ITMI982147A1 - DISPOSABLE ABSORBENT ITEM - Google Patents

Description

DESCRIPTION of the industrial invention

The present invention relates to a disposable absorbent article.

In the production of disposable absorbent items, whether they are baby diapers, sanitary napkins, panty liners, potty training diapers, diapers without a locking system (known as pull-on diapers), diapers and sanitary pads for incontinent people, absorbent products for milk loss during breastfeeding (breast pads), have long established products in which the upper layer, in contact with the user's skin, called topsheet, has precise characteristics.

Certain characteristics are also typical of the barriers against spills, called barrier leg cuffs when placed adjacent to each longitudinal edge and waist cuffs when placed in correspondence with the terminal areas, barriers that may be present on the upper layer of the product facing the skin. of the user. In the present description, unless otherwise indicated, the term barriers against leakage means both the barrier leg cuffs and the waist cuffs.

The characteristics of the topsheet are such as to favor a rapid transfer of the liquid (for example urine) through the thickness of the topsheet, towards the absorbent area.

The topsheet itself also serves as a barrier to the return of liquid from the absorbent internal area to the surface, i.e. towards the user's skin.

This type of topsheet therefore allows to obtain a final product which quickly filters the exudated liquids towards the internal region where they are absorbed and which hinders their return to the surface.

The direct contact between the skin and the exudate liquid thus occurs for a very short time and the layer in contact with the skin remains substantially dry. The topsheet is also soft and non-irritating to the user's skin.

The described characteristics allow the upper layer or topsheet of a disposable absorbent product to minimize the possibility of irritation, abrasion or maceration of the user's skin.

For example, viscose topsheets have been made, but, given the poor ability of viscose to act as a barrier to the return of the liquid to the surface, the use of viscose has not proved to be optimal in the application for absorbent products intended for the collection of urine.

Similarly, after some attempts, natural fibers, such as cotton for example, have not found use, since, due to their high hydrophilic character, they give rise to topsheets that do not have a sufficient barrier effect to the return of the liquid from the area. absorbent lining towards the surface and are therefore not sufficiently dry in contact with the user's skin.

In the present application the term "hydrophilic" is used to describe fibers or fiber surfaces which are soaked by aqueous liquids in contact with the fibers themselves.

The degree of hydrophilicity of a material can be measured from time to time by determining the contact angle or the surface tension of the liquids and materials involved.

This measurement can for example be carried out using a Cahn SFA-222 Surface Force Analyzer System instrument. When the measurements are carried out with this instrument, according to the method described in the US-A-5,364,382 patent (column 21, lines 1-20), the fibers showing a contact angle lower than 90 ° are defined hydrophilic while those with an angle of contact greater than 90 ° are defined as hydrophobic.

The known art has dealt in various ways with the problem of making topsheets of disposable absorbent products with these characteristics and has solved this problem by using upper layers or topsheets, made with hydrophobic fibers, i.e. impermeable to water and aqueous liquids. , made hydrophilic, at least on the surface facing the user's skin, by treatment with surfactants, for example silicone polymers or polyethers.

In this way, by limiting the hydrophobia of the material, the likelihood that exudated body fluids will flow onto the topsheet instead of being absorbed by the internal absorbent area decreases. The materials used are generally nonwovens, called nonwovens, made up of synthetic fibers, such as polypropylene, polyester or artificial fibers such as viscose.

Spill barriers, called barrier leg cuffs when placed adjacent to each longitudinal edge and waist cuffs when placed at the end zones, were originally designed to mechanically stem the escape of droppings.

Subsequently there has been an evolution of the function of these barriers which, at the current state of the art, are commonly characterized by a certain degree of hydrophobia, thus allowing a certain containment of the exudated liquids and at the same time allowing the passage of air and the perspiration.

Similarly to what was observed in relation to the top-sheet, the use of highly hydrophilic fibers and in particular of natural fibers, such as cotton, has not found use in the production of barrier leg cuffs or waist cuffs, as they are made barriers with these fibers they would not constitute an obstacle for the passage of exudated liquids, which could escape outside the absorbent product.

Therefore these barriers are generally made, similarly to what has already been seen for the topsheet, with nonwovens, called nonwovens, made with hydrophobic synthetic fibers, in general polypropylene, in some cases treated with hydrophobic additives to strengthen the degree of hydrophobia.

Such nonwovens can be prepared by means of a thermobonding or spunbonding process, as known from the state of the art, and optionally treated with hydrophobic additives. In the case of the spunbonding process, these nonwovens are often made by combining hydrophobic fibers of different sizes, or characterized by different dtex, in order to obtain the desired degree of hydrophobia. These nonwovens are generally referred to as SM, SMS or SMMS as they are obtained through a spinning process that combines two well known technologies: Spunbonding and Meltblown. In particular, the spunbonding process is made with coarser fibers, from 1 to 3 dtex, while that of meltblown is made with extremely thin fibers, from 0.01 to 0.1 dtex. The spunbonded filaments give the nonwoven properties of softness and resistance, while the meltblown ones give the nonwoven properties of uniformity, coverage and hydrophobia.

In this way it is possible to obtain barriers against soft leaks in contact with the user's skin, non-irritating and with a certain degree of hydrophobia.

The present invention therefore proposes, taking into consideration the increasingly widespread need to use natural fibers in every type of fabric in contact with the skin, to identify an alternative solution for the realization of a disposable absorbent product that has the aforementioned fundamental characteristics and combines them with the use of a natural fiber, such as cotton, which due to its particular characteristics of naturalness, softness, biodegradability, less tendency to give allergies, irritation or redness, is more appreciated by the user.

The object of the present invention is therefore a disposable absorbent article comprising a body having an internal surface, an external surface arranged in opposition to the internal surface, longitudinal edges, a first terminal region and a second terminal region opposite the first, comprising a lower layer impermeable to liquids (called backsheet) and a permeable or filtering upper layer (called topsheet), an absorbent internal zone arranged between the upper layer and the lower layer, said article possibly being provided, on the surface facing the skin of the 'user of barriers against spillage, located adjacent to each longitudinal edge and / or located in correspondence with the terminal regions, characterized in that said upper filtering layer, permeable to liquids, consists of at least one layer of a material comprising cotton fibers, called avend material o a value of the measure of retrotransport of the liquid or Wet Back lower than or equal to 0.3 g and an acquisition time value or Liquid Strike Through Time lower than or equal to 3.5 seconds, and characterized by the fact that said possible barriers against spillages consist of at least one layer of a material comprising cotton fibers, said material having a height value of the water column or Wet Barrier Hydrostatic Head greater than or equal to 5 cm.

