RU2375081C1 - Adsorbing product, including hydrophilic and hydrophobic sections - Google Patents

Abstract

FIELD: textile fabrics, paper.

SUBSTANCE: present invention is related to medicine, specifically to adsorbing product, such as nappy, diaper, sanitary pad for underclothing, sanitary napkin or pad for protection against enuresis, in which at least one part of such adsorbing product has pattern with at least one hydrophilic and at least one hydrophobic sections, in which mentioned at least one hydrophilic section and/or mentioned at least one hydrophobic section are available in the form of coating on mentioned part of adsorbing product. Part with coating mainly represents liquid-permeable coating layer.

EFFECT: product produces beneficial effect, such as feeling from material, liquid absorption, healthy climate inside adsorbing product.

23 cl

Description

The present invention relates to an absorbent article, such as a diaper, diaper, underwear pad, sanitary napkin, urinary incontinence pad or the like, in which at least one part of such an absorbent article has a pattern with hydrophilic and hydrophobic portions .

BACKGROUND

Absorbent articles of this kind often include a liquid permeable cover layer facing the wearer's body, a liquid impermeable cover layer (back layer) facing the garment, and an adsorbent layer located between the liquid permeable top layer and the liquid impermeable back layer.

Typically, non-woven and perforated film materials are used as top layers. Both materials are typically obtained from initially hydrophobic synthetic polymers such as polyethylene or polypropylene.

Hydrophobic materials almost do not have the ability to adsorb body fluids on their surface, so after passing through such liquids and absorbing them with an adsorbing layer, the surface of hydrophobic materials leaves their user with a rather pleasant feeling of dryness. Since hydrophobic materials often have insufficient wettability, they are treated with moisturizing agents, for example surfactants, in order to enhance their contact with water and liquid permeability. However, due to their ability to bind water, hydrophilic materials tend to leave an unwanted sensation of moisture after the body has released fluids.

Thus, completely hydrophilic or hydrophobic materials are not able to satisfy the conflicting needs of the user of the absorbent article. Such materials for the most part do not allow the use of their useful properties in necessary cases. Moreover, it is believed that neither fully hydrophobic nor fully hydrophilic materials contribute to a healthy climate in the absorbent product. A healthy climate means, in particular, an environment with low humidity, in which, despite body fluids or sweat, the user's skin is not exposed to hyperhydration, which is one of the most common causes of diaper rash.

In addition, nanoscalar films of self-forming polymers are known from various technical fields and have attracted considerable interest in recent years. Such nanoscalar films are usually obtained by alternating deposition of monomolecular layers of two polymers containing functional groups capable of interacting with each other. Layer deposition (also abbreviated as LBL deposition) of cationic and anionic polymers based on the change in surface charge after each deposition was mainly studied, with poly (styrene sulfonate) / (polyallylamine hydrochloride) (PSS / PAH) being the most studied system.

US 2005/0069950 A1 describes a method for producing thin films, coatings, and microcapsules based on a suitable oligopeptide structure. Drug delivery is described in connection with microcapsules. Moreover, among the many possible uses of peptides with a structure according to this document, single diapers are mentioned.

US 5807636, US 5700559 and US 5837377 relate to a hydrophilic product intended for use in aqueous media and comprising a substrate, an ionic polymer layer of the aforementioned substrate and a disordered polyelectrolyte coating bonded by ions to the aforementioned polymer layer. Diapers and other pads are mentioned in these documents as one of many potential uses.

WO 00/32702 describes, for example, paper or a non-woven product containing fibers, filler particles or other particles obtained by layer-by-layer deposition of two interacting polymers, preferably anionic and cationic polyelectrolytes, commonly used as agents for imparting strength to paper in dry and wet condition. Accordingly, this document also indicates the tensile strength of the paper product.

Further documents related to LBL technology include, for example, WO 2005/058199 A1, US 5208111, US 5518767, US 5536573, US 6114099, US 6451871, US 6492096, US 2003/152703, US 2004/0086709, WO 2005/032512 , US 2004/0137039, “A. A. Antipov et al., Sustained Release Properties of Polyelectrolyte Multilayer Capsules; J. Phys. Chem. B 2001, 105, 2281-2284 ”; “M. Freemantle, Polyelectolyte Multilayers; Science & Technology (2002), 44-48 "; US 2004/0047979 A1; US 5885753 and WO 2004/07677 A2.

