MXPA99005947A - Adhesif for secure topical attachment to the skin and comfortable removal - Google Patents

Abstract

The present invention relates to topical adhesives for attachment to the skin. In particular the present invention relates to such topical adhesives which can be employed for attachment to the skin in the area where absorption of bodily liquids is desired. The topical adhesive provides secure attachment and is pleasing to the skin upon application, yet causes no discomfort and a low level of adhesive residues on the skin upon removal. This is achieved by selecting the chemical composition and rheological characteristics of the topical adhesives, in particular with reference to the relationship between the elastic modulus G'and the viscous modulus G''of the topical adhesive.

Description

ADHESIVE FOR TOPIC FIXATION SAFE TO THE SKIN AND PROPER REMOVAL FIELD OF THE INVENTION The present invention relates to topical adhesives for fixing to the skin. In particular, the present invention relates to these topical adhesives which can be used for fixing to the skin in the area where the absorption of body fluids is desired, particularly for the adhesion of sanitary napkins, pantiliners, adult incontinence products. or pads for oozing. The topical adhesive provides secure fixation and is suitable for application on the skin, yet does not cause discomfort and has low level of adhesive residue on the skin when removed. This is achieved by selecting the chemical composition and the characteristics of the topical adhesives, in particular with reference to the relationship between the elastic modulus G 'and the viscous modulus G "of the topical adhesive.

BACKGROUND OF THE INVENTION The general prior art in the field of topical adhesives for fixation to the 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 are subordinated to criteria such as sterility, healing protection, mechanical protection of the wound. Also the articles Absorbents 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 relates to topical adhesives that are particularly useful for absorbent articles for the absorption of body fluids, which naturally emanate from the body without a wound. For example, to fix sanitary pads or pantiliners in the genitourinary region. Also, devices that are used, for example, in the genital region or the sweat pads that are used within the region of a person's armpit, can suitably employ the adhesive of the present invention. These topical adhesives have generally been disclosed in the inventorial register established by United States law H1602 or WO 96/33683. Some additional details of the adhesive have been disclosed in PCT publication WO 95/16424. In this document sanitary napkins having a topical adhesive that is applied on the side facing the user of a sanitary napkin along the entire periphery is disclosed. The problem underlying this document is mainly the secure attachment to the skin but it also mentions the problems of disunion of these items 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 topical 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 that are used to attach sanitary napkins to undergarments. In addition, this document only identifies the static rheological characteristics but is reserved for the dynamic rheological behavior of a topical adhesive. In WO 96/13238 a frequency model of the topical dependent adhesive is disclosed. Nevertheless, 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 topical adhesive on the side folds of sanitary napkins, in order to keep the folds in an upright position. The Swiss publication discloses the use of a very long sanitary napkin having beveled outer edges with a topical adhesive on the four corners of the extreme edges in order to provide an area of external topical adhesive of the pubic hair growth region. Both requests are reserved as regards the adhesive composition.

Based on the prior art, it is an object of the present invention to provide a topical adhesive for secure fixation and painless removal of the skin, combined with a reduced amount of residual adhesive remaining on the skin or on the hair after removing the composition of the topical adhesive. It is still a further object of the present invention that the adhesive for topical fixation does not cause a cold or otherwise unacceptable temperature sensation upon application occurrence despite a temperature difference of the adhesive with respect to the temperature of the skin. In addition to the above objects of the present invention, it is also desirable that topical adhesives provide adhesives additional benefits such as supplies / dispersion of a compound or composition that is beneficial to the skin or to the general body. In addition, topical adhesives that do not affect the natural condition of the skin, for example, which are respirable or water vapor transmitters or water vapor / sweat absorbers, are preferred.

