MXPA99005943A - Disposable absorbent article for secure topical adhesive attachment to the skin of a wearer - Google Patents

Abstract

The present invention relates to disposable absorbent articles particularly sanitary napkings, pantiliners, adult incontinence products or sweat pads. In particular the present invention relates to such disposable absorbent articles which are worn by direct attachment to the skin of the wearer in the area where absorption of bodily liquids is desired. The topical adhesive attachment of such articles needs to be secure and pleasing upon application and during use of such articles, yet cause no discomfort upon removal of the article. This is achieved by the present invention selecting the rheological characteristics of adhesives for such articles.

Description

ABSORBENT ARTICLE DISPOSABLE FOR TOPICAL FIXATION ADHESIVE TO THE SKIN OF A USER FIELD OF THE INVENTION The present invention relates to disposable absorbent articles, particularly sanitary napkins, pantiliners, adult incontinence products or sweat pads. In particular, the present invention relates to these disposable absorbent articles which are used by fixing them directly to the wearer's skin in the area where the absorption of body fluids is desired. The adhesive topical fixation of these articles needs to be safe and proper when applied and during the use of these items, still not causing discomfort when removing the article. This is achieved by the present invention, by selecting the rheological characteristics of the adhesives for these articles.

BACKGROUND OF THE INVENTION The general prior art in the field of disposable absorbent articles for topical application to a user's skin was developed particularly in the field of relief bandages, plasters and bandages. However, these articles are typically applied in an emergency situation, where, for example, a wound has occurred on the wearer's skin and absorption of body fluids emanating from the wound is desired. In this context, aspects of the performance of the absorbent article such as the use and easy application and easy removal without pain, discretion is subordinated to criteria such as sterility, healing protection, mechanical protection of the wound. Also the absorbent articles that protect the wound are mainly adhered to the areas of the skin where the body hair can be removed before the application of the article or where little or no hair grows. The present invention is not related to absorbent articles that protect wounds but are related to absorbent articles for the absorption of body fluids which naturally emanate from a body without a wound. For example, sanitary pads or pantiliners for use in the genital region are these items. Also the incontinence devices that are used, for example, in the genital region or the sweat pads that are used in the region of a person's armpit are the subject matter 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 skin, but it also mentions the problems of disunion of these articles after being used without causing undue pain to a user. The disclosure of the international publication WO 95/16424 includes a detailed analysis of the criteria for the body adhesive with respect to the rheological criteria. However, this document has little respect for the problem of painless removal of these articles since the rheological criteria taught include depilatory compositions, that is, for the removal of the hair, which are commercially available as STREP MIELE ™ sold in Italy by Laboratori Vaj SpA The adhesives for topical fixation mentioned in WO 95/16424 also include the current pressure sensitive adhesives which are used to attach sanitary napkins to undergarments. further, this document only identifies the static rheological characteristics but is reserved as regards the dynamic rheological behavior of a body adhesive. In WO 96/13238 a frequency model of the body-dependent adhesive is disclosed. However, all measurements reported, for example, on page 9 were made at temperatures between less than 60 ° C and 120 ° C and the actual frequency is 0.1 to 100 rad / s. In order to obtain the necessary data at the application temperature (at approximately 20 ° C, typical bath, ie storage temperature) the Williams-Landel-Ferry equation (hereinafter WLF) was used. This WLF equation is empirical and only valid within certain limits, for example, it can not be used to extrapolate temperatures below the glass transition temperature of a polymeric adhesive, also the WLF can not be used on the basis of values obtained below the glass transition temperature. Details about the WLF equation and its applicability in "Principles of Polymer Processing" can be found by Z. Tadmor and C.G. Gogos, published by John Wiley & amp;; Sons or in "Viscoelastic Properties of Polymers", by J.D. Ferry also published by John Wiley & They are. Since this is missing from WO 96/13238 the applicability of the disclosed data can not be achieved. 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 a vertical 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 outer body adhesive of the region of the pubic hair growth. 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 the body of a user, which are securely attached to a user's skin at the time of delivery. application and during use. However, these articles adhered to the body also need to provide painless removal of the absorbent article. It is another object of the present invention to ensure upon removal of the absorbent article that no adhesive residue will remain on the user's skin or hair. It is another object of the present invention that topical fixation does not cause a cold or otherwise unacceptable temperature sensation upon application without considering a difference in the temperature of the adhesive with respect to the temperature of the skin. It is another object of the present invention to provide disposable absorbent articles that are used in such close proximity to the area emanating from the user's liquid, that losses of liquid to the exterior of the absorbent article are minimized or eliminated.