A further object of the present invention is the use of such disposable absorbent article as a baby diaper, sanitary napkin, panty liner, diaper for potty training, diaper-panty without a closure system (known as pull-on diaper ), diaper and absorbent for incontinent people, absorbent product for milk loss during breastfeeding (breast pads).

Preferably, said material comprising cotton fibers has a Wet Back value lower than or equal to 0.2 g and a Liquid Strike Through Time value lower than or equal to 3 seconds.In particular, the disposable absorbent article according to the present invention provides an upper layer filter or topsheet, comprising cotton fibers, having an average dtex value ranging from 1 to 5, preferably subjected to a previous hydrophobic treatment.

This hydrophobic treatment is carried out through the use of additives in an amount which increases with the increase in the percentage of cotton fiber present in the material and which decreases with the increase of the average dtex value of the cotton fiber.

The disposable absorbent article according to the present invention provides that for filtering layers or topsheets containing a percentage of cotton fibers lower than 95%, the same result is obtained also by selecting cotton fibers having a sufficiently average dtex value high, in relation to the percentage of cotton fibers used.

In the case in which the disposable absorbent article according to the present invention provides an upper filtering layer or topsheet, comprising cotton fibers not subjected to hydrophobic treatment, it is obtained by preferably selecting cotton fibers having an average value of dtex variable in the range from 2.5 to 5.

The disposable absorbent article according to the present invention can provide barriers against spillage comprising cotton fibers, having an average value of dtex varying in the range from 1 to 5, previously subjected to a hydrophobic treatment, where the percentage of cotton is between 5 and 100%.

The characteristics and advantages of the disposable absorbent article according to the present invention will be better understood from the following detailed and exemplary description, also relating to the attached figures 1-3.

The hydrophobic treatment that is carried out on the cotton fibers in both uses, i.e. to make the topsheet or the barriers against the leaks of the disposable absorbent article object of the present invention, varies according to the geometric characteristics of the cotton fibers. creates any type of damage to the fiber and does not irritate the user's skin.

As previously mentioned, the use of cotton fiber in the realization of the topsheet or of barriers against the spillage of a disposable absorbent article is not absolutely immediate and has required the resolution of several problems as an ordinary, untreated cotton fiber. o not selected on the basis of specific average dimensional characteristics, it does not meet the requirements set out above.

In fact, cotton itself is a hydrophilic fiber and therefore, as such, it cannot be used as an upper filtering layer in the production of absorbent articles because the fundamental characteristic of the topsheet is precisely that of favoring a rapid transfer of liquid (for example urine). through its thickness, towards the absorbent area and exert a barrier effect on the return of the liquid from the internal absorbent area towards the user's skin. The direct contact between the skin and the exudate liquid thus occurs for a very short time and the layer in contact with the skin remains substantially dry.

All the more reason, any cotton fiber cannot be used for the realization of barriers against leakage, barriers characterized by a certain degree of hydrophobia, due to the hydrophilic characteristics that make it a highly permeable material to such liquids.

A) The topsheet

Precisely in order to obtain a filtering or dry topsheet, as already indicated, the topsheets currently used on the market are preferably based on polypropylene, i.e. intrinsically hydrophobic polymeric fibers, which are subjected to a hydrophilizing treatment, to allow the exuded liquid to flow. on the surface of the fibers and therefore to move away from the skin penetrating towards the internal absorbent area and at the same time act as a barrier to the return of the liquid to the surface, thanks to the hydrophobic characteristics maintained.

Given their high hydrophilicity, a topsheet containing any cotton fibers has the following characteristics:

1. is adequately filtering. In fact, it allows the rapid passage of the liquid through its thickness, towards the internal absorbent region; 2. it is not adequately dry in contact with the user's skin. In fact, it does not exert an adequate barrier effect against the return of the liquid to the surface.

As we will see later, the two data that are measured and allow to evaluate the validity of a material such as topsheet, are the "Wet Back" and the "Liquid Strike Through Time".

The Wet Back value, as defined in the ERT 151.1-96 method recommended by EDANA (European Disposable And Nonwovens Association) quantifies the ability of the tophseet to act as a barrier to the return to the skin of the liquid already filtered from the topsheet itself.

In practice, the quantity of liquid filtered from the topsheet and absorbed by a standard pad is detected, liquid that crosses the topsheet again under the effect of a standard pressure applied. The smaller the quantity of liquid that, released from the standard pad, crosses the topsheet again and returns to the surface of the absorbent article where it is measured, i.e. the lower the Wet Back value, the more effective is the barrier effect exerted. and therefore the more the material is suitable for making a topsheet.

It can therefore be summarized that a low Wet Back value demonstrates that the topsheet has no tendency to retro-transport the already filtered liquid towards the skin.

The "Liquid Strike Through Time" test, as defined in the ERT 150.3-96 method recommended by EDANA, measures the time taken by a known volume of liquid, applied to the surface of a topsheet specimen, placed on top of a standard absorbent pad, to go through the topsheet itself.

A low value of Liquid Strike Through Time demonstrates that the topsheet has a high tendency to filter the liquid quickly towards the absorbent inner region.

From the above it follows that, since a topsheet must have a high barrier effect towards the return to the surface of the liquid and also excellent filtering capacities to quickly convey the liquid towards the absorbent internal region, theoretically the performance of the material will be the better the lower will be the Wet Back and Liquid Strike Through Time values.

In reality, since the Wet Back value is linked to the hydrophobic characteristics of the topsheet and the Liquid Strike Through Time value to the hydrophilic ones, it is necessary to balance the two characteristics, obtaining the optimal equilibrium value for the creation of an adequately dry and filtering topsheet. .

Any cotton fiber, given its high hydrophilicity, has an absolutely inadequate Wet Back value and is therefore not usable for the creation of a topsheet that acts as a barrier to the return to the surface of the absorbed liquid, despite being characterized by a good value. by Liquid Strike Through Time.

