CZ217399A3 - Disposable absorption article for external adherent attachment to bearer's skin - Google Patents

Abstract

The invention relates to disposable absorbent articles, in particular sanitary napkins, panty liners, products at adult incontinence or sweat pads that are worn direct attachment to the wearer's skin in the area where it is desirable fluid uptake. Disposable absorbent article includes at least a portion of the surface facing the wearer adhesive adhesive external adhesive connection of the product to the skin wearer. Given the elastomeric modulus of elasticity at 37 ° C C, abbreviated as G * 37, the viscosity modulus at tel 37 ° C, G n37. The adhesive is selected to have a dynamic elastic behavior such that the difference of -G * 37 from the G’37 frequency applied loads 100 rad / sec. and G * 37 at frequency applied loads of 1 rad / sec, not more than 150% 80% of G * 37 at 1 rad / sec. or preferably smaller than 10,000 Pa. The adhesive is further selected to have dynamic viscous behavior such that the difference - Gn37 from Gn37 at a load rate of 100 rad / sec. aGu37 at the applied load frequency of 1 rad / sec is not greater than 10 Pa, preferably not more than 5,000 Pa and more preferably not greater than 1000 Pa.

Description

A disposable absorbent article for externally adhering attachment to the wearer's skin

Technical field

The present invention relates to disposable absorbent articles, in particular sanitary napkins, panty liners, adult incontinence products or sweat pads. In particular, the invention relates to such disposable absorbent articles that are worn by directly attaching them to the wearer's skin in an area where fluid absorption is desired.

BACKGROUND OF THE INVENTION

The prior art in the field of disposable absorbent articles for external application to the wearer's skin is particularly developed in the field of leucotapes, patches and dressings. However, these articles are typically used in emergency situations where, for example, the wearer has been cut and it is desirable to absorb body fluids from the wound. In this context, the performance aspects of a certain absorbent article, such as convenient and easy to use and apply, painless removal and unobtrusiveness, are subject to measures such as sterility, healing support and mechanical wound protection. These wounds covering absorbent articles are mostly used in skin areas where hair can be removed or no hair grows before applying the absorbent article.

The present invention does not relate to wounds covering absorbent articles, but relates to absorbent articles for absorbing body fluids that naturally flow out of the body without any injury. Such articles are, for example, sanitary napkins or panty liners for use in the genital area. The present invention also relates to devices worn during incontinence in the genital area or sweat pads worn by persons under the armpit.

These products are applied to the skin of the wearer in an area where a significant amount of hair typically grows, so that aspects of easy and painless removal of the article are of key importance. Such articles are generally described in the description of the invention US H 1602 or WO96 / 33683. More details about these products are considered, for example, in PCT application WO 95/16424. Described herein are sanitary articles having an adhesive for applying to the body that is applied along the entire circumference to the side of the sanitary napkin facing the wearer. The problem accompanying this document is in the first place a secure attachment to the skin, but also the problems of releasing these products after use, without causing undue pain to the wearer, are also mentioned.

The disclosure of WO 95/16424 discloses a detailed analysis of the scales for an adhesive to be applied to the body, with respect to rheology aspects (i.e., general teachings on the deformation behavior of substances). However, this document pays little attention to the problem of painless removal of these products because the rheological measures mentioned include epilating, ie hair removal, products commercially available such as SHELF MIELE ™, sold in Italy by Vaj SpA Laboratories. mentioned in WO 95/16424 also contain today's self-adhesive adhesives which are used to attach sanitary napkins to underwear components. Furthermore, this document identifies only static rheological characteristics, but does not speak of the dynamic rheological behavior of the body adhesive.

WO 96/13238 discloses a body-to-body adhesive model based on the frequency (frequency) of the applied stresses (stresses, pressures, hereinafter referred to as "loads"). However, all the measurements described, for example on page 9, were performed at temperatures between -60 ° C and + 120 ° C and at actual applied load frequencies from 0.1 to 100 rad / sec. In order to obtain the necessary data at the loading temperature (about 20 ° C, typical bath, i.e. storage temperature), the equation of Williams, Landel and Ferry (hereinafter referred to as WLF) was used.

The WLF equation is empirical and does not apply within certain limits, for example it cannot be used to extrapolate (ie to estimate) temperatures below the glass transition temperature of a polymer adhesive, and the WLF equation cannot be used based on the values obtained below the glass transition temperature. Details of the WLF equation and its applicability can be found in "Polymer Processing Principles" by Z. Tadmor and C.G. Gogos, published by John Wiley and Son, or in "Viscoelastic Properties of Polymers," by J.D. Ferry, also published by John Wiley and Son. Since this is already lacking in WO 96/13238, the applicability of the described data cannot be evaluated.

European patent application EP-638 303 discloses the use of an adhesive to be applied to the body on the side cuffs of sanitary napkins in order to keep these cuffs in an upright position. Swiss publication CH-643 730 discloses the use of a very long sanitary napkin having bevelled outer edges, with an adhesive for adhering to the body at four corners. · · ··· ·· · ········ These outer edges, in order to provide an area of adhesive for application to the body sufficiently outside the pubic (pubic) hair region.

