MXPA01002957A - Durably wettable liquid pervious webs prepared using a remote plasma polymerization process - Google Patents

Abstract

Disclosed is a durably wettable, liquid pervious web that is particularly suitable as a topsheet for absorbent articles such as baby and adult diapers and feminine hygiene products. The durably wettable, liquid pervious web is derived from a polymeric film or nonwoven to which is applied a thin organic material onto at least one surface of the starting film or nonwoven. The thin organic coating is in the form of a polymer and is obtained by after-glow (or remote) plasma-induced polymerization of a polymerizable unsaturated compound, preferably a polymerizable vinyl or isopropenyl compound, under specific plasma conditions.

Description

, 'As used herein, the term' macroscopically expanded ', when used to describe the frames, three-dimensional, refers to the frames that have been made to conform to the surface of a three-dimensional structure of formation in such a way that both, of their surfaces exhibit the three-dimensional pattern of the structure or pattern formed that has an inherent three-dimensional pattern that arises from its structure. Regardless of whether the three-dimensional pattern is inherent or is generated by the application of a formation process, the pattern is easily visible to simple view when the perpendicular distension between the observer's eye and the plane of the frame is approximately 12. inches By way of contrast, the term "planar", when used herein to describe polymeric films and nonwoven webs, refers to the overall condition of the web when viewed with the naked eye to a macroscopic scale. In this context, "planar" frames include frames having fine-scale surface aberrations on one or both sides, surface aberrations not being easily visible to the naked eye when the perpendicular distance between the eye of the observer and the plane of the frame is of approximately 12 inches i. ^ greater. * A polymeric grid with three-dimensional openings, macroscopically expanded, which is particularly well suited for transferring the liquid 4 deposited on a surface thereof to its opposite surface subsequently isolating the liquid transferred from the skin of the user is disclosed in the same US Patent No. 3,929,135 issued to Thompso on December 30, 1975, the disclosure of which is incorporated by reference. \ * here. Thompson describes a three-dimensional, macroscopically expanded plot (eg, a top sheet) composed of liquid impervious material, but provist with a pattern of tapered capillaries, the capillaries having a base aperture within - from the plane of the upper sheet and a remote apex opening from the plane of the upper leaf, the apex opening being in intimate contact with the absorbent pad used in the disposable absorbent article. Thompson's top sheet allows for the free transfer of liquids from the user's body to the absorbent element of the device while inhibiting the reverse flow of these liquids. This provides a relatively much more dry surface in contact with the user than what has been previously obtained. Another plastic frame with three-dimensional openings, macroscopically expanded, very suitable for use as a top sheet and absorbent articles, such as sanitary napkins is disclosed in the commonly assigned US Patent No. 4,342,314 issued to Radel et al. On August 3 of 1982, the patent being hereby incorporated by reference herein. The three-dimensional, macroscopically expanded plastic web disclosed in the Radel patent exhibits a fiber-like appearance and tactile impression which has been favorably received by consumers when used as a contact surface with the user. In accordance with the teachings of the patents commonly assigned to Thompson and Radel and others, the plastic wefts of the aforementioned type can be made by applying a pressure to the weft while it is supported on a three dimensional structure until the tram is macroscopically expanded. to comply with the three-dimensional cross section of the formation structure on which this is supported. When the perforation of the three-dimensional, macroscopically expanded frame is desired, the pressure differential is applied until such time as the perforation of the screen in the areas coinciding with the openings in the formation structure has been completed. A process based on liquid, of multiple phases, such as that described in U.S. Patent No. 4,609,518 issued September 2, 1986 Curro et al. (hereinafter referred to as "518" patent), the disclosure of which is incorporated herein by reference, was also developed to provide a film with very small and very large openings immediately adjacent to each other. As the patent discloses, the formation of very small openings (including micro size) in the opposite direction from those formed for large openings impedes the ability of the initially unabsorbed liquid to bypass or leak from the surface of the screen. In this way, the liquid that is not immediately transported through the large openings is restricted from leaking from the surface of the weft, and is subsequently captured through the large openings and is deposited in the core of the article when it is used. the plot as a top sheet material. These small outwardly formed openings also reduce the contact level of the weft / skin and reduce the stiffness of the film, and thus the most comfortable feeling for the user. Users have reported that these top sheets have a smooth silky surface. Alternatively, the '518 patent discloses film where very small openings are formed in the same direction as the macro apertures. Regardless of the means employed for the formation of the opening, where a wettable film material is desired, the above references generally obtain such a structure by treating the surface of the naturally hydrophobic polymeric web with a wetting agent. The surface treatment is generally accomplished either by spraying the surfactant on the surface of the weft by immersing the weft in a bath containing surfactant. Regardless of which of these methods is employed, the surface treatment suffers from the inability to precisely control the location and level of the treatment, as well as the adverse effects caused by the migration of significant amounts of the surfactant agent towards the openings and other components. (For example, the absorbent core when using the film with openings as a top sheet in an absorbent article.) The surface treatment also suffers from the disadvantages that the desirable wetting agents, or surfactants, tend to be entrained on repeated exposure. Therefore, when used as a top sheet in an absorbent article, the treated films lose their ability to transport liquid away from the skin and into the core of the article after repeated wetting. No. 4,535,020, issued to Thomas others on August 13, 1985, deals with some of the problems associated with vacuum formed, surface treatment films, incorporating the hydrophilic surfactant into the polymeric resin prior to extrusion for film formation (referred to herein as "surfactant incorporated in the resin"). , or "RIS"). (See also commonly-assigned United States patent application Serial No. 08 / 713,377, filed September 13, 1996 by Y.P.; U.S. Patent No. 4,923,914 to Nohr et al., issued May 8, 1990; U.S. Patent No. 5,057,262 to Nohr et al., issued October 15, 1991; U.S. Patent No. 5,120,888 to Nohr and another issued June 9, 1992.) In accordance with Thomas's teachings, after extrusion of the resin / surfactant mixture, and subsequent formation of the openings, the incompatible surfactant eventually floats to the surface of the film to provide a durably wetter weft. However, with the surface treatment, the RIS suffers from some degree of carryover of the surfactant agent during use and / or during manufacture, particularly if liquid pressure differentials are used to form the openings in the weft. Also the hydrophilic webs formed using the RIS techniques are not immediately wettable and depend on the relationship between the resin and the surfactant and the environmental conditions, they may not become wettable during periods of finite time. Similarly, when these wefts are used in absorbent articles, there will be some time delay before the surfactant (ie, entrained during use) is filled into the surface of the weft. Notwithstanding the teachings of the related art, there remains a need for a durable, wettable, liquid-permeable weave that offers improved durability after the passage of time and / or after exposure to liquid discharges. These treated webs have particular suitability for use in disposable absorbent structures. There also remains a need for a process that provides such a durable wettable fabric. Accordingly, it is an object of present invention to provide a permanently wettable, liquid permeable web having the improved durability wettability. This durable wettability is achieved by applying a plasma-induced hydrophilic coating on at least one surface of the starting web, to render the resulting treated web durably hydrophilic. In particular, the plasma-induced coating is achieved using a plasma polymerization process of "persistent" or "remote luminescence".

