MXPA99002370A - Apertured films having durable wettability and processes for making them - Google Patents

Abstract

This invention relates to a process for forming a single-layer, durably wettable polymeric web having a plurality of apertures. This process comprises melting a mixture of at least one thermoplastic polymer and at least one migratable surfactant and extruding the mixture to form a single-layer, substantially continuous polymeric film. The film is then apertured using high pressure fluid flows. Aperture formation is conducted when the single-layer polymeric film has a contact angle of at least about 30°, to minimize wash-off of the surfactant impregnated in the polymer web. The invention also relates to durably-wettable apertured webs.

Description

FILMS WITH OPENINGS THAT HAVE DURABLE HUMANTABILITY AND PROCESSES TO PREPARE THEM TECHNICAL FIELD The present invention relates to a process for making apertured, durably wettable polymeric films, which are particularly suitable as top sheets for absorbent articles. In particular, the invention relates to a process for piercing a substantially continuous polymer film to coincide with the pattern of one or more three-dimensional forming structures. This process results in a three-dimensional polymeric screen with openings. As described in detail below, the continuous polymeric film is prepared by extruding a mixture of polymeric resin and a wetting agent (eg, a surfactant), which is incompatible with the polymeric material. After perforating this film, the incompatible wetting agent migrates or "blooms" to the surface to provide a three-dimensional apertured polymeric web, lastingly wettable. The present invention further relates to a permanently wettable plastic aperture screen exhibiting transmission capabilities, exhibiting highly desirable vapor transmission capabilities and durable fluid, in addition to the visual and tactile impressions that are desired by consumers. . In another aspect the present invention relates to a multi-phase process for making these plastic frames with openings.

BACKGROUND OF THE INVENTION Three-dimensional, macroscopically expanded polymeric openings are generally known in the art. As used herein, the term "macroscopically expanded expanded," when used to describe three-dimensional plastic frames, battens, and films, refers to the wefts, tapes, and films that have been made conformed to the surface of the three-dimensional structure of formation, in such a way that both of its surfaces exhibit the three-dimensional pattern of the formation structure, the pattern being easily visible to the naked eye when the perpendicular distance between the observer's sheet and the plane of the frame is approximately 12 inches. By way of contrast, the term "flat," when used in the present to describe plastic wefts, tapes, and films, refers to the general condition of the weft, tape, or film when viewed with the naked eye on a scale microscopic In this context "flat" webs, tapes and films can include wefts, tapes and films that have fine-scale surface aberrations on one or both sides, the surface aberrations not being easily visible to the naked eye, when the distance perpendicular between the observer's blade and the plane of the frame is approximately 12 inches or more. A macroscopically expanded three-dimensional apertured polymeric web that is particularly well suited for transferring fluids deposited onto a surface thereof to its opposite surface and subsequently isolating the fluid transferred from the wearer's skin is disclosed in the commonly assigned US patent. United States No. 3,929,135, issued to Thompson on December 30, 1975, the disclosure of which is incorporated herein by reference. Thompson describes a three-dimensional, macroscopically expanded plot (eg, a top sheet), composed of a material impervious to liquid, but provided with a pattern of tapered capillaries, the capillaries having a base opening in the plane of the top sheet and a vertex opening remote from the plane of the top sheet, the apex opening being in intimate contact with the absorbent pad used within the disposable absorbent web. The Thompson upper blade allows free transfer of fluids from the user's body to the absorbent element of the device, while inhibiting the reverse flow of these fluids. This provides a relatively much more dry surface in contact with the user that had previously been obtainable. Another three-dimensional, macroscopically expanded plastic screen with openings, well suited for use as a topsheet in absorbent strips such as sanitary napkins, is disclosed in commonly assigned U.S. Patent No. 4,342,314 issued to Radel and Thompson on August 3, 1982, the patent being incorporated herein by reference herein. The three-dimensional, macroscopically expanded plastic web disclosed in the Radel and Thompson patent exhibits an appearance and tactile impression in the form of fiber, which has been favorably received by consumers when used as a contact surface for the user. According to the teachings of the aforementioned patents commonly assigned to Thompson and Radel, plastic wefts of the above-mentioned type can be made by applying a fluid pressure differential to the weft while it is held on a three-dimensional structure until the web is macroscopically expanded to meet the three dimensional cross-section of the forming structure on which it is supported. When the perforation of the macroscopically expanded three-dimensional weft is desired, the fluid pressure differential is applied continuously until such time as the perforation of the weft in the areas coinciding with the openings of the forming structure has been completed. Although the training processes (including the fluid-based systems discussed above and the vacuum-based systems discussed below), single-phase (ie, a drilling phase), have been successfully used in the production of plastic wefts with Macroscopically expanded three-dimensional openings, which exhibit many features, generally seen as favorable by consumers, such single-phase processing techniques are unable to give certain desired characteristics in a single finished frame structure, particularly at high production speeds. In this regard, a multi-phase fluid-based process, such as that described in U.S. Patent No. 4,609,518, issued September 2, 1986 to Curro et al., Hereinafter referred to as "518 patent") , was 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 of microscopic size), in the opposite direction to those formed for large openings, hides the ability of the initially unabsorbed fluid to leave the surface of the screen. Therefore, the fluid not immediately transported through the large openings is limited from coming out of the surface of the weft, and is subsequently captured through the large openings and is deposited within the core of the article, where it is locate the plot of a top sheet material. These small openings formed outward also reduce the level of the skin / weft contact, and reduce the stiffness of the film, and thus a more comfortable feeling for the user. The 518 patent discloses films where very small openings are formed in the same direction as the macro openings. An alternative for the formation of films with three-dimensional openings, through the use of fluid pressure differentials, is the use of vacuum forming of such structures. For example, U.S. Patent No. 3,054,148 issued September 18, 1951 to Zimmerli discloses a perforated film material, formed by heating a film on a perforated screen, while sufficient vacuum is applied to the underside of the film. sieve to form the openings in the film. The use of vacuum formation is limited in that the formation of openings in two directions, as described in the '518 patent, it is not possible because the heating of the apertured film for the requirement of the second step damages the openings formed in the first step. As such, the tact / feel benefits obtained using that process are not able to be obtained using vacuum punching methods. In addition, micro size openings obtainable using fluid formation (e.g., U.S. Patent No. 518) are not generally obtainable using vacuum forming processes, because the typical vacuum source applied in these processes is insufficient to break the film to form micro-size openings. Regardless of the means employed for the formation of the opening, where a wettable material is desired, the above references generally obtain such a structure by the surface treatment of the naturally hydrophobic polymeric web with a wetting agent. The surface treatment is generally achieved by either spraying the surfactant onto the surface of the weft or by immersing the weft in a bath containing surfactant. Regardless of which of these methods is employed, surface treatment suffers from the inability to precisely control the location and level of treatment, as well as adverse effects caused by migration of significant amounts of surfactant to openings or other components (e.g. , the absorbent core) when the film is used with openings with a top sheet in an absorbent article. The surface treatment suffers in addition to the disadvantages that wetting agents or desirable surfactants tend to be removed or removed upon repeated exposure to fluids. Therefore, when used as a top sheet in an absorbent article, the treated films lose their ability to transport fluids away from the skin and into the core of the article after repeated wetting. U.S. Patent No. 4,535,020, issued to Thomas et al., August 13, 1985, addresses some of the problems associated with vacuum-formed, surface-treated aperture films by incorporating hydrophilic surfactant into the polymer resin before the extrusion for the formation of the film.