It is therefore not possible to use any cotton fiber in the production of the topsheet, for the disposable absorbent article object of the present application, since an excessively moist layer would be obtained in contact with the user's skin.

The cotton fiber used for the production of the disposable absorbent article according to the present invention is a cotton fiber selected on the basis of precise dimensional characteristics or average values of dtex and / or suitably treated so as to give it certain hydrophobic characteristics, reaching thus the desired balance point between filtering capacities (low value of Liquid Strike Through Time) and effective barrier effect (low value of Wet Back).

In particular, it can be cotton fiber such as available from Edward Hall Ltd. (England).

These cotton fibers have been subjected to a treatment that limits their hydrophilic properties through the use of suitable additives such as waxes, in emulsion or dispersion in hot water, in a percentage between 0.01 and 40% by weight. compared to the amount of cotton. In particular, these additives can be used in an amount ranging from 0.5 to 10% by weight.

The hydrophobic treatment on cotton fibers varies according to the geometric characteristics of the cotton fibers. In particular, the amount of hydrophobic additive that must be added decreases as the average dtex value of the fibers used increases.

In the present description, the term dtex refers to the weight in grams of a ten thousand meter long fiber.

In particular, as previously indicated, the disposable absorbent article according to the present invention provides that the upper filtering layer, permeable to liquids, is constituted by at least one layer of a material comprising cotton fibers, having a variable average value of dtex. in the range from 1 to 5, said cotton fibers having preferably been subjected to a previous hydrophobic treatment.

The topsheet made with the cotton fibers just described has the following characteristics:

• acts as a barrier to the return of the liquid towards the surface and the skin of the user

• allows the exudate liquid to pass through quickly.

Such characteristics have been measured, by way of example, for different types of material, which can be used as a topsheet or as a layer containing cotton fibers of the topsheet, for the disposable absorbent article according to the present invention and the results are reported in following table.

In particular, the methods used for the measurement of Wet Back and Liquid Strike Through Time are the standard methods suggested and recommended by EDANA.

Material parameter

Method

A1 A2 A3 B1 B2 C

Wet Back 6.4 g 0.1 g 0.1 g 13.5 g 0.1 g 0.1 g EDANA ERT 150.3-96

LiquidStrike 2.7s 2.5S 2.5s 2.2S 2.5s 2.53 Through Time

EDANA ERT 151.1-96

Example A1.

In the previous table, material Al means a material consisting of 30% of cotton fibers not subjected to hydrophobic treatment and 70% of polypropylene fibers, this material having been prepared through a carding and heat-calender process (process known as thermobonding ) and having a grammage of 22 g / m <2> and an average dtex value of the cotton fibers equal to 1.2.

The topsheet made with the Al material does not exert a barrier effect to the return of wet to the surface, as evidenced by the high value of Wet Back, while it has good filtering properties, as evidenced by the low value of Liquid Strike Through Time.

This demonstrates how a topsheet containing any cotton fibers, ie having unsuitable, untreated dimensional characteristics, is not adequately dry.

Example A2.

In the previous table, material A2 means a material consisting of 30% of cotton fibers subjected to hydrophobic treatment, in particular treated with 3 g of additive per 100 g of cotton fibers and 70% of polypropylene fibers, this material having been prepared through a carding and heat-calender process (process known as thermobonding) and having a weight of 22 g / m <2> and an average dtex value of the cotton fibers equal to 1.2.

The topsheet made with A2 material exerts a good barrier effect to the return of wet to the surface, as evidenced by the content of Wet Back, and maintains good filtering properties, as evidenced by the low value of Liquid Strike Through Time.

This demonstrates how according to the present invention it is possible to produce a topsheet for disposable absorbent article, containing cotton fibers treated with an adequate quantity of hydrophobic additive in order to achieve the desired balance between barrier effect and filtering characteristics.

Example A3.

In the previous table, material A3 means a material consisting of 30% of cotton fibers not subjected to hydrophobic treatment and 70% of polypropylene fibers, this material having been prepared by means of a carding and heat-calender process (process known as thermobonding ) and having a weight of 22 g / m <2> and an average dtex value of the cotton fibers equal to 3.

The topsheet made with A3 material exerts a good barrier effect to the return of wet to the surface, as evidenced by the content of Wet Back, and also has good filtering properties, as evidenced by the low value of Liquid Strike Through Time.

This demonstrates how according to the present invention it is possible to make a topsheet for a disposable absorbent article, containing selected cotton fibers with precise and well-defined dimensional characteristics, i.e. with precise and defined average values of dtex, so as to achieve the desired balance between barrier effect and filtering characteristics.

Example B1.

In the previous table, material Bl means a material made up of 100% untreated cotton, this material having been prepared through a hydroentanglement process and having a weight of 40 g / m <2> and an average dtex value of the fibers of cotton equal to 1.2.

The topsheet made with the Bl material does not exert a barrier effect to the return of wet to the surface, as evidenced by the high value of Wet Back, while it has good filtering properties, as evidenced by the low value of Liquid Strike Through Time.

This shows, once again, how a topsheet containing untreated cotton fibers is not adequately dry.

Example B2.

In the previous table for material B2 we mean a material consisting of 100% treated cotton, in particular with 3 g of additive per 100 g of cotton fibers, this material having been prepared through a hydroentanglement process and having a weight of 40 g / m <2> and an average dtex value of the cotton fibers equal to 1.2.

The topsheet made with B2 material exerts a good barrier effect against the return of wet to the surface, as evidenced by the content of Wet Back, and maintains good filtering properties, as evidenced by the low value of Liquid Strike Through Time.

This demonstrates how according to the present invention it is also possible to produce a topsheet for disposable absorbent article, only with cotton fibers treated with an adequate quantity of hydrophobic additive in order to achieve the desired balance between barrier effect and filtering characteristics.

Example C.

In the previous table, material C refers to a traditional type topsheet, as commonly used in the current technique, consisting of 100% polypropylene, treated with hydrophilizing treatment as known in the state of the art and in particular with 0.5 g of hydrophilizing additive per 100 g of polypropylene fibers, prepared according to a thermobonding process and having a grammage of 22 g / m <2>.