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a durable, wettable, permeable web, which is particularly useful as a top sheet material for absorbent articles. In one aspect, the invention relates to a permanently wettable, liquid-permeable tram, which comprises: (i) an apertured screen selected from the group consisting of polymeric films and non-woven webs; (I) a substantially continuous hydrophilic coating, less than about 2.5 microns thick, on at least one weft surface, wherein the hydrophilic coating is applied to the weft by a remote plasma polymerization process; wherein at least one surface of the liquid-permeable weft, durably wettable, has a post-aging contact angle that is not more than 60 degrees greater than the pre-aging contact angle. In a similar aspect with respect to, at least one surface of the treated web will have a post-wash contact angle that is not more than about 60 degrees greater than the pre-wash contact angle. Preferably, both conditions will exist in a single treated frame. The invention also relates to an absorbent article comprising the liquid permeable, durably wettable top sheet, the top sheet comprising a weft and a hydrophilic coating on at least one surface of the weft, wherein the hydrophilic coating is applied to the weft. plot through a remote plasma polymerization process. In other words, the topsheet of the article comprises the durable, liquid-permeable web of the present invention. Finally, the invention relates to a remote plasma polymerization process to produce the permanently wettable, liquid-permeable webs described herein.

DETAILED DESCRIPTION OF THE INVENTION I. Durable Wettable Permeable Plies As discussed in detail below, the present invention relates to a durable, wettable, liquid permeable weave, which is prepared by applying a hydrophilic coating to a polymeric film or starting nonwoven web, using a radiation healing process. As used herein, the term "weft" refers to a partid substrate (i.e., a polymeric film or nonwoven web) to which the hydrophilic coating is applied. In contrast, the terms "liquid permeable, durably wettable" or "treated weft" refers to the final product, polymeric film or woven weft, having the durable hydrophilic coating. As used herein, the term "liquid permeable" refers to the ability of a treated weft or pattern to transport liquids from a surface of the treated weft or web to the opposite surface of the treated weft or weft in a sufficiently efficient manner. to allow the treated fabric to be used as a component of a disposable article. The wefts may be inherently permeable to the liquid or may be made permeable to the liquid by the application of a processing step, such as perforation. As used herein, the term "substantially continuous" means sufficiently continuous to provide the hydrophilic or wettable properties as defined by the established or claimed contact angle limitations. As used, the terms "hydrophilic" and "wettable" are used interchangeably and refer to surfaces that are wettable by aqueous liquids (eg, aqueous body fluids) deposited on these surfaces. Hydrophilic capacity and wettability are typically defined in terms of the contact angle and surface tension of the liquids and solids involved. This is discussed in detail in the American Chemical Society publication titled Wetting and Adherence Contact Angle, edited by Robert F. Gould (Copyright 1964). A surface is said to be wetted by a liquid (ie, hydrophilic) when either the angle of contact between the liquid and the surface of the weft is less than 90 °, or when the liquid tends to spread spontaneously across the surface of the plot, both conditions usually coexisting. Conversely, a surface is considered to be hydrophobic if the contact angle is greater than 90 ° and the liquid does not spontaneously spread across the surface of the screen In general, the smaller of the contact angle between the surface and the liquid , the most hydrophilic surface. The durable, wettable, permeable webs of the present invention are "durably wettable" in that the hydrophilic character generated by the otherwise more hydrophobic film has been maintained over time and after exposure to liquids. As discussed above, previous approaches to the development of wettable hydrophobic films result in initial improvements in wettability, but suffer from the negative attribute that wettability is lost over time and / or exposure to liquids. Durable mojabiida is described herein in terms of the ability of a liquid permeable web, durably wet (as indicated, also referred to herein as a "treated web" to distinguish it from the initial "web") to retain its wettable character after d aging (referred to as "Post-aging") and / or after exposure to liquids (referred to as "Post-wash"). The methods for measuring the contact angle d Post-aging and the post-wash contact angle are discussed below. As indicated, the durable wettability of the polymeric frames is achieved through the use of a remote plasma process. Although not being bound by theory, it is believed that the typical hydrophilic polymer and surface treated polymer systems, such as corona discharge treatments, go through a process of "hydrophobic recovery". During the hydrophobic recovery process, the wettability of the surface tends to decay over time because thermodynamics favor the exposure of the segments of the molecular chain of minor surface energy at the surface of the polymer. As they age, the hydrophilic molecular segments reorient and embed themselves and expose the hydrophobic segments on the surface of the polymer. If chemical entanglement is induced on the surface of the polymer, entanglement tends to limit the mobility of the polymer chain, significantly encouraging the process of "hydrophobic recovery" and therefore retaining the wettability of the polymer surface during the weather. Since the applicant's invention provides for the chemical entanglement of the polymer, via a remote plasma polymerization process, a permanently wettable, liquid-permeable web can be produced. As used herein, "remote plasma" and "persistent luminescence" each mean that the monomer is injected outside the plasma or plasma luminescence zone and the substrate to be surface treated is placed outside the plasma luminescence , usually below the monomer injection opening. The benefit derived from the placement outside the plasma zone is to avoid the interaction of the monomer molecules with the electrons and ions of the plasma that cause unwanted fragmentation of the monomer. Since electrons and ions are short-lived species, they are confined within the plasma luminescence. As used herein, "plasma zone" and "plasma luminescence" each refer to the volume portion within a chamber, usually between the electrodes, which is significantly brighter than the remaining volume due to visible luminescence . The visible luminescence is produced by the species excited by the plasma that undergo electronic relaxation accompanied by the emission of light. Plasma is often referred to as a fourth state of matter. When energy is applied to a solid (for example, a polymer film), the solid can undergo a transition to the liquid state. If more energy is applied, the liquid becomes a gas. If additional energy of the appropriate type is applied, the gas dissociates and becomes plasma. For the polymerization of plasma to produce a coating on a web, which may also be called "plasma grafting", "plasma deposition" or "plasma coating", a suitable organic monomer or mixture of monomers having polymerizable unsaturated groups it is introduced into the plasma zone of the reactor where it is fragmented and / or activated to form more excited species in addition to the complex mixture of the activated gases of the plasma. The excited species and the monomer fragments recombine by being in contact with the web in an indefinite manner up to a long-defined structure which contains a complex variety of different groups and chemical bonds forming a highly interlaced polymer deposited on the web. If O2, N2 molecules containing oxygen or nitrogen are present, either within the plasma reactor during the plasma coating process, or on the exposure of the plasma-coated substrat to oxygen or to the air subsequent to the plasma process, the Polymeric deposit will include a variety of polar groups. In a plasma technique, which is referred to herein as plasma polymerization "in luminescence" or "direct", the screen to be treated and the monomers that are reacted are located within the plasma zone during the process polymerization. Although this technique has been found useful for preparing durably wet wefts that are useful as top sheets for the absorbent articles (see copending patent application of the United States No. Seri 09/157845, filed September 21, 1998 by YP Lee and others and entitled 'PERMEABLE POLYMERIC SHAPES TO LIQUID, DURADERAMENT MOJABLES), the polymerization within the plasma zone has certain disadvantages. For example, the monomers can be undesirably fragmented before deposition on the film. As such, the use of direct plasma polymerization limits to some extent the monomers that can be used. In contrast, the treated webs of the present invention are prepared using "remote" or "persistent luminescence" plasma polymerization (these terms are used interchangeably herein) and therefore the interest of excess fragmentation is mitigated. Remote plasma polymerization is a process in which the polymerization is carried out in the presence of the plasma, but where the plot as well as the input for the monomer feed is located outside, or away from (typically below), the zone of plasma. Fragmentation of the monomer molecules can be largely avoided in this process, since the monomer does not pass the area of highly reactive plasma gases. As such, certain desirable monomers can be used to form the hydrophilic coating in the present process, while these can not be used when the direct plasma polymerization is employed. With the present process, the structure of the deposited polymer can be controlled within certain limits, undesired erosion of the surface of the susceptible substrates can be prevented and the formation of the polymer deposits is predominantly based on the radical reactions. Plasma exists in a variety of ways. The preferred plasm process useful here is a low pressure or vacuum, remote process, which allows the processing of the screen at or near room temperature, i.e., about 20 ° C. This prevents the thermal degradation of the weft that is processed and / or the thermal distortion of the formed web that is being treated. Dentr of the plasma chamber active species in the form of electrons, free radicals, ions and energetic neutrons collide with the surface of the frame, for example, polymer, (which is placed outside the plasma chamber) breaking the molecular bonds and creating new functional groups on the surface of the frame. This active and energetic species also react in the gaseous phase, resulting in a thin coating deposited on at least one surface of the weft.