After the extrusion of the resin / surfactant mixture, and the subsequent conversion formation of the openings, the incompatible surfactant eventually blooms to the surface of the film to provide a more durably wettable web. As noted above, however, the use of vacuum forming means to perforate the films has inherent limitations in relation to the use of the fluid forming means. In this regard, United States Patent No. 5,520,875 granted issued May 28, 1996 to AJ Wnuk et al. Addresses the problem of entrained surfactant, wherein the openings are formed using a fluid pressure differential to co-extrude. the multiple layers of the polymeric film, referred to herein as the core layers and the outer layers. The outer layer, which is exposed to the aperture-forming fluid, is free of surfactant, while the core layer contains a migratable surfactant. After co-extrusion and aperture formation, the surfactant migrates from the core layer to the surface of the outer layer, to provide a durable multi-layer wettable weft. As such, the patent addresses many of the undesirable aspects of previous drilling processes. However, this process is clearly limited to the production of multi-layer films. Therefore, the patent described a process that requires additional raw material that could not serve any other function than to prevent the surfactant from being entrained during manufacture, thus potentially adding the caliber, complexity and / or undesirable costs when it uses the laminate as a top sheet of the absorbent article. Similarly, the patent requires the coextrusion of the separate layers of material, which can be added to the complexity of the training process and to the training equipment. Despite the teachings of the prior art, here remains a need for a single-ply, apertured film material that offers both durable wettability and a smooth feel to the skin. Also here remains the need for a process that provides a film with openings, of a single layer, having improved durable wettability, wherein the process minimizes the entrainment of the surfactant during the formation of the opening using a fluid pressure differential. . Here also remains the need for a multi-stage process to produce a film with single layer openings, which has improved durable wettability and smooth skin feel. Accordingly, it is an object of the present invention to provide a process wherein various combinations of the previously compatible characteristics can be provided in a single-layer apertured polymeric fabric. It is another object of the present invention to provide a multi-stage process for producing the permanently wettable, apertured plastic webs, wherein the different phases of the process can be separated from one another, either temporarily or spaced apart or both. It is yet another object of the present invention to provide plastic screens with openings that offer improved durable wettability together with highly preferred appearance, softness and touch printing. It is still another object of the present invention to provide a process for fluid drilling a continuous polymeric film, wherein the process reduces the carryover of the surfactant. Reducing the carryover of the surfactant provides two distinct benefits. First, it reduces the surfactant levels that are required to obtain a wettable web. Second, it reduces the level of the surfactant entrained during the processing of the film, prevents unwanted foaming and alleviates the adverse effect of surfactants on the operation of the machine after continuous exposure.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a continuous process for forming a durable, wettable, single-layer polymeric web having a plurality of openings. This process comprises the steps of: (a) melting a mixture of at least one thermoplastic polymer and at least one migratable surfactant and extruding the mixture to form a substantially continuous, single-layer polymeric film; (b) continuously holding the film on a forming structure that exhibits a three-dimensional pattern defined by a multiplicity of openings that is placed on the opposite surface of the forming structure in fluid communication with each other, moving the forming structure in a direction parallel to the direction of motion of the film frame and carrying the film in the direction; and (c) applying a fluid pressure differential across the thickness of the film to I or along the direction of movement of the forming structure exhibiting the openings, the fluid pressure differential being large enough to be such that the film breaks in those areas that match the openings in the formation structure; wherein the formation of the opening in step (c) is performed when the surface of the film formed in step (a) has a contact angle for water of at least about 30 °. When this single-phase process is employed, the openings in the forming structure can be either microscopic, macroscopic or both macroscopic and microscopic in size. Prepared films that use this process have the openings formed in only one direction. The invention also pertains to a multi-phase process to form a durable, wettable, single-layer polymeric web having openings formed in both directions. The process comprises the steps of: (a) melting a mixture of at least one thermoplastic polymer and at least one migratable surfactant, and extruding the mixture to form a substantially continuous polymeric film; (b) continuously holding the film on a first forming structure that exhibits a multiplicity of openings (preferably the openings are of microscopic size), which is placed on opposite surfaces of the forming structure in fluid communication with one another , the training structure moving in a direction parallel to the travel direction of the film and carrying the film in the direction; (c) applying a first fluid pressure differential through the thickness of the film along the direction of movement of the forming structure exhibiting the openings, the fluid pressure differential being large enough to make the film break in those areas that match the openings in the 5-formation structure; (d) continuously holding the screen with openings on a second forming structure exhibiting a multiplicity of openings (preferably, the openings are of macroscopic size when the openings in the first forming structure are of microscopic size), which places the opposing surfaces of the second forming structure in fluid communication with each other, moving the second forming structure in a direction parallel to the direction of travel of the weft with openings and leading to the frame with openings in the direction; and (e) applying a second fluid pressure differential through the thickness of the weft with openings along the direction of movement of the forming structure, wherein the second fluid pressure differential is large enough to break the plot with openings in those areas that match the openings of the second forming structure while substantially maintaining the integrity of the openings formed by the first fluid pressure differential; wherein the formation of the openings in step (c) is carried out when the film formed in step (a) has a contact angle for the water of at least about 30 degrees, and wherein the formation of the openings in the step (e) is performed when the surface of the apertured screen formed in step (c) to be subjected to the second differential of fluid pressure in the Second formation structure, have a contact angle for water of at least about 30 degrees. As indicated above, it is preferred that one of the formation structures in the multi-phase process will have openings of microscopic size, and the other forming structure will have macroscopic size opening. Most preferably, the first forming structure will have openings of microscopic size and the second forming structure will have macroscopic sized openings. In addition, unlike single-phase processes, the multi-phase process allows the formation of the openings in two different directions. That is, after a continuous web is perforated on the first forming structure, the web with openings can be introduced into the second forming structure such that the openings are formed in a direction opposite to those formed in the first structure. deformation. This is achieved by simply introducing the apertured web in such a way that the surface contacting the second forming structure is not the surface in contact with the first forming structure. It is apparent that the multi-phase process of the present invention can be carried out to obtain plots having micro size holes in both directions or macro size hole in both directions. The invention also pertains to a single-layer fluid handling polymeric web comprising a thermoplastic material and a migrating surfactant, the web having first and second surfaces, the web also comprising a multiplicity of microscopic openings created in the web. first surface of the weft, the microscopic openings exhibiting a sufficient capillary suction degree to transmit the static fluid contained on the surface of the objects that are in contact with the surface of the weft, generally in the direction of the second surface of the weft by capillary attraction. In a preferred embodiment, the single-ply web containing the thermoplastic material and the migratable surfactant comprises: a. a multiplicity of openings of macroscopic cross-section to transmit the fluids that are deposited dynamically on the first surface of the weft towards the second surface of the weft, using the dynamics and gravitational height of the fluid with a primary raid force, each of the macroscopic openings coming from the first surface of the weft and having a continuously interconnected side wall having the determination to form at least one opening in the second surface of the weft, thereby transmitting the volume of fluid dynamically deposited from the first surface towards the second surface of the weft, through the macroscopic openings; and b. a multiplicity of microscopic openings coming from either the first or the second surface of the screen, the microscopic openings exhibiting a degree of capillary suction sufficient to transmit the static fluid contained on the first surface of the objects that are in contact with the first surface of the weft, generally in the direction of the second surface of the weft by means of capillary attraction. Although the present invention can take many different forms of execution, the formation processes of the screen of the invention comprise at least one phase of formation of the openings, which uses a differential of fluid pressure to achieve its objective. Where a durable wettable weave is desired that has only micro sized or macro size openings, only one phase of openings formation is required. In contrast, where a durable wettable pattern having as many macro-size orifices of micro size is desired, two discrete forming phases are used, each of which uses a fluid pressure differential. One of the phases involves the microscopic perforation of the weft in those areas that coincide with the microscopic openings in the formation structure, using sufficient fluid pressure differentials. The other phase involves the macroscopic perforation of the weft in those areas that coincide with the macroscopic openings in another formation structure using sufficient fluid pressure differentials. Applicants have discovered that, without taking into account that if desired, a single-layer polymeric web having only macro-size or micro-size or a single-layer polymeric web having both of the macro-size orifices and micro, obtaining durable wettability using a migratable, impregnated surfactant, requires that the formation of the openings be completed within specific time periods. In particular, as described in detail below, it is important that the formation of the openings (macro and / or micro) be completed before a significant portion of the surfactant has "surfaced" towards the surface of the polymeric web. The formation of the opening before significant upwelling reduces the carryover of the surfactant that would otherwise result from the high pressure fluid differentials applied to the flat film. This provides the benefits in which less surfactant is required in the resin mixture to obtain the desired wettability of the resulting film. In addition, the reduction of the carryover of the surfactant during the processing, reduces the undesirable foaming (and the corresponding use of antifoaming agents), reduces the adverse objects caused by the prolonged exposure of the equipment to high levels of surfactants contained in aqueous systems , reduces the environmental problems of undesirable discharges, and reduces the undesirable redeposition of surfactants on the screen with openings. The order in which the phases of the formation of openings are applied will depend on the particular characteristics desired in the three-dimensional, resultant polymeric apertured screen. Where at least two training phases are necessary, these can be carried out on a simple training structure including all the desired characteristics in the resulting plot or on multiple training structures, each of which imparts only a part of the desired characteristics to the plot. The fluid medium applied during each of the formation phases can be similar or different from each other, depending again on the particular characteristics desired in the resulting polymeric web.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a top plan view of a sanitary towel with parts of the sanitary towel cut to show more clearly the construction of the sanitary napkin. Figure 2 is a cross-sectional view of the sanitary napkin of Figure 1, taken along section lines 2-2. Figure 3 is an enlarged, perspective illustration of a representative absorbent article in the form of a sanitary napkin or catamenial pad in accordance with the present invention. Figure 4 is a perspective illustration, partially segmented, enlarged of a representative absorbent article in the form of a diaper made in accordance with the following invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION Although the present invention will be described in the context of providing plots with single layer, durably wettable openings, particularly suitable for use as a user interface in absorbent articles, such as sanitary napkins, disposable diapers, wound dressings and similar, the present invention is in no way limited to these applications. On the contrary, the present invention can be practiced whenever it is desired to produce films or plastic wefts exhibiting characteristic properties, aesthetics, etc., not previously obtainable using the prior art weft forming processes. The patterns of openings created can be of any desired shape, these can be regulated or random, cross-linked or non-cross linked, continuous or interrupted or any desired combination thereof. Furthermore, although the formed webs or processes of the present invention are single layer films, these can be combined after forming with other materials to form a laminated structure. Similarly, single layer films can be further processed to modify the surface characteristics of one or both surfaces of the apertured film. For example, in one embodiment, a film of the present invention can be surface treated with a hydrophobic material in accordance with the teachings of the co-pending United States Patent Application Serial No. 08 / 442,935, filed May 31, 1995 by Oulette et al. To provide a material that exhibits a surface energy gradient. In a preferred embodiment to obtain a material with such a gradient, the apertured film of the present invention is a weft having macro size apertures formed in one direction and micro size apertures taken in the put direction. It is further preferred that the weft be subjected to the corona discharge treatment (discussed below) at some time before the treatment of the weft with a hydrophobic material, to increase the binding of the hydrophobic material to the weft. The detailed description of the structures disclosed herein and their suggested uses as top sheets and backsheets in the context of the disposable absorbent articles will enable a person skilled in the art to easily adapt the invention to produce well-suited frames for other applications. .

