MXPA99005946A - Breathable disposable absorbent article for topical adhesive attachment to the skin of a wearer - Google Patents

Abstract

The present invention relates to breathable absorbent articles particularly sanitary napkins, pantiliners, adult incontinence products or sweat pads. In particular the present invention relates to such breathable absorbent articles which are worn by direct attachment to the skin of the wearer in the area were absorption of bodily liquids is desired.

Description

BREATHABLE DISPOSABLE ABSORBENT ARTICLE FOR TOPICAL FIXATION TO THE SKIN OF A USER FIELD OF THE INVENTION The present invention relates to breathable disposable absorbent articles, particularly sanitary napkins, pantyhose, adult incontinence products or sweat pads. In particular, the present invention relates to these disposable, breathable absorbent articles, which are used to fix them directly to the skin of the patient. user in the area where the absorption of bodily fluids is desired.

BACKGROUND OF THE INVENTION The prior art in this field of disposable articles for topical application to a user's skin is developed particularly in the field of auxiliary bandages, plasters and bandages. These articles, however, are typically applied in an emergency situation, where, for example, a wound has occurred on the user's skin and the absorption of body fluids emanating from a wound is desired. In this context, aspects of the performance of the absorbent article such as comfort and easy application and use, painless removal, discretion are subordinated to criteria such as sterility, protection of healing, mechanical protection of the wound. Also the absorbent articles that protect the wound are widely used in areas of the skin where the body hair can be removed before the application of the absorbent article where little or no hair grows.

The present invention is not related to breathable absorbent articles that protect wounds but are related to breathable absorbent articles for the absorption of body fluids which naturally emanate from a body without a wound. For example, sanitary pads or breathable pantiliners for use in the genital region are these items. Also, breathable incontinence devices, which are used, for example, in the genital region or breathable sweat pads that are used in the region of a person's armpit are the subject of the present invention. These articles are applied to the skin of a user in a region where a considerable amount of hair typically grows, so that the criteria of easy and painless removal of the article is of key importance. These articles have generally been disclosed in the inventorial register established by United States law H1602 or WO 96/33683. Some more details of these articles have been considered, for example, in the PCT application NO 95/16424. This document discloses sanitary articles having a body adhesive that is applied on the side facing the user of a sanitary napkin along the entire periphery. The problem underlying this document is mainly the secure attachment to the foot !, but also mentions the problems of disunion of these items after being used without causing undue pain to a user. The disclosure of WO 95/16424 includes a detailed analysis of the criteria for the body adhesive with respect to the watchmaking criteria. However, this document has little in regard to the problem of painless removal of these articles, since the rheological criteria taught include depilatory compositions (ie, hair removal), which are commercially available such as STREP MIEL ™ sold. in Italy by Laboratori Vaj, SpA The adhesives for topical fixation mentioned in WO 95/16424 include the current pressure sensitive adhesives used to attach sanitary napkins to previous garments, and this document only identifies the static rheological characteristics but it is reserved for the dynamic rheological behavior of a body adhesive In the international publication WO 96/13238 a model of frequency-dependent body adhesive is disclosed, however, all measurements disclosed, for example, on the page 9 were made at temperatures between -60 ° C and + 120 ° C, and at ales from 0.1 to 100 rad / sec. In order to obtain the necessary data at the application temperature (at approximately 20 ° C typical of the environment of the solution, ie storage temperatures) the equation of Williams-Landel-Ferry (hereinafter WLF). The WLF equation is empirical and only valid within certain limits, for example, it can not be used to extrapolate at temperatures below the vitreous transition temperature of the polymeric adhesive, the WLF can not be used on the bases of the values below the glass transition temperature. You can find details about the WLF equation and its • Applicability in "Principles of Polymer Processing", by Z. Tadmor and C.G.

Gogos, published by John Wiley & Sons or in "Viscoelastic properties of Polymers ", by JD Ferry also published by John Wiley &Sons, since this is now absent from WO 96/13238 the applicability of the disclosed data can not be determined.In addition, this disclosure is not related to absorbent articles provided with adaptability European patent application EP-638 303 discloses the use of a body adhesive on the side folds of sanitary napkins in order to maintain the folds in an upright position The Swiss publication CH-643730 discloses the use of a Very long sanitary napkin having beveled outer edges with a body adhesive on the four corners of the outer edges in order to provide an area for the external body adhesive of the pubic hair growth region. The formulation of the body adhesive now allows an improved direct fixation of the absorbent articles to the skin, however, these conditions It is of narrow use also cause a problem since the absorbent articles have a waterproof plastic film on its external surface. This causes perspiration and a high temperature within the article, usually described as poor ventilation, which is unacceptable to at least sensitive users of these items. This problem is substantially more pertinent for articles fixed to a user's skin than for articles attached to a garment, because these articles allow breathability through their surface facing the wearer. Based on the prior art, it is an object of the present invention to provide disposable absorbent articles for the absorption of natural liquids emanating from a user's body, which are fixed to a user's skin, allow removal No pain of the absorbent article and do not suffer from poor ventilation. It is another object of the present invention to ensure by removing the absorbent article that adhesive residues do not remain on the skin or on the user's hair. It is still another object of the present invention to provide disposable absorbent articles that are used in such close proximity to the area that the user's liquid emanates in such a way that losses of liquid to the exterior of the absorbent article are minimized or eliminated, without poor ventilation resulting from close proximity. For disposable absorbent articles used in the crotch region of a wearer, this will result in improved security against staining of skin tissue and surrounding clothing.

