MXPA99005941A - Disposable absorbent article with side cuffs comprising an adhesive for secure topical attachment of the side cuffs to the skin of a wearer - Google Patents

Abstract

The present invention relates to disposable absorbent articles, particularly sanitary napkins, pantiliners, adult incontinence products which have side cuffs, or baby diapers. In particular the present invention relates to such disposable absorbent articles with side cuffs which are maintained in their in-use position by direct attachment to the skin of the wearer. The topical adhesive attachment of such side cuffs 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 WITH SIDE DOUBLES THAT UNDERSTAND AN ADHESIVE FOR THE SAFETY TOPICAL FIXATION OF SIDE DOUBLES 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 baby diapers, which have lateral folds. In particular, the present invention relates to these disposable absorbent articles with lateral folds that are held in their position of use by the direct attachment or binding to the wearer's skin. The adhesive topical fixation of the lateral folds needs to be safe and adequate when applied and during the use of these articles, not to cause even discomfort when removing the article. This is achieved by the present invention by selecting the Theological characteristics of the adhesives of the lateral folds of these articles.

BACKGROUND OF THE INVENTION The general 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 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 of a person are the subject of the present invention. The folds of these articles are applied to the skin of a wearer in a region where a considerable amount of hair grows in such a way that the criterion of easy and painless removal of the article is of key importance. Articles for direct attachment to the skin have generally been disclosed in the inventor's 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 that have 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 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 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 fix sanitary napkins to prior garments., this document only identifies the static rheological characteristics but is reserved as regards 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 reported, for example, on page 9 were made at temperatures between -60 ° C and + 120 ° C, and at real frequencies of 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 Williams-Landel-Ferry equation (hereinafter WLF) was used. 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. 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 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, Furthermore, neither this document nor WO 95/16424 disclose absorbent articles that have lateral folds, but only relates to items directly attached to the skin.

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. However, this document does not disclose any of the details about the particular adhesive useful in this context. 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 liquids naturally emanating from a user's body, which have lateral folds and whose lateral folds are securely attached to the skin of a user at the time of application and during use. However, these lateral folds adhered to the body also need to allow painless removal. It is another object of the present invention to ensure upon removal of the absorbent article that residual adhesive will not remain on the skin or on the wearer's hair. It is another object of the present invention that the adhesive for topical attachment of the side bends does not cause a cold or otherwise unacceptable temperature sensation upon application, despite the difference in adhesive temperature with respect to skin temperature. . It is another object of the present invention to provide disposable absorbent articles that are used in close proximity to the area emanating from the user's liquid, that liquid losses to the exterior of the absorbent article be reduced or minimized. 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 garments.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to disposable absorbent articles comprising lateral folds which have a region of contact with the user, designed. The article typically has a surface facing towards the wearer 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 naturally from a user. The disposable absorbent article according to the present invention comprises about a! less part of the region designated for contact with the user of the lateral folds is an adhesive for topical adhesive attachment of the lateral fold to the wearer's skin. The detailed analysis of the sequence of common situations that occur from the application of these disposable absorbent articles with lateral folds until the moment of the removal of this article, has shown the specific characteristics of the adhesive needed to be satisfied in order to achieve the desired performance objectives. 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 capacity of the adhesive to attach quickly and adhere safely. The 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 absorbent articles with lateral folds, which satisfy 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 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. 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 comprise a topical adhesive that 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'37 (100 rad / sec) -G "37 (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 either • the ratio of? C37 / G37 (1 rad / sec) is not greater than 1.5, preferably not greater than unity and most preferably not greater of 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 ratio G'37 / G "37 at least for the frequency scale of about 1 rad / sec to 100 rad / sec, preferably it should be 2 or more, more preferably 3.3 or higher, while not exceeding about 50, preferably 30, anywhere in the frequency range • the rheological behavior may also be related to the glass transition temperature Tg values. For the topical adhesives according to the present invention, it should preferably be lower -15 ° C, more preferably less than -20 ° C, and most preferably less than -25 ° C • the rheological performance and acceptance of a disposable article comprising a topical adhesive may also be related to the heat capacity Preferably, the specific heat capacity of the topical adhesive is less than 4 J / g / K, more preferably less than 3 J / g / K and most preferably less than 2 J / g / K. 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 conductivity of the specific heat is as low as possible, preferably between 1 and 0.1 W / m / K, more preferably between 0.6 and 0.1 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. Also the criteria of hygienic appearance and comfortable feeling when in contact are important, such that adhesive compositions are preferred which will be transparent or white, 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.

