WO2024251696A1

WO2024251696A1 - Absorbent hygiene article with skin-care composition

Info

Publication number: WO2024251696A1
Application number: PCT/EP2024/065258
Authority: WO
Inventors: Frida RYTTSÉN; Ulrika Husmark; Katarina ZOREVAND; Sofia LAFQVIST; Anna KARLGREN; Clementine MARECHAUD; Serena DEL BELLO
Original assignee: Essity Hygiene And Health Aktiebolag
Priority date: 2023-06-07
Filing date: 2024-06-04
Publication date: 2024-12-12

Abstract

The present disclosure relates to an absorbent hygiene article comprising a liquid permeable topsheet and an absorbent core, wherein the topsheet is provided with a skin-care composition on at least the side of the topsheet facing a user when the absorbent hygiene article is worn by a user. The skin-care composition is a dry coating comprising gluconic acid and a water miscible vehicle, such as glycerine, propylene glycol and/or PEG. The absorbent hygiene article may be a diaper, incontinence shield, sanitary napkin, panty liner, tampon or wound dressing.

Description

ABSORBENT HYGIENE ARTICLE WITH SKIN-CARE COMPOSITION

TECHNICAL FIELD

The disclosure relates to an absorbent hygiene article comprising a fluid- permeable topsheet and an absorbent body wherein a skin-care composition is provided on at least the side of the fluid-permeable topsheet facing the user when the absorbent hygiene article is worn by the user.

BACKGROUND

Absorbent hygiene articles of the kind to which this disclosure relates, e.g. diapers for children as well as for adults, incontinence shields, sanitary napkins and panty liners, tampons or wound dressings are adapted to be worn against the skin of a user with the purpose of absorbing body exudates such as urine, faeces, liquid discharge, menstrual fluid, or wound exudate comprising liquid leaking out of blood vessels and may contain serum, fibrin and leukocytes. Such absorbent hygiene articles conventionally comprise a liquid permeable topsheet layer, an absorbent core and a backsheet layer.

Uses of products that are applied in direct contact with the skin may lead to unwanted side-effects. These may occur because of occlusion, moisture, mechanical, microbial, and enzymatic factors which all, to different degrees, interact and amplify the influence of each other and may cause different forms of skin irritation and primary or secondary skin infections which sometimes occur in users of said articles. An increase in pH is a normal phenomenon during use of for example sanitary articles in contact with skin. It has been demonstrated that skin with pH values below 5.0 is in a better condition than skin with pH values above 5.0. This has been shown by measuring the biophysical parameters of barrier function, moisturization and scaling. The effect of pH on adhesion of resident skin microflora has also been assessed and it has been shown that an acid skin pH (4-4.5) keeps the resident bacterial flora attached to the skin, whereas an alkaline pH (8-9) promotes the dispersal from the skin, see e.g. Lambers H et al (2006), Natural skin surface pH is on average below 5, which is beneficial for its resident flora. Int J Cosmet Sci, 28 (5), 359-70.

Another example of unwanted effects of using absorbent hygiene articles in contact with the skin is the increased activity of enzymes such as lipases and proteases which exhibit a strongly pH-dependent activity which increases with increasing pH. With the increased enzyme activity, the skin starts to decompose and becomes sensitive to mechanical forces and bacterial attacks.

Absorbent hygiene articles comprising acidifying agents incorporated to control the pH of the skin in contact with the absorbent hygiene article are generally known in the art. The acidifying agents may be applied in lotions or in aqueous solutions.

Application of the acidifying agent in an aqueous form may have less impact on the absorbency of the absorbent hygiene article. However, there are also other aspects to take into account in terms of efficacy of the added agent during the use of an absorbent hygiene article, a simple and well-functioning application process as well as ensuring a long shelf life, i.e. storage stability.

There is therefore still a need in the art for improved absorbent hygiene articles exhibiting improved skin-care properties.