I. Definitions With respect to the apertured screens of the present invention, an "amplitude" of the given aperture refers to a distance from the surface where the aperture originates to the surface where the aperture ends. As used herein, the term "female side" means the surface side of a weft where the openings described originate. In contrast, the term "male side" means the side or surface of a frame where the openings described finish. As such, during a given phase of the formation of the opening, the surface of the screen that is contacted by the fluid pressure will be the female side with respect to that phase of the formation of the opening, while the side in contact with the formation structure (and not exposed to the fluid pressure), is the male side, with respect to that phase of the formation of the opening. Of course, for the frames that have openings formed in opposite directions, both surfaces will have female openings and male openings. As used herein, the terms "microscopic" and "micro-size" are used interchangeably and refer to the apertures in the weft (and openings in a forming structure to form these weft openings), which are not Individually identifiable as seen with the naked eye, when the perpendicular distance between the eye of the observer and the plane of the frame is approximately 12 inches. In contrast, the terms "macroscopic" and "macro-size" are used interchangeably and refer to the weft openings (and openings in the forming structure to form these openings), which are individually identified as observed simple view when the perpendicular distance between the eye of the observer and the plane of the frame is approximately 12 inches. Typically, the use of the term "microscopic" refers to an aperture having as its largest dimension as measured perpendicular to its amplitude and on the female side of the weft, a dimension not greater than about 300 μm, preferably not greater than 250. μm, more preferably not greater than about 200 μm, still more preferably not more than about 150 μm, while "macroscopic" refers to an opening having a dimension greater than about 300 μm, as measured perpendicular to its amplitude and over the female side of the weft As used herein, the term "migratable surfactant" refers to any surfactant that is chemically incompatible with the thermoplastic polymer with which it is combined, such that it will migrate to the film surface for a while to alter the dynamics of fluid handling of the polymer surface. Useful examples such as the surfactant and the thermoplastic polymer are described below.

II. Polymeric webs of suitable formation for perforation Preferred polymeric materials useful herein include polyolefins, particularly polyethylene, polypropylene and copolymers having at least one olefinic constituent. Also, other thermoplastic materials, such as polyesters, nylon, copolymers thereof, and combinations of any of the foregoing may be suitable as the polymeric material. The surfactant materials useful herein are necessarily incompatible with the polymeric material, such that they will migrate towards the surface of the film after the formation of the aperture. (Polymeric webs that have soluble surfactants provide mainly durable wettability, because when the surfactant molecules are entrained during exposure to the fluids in use, they are replaced by additional molecules contained within the polymeric web. when conducting the formation of the opening in relation to the outcrop of the surfactant towards the surface of the film, it is discussed in detail below). In addition, the surfactant must be such that it makes the resulting film relatively hydrophilic. In general, the surfactant molecules are composed of functional groups that have opposite solubility tendencies. Typically one group is a water-insoluble / oil-soluble / non-polar hydrophobic chain (e.g., hydrocarbon, silicone) of the opposite group is a hydrophilic / water-soluble / polar group. The surfactants are classified according to the electrical charge of the polar hydrophilic portion. In anionic surfactants, the polar group carries a negative charge. The cationic surfactants carry a positive charge. In amphoteric surfactants, both positive and negative charges are present in the same molecule. In nonionic surfactants, there is no electrical charge in the molecule. For example, the polar hydrophilic group and the nonionic surfactants can be a chain of water-soluble ethylene dioxide units or a group carrying multiple hydroxyl functionalities, for example, glycerol or sorbitol derived groups. The chemistry of surfactants is very broad and is described more fully in the Kirk-Othmer encyclopedia and the chemical technology of Chemical Technology, 3rd. Edition, Volume 22, page 332-432, incorporated herein by reference. In the process of the present invention, the surfactants of each class mentioned above can be used. However, where the resultant three-dimensional plastic web is to be used in absorbent articles such as sanitary napkins, pantiliners, disposable diapers, incontinence articles and the like, where contact with human skin tissue is expected, the skin irritation potential of the surfactant should be considered. In general, cationic surfactants tend to be more irritating than anionic agents, which tend to be more irritating than any of the nonionic amphoteric types. Therefore, the particularly preferred surfactants are those from non-ionic families, including, for example: sorbitan esters, ethoxylated sorbitan esters, silicone copolymers, chemical fluoro-based surfactants, alcohol ethoxylate, alkyl phenol ethoxylate , carboxylic acid esters, glycerol esters, polyoxyethylene fatty acid esters, esters of aliphatic polyoexethylene carboxylic acids, related to abietic acid, anhydrosorbitol esters, ethoxylated anhydrosorbitol esters, ethoxylated natural fats, oils and waxes, esters of glycol fatty acids, carboxylic amides, diethanolamine condensates, monoalkanol amine condensates, polyoxyethylene fatty acid amides, polyalkylene oxide block copolymers. Preferred nonionic surfactants include sorbitan esters, silicone copolymers and chemical-based surfactants. Particularly preferred surfactants useful herein include Atmer 100® (based on ICI sorbitan), Atmer 645® (ICI), Q4-3667 (Dow Corning silicone copolymer), and FC21802 (fluorochemical); 3M Company). The skilled artisan will recognize that any surfactant that is incompatible with the polymer component and that is capable of modifying the surface characteristics of the polymer can be used in the practice of the present invention. The average molecular weight of the surfactants selected for the present invention may vary from about 200 grams / mol to more than 50,000 grams / mol. Preferred surfactants have an average molecular weight of from about 300 to about 50,000 grams / mole. The level of surfactant initially mixed with the polymeric resin before the formation of the film can be as much as 10% by weight of the total resin / surfactant mixture. Surfactants can be added in the preferred average molecular weight scale (300-50,000 grams / mole at lower levels, generally at or below about 5% by weight of the total structure of the film). The polymeric film that is formed prior to perforation can be processed using conventional methods to produce films in conventional extruded filmmaking equipment. It can be first mixed dry, pellets of the components described above (including the surfactant and one or more polymers in the pellet form) and then melting the mixture in the extruder. Alternatively, if insufficient mixing occurs within the extruder, the pellets and the surfactant can be first mixed dry and then melt mixed in a precomposing extruder followed by regranulation prior to extrusion of the film. In general, polymers can be processed in the molten state in films using either cast or blown film extrusion methods, both of which are described in "Plastics Extrusion Technology" - Second Edition, by Alian A. Griff ( Van Nostrand Reinhold - 1976), incorporated herein by reference. The cast film is extruded through a linear slot die. Generally, the flat web is cooled on a large roller of polished metal in motion. This rapidly cools and detaches from the first roller, passes over one or more auxiliary rollers, and then through a set of rubber-coated pulleys or "carry" rollers, and finally into a furler. In the extrusion of the blown film, the molten material is extruded upwards through a thin annular die opening. This process is also referred to as tubular film extrusion. Air is introduced through the center of the die to inflate the tube and cause it to expand. A moving bubble is then formed, which is maintained at a constant size by the control of the internal pressure of the air. The tube of the film is cooled by a stream of continuous air from one or more cooling rings surrounding the tube. The tube is then collapsed or crushed, stretching it to a flattening frame through a pair of pulley rollers and towards a furler.

