MXPA01001359A - Fibrous structure and absorbent article including such a fibrous structure - Google Patents

Abstract

A fibrous structure notably for use in hygienic articles such as diapers, sanitary napkins, incontinence guards, wipes and thelike, having one or several types of polar, silicon containing compounds bound to at least one portion of the surface of the fibrous structure by interaction between the surface and the silicon containing compounds, whereby the fibrous structure exhibits a predetermined degree of hydrophilicity and adhesion properties which are substantially unaffected by wetting of the fibrous structure. Further, the invention pertains to absorbent, hygienic and textile articles comprising such a fibrous structure.

Description

FIBROUS STRUCTURE AND ABSORBENT ARTICLE THAT INCLUDES SUCH FIBROUS STRUCTURE BACKGROUND OF THE INVENTION The present invention relates to a fibrous structure (either woven or non-woven, natural or synthetic etc.). As is well known, such fibrous structures are used in many industrial applications, such as those given hereafter by way of illustration without any limitation: hygienic articles (female as well as medical / surgical) such as diapers, sanitary napkins, protective for incontinence, cleansers, wound dressings, facial masks and the like; - industrial applications such as those used in insulation products (thermal, electrical) or filtration products, or floor coverings; - textile products. Depending on the type of fibrous structures and applications considered, the properties of hydrophilicity and / or adhesion will be sought in a particular way. Taking the example of non-woven materials, these are produced from comparatively hydrophobic synthetic fibers such as, for example, polypropylene or polyethylene fibers which are treated and / or perforated in order to make the materials permeable to liquid. In order to obtain fluid absorbent articles exhibiting a good torsional capacity, a high total and local capacity of fluid absorption, good fluid retention capacity and a high degree of surface dryness, such articles are commonly manufactured in a plurality of different fibrous non-woven structures that have different functions. However, a major problem in the construction of fluid-absorbent articles of this type is the difficulty to obtain an optimum wettability, that is, an optimum degree of hydrophilicity that remains unchanged after having exposed the article to wetting. In addition, it is difficult to obtain stable wetting characteristics in absorbent articles that have been stored for an extended period of time. In WO 91/05108, it has been experimentally shown that there is a relationship between the increased surface area and the increased absorption ratio. The patent application refers to fibers that have been provided with a porous layer adhered to the surface of the fibers. The porous layer increases the specific surface area of the fibers which implies that the absorbent material containing such fibers obtains a better absorption rate and torsional capacity.

The porous layer is created by impregnating the fibrous material with hydrophilic chemicals while the fibers are maintained in a dry or wet state in the form of dried fiber pulp or in the form of an aqueous fiber suspension, respectively. The treatment can be executed by contacting the fibers with the hydrophilic chemicals for example by spraying the fibers in an absorbent layer formed with a chemical solution or by mixing the chemicals with a fiber suspension wherein the chemicals are added as solids, in a solution, or in any commercially available form. With respect to the fluid-permeable cover sheets for use in absorbent articles such as diapers, incontinence guards and sanitary napkins, wherein the cover sheet is proposed to be in contact with a user's body during use, it is important that the cover sheet can withstand repeated wetting. In other words, the cover sheet must remain permeable to the fluid even after the absorbent article has been exposed several times to the fluid impact. In addition, it is important that the cover sheet can accept a large amount of fluid for a short period of time. Another important property of the fluid permeable cover sheet is the ability to exhibit high surface dryness even after being exposed to various wettings. In order to obtain a cover sheet that has the desired propertiesIt is important that the cover sheet exhibits an optimum degree, that is, a desired degree of hydrophilicity and that the degree of hydrophilicity varies only within a very limited range when the fibrous structure is wet or when subjected to aging. As is well known to the person skilled in the art, the literature in these fields talks about the properties of "hydrophilicity" or "wettability" of a substrate, or of "adhesion" of a third body on a substrate and frequently reports measurements of "surface tension", "contact angle" and "exfoliation test" to evaluate such properties. A method commonly used to increase the wettability of the fluid-permeable cover sheets for use as cover sheets in absorbent articles is to treat