For the disposable absorbent articles used in the crotch region of the wearer this will result in improved security against staining of the skin tissue and surrounding clothing. Furthermore, of 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 skin of the user provides an odor seal which prevents the odors of the liquid absorbed or those formed from the absorbed liquid from reaching beyond the absorbent article.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to disposable absorbent articles for topical adhesive attachment to a user of these articles. The article typically has a surface facing the user and an external surface, also called a surface facing the garment in the context of articles worn under clothing. The article comprises an absorbent core structure between the surface facing the user and the surface facing the garment to absorb the liquids emanating from a wearer. The disposable absorbent article according to the present invention comprises on at least part of the surface that gives the user an adhesive for the adhesive topical attachment of the article to the wearer's skin. The detailed analysis of the sequence of common situations that occur from the application of these disposable absorbent articles until the moment of removal of this article, has shown the very specific characteristics of the adhesive needed to be met in order to achieve the objectives desired performance, in particular, secure fixation when applied, secure fixation during use and removal at the end without pain. The characteristics that have been considered in this context are the elastic modulus that describes the elastic behavior of the material, and the viscous modulus that describes the viscous behavior of the adhesive material. The viscous behavior of the adhesive can be interpreted to represent an indication of the adhesive's ability to quickly bond and adhere safely. He Elastic behavior can be interpreted as a sign or signal of the "firmness" behavior of the adhesive. Its value is also critical for good initial fixation. It is believed that their combination is an indicator of the force required when the removal occurs. The relationship between the elastic modulus and the viscous modulus is considered to be an indication over which the fraction of the removal energy within the adhesive will be dissipated and over which the fraction is available to cause actual removal. In order to provide disposable absorbent articles that meet the requirements of initial secure fixation, secure fixation during use and easy / painless removal, the relationship between the elastic modulus and the viscous module as well as its dynamic behavior is of key importance. The body adhesive has an elastic modulus at a temperature of 37 ° C (100 ° Fahrenheit), abbreviated G'37 and a viscous modulus at a temperature of 37 ° C (100 ° Fahrenheit) of G "37. an elastic dynamic behavior defined as? G'37 which is the difference of G'37 at a frequency of 100 fad7sec and G "37 at a frequency of 1 rad / sec and a viscous dynamic behavior? g" 37 that the difference of G'37 at a frequency of 100 rad / sec and 6"37 at a frequency of 1 rad / sec. The articles according to the present invention have a body adhesive which satisfies the following conditions. "G'37 (1 rad / sec) is on the scale from 1500 Pa to 20000 Pa, preferably 1500 Pa to 15000 Pa, more preferably 3000 Pa to 10000 Pa. • G" 37 (1 rad / sec) is on the scale from 100 Pa to 15000 Pa, preferably 100 Pa to 10000 Pa, more preferably 3000 Pa to 5000 Pa. • The proportion of G'37 (1 rad7sec) / G "37 (1 rad7sec) is on the scale of 2 to 50, preferably from 3 to 30. • the ratio G '(100 rad / sec) -G "(100 rad / sec) G'37 (1 rad / sec) - G" 37 (1 rad / sec) is not less than 0.5, preferably on the scale of 0.7 to 3, most preferably on the scale of 1 to 1.8 • any of the proportion of? G'37 / (337 (1 rad / sec) is not greater than 1.5, preferably not greater than unity and most preferably not greater than 0.8, or "G'37 is not greater than 10000 Pa, preferably less than 5000 Pa, more preferably less than 2000 Pa, or both • the value of the G'37 / G ratio" 37 at least for the frequency scale from about 1 rad / sec to 100 rad / sec, it should preferably be 2 or higher, more preferably 3.3 or higher, while not exceeding about 50, preferably 30, anywhere in the frequency range. • the rheological behavior can also be related to the values of the vitreous transition temperature Tg. For topical adhesives according to the present invention, it should preferably be less than 15 ° C, more preferably less than 20 ° C, and most preferably less than -25 ° C. • The behavior and rheological acceptance of a disposable item that includes a topical adhesive can also be related to the specific heat capacity. Preferably, the specific heat capacity of the body adhesive is less than 4 J / gK, more preferably less than 3 J / gK and most preferably less than 2 J / gK. • The behavior and rheological acceptance of a disposable absorbent article comprising a body adhesive may also be related to the specific heat conductivity of the adhesive. Preferably, the specific heat conductivity is greater than 0.1 W / m / K, more preferably greater than 0.6 W / m / K and most preferably greater than 1 W / m / K.