Plasma systems suitable for use in the present invention incorporate a parallel plate electrode design in which the materials to be treated are exposed to the primary field of RF energy, but are not part of the circuitry. With higher pressure processes (but still within the general definition of a cold gas plasma), it forms some of the gas supply system, designed to create a uniform laminar flow of process gas through the total volume of the chamber. which is beneficial. In multiple electrode / frame designs, it is important that one of the electrodes receives equal amounts of RF energy. In this way s creates a uniform luminescent discharge between each frame or in each plasma zone. The solid state components and the microprocessor control of the system parameters of the process time, flow rate, power level, and working pressure, will also ensure the uniformity, efficiency and repeatability of the process. Since plasmas are electrically conductive atmospheres, they carry a characteristic impedance at the output of the RF generator. Therefore, the preferred plasma process uses an equalization network to constantly tune the plasma impedance to the output impedance of the RF generator. Advanced plasma systems suitable for use in the present invention are available from HIMONT Plasma Science, Foster City, Calif. (a business unit of HIMONT U.S.A., Inc.), and incorporates a type of automatic network equalization provisions for the verification of errors during the process. The low temperature plasma is generated in a gaseous atmosphere reduced pressure from about 0.001 to about 10 Torr, preferably from about 0.01 to about 5 Torr, more preferably from about 0.05 to about 1 Torr, and most preferably from about 0.05 to about 0.4 Torr. The electrical power can be supplied to the equipment at a high radio frequency, of about 40 KHz about 3 GHz, preferably about 13 to about 27 MHz, and very conveniently at about 14 MHz. To achieve the desired plasma condition in the gaseous atmosphere, the electric power supplied to the apparatus may vary over a range of about 1 to about 10,600 watts; preferably from about 10 to about 1,000 watts, more preferably from about 50 to about 500 watts, most preferably from about 75 to about 250 watts. The energy used is a little dependent on the working volume of the camera. The highly preferred range of about 75 to about 250 watts is appropriate for the HIMONT Plasma Science PSS0500D plasma gas apparatus with a workload of approximately 5.0 cubic feet. The plasma treatment time varies from a few seconds to several minutes, preferably from about 20 seconds to about 30 minutes, most preferably from about 60 seconds to about 20 minutes. It should be appreciated that the pressure, time and energy of treatment are interrelated, instead of being independent variables. The effect of the selected level for each of these variables will determine the extent of the modification of the surface of the weft and / or the thickness of the covering; Also related are the volume and geometry of the camera as well as the size of the sample and the geometry of the surface. The selection of the level for these variables is also within the ordinary experience of the practitioners in the art to which this invention pertains. The hydrophilic coating layer is deposited on the surface of a suitable weft (either previously perforated or without openings) by vapor deposition induced by remote plasma (i.e., polymerization) of a monomer or a combination of monomers, such that a hydrophilic coating will be applied to the web. The monomer (s) that can be used to prepare the coatings can be any unsaturated polymerizable compound that can be evaporated and introduced into the persistent luminescence zone of a plasma generating apparatus to make contact with the web provided therein. Preferred monomers are vinyl compounds, including but not limited to: a) acrylic and methacrylic acid of the general formula H2C = C (R2) -C (O) OH, b) acrylates and methacrylates of the general formula H2C = C (R2) -C (O) OR 3, c) acrylamides and methacrylamides of the general formula (R 2) (R 2) C = C (R 2) -C (O) NHR 3, d) maleic acid y-fumaric of the general formula HO (O) C- C (R2) = C (R2) -C (O) OH, e) maleates and fumarates of the general formula R3O (O) C- C (R2) = C (R2) C (O) OR3 , f) vinyl ethers of the general formula (R2) (R2) C = C (R2) -O-R3, g) N-vinyl-2-pyrroidone of the formula (2) (R2) C = C (R2) -N-CH2-CH CH2-C ( h) vinyl acetate of the general formula (R2) (R2) C = C (R2) -OC (O) CH3, and i) aliphatic vinyl compounds of the general formula R2CH = CHR3, and mixtures thereof, wherein each R2 is independently hydrogen or C10 alkyl, preferably CrC5 alkyl, and each R3 is independently an aliphatic hydrocarbon group of up to about 10 carbon atoms which is substituted or unsubstituted by one or more polar groups such as carboxy, hydroxy , amino, and an oxide group ".,to! ? '(poly) ethylene or substituted by one or more sulphates, phosphates, sulfonate groups or mixtures of these groups. Specific examples of the preferred acrylic derivatives include acrylic acid, methacrylic acid, hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA), dimethylaminoethyl methacrylate (DMAEMA), 2-hydroethylacrylate (HEA), N, N-dimethylacrylamide (DMA), N-acryloylmorpholine ( NAM) and ethylene glycol dimethacrylate (EGDMA). Specific examples of the suitable vinyl ethers are methylvinyl ethers, ethylvinyl ether and methoxyethylvinyl meter. Suitable hydrophilic monomers also include ethylene glycol, ethylene oxide and propylene oxide. The monomers can be used individually or as a mixture of monomers. Before being introduced into the chamber, the monomer is heated to a temperature sufficient to vaporize the compound and create sufficient vapor pressure such that the coating is deposited at a reasonable rate. Typically, the temperature will be from about 40 ° to about 100 ° C, more typically from about 40 ° to about 60 °. The oxygen in gaseous form and the argon are fed into the deposition chamber simultaneously with, but each with a separate feed medium and mass flow control, the gaseous compound of the monomer. Depending on the application, the O2 flow rate varies from about 5 standard cubic centimeters / minut ("sccm") to about 1200 sccm, the flow of the gaseous monomer compound from about 1 sccm to about 250 sccm, and the flow of Ar is from about 1 sccm to about 150 sccm. Argon is used to increase the rate of deposition of the gaseous materials that are used and, therefore, it is preferable to use argon in the process. Alternatively, monomer deposition can be achieved via the flash technique described in U.S. Patent No. 4,842,893 issued to Yializis on April 29, 1988, the disclosure of which is incorporated by reference here. The low temperature plasma is generated in a gaseous atmosphere at reduced pressure from about 0.0014 to about 10 Torr, preferably from about 0.01 to about 5 Torr, most preferably from about 0.05 Torr to about 0.4 Torr, depending on the process used and the plot that is treated. With respect to the starting grid, the web can be flat (two dimensions) or complex (three-dimensional, including pre-punched films and non-woven materials) before the plasma deposition of the hydrophilic coating. That is, the plasma treatment can be conducted either before or after the formation of the weft openings. In a preferred embodiment, the plasma treatment will be conducted after the formation of the openings, in order to preserve a uniform hydrophilic coating on the surface of the weft. The aforementioned advanced plasma systems available from HIMONT Plasma Science, such as the PS0500D reactor are equipped with a throttle valve, in this way it being possible to achieve a range of process pressures with the same gas flow rate. The plasma treatment time to obtain the desired hydrophilic coatings is typically about 0.1 minute to about 10 minutes, preferably about 1.5 to about 4 minutes, preferably about 1.5 to about 2.5 minutes.; and the RF power used to cause the reaction of the vapor is typically from about 1 to about 1,000 watts, preferably from about 50 to about 500 watts, most preferably from about 75 to about 250 watts. RF power typically employs ranges of approximately 100 to approximately 2500 watts and depends on the substrate being treated and the requirements for continuous placement. The resulting hydrophilic coatings can be produced in different thicknesses, but these are typically from about 0.01 to about 2.5 microns, preferably from about 0.5 to about 1 microns. While performing the remote plasma polymerization, the screen is preferably placed at a distance of about 1 to about 40 cm below the plasma zone. Similarly, the monomer inlet is preferably positioned at a distance of about 1 to about 35 cm below the plasma zone. The distance of the web downstream from (i.e., below) the plasma zone is more preferably from about 2 to about 2 cm, and most preferably from about 3 to about 10 cm. The distance of the monomer inlet downstream of the plasma zone and preferably from about 2 to about 20 cm, and most preferably from about 3 to about 10 cm. In a preferred embodiment, remote plasma polymerization of a non-saturable polymerizable compound according to the invention is preferably carried out under the following plasma conditions: Electrical power 10-100 watts Electrical voltage 8.102- 4-103 volts Gas flow of plasma 1-100 sccm (standard cubic centimeters) Monomer flow 1-50 mg / min Supply gas flow 1-100 sccm Monomer source temperature -80 ° C - + 80 ° C Frequency 1 kHz - 27.12 MHz , most preferably 13.6 or 27.12 MHz Plasma gases Ar, He, N2 Pressure 0.01-1 torr The polymeric coatings of the present invention which are capable of being obtained by the remote plasma-induced polymerization of an unsaturated polymerizable compounds on a web under the The aforementioned conditions with respect to the distance between the screen and the plasma zone, as well as the monomer input and plasma zone, are characterized The coatings obtained by the plasma-induced polymerization within the luminescence (or direct) by the fact that the repetitive units of the polymer chains are up to a greater limit identical in structure with those repetitive units obtained through a radical polymerization without plasma of the respective unsaturated compound. Typically from about 70% to about 98%, more typically from about 76% to about 98% and very typically from about 82% to about 98% of the repetitive structural units exhibit the same structure as the polymer obtained by the radical polymerization without plasma of the same monomer. Typically, from about 2% to about 30%, more typically from about 2% to about 24%, even more typically from about 2% to about 18% of the remaining structural units serve as covalently linking groups for the treated frames or as entanglement sites between the adjacent polymer chains. The qualitative and quantitative characterization of the plasma-induced polymer coating of the present invention can typically be determined as outlined below.