The topsheet made with material C exerts a good barrier effect against the return of wet to the surface, as evidenced by the content of Wet Back, and has acquired, thanks to the hydrophilizing treatment, good filtering properties, as evidenced by the low value of Liquid Strike Through Time.

The values obtained with material C are completely comparable with those obtained for materials A2, A3 and B2, which demonstrates how the topsheet with cotton fibers according to the present invention has the same performance as a traditional topsheet.

As previously indicated, the disposable absorbent article according to the present invention provides an upper filtering layer or topsheet comprising cotton fibers, having an average value of dtex varying in the range from 1 to 5, said cotton fibers having preferably been subjected to a previous hydrophobic treatment, and where the percentage of cotton is between 5 and 100%

In particular, the topsheet filtering layer of the disposable absorbent article according to the present invention has a weight of between 10 and 300 g / m <2>. Preferably the weight of the filtering layer is between 14 and 40 g / m <2> when the percentage by weight of cotton in the topsheet is between 5 and 50% and between 25 and 60 g / m <2> when the percentage the weight of the cotton treated in the topsheet is 100%.

The cotton fiber used in the production of the topsheet of the disposable absorbent article according to the present invention preferably has average values of dtex comprised between 1.2 and 3.5.

These dimensional characteristics make it possible to optimize the carding process on the one hand and the performance in terms of release on the other.

The carding process is optimized because if the cotton fibers are "thicker", for the same percentage by weight, there will be a lower number of fibers for cotton than for polypropylene, and, consequently, fewer welding points (bonding points) difficult to make, as cotton does not melt.

Regarding the performance in terms of release, it is very important that the cotton fiber has an appropriate size and in particular a high dtex value, to decrease the wettable surface and the Surface to Volume (S / V) ratio.

As previously noted, the disposable absorbent article according to the present invention is preferably made with cotton fibers not subjected to any hydrophobic treatment when the cotton fibers are characterized by precise and well-defined dimensional parameters, i.e. when they have average values of dtex between 2.5 and 5, preferably equal to 3. The hydrophobic treatment can still be carried out on fibers having such dimensions.

In this way, an optimization of various characteristics of the topsheet is obtained which, at the same time, allows the passage of the exudate liquid towards the absorbent pad with a sufficiently high speed and constitutes a barrier to the return of the liquid to the surface, remaining dry in contact with the skin. .

A further object of the present invention is also a disposable absorbent article comprising a body having an internal surface, an external surface arranged in opposition to the internal surface, longitudinal edges, a first terminal region and a second terminal region opposite the first, comprising a lower layer impermeable to liquids (called backsheet) and a permeable or filtering upper layer (called topsheet), an absorbent internal zone arranged between the upper layer and the lower layer, said upper filtering layer, permeable to liquids, consisting of at least a layer of material comprising cotton fibers, said material having a Wet Back value less than or equal to 0.3 g and a Liquid Strike Through Time value less than or equal to 3.5 seconds, and where said topsheet is prepared by means of a thermobonding process, of airthrough bonding, resin bonding or hydroentanglement.

Different methods can in fact be used for the realization of the topsheet.

A first procedure for the preparation of the topsheet is the thermobondig procedure; it foresees that the cotton fibers are mixed with the polypropylene fibers, carded on one or more layers and finally passed under a calender which, by means of the combined action of pressure and heat, imprisons them inside the welded matrix of the fibers of polypropylene.

In particular, in the case in which the topsheet containing cotton fibers of the disposable absorbent article according to the present invention is made by thermobonding it has a percentage by weight of cotton comprised between 5 and 50%, a grammage comprised between 10 and 50 g / m <2> and preferably between 14 and 26 g / m <2> and average dtex values of the cotton fibers between 1.2 and 3.5.

Preferably the percentage by weight of treated cotton is 30%.

A second method for making a topsheet is the airthrough bonding method.

It provides that the cotton fibers are mixed with the polypropylene fibers, carded on one or more layers and finally welded by means of a flow of hot air.

In particular, in the case in which the topsheet containing cotton fibers of the disposable absorbent article according to the present invention is made by airthrough bonding, it has a percentage by weight of cotton comprised between 5 and 50%, a grammage comprised between 10 and 300 g / m <2>, preferably between 14 and 40 g / m <2> and average dtex values of the cotton fibers between 1.2 and 3.5.

These thermobonding and airthrough bonding processes obviously cannot be used if the topsheet is made up exclusively of cotton fibers.

In this case, in fact, the topsheet containing cotton fibers of the disposable absorbent article according to the present invention is made by means of the so-called hydroentanglement process where the percentage of cotton in the topsheet can reach 100% and the weights can reach 100 g / m <2>.

In fact, when the topsheet is made by hydroentanglement process, i.e. using high pressure water jets, the topsheet has a weight percentage of cotton between 5 and 100%, preferably 100%, a grammage between 10 and 100 g / m <2>, preferably between 25 and 60 g / m <2> and average dtex values of the cotton fibers between 1.2 and 3.5.

Other processes that can be used are, for example, "resin bonding" which consists of a carding process followed by the bonding of fibers by means of resins.

It allows you to work with cotton percentages higher than those allowed by thermobonding and airthrough bonding.

In fact, when the topsheet according to the present invention is made by resin bonding, it has a percentage by weight of the cotton between 5 and 90%, a grammage between 10 and 60 g / m <2>, preferably between 14 and 30 g / m <2> and average dtex values of the cotton fibers between 1.2 and 3.5.

Otherwise it is possible to laminate a material comprising cotton fibers, made by one of the aforesaid processes and coupled by means of adhesives or ultrasonic welding to a nonwoven topsheet made with synthetic fibers.

The disposable absorbent article according to the present invention can in fact also provide a topsheet consisting of at least two coupled layers, of which one layer, placed in contact with the user's skin, is made up of material comprising cotton fibers, this layer being then coupled to one or more layers, facing the absorbent internal area and consisting of a traditional topsheet, based on artificial fibers, such as for example polypropylene, said coupled composite material having a Wet Back value lower than or equal to 0.3 g and a Liquid Strike Through Time value less than or equal to 3.5 seconds.

In this application, the percentage by weight of cotton, in the layer in contact with the skin, can be between 5 and 100%, preferably between 70 and 100%, with a weight between 5 and 100 g / m <2>, preferably between 5 and 60 g / m <2> and average dtex values of the cotton fibers between 1.2 and 3.5.