BRIEF DESCRIPTION OF THE INVENTION The present invention will be explained in its use in disposable absorbent articles for adhesive topical attachment to a user of these articles. The article typically has a surface that faces towards the body or the user and an external surface. The article comprises an absorbent core structure between the surface facing the user and the external surface to absorb the fluids emanating from a user, such as urine, feces, menstruation, sweat and vaginal discharge. The topical adhesive allows to fix an article to the skin of the user. The detailed analysis of the sequence of common situations that occur from the application of these disposable absorbent articles until the moment of the Removal of this article, has shown the specific characteristics of the adhesive needed to be met in order to achieve the desired performance objectives, in particular, the initial secure fixation, the secure fixation during use, the final removal without pain and a level Reduced adhesive residue on the skin after removal. 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. 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. The relationship between the elastic and viscous modulus also gives a signal or indication of the internal cohesiveness of the adhesive, which is in turn related to the possible presence of adhesive residues on the skin after removing the topical adhesive composition. In order to provide topical adhesives for initial and prolonged secure fixation and easy / painless removal, the relationship between the elastic modulus and the viscous modulus as well as its dynamic behavior is of key importance. The topical 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. The difference? G'37-G "37) between the elastic modulus G'37 at a frequency of 1 rad / sec and the viscous modulus G" 37 at a frequency of 1 rad / sec also is defined by the topical adhesive. This difference gives an indication of the behavior of the topical adhesive with respect to the level of adhesive residue left on the skin after removing the topical adhesive. The adhesive also has 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 topical adhesive according to the present invention 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 in the range of 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 3 to 30. • the proportion 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 ratio of ? G'37 / 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 is not greater than 10000 Pa, preferably lower than 5000 Pa, more preferably less than 2000 Pa, or both. • the difference ? (G'37-G "37) (1 rad / sec) is greater than or equal to 1250 Pa, preferably greater than or equal to 2500 Pa, more preferably greater than or equal to 3500 Pa. In addition, the preferred conditions are: • the value of the ratio G'37 / G "37 at least for the frequency scale of about 1 rad / sec to 100 rad / sec, should preferably be 3.3 or higher, more preferably 5 higher, more preferably 10 or higher, while not exceeding about 30, preferably 20, 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 topical adhesive can also be related to the specific heat capacity. Preferably, the specific heat capacity of the topical 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 topical adhesive can 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. 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 of the 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 compositions of the adhesive, wherein the composition comprises of 45%, preferably from 51% to 99.5% of a plasticizing compound or composition, which is liquid at 20 ° C, from 0.5 to 20%, preferably from 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 50% by weight of the composition, preferably from 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, polyacrylics, polyvinyl alcohol, natural gum or gelatins, polyethylene oxide, polyvinylpyrrolidone (PVP ), polyvinyl ethers, cellulose derivatives, or combinations thereof.

DETAILED DESCRIPTION OF THE INVENTION Adhesive for Topical Fixation The topical adhesive according to the present invention is applied directly to the skin. In a particular application, the adhesive can be used in sanitary napkins which 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 also as the hair that is typically found in the genital region of the users of the sanitary napkins. In order to provide fixation of an article according to the present invention to the skin, it is necessary to provide a certain area on the side of the item that is facing the skin with the topical adhesive. For the various designs of sanitary napkins it is contemplated, but preferably the topical adhesive is provided adjacent to the peripheral edge of the topsheet such that a central area of the article is left without adhesive. This will more appropriately facilitate the placement of the towel in such a way that the region of the liquid-permeable upper sheet is placed adjacent to the hole where the body fluid emanates, such that the liquid emanating is transported immediately towards the absorbent structure of the absorbent article without the possibility of leakage or spillage. The topical adhesive is provided with the preferred pattern on the surface facing the article user, in a layer having a thickness or caliper that is preferably constant. The layer may preferably be continuous or alternately discontinuous, for example, in the form of dots, spirals or strips.