Provided that the above rheological conditions are satisfied, the adhesives will also satisfy conditions such as sufficient adhesion (to avoid adhesive residue on the skin), which are critical to the commercial use of these adhesives and apparent to those skilled in the art. Adhesive compositions that meet the above criteria can be used as topical adhesives for disposable absorbent articles as long as they also meet the common requirements of being safe to use on human skin or animals during use and generally after disposal. Article. Often the criteria of hygienic appearance and comfortable feeling when in contact are important, such that adhesive compositions that will be transparent or white are preferred, and which avoid an uncomfortable, cold feeling when applied. The above rheological criteria and other considerations can be satisfied by the adhesive compositions, wherein the composition comprises from 51% to 99.5% of a plasticizing compound or composition, which is liquid at 20 ° C, from 0.5 to 20%, preferably 5% to 15% of a polymeric compound or composition that is soluble or capable of swelling in the plasticizer composition or composition and with a tackifying resin in an amount in the range of 0% to 600% by weight of the polymeric compound . The plasticizing compound or composition is preferably selected from the group consisting of water, alcohols (preferably glycerol), glycols, polyglycols, liquid polybutenes, oil or combinations thereof. The polymeric compound or composition is preferably selected from the group consisting of block copolymer thermoplastic elastomers, styrene block copolymers and hydrogenated styrene block copolymers.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to 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 wearer, and is easy to produce and pack. The 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 re use or in a pre-configured form. The terms "attached" 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, who in turn 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 back sheet attached to the upper sheet, and an intermediate absorbent core to the upper sheet and the 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 top 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). Synthetics 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. especially preferred for the upper sheets because they are permeable to body exudates and not yet absorbent and have a reduced tendency to allow the fluids to pass back through and rewet the user's skin.Thus, the surface of the film that is in contact with the user remains dry, thus reducing the spotting of the body and creating a more comfortable feeling for the user. Suitable films are described in U.S. Patent Nos. 3,929,135; U.S. Patent 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 transfer of fluid 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 can 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 of 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. 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.

D 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. Preferred control systems for use herein include the following combinations: i) silica, AGM and zeolites, preferably in a ratio of 5: 1: 1 to 1: 1: 5 :, most preferably 3: 1: 1: a 1: 1: 3; ii) zeolite, activated carbon, and AGM: iii) silica and AGM preferably in a ratio of 5: 1 to 1: 5, more preferably 3: 1 to 1: 3; V) zeolites and AGM; v) silica and zeolites, preferably in a ratio of 1: 5 to 5: 1 more preferably 1: 3 to 3: 1, vi) chelating agents, particularly ethylenediamine tetraacetate; and vii) chelating agents in combination with any of the odor control systems i) av), preferably in a ratio of 1: 10 to 10: 1, more preferably 1: 5 to 5: 1, most preferably 1: 3 to 3: 1. According to the present invention, the amount of odor control system incorporated in the absorbent article, can be easily determined by the person skilled in the art, and is also dependent on the intended use of the absorbent article, taking into consideration the dimensions of the article. absorbent. Typically, the absorbent article comprises from 5 grams per square meter to 400 grams per square meter, more preferably from 10 grams per square meter to 300 grams per square meter, most preferably from 150 grams per square meter to 250 grams per square meter, basis weight of said odor control system. For example, a sanitary napkin or a panty protector may comprise from 0.25 grams to 5 grams, preferably from 0.4 grams to 3 grams, most preferably from 0.5 grams to 2.5 grams of said odor control system. The backsheet mainly prevents the exudates absorbed and contained in the absorbent core from moistening the articles that are in contact with the absorbent product., such as underpants, briefs, pajamas and undergarments. The backsheet is preferably impervious to liquids (eg, urine and / or menses), 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 readily conform to the contour and general shape of the human body. The back sheet can also have elastic characteristics that allow it to stretch in one or two directions. The backsheet typically extends through the entire absorbent core and can extend over and become part of the top sheet by bending around the absorbent core. Thus, a configuration of the top sheet as disclosed in U.S. Patent No. 4,342,314, column 16, lines 47 to 62 can be achieved without the requirement to selectively perforate the top sheet. The backsheet may 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 is a 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 Ethyl Corporation, Visquean Division of Terre Haute, Indiana, under the designation XP-39385. The backsheet is preferably embossed and / or finished without gloss to provide a more fabric-like appearance. Preferably, the backsheet also provides breathability to the absorbent article by being at least permeable to water vapor, preferably permeable to air, however, without compromising the main function of the backsheet. The backsheet can be a laminated material, for example, of a combination of microporous film, nonwoven material and / or film formed with openings. The breathability, if desired, can be limited to the periphery of the backsheet or this can be through the entire back sheet. 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, breathable, single-layer backsheets that are breathable and impervious to liquids, and backsheets that have at least two layers, which in combination provide both breathability and breathability. impermeability to 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 backsheets of a single layer 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, U.S. Patent No. 3,989,867, U.S. Patent 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. Patent No. 4,713,068, U.S. Patent No. 4,818,600, European Patent No. 203 821, European Patent 710,471, European Patent 710 472, and 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.