In a particularly preferred embodiment with the present invention, the adhesive covers the entire region designated for contact with the user of the lateral folds. The present invention can also be applied if the side bends are elasticized.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to disposable absorbent articles having side folds. The article exhibits absorbency for bodily fluids, protection against staining of the wearer's garments, improved physical comfort for the user and whose article 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 baby diapers 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 "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 to 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 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 (for example menses and / or urine), 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 No. 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 the 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. The topsheet typically extends throughout the entire absorbent structure and to the outside of the coextensive area with the absorbent structure. The top sheet can extend and form part or all of the preferred side flaps, the side wrapping elements or the wings. 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 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, slightly 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. 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. The back sheet mainly prevents the exudates absorbed and contained in the absorbent structure from wetting 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 structure and can extend over and become part of the top sheet by folding around the absorbent structure. 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 approximately 0.051 mm. Exemplary polyethylene films are manufactured by Clopay Corporation of Cincinnati, Ohio, under the designation P18-1401 and by Ethyl Corporation, Visque in a 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 respirability 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. In addition, the absorbent articles according to the present invention comprise lateral folds. The term "lateral bends" refers to articles that have barrier means which are capable of extending away from the surface facing the user of the article. These are located near the periphery portions of an absorbent article, in particular, near the longitudinal sides of the article. The lateral folds are well known in the art and are widely used in diapers and sanitary napkins. These can be formed integrally with and separated from the article. For example, in articles having a topsheet, the topsheet may have an extension or fold on the longitudinal sides of the article that is capable of extending from the surface facing the user towards the user. The function of the barrier of the lateral folds to improve the leakage is indisputable when considering the numerous variations of the lateral fold executions described in the art and commercially used in sanitary napkins or towels. The lateral folds can be impermeable, impervious to liquid, but breathable, hydrophobic, hydrophilic, but treated to be hydrophobic or hydrophilic. However, it is also well known that the function of the lateral bending barrier depends strongly on how well-maintained they are in their designed use position. The position of use of the barrier folds is typically such that they extend away from the surface facing the user of the article towards the user and are maintained in such a way that they touch the user. However, keeping them in this position during the period of total use has proven difficult. For example, U.S. Patent No. 3,860,003 discloses elasticized disposable absorbent articles, wherein an elastic member is placed on the side flap of the top sheet product and the back sheet so as to form a can-like configuration that the side flaps form a barrier along the edges of the product. U.S. Patent No. 4,738,677 shows two types of barrier folds. A set of barrier folds extending in a longitudinal direction of the article while the waist folds are also provided by extending in the lateral direction at the front and rear end of the article and overlapping with the other barrier folds. Therefore, a bag is formed by the four overlapping folds. The present invention is more suitably applied to the lateral barrier bends in the longitudinal direction while, of course, the application of the lateral barrier bends is also possible. More recently in the international publication WO 94/02095, extensible absorbent articles having extensible barriers that are also susceptible to the benefits of the present invention are disclosed. The lateral folds in the disposable diapers are also called barrier folds and are well known. Barrier bends have been described, in for example, U.S. Patent No. 3,776,233, U.S. Patent No. 4,695,278; U.S. Patent No. 4,704,115; U.S. Patent No. 4,738,677; U.S. Patent No. 4,795,454, U.S. Patent No. 4,808,177; U.S. Patent No. 4,808: 178; U.S. Patent No. 4,816,025; U.S. Patent No. 4,900,317, U.S. Patent No. 4,938,755; U.S. Patent No. 5,021,051, U.S. Patent No. 5,032,120, U.S. Patent No. 5,085,654, European Patent No. EP-A-3,774,640 or EP-A-459,178. Care must be taken that the side bends / barrier folds are not confused with the leg folds in the diapers. The leg cuffs are normally used to wrap the leg of a user of a diaper, while the lateral cuffs are extending from the surface facing the user towards the user, typically to be in contact with the wearer's skin. The inventors are not aware that attempts have been made in diapers to provide a body adhesive to the lateral folds. This may be partly due to the fact that the diapers are fixed to the user and consequently remain better in place, than, for example, the sanitary napkins, which are attached to an undergarment of the wearer. A first attempt to provide sanitary napkins in particular with self-adhesive side bends is shown in European patent EP-638 303. However, this publication does not disclose which type of adhesives for topical applications are possibly useful, and therefore speaks very highly. generally about body adhesives. This general disclosure leaves the particular requirements for the top-fixing adhesive of the lateral folds undefined. The present invention addresses the problem of providing a good bonding and painless detachment of the topical application of the lateral folds in order to keep the lateral folds in their position of use, which are connecting the lateral folds to a user's skin. . The lateral folds according to the present invention can be activated (i.e., elevated above the surface facing the user), by various means. For example, these can be elasticized as is very common in the art. The lateral folds can be provided in such a way that the lateral folds elevate when placing the article towards an arched shape (as is generally the outline of cross section in the genital region of a user, which would separate a user into left and right halves). ). Given the particular benefit of the present invention, it is also possible to have side bends that are only activated by the body adhesive. In fact, in this preferred design, the lateral folds do not rise above the surface facing the body towards the wearer before applying the article to the wearer. When the article is applied, for example, a sanitary towel to an undergarment (usually by means of a panty fastening adhesive), and then the garment is pulled upwards), the article is placed in close proximity to the wearer and touches the wearer's genital area. In this position, the surfaces designated to be in contact with the user of the lateral folds touch the wearer and since they are provided with a body adhesive these will adhere to the wearer. Then on the additional use of the article, the narrow contact initially achieved when the undergarment is pulled up is released to some extent, while the lateral bends remain in their adhered position and thus provide their desired barrier benefit. By pulling down on the undergarment, the panty fastening adhesive is strong enough to delaminate the body adhesive on the lateral folds of the wearer's skin and allow the lateral folds to again squeeze onto the surface facing the user of the sanitary napkin. It is understood that for the person skilled in the art the various known lateral bending designs will require the adaptation of the dosage and amount of body adhesive area that is applied to the lateral bends. However, these design criteria will be selected by those skilled in the art without major effort and would only require in individual cases simple essays of the article with real users to refine the design of the article.