In addition to the above objects of the present invention, it is also desirable that sanitary napkins, pantiliners and catamenial devices reduce or even eliminate the odor emanating from the product since its application to the wearer's skin provides an odor seal, which prevents the odors of the liquid absorbed or formed from the absorbed liquid from reaching beyond the absorbent article.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to absorbent, disposable, breathable articles for topical adhesive attachment to a user of these articles.

The breathable article typically has a surface facing towards the wearer and an external surface also referred to as the garment facing surface in the context of the items worn under the clothing. The side that gives towards the garment of the normal sanitary napkins and of the sanitary napkins that use body adhesive, are generally impervious to liquid, air and water vapor. In contrast, the articles of the present invention provide breathability by being at least permeable to water vapor, since the superior effect on heat dissipation (and consequently avoiding a sticky, sweaty feeling, is achieved from the permeability to the water vapor, preferably, however, the garment-facing side of the article is also permeable to air, however, without compromising liquid impermeability, which is essential for runoff, in a particularly preferred embodiment in accordance with In the present invention, the backsheet comprises a film formed with openings, wherein the openings are funnel-shaped and have a base opening at the entrance of the funnel and a peak opening at the outlet of the funnel. is oriented on the back sheet of the breathable absorbent article, such that the peak openings are closer to the core bsorbent than the base opening. In another preferred embodiment according to the present invention, the surface that it gives to the user is provided by a breathable backsheet having at least a first and a second layer. The layers are oriented in such a way that the first layer is closer to the absorbent core than the second layer, and preferably in the first layer is a film formed with openings permeable to air, as described above, and the second layer is a film. microporous to a nonwoven substrate blown in the molten state. The breathable article comprises an absorbent core structure between the surface facing the wearer and the surface facing the garment to absorb the liquids that naturally emanate from a wearer. The breathable, disposable absorbent article according to the present invention comprises on at least part of the surface facing the wearer, an adhesive for adhesive topical attachment of the article to the wearer's skin. In a preferred embodiment, the adhesive is particularly characterized as having an elastic modulus at a temperature of 37 ° C (100 ° Fahrenheit) abbreviated G'37 and having a viscous modulus at a temperature of 37 ° C (100 ° Fahrenheit) of G "37. The adhesive is selected to have a dynamic elastic behavior such that the difference _G'37 of G'37 at a frequency of 100 rad / sec and G'37 at a frequency of 1 rad / sec not greater than 150% , preferably 80%, of G'37 at a frequency of 1 rad / sec or preferably less than 10000 Pa. The adhesive is further selected to have a dynamic viscous behavior such that the difference _G'37 of G "37 at a frequency of 100 rad / sec and G "37 at a frequency of 1 rad / sec is not greater than 10000 Pa, preferably not greater than 5000 Pa, most preferably not greater than 1000 Pa.

It is particularly preferred that the articles according to the present invention have a value of the ratio G'37 above G "37 in the total frequency range of 1 to 100 rad / sec greater than or equal to 1, preferably higher 1.6 and most preferably greater than or equal to 3.3 The value of the ratio G'37 over G "37 at least for the frequency range of 1 to 100 rad / sec may change with the increase in frequency, while not it is necessarily proportional to the change in frequency. This ratio of G'37 over G "37 should not change within the frequency range by a factor greater than 3, preferably greater than 2, and most preferably should remain constant.A 1 rad the preferred value of G'37 is below 20000 Pa, preferably is below 15000 Pa and most preferably still less than 10000 Pa. On the other hand, the value of G "37 at a frequency of 1 rad / sec should not exceed 15000 Pa, this should preferably be less than 10000 Pa and most preferably still less than 5000 Pa. The above rheological criteria can be satisfied by the adhesive compositions wherein the composition comprises from 51% to 99.5% of a plasticizer compound or the composition which is liquid at 20 ° C, from 0.5 to 20% , preferably from 5% to 15%, of a polymeric compound or polymer composition that is soluble or swellable in the plasticizer composition or composition, and with a tackifying resin in an amount of 0% to 600% by weight or of the polymeric compound. The compound or plasticizer composition is preferably selected from the group consisting of water, alcohols, preferably glycerol, glycols, polyglycols, liquid polybutenes, oils or combinations thereof, while the compound or polymer composition is preferably selected from of the group consisting of thermoplastic elastomers of block copolymers, styrene block copolymers, hydrogenated styrene block copolymers.