SUMMARY

The present disclosure relates to an absorbent hygiene article having improved skin-care properties. The absorbent hygiene article comprising a topsheet provided with a skin-care composition, which skin-care composition is intended to be transferred, during use, to the skin tissues or mucous membranes of the user.

According to one aspect, the present disclosure relates to an absorbent hygiene article comprising a liquid permeable topsheet and an absorbent core, wherein the topsheet is provided with a skin-care composition on at least the side of the topsheet facing away from the absorbent core. The skincare composition is a dry coating comprising gluconic acid and a water miscible vehicle, such as glycerine, propylene glycol and/or PEG.

According to one aspect, the present disclosure relates to an absorbent hygiene article comprising a liquid permeable topsheet, a backsheet and an absorbent core disposed between the topsheet and the backsheet, wherein the topsheet is provided with a skin-care composition on at least the side of the topsheet facing away from the absorbent core. The skin-care composition is a dry coating comprising gluconic acid and a water miscible vehicle, such as glycerine, propylene glycol and/or PEG.

According to one aspect, the present disclosure relates to an absorbent hygiene article, wherein the liquid permeable topsheet and the absorbent core is an integrated structure, comprising either a laminate, or only one layer having both a liquid permeable function and a liquid absorbing function.

In presence of water, lactone exists in an equilibrium between the lactone form and its corresponding hydroxycarboxylic acid form, thereby providing a pH adjusting effect. Hereinafter, the term “gluconic acid” refers to the equilibrium system of the gluconic acid and its corresponding lactone. The equilibrium system between gluconic acid and its corresponding lactone may be obtained by mixing either gluconic acid or gluconolactone in water, or by mixing both gluconic acid and gluconolactone in water.

The skin-care composition water miscible vehicle, such as glycerine, propylene glycol and/or PEG may be provided on the topsheet in an amount within the range of from 0.04 to 9.0 g/m², as measured over the area being coated.

The gluconic acid may be provided on the topsheet in an amount within the range of from 0.01 to 4.0 g/m², as measured over the area being coated. The dry coating may be provided on the topsheet in an amount within the range of from 0.2 to 10.0 g/m², optionally within the range of from 0.2 to 5.0 g/m² as measured over the area being coated.

According to one aspect, the water miscible vehicle is glycerine. Upon transfer of the skin-care composition to the user's skin, the high weight-% glycerine in the dry coating may have a moisturizing effect on the user. As a result of the moisturizing property, the glycerine will counteract the negative effects which arise in connection with the dehydration of skin tissues and mucous membranes.

Furthermore, it has been discovered that the transfer of gluconic acid to the skin of the user is significantly higher with a skin-care composition comprising glycerine compared to a skin-care composition comprising gluconic acid but without glycerine. The improved transfer of gluconic acid to the skin is also beneficial since the pH is more effectively decreased. This is beneficial for different absorbent hygiene products aiming for keeping or improving a diverse and healthy skin microflora.

The water activity value in the dry coating may be lower than 0.7, or optionally lower than 0.6. Since the water activity of the dry coating is low, development of microorganisms may be suppressed.

The skin-care composition may be free from preservatives. For a skin-care composition without a water miscible vehicle, such as glycerine, propylene glycol and/or PEG, the water activity may be higher and would be needed to be preserved if it should be storage stable before it is provided on the topsheet layer and dried. Preservatives are known for being able to decrease activity of also beneficial skin bacteria and may negatively impact the diversity and richness of skin microflora. Therefore, it is beneficial with a skincare composition without preservatives. Examples of preservatives are sodium benzoate, potassium sorbate, phenoxyethanol, chlorphenesin and dehydroacetic acid. The gluconic acid is obtained from the group consisting of y- and/or 5- lactones. A dry coating comprising gluconic acid on the topsheet has shown to maintain a low pH more stable than a corresponding dry coating of lactic acid.

In another aspect, the present disclosure relates to a method for the manufacture of an absorbent hygiene article comprising disposing an absorbent core between a liquid permeable topsheet and a backsheet, wherein the topsheet is provided with a skin-care composition on at least the side of the topsheet facing away from the absorbent core. The skin-care composition is a dry coating comprising gluconic acid and a water miscible vehicle, such as glycerine, propylene glycol and/or PEG.