the material with surfactants. The non-woven materials used as cover sheets for absorbent articles are commonly made of synthetic materials which are inherently hydrophobic and which have been treated with surfactants in order to become wettable and easily permeable to fluids. The treatment is usually carried out by coating the hydrophobic material with a surfactant. In order for a material to be wettable with fluid, the contact angle between the surface of the material and the fluid must be less than 90 °. However, a problem with the use of cover sheets that have been coated with a surfactant is that such cover sheets exhibit a decrease in fluid permeability with repeated wetting. The reason for this is that the applied surfactants are not firmly adhered to the surface of the cover material and will come off the cover material and dissolve in the body fluid during the first wetting. In subsequent wetting the amount of surfactant that remains on the surface of the cover sheet is therefore considerably reduced, resulting in deterioration of the fluid permeability. Another problem in relation to the use of articles having cover sheets coated with surfactant is that the surfactant compounds can migrate from the cover sheet to the wearer's skin, thereby causing skin irritation. A further problem with absorbent articles having cover sheets of this type is that during storage of the article the surfactants can migrate from the cover sheet to the absorbent structure, resulting in the fluid permeability of the cover sheet being insufficient even in the first fluid impact. Still another problem with surfactant-coated cover sheets is that the method of applying the surfactant is less attractive from an environmental point of view since the surfactant is commonly applied to the surface of the material in the form of a solution which, for example, it is sprayed on the surface and causes the surfactant to be released into the ambient air. SUMMARY OF THE INVENTION The present invention provides a fibrous structure of the type mentioned in the introduction. The fibrous structure exhibits, if desired, a well defined moistening ratio, ie, a predetermined degree of hydrophilicity which is not substantially affected by wetting of the fibrous structure, and / or good adhesion properties which do not they are affected in a substantial way by the wetting of the fibrous structure. Further, with the present invention a fibrous structure is provided, wherein the predetermined degree of hydrophilicity and the desired adhesion properties are maintained even after the structure has been stored for a period of time. According to the above, the present invention offers a hygienic product having a well defined and controlled wetting course. A fibrous structure according to the invention is distinguished mainly by one or several types of polar compounds containing silicon, which are linked to at least a portion of the surface of the fibrous structure by the interaction between the surface and the silicon-containing compounds. As previously mentioned, the fibrous structure according to the invention exhibits a predetermined degree of hydrophilicity and adhesion properties that are not substantially affected by wetting the fibrous structure. According to one embodiment, the silicon-containing compound consists of a compound of the SiOxHy type wherein x is preferably in the range of 1 to 4, and preferably in the range of 0 to 4. An advantage with a fibrous structure of this type is that the wetting characteristics of the structure have proven to be substantially constant during wetting and that the fibrous structure is comparatively resistant to aging. Without being in any way limited by the following theoretical explanation of why a hydrophilic surface having silicon-containing polar compounds exhibits stable hydrophilicity and adhesion properties, both after repeated wetting and after aging of the structure of the material, one may think that the polar compounds containing silicon form a type of agglomerates that are large enough to inhibit the reorientation of the polymer chains and, accordingly, to the aging phenomenon. However, the theory is not fully developed and according to this should not be considered as linked to the invention. As already mentioned, the fibrous structures according to the invention exhibit at least one surface or portion of a surface of polar material containing silicon,. However, it is possible according to the invention to apply silicon-containing compounds to both surfaces of a sheet of material. In addition, one or both surfaces of the material may exhibit one or more delimited areas having polar compounds containing silicon. According to one aspect of the invention, the fibrous structure comprises one or more nonwoven materials. According to a further aspect of the invention, the fibrous structure of the invention can, for example, be used as a fluid permeable cover sheet for absorbent articles or as a fluid transfer layer between the fluid permeable cover sheet and the Absorbent structure in an absorbent article, or for the absorbent structure itself.