Adhesive for topical fixation of the lateral folds The lateral folds of lining according to the present invention are fixed directly to the wearer's skin. 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 that is typically found in the genital region of the users of the sanitary napkins. In order to provide the fixation of the lateral folds according to the present invention to the skin of the wearer, it is necessary to provide a certain region of the lateral folds designed for contact with the user of the article, 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 outermost edge of the side folds. This will more appropriately facilitate the lifting of the lateral bends upwards and keeping them in this position. In this way, body fluids are prevented from running out of the article on the sides and being transported towards 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 continuous line on the lateral fold, but that it can be provided in incremental areas such as discrete points or lines in such a way as to uncouple between the different attachment locations providing comfort additional to the user of these articles. 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 in the hair of human skin and in the mucosal tissues, it is understood that body adhesive compositions can only with difficulty be considered as typical pressure sensitive adhesives ( referred to as PSA in the following) 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 and especially the elastic modulus G 'varies greatly with the frequency of the applied stresses. More particularly the G 'of the PSA can increase over some types of magnitude while the frequency of the applied voltages varies from the typical frequency of union to the typical frequency of disunion, that is, from 1 rad / sec to 100 rad / sec as indicated below. As a first consequence, it is inferred that it is inadmissible to define materials intended 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 believed by consequence that the rheological characterization should be based on dynamic considerations. This not only applies to the elastic modulus G 'but also to the viscous modulus G "and consequently also to (d) = G'VG' 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 ', ie (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 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. 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 by applying a lateral fold 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 according to the present invention is between 1 and 100 rad / sec. Furthermore, 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 consequently the temperature of the body adhesive when applied varies widely.For example, the storage in a hot bath near a radiator can reach up to approximately 37 ° C, while the storage in a room of storage or bath without heating but with a window open during the winter can be close to 0 ° C. However, since the article according to the present invention is used directly on the skin and the person skilled in the art is aimed at selecting an adhesive composition having a small specific heat capacity (eg, preferably less than 4 J / g / K, more preferably less than 3 J / g / K, most preferably men or that 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 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. of G'37 (1 rad / sec) on G "37 (1 rad / sec) is important to ensure that these two values are balanced upon 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 the secure fixation of the lateral fold to a user during the period of total 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 / eg) - G'X (100 rad / sec) G'37 (1 rad / sec) -G "3 (1 rad / sec) it needs to be old enough to ensure that the dynamic behavior of both the elastic modulus and the viscous modulus are maintained in a relationship that provides secure adhesion during use and painless and easy removal at the end of the period of use. Finally, the person skilled in the art 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 topical adhesives tools. The following set of characteristics must be satisfied: • 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 from 2 to 50, preferably from 3 to 30. * 1st rate 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 • any of the proportion of? C37 / G37 (1 rad / sec) is not greater than 1.5, preferably not greater that the unit 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 scale of frequency of about 1 rad / sec to 100 rad / sec, 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 the 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 article comprising a topical adhesive may also be related to the specific heat capacity. Preferably, the specific heat capacity of the topical adhesive is less than 4 J / g / K, more preferably less than 3 J / g / K and most preferably less than 2 J / g / K.