There is also a document related to the multilayer design of diapers without communication with LVL. WO 2005/023536 describes an absorbent article comprising at least one first portion of a microlayer film having a liquid absorption function; at least one second portion of the microlayer film having a function of absorption and distribution of the liquid; at least one third portion of the microlayer film having a liquid retention function, and at least one fourth portion of the microlayer film having a liquid protection function. Such first, second, third and fourth sections of the microlayer film are subjected to joint extrusion and assembled together, obtaining a single microlayer film system. However, it is obvious that such layers have a thickness exceeding the nm range and are not collected on their own.

In view of the foregoing, an object of the present invention is to provide an absorbent article in which the disadvantages of using fully hydrophobic or fully hydrophilic materials are eliminated in whole or in part.

One of the following technical objectives of the present invention is a more efficient use of the hydrophilic and hydrophobic properties of materials.

One of the further technical objectives of the present invention is the development of an absorbent product, certain parts of which have a beneficial effect on at least one corresponding property, such as sensation from the material, liquid absorption, healthy climate inside the absorbent product, or the like.

SUMMARY OF THE PRESENT INVENTION

The present invention relates to an absorbent article, such as a diaper, diaper, underwear pad, sanitary napkin or urinary incontinence pad, in which at least one portion of the absorbent article has a pattern with hydrophilic and hydrophobic portions, wherein at least at least one hydrophilic region and / or said at least one hydrophobic region are present in the form of a coating on said part of the absorbent article.

According to the present invention, it was found that the disadvantages of fully hydrophilic or hydrophobic materials can be overcome or reduced by coating parts of the absorbent article to cover hydrophilic and hydrophobic regions, in particular its pattern. This allows you to use the properties of hydrophilic and hydrophobic materials in an economical way, especially because hydrophilic and hydrophobic sites can be localized in the most useful place for the user. As often happens in absorbent articles, hydrophilic sites are able to condense and absorb water droplets from a humid atmosphere, while hydrophobic sites can reduce the unpleasant wet sensation often associated with completely hydrophilic materials.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention relates to an absorbent article, such as a diaper, diaper, underwear pad, sanitary napkin or urinary incontinence pad, in which at least one portion thereof has a pattern with at least one hydrophilic and at least one hydrophobic a site, wherein said at least one hydrophilic site and / or said at least one hydrophobic site are present as a coating on said part of the absorbent article.

The coating may cover the entire surface of the treated portion of the absorbent article or only a portion thereof. Hydrophilic and hydrophobic sites are located in the form of a picture.

The term “drawing” in this description means the intentional arrangement of elements on the surface in such a way that neither the hydrophilic nor the hydrophobic region / regions cover the entire surface. The pattern can be geometric or repeating, or both. The pattern may be right or wrong, with the previous one being preferred. The pattern may include at least one hydrophilic and more than one (for example, at least 2, at least 5, at least 10, at least 50, etc.) hydrophobic sections or at least one hydrophobic and more than one (for example, at least 2, at least 5, at least 10, at least 50, etc.) hydrophilic sites.

The ratio of the specific areas of coverage of the hydrophilic and hydrophobic site / sites is not specifically limited and may, for example, be from 1/99 to 99/1, from 5/95 to 95/5, from 10/90 to 90/10 or from 20/80 up to 80/20.

The term “hydrophobic”, in accordance with this technical field, is preferably understood to mean a material or part of a molecule consisting of a specific material which, when wetted with water only on a smooth, even surface consisting of such a material, forms contact angles of a fixed droplet of more than 90 °. Conversely, a smooth, even surface (where no phenomena occur due to surface roughness), leading to the formation of contact angles of a stationary water droplet of less than 90 °, or where a water droplet spontaneously spreads over the surface, is usually considered “hydrophilic”. The contact angle can be determined in accordance with the TAPPI method T558PM-95 (1995), taking into account the following.

1. Before measurement, the test materials must be acclimatized at a temperature of 23 ° C, 50% relative humidity, for a suitable period of time (at least 4 hours). Measurement should be carried out in a room with a controlled climate (temperature 23 ° C, relative humidity - 50%).

2. The test materials should be in the form of a single layer, which can be attached to a standard sample holder using double-sided adhesive tape, for example, according to the manufacturer's recommendations.