B) Spill barriers.

As previously indicated, in the evolution of the role of barriers against leakage it has become very important that they present a certain degree of hydrophobia, thus allowing a certain containment of exudated liquids and at the same time allowing the passage of air and transpiration.

This containment of exudated liquids can be measured by the test known as "Wet Barrier Hydrostatic Head".

The Wet Barrier Hydrostatic Head measurement, as defined in the ERT 160.0-89 method recommended by EDANA, defines the resistance of a non-woven or nonwoven to the penetration of aqueous liquids.

This property is measured indirectly by detecting the minimum height of the water column that must be applied to the material under examination in order for the first drop of water to pass through the thickness of the material.

By carrying out measurements according to this method, the height of the water column supported by barriers against spills with a certain containment of the exuded liquids of absorbent products on the market, is generally equal to or greater than 5 cm.

Barriers against spillages made with a nonwoven containing cotton fibers, which as known have a high hydrophilicity, would show a low value of Wet Barrier Hydrostatic Head. In fact, the hydrophilicity of the cotton fibers gives the entire nonwoven hydrophilic properties and consequently shows practically no containment properties of the exudated liquids.

The cotton fiber used for the realization of the barriers against the leakage of the disposable absorbent article according to the present invention is a cotton fiber having an average value of dtex variable in the range from 1 to 5, previously subjected to a hydrophobic treatment , and therefore able to reach the desired level of hydrophobia and therefore a certain containment of exudated liquids (high value of Wet Barrier Hydrostatic Head).

In particular, it can be cotton fiber such as available from Edward Hall Ltd. (England).

These fibers have undergone a treatment that limits their hydrophilic properties through the use of suitable additives such as waxes, in emulsion or dispersion in hot water, in a percentage between 0.01 and 40% by weight with respect to the amount of cotton. In particular, these additives can be used in an amount comprised between 5 and 25% by weight.

The leakage barriers according to the present invention consist of at least one layer of material comprising cotton fibers, having an average dtex value ranging from 1 to 5, said cotton fibers having previously been subjected to a hydrophobic treatment, where said material is prepared by means of a thermobonding or hydroentanglement process.

As previously disclosed, the disposable absorbent article according to the present invention can provide on the surface facing the user's skin, barriers against spillages consisting of at least one layer of material comprising cotton fibers, having a variable average value of dtex. in the range from 1 to 5, previously subjected to a hydrophobic treatment, where the percentage of cotton is between 5 and 100%.

The material used to make the barriers against the leakage of the disposable absorbent article according to the present invention has a weight of between 5 and 100 g / m <2>.

Preferably, the weight of the spillage barriers is between 10 and 50 g / m <2> when the percentage by weight of cotton treated in the barriers is between 5 and 50% and between 25 and 60 g / m <2> when the percentage by weight of the treated cotton is 100%.

The cotton fiber used in the realization of the barriers against the leakage of the disposable absorbent article according to the present invention has average dimensional characteristics between 1 and 5 dtex. In particular, according to the present invention, cotton fibers having an average size ranging from 1.2 to 3.5 dtex are preferably used.

The hydrophobic characteristics previously considered were measured, by way of example, for different types of material containing cotton fibers, which can be used as a spill barrier for the disposable absorbent article according to the present invention and the results are reported. in the following table.

In particular, the method used to measure the Wet Barrier Hydrostatic Head is one of the two standard methods suggested and recommended by EDANA to measure the resistance of a nonwoven to the penetration of liquids.

Example D1.

In the previous table for material D1 we mean a material consisting of 30% of cotton fibers not subjected to hydrophobic treatment and 70% of polypropylene fibers, this material having been prepared through a carding and heat-calandering process (process known as thermobonding ) and having a weight of 20 g / m <2>.

Spillage barriers made with E1 material do not have a sufficient degree of hydrophobia, as evidenced by the impossibility of measuring a Wet Barrier Hydrostatic Head value, as the water column does not form due to the immediate passage of the liquid through the thickness of the material.

Example D2.

In the previous table, material D2 means a material consisting of 30% of cotton fibers subjected to hydrophobic treatment, in particular with 6 g of hydrophobic additive per 100 g of cotton fibers, and 70% of polypropylene fibers, such material having been prepared through a carding and heat-calender process (process known as thermobonding) and having a weight of 20 g / m <2>.

The spill barriers made with D2 material have acquired a certain degree of hydrophobia and therefore liquid containment properties, as evidenced by the Wet Barrier Hydrostatic Head value.

Example D3.

In the previous table, material D3 means a material consisting of 30% of cotton fibers subjected to hydrophobic treatment, in particular with 15 g of hydrophobic additive per 100 g of cotton fibers, and 70% of polypropylene fibers, such material having been prepared through a carding and heat-calender process (process known as thermobonding) and having a weight of 20 g / m <2>.

Spillage barriers made with D3 material have a high degree of hydrophobia and therefore liquid containment properties, as evidenced by the Wet Barrier Hydrostatic Head value of 15 cm.

Example E1.

In the previous table, material E1 means a material consisting of 100% cotton fibers not subjected to hydrophobic treatment, this material having been prepared by means of a hydroentanglement process and having a weight of 27 g / m <2>.

Spillage barriers made with E1 material do not have any hydrophobic characteristics, as evidenced by the impossibility of measuring a Wet Barrier Hydrostatic Head value, as the water column does not form due to the immediate passage of the liquid through the thickness of the material.

Example E2.

In the previous table, material E2 means a material consisting of 100% cotton fibers subjected to hydrophobic treatment, in particular treated with 6 g of hydrophobic additive per 100 g of cotton fibers, this material having been prepared through a hydroentanglement process and having a weight of 27 g / m <2>.

The spill barriers made with the E2 material have acquired a certain degree of hydrophobia and therefore liquid containment properties, as evidenced by the Wet Barrier Hydrostatic Head value.

Example E3.

In the previous table, material E3 means a material consisting of 100% cotton fibers subjected to hydrophobic treatment, in particular treated with 20 g of hydrophobic additive per 100 g of cotton fibers, this material having been prepared by means of a process of hydroentanglement and having a grammage of 27 g / m <2>.