Very generally, the preferred body adhesive is at least partially hydrophobic, preferably 60%, more preferably 80% by weight of the adhesive consists of hydrophobic components and most preferably none of the materials in the adhesive are hydrophilic, ie, it is made entirely from hydrophobic components. In a particularly preferred embodiment with the present invention, the adhesive covers less than 20% or even more preferably less than 10% of the surface facing the wearer of the absorbent article. The present invention is more beneficially applied in the field of sanitary napkins or panty-pads.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to breathable disposable absorbent articles that are applied directly to the wearer's skin. The article exhibits absorbency for bodily fluids, protection against staining of the wearer's garments, improved physical comfort for the user, due to breathability and mode of application, and is easy to produce and pack. The breathable disposable absorbent article is described below with reference to a sanitary napkin or catamenial product, however, pantiprotectors, adult incontinence articles or sweat pads are also included under the term disposable absorbent articles. The term "sanitary napkin" as used herein, refers to an article that is worn by women adjacent to the pudendal region, and which is intended to absorb and contain the various body fluids that are discharged from the body ( example, vaginal discharge, menses and / or urine), and which is intended to be discarded after a single use. The disposable absorbent article is preferably thin, more preferably within one and 5 mm in thickness and may be, either substantially flat before use or in a pre-configured form. The terms "united" or "fixed", as used herein, encompass configurations by which a first member is directly connected to a second member and configurations by which a first member is directly connected to a second member by connecting the first member to intermediate members, which in turn they connect to the second member. In a preferred embodiment, a sanitary napkin of the present invention comprises a liquid-permeable upper sheet, a liquid-impermeable but breathable back sheet. attached to the top sheet, and an intermediate absorbent core to the top sheet and the breathable back sheet. The sanitary napkin has two main surfaces, a surface that is in contact with the body or that faces the user, and a surface that faces toward or is in contact with the garment. The upper sheet is docile, soft feeling, and non-irritating to the user's skin. The top sheet can also have elastic characteristics that allow it to be stretched in one or two directions in parts of the upper sheet or in its entire extension. In addition, the top sheet is permeable to fluid allowing fluids (eg menses and / or urine) to easily penetrate through its thickness. A suitable top sheet can be manufactured from a wide range of materials such as woven and non-woven materials; polymeric materials such as thermoplastic films formed with openings, plastic films with openings and hydroformed thermoplastic films; and thermoplastic canvases. Suitable woven and nonwoven materials may be composed of natural fibers (for example wood or cotton fibers) of synthetic fibers (for example, polymer fibers such as polyester, polypropylene or polyethylene fibers or from a combination of natural fibers and fibers). Synthetic or 2 / multicomponent fibers.

Preferred sheets for use in the present invention, are typically selected from the upper non-woven sheets with raised upper region, and the upper sheets of film formed with openings. Films formed with openings are especially preferred for the upper sheets because they are permeable to body exudates and not yet absorbent and have a reduced tendency to allow fluids to pass back through and rewet the skin of the wearer. In this way, the surface of the film that is in contact with the user remains dry, thus reducing the staining of the body and creating a more comfortable feeling for the wearer. Suitable films are described in U.S. Patent Nos. 3,929,135; patent of the States United No. 4,324,246; U.S. Patent No. 4,342,314; U.S. Patent No. 4,463,045 and U.S. Patent No. 5,006,394. Top sheets formed with particularly preferred micro apertures are disclosed in U.S. Patent No. 4,609,518 and U.S. Patent No. 4,629,643. A preferred top sheet for the present invention comprises the film formed in one or more of the above patents and which is marketed in sanitary napkins by The Procter & Gamble Company of Cincinnati, Ohio as "DRI-WEAVE". The upper sheets that do not have a homogeneous distribution of liquid passages but only a part of the upper sheet comprising passages of liquid, are also contemplated by the present invention. Typically these sheets would have the liquid passages oriented in such a way that they result in a centrally permeable upper sheet and peripherally impervious to liquids. The surface facing the wearer of the formed film topsheet can be hydrophilic to help transfer the liquid faster through the topsheet than if the body surface were not hydrophilic. In a preferred embodiment, surfactant is incorporated into the polymeric materials of the formed film topsheet as described in PCT publication WO 93/09741. Alternatively, the surface facing the body of the user of the topsheet can be made hydrophilic by treating it with a surfactant such as described in U.S. Patent No. 4,950,254. Another alternative is the so-called hybrid top sheets which incorporate structures in fibrous and film form, particularly useful embodiments of these hybrid top sheets are disclosed in PCT publications WO 93/09744; WO 93/112725 or WO 93/11726. When reference is made to the top sheet, a multilayer structure or a layer structure is contemplated. The hybrid top sheet mentioned above is a multiple layer design, but other multi-layer top sheets such as the primary and secondary top sheet designs are also considered. The absorbent structure or absorbent core may include the following components: (a) optionally a primary fluid distribution layer preferably together with an optional secondary fluid distribution layer; (b) a fluid storage layer; (c) optionally a fibrous layer ("dedusting"), which covers the storage layer; and (d) other optional components.

A Primary / Secondary Fluid Distribution layer An optional component of the absorbent structure according to the present invention is a primary fluid distribution layer and a secondary fluid distribution layer. The primary distribution layer is typically below the top sheet and is in fluid communication with it. The top sheet transfers the acquired fluid to the primary distribution layer for final distribution to the storage layer. This fluid transfer through the primary distribution layer occurs not only in the thickness, but along the longitudinal and wide directions of the absorbent product. The also optional but preferred secondary distribution layer is typically below the primary distribution layer and is in fluid communication with it. The purpose of this secondary distribution layer is to easily acquire the fluid from the primary distribution layer and transfer it rapidly to the underlying storage layer. This helps the fluid capacity of the underlying storage layer to be fully utilized. The fluid distribution layers can be comprised of any typical material for these distribution layers. In particular, the fibrous layers maintain the capillaries between the fibers even when wet, being useful as distribution layers.