The uniform structure and relatively low controllable degree of entanglement of the coatings that are achieved in a surprising manner using the remote plasma polymerization of a saturated polymerizable compound under specific conditions of substrate placement and monomer input constitute a characteristic feature of the compositions. coatings, which are responsible for the durable wettability of the treated wefts. A specific advantage of the coatings is their strong adhesion to the surface of the treated weave obtained to a greater degree independently of the nature of the weft. As indicated, the plasma-induced hydrophilic coating exhibits a contact angle for water less than about 90 degrees, such that any water or water-based liquid placed on the screen will spread spontaneously on the coated surface of the screen . In a preferred embodiment, the treated screen can be further treated by exposure to a low temperature plasma gas composition (also referred to herein as a "surface modifier gas stream") or an energy source (also referred to herein as "radiation cure") such as an emitting device, infrared, electronic, thermionic or ultraviolet radiation. Apparatus that are suitable as energy sources in the present invention are disclosed in U.S. Patent No. 4,842,893 issued to Yializis on April 29, 1988, the disclosure of which is incorporated by reference herein. In the mode of the surface modifier gas stream the gas stream preferably comprises N2O and CO2, to increase the durability of the hydrophilic coating. In one of such preferred embodiment, the plasma gas composition will comprise from about 80 to about 40 mol% of N2O and d from about 20 to about 60 mol% of CO2, preferably d from about 70 to about 45 mol% of N2O and from about 30 mol. about 55 mol% of CO2, most preferably from about 60 to about 45 mol% of N2O and from about 40 to about 55 mol% of CO2, wherein the amount of N2O and CO2 in the mixture equals 100 to 10 mol%, for a sufficient time to modify the surface of the hydrophilic coating to increase its durability. In the radiation curing mode, the radiation source is preferably an electron beam gas discharge gun. The cannon directs a flow of electrons through a window emitting on the monomer, thereby curing the monomer further, which increases the durability of the hydrophilic coating. The cure is controlled by equalizing the electronic beam voltage to the dielectric thickness of the monomeric coating. For example, an electron voltage of 10 Kv will penetrate approximately 1 mire of the deposited monomer. The plasma process is generally practiced as follows. The starting screen to be treated is placed inside the vacuum chamber and the chamber pressure is reduced, typically to approximately 0.005 Torr. The process gas or gas mixture used is introduced into the chamber and the chamber pressure is stabilized at a pressure of 0.04-0.4 Torr. The interior dimension of the work area is approximately 1.73 x 0.76 x 1.02 meters (width x height x depth) for a total work volume of 1.34 cubic meters. A suitable form of high energy frequency, typically radio frequency energy of 13.56 MHz, is used to create the plasma; In the system described, this is achieved with a total energy input capacity of up to 2500 watts. The RF energy dissociates the gas, creating a plasma characterized by a distinctive luminescence. Since the process is conducted at reduced pressures, the global temperature of the gas is close to the ambient temperature, hence the reference to a cold gas plasma, a luminescent discharge, or a luminescent discharge of cold gas. The electrons or ions created in the plasm bombard the surface of the frame, extracting atoms or breaking bonds, creating free radicals. These free radicals are unstable and seek to satisfy a more stable state by reacting with free radicals or groups within the plasma gas, also establishing new portions on the surface of the web. In addition, the energetic electrons in the luminescent discharge fragment the molecules in the gas phase, leading to complex chemical reactions that result in the thin hydrophilic coating deposited on at least one surface of the weft. Typically, and preferably, before the deposition of hydrophilic coating plasma, an initial step is carried out. The purpose of this step is to clean the surface of the weft to promote the adhesion of the thin hydrophilic coating subsequently deposited. Cleaning can be achieved by subjecting the surface of the screen to radiation (referred to herein as "radiation cleaning") from a power source that includes but is not limited to infrared, electron beam, thermionic or ultra violet radiation or by plasma cleaning . Apparatus that are suitable as energy sources in the present invention are disclosed in U.S. Patent No. 4,842,893 issued to Yializis on April 29, 1988, the disclosure of which is incorporated by reference herein. In the radiation cleaning mode, the radiation source is preferably a gas discharge electron beam cannon. The cannon directs a flow of electrons through the emitting window on the surface of the frame, extracting in this way the atoms or breaking the bonds, thus creating free radicals. These free radicals are unstable and seek to satisfy a more stable state therefore they serve as binding sites for the monomers that are used to produce the hydrophilic coating of the weft. Cleaning is controlled by equalizing the voltage of the electronic beam to the desired thickness or dielectric depth. For example, an electronic voltage of 10 Kv will penetrate to a depth of approximately 1 miera.