Accordingly, it is an object of the present invention to provide disposable absorbent articles for absorbing naturally flowing fluids from the wearer ' s body that are attached to the wearer's skin while providing painless removal of the absorbent article. It is yet another object of the present invention to ensure that no adhesive remains on the skin or on the wearer's hair when the absorbent article is removed. It is another object of the present invention to provide a disposable absorbent article that is worn in close proximity to the area of fluid flow from the wearer's body so that fluid loss to the exterior of the absorbent article is minimized or eliminated. For disposable absorbent articles worn in the crotch region of the wearer, this results in increased safety against contamination of the surrounding skin tissue and clothing.

In addition to the above objects of the present invention, it is also desirable that sanitary napkins, panty liners, and menstrual articles reduce or even eliminate odor emanating from the article, since its application to the wearer's skin provides an odor seal that prevents odors from absorbed or formed liquid. from absorbed liquid, get away from the absorbent article.

SUMMARY OF THE INVENTION

The present invention relates to disposable absorbent articles for external adhesive attachment to the wearer of such articles. This article typically has a wearer facing surface and an outer surface, in the context of articles worn under clothing, also called a garment surface.

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The article includes an absorbent core structure between a wearer facing surface and a garment facing surface to absorb fluids naturally flowing from the wearer's body. The disposable absorbent article of the present invention includes an adhesive for at least a portion of the wearer facing surface for externally adhering attachment of the article to the wearer's skin.

The adhesive is particularly characterized by having a modulus of elasticity at 37 ° C (100 ° Fahrenheit), abbreviated to G ^T 37, and having a modulus of viscosity at 37 ° C (100 ° Fahrenheit), GI ^: 37. The adhesive is selected so that it has dynamic elastic behavior such that a difference of -6 ^τ 37 of G ^x 37 at the frequency (frequency) of applied stresses (stresses, pressures; hereinafter referred to as "applied load") 100 rad / sec. and G ^I 37 at the frequency of the applied load of 1 rad / sec., not greater than 150%, preferably 80%, of G ^T 37 at 1 rad / sec. or preferably less than 10,000 Pa. The adhesive is further selected to have a dynamic viscous behavior such that the difference -G ^IX 37 from G ^{i: t} 37 at a applied load frequency of 100 rad / sec. and G ^TI 37 at a applied load frequency of 1 rad / sec, is not more than 10,000 Pa, preferably not more than 5,000 Pa, and most preferably not more than 1,000 Pa.

It is particularly preferred that the products of the present invention have a ratio value of G ^T 37 over Ο ^Ι] · 37 over the entire applied frequency range of 1 to 100 rad / sec. greater than or equal to 1, preferably greater than or equal to 1.6, and most preferably greater than or equal to 3.3.

The value of the ratio 6 ^l 37 over G ^{i: c} 37, at least for an applied load frequency range of 1 to 100 rad / sec, may vary with increasing applied load frequency, although it is not necessarily proportional to the change in this frequency. This ratio G ^I 37 over G ^{i: t} 37 should not be varied by a factor of more than 3 within the frequency range of the applied loads, · · · 37 · · · · · · · · · The composition by weight is an alcohol, a polymer compound, preferably selected from preferably more than 2 and most preferably should remain constant.

In row 1, the preferred value of G ^I 37 below 20000 Pa, preferably below 15000 Pa and most preferably even less than 10000 Pa. On the other hand, the ^GJ value of 37 would be 1 rad / sec at the applied load frequency. it should preferably be less than 10,000 Pa and most preferably less than 5,000 Pa. The above rheological aspects can be met by adhesive compositions which comprise from 51% to 99.5% of a softening compound or composition that is liquid at 20 ° C; 0.5 to 20%, preferably 5 to 15%, of a polymer compound or mixture that is soluble or swellable in the softening compound or mixture; and attaching the resin-enhancing agent in an amount ranging from 0% to 600%

The softening compound or groups comprising water, preferably glycerol, glycols, polyglycols, liquid polybutenes, oil or combinations thereof, while the polymeric compound or mixture is preferably selected from the group consisting of block copolymer thermoplastic elastomers, styrene block copolymers and hydrogenated styrene block copolymers.

Quite generally, the preferred body adhesive is at least partially hydrophobic (ie, water repellent), preferably 60%, more preferably 80%, the weight of the adhesive consists of hydrophobic components, and most preferably none of the materials in the adhesive is hydrophilic, i.e. hydrophobic components.

In particularly preferred embodiments of the present invention, the adhesive covers less than 20%, or even preferably less than 10%, of the surface facing the wearer of the absorbent article. The present invention is most beneficially used in the field of sanitary napkins or panty liners.

• · · · · · · · · · · · · · ·

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to disposable absorbent articles which are applied directly to the user's skin. This product exhibits body fluid absorbency, protects user's underwear components from contamination, has enhanced physical comfort for wearers, is easy to manufacture and pack. This disposable absorbent article is described below by reference to a sanitary napkin or sanitary napkin, but the term disposable absorbent articles also includes panty liners, adult incontinence products, or sweat suction pads ("wadding"). The term "sanitary napkin, as used herein, refers to a product worn by women adjacent to their pudendal (pubic) region and the retention is intended to be used to absorb and various body fluids that are secreted from the body (e.g. , vaginal secretions, menses and / or urine) and are expected to be discarded after a single use. The disposable absorbent article is preferably thin, more preferably between 1 and 1.5 mm thick and either substantially flat before use or in a preformed form.