"I- Formation of permanently wettable, apertured polymeric plots The process of the present invention provides for single-ply, durably wettable plies, preferably having either a macro-size or micro-sized aperture, or both of the apertures of macro size and micro size Without considering the desired final product, applicants have discovered that in order to reduce carryover of the migratable surfactant during hydroforming, drilling must be accomplished prior to the migration of a significant portion of the surfactant towards the surface of the polymer film For a given combination of polymer / surfactant, the speed at which the surfactant will migrate towards the surface of the polymeric film (and thereby reduce the contact angle for water) is a function of several factors, including the thickness of the film, the nature of the surfactant, (such as the molecular structure), polarity, compatibility with the resin, molecular weight, chemical structure, etc., the concentration of the surfactant in the polymer, the temperature at which the impregnated polymer is stored with the surfactant after extrusion, the of extrusion (e.g., extrusion temperature) and the nature of the matrix of the polymer resin (e.g., crystallinity). For a given mixture of surfactant / polymer, the rate of migration of the surfactant towards the surface of the film will generally increase with the increase in temperature and decrease with the decrease in temperature. The skilled artisan will recognize that routine experimentation, using the methods described in the Test Methods section, will allow the determination of when the drilling should be performed for a given combination of surfactant / polymer to be processed to achieve the perforation when the contact angle for the water of the material is at least approximately 30 degrees. As discussed in detail here, the critical point is that with respect to the processing of the films they have, whether they are macro or micro size holes, the perforation must be done at the moment when the non-perforated film (containing polymer and surfactant) have a contact angle for water of approximately at least 30 degrees, preferably at least about 40 degrees, more preferably at least about 50 degrees. With respect to films having both macro apertures and micro apertures, the hydroformation of the first set of apertures must be formed when the essentially continuous film has a contact angle for water of at least about 30 degrees. Preferably at least about 40 degrees, more preferably at least 50 degrees; and the final micro or macro perforation, should be performed when the film with macro or micro openings has a contact angle for water of at least about 30 degrees, preferably at least about 40 degrees, more preferably at least about 50 degrees ( As indicated above, the synchronization of the second phase of the formation of openings is determined by the measurement of the contact angle of the surface that will be exposed to the fluid pressure differential during the next (second) phase, of the formation of openings This is the surface that is in contact due to the high pressures of fluid and this is what is subjected to the drag of the surfactant). Known methods for the formation of openings using the fluid pressure differential are useful here, as long as drilling is conducted within the period after extrusion of the film which is found to be critical by the applicants. Preferred, non-limiting modalities are discussed below. A particularly preferred multi-phase formation process of the present invention is illustrated schematically in Figure 1 in U.S. Patent No. 4, 609,518, issued September 2, 1986 to Curro et al. (Hereinafter "patent 518"), which is incorporated by reference herein. In essence, the forming process illustrated in Figure 1 of the 518 patent and discussed further with respect to Figures 2-4 can be used in the present invention, while the formation of openings in the non-perforated web 10 in the structure of formation 15 occurs before the non-perforated web has a contact angle for water of about 30 degrees and the final aperture formation in structure 50 of the apertured web 10 (in accordance with the present invention), comprising, for example, a polymeric material such as a polyethylene or polypropylene and a migratable surfactant) formed in the forming structure 15 is conducted when the surface of the apertured web coming from the forming structure 15 will not be in contact with the structure. 50, have a contact angle for water of at least about 30 degrees, as measured by the method described in section n Test Methods. The formation of the micro-openings in the first phase and the formation of the macro-openings in the second phase, by the patent 518 is preferred. However, reversing the order of the formation of openings is possible and is within the scope of the present invention. From Figure 1 of the 518 patent, after completing the first phase of the weave formation process in the forming structure 15 the aperture screen 10 of the polymer / surfactant mixture can be fed to the second stage of the process. Training for additional drilling or to a winding station for temporary storage. In the latter circumstance, the application of the second phase of the process may be deferred until a later date, perhaps in a different location. As noted above, however, the application of the second phase must be conducted when the web 10 coming from the first drilling phase in the forming structure 15 exhibits a contact angle for water of at least about 30 degrees. Figure 5 of the 518 patent is a simplified illustration of an alternating polymeric screen formation process, which may be used in the present invention. As the process generally illustrated in Figure 1, the process shown in Figure 5 is carried out in two discrete phases. As can be seen from a comparison of Figures 5a and 5b to Figures 1a and 1c, respectively, the first phase of the process provides micro size openings 11 in the weft of the film 10 (containing the polymer and the migratable surfactant when adopted to the present invention) essentially identical. However, in the embodiment shown in Figure 5, the surfactant polymer polymer film is fed directly onto a second forming structure identical to that shown in Figure 1, without the reverse wrapping of the film. Accordingly, the surface 17 is placed in contact with the forming structure 50, while the surface 14 is positioned in such a manner that it will be in contact with the liquid jet 100 emerging from a fluid nozzle 90. With the exception of the inverting the position of the fixed deflectors 70 and 80 and reversing the direction of rotation of the forming structure 50 around the forming drum 58, the second phase of the process shown in Figure 5 is substantially identical to that shown in FIG. Figure 1. Again, in adapting the process shown in Figure 5, the macroscopic perforation in the forming structure 50 must happen when the surface of the micro-aperture weft 10 comes from the first perforation phase that will not be in contact with the forming structure 50, exhibit a contact angle for water of at least about 30 degrees. Reversing the order to form the first macro openings, followed by the formation of the micro open, is within the scope of the present invention. Despite the advantages achieved through the use of multiple formstructures in carryout the multi-phase frame formation process of the present invention, there may be circumstances when it is particularly desirable to practice the present invention usonly one structure of three-dimensional formation. These situations may involve the production of polymeric webs where it is desired to provide macroscopic expansion to form relatively large open in combination with the micro size perforation of the web only in the moorareas without low relief of the web, i.e. Lateral walls of the capillary networks would remain substantially undrilled. It may also be desirable in certain examples to provide macroscopic conformity of a plastic web to the three-dimensional patterns of the formstructure with only the micro-size perforation instead of the macro-size perforation in the end walls of the capillary networks formed in the plot. In still other situations, it may be desirable to provide the micro size perforation in the end walls of the capillary networks in combination with the micro size perforation in the moorareas without low relief of the weft without micro size perforation in the side walls. of capillary networks. The multiple phase process modalities illustrated in Figures 6, 8, 9 and 10 of the patent 518 are illustrative of the multi-phase formation processes of the present invention that are carried out using a single forming structure that contains not only the desired profile of the macroscopic cross-section, but also the desired micro-scale perforation pattern. . Of course, where the durably wettable web having only micro sized or macro size openings is desired, the steps described in the '518 patent for micro or macro perforation, respectively, can be eliminated. For the present invention, this perforation must be completed when the web 10 of the polymer / surfactant mixture has a contact angle for water of at least 30 degrees. For the production of durably wettable plies having only micro size openings, the film formation can be alternately conducted in accordance with the processes described in U.S. Patent No. 4,629,643, issued December 16, 1986 to Curro et al. (Hereinafter "patent 643), which is incorporated by reference herein." The plots of the present invention may also be prepared using the processes generally described in the US patent.

United States No. 4,695,422 issued September 22, 1987 to Curro et al., The disclosure of which is incorporated by reference herein. Again, those processes are modified in accordance with the teachings herein with respect to the timing of the formation of the openings. The details regarding the construction, placement, etc., of the nozzle for drilling with fluid, are fully set forth in patents 518, 643 and 422. For purposes of drilling the wefts of the type described herein, the jet nozzle of High pressure liquid is typically operated at a pressure on the scale of approximately 400 psig to approximately 1200 psig. The webs of the present invention are optionally subjected to the corona discharge treatment at any point in the post-extrusion manufacturing process of the polymer / surfactant, to form the continuous web, without openings.

In this way, for example, the corona discharge treatment can, when desired, occur before the formation of the openings, after the final formation of the openings, or between the phases of formation of the openings when they are used more of a phase. The use of the corona discharge treatment can provide the wefts of the present invention with increased durable wetting capacity. Methods for the corona discharge treatment of polymeric films is well known in the art. (See, for example, corona treatment, a summary, "Markgraf, D.A. TAPPI SEMINAR NOTES - 1986 COEXTRUSION, pages 85 to 91).

IV. Permanently wettable aperture screens With the exception of being composed of polymeric material (e.g., polyolefins) and impregnated surfactant, the preferred apertured plots of the present invention will have structural appearances similar to the plots described in the patents 518, 643 and 422. Frames having only micro sized openings can have a structure similar to that depicted as Figure 1C in the '518 patent. Preferred frames of the present invention have both macroscopic and microscopic openings, such as the plots shown in FIG. Figure 1E, 5D, 6C, 9C and 10C of the 518 patent. Most preferably, the microscopic openings are formed in a direction opposite to the macroscopic openings, as depicted in Figure 1E of the 518 patent. particularly preferred, the screen with double openings will have a caliber of approximately 750 μm.