Spillage barriers made with D3 material have a high degree of hydrophobia and therefore liquid containment properties, as evidenced by the Wet Barrier Hydrostatic Head value of 15 cm.

Example F.

In the previous table, material F means a material made up of 100% polypropylene fibers, subjected to hydrophobic treatment, in particular treated with 0.5 g of additive per 100 g of polypropylene fibers, this material having been prepared according to the technique known as SMS by coupling two layers of spunbonded material and one meltblown and having an overall weight of 20 g / m <2>.

The values obtained with material F are completely comparable with those obtained for materials D3 and E3, which demonstrates how the barriers against spillage made with cotton fibers according to the present invention have a degree of hydrophobia and therefore the ability to exercise a certain degree of containment of exudated liquids, comparable to those of traditional barriers against leaks, as achieved with the current technique and with liquid containment properties.

The disposable absorbent article according to the present invention can also provide barriers against leaks consisting of at least two coupled layers, of which one layer, placed in contact with the user's skin, is made of material comprising cotton fibers, while the remaining wine or more layers, positioned towards the inside, not in contact with the user's skin, are made up of synthetic fibers, where said coupled composite material has an average value of Wet Barrier Hydrostatic Head greater than or equal to 5 cm.

In particular, the layer placed in contact with the user's skin is made up of a material comprising cotton fibers having an average dtex value ranging from 1 to 5, said cotton fibers having previously been subjected to a hydrophobic treatment.

Brief description of the figures.

Figure 1 is a plan view of a first simplified embodiment of an absorbent article according to the present invention.

Figure 2 is a section of an enlarged detail along the line II-II of the simplified embodiment of the absorbent article according to the present invention of Figure 1.

Figure 3 is a plan view of a further simplified embodiment of an absorbent article according to the present invention.

In particular, this first embodiment represents a baby diaper 10, with in the foreground the internal surface, called topsheet, permeable to liquids 11. This diaper 10 has a topsheet 11, a waterproof backsheet 12 and an absorbent internal region 13, which can be consisting of several layers, for example layers of wadding, fluff and superabsorbent polymer, acquisition layer, as known in the current art, positioned between the topsheet 11 and the backsheet 12, said internal absorbent region having a surface 14 facing the direction opposite to the body, i.e. towards the garment, a surface 15 directed towards the skin, side edges 16, waist edge 17, a first terminal region 18 and a second terminal region 18 ', arranged in an opposite position with respect to the first. The diaper 10 also provides elasticized zones 19 which close around the legs, and a closure system 21. The diaper 10, represented in simplified form in Figures 1 and 2, is also provided with barriers against leakage (barrier leg cuffs) 27 and 27 ', at each longitudinal edge 25.

The particular embodiment of the disposable absorbent article according to the present invention, i.e. of the baby diaper 10, shown in Figure 1, also shows an external surface 22 and an internal surface 23 opposite the surface 22, a periphery 24 which is defined by outer edges of the diaper 10 in which the longitudinal edges are indicated with 25, while the upper and lower edges are indicated with 26.

The external surface 22 of the diaper 10 constitutes the portion of the diaper 10 not in contact with the skin but with the user's garment and is generally constituted by the backsheet 12 and any other components that can be joined to the backsheet 12.

The internal surface 23 of the diaper 10 constitutes the portion of the diaper 10 in contact with the user's skin and is generally constituted by the topsheet 11 and by any other components which can be joined to the topsheet such as for example the side barriers against leaks (barrier leg cuffs) 27 and 27 '.

The further embodiment shown in Figure 3 represents a sanitary napkin 28, with in the foreground the internal surface, called topsheet, permeable to liquids 29. This absorbent 28 has a topsheet 29, a waterproof backsheet 30 and an absorbent internal region 31 which, as known in the current art, it can be constituted by different layers, for example by layers of wadding, fluff and superabsorbent polymer, and by a possible acquisition layer, said internal absorbent region 31, being positioned between the topsheet 29 and the backsheet 30 . In the particular embodiment shown in Figure 3, the topsheet 29 and the backsheet 30 have the same dimensions which are larger than those of the absorbent internal region 31. The topsheet 29 overlaps the backsheet 30 in the lateral region 32 and in a second lateral region 32 ', arranged in an opposite position with respect to the absorbent internal region 31 of the absorbent 28.

Furthermore, the absorbent 28 has a surface 33 towards the direction opposite to the body, that is towards the garment, a surface 34 directed towards the skin and lateral edges 35. It also provides, in the particular embodiment shown in Figure 3, two lateral regions 36, said wings, outside the regions 32 and 32 ', said regions 36 being provided with adhesive means 37. The aforementioned lateral regions 36 may in any case not be present. The sanitary napkin 28 is also provided with an adhesive system for fixing it to the underwear 38 and can also possibly provide barriers against leaks 39, arranged longitudinally.

The disposable absorbent article according to the present invention therefore allows the skin of the child or of the user to be completely enveloped by the topsheet and, when present, by the barriers against leakage barrier leg cuffs and waist cuffs, i.e. by materials comprising fibers of cotton having an average dtex value ranging from 1 to 5, preferably subjected to a previous hydrophobic treatment when this dtex value varies from 1 to 2.5 in the case of the topsheet and previously subjected to a hydrophobic treatment when this value of dtex varies from 1 to 5 in the case of barriers.

The main advantage of the disposable absorbent article according to the present invention is therefore that of using a natural fiber, in particular cotton which, due to its particular characteristics of softness, biodegradability, naturalness, less tendency to give allergies, irritation or redness , is more pleasing to the user, but at the same time creating a topsheet, i.e. a layer in contact with the user's skin that is dry and effectively filtering and, where present, barriers against leaks, barrier leg cuffs and waist cuffs, with a high degree of hydrophobia.

Furthermore, the disposable absorbent article according to the present invention has the further advantage of a greater, albeit minimal, biodegradability of the final product.

Having described the invention in some detail, it is immediately evident that various modifications can be made without thereby departing from its content. These modifications are to be understood as belonging to the sphere of the invention, as defined by the following claims.