B Fluid Storage Layer Positioned in fluid communication, and typically underlying the primary or secondary distribution layers, is a fluid storage layer. The fluid storage layer may comprise any normal absorbent material or combinations thereof. This preferably comprises gelling absorbent materials normally referred to as "hydrogel", "superabsorbents", "hydrocolloid" materials in combination with suitable carriers. The gelling absorbent materials are capable of absorbing large quantities of aqueous body fluids, and are also capable of retaining these absorbed fluids under moderate pressures. The gelling absorbent materials may be dispersed homogeneously or in a non-homogeneous manner within a suitable carrier. Suitable carriers, provided they are absorbent as such, can also be used alone. The gelling absorbent materials for use herein will very often comprise a polymeric gelling material, partially neutralized, lightly crosslinked, substantially insoluble in water. This material forms a hydrogel upon contact with water. These polymer materials can be prepared from polymerizable, unsaturated, acid-containing monomers, which are well known in the art. Suitable carriers include materials that are conventionally used in absorbent structures such as natural, modified or synthetic fibers, ocularly modified or unmodified cellulose fibers in the form of fluff and / or tissue. Suitable carriers can also be used together with the gelling absorbent material, however, these can also be used alone or in combinations. Very preferred are tissue and tissue laminates in the context of sanitary napkins / panty liners. One embodiment of the absorbent structure made in accordance with the present invention comprises a double layer tissue laminate formed by bending the tissue on itself. These layers can be joined together. The gelling absorbent material or other optional material may be comprised between the layers. Modified cellulose fibers such as hardened cellulose fibers can also be used. Synthetic fibers can also be used and include those made from cellulose acetate, polyvinyl fluoride, polyvinylidene chloride, acrylics (such as Orion), polyvinyl acetate, non-soluble polyvinyl alcohol, polyethylene, polypropylene, polyamides (such as nylon) , polyesters, two-component fibers, three-component fibers, mixtures thereof and the like. Preferably, the surface of the fiber are hydrophilic or are treated to be hydrophilic. The storage layer may also include filling materials, such as Perlite, diatomaceous earth, Vermiculite, etc., to improve liquid retention. If the gelling absorbent material is dispersed in a non-homogeneous manner in a carrier, the storage layer can, however, be locally homogeneous, that is, have a distribution gradient in one or more directions within the dimensions of the coating layer. storage. The inhomogeneous distribution can also refer to the laminates of carriers that partially or completely enclose the gelling absorbent materials.

C Fibrous Optional Coating ("Dusting") An optional component for inclusion within the absorbent structure according to the present invention is a fibrous layer adjacent to, and typically underlying the storage layer. This underlying fibrous layer is typically referred to as a "dedusting" layer, as it provides a substrate on which the absorbent gelling material is deposited in the storage layer during the manufacture of the absorbent structure. In fact, in those instances where the gelling absorbent material is in the form of macrostructures, such as fibers, sheets or strips, this fibrous "dedusting" layer does not need to be included. However, this "dedusting" layer provides some of the additional capabilities of fluid handling, such as rapid capillary action of the fluid along the length of the pad.

Other Optional Components of the Absorbent Structure The absorbent structure according to the present invention may include other optional components normally present in the absorbent webs. For example, a reinforcing sheet may be placed within the respective layers, or between the respective layers of the absorbent structure. These reinforcement canvases should be of such configuration so as not to form interfacial barriers for fluid transfer. Given the structural integrity that normally occurs as a result of thermal bonding, reinforcing canvases are not normally required for thermally bonded absorbent structures. Another component that can be included in the absorbent structure according to the present invention and preferably is provided near or as part of the primary or secondary fluid distribution layer, are the odor control agents. Activated carbon coated with or in addition to other odor control agents, in particular zeolite or suitable clay materials, is optionally incorporated into the absorbent structure. These components can be incorporated in any desired form, but are often included as discrete particles.

Breathable Back Blade In accordance with the present invention, the absorbent article comprises as an essential component a breathable backsheet. The main role of the breathable backsheet is to prevent the exudates absorbed and contained within the absorbent article from moistening the articles that are in contact with the absorbent article such as pajamas, and undergarments. In order to achieve this, the backsheet typically extends through the entire absorbent structure and can extend over and become part of the top sheet, bending around the absorbent structure.

Therefore, a top sheet configuration can be achieved as disclosed in U.S. Patent No. 4,342,314, column 16, lines 47 to 62, without the requirement to selectively perforate the topsheet. In addition, to prevent the transport of liquid through the backsheet, however, the breathable backsheet also allows the transfer of water vapor and preferably both water vapor and air through it, and thus allows air circulation in and out of the backsheet, and the absorbent article itself. Breathable backsheets suitable for use herein may be selected from all subsequent respirable sheets known in the art. In principle, there are two types of breathable backsheets, one-layer breathable backsheets that are breathable and impervious to liquids, and the backsheets that have at least two layers, which in combination provide both breathability and breathability. the impermeability to the liquid. The term "liquid impervious", as used herein, for breathable sheets, relates only to the barrier against loss of liquid from the article. In principle, the liquid that enters the article through the respirable back sheet are not intended to be excluded by this term. Breathable single-layer backsheets suitable for use herein include those described, for example, in British Patent No. A 2184 389, British Patent A 2184 390, British Patent 2184 391, United States Patent.

No. 4,591, 523, United States Patent No. 3,989,867, patent of the United States No. 3,156,242, and in European patent application No. 95120653.1. Double or multi-layer breathable backsheets suitable for use herein include those exemplified in U.S. Patent No. 3,881,489, U.S. Patent No. 4,341, 216, U.S. Pat.