According to another aspect of the invention, the fibrous structure of the invention can be used as a cloth that absorbs liquid, or as a component in a cloth or the like. In yet another aspect of the invention, the fibrous structure may comprise one or more layers of tissue. As is well known to the person skilled in the art, the term "fabric" commonly covers the fibrous material based on cellulose or cellulose in combination with synthetic fibers and typically used in the manufacture of household items such as kitchen towels , toilet paper, or napkins, in the manufacture of industrial wipes for the absorption of different liquids, or for the manufacture of layers that enter the structure of absorbent articles such as diapers, incontinence guards, sanitary napkins or the like. Additionally, the invention relates to an absorbent article such as a diaper, an incontinence protector, a sanitary napkin or the like comprising an absorption body that is contained between a fluid impervious cover layer and a fluid permeable cover layer. , said article comprises at least one portion comprising a fibrous structure according to the invention. The fibrous structure may constitute a part or all of the pre-fluid cover layer and / or a fluid transfer layer located between the pre-fluid cover layer and the absorbent body. In a hygienic product for purposes of fluid absorption and which is made from a plurality of individual layers, the transfer of fluid between the different layers is of great importance both for the proportion of torsion in each individual layer and for the total capacity of absorption of fluid of the hygienic product. From the above discussion it appears that in fluid-absorbent articles of this type it is very important that all layers of material exhibit a stable and well-defined degree of hydrophilicity that only varies to a very limited extent with wetting and aging. According to one aspect of the invention, the liquid permeable cover sheet, the fluid transfer layer, and the absorbent body have different degrees of hydrophilicity. According to one of the preferred embodiments of the invention, the fluid transfer layer of the sanitary article comprises a set of several fibrous structures according to the invention, the set of fibrous structures has a gradient of degrees of hydrophilicity.

The invention further relates to a sanitary product such as a cloth, a wound dressing or the like, comprising a fibrous structure according to the invention. The invention further relates to a method for producing a fibrous structure having one or more types of silicon-containing polar compounds bonded to at least a portion of a surface of the fibrous structure. The method is distinguished mainly by the fact that the fibrous structure is subjected to a rrue atmosphere comprising excited and unstable species, as obtained through the application of an electric discharge to an initial mixture comprising a carrier gas, an oxidant, and at least one type of gaseous compound containing silicon. An advantage with such a method is that it is carried out under dry conditions which implies that the silicon-containing compound does not have to be dissolved in a solvent before its application, which means that the method is advantageous from one point. of environmental view. According to a preferred embodiment, the treatment is based on an electric discharge conducted in a gaseous mixture, which leads to the formation of a plasma. As is well known, a plasma is a gaseous medium that contains ions, radicals, electrons, excited and unstable species. Can be obtained through the supply to a gas mixture of a sufficient amount of energy, at a defined pressure, for example at very low pressure or atmospheric pressure. All plasma species can react with each other and / or with the components of the gas mixture to create new ions, radicals, and excited species. When carried out at atmospheric pressure with a high voltage electrical signal as an energy source, plasma is commonly referred to as "corona". According to this preferred embodiment, the fibrous structure is therefore subjected to an electric discharge, in the presence of a gaseous mixture comprising at least one type of gaseous compound containing silicon, oxygen or other gas containing oxygen, and a gas carrier. According to another embodiment of the invention, the fibrous structure is subjected to a treatment atmosphere as obtained in the post discharge of an electric discharge applied to a gas mixture comprising at least one type of gaseous compound containing silicon, oxygen or another gas containing oxygen, and a carrier gas (the fibrous structure is here subjected to the treatment atmosphere outside the discharge). In any case, the unstable and excited species in the atmosphere react with the polymer chains on the surface of the fibrous structure, leading to the formation of radicals of such polymer chains. These radicals can then react with the species present in their vicinity thus forming new bonds and new functional groups on the surface. The functional groups that are relevant to the present invention are polar groups containing silicon. The functional groups introduced in this way on the surface of the material are much more strongly bonded to the surface than the active substance which has been applied as a conventional coating. A method for the corona treatment is described in US 5,576,076, US 5,527,629 and US 5,523,124. The gas mixture is based on