V. Absorbent Articles As used herein, the term "absorbent article" generally refers to the devices used to absorb and contain body exudates., and more specifically refers to devices that are placed against or close to the body of the user, to absorb and contain the various discharged exudates 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 otherwise restored or reused as an absorbent article (ie, they are intended to be disposed of after limited use). and, preferably, be recycled formed in compost or arranged in another in an environmentally compatible manner A "unitary" absorbent article refers to absorbent articles that are formed as a single structure or as a separate part joined together to form an entity coordinated, in such a way that they do not require separate manipulated parts such as a separate bra and pads A preferred embodiment of a unitary disposable absorbent article made in accordance therewith is the catamenial pad, sanitary napkin 10, shown in Figure 1. As used herein, the term "sanitary napkin" refers to an absorbent article that is used by women adjacent to the pudendal region, generally external to the genitourinary region, and which is intended to absorb and contain the menstrual fluids and other vaginal discharges of the wearer's body. For example, blood, menstruation and urine. Devices between the lips that reside partially inside and partially outside the wearer's vestibule are also within the scope of the present invention. However, it should be understood that the present invention is also applicable to other pads for feminine hygiene or to catamenial pads or other absorbent articles such as diapers, incontinence pads, training pants and the like, as well as other wefts designed to facilitate the transporting fluid away from a surface such as disposable towels, facial diapers, cleaning towel and the like. It should be understood that the size, shape, and / or general configuration of the absorbent article if any, in which the wefts according to the present invention are incorporated, or are used in combination with, have no functional critical point relationship with the principles of the present invention. However, these parameters must be considered together with the fluid attempted and the functionality attempted when determining the appropriate configurations of the frame. The sanitary napkin 10 is illustrated as having two surfaces, a first surface 10a, sometimes referred to as the surface facing towards or contacting the wearer, a surface facing toward or in contact with the body or "body surface". , and the second surface 10b (shown in Figure 2) sometimes referred to as the contacting or facing surface of the garment or "pledge surface". The sanitary towel 10 is shown in Figure 1, or seen from its first surface 10a. The first surface 10a is intended to be used adjacent to the wearer's body. The second surface 10b of the sanitary napkin 10 (shown in Figure 2) is on the opposite side and is intended to be placed adjacent to the wearer's undergarment when the sanitary napkin 10 is used. Referring to Figure 1, the Sanitary pad 10 has two center lines, a longitudinal center line "L" and a transverse center line "T". The term "longitudinal", as used herein, refers to a line, axis or direction in the plane of the sanitary napkin 10 that is generally aligned with (eg, approximately parallel to) a vertical plane that divides a standing user in left and right body halves when the sanitary pad is used 10. The terms "transverse", or "lateral", as used herein, are interchangeable and refer to a line, axis or direction that is located within the plane of the sanitary napkin 20, which is generally perpendicular to the longitudinal direction. Figure 1 also shows that the sanitary napkin 10 has a periphery 20, which is defined by the outer edges of the sanitary napkin 10, in which the longitudinal edges 21 (or "lateral edges") are designated and designated 22 to the extreme edges (or "extreme"). Figure 1 is a top plan view of a sanitary napkin 10 of the present invention in a substantially flat state, with part of the sanitary napkin being cut to show more clearly the construction of the sanitary napkin 10 and with the part of the sanitary napkin 10 sanitary towel 10 facing towards or in contact with the user 10a facing the observer. As shown in Figure 1, the sanitary napkin 10 comprises a liquid-permeable top sheet 12 of the present invention, a liquid-impermeable backsheet 13 joined with the topsheet 12, an absorbent core 14 positioned between the topsheet 12 and the backsheet 13, a secondary topsheet or acquisition layer 15 positioned between the topsheet 12 and the absorbent core 14. The sanitary napkin 10 preferably includes optional side flaps or "wings" 24 that are folded around the crotch portion of the backsheet. the wearer's panties. The side flaps 24 can serve a number of purposes, including, but not limited to, helping to keep the towel in the proper position while protecting the wearer's panties from stains and keeping the sanitary napkin secured to the pant. of the user. Figure 2 is a cross-sectional view of the sanitary napkin 10 taken along the section line 2-2 of Figure 1. As can be seen in Figure 2, the sanitary napkin 10 generally includes a holding means adhesive 26 for fixing the sanitary towel 10 to the wearer's undergarment. The removable release liners 27 protect the adhesive fastening means 26 to prevent the adhesive from sticking to a different surface of the crotch portion of the undergarment prior to use. The topsheet 12 has a first surface 12a and a second surface 12b positioned adjacent to and preferably secured to a first surface 15a of the fluid acquisition layer 15 to promote fluid transport from the topsheet to the acquisition layer. The second surface of the acquisition layer 15 is positioned adjacent to and preferably secured to the first surface 14a of an absorbent core or fluid storage layer 14, to promote fluid transport from the acquisition layer to the absorbent core. The second surface 14b of the absorbent core 14 is positioned adjacent to and preferably secured to the first surface 13a of the backsheet 13. In addition to having a longitudinal direction and a transverse direction, the sanitary napkin 10 also has a "Z" direction or axis, which is the direction proceeding down through the top sheet 12 and to either side of the fluid storage layer or core 14 that can be provided. The object is to provide a substantially continuous path between the topsheet 12 and the underlying layer or layers of the absorbent article, such that the fluid is entrained in the "Z" direction and away from the top sheet of the article and toward its backing layer. final storage. The absorbent core 14 may be any absorbent means that is capable of absorbing or retaining the liquids (e.g., menstruation and / or urine). As shown in Figure 2, the absorbent core 14 has a body surface 14a a garment facing surface 14b, side edges and end edges. The absorbent core 14 can be manufactured in a wide variety of sizes and shapes eg, rectangular, oval, hourglass, dog bone, asymmetric, etc.), and from a wide variety of liquid absorbent materials commonly used in sanitary napkins and other absorbent articles such as crushed wood pulp, which is generally referred to as an air filter. Examples of other suitable absorbent materials include accreted cellulose wadding; meltblown polymers, including coform; chemically hardened, modified, or crosslinked cellulosic fibers, synthetic fibers, such as crimped polyester fibers, peat moss, tissue, including tissue envelopes, and tissue laminates; absorbent foams; absorbent sponges; superabsorbent polymers, absorbent gelling materials; or any equivalent material or combinations of materials or mixtures thereof. The configuration and construction of the absorbent core can also be varied (for example, the absorbent core can have zones of variable gauge (for example, profiled to be thicker in the center), hydrophilic gradients, superabsorbent gradients or lower density acquisition zones or lower average basis weight, or may comprise one or more layers or structures). The total absorbent capacity of the absorbent core, however, must be compatible with the design load and intended use of the absorbent article. In addition, the size and absorbent capacity of the absorbent core can also be varied to encompass the different uses such as incontinence pads, pantiliners, regular sanitary napkins, or nighttime sanitary napkins. Exemplary absorbent structures for use as the absorbent core in the present invention are described in U.S. Pat. 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; and in European patent application 0 198 683, Procter & Gamble Company, published on October 22, 1986 in the name of Duenk and others. The disclosure of each of these patents is incorporated herein by reference. The backsheet 13 and the topsheet 12 are positioned adjacent the garment facing surface and the body facing surface, respectively of the absorbent core 14 and are preferably attached to it and to each other by attachment means (not shown). ), such as those well known in the art. For example, the backsheet 13 and / or the topsheet 12 can be secured to the absorbent core or to each other by a continuous uniform adhesive layer, a patterned adhesive layer or any array of separate lines, coils or dots of adhesives. The adhesives that have been found to be satisfactory are manufactured by H.B. Fuller of St. Paul Minnesota under the designation HL-1258, and by Findlay of Minneapolis, Minnesota under the designation H-2031. The attachment means preferably will comprise an open pattern web of adhesive filaments as disclosed in U.S. Patent No. 4,573,986 issued to Minetola et al. On March 4, 1986, the disclosure of which is incorporated herein by reference. . An exemplary joining means of an open pattern network of filaments comprises several lines of adhesive filaments twisted in a spiral pattern as illustrated by the apparatus and methods shown in U.S. Patent No. 3,911,173 issued to Sprague, Jr. ., on October 7, 1975; U.S. Patent No. 4,785,996 issued to Zieker et al., November 22, 1978 and U.S. Patent No. 4,842,666 issued to Werenicz on June 27, 1989. The disclosures of each of these patents are incorporated herein. by reference. Alternatively, the joining means may comprise heat bonds, pressure joints, ultrasonic joints, mechanical dynamic joints or any other suitable joining means or combination of these joining means as are known in the art. The backsheet 13 is impervious to liquids (eg, menstruation and / or urine) and is preferably manufactured from a thin plastic film although other flexible liquid impervious materials may also be used. As used herein, the term "flexible" refers to materials that are docile and will more readily conform to the shape and general contour of the human body. The backsheet 13 prevents the exudates absorbed and contained within the absorbent core from moistening the articles that are in contact with the sanitary pad 10 such as underpants, pajamas and undergarments. The backsheet 13 can thus comprise a woven or non-woven material, polymeric films such as polyethylene or polypropylene thermoplastic films, or composite materials such as a film-coated nonwoven material. Preferably, the backsheet of the polyethylene film having a thickness of about 0.012 mm to about 0.051 mm. Exemplary polyethylene films are manufactured by Clopay Corporation of Cincinnati, Ohio, under the designation P18-1401 and by Tredegar Film Products of Terre Haute, under the designation XP-9818. The backsheet is preferably embossed and / or finished without gloss to provide a more fabric-like appearance. In addition, the backsheet 13 can allow the vapors of the absorbent core 14 to escape (ie, breathable, while still preventing the exudates from passing through the backsheet 13. In use, the sanitary napkin 10 can be maintained in the place by any means of support or fixing means (not shown) well known for these purposes., the sanitary towel is placed on the wearer's underpants or panties and secured by an adhesive. The adhesive provides a means for securing the sanitary napkin in the crotch portion of the panty. Therefore, a part or all of the surface facing the garment or external 13b of the backsheet 13 is coated with adhesive. Any adhesive or adhesive glue or glue used in the art for this purpose can be used for the adhesive herein, with pressure sensitive adhesives being preferred. The suitable adhesives are manufactured by H.B. Fuller Company, of St. Paul Minnesota, under the designation 2238. Suitable adhesive fasteners are also described in U.S. Patent No. 4,917,697. Before the sanitary napkin is put into use, the pressure sensitive adhesive is typically protected with a removable release liner 27 in order to prevent the adhesive from drying or adhering to a different surface of the crotch portion of the panty before use. Suitable release liners are also described in the aforementioned U.S. Patent No. 4,917,697. Any of the commercially available release liners, commonly used for these purposes, can be used herein. A non-limiting example of a suitable release liner is BL30MG-A Silox 4P / O, which is manufactured by Akrosil Corporation of Menasha, Wl. The sanitary napkin 10 of the present invention is used when removing the release liner and subsequently placing the sanitary towel in a panty, in such a way that the adhesive is in contact with the panty. The adhesive holds the sanitary napkin in its position inside the pant during use. In a preferred embodiment of the present invention, the sanitary napkin has two fins 24 each of which are adjacent to and extend laterally from the lateral edge of the absorbent core. The fins 24 are configured to fold over the edges of the wearer's panties in the crotch region, so that the fins are arranged between the edges of the panties and the thighs of the wearer. The fins serve at least two purposes. First, the fins help to avoid the staining of the body and the wearer's panties by the menstrual fluid, preferably forming a double-walled barrier along the edges of the panty. Second, the flaps are preferably provided with a fastening means on their garment surface such that the flaps can fold back under the panty and join the garment-facing side of the panty. In this way, the fins serve to keep the sanitary napkin properly positioned within the pant. The fins can be constructed of various materials, including materials similar to the top sheet, the back sheet, tissue or combination of these materials. In addition, the fins may be a separate element attached to the main body of the towel or may comprise extensions of the upper sheet and the backsheet. That is, 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 18 August 1987; and 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 15 can be placed between the topsheet 12 and the absorbent core 14. The acquisition layer 15 can serve several functions including improving the capillary action of the exudates on and towards the absorbent core. There are several reasons why the improved capillary action of the exudates is important, including providing a more even distribution of the exudates throughout the absorbent core and allowing the sanitary napkin 10 to be made relatively thin. The capillary action referred to herein may encompass the transport of liquids, in one, two or in all directions (ie, in the x-y plane and / or in the 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. Examples of sanitary napkins having an acquisition layer and a topsheet are more fully described in the US patent.