No. 4,713,068, United States Patent No. 4,818,600, European Patent No. 203 821, European patent 710,471, European patent 710 472, and in European patent applications 95120647.3, 95120652.3, 95120653.1 and 96830097.0. Particularly preferred are the backsheets that meet the requirements as defined in European Patent Application No. 96830343.8 and more preferably wherein the absorbent article, in general, also meets the requirements as described therein. According to the present invention, the breathable backsheet comprises at least one, preferably, at least two layers permeable to water vapor. Suitable water vapor permeable layers, two-dimensional, flat, micro and macroporous films, monolithic films, macroscopically expanded films and films formed with openings. In accordance with the present invention, the openings in the layer can be of any configuration, but are preferably spherical or oblong. The openings can also be of variable dimensions. In a preferred embodiment, the openings are preferably evenly distributed across the entire surface of the layer, however, the layers having only certain surface regions punctured are also contemplated. The two-dimensional flat films as used herein have openings that have an average diameter of 5 micrometers to 200 micrometers. Typically, microporous, two-dimensional flat films suitable for use herein have openings having average diameters of 150 micrometers to 5 micrometers, preferably 120 micrometers to 10 micrometers, most preferably 90 micrometers to 15 micrometers. Typical two-dimensional flat macroporous films have openings having average diameters of 200 micrometers to 90 micrometers. Macroscopically expanded films and films formed with openings (three-dimensional films), suitable for use herein, typically have openings having diameters of 100 micrometers to 500 micrometers. The embodiments according to the present invention wherein the back sheet i comprises a macroscopically expanded film or a film formed with openings, the back sheet will typically have an open area greater than 5%, preferably from 10% to 35% of the total surface area of the back sheet. Suitable two-dimensional flat layers of the backsheet can be made of any material known in the art, but are preferably manufactured from commonly available polymeric materials. Suitable materials are, for example, GORE-TEX®, or Sympatex® type materials well known in the art for their application in so-called breathable garments. Other suitable materials include XMP-1001, from Minnesota Mining and Manufacturing Company, Saint Paul, Minnesota, E.U.A. As used herein, the term "two-dimensional flat layer" refers to the layers having a depth of less than 1 mm, preferably less than 0.5 mm, wherein the openings have a uniform average diameter along their length, and which do not they protrude from the plane of the layer. Materials with openings for use as a backsheet in the present invention can be produced using any of the methods known in the art, such as described in European Patent 293,482 and the references herein. In addition, the dimensions of the openings produced by this method can be increased by applying a force across the plane of the backsheet layer (i.e., mono- or biaxial stretching of the layer). Films formed with suitable apertures include films having discrete apertures, which extend beyond the horizontal plane of the garment facing surface toward the core, thus forming protuberances (three-dimensional films). The protuberances have a hole located at their terminal ends. Preferably, said protuberances are of a funnel shape, similar to those described in U.S. Patent No. 3,929,135.

The openings located within the plane and the holes located at the terminal end of the protuberances themselves, can be circular or non-circular, provided that the dimension or cross-sectional area of the hole at the termination of the protrusion is smaller than the dimension or area of cross section of the opening located within the surface facing the garment of the layer. Preferably, these films formed with openings are unidirectional such that they have substantially at least, if not completely, a directional liquid transport capacity in a direction towards the core. Macroscopically expanded films suitable for use herein include the films as described, for example, in U.S. Patent No. 4,637,819 and U.S. Patent No. 4,591,523. Suitable monolithic films include HytreL, available from DuPont Corporation, USA, and other materials as described in index 93 Congress, Session 7A "Adding Value to Nonwovens", JC Cardinal and T. Trouilhet, DuPont de Nemours International, SA, Switzerland. In accordance with the present invention, the backsheet may comprise, in addition to the water vapor permeable layer, additional backsheet layers. Additional layers may be located on either side of said water vapor permeable layer of the backsheet. The additional layers may be of any material, such as fibrous nonwoven layers, particularly hydrophobic fibers and preferably meltblown fibers, or additional water vapor permeable layers as described hereinbefore while maintaining the basic breathability of the article. , and preferably improve the liquid transport resistance of the backsheet.

Adhesive for topical fixation Articles according to the present invention, as stated above, are applied directly to the wearer's skin. In particular, sanitary napkins are applied in the genital region of a typically female user, around the liquid discharge area. The word "skin" according to the present invention is not only related to the specific dermis of the user, but includes the mucosal tissue as well as the hair typically found in the genital region of the users, for example, of the sanitary towels. In order to provide the fixing of the lateral folds according to the present invention to the wearer's skin, it is necessary to provide a certain area on the side of the upper sheet of the article which is facing towards the wearer, with an adhesive for topical fixation also referred to as body adhesive. Various designs are contemplated in this respect, but preferably the body adhesive is provided, along the peripheral edge of the top sheet such that a central area of the article is left without adhesive. This will more appropriately facilitate the positioning of the article such that the upper sheet permeable to the liquid without adhesive on it, is placed adjacent to the orifice that emanates the body fluid, in such a way that the liquid that emanates is immediately transported towards the absorbent structure of the body. absorbent article without the possibility of leaks or spills. However, it is not necessary that the body adhesive be provided in a closed circle around the edge of the top sheet, but that it can be provided in incremental areas such as discrete points or lines in such a way as to disengage between the different places. of fixation providing additional comfort to the user of these items. In order to meet the objectives according to the present invention, the following should be considered.