a carrier gas that is commonly nitrogen, a compound containing silicon and an oxidant. The treatment creates a layer of material that has a glassy, hydrophilic surface. The method described is suitable for use in connection with the invention. However, the invention is not limited to the method described in the above-mentioned applications, but comprises all kinds of gas phase treatments in which the silicon-containing polar groups are introduced to a surface of a fibrous structure. According to a preferred embodiment, the silicon-containing compound in the gas mixture is a silane compound. Some examples of such compounds are SinHn + 2 wherein n is preferably 1 to 4, silicon hydroxide, halogenated silanes, alkoxysilane or organosilane. The oxidant is preferably oxygen or other oxygen-containing gases such as, for example, CO, CO, NO, N20, or N02. The carrier gas may consist of nitrogen, argon, helium, or a mixture thereof. According to one of the embodiments of the invention, before being treated with the medium comprising unstable and excited species, which result from the application of an electric discharge to the gaseous mixture comprising the gaseous compound containing silicon, an oxidant and an Carrier gas, the fibrous structure in a first stage has been subjected to corona discharge under air (surface preparation). BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments thereof in relation to the accompanying drawings in which: Figure 1 shows a diaper seen from the side that It is proposed to be in front of the user during its use; and Figure 2 shows an instrument for measuring the contact angle for individual fibers. DETAILED DESCRIPTION OF THE INVENTION The diaper 100 shown in Figure 1 comprises a fluid permeable cover sheet 101, a fluid impermeable cover sheet 103, and an absorption body 105 contained between the cover sheets 101, 103. The fluid impermeable cover sheet 103 may consist of a fluid impermeable plastic film, a sheet of nonwoven material that has been provided with a fluid resistant coating or any other type of flexible sheet material that resists fluid penetration. Generally, it is an advantage if the fluid impermeable cover sheet 103 is aerable at least to some extent, implying that water vapor can pass through the cover sheet. The cover sheets 101, 103 have a flat extension that is somewhat larger than the flat extension of the absorption body 105 and comprise edge portions 107 projecting beyond the peripheral edge of the absorption body 105. The cover sheets 101, 103 are joined within the edge portions 107 which protrude by means of, for example, adhesives or heat welding or ultrasonically. In addition, the diaper 100 has two longitudinally extending side edges 123, 125, an end front edge 109 and a trailing end edge 111, and exhibit a front portion 113, a rear portion 115, and an intermediate crotch portion 117. which is narrower than the end portions 113, 115. In addition, the elements 119, 121 are arranged along the side edges 123, 125 in the crotch portion 117 of the diaper. The purpose of the elastic elements 119, 121 is to provide means for keeping the diaper in sealed contact around the user's legs when the diaper is in use. An additional elastic element 127 is positioned along the edge of the trailing end 111 and is provided to give the diaper 100 a certain degree of extensibility and formability and to act as sealing means against filtration at the waist. A tape tab 129, 131 is positioned to each side edge 123, 125 near the edge of the trailing end 111. The tape tabs 129, 131 constitute securing means for the diaper 100 and allow the diaper 100 to be formed as a garment of dress around the lower part of the user's body in a similar way to underpants. The tape tabs 129, 131 cooperate with a receiving area 133 located on the fluid impermeable cover sheet 103 on the front portion 113 of the diaper. The receiving area 133 can be constituted by a reinforcing material which has been laminated to the fluid impermeable cover sheet 103. By reinforcing the cover sheet the diaper 100 can be closed and reopened without affecting the adhesive properties of the tape tabs. 129, 131 or causing the rupture of the cover sheet impermeable to the fluid 103. Of course, it is possible to use any of several different alternative types of insuring elements. Some examples of such alternative securing elements are hook and loop surfaces, pressure pins, tie-down straps, or the like. The absorption body 105 commonly comprises one or more layers of cellulose fiber, such as fluffed cellulose pulp. In addition to the cellulosic fibers the absorption body 105 can comprise super absorbent material which is a material in the form of fibers, particles, granules, film or the like and which has the capacity to absorb the fluid in an amount corresponding to several times the weight of the super absorbent material itself. The super absorbent materials bind the absorbed liquid and form a gel that contains the liquid. The absorption body 105 may further comprise a binder, shape stabilizing means, or the like. It is also possible to use additional absorbent layers to improve the absorption properties, such as different types of inserts or layers of liquid dispersing material. The absorption body 105 can be chemically or mechanically treated to change the absorption characteristics. One way to improve the torsional capacity of an absorbent structure commonly employed is to provide the absorption