In yet another aspect, the present disclosure relates to the use of an absorbent hygiene article to adjust or maintain the pH of the skin in contact with the article to a value of from 3.5 to 5.5.

These and other aspects of the invention will be further explained below.

DETAILED DESCRIPTION

In a first aspect, the present disclosure relates to an absorbent hygiene article, comprising a liquid permeable topsheet, a backsheet and an absorbent core disposed between the topsheet and the backsheet. The article defines a bodyfacing side, intended to be placed against or towards the skin of the wearer, and an opposite, garment facing side, with the topsheet being the outermost layer at the bodyfacing side. According to one embodiment is the absorbent hygiene article a thin absorbent liner comprising a liquid permeable topsheet and a backsheet, but not a separate absorbent core layer. According to this embodiment, the liquid permeable topsheet functions as both the topsheet as well as the absorbent core.

In the article, the topsheet is provided with a skin-care composition on at least the side of the topsheet facing away from the absorbent core, which is the side facing a user when the absorbent hygiene article is worn by a user. The skin-care composition is a dry coating comprising a water miscible vehicle, such as glycerine, propylene glycol and/or PEG, and furthermore comprising gluconic acid.

As used herein, the term “dry coating” refers to a coating being formed on a material by application of a composition being applied to a web material in a liquid carrier being liquid in room temperature, such as an aqueous solution, followed by drying of the web material, thereby resulting in a dry coating formed on the web material. A “dry” coating, as referred to herein, relates to a coating that has a water content not significantly exceeding the level of water being inevitable due to an equilibrium between the coating and the surrounding atmosphere.

When the skin-care composition is provided on the topsheet material, it is at least present on the side of the topsheet facing away from the absorbent core, i.e. the wearer facing side of the topsheet. The skin-care composition may also be provided on the side of the topsheet facing the absorbent core, i.e. the garment facing side of the topsheet. When the topsheet material is a fibrous material, e.g. a nonwoven, the dry coating may essentially be as a layer around the at least part of the circumference of the indvidual fibres.

The gluconic acid may be obtained from the group consisting of y- and 5- lactones i.e. lactones with 5- or 6-membered rings. A function of the gluconic acid in the dry coating according to the present disclosure is to maintain natural skin pH or to adjust the pH to a beneficial value and thus being beneficial for intimate skin health. This may be achieved by use of an absorbent hygiene article in accordance with the present disclosure since the gluconic acid thereof is coated onto the topsheet which is the material layer being in direct contact with the skin of the user and therefore may contribute to a suitable pH on the topsheet.

In presence of water, the lactone exists in an equilibrium between the lactone form and its corresponding hydroxycarboxylic acid form, thereby providing a pH adjusting effect. Hereinafter, the term “gluconic acid” refers to the equilibrium system of the gluconic acid and its corresponding lactone. The equilibrium system between gluconic acid and its corresponding lactone may be obtained by mixing either gluconic acid or gluconolactone in water, or by mixing both gluconic acid and gluconolactone in water.

It is believed that the transfer of the lactone or corresponding hydroxycarboxylic acid thereof may occur both as dry transfer from the coating being in contact with the skin and as wet transfer by means of the bodily fluids being in contact with the coating and also with the skin and the environment between the topsheet and the user skin.

The term gluconic acid refers to the equilibrium system of the compound in the lactone ring form and the hydroxycarboxylic form. While lactones may exist in different stereoisomeric forms, for the purposes of the present disclosure, all isomeric forms of lactones are considered to be included under this term. The currently preferred lactone for use in accordance with the present invention is gluconolactone, specifically D-glucono-b-lactone, which is formed by intramolecular esterification of gluconic acid. The at least one lactone may therefore be, or to a major portion comprise, gluconolactone, e.g. D-glucono-b-lactone.