Physical, Physical, and Adhesive Characteristics of a Topical Adhesive Even when topical adhesives similar to pressure sensitive adhesives are used on the hair of human skin and mucous tissuesIt is understood that topical adhesive compositions can only with difficulty be considered typical pressure sensitive adhesives (referred to as PSA hereinafter) on the basis of the most characteristic rheological behaviors that these materials identify. In fact, as the person skilled in the art of adhesives knows, the most characteristic aspect that distinguishes a PSA from other substances that can temporarily stick things (as can, for example, water), is the fact that its rheological and especially the elastic modulus G 'varies greatly with the frequency of the applied stresses. More particularly the G 'of the PSA may increase over some types of magnitude while the frequency of the applied voltages varies from the typical binding frequency to the typical disbudding frequency, i.e. from 1 rad / sec to 100 rad / sec as is indicated below. As a first consequence, it is inferred that it is inadmissible to define materials intended to be used as "adhesives", giving values of the rheological parameters and especially of G 'to a fixed frequency value. This can be misleading because in the absence of other features it will include materials that do not have practical values. It is believed by consequence that the rheological characterization should be based on dynamic considerations. This applies not only to the elastic modulus G 'but also to the viscous module G "and consequently also for (d) = G7G 'It is well known that the typical PSA does not only have a high variation of G' across the considered frequencies, but also there is a variation of G" even higher than can be to be close to or even to be higher than the value of G ', ie (d) becomes approximately or even higher than 1, particularly at the frequencies that are typical of disunity. Without wishing to be bound by theory, this can be interpreted as meaning that a high fraction of the energy applied for disunity dissipates in internal fractions (so that it is not effective in causing disunity), while this fact causes macroscopically the registration of a very high level of adhesive force. In order to provide good bonding conditions, ie at a frequency of about 1 rad / sec, the absolute values of the elastic modulus should not be too high, otherwise the adhesive is too hard and is not capable of binding or molding intimately to the surface to which it is expected to adhere.

It is also important to have an absolute value of G "low in order to have good cohesion, which is particularly valuable for a direct application on the human body, while the material remains soft and able to adhere gently to the skin. The person skilled in the art will also recognize that the Transition Temperature Vitrea Tg of the PSA is a parameter that is useful to more fully define the group of useful PSA materials. As indicated above, the materials useful as body adhesives according to the present invention have rheological characteristics which are measured at a reference temperature of 37 ° C, such as body temperature, and within a frequency range. It has been found that when applying an article with a body adhesive, the adhesive contact is formed at a low frequency, while the disunion occurs at the speed of removal of the article. This speed is expressed as a frequency of 100 rad / sec while it has been found that the low frequency of forming the adhesive bond is in the order of 1 rad / sec. Therefore, the range of frequencies to be used according to the present invention is between 1 and 100 rad / sec. The following set of characteristics must be satisfied: in the frequency range, the percentage variation of the elastic modulus G'37 is less than or equal to 150%, preferably less than 100% and more preferably less than 80%, of G'37 at 1 rad / sec, preferably the variation is less than 10000 Pa in absolute terms. This is satisfied by the body adhesive exemplified below, while, for example, Promeon RG-63B, cited in the prior art, shows in the same frequency range a variation of G'37 of 331%, which is not acceptable according to the present invention. in the frequency range the variation of the viscous modulus G ", - PC is greater than 10000 Pa, preferably not greater than 5000 Pa, most preferably not greater than 1000 Pa. the value of the proportion G'37 / G" 37 al less for the frequency range of 1 rad / sec to 100 rad / sec should preferably be the unit or higher, more preferably 1.6 or higher and most preferably 3.3 or higher, while not exceeding about 50. It should be noted that G 'and G "at the application frequency of 1 rad / sec at 100 rad / sec are taken at a temperature of 37 ° C. In the practical use of the articles according to the present invention, the actual storage temperature of the article and by As a result, the temperature of the body adhesive when applied varies widely, for example, storage in a hot bath near a radiator can reach up to approximately 37 ° C, while storage in a storage room or bathroom without heating but with a window open during the winter it can be close to 0 ° C. Nevertheless, since the article in accordance with the present invention is used directly on the skin and the user typically would not like to be applied to an article too cold, the actual temperature of the body adhesive will reach 37 ° C very quickly or even be heated by the user before the application. Consequently, it is believed that the characteristics of the adhesive bond are selected in a manner very appropriate to body temperature. As indicated above, the rheological behavior can also be related to the values of the Transition Temperature Vitrea Tg. For body adhesives according to the present invention, the Tg should preferably be less than -15 ° C, more preferably less than -20 ° C and most preferably less than -25 ° C.

Chemical Characteristics and Composition of a Topical Adhesive In order to meet the requirements of the above rheological and physical characteristics of a body adhesive, the following formulation criteria can be used. It should be noted that most of the compositions useful as the body adhesive have a substantially gel-like structure and are preferably gels. This derives from the fact that: the predominant component is a liquid material at room temperature. A macromolecular or polymer component is present in minor amounts against the plasticizer. This form, in the preferred modalities, a three-dimensional network made by the physical and chemical bonds between the molecules. Particularly useful physical links are the bonds present in systems containing block thermoplastic elastomers. More specifically, the compositions comprise: from 0.5 to 20%, preferably from 5% to 15%, by weight of a macromolecular polymer substance or a mixture of these substances soluble or capable of swelling in the aforementioned plasticizer (s). As non-limiting examples, these polymeric or macromolecular substances can be natural and / or synthetic, such as natural gums or derivatives such as natural gums and gelatins, their derivatives and alginates; polyacrylics; polyvinyl alcohol; polyethylene oxide; polyvinylpyrrolidone (PVP) or polyvinyl ethers, their copolymers and derivatives; cellulose derivatives; Thermoplastic elastomers of Block Copolymer and preferably Styrenic Block Copolymers and more preferably the hydrogenated grades Styrene / Ethylene-Butylene / Styrene (SEBS), / Styrene / Isoprene / Styrene (SIS), and Styrene / Ethylene-Propylene / Styrene (SEPS). from 51 to 99.5% by weight of a plasticizing substance or a mixture of plasticizing substances, which are liquid at room temperature. As non-limiting examples, the plasticizer may be water, various alcohols (such as in particular glycerol), glycols, polyglycols, liquid polybutenes, natural or synthetic oils such as vegetable oils, mineral oils, or combinations thereof. from 0 to 600% by weight of a macromolecular polymeric substance of a tackifier resin whose main scope is to form the Tg especially in systems based on synthetic polymers. from 0 to 10% and more preferably from 0 to 5% by weight of a substance to facilitate and stabilize the gelation of both the hydrophobic and hydrophilic liquid plasticizers. These can be for oil systems, for example, C8 to C22 fatty acids, their metal salts and their polyoxyl derivatives; lanolin derivatives, silica; bentonite, montmorillonite and its derivatives; polyamides, waxes or mixtures thereof. Common additives known in the art as preservatives, antioxidants, anti-ultraviolet agents, pigments, mineral fillers, rheology modifiers, etc., may also be comprised in amounts of up to 10% each.