body with a pattern of compressed areas. In addition, it is possible to use absorbent materials such as non-woven absorbent materials, absorbent foams, or the like. Similarly, all conceivable combinations of suitable absorbent materials can be used. The fluid-permeable cover layer 101 comprises one or more layers of material wherein at least one layer of material consists of a fibrous structure according to the invention. According to the invention a fibrous structure can be introduced into the structure of an upper layer 106 which during use of the diaper 100 will be in contact with the wearer's body and / or a lower fluid transfer layer 108 which is located between the upper layer 106, in contact with the skin and the absorption body 105 which is placed below the fluid-permeable cover layer 101 and / or of the absorption body 105. In case both, the upper layer in contact with the skin 106, the absorption body, and the fluid transfer layer 108 are fibrous structures according to the invention, it is advantageous that these layers mutually exhibit different degrees of hydrophilicity. This can be achieved, for example, by the use of gas mixtures of different compositions when treating the different fibrous structures. The invention is not restricted to any type of particular material. Accordingly, the choice of polymer, fiber thickness or fiber density depends on the type of article (for example absorbent article) for which the fibrous structure is proposed as well as the function and location of the fibrous structure in the article ( in search of hydrophilicity properties or for example of adhesion properties). By way of illustration, fibrous structures are commonly made of polypropylene, polyethylene, polyester, and their copolymers. However, the invention should not be restricted to these polymers. An example of another type of useful polymers are the biodegradable polymers. For the biodegradable materials to work well as a cover sheet prior to the fluid, it is usually necessary to treat the material with a hydrophilic agent or to perforate the material. As mentioned above, the usual way to achieve wettability in a fibrous sheet material is by coating the material with surfactants that are less favorable to the environment than desired. Accordingly, the present invention provides means for creating a fluid permeable cover sheet having environmentally beneficial properties both with respect to biodegradability and because the use of surfactants can be avoided. Examples of fibrous structures according to the invention are described hereinafter. Example 1 - ESCA measurements To examine the chemical composition of the surface of a material the chemical analysis was carried out by electronic spectroscopy, ESCA. At ESCA, the surface of the material is irradiated with X-rays. High-energy X-rays result in the emission of electrons from the surface of the material. The binding energy of an emitted electron is obtained from: Eb = hv - Ek Eb = the bonding energy of the electron Ek = the kinetic energy of the electron Hv = the radiation energy The energy of the X-rays is known and the Kinetic energy is obtained by measuring the speed of the electron. Accordingly, a value can be obtained for the binding energy of the emitted electron which implies that the chemical composition of the surface can be identified. Samples of example 1 la. non-woven material untreated polypropylene. 2a. non-woven polypropylene material that has been corona treated according to the invention to introduce polar groups containing silicon to the surface of the material. 2b. non-woven polypropylene material that has been washed after being treated with a crown. The operating conditions under which samples 2a and 2b were treated according to the invention are the following: Speed of the network = 26 m / min. Width of the network = 0.65 m Electric power of the crown = 1690 W N2 flow rate = 94 l / min. Flow rate of N20 = 0.39 l / min. Flow rate of SiH4 = 0.115 l / min. The network was treated here in two stages: in a first stage, treated with corona under air, and in a second stage, treated with corona with injection of the gaseous mixtures described hereinabove. When the material is washed, it is immersed in a container with distilled water. The temperature of the distilled water is 37 ° C. The material is left in the water for 15 seconds and then removed from the water and placed flat to dry. Results of example 1 - Concentration of oxygen and (%) of silicon on the surface of the material: Sample 1 2a 2b 0 0.7 '31.9 35.2 Yes 9.2 11.2 The results showed that the corona treated non-woven material according to the invention exhibits an oxygen concentration that is 31.9% and a silicon concentration that is 9.2% on the surface of the material. The oxygen and silicon concentrations are maintained even after the material has been washed as is evident from sample 2b. Example 2 - Using a set of scales of Cahn to determine the contact angle of the fiber. The Wilhelmy method was used to determine the angle of wetting of the fiber. The measurement was carried out using a set of Cahn scales 200, which is shown in Figure 2. During the measurement interval a fiber 201 is suspended vertically in an extremely sensitive set of beam scales 202. A container is placed of liquid 205 on a movable table 206 directly below the fiber 201. When the fiber 201 is immersed in the liquid 203 a half-moon of liquid is formed around the fiber, which affects