plates and distributed evenly. The flow rate of the pump was programmed to deliver fluid at a rate of lmL/sec. The stain size for the cover materials was measured manually, and the amount of fluid in each component of the system was measured by weight before and after absorption of the fluid. The stain intensity was evaluated qualitatively by comparison of samples. Staining information was recorded using a digital camera and could be further analyzed with image analysis.

EXAMPLE 1 Four cover materials as discussed hereinabove, namely a fibrous web, an apertured film composite, an apertured film composite with localized wettability, and a nonwoven composite were created for evaluation with the Pluronic surfactant treatment systems utilized in the cover materials of this invention. Tables 1-4 hereinbelow show the results of intake time (s), rewet (g), stain size (mm²) at low, intermediate, and high pressures, and fluid retention (grams) at low, intermediate, and high pressures for a 5 dpf, 0.4 osy spunbond treated with 0.3% Ahcovel Base N-62 (ICI initial Surfactants, Wilmington, Delaware), Pluronic F68, Pluronic F98, and Pluronic F105. Table 1

As can be seen, the results indicate that not all Pluronics behave similarly. For example, a comparison of material treated with Pluronic F 105 to material treated with a standard treatment, Ahcovel Base N-62, shows that the Pluronic F105 treatment reduces intake time, produces no appreciable difference in rewet, reduces stain size, and reduces fluid retention. Material treated with Pluronic F98, compared to Ahcovel Base N-62, produces no appreciable difference in fluid intake time and rewet, but reduces stain size and fluid retention. Finally, material treated with Pluronic F68, compared to Ahcovel, increases fluid intake time, produces no appreciable difference in rewet, and reduces stain size and fluid retention.

Tables 5-8 show the results of the Rate Block Intake Test, the Rewet Test, and the Intake/Staining Test for apertured film composites treated with Pluronics compared with apertured film composites with no treatment. Again, the results indicate that not all Pluronics behave similarly. Pluromc F105 reduces intake time, overall staining, and fluid retention, but has little effect on rewet. Pluronic F98 has no effect on intake time and rewet, reduces overall staining, and generally reduces fluid retention. The use of Pluronic F68 actually increases intake time and rewet, but generally reduces overall staining and fluid retention.

Table 5

Table 8

Tables 9-12 show the results of the Rate Block Intake Test, the Rewet Test, and the Intake/Stain Test for apertured film composites with localized wettability treated with Pluronics compared to no Pluronics treatment. As can be seen, the material treated with Pluronic F68 shows no appreciable difference in intake time. However, rewet, staining and fluid retention all decreased. Material treated with Pluronic F98 also shows no appreciable difference in intake time and fluid retention compared to material without treatment, but shows a substantial improvement in rewet over both the material with no treatment and the material treated with Pluronic F68. Material treated with Pluronic F105 resulted in reduced rewet and fluid retention and no appreciable difference in fluid intake.

Table 9

Table 11

Finally, Tables 13-16 show a comparison of intake, rewet, stain size, and fluid retention for nonwoven composite materials treated with Pluronics compared to treatment of the spunbond in the nonwoven composite with 0.3% Ahcovel. As can be seen, treatment of the nonwoven composite with Pluronics F105 reduces intake time, staining and fluid retention, but increases rewet. Material treated with Pluromcs F98 reduces intake time while increasing rewet. Fluid retention appears to be essentially unaffected while staining shows marginal increases.

Table 13

Table 15

While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purpose of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.

Claims

WE CLAIM:

1. A cover sheet for a fluid absorbent device comprising: a material selected from the group consisting of nonwovens, apertured film, film composites, nonwoven composites, foam structures, expanded structures, and combinations thereof; and one of a treatment and a modification of a surface of said material, said one of said treatment and said modification one of substantially preventing and substantially delaying protein deposition upon contact or interaction with a proteinaceous fluid.

2. A cover sheet in accordance with Claim 1, wherein said one of said modification and said treatment is selected from the group consisting of surfactants, polymers, copolymers, attached surface moieties, coatings, chemical alterations, and combinations thereof.

3. A cover sheet in accordance with Claim 1, wherein said one of said modification and said treatment comprises at least one of a surfactant and a polymer which forms primarily hydrophilic and hydrophobic regions one of on and proximate said surface.

4. A cover sheet in accordance with Claim 1, wherein said one of said modification and said treatment comprises at least one of a surfactant and a copolymer comprising ethylene oxide and propylene oxide segments.

5. A cover sheet in accordance with Claim 1, wherein said one of said modification and said treatment produces a top surface having regions of different surface energy.

6. A cover sheet in accordance with Claim 1, wherein said one of said modification and said treatment produces a different surface energy in a top surface and a sublayer.

7. A cover sheet in accordance with Claim 1, wherein said one of said modification and said treatment comprises at least one polyoxyethylene-polyoxypropylene- polyoxyethylene tri-block copolymer.

8. A cover sheet in accordance with Claim 1, wherein said one of said modification and said treatment comprises a chemical unit selected from the group consisting of ethylene oxide, propylene oxide and mixtures thereof.