When chemical lattices are formed in the system, a crosslinking agent may be present in amounts of up to 5% by weight. Chemical crosslinking can also be formed by the mutual neutralization of polymers having different functionalities as in the reaction between polyacrylic acids and polysaccharides. Typical compositions for body adhesives can be divided into three families according to the nature of their main component, i.e., normally the plasticizer or liquid plasticizers (s): 1) The hydrophobic compositions in which the plasticizer is typically a oil or mixtures of oils of vegetative origin! and the mineral and the polymer is normally a synthetic polymer, preferably an elastomer, soluble or capable of swelling in the oil or in the oils. 2) Mixed phase compositions in which both hydrophobic and hydrophilic components, possibly in both the plasticizers and the polymers, form two or more separate phases. In these cases, an emulsifier / surfactant is preferably present at a suitable level to form stable emulsions between the incompatible phases. For body adhesives according to the present invention, it is preferable that the hydrophobic components are predominant against the hydrophilic components. 3) The hydrophilic compositions in which typically the plasticizer is water / glycerol / glycols and the like and / or mixtures thereof and the polymer phase is of synthetic (for example polyacrylics), or natural (for example natural gums) or mixtures thereof. It is important that, unlike what is already known in the medical field and the prior art cited, hydrophilic compositions are not preferred, although hydrophobic and mixed phase compositions 1) and 2) are preferred in the applications of the present invention. This partly depends on technical reasons in the sense that many of the hydrophilic compositions used in the medical field show elasticity and cohesion too low to be useful in the present application. The other reason for preferring hydrophobic or easily mixed compositions is that the application of the present invention, particularly in the field of sanitary napkins, will include a likelihood of contacting the body adhesive with the liquid being absorbed. Since the liquids are all of a general aqueous type, in contact with a hydrophilic body adhesive, it would result in a certain absorption of the body fluids in the body adhesives. This would then have the result of changing the rheological characteristics, and therefore the functionality of the body adhesive, causing an unhygienic appearance but also causing the body fluids to remain in direct contact with the skin for a prolonged period, which is not typically desired by none of the disposable absorbent articles according to the present invention. In addition, this may also constitute a potential disadvantage for the user, since some of the hydrophilic compositions are potentially good growth media for the growth of many microorganisms, including still pathogens. In addition, the hydrophilic body adhesive also tends to be perceived as cold and damp when the application of a sanitary pad or sweat pad of the new armpit is not in line with the typical expectation of the consumer. Additional problems result from the fact that in particular body adhesives comprising water as the plasticizer, they have a tendency to dry unless sealed within an impermeable package.

The absorbent articles according to the present invention can be made by any of the ordinary manners in the art. The application of the adhesive to the side of the top sheet of the absorbent article should not cause greater problems for those skilled in the art, since it can be provided by similar techniques as are commonly used for a panty fastener device for sanitary napkins. The total area of the surface facing the user of the absorbent article that is covered by the body adhesive should not be greater than 20%, preferably not greater than 10%. Preferably, the adhesive is encircling the periphery of the absorbent article and in the case of the upper sheets of film (or when the backsheet is folded over the upper sheet) the adhesive is preferably on a part of the film, which is not permeable to liquids. The body adhesive on the item (as is common with panty bras), needs to be protected before use. This protection can be provided by a release liner such as a paper treated with silicone or surfactant, provided that this paper is a good release surface for the particularly selected body adhesive. In principle, the absorbent article according to the present invention is held in the user by the body adhesive and does not require additional supports to remain in place. However, it is possible to provide, for example, a sanitary napkin with a slip-resistant coating on the side of the backsheet in order to prevent the sanitary napkin from gradually migrating out of position. Even when the panty fastener adhesives are not desired and consequently are not preferred according to the present invention, they are not strictly speaking, excluded in the context of the present invention.

EXAMPLE 1 An oil-based composition useful in the present invention was mixed using 9.9% by weight of Krato G-1651. A block copolymer Styrene / Ethylene / Butylene / Styrene containing 33% by weight of styrene and available from Shell Co., and 59.3% by weight of Kaydol, a paraffinic mineral oil available from Witco Co. Furthermore the composition contains 301 parts of the tackifying resin for 100 parts of the Kraton polymer. The tackifying modifier resin was Escorez 5300, a hydrogenated resin available from Exxon Co. Magnesium stearate, available, was added from Cario Erba S.P.A. a cogelling people for the oil at a level of 0.7% by weight. Iranox 1010 was added an antioxidant available from Ciba-Geigy, at a level of 0.3% by weight. Finally, the formulation had the following percentage composition: Kraton G-1651 9.9% by weight Kaydol 59.3% by weight Esocrez 5300 29.8% by weight Magnesium stearate 0.7% by weight Irganox 1010 0.3% by weight The composition showed the following rheological properties at 37 ° C. a) Elastic modulus at 1 rad / sec, G'37 = 6876 Pa b) Proportion between Elastic and Viscous Modules at 1 rad7sec G'37 / G "37 = 12.49 Proportion between Elastic and Viscous Modules at 100 rad / sec, G, 37 / G "37 = 7.01 c) The ratio of G'37 to 100 rad / sec on G'37 at 1 rad / sec was 1,308. The above formulation was judged as comfortable for application on the hairy, sensitive skin.