In the plasma cleaning mode, the gases are usually either argon alone, oxygen alone, or mixtures of Ar and O2 (for example, ratio of 1: 1). The gas flow rates are typically in the range of about 20 to about 100 sccm (standard cubic centimeters / minute), and preferably from about 40 to about 80 sccm, and most preferably from about 50 to about 60 sccm. The RF energy is approximately 1100 watts, and the process pressure is approximately 0.040 Torr. After the optional initial step, the next step is the plasma deposition of the hydrophilic coating, as described above and in greater detail in the examples below. Useful materials such as polymeric films that are to be treated with plasma to provide a hydrophilic coating will be derived from thermoplastic polymers. In general, the term "thermoplastic polymer" is used herein to mean any thermoplastic polymer that can be used for the preparation of the films. Examples of the thermoplastic polymers include, by way of illustration only, interrupted end polyacetals, such as poly (oxymethylene) or polyformaldehyde, poly (trichloroacetaldehyde), poly (n-valeraldehyde), poly (acetaldehyde), poly (propionaldehyde) , and the like; acrylic polymers such as polyacrylamide, poly (acrylic acid), poly (methacrylic acid), poly (ethyl acrylate), poly (methyl methacrylate), and the like; fluorocarbon polymers, such as poly (tetrafluoroethylene), perfluorinated-propylene ethylene copolymers, ethylene-tetrafluoroethylene copolymers, poly (chlorotrifluoroethylene), ethylene-chlorotrifluoroethylene copolymers, vinylidene polyfluoride), vinyl polyfluoride), and the like; polyamides, such as poly (6-aminocaproic acid) or poly (e-caprolactam), poly (hexamethylene adipamide), poly (hexamethylene sebacamide), poly (11-aminoundecanoic acid), and the like; polyaramides, such as poly (imino-1,3-phenyleneiminophthaloyl) or poly (m-phenylene isophthalamide), and the like; polyarylenes, such as poly-p-xylylene, poly (chloro-p-xylylene), and the like; polyaryl ethers, such as poii (oxy-2,6-dimethyl-1,4-phenylene) or poly (p-phenylene oxide), and the like; polyaryl sulfones, such as poly (oxy-1,4-phenylenesulfonyl-1,4-phenyleneoxy-1,4-phenylene-1-isopropylidene-1,4-phenylene), poly (sulfonyl-1,4-phenyleneoxy-1,4-phenylene) -sulfonyl-4,4'-biphenylene), and the like; polycarbonates, such as poly (bisphenol A) or poly (carbonyldioxy-1,4-phenylene-isopropylidene-1,4-phenylene), and the like; polyesters, such as poly (ethylene terephthalate), poly (tetramethylene terephthalate), poly (cyclohexylene-1,4-dimethylene terephthalate) or poly (oxymethylene-1,4-cyclohexyl-enemethylene-terephthaloyl), and the like; polyaryl sulfides, such as poly (p-phenylene sulfide) or poly (thio-1,4-phenylene), and the like; polyimides, such as poIi (pyromelitimido-1,4-phenylene), and the like; polyolefins, such as polyethylene, polypropylene, poly (l-butene), poly (2-butene), poly (1-pentene), poly (2-pentene), poly (3-methi-1-pentene), poly (4-methyl-1-pentene), 1,2-poly-1,3-butadiene, 1,4-poly-1,3-butadiene, polyisoprene, polyioroprene, polyacrylonitrile, poly (vinyl acetate), poly (chloride) vinylidene), polystyrene, and the like; copolymers of the above, such as acrylonitrile-butadiene-styrene (ABS) copolymers, and the like. The preferred polymers are polyolefins and polyesters, with polyolefins being more preferred. Even more preferred are those polyolefins containing only hydrogen and carbon atoms and which are prepared by addition polymerization of one or more unsaturated monomers. Examples of these polyolefins include, among others, polyethylene, polypropylene, poly (l-butene), poly (2-butene), poly (l-pentene), poly (2-pentene), poly (3-methyl-1-) pentene), poly (4-methyl-1-pentene), 1,2-poly-1,3-butadiene, 1,4-poly-1,3-butadiene, polyisoprene, and the like. Furthermore, this term is implying to include mixtures of two or more poiiolefins and random and block copolymers prepared from two or more different unsaturated monomers. Because of their commercial importance, the most preferred polyolefins are polyethylene and polypropylene. In addition to polymeric films, the webs that can be used to produce the durable, wettable, liquid-permeable webs of the present invention include but are not limited to spin-linked, hydroentangled, sewn, and polymerically bonded non-woven webs. Suitable nonwoven webs are typically formed from organic textile fibers including but not limited to cotton, wood, wool, jute, viscose, rayon, nylon, polyester, polyolefins, carbon or mixtures thereof. Inorganic fibers such as glass and metal can be used alone or in combination or in combination with organic fibers. In the case of staple fibers, the length of the fiber varies from about 0.635 cm to 5.08 cm or greater. In the case of frames linked by rotation, the lengths of the fiber are undefined. The staple fibers used in the hydroentangled, sewn, and polymerically bonded nonwoven webs are processed through conventional textile machinery. For example, by producing a polymerically bonded nonwoven web, s can use a carding machine to form a continuous length instead of loosely associated two-dimensional fiber known as a carded web. These webs can be assembled to form a multiple layer or a three dimensional fibrous web of significant weight, for example, from about a few grams to thousands of grams per yard. In continuous non-woven fibrous webs, the textile fibers are arranged at various angles with respect to the longitudinal axis of the web. When a web is formed by the action of a carding machine, the fibers are usually oriented predominantly in the machine direction and, on the other hand, the isotropic webs can be formed such as by air placement. The fibrous webs described above are typically impregnated with a polymeric binder agent (polymerically bound). In the preferred form, the polymeric binders are applied as acrylic emulsions, polyvinyl acetate or similar polymeric nature, and mixtures thereof. Preferably, the fibers are non-woven and substantially oriented in a casual manner and adhesively bonded together with the polymeric binder. The hydroentangled and stitched webs are distinct from the polymerically bonded webs since they are mainly served in the physical entanglement of the fibers to provide the integrity of the web. In contrast to the polymerically linked and physically entangled webs, the spin-linked webs are typically composed of fibers of infinite length that are joined together through solvent by fusion. As indicated, the frames may be two-dimensional or may have a perforated three-dimensional structure made in accordance with the teachings of the incorporated references discussed in the Background Section, supra. The coatings are durable and increase the surface energy of the weft to make the treated weft more wettable. The coating is durable because it is maintained over time, even after exposure to water or other aqueous liquids. In this regard, the plots of the present invention are described in one respect in terms of their ability to remain wet during the time and / or after exposure to liquids. The ability to remain wet during the time is determined by measuring the post-aging contact angle of the weft. This measurement involves storing the treated weft at 74 ° C for 16 hours, to artificially age the sample, before measuring the contact angle. The ability to remain wet after exposure to liquids is determined by measuring the post-wash contact angle of the weft. This measurement involves placing a 5 x 5 cm sample of the treated weft in a 250 milliliter water bath at 65 ° C for 90 seconds with vigorous agitation before measuring the contact angle. Methods and devices for measuring the contact angle between a liquid and a surface of the screen are well known in the art. However, the treated frame that the applicants have discovered is treated by the surface contact angle of the water drop and the surface energy according to the procedures specified by the provisional method T565 pm-96 and the ACCU DYNE TEST, Diversified Enterprises (based on the ASTM D2578-84 technique). The values of the angle are reported as the average of the measurements in 5 samples. In one aspect, the treated fabric of the present invention will have a Post-aging contact angle that is not more than about 60 degrees greater than the Pre-aging contact angle of the treated fabric (i.e., the contact angle). as measured before storing at 74 ° C for 16 hours). Preferably, the treated web will have a Post-aging contact angle that is not more than about 40 degrees, more preferably not more than about 20 degrees, even more preferably no more than about 10 degrees, may than the contact angle of Pre-aging. In another respect, the treated web of the present invention will have a post-wash contact angle that is not more than about 60 degrees greater than the pre-wash contact angle of the treated web (i.e. the contact angle). as measured before the treated weft is placed in a 250 ml water bath at 65 ° C for 90 seconds with vigorous shaking). In this respect, the treated web will preferably have a post-wash contact angle that is not more than about 40 degrees, more preferably no more than about 20 degrees, even more preferably no more than about 10 degrees, greater than about 10 degrees. Pre-wash contact angle. In a preferred aspect, the treated web of the present invention will exhibit both Post-aging and Post-washing requirements discussed above.