3. Suitable parameters for measurement are:

a) liquid water brand "reagent",

b) a droplet volume of 5 μl,

c) the number of measured drops to average the results: 25,

d) in a hypothetical case where neither T558RM-95 nor these indications correspond to specific measurement conditions, standard values recommended by the manufacturer of the test equipment can be used. The names of the suppliers of the corresponding test equipment are indicated in the list of random estimates for the description of the TAPPI test methods or can be obtained from the TAPPI information center. Preferred instruments are manufactured by Fibro System AB, Stockholm, under the trademark FibroDat®, such as a FibroDat 1100 contact angle measuring device.

4. Measurement of materials (for example, hydrophilic, adsorbent materials), the contact angle of which changes over time, is carried out 0.05 s after the precipitation of the droplet.

5. The measurement of the contact angle of highly hydrophobic surfaces may be unsuccessful due to the folding of droplets and their rolling from the test surface. Such surfaces are considered superhydrophobic.

By an absorbent article is meant articles capable of adsorbing body fluids, such as urine, watery feces, female secretions or menstrual fluids. Such absorbent articles include, but are not limited to, diapers, diapers, panty liners, sanitary napkins, or urinary incontinence pads.

Such absorbent articles include a liquid-permeable coating layer (top layer) that faces the user's body during use. They also include a liquid impervious cover layer (back layer), for example a plastic film, a plastic non-woven or hydrophobic non-woven material and, as a rule, but not always, an adsorbent layer located between the liquid permeable front upper layer and the liquid impermeable rear upper layer. In some absorbent articles without an absorbent layer, such as specific underwear pads sold by this applicant under various trademarks in connection with the product name “Freshness everyday”, the absorbent capacity of the front upper layer and the rear upper layer is sufficient to absorb small amounts of female secretions.

According to one preferred embodiment of the present invention, the portion comprising at least one hydrophilic and at least one hydrophobic region is a liquid permeable coating layer.

Between the absorbent layer and the top layer, at least one additional layer of a web or foam is optionally located. Such at least one additional layer may, for example,

- be combined with the top layer to obtain a multilayer top layer,

- to facilitate the removal of body fluids penetrating through the front upper layer and / or the distribution of incoming body fluids throughout the surface of the absorbent layer, as is the case in the so-called “receiving / distributing layers”, or

- be included in the wrapper of the Central part of the absorbent layer.

A suitable top layer can be made from a wide variety of materials, such as woven and non-woven materials (eg, non-woven fabric from fibers), polymeric materials, such as perforated plastic films, for example perforated molded thermoplastic films and hydroformed thermoplastic films; porous foams; reticulated foams; reticulated thermoplastic foams and thermoplastic canvases. Suitable woven and nonwoven materials can be formed from natural fibers or from a combination of natural and synthetic fibers. Examples of suitable synthetic fibers, wholly or partially constituting the top layer, include, but are not limited to, polyamide (e.g., nylon), acrylic (e.g., polyacrylonitrile), aromatic polyamide (e.g., aramid), polyolefin (e.g., polyethylene and polypropylene), polyester, butadiene-styrene block copolymers, natural rubber, latex, spandex (polyurethane), and combinations thereof. Synthetic fibers containing more than one type of repeating units can be obtained by combining repeating units at the molecular level within each macromolecular strand (copolymer), between macromolecular strands (mixture of homopolymers), or a combination thereof (mixture of copolymers); or they can be obtained by combining repeating units at a higher level with various nanoscopic, microscopic or macroscopic phases (for example, multicomponent fibers). Each component of a multicomponent fiber may include a homopolymer, copolymer, or mixtures thereof. Bicomponent fibers are common variants of multicomponent fibers. Two or more kinds of repeating units in the copolymer may be randomly arranged or in the form of alternating blocks of each type. Blocks of various types of repeating units can be connected to each other at their respective ends (block copolymers) or to the corresponding end of at least one block (grafted copolymers).

Non-woven materials can be obtained by direct extrusion methods, during which the fibers and non-woven materials are formed approximately simultaneously, or using preformed fibers, which can be laid in non-woven materials at a completely different time. Illustrative direct extrusion methods include, but are not limited to, torsion bonding, melt blasting, solvent molding, electrospinning, and combinations thereof, typically with layer molding. Illustrative “styling” processes include wet styling and dry styling. Exemplary dry laying processes include, but are not limited to, air laying, cording, and combinations thereof, typically with layer formation. Combinations of the above methods provide non-woven materials, commonly called hybrids or composites.