The terms "bonded or" attached, as used herein, include arrangements by which a first portion is directly attached to a second portion and those arrangements by which the first portion is attached to a second portion indirectly by attaching the first portion to intermediate portions that are in turn connected to the first part.

In a preferred embodiment, the sanitary napkin of the present invention comprises a liquid pervious topsheet, a liquid impermeable backsheet attached to the topsheet, and an absorbent core encapsulated between the topsheet and the backsheet. The sanitary napkin has two main surfaces,

··

9 9

9

9999 99

999 9 99 • · the body-facing surface of the wearer and the surface facing or contacting the laundry.

The topsheet is flexible, soft feeling and non-irritating to the wearer's skin. The topsheet may have elastic characteristics allowing it to be stretched in one or two directions in portions of the topsheet or throughout its extension. Further, the topsheet is liquid pervious and allows fluids (e.g., menses and / or urine) to readily penetrate through its thickness. A suitable topsheet may be manufactured from a wide range of materials such as woven and nonwoven materials; polymeric materials such as apertured formed thermoplastic films, apertured plastic films and hydroformed thermoplastic films and thermoplastic scrims. Suitable woven and nonwoven materials may be composed of natural fibers (e.g., wood or cotton fibers), synthetic fibers (e.g., polymer fibers such as polyester, polypropylene or polyethylene fibers), bicomponent fibers, or a combination of natural and man-made fibers, or multi-component fibers.

Preferred topsheets for use in the present invention are typically selected from highly expanded, nonwoven topsheets and apertured formed film topsheets. The apertured formed films are particularly preferred for the topsheets because they are permeable to body exudates while still remaining non-absorbent, and have a reduced tendency to allow fluids to flow back and rewet the wearer's skin. Thus, the surface of the formed film that is in contact with the wearer remains dry, thereby reducing body contamination and creating a more comfortable feel for the wearer. Suitable formed films are described in U.S. Patent 3,929,135; U.S. Pat. No. 4,324,246; U.S. Patent 4,342,314; U.S. Patent 4,463,045; and U.S. Pat. No. 5,006,394. Particularly preferred, micro-apertured formed film topsheets are described in < Desc / Clms Page number 3 > In U.S. Pat. No. 4,609,518 and in U.S. Pat. No. 4,629,643. the layer for the present invention comprises the formed film described in one or more of said patents and sold on sanitary napkins by The Procter & Gamble Company of Cincinnati, Ohio under the trademark " DRI-WEAVE.

The invention also envisages topsheets not having a homogeneous (homogeneous) distribution of fluid passageways, but only a portion of the topsheet comprising fluid passageways. Typically, such layers would have fluid paths oriented so as to result in a mid-permeable and peripherally impermeable topsheet. The wearer facing surface of the formed film topsheet may be hydrophilic to assist fluid transfer through the topsheet faster than if the body surface was not hydrophilic. In a preferred embodiment, an active surfactant is incorporated into the polymeric materials of the formed film topsheet as described in PCT publication WO 93/09741. Alternatively, the wearer facing surface of the topsheet may be made hydrophilic by treatment with a surfactant, as described in US 4,950,254.

Yet another alternative is the so-called hybrid topsheets having incorporated fibrous and foil-like structures, particularly useful embodiments of such hybrid topsheets are described in PCT publications WO 93/09744; WO 93/11725 or WO 93/11726.

When referring to the top layer, the multilayer or monolayer structure is anticipated. The hybrid topsheet mentioned above is such a multilayer embodiment, but other multilayer topsheets are contemplated, such as those with primary and secondary topsheets.

The absorbent structure or absorbent core may comprise the following components: (a) optionally a primary fluid distribution layer, preferably together with a secondary fluid distribution layer; (b) a fluid storage layer; (c) · c c c c c c c c

9 9 9 9 9 9

9

9 99 9 9 ···· Optionally a fibrous (dust) layer lying under the storage layer; and (d) other optional components.

(a) Primary / secondary fluid distribution layer

One of the optional components of the absorbent structure of the present invention is a primary fluid distribution layer and a secondary fluid distribution layer. The primary fluid distribution layer typically lies below the topsheet and is in fluid communication therewith. The topsheet transfers the acquired fluid to this primary distribution layer for final distribution to the storage layer. This fluid transfer through the primary distribution layer occurs not only in thickness, but also along the length and width directions of the absorbent article.

Also, an optional but preferred secondary fluid distribution layer typically lies below the primary fluid distribution layer with which it is in fluid communication with the fluid. The purpose of this secondary distribution layer is to readily receive fluid from the primary distribution layer and rapidly transfer it to the underlying storage layer. This helps the capacity of the underlying storage layer to be fully utilized. The fluid distribution layers may be comprised of any material typical of such distribution layers. Fiber layers which hold the capillaries between the fibers even when wet are particularly useful as these distribution layers.