Durable wettable liquid permeable webs of the present invention will exhibit either (preferably) both a post-aging or post-wash contact angle of less than about 90 degrees, preferably no more than about 70 degrees, more preferably no more than about 50 degrees, still more preferably no more than about 30 degrees, and most preferably no more than about 20 degrees.

II. Absorbent Articles As used herein, the term "absorbent article" generally refers to devices used to absorb and contend exudates from the body, and more specifically refers to devices that are placed against or near the user's body to absorb and contain the various exudates discharged from the body. The term "absorbent article" is intended to include diapers, catamenial pads, tampons, sanitary napkins, incontinence pads, training pants, and the like, as well as cleaning towels, bandages and wound dressings. The term "disposable" is used herein to describe absorbent articles that are not intended to be washed or restored or reused in another way as an absorbent article (ie, they are intended to be disposed of after limited use, and , preferably, to be recycled, composted or otherwise disposed of in an environmentally compatible manner). A "unitary" absorbent article refers to absorbent articles that are formed as a single structure or as separate parts joined together to form a coordinated entity such that separate manipulated parts such as a separate support and pads are not required. It is to be understood that the size, shape and / or overall configuration of the absorbent article, if any, in which the treated plies in accordance with the present invention are incorporated, or used in conjunction with, has no critical relationship or functional with the principles of the present invention. However, these parameters can be considered together with the attempted fluid and functionality attempted when the appropriate configurations of the frame are determined. In addition to the durable, wettable, permeable webs of the present invention, the absorbent articles will also comprise an absorbent core for the retention of any of the absorbed bodily fluids. Illustrative absorbent structures for use as the absorbent core in the present invention are described in U.S. Patent No. 4,950,264 issued to Osborn on August 21, 1990; U.S. Patent No. 4,610,678 issued to Weisman et al. on September 9, 1986; U.S. Patent No. 4,834,735 issued to Alemany et al. on May 30, 1989; European Patent Application No. 0 198 683, The Procter & Gamble Company, published on October 22, 1986 in the name of Duenk and others; U.S. Patent No. 4,673,402 issued to Weisman et al. on June 16, 1987, and U.S. Patent No. 4,888,231 issued to Angstadt on December 19, 1989. The absorbent core may further comprise the dual core containing a core of acquisition / distribution of chemically hardened fibers placed on an absorbent storage core as detailed in U.S. Patent No. 5,234,423 entitled "Absorbing article with characteristic elastic waist and increased absorbency" issued to Alemany and others, on August 10, 1993; and in U.S. Patent No. 5,147,345, entitled "High efficiency absorbent articles for the management of incontinence" issued to Young, LaVon and Taylor on September 15, 1992. The disclosure of all these patents is incorporated herein by reference.