Fibers in a nonwoven fabric are typically connected to one or more adjacent fibers at some places of overlapping intersections. Such a process involves bonding fibers within each layer and bonding fibers between layers in the presence of more than one layer. Fibers can be joined by mechanical weaving, chemical bonding, or a combination of these methods. A more detailed description of suitable materials for the front top layer, applicable in the present invention and referred to here by reference, is given in US 2004/0158214 A1, namely in the paragraphs from [0043] to [0051].

According to this invention, it is preferable to use perforated plastic films (for example, thermoplastic films) or non-woven materials based on synthetic fibers, while the preferred materials are polyolefins, for example, homo- or copolymers of polyethylene or polypropylene and polymer compositions containing them, preferably, as the main component based on weight.

If present, said at least one additional layer positioned between the absorbent layer and the topsheet may be manufactured from a hydrophobic or hydrophilic webs or foams. By "web material" is meant coherent flat structures based on fiber from a woven or non-woven paper tissue type. Non-woven materials may have the same distinguishing features as those described above for the upper layers.

In particular, at least one additional layer may facilitate handling of the fluid, for example, in the form of at least one absorbent (receiving) / distribution layer. Such structures are described, for example, in US 5558655, EP 0640330 A1, EP 0631768 A1 or WO 95/01147.

"Foamed materials" are also well known in the art and are described, for example, in EP 0878481 A1 or EP 1217978 A1 in the name of this applicant.

The absorbent layer, which may be partially or completely surrounded by a wrapper for the central part, may include any absorbent material that is generally compressible, adherent, non-irritating to the wearer's skin and capable of adsorbing and retaining fluids, such as urine and other body exudates.

The absorbent layer may include a wide variety of liquid absorbent materials commonly used in disposable diapers and other absorbent articles, such as pulverized wood pulp, commonly called airfelt or paper dust. Examples of other suitable adsorbent materials include creped cellulose wool packing; meltblown polymers, including co-formed, chemically tightened, modified or cross-linked cellulose fibers; fabric, including wraps for fabrics and fabric laminates, absorbent foams, absorbent sponges, superabsorbent polymers (such as superabsorbent fibers), absorbent gelling materials, or any other known absorbent materials or combinations of materials. Examples of certain combinations of suitable adsorbent materials include paper dust with absorbent gelling materials and / or superabsorbent polymers, and absorbent gelling materials and superabsorbent fibers, etc.

The backing layer prevents contamination of exudates adsorbed by the adsorbent layer and contained in the article of other external articles that may be in contact with the absorbent article, such as bedding and underwear. In preferred embodiments, the backsheet is substantially impervious to liquids (e.g. urine) and includes a laminate of non-woven and thin plastic film, such as a thermoplastic film, having a thickness of from about 0.012 mm to 0.051 mm. Suitable backing films include films manufactured by Tredegar Industries Inc., Terre Haute, Ind. and sold under the trademarks X15306, X10962 and X10964. Other suitable materials for the backsheet may include “breathable” materials that allow vapors to escape from the absorbent article and yet prevent exudates from passing through the backsheet. Examples of breathable materials may include materials such as woven webs, non-woven webs, composite materials such as film-coated non-woven webs, and microporous films.

According to one embodiment of the present invention, the hydrophobic region (s) is elevated (s) relative to the plane of the hydrophilic region (s). Conversely, in accordance with this embodiment, the hydrophilic site (s) can be considered as a recess (s) relative to the plane of the hydrophobic site (s). This arrangement is obtained as a result of, for example, polymer-on-polymer embossing described below, containing sections of hydrophobic molecules or the formation of hydrophobic columns.

As also described below, the opposite arrangement, i.e. a hydrophilic site (s) elevated relative to the plane of the hydrophobic sites is found, for example, in the presence of so-called “hydrophobic columns”.

It is understood that the expression “pattern of hydrophilic and hydrophobic sites” also includes the option of having one continuous hydrophilic site (“sea”) surrounding the pattern (“islands”) of hydrophobic sites, and vice versa. Accordingly, there are also no specific limitations regarding the shape and size of such hydrophobic and hydrophilic sites. Their preferred options are described below.

According to one embodiment of the present invention, a correct pattern is formed. According to a further aspect of this embodiment, the hydrophobic regions form elevations relative to the plane of the hydrophilic regions, and vice versa.