(b) Fluid storage layer

The fluid storage layer is disposed in fluid communication with the fluid and typically lies below the primary and / or primary layers

φφ φφφφ «

φ φ

φ φ sekund φ φ φ φ φ φ φ φ sekund sekund sekund φ φ φ φ The fluid storage layer may comprise any conventional absorbent material or combinations thereof. Preferably, it comprises absorbent gelling materials which are generally referred to in conjunction with suitable carriers such as hydrogel, superabsorbent and hydrocolloid materials.

These absorbent gelling materials are capable of absorbing large amounts of aqueous body fluids and are further capable of holding these absorbed fluids under moderate pressures. These absorbent gelling materials can be dispersed homogeneously or homogeneously in a suitable carrier. Suitable carriers, provided that they are absorbent as such, may be used alone.

Suitable absorbent gelling materials for use herein most often comprise a substantially water-insoluble, slightly crosslinked, partially neutralized polymer gel material. This material forms a hydrogel upon contact with water. Such polymeric materials can be prepared from polymerizable, unsaturated, acid-containing monomers that are well known in the art.

Suitable carriers include materials that have traditionally been used in absorbent structures such as, for example, natural, treated or artificial fibers, especially treated or untreated cellulose fibers, in the form of fluff and / or tissue paper. Suitable carriers may be used together with the absorbent gelling material, but may also be used alone or in combination. In the context of sanitary napkins / panty liners, tissue paper or laminates thereof are most preferred.

One embodiment of the absorbent structure made in accordance with the present invention comprises a double layer of tissue paper laminate formed by folding it on itself. These layers

4 «« 4 4 4 4

4 4 4 4

4444 44 4 · • Ml · 4 4 4

4 4 4 «• 4,444,444

4 4

44 44 can be connected to each other. An absorbent gelling material may be included between the layers.

Treated cellulose fibers, such as stiffened cellulose fibers, may also be used. Synthetic fibers may also be used and include those made from cellulose acetate, polyvinyl fluoride, polyvinylidene chlorine, acrylic resin (such as Orion), polyvinyl acetate, insoluble polyvinyl alcohol, polyethylene, polypropylene, polyamides (such as nylon), polyesters, bicomponent fibers, triple component fibers, mixtures thereof, and the like. The fibrous surfaces are preferably hydrophilic or treated to be hydrophilic. The storage layer may also contain filler materials such as Perlite, diatomaceous earth, Vermiculite, and the like that improve fluid retention.

However, if the absorbent gelling material is dispersed heterogeneously in the carrier, the storage layer may, however, be locally homogeneous, i.e., have a distribution gradient in one or more directions within the dimensions of a particular storage layer. The inhomogeneous distribution may also refer to carrier laminates encapsulating partially or completely absorbent gelling materials.

(c) Optional fibrous (dust) layer

The optional component for inclusion in the absorbent structure of the present invention is a fibrous layer adjacent to and typically lying below the storage layer. This backing fibrous layer is typically referred to as a dusting layer because it provides a substrate to which the absorbent gelling material is deposited in the storage layer during manufacture of the absorbent structure. Indeed, in those cases where the absorbent gelling material is in the form of ft gel podobě ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft · ft Macrostructures such as fibers, layers, or strips, this fibrous dust layer may not be included. However, this dust layer provides some additional fluid management capacities such as rapid fluid leakage along the length of the pad.

(d) Other optional components of the absorbent structure

The absorbent structure of the present invention may contain other optional components normally present in absorbent structures. For example, a reinforcing scrim may be located within or between the respective layers of the absorbent structure. These reinforcing scrims should be arranged so that they do not form obstacles at the interfaces for fluid transfer between surfaces. Assuming that structural integrity usually results from thermal bonding, these reinforcing scrims are not usually required for thermal bonded absorbent structures.

Another component that may be included in the absorbent structure of the present invention and is preferably provided at or as part of the primary or secondary fluid distribution layer is odor control means. The absorbent structure typically incorporates activated carbon that is coated with or in addition to other odor control agents, particularly suitable zeolite or clay materials. These components can be incorporated in any desired form, but are often included as fine, unobtrusive particles.

First, the backsheet prevents absorbed and retained exudates in the absorbent structure from wetting articles that contact the absorbent article, such as panties, pajamas, trousers, and undergarments. This backsheet is preferably liquid impervious (e.g.

menses and / or urine) and is preferably made of a thin plastic film, although other flexible and liquid impervious materials may also be used. As used herein, the term flexible refers to materials that are compliant and easily conform to the overall shape and contours of the human body. The backsheet may also have elastic characteristics,

allowing her to in two directions. se flexibly protahovala v one or ve Bottom layer se typical flexing through whole absorption structure and can se also stretch into and shape the part

the topsheets by folding around said absorbent structure. As a result, the topsheet arrangement as described in US 4,342,314, column 16, lines 4762 can be achieved without requiring selective topsheet perforation.

The backsheet may consist of a woven or nonwoven material, polymeric films such as thermoplastic films of polyethylene or polypropylene, or composite materials such as a film-coated nonwoven material. Preferably, the backsheet is a polyethylene film having a thickness of from about 0.012 mm (0.5 mils) to about 0.051 mm (2.0 inches).