Claims (43)

CLAIMS 1. Disposable absorbent article comprising a body having an internal surface, an external surface disposed in opposition to the internal surface, longitudinal edges, a first terminal region and a second terminal region opposite the first, comprising a lower layer impermeable to liquids (called backsheet) and a permeable or filtering upper layer (called topsheet), an absorbent internal zone arranged between the upper layer and the lower layer, said article possibly being provided, on the surface facing the user's skin, with barriers against the spills, located adjacent to each longitudinal edge and / or located in correspondence with the terminal regions, characterized in that said upper filtering layer, permeable to liquids, consists of at least one layer of a material comprising cotton fibers, said material having a Wet Back value less than or equal to 0.3 g and a Liquid Strike Through Time value less than or equal to 3.5 seconds, and characterized by the fact that said possible barriers against leakage are made up of at least one layer of a material comprising cotton fibers, said material having a Wet Barrier Hydrostatic value Head greater than or equal to 5 was. 2. Disposable absorbent article according to claim 1, characterized in that said material comprising cotton fibers has a Wet Back value lower than or equal to 0.2 g and a Liquid Strike Through Time value lower than or equal to 3 seconds 3. Disposable absorbent article according to claim 1, characterized in that the upper filtering layer or topsheet comprises cotton fibers having an average value of dtex variable in the range from 1 to 5 and said possible barriers against leakage consist of at least one layer of a material comprising cotton fibers having an average dtex value ranging from 1 to 5, previously subjected to a hydrophobic treatment. 4. Disposable absorbent article according to claim 3, characterized in that the cotton fibers of the upper filtering layer or topsheet have previously been subjected to a hydrophobic treatment. 5. Disposable absorbent article according to claim 3, characterized in that the cotton fibers of the upper filtering layer or topsheet have an average value of dtex varying in the range from 2.5 to 5. 6. Disposable absorbent article according to claim 1, characterized in that the upper filtering layer or topsheet and the spillage barriers have a percentage by weight of cotton fibers comprised between 5 and 100%. 7. Disposable absorbent article according to claim 1, characterized in that the percentage by weight of cotton fiber in the topsheet is about 30%. 8. Disposable absorbent article according to claim 3, characterized in that the cotton fiber used for the topsheet and for the spillage barriers, is previously subjected to a hydrophobic treatment by using additives in a percentage comprised between 0.01 and 40% by weight with respect to the amount of cotton. 9. Disposable absorbent article according to claim 8, characterized in that said additives are used in an amount ranging from 0.5 to 10% by weight with respect to the amount of cotton in the case of the topsheet and in an amount ranging from 5 and 25% by weight with respect to the amount of cotton in the case of barriers. Disposable absorbent article according to claim 4, characterized in that the cotton fiber of the topsheet and of the spillage barriers has an average dtex value of between 1.2 and 3.5. 11. Disposable absorbent article according to claim 10, characterized in that the cotton fiber has an average dtex value equal to 3. Disposable absorbent article according to claim 1, characterized in that the topsheet filtering layer has a weight of between 5 and 300 g / m <2>. 13. Disposable absorbent article according to claim 12, characterized in that the weight of the filtering layer is between 14 and 40 g / m <2> when the percentage by weight of cotton is between 5% and 50% . 14. Disposable absorbent article according to claim 12, characterized in that the weight of the filtering layer is between 25 and 60 g / m <2> when the percentage by weight of cotton is 100%. 15. Disposable absorbent article according to claim 1, characterized in that barriers against leakage have a grammage comprised between 10 and 100 g / m <2>. 16. Disposable absorbent article according to claim 1, characterized in that the outer topsheet layer is constituted by at least two coupled layers, of which one layer, placed in contact with the user's skin, is constituted by material comprising fibers of cotton, this layer being then coupled to one or more layers, facing the absorbent internal area and consisting of a traditional topsheet, based on synthetic fibers, said coupled composite material having a Wet Back value lower than or equal to 0.3 g and a value Liquid Strike Through Time less than or equal to 3.5 seconds. 17. Disposable absorbent article according to claim 16, characterized in that the layer placed in contact with the user's skin is made of material comprising cotton fibers having an average value of dtex varying in the range from 1 to 5 , said cotton fibers having been preferably subjected to a previous hydrophobic treatment. 18. Disposable absorbent article according to claim 1, characterized in that the spillage barriers consist of at least two coupled layers, of which one layer, placed in contact with the user's skin, consists of material comprising fibers cotton, while the remaining one or more layers, internal and not in contact with the user's skin, are made of synthetic fibers, said composite material coupled having a Wet Barrier Hydrostatic Head value greater than or equal to 5 cm. 19. Disposable absorbent article according to claim 18, characterized in that the layer placed in contact with the user's skin is made up of a material comprising cotton fibers having an average value of dtex varying in the range from 1 to 5 , said cotton fibers having previously been subjected to a hydrophobic treatment. 20. Disposable absorbent article according to claim 16, characterized in that the percentage by weight of cotton, in the layer in contact with the skin, is preferably between 70 and 100% and has a grammage between 5 and 60 g / m <z>. 21. Disposable absorbent article comprising a body having an internal surface, an external surface arranged in opposition to the internal surface, longitudinal edges, a first terminal region and a second terminal region opposite the first, comprising a lower layer impermeable to liquids (called backsheet) and a permeable or filtering upper layer (called topsheet), an absorbent internal zone arranged between the upper layer and the lower layer, said article possibly being provided, on the surface facing the user's skin, with barriers against the spills, located adjacent to each longitudinal edge and / or located in correspondence with the terminal regions, characterized in that said upper filtering layer, permeable to liquids, consists of at least one layer of a material comprising cotton fibers, said material having a lower or equal Wet Back value at 0.3 g and a Liquid Strike Through Time value lower than or equal to 3.5 seconds, said topsheet being prepared by thermobonding or airthrough bonding process and characterized in that said possible barriers consist of at least one layer of a material comprising cotton fibers , said material having a Wet Barrier Hydrostatic Head value greater than or equal to 5 cm, said possible barriers being prepared by means of a thermobonding or hydroentanglement process. 