A preferred embodiment of a unitary disposable absorbent article made in accordance with this is a catamenial pad, or a sanitary towel. As used herein, the term "sanitary napkin" refers to an absorbent article that is worn by women adjacent to the pudendal region, generally external to the urinary genital region, and which is intended to absorb and contain menstrual fluids and Other vaginal discharges from the body of the user (eg, blood, menstruation, and urine). Interlabial devices that reside partially within and partially outside the wearer's vestibule are also within the scope of this invention. Suitable feminine hygiene articles are disclosed in U.S. Patent No. 4,556,146 issued to Swanson et al. On December 3, 1985, U.S. Patent No. 4,589,876 issued to Van Tilberg on April 27, 1993, U.S. Patent No. 4,687,478 issued to Van Tilburg on August 18, 1987, U.S. Patent No. 4,950,264 issued to Osborn, Ill on August 21, 1990, U.S. Patent No. 5,009,653 issued to Osborn , III on April 23, 1991, United States Patent No. 5,267,992, issued to Van Tilburg on December 7, 1993, United States Patent No. 5,389,094 issued to Lavash et al. On February 14, 1995, patent No. 5,413,568 issued to Roach et al. on May 9, 1995, United States Patent No. 5,460,623 issued to Emenaker et al. on October 24, 1995, United States Patent No. 5,489,283 issued to Van. Tilburg on February 6, 19 96, U.S. Patent No. 5,569,231 issued to Emenaker et al. On October 29, 1996, and in U.S. Patent No. 5,620,430 issued to Bamber on April 15, 1997, the disclosure of each of the which is incorporated by reference here. In a preferred embodiment of the present invention, the sanitary napkin has two fins each of which are adjacent to and extend laterally from the lateral edge of the absorbent core. The fins are configured to cover the edges of the wearer's panties in the crotch region in such a way that the fins are disposed between the edges of the panties and the wearer's thighs. The fins serve at least two purposes. First, the fins help prevent the staining of the body and the wearer's panties by menstrual fluid, preferably forming a double-walled barrier along the edges of the panty. Second, the fins are preferably provided with fastening means on their garment surface in such a way that the fins can be folded back under the panty and fastened to the side that gives the pant garment. In this way, the flaps serve to keep the sanitary napkin properly placed in the pantyhose. The fins may be constructed of various materials including materials similar to the topsheet, the backsheet, tissue, or combinations of these materials. In addition, the flaps may be a separate element attached to the main body of the towel or may comprise extensions of the upper sheet and the back sheet (ie, unitary). A number of sanitary napkins having suitable or adaptable fins for use with the sanitary napkins of the present invention are disclosed in U.S. Patent No. 4,687,478 entitled "Towel-sanitary Towel", which was issued to Van Tilburg on August 18, 1987; and in U.S. Patent No. 4,589,876 entitled "Sanitary Towel", which was issued to Van Tilburg on May 20, 1986. The disclosure of each of these patents is hereby incorporated by reference. In a preferred embodiment of the present invention, an acquisition layer or layers may be placed between the topsheet and the absorbent core. The acquisition layer can serve several functions including improving the capillary action of the exudates on and towards the absorbent core. There are several reasons why and important improved capillary action of the exudates, including providing a more even distribution of the exudates throughout the absorbent core and allowing the sanitary napkin to be made relatively thin. The capillary action referred to herein may encompass the transportation of liquids in one, two or all directions (ie, in the x-y plane and / or z-direction). The acquisition layer may be composed of several different materials including non-woven or woven webs of synthetic fibers including polyester, polypropylene, or polyethylene; of natural fibers including cotton or cellulose; mixtures of these fibers; or any of the equivalent materials or combinations of materials. The examples of sanitary napkins having an acquisition layer and a topsheet are described more fully in U.S. Patent No. 4,950,264 issued to Osborn and in U.S. Patent Application Serial No. 07 / 810,774 , "Absorbent article with fused layers" presented on December 17, 1991 to names of Cree, and others. The disclosure of each of these references are hereby incorporated herein by reference. In a preferred embodiment, the acquisition layer may be joined to the top sheet by any of the conventional means for joining frames together, most preferably by fusion bonding as described more fully in the referred Cree application. The catamenial pads can be constructed as follows. On the release paper coated with silicone, a spiral pattern of H2031 Findlay thermal fusion adhesive is applied at 0.04 g / in2. This layer of adhesive is transferred on the upper side (which gives the user) of a secondary top sheet by laminating the secondary top sheet and the release paper coated together with a manual roller. The secondary topsheet is formed of a non-woven material known as Fort James Airlaid Tissue, Grade 817, commercially available from Fort James Corp. of Green Bay, Wisconsin. A top sheet of the present invention is applied to the adhesive side of the secondary top sheet and the two are joined together by gently pressing together with the manual roller. The quarter-inch double-sided tape strips are applied along both long edges of a polyethylene backsheet. The absorbent core is added to the structure to complete the absorbent structure. As used herein, the term "diaper" refers to a garment generally worn by infants and incontinent persons that is worn around the wearer's lower torso. However, it should be understood that the present invention is also applicable to other absorbent articles such as incontinence briefs, incontinence pads, training pants, diaper inserts, facial tissues, paper towels, and the like. In general, a diaper of the present invention will comprise a topsheet permeable to the liquid of the present invention; a back sheet impervious to the liquid joined with the upper sheet; and an absorbent core placed between the top sheet and the back sheet. Additional structures features such as elastic members and fastening means for securing the diaper in place on a wearer (such as tape tab fasteners) may also be included. Although the top sheet, the backsheet, and the absorbent core can be assembled in a variety of well-known configurations, a preferred diaper configuration is generally described in U.S. Patent No. 3,860,003 (Buell), issued January 14, 1975, disclosure of which is incorporated by reference. Alternatively, the preferred configurations for disposable diapers herein are also disclosed in U.S. Patent No. 4,808,178 (Aziz et al.) Issued February 28, 1989.; U.S. Patent No. 4,695,278 (Lawson) issued September 22, 1987; and in U.S. Patent No. 4,816,025 (Foreman) issued March 28, 1989, the disclosures of each of these patents are hereby incorporated by reference. Incontinence articles suitable for adult users are disclosed in U.S. Patent No. 4,253,461 issued to Strickland et al. On March 3, 1981; U.S. Patent Nos. 4,597,760 and 4,597,761 issued to Buell; U.S. Patent No. 4,704,115; U.S. Patent No. 4,909,802 issued to Ahr et al., U.S. Patent No. 4,964,860 issued to Gipson et al. on October 23, 1990; and in U.S. Patent Application Serial No. 07 / 637,090 filed by Noel et al. on January 3, 1991 (PCT Publication No. WO 92/11830 published July 23, 1992). The disclosure of each of these references is incorporated herein. The absorbent core of the diaper is placed between the top sheet and the back sheet. The absorbent core can be manufactured in a wide variety of sizes and shapes (e.g., rectangular, hourglass, asymmetric, etc.). However, the total absorbent capacity of the absorbent core must be compatible with the design fluid load for the intended use of the absorbent article or diaper. In addition, the size and absorbent capacity of the absorbent core can vary to encompass users ranging from babies to adults. As indicated, the absorbent core can include a liquid distribution member. In a preferred configuration, the absorbent core preferably further includes a acquisition layer or member in liquid communication with the liquid distribution member and located between the liquid distribution member and the top sheet. The acquisition layer or member may be made of several different materials including woven or non-woven synthetic fiber webs including polyester, polypropylene or polyethylene, natural fibers including cotton or cellulose, mixtures of these fibers, or any equivalent materials or combinations of materials. In a preferred embodiment, the diaper will comprise elasticized folds for the leg. Elastic leg cuffs can be constructed in a number of different configurations, including those described in U.S. Patent No. 3,860,003; U.S. Patent No. 4,909,803, issued to Aziz et al. on March 20, 1990; U.S. Patent No. 4,695,278 issued to Lawson on September 22, 1987; and in U.S. Patent No. 4,795,454 issued to Dragoo on January 3, 1989, each of which is incorporated herein by reference. In use, the diaper is applied to a wearer by placing the posterior waistband region under the user's back, and pulling the rest of the diaper between the user's legs such that the waistband front region is placed across the front of the diaper. user. The tape tab or other fasteners are then preferably secured in the areas facing the diaper. lll. Examples The following examples are illustrative and are not intended as a limitation of the invention disclosed and claimed herein.