9. A cover sheet in accordance with Claim 1 , wherein said material is a fibrous nonwoven web.

10. A cover sheet in accordance with Claim 9, wherein said fibrous nonwoven web is selected from the group consisting of spunbonds, meltblowns, airlaids, bonded carded web, and spunlace.

11. A cover sheet in accordance with Claim 1 , wherein said material is an apertured film composite.

12. A cover sheet in accordance with Claim 11, wherein said apertured film composite comprises localized wettability.

13. A cover sheet in accordance with Claim 1 , wherein said material is a nonwoven composite.

14. A cover sheet in accordance with Claim 1, wherein said material is an apertured film.

15. A cover sheet in accordance with Claim 1 , wherein said material is one of a foam and an expanded structure.

16. In a fluid absorbent article having a cover sheet material for management of proteinaceous fluids, the improvement comprising: one of a modification and a treatment of a surface of said material, said one of said modification and said freatment one of substantially preventing and delaying protein deposition upon one of contact and interaction with a proteinaceous fluid.

17. A fluid absorbent article in accordance with Claim 16, wherein said one of said modification and said treatment is selected from the group consisting of surfactants, polymers, copolymers, attached surface moieties, coatings, chemical alterations, and combinations thereof.

18. A fluid absorbent article in accordance with Claim 16, wherein said one of said modification and said freatment comprises at least one of a surfactant and a polymer which forms primarily hydrophilic and hydrophobic regions one of on and proximate said surface.

19. A fluid absorbent article in accordance with Claim 16, wherein said one of said modification and said freatment comprises at least one of a surfactant and a copolymer comprising ethylene oxide and propylene oxide segments.

20. A fluid absorbent article in accordance with Claim 16, wherein said one of said modification and said freatment produces a top surface having regions of different surface energy.

21. A fluid absorbent article in accordance with Claim 16, wherein said one of said modification and said treatment produces a different surface energy in a top surface and a sublayer.

22. A fluid absorbent article in accordance with Claim 16, wherein said one of said modification and said treatment comprises at least one polyoxyethylene- polyoxypropylene-polyoxyethylene tri-block copolymer.

23. A fluid absorbent article in accordance with Claim 16, wherein said cover sheet comprises a material selected from the group consisting of a nonwoven, an apertured film, a film composite, a nonwoven composite, foam, expanded structures, and combinations thereof.

24. A fluid absorbent article in accordance with Claim 16, wherein said material is a fibrous nonwoven web.

25. A fluid absorbent article in accordance with Claim 24, wherein said fibrous nonwoven web is selected from the group consisting of spunbonds, meltblowns, airlaids, bonded carded web, and spunlace.

26. A fluid absorbent article in accordance with Claim 16, wherein said material is an apertured film composite.

27. A fluid absorbent article in accordance with Claim 26, wherein said apertured film composite comprises localized wettability.

28. A fluid absorbent article in accordance with Claim 16, wherein said material is a nonwoven composite.

29. A fluid absorbent article in accordance with Claim 16, wherein said material is an apertured film.

30. A personal care absorbent article in accordance with Claim 16, wherein said material is one of a foam and an expanded structure.

31. A method for providing desired combinations of fluid handling properties to a cover sheet for a fluid absorbent article for management of a proteinaceous fluid comprising: one of modifying and treating a surface of said cover sheet, thereby one of substantially preventing and delaying protein deposition upon contact or interaction with a proteinaceous fluid.

32. A method in accordance with Claim 31, wherein said one of said modification and said treatment is selected from the group consisting of surfactants, polymers, copolymers, attached surface moieties, coatings, chemical alterations, and combinations thereof.

33. A method in accordance with Claim 31, wherein said one of said modification and said treatment comprises at least one polyoxyethylene-polyoxypropylene- polyoxyethylene tri-block copolymer.

34. A method in accordance with Claim 31, wherein said cover sheet comprises a material selected from the group consisting of a nonwoven, an apertured film, a film composite, a nonwoven composite, foams, expanded structures, and combinations thereof.

35. A cover sheet for a fluid absorbent article having a desired combination of fluid handling characteristics comprising: a material selected from the group consisting of nonwovens, apertured films, film composites, nonwoven composites, foam structures, expanded structures and combinations thereof; and at least one of a freatment and a modification of a surface of said material, said at least one of said treatment and said modification producing an advancing angle and a receding angle whereby deposition of a protein upon contact or interaction with a proteinaceous fluid is one of substantially prevented and delayed.

36. A cover sheet for a feminine care product comprising: a material selected from the group consisting of nonwovens, apertured film, film composites, nonwoven composites, foam structures, expanded structures, and combinations thereof; and one of a treatment and a modification of a surface of said material, said one of said freatment and said modification one of substantially preventing and substantially delaying protein deposition upon contact or interaction with a proteinaceous fluid.

37. A cover sheet for a surgical gown or drape comprising: a material selected from the group consisting of nonwovens, apertured film, film composites, nonwoven composites, foam structures, expanded structures, and combinations thereof; and one of a treatment and a modification of a surface of said material, said one of said treatment and said modification one of substantially preventing and substantially delaying protein deposition upon contact or interaction with a proteinaceous fluid.