United States No. 4,950,264 issued to Osborn and in United States Patent Application Serial No. 07 / 810,774, "Absorbent article having melted layers", filed on December 17, 1991 in the name of Cree et al. The disclosures of each of these references are hereby incorporated by reference. In a preferred embodiment, the acquisition layer may be attached to the upper sheet by any of the conventional means for joining frames together, most preferably by melt links as described more fully in the above-referenced Cree application. The catamenial pads can be constructed as follows. On a release paper coated with silicone, a spiral pattern of the H2031 Findley thermal fusion adhesive is applied at 0.04 grams per inch2. This layer of adhesive is transferred on the upper side (facing the user) of a secondary upper sheet by winding the secondary upper sheet, and the release paper coated together with a manual roller. The secondary topsheet is formed of a nonwoven material known as Fort Howard tissue placed with air, grade, commercially available as Grade 817 commercially available from Fort Howard 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 by gently pressing them together with a manual roller. Two quarter-inch double-sided tape strips are applied along both long edges of a polyethylene backsheet. The core is added to build the complete absorbent structure.

To construct a representative absorbent article according to the embodiment of Figure 3, the following materials are used for the components of the absorbent structure. The absorbent article of Figure 3 (catamenial pad) is structurally similar to those of Figures 1 and 2, except that it exhibits a general hourglass-shaped profile. The core layer is assembled as follows: a sheet of the same Fort Howard material is cut as the top sheet secondary to a finished size of 190 mm by 143 mm. A silicone coated release paper containing a spiral pattern of the H2031 Findaly thermal fusion adhesive is applied to the Fort Howard at 0.04 grams per square inch. The silicone-coated release paper used to transfer the glue is left on the Fort Howard, and a 190 mm by 65 mm template is placed over the middle of the sheet with the longitudinal ends aligned with the longitudinal ends of the Fort Howard . The Fort Howard then folded over the template to fold the material, dividing the material into three parts. The template is then removed, leaving the glue on the folded Forth Howard. The particulate absorbent gelling material in the form of Nalco 1180 AGM is then evenly distributed in the amount of 0.68 grams per pad on the glue side of the Fort Howard nonwoven. Next, a quarter-inch 190 mm double-sided tape is applied to the edge of the inside of the Fort Howard, which is then folded over the folds in such a way that the edge with the tape is over the top. The resulting storage core has a finished dimension of 190 mm by 65 mm.

The secondary upper sheet is adhesively attached to the upper sheet. The storage / core layer is adhesively bonded to the polyethylene backsheet by two quarter-inch strips of the double-sided tape. The assembly of the upper sheet and the absorbent structure are then combined. Next, a sheet of Teflon ® is placed on the assembled structure.

The edges of the product are sealed with an appropriately formed die, fixed to a plate and heated to a temperature above the melting point of the top sheet and the polyethylene backsheet. The iron die is applied to the material with manual pressure to seal the edges. The catamenial pad is then cut to remove the excess material using a pair of hand scissors. A representative embodiment of a disposable absorbent article in the form of a diaper 100, is shown in Figure 4. 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, sanitary napkins, facial papers, paper towels and the like. The diaper 100 shown in Figure 4 is a simplified absorbent article that can represent a diaper before it is placed on a wearer. However, it should be understood that the present invention is not limited to the particular type or particular configuration of the diaper shown in Figure 4. Figure 4 is a perspective view of the diaper 100 in its non-contracted state (ie, with all the contraction induced by the elastic removed), with parts of the structure that are cut to show more clearly the construction of the diaper 100. The part of the diaper 100 that is in contact with the wearer giving the observer. The diaper is shown in Figure 4 to comprise a liquid-permeable topsheet 104 of the present invention; a liquid impermeable backsheet 102 joined to the topsheet 104; and an absorbent core 106 positioned between the topsheet 104 and the backsheet 102. Additional structural features such as elastic members and fastening means for securing the diaper in place on a wearer (such as tape tab fasteners) , they can also be included. Although top sheet 104, backsheet 102 and absorbent core 106 can be assembled in a variety of well-known configurations, the preferred diaper configuration is generally described in United States Patent No. 3,860,003 (Buell), issued on January 14, 1975, the disclosure of which is incorporated by reference. Alternately preferred configurations for disposable diapers 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. Figure 4 shows a preferred embodiment of the diaper 100, in which the topsheet 104 and the backsheet 102 are co-extensive and have length and width dimensions generally greater than those of the absorbent core 106. The topsheet 104 is joined with and overlays on the backsheet 102 thus forming the periphery of the diaper 100. The periphery defines the outer perimeter or the edges of the diaper 100. The periphery comprises the end edges 101 and the longitudinal edges 103. As indicated, the topsheet 104 of FIG. the present invention is preferably deformable, soft feeling, and non-irritating to the wearer's skin. The backsheet 102 is impervious to liquids and is preferably manufactured from a thin plastic film, although other flexible liquid impervious materials may also be used. The backsheet 102 prevents the exudates absorbed and contained within the absorbent core 106 from wetting articles that are in contact with the diaper 100, such as sheets and undergarments. Preferably, the backsheet 102 is the polyethylene film having a thickness of about 0.012 mm to about 0.051 cm, although other flexible liquid impervious materials may be used. As used herein, the term "flexible" refers to materials that are docile and that will readily conform to the outline and general shape of the user's body. A suitable polyethylene film is manufactured by Monsanto Chemical Corporation and marketed as No. 8020 film in the market. Backsheet 102 is preferably embossed and / or finished without gloss to provide a more fabric-like appearance. In addition, the backsheet 102 can allow the vapors of the absorbent core 106 to escape while still preventing the exudates from passing through the backsheet 102. The size of the backsheet 102 is dictated by the size of the absorbent core 106 and by The exact design of the selected diaper. In a preferred embodiment, the back sheet 102 has a modified hourglass shape extending beyond the absorbent core 106 at a minimum distance of at least about 1.3 cm to about 2.5 cm around the total periphery of the diaper. The top sheet 104 and the back sheet 102 are joined together in any suitable manner. As used herein, the term "attached" encompasses configurations by which it directly attaches to the topsheet 104 to the backsheet 102 by attaching the topsheet 104 directly to the backsheet 102, and configurations by which it is indirectly bonded the upper sheet 104 to the back sheet 102 by attaching the back sheet 104 to intermediate members, which in turn are affixed to the back sheet 102. In a preferred embodiment, the upper sheet 104 and the rear sheet 102 are fixed directly yes at the periphery of the diaper by fixation means (not shown) such as an adhesive or any other means of attachment as is known in the art. For example, a continuous uniform adhesive layer, a patterned adhesive layer or a line array, or separate adhesive spots, may be used to secure the upper sheet 104 to the back sheet 102. The tape tab fasteners (FIG. not shown for clarity), are applied directly to the back waistband region of the diaper 102 to provide a fastening means for holding the diaper on the wearer. The tape tab fasteners can be any of those well known in the art, such as the fastener tape disclosed in United States Patent No. 3,848,594 (Buell), issued November 19, 1974, the disclosure of the which is hereby incorporated by reference. These tape tab fasteners or other diaper fastening means are typically applied near the corners of the diaper 100. The elastic means (also not shown for clarity), are disposed adjacent the periphery of the diaper 100, preferably along the length of the diaper. each longitudinal edge 103, such that the elastic members tend to pull and hold the diaper 100 against the user's legs. Alternatively, the elastic members may be disposed adjacent to either or both of the end edges 101 of the diaper 100, to provide a waistband as well as or instead of the leg cuffs. For example, a suitable waistband is disclosed in U.S. Patent No. 4,515,595 (Kievit et al.), Issued May 7, 1985, the disclosure of which is hereby incorporated by reference. In addition, a suitable method and apparatus for making a disposable diaper having elastically contractible elastic members is described in U.S. Patent No. 4,081, 301 (Buell), issued March 28, 1978, the disclosure of which is hereby incorporated herein by reference. The elastic members are secured to the diaper 100 in an elastically contractible condition such that in a normally unrestricted configuration, the elastic members will effectively contract or pick up the diaper 100. The elastic members can be secured in an elastically contractible condition at less two ways. For example, the elastic members can be stretched and secured while the diaper 100 is in an uncontracted condition. Alternatively, the diaper may be contracted, for example, by gluing it and the elastic members secured and connected to the diaper 100 while the elastic members are in their non-relaxed or unstretched condition. The elastic members may extend along a portion of the length of the diaper 100. Alternatively, the elastic members may extend to the full length of the diaper 100, or any other suitable length to provide an elastically shrinkable line. The length of the elastic members is dictated by the design of the diaper. The elastic members can be in a multiplicity of configurations.