Adhesive for Topical Fixation The articles according to the present invention, as said before, are applied directly to the user'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 to the absorbent structure of the 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 may 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, Rheological and Adhesive Characteristics of a Body Adhesive Even when body adhesives similar to pressure sensitive adhesives are used on human skin hair and mucosal tissues, it is understood that body adhesive compositions may it is only with difficulty that they are considered to be typical pressure sensitive adhesives (referred to as PSA hereinafter) on the basis of the most characteristic rheological behaviors that identify these materials. 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 parameters 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 inadmissible to define materials destined to be used as "body 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 consequently necessary that the rheological characterization should be based on dynamic considerations. This applies not only to the elastic modulus G 'but also to the viscous modulus G "and consequently also to (d) = G7G' It is well known that the typical PSA does not have only a high variation of G 'through the frequencies considered, but there is also a variation of G "even higher that may be close to or even higher than the value of G ', that is (d) becomes approximately or even higher than 1, particularly in 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 disunion dissipates within the adhesive (so that it is not effective at causing disunion), while this fact causes macroscopically the registration of a very high level of adhesive force. 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 as the body temperature and within a frequency scale. It has been found that by applying an article such as a sanitary napkin with a body adhesive, adhesive contact is formed at a low frequency, while disbonding occurs at the rate of removal of the article. This speed is expressed as a frequency of 100 rad / sec whereas 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 in agreement is between 1 and 100 rad / sec. Furthermore, it should be noted that G 'and G "at the application frequency of 1 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 consequently 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 However, since the article in accordance with the present invention is used directly on the skin and the person skilled in the art is directed to select the composition of the adhesive, the warming but with a window open during the winter can be close to 0 ° C. so that it has a small specific heat capacity (for example, preferably less than 4 J / g / K, most preferably less than 2 J / g / K) the actual temperature of the body adhesive will reach 37 ° C very quickly or even be heated by the user before application. Consequently, it is believed that the characteristics of the adhesive bond are selected in a manner very appropriate to body temperature. 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 able to bond intimately or molding 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 a good cohesion that is particularly valuable to be used in the field of sanitary napkins, and to generate when articles are used that are frequently removed and adhered again or replaced, While the material remains soft, and is able to adhere gently to the skin, the ratio of G'37 (1 rad / sec) to G "37 (1 rad / sec) is important to ensure that these two values are balanced when occurring the application of the disposable absorbent article to the skin. At the same time, the absolute changes of G'37 need to be limited within the range of frequencies considered. Consequently, a low value must be maintained for the ratio of? G'37 (ie, G'37 (100 rad / sec) -G'37 (1 rad / sec)), above G'37 ( 1 rad7sec) in order to maintain secure attachment of the disposable absorbent article to a user over the entire period of use without causing discomfort during this period or in the removal / delamination of the article. This can also be expressed in absolute terms by keeping the? G'37 below certain values. Importantly, the ratio of G '^ (100 rad / sec) - G'X (100 rad / sec) G'37 (1 rad / sec) -G "37 (1 rad / sec) need to be sufficiently large to ensure that the dynamic behavior of both the elastic modulus and viscous modulus is maintained in a relationship that provides secure adhesion during use and painless and easy removal at the end of the period of use. The technique will also recognize that the vitreous transition temperature Tg of the adhesive composition, the specific heat capacity, and the specific heat conductivity are parameters that are useful to more fully define the group of useful topical adhesives. of following characteristics: • G'37 (1 rad / sec) is on the scale from 1500 Pa to 20000 Pa, preferably 1500 Pa to 15000 Pa, more preferably 3000 Pa to 10000 Pa. • G "37 (1 rad / sec) is on the scale of 100 Pa to 15000 Pa preferred 100 Pa to 10000 Pa, more preferably 3000 Pa to 5000 Pa. • the proportion of G'37 (1 rad7sec) / G "37 (1 rad7sec) is on the scale of 2 to 50, preferably 3 to 30. • the GX ratio (100 rad / secVG '(100 rad / sec) G'37 (1 rad / sec) - G "37 (1 rad / sec) is not less than 0.5, preferably on the scale from 0.7 to 3, very preferably on the scale of 1 to 1.8 • any of the ratio of? C37 / G37 (1 rad / sec) is not greater than 1.5, preferably not greater than unity and most preferably not greater than 0.8, or? G'37 not is greater than 10000 Pa, preferably less than 5000 Pa, more preferably less than 2000 Pa, or both. • the value of the ratio G'37 / G5"37 at least for the frequency scale of about 1 rad / sec to 100 rad / sec, should preferably be 2 or higher, most preferably 3.3 or higher, while not exceeding about 50, preferably 30, anywhere in the frequency range. • the rheological behavior can also be related to the values of the vitreous transition temperature Tg. For body adhesives according to the present invention, it should preferably be less than -15 ° C, more preferably less than 20 ° C, and most preferably less than -25 ° C. "The behavior and rheological acceptance of a disposable absorbent article comprising a body adhesive may also be related to the specific heat capacity. Preferably, the specific heat capacity of the body adhesive is less than 4 J / gK, more preferably less than 3 J / gK and most preferably less than 2 J / gK. • The behavior and rheological acceptance of a disposable absorbent article comprising a topical adhesive may also be related to the specific heat conductivity of the adhesive. Preferably, the specific heat conductivity is greater than 0.1 W / m / K, more preferably greater than 0.6 W / m / K and most preferably greater than 1 W / m / K.