The hydrophilic or hydrophobic regions may take any suitable shape, for example circles, squares, rectangles, ovals or stripes. As mentioned above, there are also no specific restrictions regarding their size, which may, for example, be from 100 nm ² to 10 cm ² , or in accordance with further options from 1 μm ² to 1 cm ² , from 10 μm ² to 1 mm ² or from 100 μm ² to 10,000 μm ² . The last three ranges may specifically refer to “islands” in the “sea-island” structure.

In accordance with one preferred embodiment of the present invention, at least one hydrophilic region comprising at least a portion of the hydrophilic regions, preferably at least 5%, preferably at least 20%, in particular at least 50% (for example, at least 70% or at least 90%) of all hydrophilic sites, has / have a size of less than 1 mm, preferably a diameter (e.g. circles) of less than 100 μm, more preferably a diameter of less than 20 μm, even more preferably less than 10 μm, at particularly less than 5 microns. One possible lower limit is 100 nm. If there are regular polygons (for example, squares, pentagons, etc.), “diameter” means the distance from one end to the opposite end or corner, in the presence of other shapes (for example, stripes, etc.) - the smallest axis (width ) According to one preferred alternative, the foregoing relates to “at least one hydrophobic site”.

The small size of the hydrophilic sites contribute to the absorption of water droplets by hydrophilic sites. Very effective absorption was, for example, described in US 2004/0086709 A1 (PT Hammond) and H. Yiang, H. Zheng, S. Gourdin and P. T. Hammond in “Polymer-on-Polymer stamping:“ Universal approaches to chemically patterned surfaces ”in Langmuir 2002, 18, 2607-2615”, regarding the condensation of water droplets on round hydrophilic portions of a polyamide surface having a diameter of 10 μm.

In accordance with one embodiment of the present invention, the hydrophilic regions have a diameter (e.g., circles) of 100 nm to less than 1 nm, e.g., 1 μm to less than 100 μm. If there are regular polygons (for example, squares, pentagons, etc.), “diameter” means the distance from one end to the opposite end or corner, in the presence of other shapes (for example, stripes, etc.) - the smallest axis (width )

According to one embodiment of the present invention, the hydrophilic regions form regular shapes (islands, for example, circles) surrounded by one continuous hydrophobic region (sea), which is preferably elevated relative to the plane of the hydrophilic regions. In them, the hydrophilic sites may have the above sizes.

Preferred features of all uses of the terms “drawing”, “at least one hydrophilic site” or “at least one hydrophobic site”, or synonyms thereof, are described in the previous paragraphs in this description or claims.

According to one embodiment of the present invention, the portion of the absorbent article including the pattern is a perforated front top layer (for example, a plastic film or non-woven material) having a regular pattern of perforations in which at least one part of the hydrophilic portions, preferably most of all hydrophilic sections are formed in accordance with said openings.

Hydrophilic regions preferably surround or enclose perforations. In accordance with this embodiment, the condensation of water droplets can be localized in those areas of the coating layer that allow the fluid released by the body to penetrate into the layers below the coating layer, including the adsorbing layer. Accordingly, according to this embodiment, not only more efficient removal of moisture from the skin of the user towards the absorbent article is provided. The passage of body fluids through the perforations of the upper layer material is also ensured. Similarly, the hydrophilic sites may take the form of several bands covering at least a portion, preferably a large portion, of the perforation holes of the film materials of the upper layer, in order to enhance and direct the flow of body fluids. Similarly, when using nonwoven materials as upper layer materials, it is also preferable to form hydrophilic regions on parts having higher porosity or, if any, perforations.

The hydrophilic sites are preferably formed by hydrogen donor / acceptor polymers (a polymer including a hydrogen bonded donor and / or a polymer including a hydrogen bonded acceptor) or polyelectrolyte polymers (polyanionic and / or polycationic polymer). Both systems are preferably self-forming and are preferably based on alternating (usually monomolecular) layers.

Hydrophilic sections (e.g., multilayers with alternating polymers) have a thickness in the nanometer range, i.e. less than 1 micron. The hydrophilic coating preferably has a thickness of less than 250 nm, more preferably less than 100 nm, even more preferably less than 50 nm (for example, less than 20 nm). The measurement is carried out at a relative humidity of 50% at a temperature of 20 ° C, after the film thickness reaches equilibrium under these conditions.