Exemplary polyethylene films are manufactured by Clopay Corporation of Cincinnati, Ohio under the designation P18-O4O1, and Ethyl Corporation, Visqueen Division of Terre Haute, Indiana under the designation XP-39385. The backsheet is preferably embossed and / or finished with a matte surface to provide a more clothlike appearance.

Preferably, the backsheet also provides breathability to the absorbent article by being at least partially vapor permeable, preferably air permeable, but without impairing the main function of the backsheet itself. The backsheet may be some laminate material, for example,

a combination of microporous film, nonwoven material and / or apertured formed film. The breathability, if desired, may be limited to the periphery of the backsheet or may be across the entire backsheet.

External Connection Agents

The products of the present invention, as mentioned above, are applied directly to the wearer's skin. In particular, sanitary napkins are applied in the genital area of a typical female wearer, around the area of the fluid outlet. The word "skin of the present invention not only refers to the particular skin of the wearer, but also includes mucosal tissue as well as hair typically found in the genital area of sanitary napkin users.

In order to secure the article of the invention to the user ' s skin, it is necessary to provide a certain area on the side of the topsheet facing the wearer with an external attachment adhesive, also referred to as a body adhesive. .

In this regard, various embodiments are contemplated, but preferably, the body-facing adhesive is provided along the peripheral edge of the topsheet such that the central portion of the article is left free of adhesive. This most conveniently facilitates positioning of the article such that the adhesive-free liquid-permeable topsheet is disposed adjacent the body fluid outlet opening such that the effluent fluid is immediately transferred to the absorbent structure of the absorbent article, without the possibility of leakage or spillage.

However, it is not necessary for the body-facing adhesive to be provided in a closed circle around the perimeter of the topsheet, but may be provided in additional areas. · · · · · · · ··· ······································································· .

In order to meet the objectives of the present invention, the following should be met.

Physical, rheological and adhesion characteristics of body adhesive

Although the body adhesive is used as a self-adhesive adhesive for the scalp of human skin and mucous tissue, it is understood that the body adhesive compositions could hardly be regarded as typical self-adhesive adhesives (hereinafter referred to as self-adhesive adhesives as “PSA” based on the most characteristic rheological behaviors of these materials.

In fact, the adhesive specialist knows that the most characteristic feature that differentiates PSA from other substances that can temporarily adhere to things (as could, for example, water) is that their rheological parameters, and especially the elastic modulus of G ^{* 1} , can widely change with the frequency of applied stresses (pressures, stresses; hereinafter referred to as “applied loads, pos. transl.). In addition, in particular, G ¹ in PSA may increase by several orders of magnitude, while the applied load frequency varies from a typical applied load frequency to a typical applied load load frequency, ie, from 1 rad / sec to 100 rad / sec. as shown below.

As a first consequence, it is unacceptable to define the materials envisaged for use as an "adhesive" by providing rheological parameter values, and in particular G ¹ at a fixed frequency value.

4 · ·· 4,444

444 4444

444 44 4 444444

444445 4 4

444444 44 4 44 44 applied loads. This can be misleading because, in the absence of other characteristics, it can lead to the inclusion of materials of no practical value. It is therefore considered that rheological characteristics must be based on dynamic considerations.

This applies not only to the elastic modulus G ^1, but also for the modulus of viscosity G ¹¹ and hence also the value (mass peel "tan) (δ) = Gag ^first It is well known that typical PSAs (self-adhesive adhesives) do not only have a high variation of G ¹ over the applied load frequencies, but that there is also an even greater variation for G ¹¹ , which may approach or even exceed G ¹ , δ becomes about or even greater than 1, especially at the applied load frequencies that are typical for disconnection.

Without wishing to be bound by theory, this can be interpreted as an indication that a large fraction of the energy used for uncoupling is dissipated in internal frictions (so that it is not effective in causing uncoupling), although this causes macroscopically recording a high level of adhesive force .

In order to provide good bonding conditions, i.e. at load rates of about 1 rad / sec, the absolute values of the elastic modulus should not be too high, otherwise the adhesive is too hard and cannot fit tightly or form to the surface to which it is expected adhere. It is also important to have a low absolute value of G ^11, so that this adhesive had good cohesion which is particularly valuable for a direct application to the human body while the material remains soft and capable of adhering to the skin fine.

Finally, the person skilled in the art will also recognize that the glass transition temperature Tg of the self-adhesive (PSA) is a parameter that is useful to better define the completeness of the PSA useful materials group.