Physical, Physical, Adhesive, and Adhesive Characteristics of a Topical Adhesive Even when topical adhesives similar to pressure-sensitive adhesives are used on human skin and mucosal tissues, it is understood that topical adhesive compositions can only with difficulty be considered typical pressure sensitive adhesives (referred to as PSA hereinafter) on the basis of rheological behaviors, more characteristic 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 between two glass plates), is the fact that its rheological parameters and especially the elastic modulus G 'vary 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 "topical adhesives", giving values of the rheological parameters and especially of G 'at 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 record of a level of adhesive strength very elevated As indicated above, the materials useful as topical adhesives according to the present invention, have rheological characteristics that are measured at a reference temperature of 37 ° C (as the normal body temperature of humans), and within a scale of frequencies. It has been found that upon application of an article such as a sanitary napkin, such as a topical 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. It is believed that the characteristics of the adhesive bond are selected most appropriately at the temperature of the human body. Since the topical adhesive according to 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 to have a small specific heat capacity (eg, preferably less than 4 J / g / K), the actual temperature of the topical adhesive will reach 37 ° C very quickly or will still be heated by a human before application. 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 for use in the field of sanitary napkins, and generate when articles are used that are frequently removed and adhered to. new or replaced, as long as the material remains soft, and able to adhere gently to the skin. The proportion of G'37 (1 rad / sec) over G "37 (1 rad / sec) is important to ensure that these two values are balanced upon adhesion to the skin.At the same time, the absolute changes of G ' 37 need to be limited within the range of frequencies considered.As a consequence, 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 topical adhesive without causing discomfort during the time or in the removal / delamination.This can also be expressed in absolute terms maintaining the? G'37 down certain values.

Importantly, the ratio of G'- (100 rad / eg) - G "- ^ (100 rad / sec) G'37 (1 rad / sec) - G" 37 (1 rad / sec) needs to be sufficiently higher to ensure that the dynamic behavior of both the elastic modulus and the viscous modulus are maintained in a relationship that provides safe adhesion and painless and easy removal. Further, when the removal phase of a topical adhesive composition is particularly considered, for the attachment to the skin of a user of the disposable absorbent articles, it is commonly recognized that good removal conditions of the topical adhesive are achieved when the adhesive can be removed. easily removed from the skin and hairs that typically grow on the skin where the disposable absorbent article is in contact with the wearer's body, without causing pain to the wearer, therefore not sticking too firm upon removal to the skin and hairs of the user, particularly, as is apparent to those skilled in the art, a good removal also means that the topical adhesive does not leave residues that remain on the skin or on the hairs. The difference? (G'37- (3"37) between the elastic modulus G'37 (1 rad / sec), and the viscous modulus G" 37 (1 rad / sec) of the topical adhesive of the present invention is relevant for the scope of providing a reduced level of adhesive residue on the user's skin after removing the topical adhesive This difference in fact gives an indication of the behavior of the topical adhesive of the present invention, while referring to the level of the adhesive. adhesive residues on the skin after removing the topical adhesive from the user's skin Without being bound by any theory, the difference between the elastic modulus G 'and the viscous modulus G "is a direct measurement of the internal cohesion of the adhesive. topical adhesive Therefore, increasing the difference? (G'37- (3"37) provided that the other rheological conditions are met, increases the internal cohesiveness of the topical adhesive, and decreases the possibility of remaining adhesive residues. on the skin upon removal of the topical adhesive. 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 met: • 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 in the scale from 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 in the scale from 0.7 to 3, most preferably on the scale from 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 no 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 difference ? (G'37-G "37) (1 rad / sec) is greater than or equal to 1250 Pa, preferably greater than or equal to 2500 Pa, more preferably greater than or equal to 3500 Pa. In addition preferred conditions are also: • the value of the ratio G'37 / G "37 at least for the frequency scale of about 1 rad / sec to 100 rad / sec, should preferably be 3.3 or higher, more preferably 5 higher, more preferably 10 or higher , while not exceeding about 30, preferably 20, 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 topical adhesive can also be related to the specific heat capacity. Preferably, the heat capacity Specific to the topical 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 topical adhesive can 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 Composition Characteristics of a Topical Adhesive In order to provide topical adhesive compositions that meet the requirements of the rheological and physical characteristics of a topical adhesive above, the following formulation criteria should be used. It should be noted that most of the compositions useful as the topical 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 polymeric substance or a mixture of these soluble substances or able to inflate 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 Block Copolymer Elastomers 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 45 to 99.5% by weight, preferably from 51 to 99.5% by weight of a plasticizer or a mixture of plasticizers, 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 50% by weight of the composition, preferably 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 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 C fatty acids, their metal salts and their polyoxyl derivatives; lanolin derivatives, silica; bentonite, montmorillonite and its derivatives; polyamides, waxes or mixtures thereof.