• 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 conductivity of the specific heat is as low as possible, preferably between 1 and 0.1 W / m / K, more preferably between 0.6 and 0.1 W / m / K.

Chemical and Compositional Characteristics 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 the macromolecular polymer 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; poiiamides, 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. The chemical crosslinking can also be formed by the mutual neutralization of the polymers having different functionalities as in the reaction between the polyacrylic acids and the polysaccharides. The compositions for the 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 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 plasticizers and polymers, form two or more separate phases. In these cases, an emulsifier / surfactant is preferably present at an adequate level to form stable emulsions between incompatible phases. For the 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, in a manner different from what is already known in the medical field and from 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, would result in a certain absorption of body fluids in 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 upon application of a sanitary napkin or a new sweat pad, which 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 lateral folds 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. The body adhesive on the side folds of 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.

Alternatively, especially for diapers, this protection can be achieved by folding the article on itself, preferably, however, in such a way that the adhesive on the lateral folds has not been folded on itself. In principle, the absorbent article according to the present invention is held in the user by the usual means applicable to the article, such as the adhesive panty clips and / or the wings for the sanitary napkins and the side closures with adhesive or mechanical tapes for diapers. In a particular preferred embodiment, sanitary napkins or panty liners have wings, side wrapping elements or side flaps that are formed by comprising parts of the backsheet and the topsheet extending beyond the side of the absorbent core and being they join together outside the absorbent core, for example, as disclosed in EP-A-130 848 or EP-A-134 086. It is also possible to provide, for example, a sanitary napkin only with a slip-resistant coating on the side of the back sheet in order to prevent the sanitary towel from gradually migrating out of position, while the body adhesive over the side bends provides additional support for the sanitary napkin to remain in place.

EXAMPLE 1 An oil-based composition useful in sanitary napkins according to the present invention was prepared using 9.9% by weight of Krato G-1651, a styrene / ethylene / butylene / styrene block copolymer containing 33% by weight of styrene and which is available from Shell Co., and 59.3% by weight of Kaydol, a paraffinic mineral oil available from Witco Co. The composition further 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 agent 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 rad7sec G'37 / G" 37 = 12.49 d) Proportion of G 'HOO rad / seq) - GX (100 rad / seq) G'3 (1 rad / sec) - G "37 (1 rad / eg) = 1.22 e) The proportion of? G '37 over G'37 (1 rad / sec) was 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 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, 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 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 rad7sec G'37 = 3059 Pa b) Viscose module at 1 rad7sec G "37 1208 = Pa c) Proportion between elastic and viscous modulus at 1 rad / sec G'37 / G" 37 = 2.53 d ) Proportion of G 'dOO rad / sec) - GX (100 rad / sec) G'37 (1 rad / sec) - G "37 (1 rad / eg) = - 2.87 e) The proportion of? G'37 over G'37 (1 rad / sec) was 3.944 with? G'37 = 12064.7 Pa.

The above formulation was judged to be highly uncomfortable for application on the 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. surface facing the garment, said article further comprising lateral folds having a region designed to be in contact with the user characterized in that the article comprises on at least part of the region designated for contact with the body of said lateral folds an adhesive said adhesive having an elastic modulus at a temperature of 37 ° C (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) is in the scale from 100 Pa to 15,000 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 G'37 ratio (100 rad / sec -G '(100 rad / seq) 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, 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 1 to 100 rad / sec is in the range of 2 to 50, preferably 3.3 to 30. The disposable absorbent article according to any of the preceding claims, wherein said 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 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 composition 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 elastomers, styrene block copolymers and hydrogenated styrene block copolymers, polyacrylics, polyvinyl alcohol, natural gum or gelatins, polyethylene oxides, polyvinylpyrrolidone, polyvinyl ethers , cellulose derivatives, or combinations thereof. 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 said adhesive has a glass transition temperature of less than -15 ° C, preferably less than -20 ° C, most preferably -25 ° C. 7. A topical adhesive according to any of the preceding claims, wherein said adhesive has a specific heat capacity of less than 4 J / g / K, more preferably less than 3 J / g / K and most preferably less than 2 J / gK. 8. The disposable absorbent article according to any of the preceding claims, wherein said adhesive has a specific heat conductivity of less than 1 W / m / K, preferably in the scale of 1 and 0.1 W / m / K, more preferably in the scale of 0.6 and 0.1 W / m / K. 9. The article according to any of the preceding claims, wherein said adhesive covers the entire region designated for contact with the user of the lateral bends. 10. The article according to any of the preceding claims, wherein the side bends are elasticized.