In addition to the water miscible vehicle and the gluconic acid, the dry coating composition may further comprise a surfactant. A surfactant according to the present disclosure is a substance which lowers the surface tension of the medium in which it is dissolved, and/or the interfacial tension with other phases, and, accordingly, is positively adsorbed at the liquid/solid and/or at other interfaces. The surfactant may be any known surface active agent suitable for use in hygienic applications, as is generally known in the art, suitable surface active agents may include any cationic surfactant, anionic surfactant, nonionic surfactant, zwitterionic surfactant or surfactant of amine oxide type suitable for use in hygienic applications and should lower the surface tension of the aqueous solution to allow the solution to spread more easily over the topsheet. This is especially relevant for topsheet materials comprising a high amount of or entirely consisting of synthetic fibers and thus being mainly hydrophobic. A hydrophobic topsheet material may also be preferred due to the reduced wetting zone after wetting of the topsheet.

Examples on suitable surface active agents are; Silastol PHP26, Silastol PHP 28, Silastol PHP 163, Silastol PHP 207 (Schill & Seilacher GmbH), Stantex S 6327 (Cognis), Duron OS 1547, Duron OF 4012 (CHT/BEZEMA), Nuwet 237* and Nuwet 550 (Momentive).

The surfactant may be added to the topsheet at a concentration sufficient for it to exhibit the desired effect, and may for example be up to 1 wt%, such as from 0.1 to 0.8 wt% based on the weight of the untreated weight of the topsheet, i.e. before application of the dry coating.

The skin-care composition may be free from oil and emulsifier.

The dry coating may be essentially homogenously applied on the topsheet, or may be applied in a patterned manner, covering only part of the surface of the layer on which it is applied.

When applied in a patterned manner, the dry coating may for example cover at least 10 area-%, such as from 10 to 90 area-% of the layer on which the coating is applied. For example, the dry coating may be applied regionally to parts of the topsheet that is intended to be in contact with skin especially benefited from the pH-lowering and the moisturizing effect in the coating.

As used herein, the term "absorbent hygiene article" refers to products that are intended to be placed against the skin of the wearer to absorb and contain body exudates, such as urine, faeces, menstrual fluid, or wound exudate comprising liquid leaking out of blood vessels and may contain serum, fibrin and leukocytes. Examples of absorbent hygiene articles include feminine hygiene products such as sanitary napkins, panty liners, sanitary panties and feminine inserts; diapers and pant diapers for infants and incontinent adults; incontinence pads; diaper inserts and the like, as well as tampons and wound dressings. The liquid permeable topsheet can be any suitable topsheet material as known by the person skilled in the art and may be fibrous topsheet material composed of a nonwoven material, e.g spunbonded, meltblown, carded, hydroentangled, wetlaid, etc. Suitable nonwoven materials can be composed of natural fibers, such as woodpulp or cotton fibres, synthetic thermoplastic fibers, such as polyolefins, polyesters, polyamides and blends and combinations thereof or from a mixture of natural and synthetic fibers. The topsheet material may essentially constitute of non-absorbent fibers, such as synthetic thermoplastic fibers, such as such as polyolefins, polyesters, polyamides and blends and combinations thereof. The synthetic fibers may be monocomponent fibers, bicomponent fibers or multicomponent fibers comprising polyesters, polyamides and/or polyolefins such as polypropylene and polyethylene. It is contemplated that a nonwoven material used as a topsheet in accordance with the present disclosure may be a single layer or multilayered material. Examples of the latter including for example combinations of spunbonded and meltblown fibres, commonly referred to as SMS (spunbond-meltblown-spunbond), SMMS (spunbond-meltblown- meltblown-spunbond) as well as other multilayered nonwoven materials.

The topsheet material may alternatively be a perforated plastic film, i.e. a plastic film provided with a plurality of openings or holes allowing liquid to pass from one side of the film to the other side of the film through the openings. Further examples of topsheet materials are porous foams.

The materials suited as topsheet materials should be soft and non-irritating to the skin and be readily penetrated by body fluid, such as urine or menstrual fluid.