Common additives known in the art as preservatives, antioxidants, anti-ultraviolet agents, pigments, mineral fillers, rheology modifiers, etc., may also be comprised in amounts of up to 10% each. When chemical lattices are formed in the system, a crosslinking agent may be present in amounts of up to 5% by weight. Chemical crosslinking can also be formed by the mutual neutralization of polymers having different functionalities as in the reaction between polyacrylic acids and polysaccharides. The compositions for topical 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) Hydrophobic compositions in which the plasticizer is typically an oil or mixtures of oils of vegetable and mineral origin and the polymer is normally a synthetic polymer, preferably an elastomer, soluble, or able to swell 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 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 phase polymeric is of synthetic origin (for example polyacrylics), or natural (for example natural gums) or mixtures thereof. It is important that, unlike the medical field and 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 the 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 topical adhesive with the liquid being absorbed. Since the liquids are, all of a general aqueous type, in contact with a topical hydrophilic adhesive, it would result in a certain absorption of the body fluids in the topical adhesives. This would then have the result of changing the rheological characteristics and therefore the functionality of the topical adhesive and cause an unhygienic appearance. In addition, the hydrophilic topical adhesive also tends to be perceived as cold and wet which upon application to a human skin is not in line with the typical expectation. Additional problems result from the fact that particular topical adhesives comprising water as the plasticizer have a tendency to dry unless sealed in a waterproof package.