As noted above, materials useful as adhesives of the present invention are measured when the reference article is formed to be applied to the body according to a rheological characteristic having a temperature of 37 ° C, such as body temperature and within the frequency range of the applied loads. It has been found that when applied to body-facing adhesives, the adhesive contact is at a low frequency (frequency) of applied loads, while disengagement occurs at the rate of removal of the article. This rate is expressed as a frequency of applied loads of 100 rad / sec, while a low frequency of applied loads of adhesive bond forming was found to exist in the order of 1 rad / sec. Therefore, the frequency range of the applied loads for use according to the present invention is between 1 and 100 rad / sec. The following set of characteristics should be met:

within the frequency range of the applied loads, the percentage variation of the elastic modulus G ^I 37 is less than or equal to 150%, preferably less than 100% and more preferably less than 80%, of G ^T 37 at 1 rad / sec, preferably this variation in absolute terms less than 10,000 Pa. This is accomplished for adhesive attachment to the body exemplified below, although the example Promeon RG-63B, quoted in the prior art, shows in the same range of frequencies applied load variation sizes G ^I 37 331%, which the present invention is not acceptable;

- within the frequency range of the applied loads, the variation of the viscosity module G ^II 37 is not more than 10 000 Pa, preferably not more than 5 000 Pa, most preferably not more than 10 000 Pa;

- value of the ratio G ^I 37 / G ^II 37, at least for the frequency range of the applied loads of 1 rad / sec. up to 100 rad / sec, should preferably be one, 1, or greater, more preferably 1.6 or higher; and

9999

9 9 9 9 · ····

9 9 9 most preferably 3.3 or higher, although preferably 3.3 or higher, though preferably it does not exceed about 50.

It should be noted that G ¹ and G ¹¹ at an application rate of 1 rad / sec. are taken at 37 ° C. In practical use of the articles of the present invention, the actual storage temperature of the article and hence the temperature of the body contact adhesive in use varies widely. For example, a bathroom next to a radiator could store hot in a temperature of up to about 37 ° C, while storing in a storage room or bathroom without heating, but with the window open, could approach 0 ° C during winter. However, since the product of the present invention is applied directly to the skin and the wearer will typically not want to put on a too cold product, the actual temperature of the body adhesive will reach 37 ° C very quickly or will be heated by the wearer before application. Thus, it is believed that the adhesive bonding characteristics are selected most conveniently at body temperature.

As indicated above, rheological behavior can often also be related to the Tg values. In the body adhesive of the present invention, the Tg should preferably be less than -15 ° C, more preferably less than -25 ° C, and most preferably less than -25 ° C.

Chemical and composition related to the characteristics of an adhesive for application to the body

In addition, the following composition measures can be used to meet the requirements of the above rheological and physical characteristics of the body-facing adhesive. It should be noted that most of the compositions useful as an adhesive are as follows: 4 · 44 ···· * ····· · * · «·· · For application to the body has a substantially gel-like structure and are

preferably gels. This Yippee derived by d fact, that: - the predominant component Yippee material liquid when room temperature; - in smaller quantities Yippee present macromolecules! or

polymer component versus plasticizer. This creates, in preferred embodiments, a three dimensional network caused by physical or chemical linkages between molecules. Particularly useful bonds are those present in systems comprising block thermoplastic elastomers.

More specifically, these compositions include:

From 0.5 to 20%, preferably 5% to 15%, by weight of the macromolecules! polymeric substances or mixtures of such substances soluble or swellable in the plasticizer composition (s) below. Since non-limiting examples of such macromolecular or polymeric substances may be natural and / or synthetic such as natural gums or derivatives such as natural rubbers and gelatin, their derivatives and alginates; polyacrylic resins; polyvinyl alcohol; polyethylene oxide; polyvinylpyrrolidone (PVP) or polyvinyl ethers, copolymers and derivatives thereof; cellulose derivatives; thermoplastic elastomers of block polymers and preferably styrene block copolymers and more preferably the hydrogenated classes styrene / ethylene-butylene / styrene (SEBS), styrene / isoprene / styrene (SIS) and styrene / ethylene-propylene / styrene (SEPS);

- from 51 to 99.5% by weight of the plasticizer or the plasticizer mixture, which are liquid at room temperature. Non-limiting examples of a softening composition 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 May be water, various alcohols (such as glycerol in particular), glycols, polyglycols, liquid polybutenes (or polybutylenes), natural or synthetic oils such as vegetable oils, mineral oils or combinations thereof;

- from 0 to 600% by weight of macromolecules! polymeric tack-enhancing resins, the main application of which is to adapt Tg especially in systems based on synthetic polymers;

From 0.5 to 10%, and more preferably from 0 to 5%, by weight of the substance to facilitate and stabilize the gelling of both hydrophilic and hydrophobic emollients. These may be for oil systems, for example, C ₈ to C ₂ fatty acids, their metal salts and their polyoxo derivatives; lanolin derivatives; silicon dioxide; bentonite, montmorillonite and derivatives thereof; polyamides, waxes and mixtures thereof.

Conventional additives known in the art, such as preservatives, antioxidants, anti-UV agents, colorants, mineral fillers, rheology modifiers, etc., which may also be included in amounts up to 10% each.

When chemical cross-links are formed in a given system, the cross-linker may preferably be present in amounts up to 5% by weight. Chemical crosslinking can also be formed by neutralizing polymers having different functionalities as in the reaction between acidic polyacrylic resins and polysaccharides by mutual neutralization.

The resulting body adhesive compositions can be divided into three groups according to the nature of the main component, i.e., the liquid softener composition (s):

• · · · ·

• · ♦ * ft

1) Hydrophobic compositions in which the emollient is typically an oil or a mixture of oils of vegetable or mineral origin and the polymer is usually a synthetic polymer, preferably an elastomer, soluble or swollen in the oil (s).