the fiber 201 with a vertical force. The force arising between the liquid 203 and the fiber 201 can be either positive or negative, depending on the characteristics of the surface of the fiber and the liquid. An attractive force arises which is a positive force when the contact angle between the fiber and the liquid is less than 90 °. When the system has a contact angle that is greater than 90 °, the liquid and the fiber reject each other, which implies force. The force of attraction or rejection is determined by means of the set of beam scales. The force is related to the contact angle according to: F =? L p cos? + mg - pL lgA F = registered force (N)? L = energy of the liquid surface (J / m2) p = fiber circumference (m)? = contact angle at the fiber-liquid-air interface (°) m = installed fiber mass (Kg) g = gravitational constant (m / s2) pL = liquid density (Kg / m3) 1 = fiber length wet (m) A = cross-sectional area of the fiber (m2) The second term in the equation represents the weight of the installed fiber. The third term is what is known as hydrostatic force, which is the loss of weight that occurs as a result of the volume of liquid that is dislodged. These two parameters are commonly compensated in a computer (not shown) and equipped with a calculating program for the determination of contact angles which simplifies the equation in: F =? L p cos? The progressive contact angle and the backward contact angle specify whether the dynamic contact angle is measured when a liquid advances on a dry surface or when a liquid recedes from a wet surface. Accordingly, the value for the progressive contact angle is obtained when the fiber descends into the liquid and the value for the backward contact angle is obtained when the fiber is removed from the liquid. The set of beam scales 202 has three deposits (see Figure 2). A first tank A has an accuracy of 10"6, which makes it suitable for measuring contact angles for fibers, however, the set of scales can also be used to determine the energy of the surface for liquids where a second is used. deposit B, less sensitive The set of scales is tared by placing weights in balance in a third deposit C.

To prevent the flow of air, dust or the like from interfering with the measurement, the reservoirs and the movable table 206 are protected by sliding glass screens 207. Furthermore, the screens make it possible to control the humidity and temperature of the air. To avoid disturbing vibrations during the course of the measurement, the set of scales is placed on a base (not shown). The table on which the liquid container 205 is placed can be raised and lowered by means of a motor. The speed of the table 206 is controlled by the computer and is specified before the start of a measurement. Other parameters that are fed to the computer before starting the measurement are the surface energy of the liquid and the circumference of the fiber 210. Before starting the measurement, a fiber is installed 201 on a piece of tape 208 with a part of the fiber free from the tape. The installed fiber 201 is held by a metal clamp 209 and suspended from the first reservoir A. Before, the set of scales 202 has been tared only with the metal clamp 209 which is suspended from the first reservoir A. A test liquid 203 having a known surface energy is placed in the liquid container 205 on the table 206 below of the fiber 201. The fiber 201 must hang perpendicular to the surface of the liquid 210 and must be absolutely immobile, showing the set of scales a stable value, before starting the measurement. When a measurement is started the computer registers a baseline after table 201 rises. When one or a few millimeters of the fiber 201 have been immersed within the liquid 203, the computer is instructed to stop the table. Subsequently, table 206 descends. During the course of the test the variation of force along the fiber is displayed on the computer screen. When the measurement is completed, representative portions are selected from the progressive and regressive curves, respectively. Next, the computer calculates the contact angles using the Wilhelmy equation. The contact angle measurements were performed on individual fibers taken from a nonwoven material of 18 g / m2 consisting of polypropylene. The fibers were immersed in a liquid container with distilled water. Samples of example 2 la. Polypropylene fibers from an untreated nonwoven material; you. after storing the untreated non woven material of the. during three months; 2a. polypropylene fibers of a non-woven material that has been corona treated according to the invention to introduce polar silicon-containing groups to the surface of the material; 2b. after washing the corona treated non-woven material in 2a; 2 C. after storage for five weeks the non-woven material treated with corona in the 2nd. (not washed); 2d. after washing and subsequent storage for five weeks of the corona treated nonwoven material in the 2nd; The operating conditions under which the samples 2a, 2b, 2c and 2d were treated according to the invention were the following: Speed of the network = 26 m / min. Width of the network = 0.65 m Electric power of the crown = 1690 W N2 flow rate = 94 l / min. Flow rate of N20 = 0.39 l / min. Flow rate of SiH = 0.115 l / min. The network, in a first stage, was treated with corona under air and in a second stage, it was treated with corona with injection of the gaseous mixtures described hereinabove. When the material