Application of Topical Adhesive Absorbent articles in which topical adhesive can be used according to the present invention, they can be made by any of the usual ways of the art. The application of the adhesive to the top sheet side of an absorbent article should not cause greater problems for those skilled in the art since it can be provided by any of the well-known techniques commonly used for other adhesives. The total area of the skin or surface that faces the user of an article that is covered by the topical adhesive should not be greater than 20%, preferably not greater than 10%. Preferably, the adhesive is near 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 that is not permeable to liquids. More preferably, the adhesive is provided in a pattern of small increment areas such as dots or the like. The topical adhesive is applied on at least part of the user-facing surface of the disposable absorbent articles in a layer having a thickness or caliper which is preferably constant, or which may alternately vary on the surface of interest by the application of the topical adhesive. If possible, the article also provides breathability by being at least permeable to water vapor, preferably permeable to air to prevent it from being poorly ventilated. The breathability, if not supported or maintained by the topical adhesive as such, may be limited to the area of the article where no adhesive is applied. The topical adhesive in an article is preferably protected before use. This protection can be provided by a release liner such as a paper treated with silicone or surfactant, providing easy detachment of the selected topical adhesive. This invention can be used beneficially in articles Disposable absorbent that is applied directly to the skin of a user. The article normally exhibits absorbency of bodily fluids, the protection of the user's garments against staining is convenient to use, and is easy to produce and pack. The disposable absorbent article is described below with reference to a sanitary napkin or catamenial producthowever, pantiliners, 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 (e.g. vaginal, menstrual and / or urine), and which are intended to be discarded after a single use. A disposable absorbent article is preferably thin, more preferably between 1 and 5mm thick and, either, substantially planar before use or in a preconfigured 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 indirectly connected to a second member by connecting the first member to intermediate members who in turn are connected 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 on which the topical adhesive is applied and a surface that faces the garment or that is in contact with the garment. The top sheet is docile, soft feeling, and non-irritating to the skin of the user, the top sheet may also have elastic characteristics that allow it to be stretched in one or two directions, in parts of the upper sheet, or in its entirety. In addition, the topsheet is permeable to fluid, allowing fluids (eg, menses and / or urine) to easily penetrate through its thickness. The preferred top sheets for use in the present invention are typically selected from the upper nonwoven sheets with raised upper region and upper sheets of film formed with openings. Films formed with openings are especially preferred for the upper sheets because they are permeable to body exudates and not yet absorbent, and have a reduced tendency to allow the fluids to pass back through and rewet the user's skin . In this way, the surface of the formed film that is in contact with the user remains dry, thus reducing the staining of the body and creating a more comfortable feeling for the wearer. Suitable formed 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 United States Patent No. 5,006,394. Top sheets of film 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 formed film described in one or more of the above patents and sanitary napkins are marketed by The Procter & Gamble Company of Cincinnati, Ohio as "DRI-WEAVE". Topical adhesives are very well used on top sheets that do not have a homogeneous liquid passages distribution but only a part of the top sheet that comprises the liquid passages oriented in such a way that they result in a centrally permeable and peripherally permeable upper sheet to the liquids. 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 Publication Nos. WO 93/09744; WO 93/11725 or WO 93/11726. When we refer to the top sheet, a multi-layered structure or a single layer structure is contemplated. The hybrid top sheet mentioned above, is this multi-layered design, but other multi-layered top sheets such as the primary and secondary top sheet designs are also considered. The absorbent core can also comprise multiple layers and provides the function of fluid storage and distribution. Placed in fluid communication with, and typically underlying, the top sheet, is the absorbent core. The core may comprise any normal absorbent material or combinations thereof. This preferably comprises gelling absorbent materials, generally referred to as "hydrogel", "superabsorbent", "hydrocolloid" materials in combination with suitable carriers. The gelling absorbent materials suitable for use herein will often comprise a partially neutralized, lightly crosslinked polymeric gelling material, substantially insoluble in water. This material forms a hydrogel upon contact with water. These polymer materials can be prepared from acid-containing, unsaturated, polymerizable monomers, such as acrylic acid, which are well known in the art. Suitable carriers include materials that are conventionally used in absorbent structures such as natural, modified or modified fibers. synthetics, particularly modified or unmodified cellulose fibers in the form of fluff and / or tissue. Suitable carriers can be used together with the gelling absorbent material, however, these can also be used alone or in combinations. Tissue and tissue laminates are very preferred, in the context of sanitary napkins / linings. One embodiment of the core, particularly useful in the application of the present invention, comprises a laminate of double-layer tissue formed by folding the tissue over itself. These layers can be joined together. The gelling absorbent material or other optional material can be comprised between the layers. The absorbent core may include optional components normally present in the absorbent webs such as odor control agents, in particular suitable zeolites. The backsheet primarily prevents the exudates absorbed and contained within the absorbent core from wetting articles that come into contact with the absorbent product such as underpants, briefs, pajamas, and undergarments. The backsheet is preferably impervious to liquids (e.g., menses and / or urine and is usually manufactured from a thin plastic film.) The backsheet typically extends throughout the entire absorbent core and can extend over and form a part. of the top sheet, bending around the absorbent core In this way a preferred 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 of Selectively perforating the top sheet Preferably, the backsheet also provides breathability to the absorbent article by being at least permeable to water vapor, preferably permeable to air The backsheet can be a laminate, for example, a combination of microporous film, and / or a non-woven material, and / or film formed with openings. The breathability, if desired, may be limited to the periphery or the center of the backsheet, or this may be throughout the entire back sheet. In order to evaluate the effect of the difference? (G'37- < 3"37) of the stickers »Topical according to the present invention, on the amount of residues of the adhesive remaining on the skin by removing the topical adhesive, the residue test has been developed. In this test, the adhesion of a standard substrate, provided with a layer of topical adhesives characterizing a given value of? (G'37- <3"37) is achieved on the skin of a forearm of a user and subsequently evaluates the successive removal of the amount of adhesive residues that remain on the skin.