2) Mixed phase compositions in which both the hydrophobic and hydrophilic components, optionally both in the emollients and in the polymers, form two or more separate phases. In such cases, an emulsifier / active surfactant is preferably present at an appropriate level to form stable emulsions between said incompatible phases. It is preferred for the body-facing adhesives of the present invention that the hydrophobic components predominate over the hydrophilic components.

3) Hydrophilic compositions in which the plasticizer is typically water / glycerol / glycols and the like and / or mixtures thereof and the polymer phase is of synthetic (e.g., polyacrylic resin) or natural (e.g., natural gum) origin or mixtures thereof.

It will be appreciated that, contrary to what is already known in the medical art and the prior art cited, hydrophilic compositions (mixtures) are not preferred, while mixtures of hydrophobic and mixed phases 1 and 2) are preferred in the applications of the present invention.

This depends in part on technical reasons in the sense that many hydrophilic compositions used in the medical field exhibit too low elastic character and cohesion to be useful in the present invention. The second reason for giving preference to hydrophobic mixtures or mixed φφφφ •φφφφφφφφ

The phase is that the application of the present invention particularly in the field of hygienic contacting for absorption.

The liners will include the likelihood of fluid-to-body adhesive Since these absorbent fluids are all generally of aqueous type, contact with the hydrophilic body-adhesive would result in some absorption of body fluids into body-to-body adhesives.

This would then result in a change in the rheological characteristic and hence the appropriate functionality of the body-facing adhesive, giving an unhygienic appearance, but also causing the body fluids to remain in direct contact with the skin for an extended period of time, which is typically undesirable disposable absorbent articles. In addition, this may also create a potential unpleasant impact for the user, since some hydrophilic compositions are a potentially good cultural environment for the growth of many microorganisms containing even the pathogenic ones.

Another hydrophilic body adhesive also tends to be perceived as cold and wet, so that the use of a fresh sanitary napkin or underarm sweat pad is not in accordance with the typical consumer expectations. The additional problems result from the fact that in particular, body-facing adhesives containing water as a softening agent tend to dry out when not enclosed in an impermeable package.

The absorbent articles of the present invention can be manufactured by any of the methods known in the art. Applying adhesive to the topsheet side of the absorbent article should not cause greater problems to those skilled in the art, as this can be accomplished by techniques similar to those commonly used for adhesive fastening panties. The total area facing the wearer facing surface of the absorbent article that is covered

9999

999 · • 9 · 9 · 9 · 9 ·

9 99 99 9 9 9

998 99 9 · «····

999999 9 9 • 99999 9 · · 9 · 99 adhesive for application to the body should not be more than 20%, preferably not more than 10%. The adhesive is preferably near the periphery of the absorbent article, and in the case of the film topsheets (or when the backsheet is folded over the topsheet), the adhesive is preferably on a non-liquid-permeable portion of the film.

The body adhesive on the article (as is common with pantie fastening adhesives) needs to be protected from use. This protection can be provided by a release liner such as a siliconized or surfactant-treated paper, provided that the paper is a good release surface for a specifically selected body adhesive.

In principle, the absorbent article of the invention is supported on the body of the wearer by an adhesive for adhering to the body and does not require additional support to remain in place. However, it is possible, for example, to provide a sanitary napkin with a slip resistant coating on the side of the backsheet, in order to prevent the sanitary napkin from progressively moving out of its location. Also, although pantie fastening adhesives are not desirable and are therefore not preferred according to the present invention, they are not strictly excluded in the context of the present invention.

EXAMPLE 1

The oil based composition useful in the present invention was formulated using 9.9% by weight of Kraton G-1651; a styrene / ethylene-butylene / styrene block copolymer containing 33% by weight of styrene is available from Shell Co .; and 59.3% by weight of Kaydol, a paraffinic mineral oil available from Witco Co.

· 999 ·

9 99 99

9 9 9

999 999

In addition, the blend contained 301 parts of tackiness of the increasing resin per 100 parts of Kraton polymer. The tackifying resin was Escorez 5300, a hydrogenated resin available from Exxon Co.

Magnesium stearate, available from Carlo Erba S.p.A, was used as a cogelifying agent for the oil at 0.7% by weight.

Ciba-Geigy antioxidant, Irganox 1010 was added at 0.3% by weight.

So in the end it has this content:

composition following percentage

Kraton G-1651 9, 9% weight, Kaydol 59, 3% weight, Escorez 5300 29.8% weight, Magnesium stearate 0.7% weight, Irganox 1010 0.3% weight.

This composition exhibited the following rheological properties at 37 ° C.

a) Modulus of elasticity at 1 rad / sec, 6 ^Σ 37 = 6 876 Pa.

(b) Ratio between modulus of elasticity and modulus of viscosity at 1 rad / sec, G ^x 37 / G ^ir 37 = 12,49,

Ratio between modulus of elasticity and modulus of viscosity at 100 rad / sec, G ^T 37 / G ^{I: E} 37 = 7.01.

c) Ratio G ^T 37 at 100 rad / sec. G ^T 37 at 1 rad / sec. was 1,308.