COMPARATIVE EXAMPLE A Composition oil-based composition was mixed using 7.1% by weight of Kraton G-1651, a styrene / ethylene-butylene / styrene block copolymer containing 33% by weight of styrene and available from Shell Co. , and 49.9% by weight of Kaydol, a paraffinic mineral oil available from Witco Co. Moreover, the composition contained 704 parts of tackifier resin per 100 parts of the Kraton polymer. The tackifying modifier resin was Regalrez 3102, a hydrocarbon resin available from Hercules Co. The Magnesium Stearate available from Cario Erba S.p.A. It was used as a cogelling agent for the oil at a level of 0.7% by weight. Irganox 1010 added, an antioxidant agent available from Ciga-Geigy, at a level of 0.3% by weight. Finally, the formulation had the following percentage composition: Krato G-1651 7.1% by weight Kaydol 41.9% by weight Regalrez 3102 50.0% by weight Magensium stearate 0.7% by weight Irganox 1010 0.3% by weight The composition showed the following rheological properties at 37 ° C. a) Elastic modulus at 1 rad7sec G'37 = 3059 Pa b) Proportion between elastic and viscous moduli at 1 rad / sec G / G '= 2.53 Proportion between the visocose elastic moduli at 100 rad / sec, G'37 / G "37 = 0.74 c) The G'37 ratio at 100 rad / sec on G'37 at 1 rad / sec was 4.944 The above formulation was judged to be highly uncomfortable for application to the forearm skin. sensitive was unacceptable.

Claims (10)

1. A disposable, breathable, absorbent article for topical adhesive attachment to a user of said article, the article having a surface facing the wearer and a surface facing the garment and comprising an absorbent core between the surface facing the user and the surface facing the garment, characterized in that the surface facing the garment of said article provides breathability to the article because it is at least permeable to vapor; the article comprises on at least part of the surface that towards the user a topical adhesive fixing adhesive of the article, said adhesive having an elastic modulus at the temperature of 37 ° C (100 ° F), G'37 and having a module viscous at a temperature of 37 ° C (100 ° F), G "37, said adhesive being selected to have a dynamic elastic behavior in such a way that the difference, _G'37, of G'37 at a frequency of 1 rad / sec and G "37 at a frequency of 100 rad / sec is not greater than 150% of G'37 at a frequency of 1 rad / sec, preferably not greater than 10000 Pa, and the adhesive selected to have a dynamic viscous behavior of such so that the difference _G "37, of G" 37 at a frequency of 1 rad / sec, and G "37 at a frequency of 100 rad7sec is not greater than 10000 Pa, preferably not greater than 5000 Pa.

2. The absorbent article Breathable according to claim 1, wherein G'37 is less than 20,000 Pa, preferably less than 15,000 Pa, most preferably less than 10,000 Pa, at a frequency of 1 rad / sec.

The breathable absorbent article according to any of the preceding claims, wherein G'37 is less than 20,000 Pa, preferably less than 15,000 Pa, most preferably less than 10,000 Pa, at a frequency of 1 rad / sec.

The breathable absorbent article according to any of the preceding claims, wherein the adhesive is a composition of materials comprising from 51% to 99.5% by weight a plasticizer compound or composition which is liquid at 20% C; 0.5% to 20% by weight of a compound or polymer composition that is soluble or swellable in the plasticizer composition or composition; a tackifying resin in an amount of 0% to 600% by weight of the compound or the polymer composition.

The breathable absorbent article according to claim 6, wherein said plasticizer compound or composition is selected from the following group: water, alcohols, glycols, oil or combinations thereof; and said polymeric compound or composition is selected from the following group: block copolymer thermoplastic elements, styrene block copolymers, and hydrogenated styrene block copolymers.

The breathable absorbent article according to any of the preceding claims, wherein 80% by weight of the adhesive consists of hydrophobic components and most preferably all of the adhesive components are hydrophobic.

The breathable absorbent article according to any of the preceding claims, wherein the adhesive covers less than 20%, preferably less than 10%, of said surface facing the wearer.

8. The breathable absorbent article according to any of the preceding claims, wherein the surface facing the wearer is provided by a back sheet permeable to air, the back sheet comprising a formed film with openings, preferably the openings are funnel-shaped having a base opening at the entrance of the funnel and a peak opening at the exit of the funnel, the apertured formed film being oriented in such a manner that the peak openings are closer to the core than the base openings.

9. The breathable absorbent article according to any of the preceding claims, wherein the surface facing the user is provided by a breathable back sheet comprising: minus a first layer and a second layersaid rear sheet oriented in such a way that the first layer is closer to the core than the second layer, preferably the first layer is a film formed with openings permeable to air, and most preferably the second layer is a microporous film or a non-transparent substrate. blown fabric in the molten state.

10. The breathable absorbent article according to any of the preceding claims, which is a sanitary napkin or a pantyhose.