22. Disposable absorbent article according to claim 21, characterized in that the topsheet is constituted by a material comprising cotton fibers having an average dtex value between 1 and 5, preferably subjected to a previous hydrophobic treatment, and said possible barriers consist of a material comprising cotton fibers having an average dtex value between 1 and 5, previously subjected to a hydrophobic treatment. 23. Disposable absorbent article according to claim 21, characterized in that the topsheet has a percentage by weight of cotton comprised between 5 and 50%, preferably 30%, a grammage comprised between 10 and 50 g / m < 2>, preferably between 14 and 26 g / m <2> and an average dtex value of the cotton fibers between 1.2 and 3.5 when the tophseet is prepared by the thermobonding process. 24. Disposable absorbent article according to claim 21, characterized in that the topsheet has a percentage by weight of cotton comprised between 5 and 50%, preferably 30%, a grammage comprised between 10 and 300 g / m < 2>, preferably between 14 and 40 g / m <2> and an average dtex value of the cotton fibers between 1.2 and 3.5, when the tophseet is prepared by means of the airthrough bonding process. 25. Disposable absorbent article according to claim 21, characterized in that the cotton fiber has an average dtex value equal to 3. 26. Disposable absorbent article comprising a body having an internal surface, an external surface disposed in opposition to the internal surface, longitudinal edges, a first terminal region and a second terminal region opposite the first, comprising a lower layer impermeable to liquids (called backsheet) and a permeable or filtering upper layer (called topsheet), an absorbent internal zone arranged between the upper layer and the lower layer, said article possibly being provided, on the surface facing the user's skin, with barriers against the spills, located adjacent to each longitudinal edge and / or located in correspondence with the terminal regions, characterized in that said upper filtering layer, permeable to liquids, consists of at least one layer of a material comprising cotton fibers, said material having a Wet Back value, lower or equal at 0.3 g and a Liquid Strike Through Time value lower than or equal to 3.5 seconds, said topsheet being prepared by a resin bonding process and characterized in that said possible barriers consist of at least one layer of a material comprising cotton fibers, said material having a Wet Barrier Hydrostatic Head value greater than or equal to 5 cm, said possible barriers being prepared by means of a thermobonding or hydroentanglement process. 27. Disposable absorbent article according to claim 26, characterized in that the topsheet is constituted by a material comprising cotton fibers having an average dtex value between 1 and 5, preferably subjected to a previous hydrophobic treatment, and said possible barriers consist of a material comprising cotton fibers having an average dtex value between 1 and 5, previously subjected to a hydrophobic treatment. 28. Disposable absorbent article according to claim 26, characterized in that the topsheet has a weight percentage of cotton comprised between 5 and 90%, a grammage comprised between 10 and 60 g / m <2>, preferably between 14 and 30 g / m <2> and an average dtex value of the cotton fibers between 1.2 and 3.5. 29. Disposable absorbent article according to claim 26, characterized in that the cotton fiber has an average dtex value equal to 3. 30. Disposable absorbent article comprising a body having an internal surface, an external surface disposed in opposition to the internal surface, longitudinal edges, a first terminal region and a second terminal region opposite the first, comprising a lower layer impermeable to liquids (called backsheet) and a permeable or filtering upper layer (called topsheet), an absorbent internal zone arranged between the upper layer and the lower layer, said article possibly being provided, on the surface facing the user's skin, with barriers against the spills, located adjacent to each longitudinal edge and / or located in correspondence with the terminal regions, characterized in that said upper filtering layer, permeable to liquids, consists of at least one layer of a material comprising cotton fibers, said material having a Wet Back value less than or equal to 0.3 g and a Liquid Strike Through Time value lower than or equal to 3.5 seconds, said topsheet being prepared by hydroentanglement process and characterized in that said possible barriers consist of at least one layer of a material comprising cotton fibers, said material having a Wet Barrier Hydrostatic Head value greater than or equal to 5 cm, said possible barriers being prepared by thermobonding or hydroentanglement process. 31. Disposable absorbent article according to claim 30, characterized in that the topsheet is constituted by a material comprising cotton fibers having an average dtex value between 1 and 5, preferably subjected to a previous hydrophobic treatment, and said possible barriers consist of a material comprising cotton fibers having an average dtex value between 1 and 5, previously subjected to a hydrophobic treatment. 32. Disposable absorbent article according to claim 30, characterized in that it has a percentage by weight of cotton comprised between 5 and 100%, preferably 100%, a grammage comprised between 10 and 100 g / m <2 >, preferably between 25 and 60 g / m <2> and an average dtex value of the cotton fibers between 1.2 and 3.5. 33. Disposable absorbent article according to claim 30, characterized in that the cotton fiber has an average dtex value equal to 3. 34. Disposable absorbent article according to claim 1, characterized in that the topsheet consists of 30% cotton treated with 3 g of hydrophobic additive per 100 g of cotton fibers, and 70% polypropylene, this material having been prepared by means of a thermobonding process, having a variable weight from 14 to 26 g / m <2> and an average dtex value of the cotton fibers equal to 1.2. 35. Disposable absorbent article according to claim 1, characterized by. fact that the topsheet is made of 100% treated cotton, obtained with 3 g of hydrophobic additive per 100 g of cotton fiber, this material having been prepared through a hydroentanglement process, having a variable weight from 25 to 60 g / m and an average dtex value of the cotton fibers equal to 1.2. 36. Disposable absorbent article according to claim 1, characterized in that the spillage barriers consist of 30% treated cotton, obtained with 15 g of hydrophobic additive per 100 g of cotton fibers and 70% of polypropylene fibers, prepared through a thermobonding process and having a variable weight from 15 to 30 g / m <2>. 37. Disposable absorbent article according to claim 1, characterized in that the spillage barriers are made of 100% treated cotton, obtained with 20 g of hydrophobic additive per 100 g of cotton fibers, prepared by a process of hydroentanglement and having a variable weight from 25 to 35 g / m <2>. 38. Disposable absorbent article according to claim 1, characterized in that the topsheet consists of 30% cotton fibers with an average dtex value equal to 3, and 70% polypropylene, this material having been prepared through the thermobonding process, and having a weight of 22 g / m <2>. 39. Disposable absorbent article according to one of the preceding claims 1-38 for use as a baby diaper. Disposable absorbent article according to one of claims 1-38 for use as a sanitary napkin or panty liner. Disposable absorbent article according to one of claims 1-38 for use as a diaper or sanitary napkin for adult incontinence. 42. Disposable absorbent article according to one of claims 1-38 for use as an absorbent product for milk loss during lactation (breast pads). 43. Disposable absorbent article as described and illustrated above and for the indicated purposes.