The above composition has been judged comfortable for application to sensitive, hairy skin.

«9 9 9

9 9 9

9

9

999 99 99

999 99 99

9 · · ·

9

9 999999

9 9

9

COMPARATIVE EXAMPLE

The compound oil-based mixture was formulated using 7.1% by weight of Kraton G-1651; styrene / ethylene-butylene / styrene block copolymers containing 33% by weight of styrene and available from Shell Co .; and 41.9% by weight of Kaydol, a paraffin mineral oil available from Witco Co.

In addition, the blend contained 704 parts of tack-increasing resin per 100 parts of Kraton polymer. The tackifying resin was Regalrez 3102, a hydrocarbon resin available from Hercules Co.

Magnesium stearate, available from Carlo Erba S.p.A, was used as a cogelifying agent for the oil at 0.7% by weight.

An antioxidant from Ciba-Geigy, Irganox 1010 was added at 0.3 weight percent.

So in the end this composition has the following percentage:

Kraton 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.

This composition exhibited the following rheological properties at 37 ° C.

a) Modulus of elasticity at 1 rad / sec, G ^I 37 = 3 059 Pa.

b) Ratio between modulus of elasticity and modulus of viscosity at 1 rad / sec, G ^x 37 / G ^XI 37 = 2.53, • 9,999 · ····

9 9

9

9

9 9

9999 99

**

9 9 • 9

99> 999

9

99

Ratio between modulus of elasticity and modulus of viscosity at 100 rad / sec, G ^r 37 / G ^IX 37 = 0.74.

c) Ratio 6 ³ 37 at 100 rad / sec. G ^T 37 at 1 rad / sec. was 4,944.

The above composition has been judged to be very inconvenient for application to the skin of the forearm. Use on sensitive skin with hair was unacceptable.

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Claims (10)

PATENT CLAIMS A disposable absorbent article for external adherence to a wearer having a wearer facing surface and a garment facing surface, and comprising an absorbent core between the wearer facing surface and the garment facing surface; characterized in that the article comprises at least a portion of the wearer facing surface of an adhesive for external adhesive attachment of the article, said adhesive having a modulus of elasticity at 37 ° C (100 ° Fahrenheit), 6 ^Σ 37, and a viscosity modulus at 37 ° C (100 ° Fahrenheit), ^G13: 37, this adhesive is selected to have a dynamic elastic behavior such that the difference -G ^I 37, from G ^T 37 at a applied load frequency of 1 rad / sec. and G ^I 37 at an applied load frequency of 100 rad / sec, not more than 150% of G ^r 37 at an applied load frequency of 1 rad / sec, preferably not more than 10,000 Pa, and the adhesive is selected to have dynamic viscous behavior such that the difference -G ^{I: I} 37, from G ^II 37 at a applied load frequency of 1 rad / sec. and G ^II 37 at a applied load frequency of 100 rad / sec, is not more than 10,000 Pa, preferably not more than 5,000 Pa. Product according to claim 1, characterized in that the value of the ratio G ^I 37 over G ^TI 37, in the frequency range of the applied loads from 1-100 rad / sec, is greater than or equal to 1, preferably greater than or equal to 1, 6 and most preferably greater than or equal to 3.3. ··· 99 * 9 9999 • 9 9 9 9 9 9 9 9999 98 99 98 99 «9 9 9 9 9 9 9 999999 9 9 9 9 Product according to claim 2, characterized in that the value of the ratio G ^x 37 over G ^IT 37 varies with increasing frequency of applied loads for at least the applied frequency range from 1-100 rad / sec, and this change G ¹ over G ¹¹ is a factor of 3 or less, preferably 2 or less. Product according to any one of the preceding claims, characterized in that at a frequency of applied loads of 1 rad / sec. the G ^T 37 value is less than 20,000 Pa, preferably less than 15,000 Pa, and most preferably less than 10,000 Pa. Product according to any one of the preceding claims, characterized in that at a frequency of applied loads of 1 rad / sec. the G ^IT 37 value is less than 15,000 Pa, preferably less than 10,000 Pa, and most preferably less than 5,000 Pa. 6. The article of any of the preceding claims, wherein said adhesive is a mixture of materials comprising: from 51% to 99.5% by weight of a softening compound or mixture which is liquid at 20 ° C; from 0.5 to 20% by weight of a polymer compound or mixture that is soluble or swellable in said softening compound or mixture; attaching with an increasing resin in an amount of from 0% to 600% by weight of said polymer compound or mixture. 7. The article of claim 6, wherein: Said softening compound or mixture is selected from the group consisting of water, alcohols, glycols, oil, or a combination thereof, and said polymeric compound. or the mixture is selected from the group consisting of block copolymer thermoplastic elastomers, styrene block copolymers and hydrogenated styrene block copolymers. An article according to any one of the preceding claims, characterized in that said adhesive is at least partially hydrophobic, preferably 80% by weight of said adhesive consists of hydrophobic components and most preferably all components of said adhesive are hydrophobic. An article according to any of the preceding claims, wherein said adhesive covers less than 20%, preferably less than 10%, of the surface facing the wearer of the absorbent article. The article of any of the preceding claims, which is a sanitary napkin or panty cover.