The topsheet may have a dry basis weight of from 10, such as from 15, to 50, such as to 30, for example to 25 g/m².

The backsheet may consist of a thin plastic film, e.g. a polyethylene or polypropylene film, or a nonwoven material coated with a liquid impervious material, a hydrophobic nonwoven material, which resists liquid penetration. Laminates of plastic films and nonwoven materials may also be used. The backsheet material is preferably vapour permeable, breathable, so as to allow vapor to escape from the absorbent structure, while still preventing liquids from passing through the backsheet material, i.e. being liquid impermeable and vapour permeable.

The absorbent hygiene article according to this disclosure comprises an absorbent structure, the absorbent core, arranged between the topsheet and the backsheet. The absorbent core can be of any conventional kind.

Examples of commonly occurring absorbent materials are cellulosic fluff pulp, tissue layers, highly absorbent polymers (so called superabsorbents), absorbent foam materials, absorbent nonwoven materials or the like. It is common to combine cellulosic fluff pulp with superabsorbents in an absorbent structure. It is also common to have absorbent structures comprising layers of different material with different properties with respect to liquid acquisition capacity, liquid distribution capacity and storage capacity. This is well-known to the person skilled in the art and does therefore not have to be described in detail. The thin absorbent bodies, which are common in today's sanitary articles, often comprise a compressed mixed or layered structure of cellulosic fluff pulp and superabsorbent. For the purpose of the present disclosure, the term “absorbent core” in its broadest meaning also include liquid retaining structures which retains liquid by means of capillary forces, such as open cell porous structures, such as foams, and high loft materials of synthetic fibres.

Absorbent cores for use in absorbent products in accordance with the present disclosure may comprise superabsorbent polymers or may essentially or completely be free from superabsorbent polymers. If superabsorbent polymers are present, such may be present at an amount of example from 10, such as from 25, for example from 40, to 100, such as to 80, for example to 75 wt% superabsorbents, based on the total weight of the absorbent core. The size and absorbent capacity of the absorbent core may be varied to be suited for different uses such as sanitary napkins, pantyliners, adult incontinence pads and diapers, baby diapers, pant diapers, etc.

The hygiene absorbent article in accordance with the present disclosure may comprise further layers in addition to the topsheet, backsheet and absorbent core, as is well known in the art. For example, a liquid permeable and nonabsorbing layer, herein also referred to as an “intermediate layer” may be disposed between the absorbent core and the topsheet, over at least part of the bodyfacing surface of the absorbent core. An intermediate layer may be a porous fibrous layer, such as a nonwoven material, essentially consisting of non-absorbent fibers, and may be referred to as an acquisition layer. The basis weight of the intermediate layer may be between at least 20 g/m², such as at least 40 g/m², such as from 40 g/m² to 150 g/m², such as from 40 g/m² to 100 g/m².

The term “non-absorbent fibers” refers to fibers which do not absorb water to an appreciable extent. Suitable polymers from which the non-absorbent fibers may be formed are non-water-absorbent polymers such as polyolefins, polyesters, polyamides and blends and combinations thereof. The non- absorbent fibers may be monocomponent fibers, bicomponent fibers or multicomponent fibers comprising polyolefins, polyesters, polyamides and blends and combinations thereof.

The present disclosure also relates to a method for the production of an absorbent hygiene article as defined herein. Methods for production of an absorbent product in general will vary between different types of absorbent products and are generally known to those skilled in the art. Generally, such a method comprises the step of bonding together a liquid permeable topsheet and an absorbent core wherein the topsheet is provided with a dry coating comprising gluconic acid, and a water miscible vehicle, such as glycerine, propylene glycol and/or PEG. The topsheet layer provided with the dry coating may be produced by providing a liquid permeable web material; applying a liquid composition comprising the water miscible vehicle, such as glycerine, propylene glycol and/or PEG, and gluconic acid to the web material and thereafter drying the liquid composition applied to the web material in order to obtain a dry coating on the web material.