For example, the width of the elastic members can be varied from about 0.25 mm to about 25 mm or more; the elastic members may comprise a single strand of elastic mateiral or may comprise several parallel or non-parallel strands of elastic material; or the elastic members may be rectangular or curvilinear. Still further, the elastic members may be fixed to the diaper in any of several maenras known in the art. For example, the elastic members can be ultrasonically bonded, sealed with heat and pressure on the diaper 100 using a variety of bonding patterns or the elastic members can simply be glued to the diaper 100. The absorbent core 106 of the diaper 100 is placed between the upper sheet 104 and back sheet 102. Absorbent core 106 can be manufactured in a wide variety of sizes and shapes (eg, rectangular, hourglass, asymmetric, etc.). The total absorbent capacity of the absorbent core 106 should, however, be compatible with the design liquid loading for the intended use of the absorbent article or diaper. In addition, the size and absorbent capacity of the absorbent core 106 can be varied to encompass users ranging from babies to adults.

As shown in Figure 4, the absorbent core 106 includes a fluid distribution member 104. In a preferred configuration as illustrated in Figure 4, the absorbent core 106 preferably further includes an acquisition layer or member 110 in communication. of fluid with the fluid distribution member 108 and located between the distribution member 108 and the top sheet 104. The acquisition layer or member 110 may be composed of several different materials including woven or non-woven webs of synthetic fibers including polyester , polypropylene or polyethylene, natural fibers including cotton or cellulose, mixtures of these fibers or any of the equivalent materials or combinations of materials. In use the diaper 100 is applied to a wearer by placing the waistband back region under the wearer's back, and pulling the rest of the diaper 100 between the legs of the wearer such that the waistband front region is placed across the front. of the user. The tape tab or other fasteners are then preferably secured in the outward facing areas of the diaper 100.

SAW. Test Method - Measurement of the Angle of Contact A. Non-perforated films The contact angle formed between the solid surface of a film without openings and the crescent of a water drop is a measure of the hydrophilic / hydrophobic capacity of the solid substrate . The contact angle with the smaller water, the greater hydrophilic capacity of the substrate. The method described below to determine the contact angle, and more specifically the time at which the contact angle for a given polymer / surfactant mixture is going to be processed is at least 30 degrees, allows the determination when a plan film No opening should be subjected to a first drilling process in accordance with the present invention.

An NRL model goniometer (Rame-Hart, Inc., Mountain Lake, NJ) can be used to measure the contact angle. A drop of ionized water of 4μL is placed on a sample of the flat film (without openings), seating it on the goniometer platform to measure the contact angle at room temperature. The goniometer is first calibrated using a spirit level to ensure that the sample platform is level. The light of the instrument is adjusted in such a way that the drop is clearly visible. A drop of 4μL ionized water is placed on a 3/8 inch piece of Lwxan® (available from General Electric) that has been previously washed with methanol and allowed to dry completely. The contact angle of the drop is measured. The instrument is calibrated appropriately if the contact angle of the water on the Lexan falls within the 68 +/- 3 degree scale. The measurements of the sample are obtained according to the following procedure: 1) A representative sample of a screen is cut without openings, the sample having dimensions of approximately 2.5 cm x 5 cm. 2) Place the sample on the sample platform. Adhesive tape is used, if necessary to secure the sample on the platform and keep the sample flat. 3) Place a drop of 4μL deionized water on the sample. 4) Adjust the position of the platform, vertically and horizontally and focus to get a clear view of the drop. 5) The contact angle is measured and recorded after the drop has been on the sample for at least two minutes, to ensure the balance of the sample. 6) Steps 1 to 5 are repeated three times for each sample tested. 7) The average of the contact angle for each sample is calculated. Contact angle measurements for a film without an aperture given after extrusion are obtained at different times until it is determined when the frame has a contact angle for water of at least about, for example 30 degrees. This will define the time at which the formation of the aperture of the film without openings must have occurred to minimize the entrainment of the surfactant.

B. Previously perforated films i. Openings formed in opposite directions In those modalities where a second phase of formation of openings is going to be conducted in the opposite direction to the first phase of the formation of openings, the time determined according to section VI-A for the flat film will apply to the previously perforated film. That is, where the formation of the aperture will occur in the opposite directions, both phases of the aperture formation must occur within the time after extrusion of the polymer / surfactant, determined for the flat film. This is explained by the fact that during the formation of the openings in the first phase, the male side (i.e., the side which makes contact with the forming structure), of the apertured weft will be exposed essentially to no pressure at all. fluid during the formation of the opening in the second phase (although there may be a minimum drag of, for example, indirect fluid contact), as such, relatively little of the surfactant molecules that have surfaced towards the surface of the screen ( male side), before the perforation of the flat film will be dragged. Therefore, the male side of the weft with openings in the first phase, will be exposed to the regions of the fluid in the second phase, will have a contact angle, at any given moment, essentially equal to a frame without openings. By way of illustration, if it is determined in section VI-A that a continuous continuous polymer / surfactant web should be drilled, within, for example, five hours after extrusion of the film to ensure that the angle of contact is not less than about 30 degrees, and the openings will be formed in opposite directions, then both phases of the opening formation must be conducted within five hours of film extrusion. ii. Openings formed in the same direction In those modalities where a second phase of openings is going to be conducted in the same direction, such as the first phase of the formation of openings, the following procedure is used to determine when each phase of the openings should occur. formation of openings to reduce drag. For purposes of determining the contact angle (and corresponding moments of drilling for the second drilling phase), the non-perforated film is processed on a forming structure having the desired aperture patterns, as well as the regions that have no openings . The total surface of the non-perforated film is exposed to fluid jets, resulting in a screen with openings having open patterns similar to those of the forming structure, as well as regions without openings. Because the non-perforated regions are exposed to the fluid pressures in the first formation structure, the contact angle of the surface measured in those regions will be essentially the same as the contact angle of the surface with openings that will be subjected to Water pressures during the second phase of the formation of openings. The procedure described in section VI-A above is used to determine the contact angle of the apertured film, except that the sample used in step 1) is a one-inch-by-two-inch sample cut from a non-apertured region. Weft openings. As well, in step 2) the sample is placed on the sample platform in such a way that the drop of 4 μL deionized water is placed on the surface that was exposed to the water jets in the first phase of the open formation. It is believed that the description contained herein will allow a person skilled in the art to practice the present invention in many and varied ways. However, the following examples and exemplary embodiments establish for purposes of illustration.