Example 1 A test screen of polyethylene film material (30 cm x 20 cm) is placed on the bottom (20 cm below the bottom electrode) of a vacuum chamber of the plasma discharge unit (APS Inc. Model D) . The plasma chamber is evacuated. When the internal pressure of the chamber reaches 20 mTorr, a carrier gas (Ar) is continuously introduced into the chamber at a constant rate (10 sccm), in such a way that the pressure inside the chamber is maintained at 63 mTorr by the equilibrium of the continuous evacuation and the introduction of the carrier gas. While maintaining the conditions described above, the low temperature plasma is generated inside the chamber for a period of 1 minute, supplying a high frequency electric power of 100 W at a frequency of 40 kHz to expose the surface of the film to the low temperature plasma. Then, a monomer (acrylic acid) is introduced into the chamber at a constant rate to maintain the constant pressure inside the chamber (165 mTorr). While the conditions described above are maintained, the low temperature plasma (100 W, 40 kHz) is generated inside the chamber for a period of 10 minutes. After the treatment, the chamber is evacuated (30 mTorr) and flooded with atmospheric air. The treated weft is tested by the contact angle of the water drop on the surface and surface energy according to the procedures specified by the provisional method T565 pm-96 and ACCU DYNE TEST, Diversified Enterprises (based on the ASTM D2578 technique). -84), to give the results shown in Table 1.

Table 1 a: samples where they were kept in an oven at 74 ° C for 16 hours before the contact angle measurement.

Comparative examples 2 to 4 This example represents the contact angle data (as shown in Table 2, which are to be compared with Table 1) for a polyethylene film exposed to a carrier gas (Ar) and a monomer ( acrylic acid) without plasma discharge (Example 2), a film exposed to a carrier gas (Ar) and a plasma discharge (100 W) for 11 minutes (Example 3), and a film placed between the electrodes (direct plasma) exposed to a carrier gas (Ar), a monomer (acrylic acid), and a plasma discharge (100 W, 11 min) (Example 4). From the comparison with Table 1, it is seen that the remote plasma provides a web that better retains its hydrophilic capacity after accelerated aging, relative to a web prepared under various other conditions, including direct plasma polymerization.

Table 2 the value of the contact angle is an average of 5 measurements.

Claims (14)

1. A remote plasma process for making a permanently wettable, liquid-permeable web to be used as a topsheet in an absorbent article comprising the process: (i) introducing a web into a plasma reaction chamber comprising a reaction zone of plasma, where the web is placed outside the plasma reaction zone; and (ii) coating at least one of the screen surfaces with the monomers polymerized by plasma polymerization, wherein the coating is less than 2.5 microns thick and is derived from a monomer gas stream that will provide a coating hydrophilic upon the occurrence of plasma polymerization and wherein the monomer gas stream is introduced outside the plasma reaction zone; said process characterized in that the web is selected from the group consisting of polymeric films, apertured polymeric films, non-woven webs and non-woven webs with apertures; wherein the polymerized monomers cause at least one surface of the screen to become permanently wettable.

2. The process according to claim 1, wherein at least one wet-permeable, liquid-permeable web surface has a Post-aging contact angle that is not more than 60 degrees greater than the contact angle of the liquid. Pre-aging and most preferably no more than 20 degrees greater than the Pre-aging angle, preferably no more than 40 degrees May than the Pre-aging contact contact angle.

3. The process according to any preceding claim, wherein at least one wet-permeable, liquid-permeable weft surface has a post-wash contact angle that is not more than 60 degrees greater than the Pre-contact angle. washing, preferably is not more than 40 degrees greater than the Pre-wash contact angle and most preferably not more than 20 degrees greater than the Pre-wash contact angle.

4. The process according to any preceding claim wherein the process further comprises the step of cleaning the surface of the frame by exposing the surface to the plasma conditions or to an energy source selected from the group consisting of infrared radiation, electron beam , thermionic or ultraviolet radiation and mixtures thereof, before introducing the gaseous stream of the monomer from step (ii).

The process according to claim 4 wherein the step of cleaning the surface of the weft by exposing the weft to the plasma conditions comprises introducing the gas stream comprising a material selected from the group consisting of Ar , O2, and mixtures thereof.

6. The process according to any preceding claim, wherein the process comprises the step of further modifying the hydrophilic surface by introducing the web formed in step (ii) into a gaseous surface modifier stream, the gaseous stream comprising N2O and CO2; or a source of energy or a source of energy selected from the group consisting of infrared radiation, electron beam, thermionic or ultraviolet radiation and mixtures thereof.

The process according to any preceding claim, further comprising the final step comprising piercing the coated web.

The process according to any preceding claim, wherein the polymeric film is derived from a material selected from the group consisting of polyolefins, polyesters, and mixtures thereof.

9. The process according to claim 8, wherein polymeric film is derived from a material selected from the group consisting of polyethylene, polypropylene, poly (l-butene), poly (2-butene), poly (l-pentene) , poly (pentene), poly (3-methyl-1-pentene), poly (4-methyl-1-pentene), 1,2-poly-1,3-butadiene, 1,4-p 1,3-butadiene, polyisoprene, mixtures thereof, random copolymers thereof, and block copolymers thereof.

10. The process according to any preceding claim, wherein the monomer gas stream comprises a monomer containing at least one vinyl group.

The process according to claim 10, wherein the monomer gas stream comprises a monomer selected from the group q consisting of: a) acrylic and methacrylic acid of the general formula H2C = C (R) C (O) OH, b) acrylates and methacrylates of the general formula H2C = C (R2) -C (O) OR3, c) acrylamides and methacrylamides of the general formula (R2) (R2) C = C (R2) - C (O) NHR3, d) maleic and fumaric acid of the general formula HO (O) C (R2) = C (R2) -C (O) OH, e) maleates and fumarates of the general formula R3O (O) C (R2) = C (R2) C (O) OR3, 0 vinyl ethers of the general formula (R;)) (R;)) C = C (R;)) -OR 'g) N-vinyl-2- pyrrolidone of the formula h) vinyl acetate of the general formula (R) (R) C = C (R OC (O) CH3, i) aliphatic vinyl compounds of the general formula R 2 CH = CHR 3, and mixtures thereof, wherein each R 2 is independently hydrogen or C 1 -C 0 alkyl, and each R 3 is independently an aiiphatic hydrocarbon group of up to about 10 carbon atoms which is substituted by one or more groups such as carboxy, hydroxy, amino, or a (poly) ethylene oxide group optionally substituted by one or more sulfates, phosphates, or groups or mixtures of these groups.

12. The process according to claim 11, wherein the monomer gas stream comprises a monomer selected from the group consisting of acrylic acid, methacrylic acid, hydroxyethyl methacrylate, methyl methacrylate, dimethylaminoethyl methacrylate, 2-hydroethylacrylate, N, N-dimethylacrylamide. , N-acryloylmorpholine, ethylene glycol dimethacrylate, mixtures thereof.

13. The process according to any preceding claim, wherein the gas of the monomer gas stream is ionized by pulsation d microwave or radio waves of high frequency.

14. An absorbent article characterized in that the absorbent article comprises a liquid permeable, durably wettable top sheet produced by the processes of any of the preceding claims.