Proof of the residue The residue test is used to evaluate the amount of adhesive residues that remain on the user's skin, after removing a sample provided with a topical adhesive layer and that was previously fixed to the skin of the user's forearm. The test specifically evaluates the amount of adhesive residue as the residual stickiness on the skin caused by the adhesive residues, in terms of the peak tension force (N), necessary to disengage a standard steel plate adhered to the skin after removal. the sample with the topical adhesive.

Sample Preparation The test is performed on rectangular samples of 50 x 20 mm, made of a 23 micron thick polyester film, such as that sold by Effegidi S.p.A. of Colorno (Parma, Italy), provided on one side with a continuous layer of Selected topical adhesive that has a constant thickness of 1.25 mm applied with an acumeter striker model LH-1. A release paper is applied to protect the adhesive layer. The samples are prepared individually and tested after one hour of preparation. Apparatus 1) Climate controlled laboratory Maintained at 23 ° C and 50% relative humidity. 2) Dynamometer Model 6021, Instron Limited GB Load cell = 10 N Test speed = 1000 millimeters / minute 3) Weight Cylindrical weight of 1 kg with 44 mm diameter and 82 mm height. 4) Cardboard plate 60 x 60 mm square cardboard plate 5) Steel plate Rectangular steel plate of 50 x 60 mm with a flat, smooth surface, and provided with means for connection to a mobile holder of the dynamometer.

Measurement of the residue No special treatment of the user's skin beyond normal cleaning / washing with soap and water and drying for at least 2 hours before the test, to allow the skin to reach equilibrium with environmental conditions. A rectangular area approximately 10 mm long and wider than the dimensions of the sample on the inner part of the user's forearm skin, for example, is selected. drawing it on the skin with adequate means, with the area centered between the wrist and the elbow, with the longest side of the area aligned with the length of the arm. The sample is then applied on the skin by an operator, being centered with respect to the previously defined selected area, and a pressure is exerted on it by placing the weight on the sample by hand and leaving it there for 30 seconds, with the cardboard plate interposed between the weight and the sample in order to cover the total sample area. After removing the weight and the cardboard plate, the sample is used by the user for one hour, and then the sample is removed with the topical adhesive from the skin of the user's forearm by the operator with a slow and slow shot, without Touch the skin where the sample was applied. The steel plate is connected to the moving upper bracket of the dynamometer in such a way that its flat surface is placed horizontally, perpendicular to the direction of movement of the fastener, and giving down. The user places his arm horizontally on a suitable support under the mobile clamp of the dynamometer, with the selected area of the skin where the sample has been applied, placed directly below the steel plate. The forearm of the user and the steel plate on the fastener are placed and oriented mutually in such a way that the steel plate is centered with respect to the selected area of the forearm, the larger dimensions of the plate and the selected area being parallel, and with the surface of the steel plate and the forearm skin in the selected area approximately parallel to each other. The Instron is operated to move the fastener with the steel plate towards the selected area until full contact is achieved between the flat surface of the steel plate and the skin, and a compression force of 9.8 N is applied for 30 seconds. , then the fastener is achieved and the measured peak force in Newton (N) required to disengage the steel plate from the selected area is recorded as a measurement of the amount of the residue. The measurements are carried out and averaged over 5 samples of the same type, to ensure that a representative residue value is determined for the sample under investigation. The amount of adhesive residues left on the skin after removing the topical adhesive has been evaluated for two different samples A and B provided with two different topical adhesive compositions according to the present invention. Sample A and sample B are provided with a topical adhesive layer according to composition 1 and composition 2, respectively, as described below.