Chemical Characteristics and Composition of a Body Adhesive In order to provide body adhesive compositions that meet the requirements of the rheological and physical characteristics of a body adhesive above, the following formulation criteria should 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 the plasticizer, which is a liquid material at room temperature a macromolecular or polymeric 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 typically 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 / lsoprene / 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 polymer substance of a tackifier resin whose main scope is to form the Tg especially in systems based on synthetic polymers. from O 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 C4 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 such 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. The resulting compositions for the body adhesives can be divided into three families according to the nature of their main component, i.e., the plasticizer or liquid plasticizers (s): 1) The hydrophobic compositions in which the plasticizer is typically an oil or mixtures of oils of vegetable and mineral origin and the polymer is usually a synthetic polymer, preferably an elastomer, soluble, or capable of swelling the oil or oils. 2) Mixed phase compositions in which both hydrophobic and hydrophilic components, possibly 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 topical 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 from the prior art cited, hydrolytic 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 so as to prevent the sanitary napkin from gradually migrating out of position. Also 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 er! the context of the present invention.

EXAMPLE 1 An oil-based composition useful in sanitary napkins was prepared according to the present invention, using 9.9% by weight of Krato G-1651. A styrene / ethylene / butylene / styrene block copolymer 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. Further the composition contains 301 parts of the tackifier resin per 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 Module at 1 rad / sec, G'37 = 6876 Pa b) Viscous Module at 1 rad / sec, G'37 = 550.5 Pa c) Proportion between Elastic and Viscous Modules at 1 rad7seg G'37 / G " 37 = 12.49 d) The ratio G (100 rad / sec) -G ". (100 rad / sec) G'37 (1 rad / sec) - G "37 (1 rad / sec) = 1.22 e) The proportion of G'37 at 100 rad / sec on G'37 at 1 rad / sec was of 0.308, with? G'37 = 2124 Pa The above formulation was judged as comfortable for application on the hairy, sensitive skin.

COMPARATIVE EXAMPLE A composition based on compound oil 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 41.9% 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 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, an antioxidant agent available from Ciga-Geigy, was added 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 rad / sec G'37 = 3059 Pa b) Viscous module at 1 rad / sec G "37 = 1208 Pa c) Proportion between elastic and viscous moduli at 1 rad / sec G'37 / G" 37 = 2.53 d) The ratio G '^ (100 rad / secVG "^ (100 rad / sec) G'37 (1 rad / sec) - G" 37 (1 rad / sec) = - 2.87 e) The proportion of G'37 at 100 rad / sec on G'37 at 1 rad / sec was 3,944, with? G'37 = 12064.7 Pa The above formulation was judged to be highly uncomfortable for application to forearm skin. The application to sensitive hairy skin was unacceptable.