It is preferable to obtain multilayers (for example, hydrogen donor / acceptor or polyelectrolyte type) consisting of two or more layers, more preferably from 3 to 100 layers, in particular from 4 to 50 layers (for example, from 5 to 20 layers).

Hydrogen donor / acceptor or polyelectrolyte multilayers are preferably formed by the method of layer-by-layer (LBL) deposition, well known in the field of the formation of multilayer thin films (see references mentioned in the section “Background” or “G. Decher and JB Schlenoff (ed), Multilayer Thin Films, Sequential Assembly of Nanocomposite Materials, Wiley VCH 2003 ”, incorporated by reference).

In one embodiment (hydrogen donor / acceptor polymers), one polymer used is a neutral polymer including a hydrogen bonded donor (“hydrogen bonded polymer donor”) and preferably combined with a second (excellent) neutral polymer including a hydrogen acceptor (“ hydrogen-coupled polymer acceptor ”), in self-forming alternating layers (usually monomolecular layers).

Hydrogen bonded donors are residues containing at least one hydrogen atom capable of participating in the formation of the hydrogen bond, and a more electronegative atom bonded to the hydrogen atom. Examples of such residues include, but are not limited to, O — H, N — H, R — H, and S — H. The C — H moiety may also be a hydrogen bonded donor if the carbon atom is linked to other atoms by a triple bond, if the carbon atom is linked by a double bond to O, or if the carbon atom is bound to at least two atoms selected from O, F, Cl and Br.

Hydrogen-bonded acceptors are residues containing a more electronegative atom than hydrogen, which may also contain one pair of electrons. Examples of such atoms include, but are not limited to, N, O, F, Cl, Br, I, S, and P.

The hydrogen bonded polymer donor is preferably selected from polycarboxylic acid such as polyacrylic acid (PAA) or polymethacrylic acid, polynucleotide, vinyl nucleic acid polymer, polyamino acids such as polyglutamic acid and poly (E-N-carbobenzoxy-L-lysine), and polyalcohols such as poly (vinyl alcohol) and their copolymer.

Preferred examples of the hydrogen bonded acceptor include polyester, polyketone, polyaldehyde, polyacrylamide, other polyamides, polyamine, polyurethane, polyester, polyphosphazine or polysaccharide, or a copolymer thereof. Specific examples include polyethylene oxide, poly-1,2-dimethoxyethylene, poly (vinyl methyl ether), poly (vinylbenzo-18-corona-6), polyvinyl butyral, poly (N-vinyl-2-pyrrolidone), polyacrylamide (PAAm), polymethacrylamide , poly (N-isopropylacrylamide), poly (4-amine) styrene, poly (cyclohexane-1,4-dimethylene terephthalate), polyhydroxymethyl acryl, poly (bis (methylamino) phosphazine), poly (bis (methoxyethoxyethoxy) phosphazine, carboxymethyl cellulose or their copolymer.

One preferred combination of hydrogen donor / acceptor polymers is PAA / PAAm.

Such polymers are precipitated from aqueous solutions under conditions known in the art. Hydrogen-bonded polymer donors that perform acidic functions, such as PAA, must be precipitated under conditions (usually acidic) under which the acid groups are in non-ionized form and are therefore available for the formation of hydrogen bonds. Similarly, hydrogen acceptor polymers must be precipitated under pH conditions in which the hydrogen acceptor is in a non-ionized form. This should also be considered when choosing the appropriate combination of a hydrogen bonded polymer donor and a hydrogen bonded acceptor polymer.

Hydrophilic coatings (patches), including donor polymers and hydrogen bonded acceptor polymers, in particular polymers containing acidic groups (e.g. COOH), tend to dissolve at neutral and higher pH values. Thus, depending on the location in the absorbent article and its purpose, cross-linking of such an article may be preferable.

Crosslinking can be accomplished by simply heating the multilayer. In this case, a suitable temperature (for example, from 60 to 100 ° C) and duration depend on the chemical nature of the treated part of the absorbent article. Thermal crosslinking is preferred if functional groups (for example, the functionality of a hydrogen donor and / or hydrogen acceptor) are able to form bonds during the evolution of water, as in carboxy or amide groups. The crosslinking process is not limited to the formation of bonds between different polymers, but can likewise occur in a single layer containing, for example, carboxy groups. The heat treatment of the PAA / PAAm layers at a temperature of 90 ° C for 8 hours (or shorter periods of time at higher temperatures) leads, for example, to the formation of anhydride and amide bonds.