The skin-care composition may be applied to the web material by any suitable means, including spraying, slot coating, kiss roll coating and/or soaking the material in a bath containing the coating composition, as well as by printing the composition onto the web material by contact or non-contact printing methods known to the person skilled in the art. The coating may be performed in-line during assembly of the absorbent hygiene article. Alternatively, the topsheet material may be prepared separately and delivered as ready-to-use rolls to the absorbent hygiene article manufacturing plant. The coating may also be formed by a combination of the above methods.

When the dry coating contains further components besides the at least one water-miscible vehicle and the gluconic acid, such as for example a surfactant, each component may be added to the web material in a single coating step, or may be applied in separate steps to the web material. For example, the web material may be pretreated with surfactant before the application of the gluconic acid, or the gluconic acid may be applied simultaneously with the surfactant.

Benefits of absorbent hygiene articles in accordance with the present disclosure will now be described with reference to the following non-limiting examples. EXAMPLES

Measurement on skin-care composition

Used skin-care compositions are shown in table 1.

Table 1

Water activity measurement

Water activity of the skin-care compositions, glycerine and gluconic acid were measured using an instrument from Aqua Lab, Dew Point Water Activity Meter 4TE and the measurements were performed in room temperature (22 °C).

Results from the water activity measurements are shown below in table 2a and Table 2b. Table 2a

From the results above, it is apparent that the skin-care composition with glycerine has a lower water activity than the water-based skin-care composition without glycerin. Water activity was below 0.6 in the skin-care composition with glycerine and therefore preservatives are not needed for the skin-care composition with glycerin. For the skin-care composition without glycerine the water activity is higher, and it must be preserved if it should be storage stable before application and drying onto nonwoven. Preservatives are known for being able to decrease activity of also beneficial skin bacteria and may negatively impact the diversity and richness of skin microflora. Therefore, it is beneficial with a skin-care composition without preservatives. So, since the skin-care composition contains glycerine, the water activity value can be kept low, while sufficient surface moisture percentage is ensured, and even in the absence of a preservative, development of microorganisms can be suppressed to provide improved shelf life.

The result in table 2b shows water activity of gluconic acid, glycerine and compositions with both gluconic acid and glycerine. Table 2b

pH measurement pH was measured on the skin-care compositions before roll coating. pH of the skin-care compositions was measured using Orion Star A211 from Thermo Scientific.

Results from the pH measurements on the skin-care composition are shown below in table 3. Table 3

From the results above, it is shown that the skin-care composition with glycerine has a pH higher than the skin-care composition without glycerin.

Measurement on nonwoven with skin-care composition pH was also measured on the nonwoven materials after the nonwoven materials had been dried in room temperature. pH on the nonwoven samples was measured using Orion Star A211 from Thermo Scientific with a flat electrode. Nonwoven samples having a diameter of 36mm was punched out, folded twice and 50pL 0.9% NaCI was added. Three samples were measured and the mean value is shown below in table 4. Table 4

From the result above, it is shown that the nonwoven with skin-care composition with glycerine and the nonwoven with skin-care composition without glycerine have almost equal pH-values. Transfer to skin measurement

A short transfer to skin measurement and a longer transfer to skin measurement were performed. The short measurement was 1 minute and the longer measurement was 4 hours. In both measurements four volunteers were tested on the volar side of the arm. In the transfer to skin measurements the nonwoven materials have been roll- coated with two different skin-care compositions, skin-care composition with glycerine (A) and skin-care composition with water (B).

Skin-care composition with glycerine(A) and skin-care composition with water (B) were “roll-coated” in laboratory scale (K-Lox, Innova Nordic AB, roll 180/14) onto the nonwoven material Berry Global J1704122, 15. GSM, #81715171. The roll-coater is a small device that will distribute the liquids evenly over the nonwoven surface. All test samples were roll-coated, either with skin-care composition with glycerine (A) or with skin-care composition without glycerine (B). The skin-care composition without glycerine was waterbased.