is washed, it is done by placing it in a container with distilled water. The temperature of the distilled water is 37 ° C. The material is left in the water for 15 seconds and then removed from the water and placed flat to dry. The contact angle is measured for individual fibers from washed non-woven material. Results of example 2 Sample contact angle (progressive / regressive) 99/93 ° le 98/90 ° 2a 50/25 ° 2b 58/31 ° 2c 50/19 ° 2d 52/23 ° The results show that the fibers of Untreated polypropylene have a contact angle greater than 90 °, which implies that such fibers are hydrophobic. The polypropylene fibers of a nonwoven material that have been corona treated according to the invention to introduce silicon-containing polar groups onto the surface of the material exhibit, on the other hand, a considerably low contact angle as shown by the results for the samples 2a-d. After washing the corona treated nonwoven material the contact angle has been changed from 50 ° to 58 ° for the progressive angle and ° to 31 ° for the regressive angle which implies that the degree of hydrophilicity is maintained at a relatively constant level after the material is washed. Sample 2c refers to fibers of the corona-treated non-woven material that has been stored for five weeks after carrying out the first and second measurements to determine the aging effect of the material. It was found that the progressive angle is 50 ° for both the fibers of the stored nonwoven material and the fibers of the nonwoven material that has not been stored. It was found that the regressive angle is 25 ° for the unsaved material and 19 ° for the material that has been stored, which implies that the degree of hydrophilicity was not affected substantially after five weeks of storage. Finally, sample 2d refers to polypropylene fibers of a corona treated nonwoven material that was washed and then stored for five weeks. The degree of hydrophilicity of the sample 2d is almost constant compared to the sample 2a not stored and not washed which indicates that the introduced polar groups containing silicon are stably bound to the fibrous surface. Example 3 - determination of the penetration time of the liquid for a sheet of material. To determine the penetration time of the liquid for the fibrous structure, the EDANA test method No. 14-20-06 W25 was used. The method measures the time required for a predetermined amount of liquid to pass through a top sheet of nonwoven material where the unwoven material is in contact with a standard absorbent material located beneath the nonwoven material. The standard absorbent material consists of five layers of filter paper, ERT FF3 100 x 100 mm. When the measurement is carried out, the filter papers are placed on a Plexiglas base plate. A non-woven sample is placed on top of the filter papers with the proposed side to face a user's skin upwards. A LISTER mark penetration plate from Lenzing AG is placed in the upper part of the sample, taking care that the penetration plate is centered. A penetration time measurement instrument is placed on top of the penetration plate with the distance between the liquid outlet tube on the penetration time measuring instrument and the 30 mm penetration plate. A test liquid of 5.0 ml was measured and emptied into the liquid container on the instrument, from here on the measurement is started. The penetration time measurement instrument is of the same brand as the penetration plate.

The measurement I carried out on a non-woven material consisting of polypropylene and having a basis weight of 18 g / m2. The test liquid was a 0.9% solution of NaCl. Samples of example 3 la. untreated polypropylene nonwoven material; 2a. non-woven polypropylene material that has been corona treated according to the invention to introduce polar groups containing silicon to the surface of the material; 2b. after washing the corona treated nonwoven material of the 2nd. The operating conditions under which samples 2a and 2b were treated were the following: Speed of the network = 26 m / min. Width of the network = 0.65 m Electric power of the crown = 1690 Flow rate of N2 = 94 l / min. Flow rate of N20 = 0.39 l / min. Flow rate of SiH = 0.115 l / min. The network, in a first stage, was treated with corona under air and in a second stage, it was treated with corona with injection of the gaseous mixtures described hereinabove. The material is washed by placing it in a container with distilled water. The temperature of the distilled water is 37 ° C. The material is left in the water for 15 seconds and then removed from the water and placed flat to dry. Results of Example 3 Sample Time (seconds) 1 >; 300 2a 2.7 2b 2.9 The results show that the untreated non-woven material exhibits a penetration time of more than 300 seconds, which implies that the liquid does not penetrate through the non-woven material during the measurement period that is 300 seconds (five minutes). The non-woven material of the sample 2b which has been corona treated according to the invention to introduce polar silicon-containing groups to the surface of the material exhibits a penetration time of 2.9 seconds which is approximately equal to the penetration time. of the non-woven material treated with non-washed crown. The invention should not be considered as restricted to the embodiments described herein. Accordingly, a plurality of further variants and modifications are conceivable within the scope of the appended claims.