COMPOSITION 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 modulus 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 '^ dOO rad / sec) - G'X (100 rad / sec) G'37 (1 rad / sec) - G "37 (1 rad / eg) = 1.22 e) The proportion of G'37 on G'37 (1 rad / sec) was 0.308, with? G'37 = 2124 Pa.

COMPOSITION 2 A topical adhesive is an oil-based composition containing 10% by weight of Krato G-1651, a styrene / ethylene / butylene / styrene block copolymer available from Shell Co., 49% by weight of Kaydol, an oil paraffinic mineral available from Witco Co., 40% by weight of Escorez 5300, a hydrogenated tackifier resin available from Exxon Co., 0.7% by weight of magnesium stearate, a co-gelling agent available from Cerlo Erba, SpA, and 0.3% by weight of Irganox 1010, an antioxidant available from Ciba Geigy. Finally, the formulation had the following percentage composition: Kraton G-1651 10.0% by weight Kaydol 49.0% by weight Escorez 5300 40.0% by weight Magnesium stearate 0.7% by weight Irganox 1010 0.3% by weight The composition shown has the following rheological properties at 37 ° C. a) Elastic modulus at 1 rad / sec G'37 = 7038 Pa b) Viscous module at 1 rad / sec G "37 = 487 Pa c) Proportion of Elastic and Viscous Modules at 1 rad / sec, G'37 / G "37 = 14.45 d) Proportion of G '^ dOO rad / sec) - G" ^ (100 rad / sec) G'37 (1 rad / sec) - G "37 (1 rad / eg) = 1.11 e) The ratio of? G'37 over G'37 (1 rad / sec) was 0.291, with? G'37 = 2051 Pa. The results of the test are summarized in the following table: The results show that the increases in the values of the difference? (G'37-G "37) correspond to the minor amounts of the adhesive residues left on the wearer's skin after the removal of the topical adhesive compositions according to the present invention.Furthermore, the compositions of the topical adhesive according to the presnete invention, have been judged as comfortable for the initial application and for the removal of hairy, sensitive skin, without causing pain.

Claims (7)

1. A topical adhesive to fix an article to the skin, said adhesive having an elastic modulus at a temperature of 37 ° C (100 ° F), G'37l and a viscous modulus at a temperature of 37 ° C (100 ° F), G "37, and a difference? (G'37- G" 37) between said elastic modulus G'37 (rad / sec) and said viscous modulus G "37 (rad / sec), 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 on the scale of 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 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 in 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 of them, the difference? (G'37 - G "37) (rad / sec) is greater than or equal 1250 Pa, it is preferably greater than or equal to 2500 Pa, most preferably greater than or equal to 3500 Pa.

2. A topical adhesive according to any preceding claim, characterized in that said adhesive is provided as a continuous layer.

3. A topical adhesive according to any of the preceding claims, comprising: from 45% to 99.5%, preferably from 51% to 99.5%, by weight a plasticizer compound or composition which is liquid at 20% C; 0.5% to 20% by weight of a compound or polymer composition that is soluble or swellable in the plasticizer composition or composition; a tackifying resin in an amount of 0% to 50% by weight, preferably 0% to 600% by weight of the compound or polymer composition.

4. The topical adhesive according to claim 3, wherein said plasticizer compound or composition is selected from the following group: water, alcohols, glycols, oil or combinations thereof; and said polymeric compound or composition is selected from the following group: block copolymer thermoplastic 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.

5. A topical adhesive 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.

6. A disposable absorbent article such as a sanitary napkin or a panty protector for topical adhesive attachment to a wearer's skin, said article having a surface facing the wearer and a garment facing surface and comprising an absorbent core between the wearer and the wearer. surface facing the user and the surface facing the garment, said article comprising on at least part of the surface facing the body a topical adhesive according to claim 1 for topical adhesive fixation of the article.

7. The use of a topical adhesive according to claim 1 in a disposable absorbent article such as a sanitary napkin or a panty protector.