EXAMPLE 1 Formation of a Durably Wettable Polymeric Pattern Having Micro and Macro Size Openings in Opposite Directions A resin mixture comprising low density polyethylene and surfactant (Atmer 100®), available from Tredegar Film Products (Richmond, VA) as X-15565, is fed to an extruder. This resin mixture provides an extruded film comprising about 1% surfactant, by total weight of the film. The extruder is a single screw extruder 24: 1 in length: diameter with a conventional polyethylene mixing screw (available from Egan Machinen /, NJ). The homogeneous molten material is supplied to a molding die of the flexible lip. The temperature in the matrix zone is set at 480 ° F. A flat film having a thickness of about 25 μm is attached to the quenching rolls at a line speed of about 200 feet per minute. When they pass to the treater, the corona discharge treatment (180 volts) is optionally applied to the surface in the film in which the macro size holes originate. After the edge of the film is removed by a trimmer, the film is slit and coiled in the roll form. A sample of the film without opening is cut from the finishing roll. The measurements of the contact angle on the film according to the description of the Test Method (Section VI-A) are conducted to determine when the formation of the openings should be conducted. It is determined that, for this film, the formation of the openings of the non-perforated web should be conducted within 14 hours of film formation (i.e., extrusion). From the description of section VI-B, because the second phase of the formation of openings conducted in a direction opposite to that of the first phase, the second phase should also be carried out within 14 hours of the extrusion of the film. The extruded flat film comprising the polyethylene and the surfactant is fed onto a forming screen at a rate of 200 feet per minute and subjected to a high pressure jet. The screen used is 80 mesh, to provide a grid with micro openings. The water temperature is 175 ° F and the pressure is 550 psi. The film with micro apertures is then wound onto a tension roller. The apertured film is wrapped upside down on a second forming screen at a rate of 150 feet per minute and subjected to the high pressure jet.

As indicated above, this drilling base of the process is conducted in a time no greater than 14 hours after extrusion of the film. The sieve used is the circular macro-aperture pattern 56/4, where the orifice diameter is 56 mils and the distance between the holes is 4 mils. The water temperature is 145 ° F and the pressure is 525 psi. The film with openings is dried, treated with corona discharge, then adjusted and cut into strips 8 inches wide and wound on two tension rollers.

EXAMPLE 2 Formation of a Durably Wettable Polymeric Pattern Having Micro and Macro Size Openings in Opposite Directions A resin mixture comprising low density polyethylene and surfactant (Atmer 100®), available from Tredegar Film Products (Richmond, VA) as X-15663, is fed to an extruder. This resin mixture provides an extruded film comprising approximately 2% surfactant, by total weight of the film. The extruder is a single screw extruder 24: 1 in length: diameter with a conventional polyethylene mixing screw. The homogeneous melt is delivered to a 44-inch wide flexible lip molding die. The temperature in the matrix zone is set to 480 ° F. A 25 μm thick flat film is attached to the quenching rolls at a line speed of approximately 200 feet per minute. While the treater passes, the corona discharge treatment (180 volts) is optionally applied to the surface of the film within which the macro size openings will originate. After the edge of the film is removed by a trimmer, the film is cut into strips and wound into the roll form. A sample of the film is cut from the finished roll. The measurements of the contact angle on the film according to the description of the Test Method (Section VI-A) are conducted to determine when the formation of the openings should be conducted. It is determined that for this film, the formation of the apertures of the non-perforated screen must be conducted within six hours of film formation (ie, extrusion). According to the description in section Vl-B above, because the second phase of the formation of openings is conducted in a direction opposite to that of the first phase, the second phase must also be carried out no more than 6 hours after the extrusion of the film.

The extruded flat film comprising the polyethylene and the surfactant is fed onto a forming screen at a rate of 200 feet per minute and subjected to a high pressure jet. The screen used is 80 mesh, to provide a grid with micro openings. The water temperature is 175 ° F and the pressure is 550 psi. The film with micro apertures is then rolled onto a tension roller. The apertured film is wrapped upside down on a second forming screen at a rate of 150 feet per minute and also subjected to the high pressure jet. As indicated above, this phase of drilling the process is condd at a time no greater than 6 hours after extrusion of the film. The sieve used is the circular macro-aperture pattern, where the diameter of the orifice is 56 mils and the distance between the holes is 4 mils. The water temperature is 145 ° C and the pressure is 525 psi. The film with openings is dried, treated with corona discharge, then adjusted and cut into 8-inch-wide strips and wound on two tension rollers. As demonstrated by a comparison of Examples 1 and 2, the resin / surfactant mixture containing 2% surfactant dictates that the formation of the openings occurs much sooner than mixing with the 1% mixed surfactant, in order to reduce the carryover of the surfactant according to the present invention.

Claims (1)

1- A process for forming a polymeric screen with durably wettable, single-layer openings, characterized in that the process comprises the steps of: (a) melting a mixture of at least one thermoplastic polymer and at least one migratable surfactant and extruding the mixture to form a substantially continuous polymer film; (b) continuously supporting the film on a forming structure exhibiting a multiplicity of openings which places the opposite surface of the forming structure in fluid communication with one another, moving the forming structure in a direction parallel to the direction of the movie trip and taking the film in the direction; and (c) applying a fluid pressure differential across the thickness of the film along the direction of movement of the forming structure that exhibits the openings, the fluid pressure differential being large enough to make the film Break in those areas that match the openings in the formation structure; characterized in that the formation of the openings in the passage (c) is performed when the surface of the substantially continuous film formed in step (a) has a contact angle for water of at least 30 degrees. 2. The process according to claim 1, characterized in that the thermoplastic polymer is a polyolefin, further characterized in that the thermoplastic polymer is selected from the group consisting of polyethylene, polypropylene and mixtures thereof. 3. The process according to any of claim 1 or 2, characterized in that the migratable surfactant is selected from the group consisting of sorbitan esters, silicone copolymers, fluorochemicals, and mixtures thereof, preferably the agent surfactant is sorbitan ester. 4. The process according to claims 1 to 3, characterized in that the migratable surfactant comprises up to 10% by weight of the mixture of thermoplastic polymer / migratable surfactant, preferably up to 5% by weight, of the mixture of thermoplastic polymer / migratable surfactant. 5. A multi-phase process for forming a polymeric frame with durably wettable, single-layer openings, the process comprising the steps of: (a) melting a mixture of at least one thermoplastic polymer and at least one surfactant migrable and extruding the mixture to form a substantially continuous polymeric film; (b) continuously supporting the film on a first forming structure that exhibits a multiplicity of openings that place the opposing surfaces of the forming structure in fluid communication with each other, moving the forming structure in a direction parallel to the direction of the trip of the film and taking the film in the direction; (c) applying a first fluid pressure differential through the thickness of the film along the direction of movement of the deformation structure exhibiting the openings, the fluid pressure differential being large enough to cause it to break film in those areas that match the formation openings; (d) continually supporting the apertured web on a second forming structure that exhibits a multiplicity of openings that place the opposing surfaces of the second forming structure in fluid communication with each other, moving the second forming structure in one direction parallel to the direction of the trip of the frame with openings and carrying the frame with 10 openings in the direction; and (e) applying a second fluid pressure differential through the thickness of the weft with openings along the direction of movement of the forming structure characterized in that the second fluid pressure direrential is sufficiently large 15 to break the web with openings in those areas that coincide with the openings in the second forming structure, while substantially maintaining the integrity of the openings formed by the first fluid pressure differential; characterized in that the formation of the openings in step (c) is performed when the film 20 formed in step (a) has a contact angle for water of at least 30 degrees, and further characterized in that the formation of openings in step (e) is carried out when the surface of the weft with openings formed in step (c) which will be subjected to the second fluid pressure differential in the second formation structure 25 has a contact angle for water of at least 30 °. 6. - The process according to claim 5, characterized in that one of the forming structures exhibits a multiplicity of microscopic openings and the other forming structure exhibits a multiplicity of macroscopic openings. 7. The process according to claim 6, characterized in that the web is micro-perforated on the first forming structure and is then fed on the second forming structure in such a way that the surface of the web that is in contact with the web. The first training structure is not in contact with the second training structure. 8. A polymeric and single-layer web comprising a thermoplastic polymer and a migratable surfactant, the first and second surfaces having the web, the web also comprising a multiplicity of microscopic openings originating in the first surface of the web and having a wall continuously interconnected lateral that extends in the direction of the second surface of the frame. 9. The single-layer polymeric web according to claim 8, further comprising a multiplicity of macroscopic openings to transmit the fluids that are deposited dynamically on the web, each of the macroscopic openings originating in the first surface of the web and having a continuously interconnected side wall extending in the direction of i) the second surface, or ii) a third surface remote from the first and second surfaces of the frame. 10. The single-layer polymeric frame according to claim 8 or 9, characterized in that each microscopic opening has as the largest dimension in the first surface of the weft, as measured perpendicular to its amplitude, a distance not greater than 300 μm. 1 - An absorbent article, preferably a catamenial pad, comprising: (a) a top sheet (b) a back sheet; and (c) an absorbent structure located between the topsheet and the backsheet; characterized in that the topsheet is prepared by the process according to any of claims 1 to 7. 12. An absorbent article, preferably a catamenial pad comprising: (a) a top sheet; (b) a back sheet; and (c) an absorbent structure located between the topsheet and the backsheet; characterized in that the top sheet is the polymeric web according to any of claims 8 to 10.