After drying in room temperature, the amounts of gluconic acid on the two different nonwoven materials were quantified using LC-MS/MS. To be able to measure the amount of gluconic acid on the nonwoven or on the tape strips from skin in the transfer to skin measurement (in table 5 below), the nonwoven samples (26 mm diameter) and the tape strips (22 mm diameter) were extracted in 0.1 % ammonia in water and gluconic acid was separated on a HSS T3 C18 Column (Waters). Gradient elution was delivered by an Agilent 1290 Infinity II using 0.1 % formic acid in water to 0.1 % formic acid in acetonitrile. The effluent was detected on a 6470 triple quadrupole LC- MS/MS, measuring with electrospray ionization in negative mode and the data was recorded with Masshunter Workstation Software (Agilent Technologies). The use of calibration curve of gluconic acid and an internal standard (Gluconic acid-d6) enabled quantification. Dilution factors and area of the samples were accounted for.

The amount of gluconic acid on the nonwoven surface was measured after the skin-care composition was provided on the nonwoven, and after the drying step. The value in the table is the mean value of nine samples (replicates). Table 5 shows the amount of gluconic acid on the nonwoven materials with the skin-care compositions A and B.

Table 5

The result in table 5 shows that the amount of gluconic acid was lower on the nonwoven with skin-care composition comprising glycerine (A) than on the nonwoven with skin-care composition without glycerine (B).

In the short transfer measurement, the test person was exposed to the nonwoven sample for one minute, while applying a 1 kg weight on top of the nonwoven sample. After removal of the weight and the nonwoven sample, the outermost layer of the skin was harvested with a tape strip and the amount of gluconic acid was quantified. Three tape strips on each person were measured and the mean value of the amount of gluconic acid is shown in the table 6.

Table 6

Table 6 shows the result from the gluconic acid transfer measurement in the short test. As is clearly shown, the amount of gluconic acid transferred to the skin is much higher with the skin-care composition A comprising glycerin, than with the skin-care composition B without glycerin. So, the short test showed that the combination of glycerine and gluconic acid was preferred.

Furthermore, despite that the initial amount of gluconic acid was lower on the sample with glycerine and gluconic acid, comparing to the sample with water and gluconic acid (see table 5), the transfer of gluconic acid was significantly higher in combination with glycerin.

In the longer transfer test, the test persons were wearing the nonwoven samples for 4 hours. The size of the nonwoven samples were 5 x 8 cm and the nonwoven material was fixated with Fixomull adhesive from BSN. The test persons were allowed to move around as usual but after four hours they came back to the laboratory. In this case the skin pH was measured after removal of the nonwoven materials. pH was measured on the skin close to the covered areas after removal from the area that had been covered by the samples. pH was also measured on the uncovered area directly beside the covered area as reference (Ref A and Ref B) to compare with respective areas covered by nonwoven samples with skin-care compositions. Ref A was measured close to the area covered by the nonwoven with glycerine and gluconic acid, and Ref B was measured close to the area covered by nonwoven with water and gluconic acid. Results from the pH measurements on skin are shown below in the table 7.

Table 7

In the longer transfer to skin measurement, as can be seen in Table 7, it was concluded that pH on skin was more efficiently decreased after wearing the nonwoven sample with glycerine and gluconic acid, than after wearing the nonwoven sample with a water-based composition with gluconic acid without glycerin.

Bacterial growth measurement

In this example it was measured how treated nonwoven, with the combination of glycerine and gluconic acid, was able to influence the balance of beneficial versus unwanted bacteria. E.coli (ATCC 10536) and S. aureus (ATCC 6538) was selected as representants for unwanted bacteria, one gram-negative and one gram-positive. Lplantarum (LB931 , clinical isolat) was used as the representative of a beneficial group of bacteria, Lactobacillus.

A pilot scale flexo-printer (Anilox 10) was used for the application of a dry coating containing gluconic acid and glycerine onto the nonwoven. The dry coating also contained NaOH for balancing pH to 3.4. Tinopal was added as a fluorescent additive to be able to visually, in UV light, inspect the treated nonwoven and secure even printing. Ingredients in the skin-care composition in the bacterial growth measurement is shown in table 8.