Therefore, if the invention and all its advantages have been particularly described and illustrated in the case of fibrous non-woven structures used in the field of baby diapers, as will be clearly apparent to the person skilled in the art, the invention finds a much larger field of application, which includes for example woven fibrous structures, either natural or synthetic. In addition to the hygienic field, many other fields of application can be considered within the scope of the present invention, with different types of properties in each case that can be sought and achieved according to the invention (hydrophilicity, adhesion, anti-stain treatment ... ). Some of those hundreds of uses have been illustrated at the beginning of the present description.

Claims (14)

1. CLAIMS 1. An absorbent article comprising one or more fibrous structures, characterized in the following manner: a) at least a portion of the surface of at least one of the fibrous structures is bonded to at least one or more types of polar compounds that contain silicon, b) the fibrous structure (s) of paragraph a) exhibit in this manner a predetermined degree of hydrophilicity which is not substantially affected by wetting the structure, and / or exhibits (n) adhesion properties that are not substantially affected by wetting the structure. An absorbent article according to claim 1, characterized in that the silicon-containing compound is constituted mainly of a compound of the SiOxHy type wherein x is preferably in the range of 1 to 4, and and preferably is in the range from 0 to 4. 3. An absorbent article according to claim 1 or 2, characterized in that at least one of the fibrous structures comprises one or more sheets of tissue. 4. An absorbent article according to claim 1 or 2, characterized in that at least one of the fibrous structures comprises one or more non-woven materials. 5. An absorbent article according to any of claims 1 to 4, characterized in that the fibrous structure (s) bonded to a silicon-containing compound has been subjected to an electrical discharge, in the presence of a gaseous mixture comprising at least one type of gaseous compound containing silicon, oxygen or other oxygen-containing gas, and a carrier gas. 6. An absorbent article according to any of claims 1 to 4, characterized in that the fibrous structure (s) bonded to a silicon-containing compound has been subjected to an atmosphere. of treatment as obtained in the post discharge of an electric discharge applied to a gaseous mixture comprising at least one type of gaseous compound containing silicon, oxygen or other oxygen-containing gas, and a carrier gas. An absorbent article according to claim 5 or 6, characterized in that the fibrous structure (s) bonded to a silicon-containing compound, before being subjected to electric shock in the presence of the gaseous mixture, or the treatment atmosphere in the post-discharge, has been in a first stage, subjected to a corona discharge under air. An absorbent article according to one of claims 1 to 7, characterized in that it is a diaper, a sanitary napkin, an incontinence protector, or the like, since it comprises an absorbent body contained between a cover sheet impermeable to the fluid and a fluid-permeable cover sheet, and wherein the absorbent article comprises one or more fibrous structures bonded to a silicon-containing compound. 9. An absorbent article according to claim 8, characterized in that the liquid permeable cover sheet comprises one or more fibrous structures bonded to a silicon-containing compound. An absorbent article according to claim 8 or 9, characterized in that a fluid transfer layer is placed between the liquid-permeable cover sheet and the absorption body, wherein the fluid transfer layer comprises a or more fibrous structures bonded to a silicon-containing compound. 11. An absorbent article according to claim 10, characterized in that the liquid permeable cover sheet, the fluid transfer layer, and the absorption body have different degrees of hydrophilicity. 12. An absorbent article according to claim 10 or 11, characterized in that the fluid transfer layer comprises a set of several fibrous structures bonded to a silicon-containing compound, and in which the set of fibrous structures has a gradient of degrees of hydrophilicity. 13. An absorbent article according to one of claims 1 to 7, characterized in that it is a hygienic article such as a cleanser, a wound dressing, or the like and in that it comprises one or more fibrous structures bonded to a silicon-containing compound. 14. An absorbent article according to claim 13, characterized in that it comprises a set of several fibrous structures linked to a silicon-containing compound, and in which the set of fibrous structures has a gradient of degrees of hydrophilicity.