Claims (10)

1. A disposable absorbent article for topical adhesive attachment to a user of said article, the article having a surface facing the wearer and a garment facing surface and comprising an absorbent core between the surface facing the wearer and the wearer. a surface facing the garment, characterized in that the article comprises on at least part of the surface facing the user a topical adhesive fixing adhesive of the article, said adhesive having an elastic modulus at the temperature of 37CC (100 ° F), G'37 and having a viscous modulus at a temperature of 37 ° C (100 ° F), G "37, said adhesive being selected to have G'37 (1 rad / sec) on the scale from 1500 Pa to 20000 Pa, preferably 1500 Pa to 15000 Pa, more preferably 3000 Pa to 10000 Pa; - G "37 (1 rad / sec) on the scale from 100 Pa to 15000 Pa, preferably 100 Pa to 10000 Pa, more preferably 3000 Pa to 5000 Pa; the proportion of G'37 (1 rad7sec) / G "37 (1 rad7sec) is on the scale of 2 to 50, preferably 3 to 30; the ratio GX (100 rad / sec) -G "(100 rad / sec) G'37 (1 rad / sec) - G" 37 (1 rad / sec) is not less than 0.5, preferably on the scale of 0.7 to 3, most preferably on the scale of 1 to 1.8; or alternatively, either, G'37 (100 rad / sec) - G'37 (1 rad / sec) is not greater than 10000 Pa, preferably less than 5000 Pa, preferably less than 2000 Pa; or the ratio G'37 (100 rad / sec) - G'37 (1 rad / sec) / G'37 (1 rad / sec) is not greater than 1.5, preferably not greater than 1, most preferably not greater than 0.8 , or a combination thereof.

2. The article according to claim 1, wherein the value of the ratio G'37 over G "37 in the frequency range from 1 to 100 rad / sec is in the range from 2 to 50, preferably from 3.3 to 30. The disposable 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 of 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 tackifier resin in an amount of 0% to 600% by weight of the compound or polymer composition. 4. The absorbent article according to claim 3, wherein said plasticizer compound or composition is selected from the following group: water, alcohols, glycols, oil or combinations thereof; The polymer composition or composition is selected from the following group: block copolymer thermoplastic elements, styrene block copolymers, and hydrogenated styrene block copolymers. The disposable 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 disposable absorbent article according to any of the preceding claims, wherein the adhesive has a glass transition temperature less than -15 ° C, preferably less than -20 ° C, most preferably less than -25 ° C. The disposable absorbent article according to any of the preceding claims, wherein the adhesive has a specific heat capacity of less than 4 J / g / K, preferably less than 3 J / g / K, most preferably less than 2 J / g / K. The disposable absorbent article according to any of the preceding claims, wherein said adhesive has a specific heat conductivity greater than 0.1 W / m / K, preferably greater than 0.6 W / m / K, most preferably greater than 1 W / m / K. The disposable 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 user. 10. The disposable absorbent article according to any of the preceding claims, which is a sanitary napkin or a pantyhose.