Table 8

A thin agar was molded containing 1 % nutrient broth. The nutrient was added to more resemble the situation on skin. The three test bacteria were seeded out onto three different agar surfaces and the initial concentration of the liquid was approx. Log 4 cfu/ml. The agar surface diameter was 9 cm. A circle of the treated nonwoven and the reference nonwoven (diameter 2,5 cm) was applied, covering and in close contact with the bacteria seeded out on the agar surface and incubated 35 °C 137 °C overnight. The next day the bacteria under the test samples was counted. The number of bacteria per square cm, Log cfu/cm² can be seen in table9.

The start value is the number of bacteria before the incubation. The reference nonwoven is the nonwoven without gluconic acid and glycerine after incubation, and the treated nonwoven is the nonwoven with gluconic acid and glycerine after the incubation.

Result from the growth of bacteria measurement is shown in table 9.

Table 9

The bacteria growth measurement showed a high growth of all three tested bacteria species under the untreated nonwoven. Under the nonwoven treated with a skin-care composition with gluconic acid and glycerine treated, growth was decreased more for the unwanted species, E.coli (ATCC 10536) and S. aureus (ATCC 6538), compared to the beneficial Lplantarum (LB931 , clinical isolat). From the results above, it is apparent that a skin-care composition comprising glycerine and gluconic acid is beneficial for balancing the microflora on skin.

Claims

1. An absorbent hygiene article comprising a liquid permeable topsheet, and an absorbent core, wherein said topsheet is provided with a skincare composition provided on at least the side of the topsheet facing the user when the absorbent hygiene article is worn by the user characterized in that the skin-care composition is a dry coating comprising gluconic acid and a water miscible vehicle, such as glycerine, propylene glycol and/or PEG.

2. The article according to claim 1 wherein the amount of the water miscible vehicle is within the range of from 0.04 to 9.0 g/m², as measured over the area being coated.

3. The article according to claim 1 or 2, wherein the amount of the water miscible vehicle, in weight % of the dry coating, is at least 20 weight %, optionally between 20 and 90 weight %.

4. The article according to any of preceding claims, wherein the water miscible vehicle is glycerine.

5. The article according to claim 1 , wherein the amount of the gluconic acid is within the range of from 0.01 to 4.0 g/m², as measured over the area being coated.

6. The article according to any one of the preceding claims, wherein the dry coating is free from preservatives.

7. The article according to any of preceding claims, wherein the dry coating has a water activity less than 0.7, or less than 0.6.

8. The article according to any one of the preceding claims, wherein the amount of the gluconic acid, in weight % of the dry coating, is 5 to 40 weight-% of said dry coating.

9. The article according to any one of the preceding claims, wherein the dry coating further comprises a surfactant.

10. The article according to any one of the preceding claims, wherein said topsheet is a nonwoven web material or a perforated plastic film.

11 . The article according to any one of the preceding claims, wherein said topsheet has a dry basis weight of from 10 to 50 g/m².

12. The article according to any one of the preceding claims, wherein said absorbent core comprises from 10 to 100 wt% of super absorbent polymer.

13. The article according to any one of the preceding claims, wherein said dry coating is essentially homogenously distributed on the topsheet.

14. The article according to any one of the preceding claims, wherein said dry coating is applied in pattern covering from 10 to 90% of the area of the topsheet.

15. The article according to any of the preceding claims, wherein the absorbent core is disposed between the topsheet and a liquid impermeable backsheet.

16. The article according to any of the preceding claims wherein the article is a diaper, an incontinence shield, a sanitary napkin, a panty liner, a tampon or a wound dressing.

7. The use of an absorbent hygiene article as defined in any one of the preceding claims, for adjusting or maintaining the pH of skin in contact with said article at a value of from 3.5 to 5.5 as measured according to the method disclosed herein.