Crosslinking can also be carried out by chemical methods. Suitable crosslinking agents may be selected by one skilled in the art after determining functional groups (e.g., a donor and / or hydrogen bonded acceptor) present in the hydrophilic coating. As described in WO 2001/015649, multivalent metal ions can, for example, facilitate cross-linking of carboxy groups. Divinyl sulfone (DVS) is suitable for crosslinking polysaccharide-based polymers such as cellulose or starch derivatives.

Hydrophilic sites can also be formed by a polyelectrolyte monolayer, preferably a multilayer. They can also be crosslinked under the conditions described above. The multilayers are preferably formed by layer-by-layer (LBL) deposition of polycationic and polyanionic polymers. The procedure for applying such polymers to a portion of an absorbent article is not limited. Separate layers are usually monomolecular. After the entire accessible surface is covered with a monomolecular layer, repulsive charges prevent the precipitation of further molecules of the same type of polyelectrolyte.

In accordance with the LBL method, the term “layer” does not mean in the strict sense a material zone having exclusively two-dimensional extent and strict boundaries with an adjacent layer. The measurements showed that the layers deposited by the LBL method have some distribution, for example, up to seven times the average layer thickness (preferably up to 4 times). In other words, one polymer layer can penetrate into adjacent layers.

However, the layered structure of such nanoscalar films and their thickness can be confirmed by various analytical methods, including X-ray / visual spectroscopy, ellipsometry, QCM (quartz microbalance), X-ray reflectometry, neutron reflectometry, atomic microscopy in situ (AFM), surface strength measurements and others described in “G. Decher and J. B. Schlenoff, Multilayer Thin Films. ” The preferred method for determining film thickness is ellipsometry.

The hydrophilic regions obtained by layer-by-layer deposition, in particular electrolyte-based regions, form a strong, preferably durable hydrophilic coating on hydrophobic materials such as non-woven materials or hydrophobic films or foams. Since the materials used for LBL films adhere strongly to the surface, they hardly or do not dissolve in body fluids. This prevents their capture by body fluids during their passage to the absorbent layer. Conversely, low molecular weight surfactants commonly used to hydrophilize diaper materials dissolve in body fluids and tend to decrease the surface tension of body fluids, thereby reducing the absorbency of the absorbent article. In addition, only small amounts of material are required to form the film, ensuring that important characteristics, such as softness, flexibility, porosity or absorbency, are not adversely affected. A thickness of less than 1 μm provides the formation of hydrophilic sections with the necessary flexibility, repeating the movement of the underlying substrate. The LBL method used in the present invention is also most suitable for treating irregular surfaces, such as fiber surfaces, which are often found in absorbent articles. An additional advantage of LBL technology, especially if non-crosslinked polyelectrolyte polymers with different charges are used, is the ability of self-forming polymers to form new bonds by rearrangement upon bond breaking, for example, due to mechanical stress. If, for example, small cracks or pores occur in the LBL film as a result of mechanical forces, such defective sites can be repaired after the mechanical forces cease to function and polymers with interacting functional groups are not nearby again. The advantage of LBL technology is also that it is based on water and allows film coatings to be obtained without the use of potentially hazardous organic solvents.

The polymers used for LBL deposition preferably have a weight average molecular weight of at least 10,000, preferably at least 50,000, in particular at least 100,000 (for example, determined by light scattering). In general, higher molecular weights are likely to contribute to LBL precipitation. There is no specific upper limit regarding molecular weight, although in view of the desirable use of a fully water-based coating technology, the polymers preferably remain soluble in water.

For LBL deposition, weak or strong electrolytes can be used. In strong electrolytes, such as polystyrenesulfonate, ionization is complete or almost complete and does not change significantly with pH. In weak electrolytes, such as polyacrylic acid, the charge density can be adjusted by changing the pH. Weak polyelectrolytes typically have _pKa values of about 2 to 10 (the measurement is carried out at 20 ° C using an aqueous solution of 1 wt.% Polyelectrolyte containing in addition 5mmol NaCl). Such values for the RAA and RAS, for example, are about 5 and 9, respectively. Such polyelectrolytes can be homopolymers or copolymers in which only a certain percentage (for example, at least 50 mol% or less than 50 mol%) of all polymer-forming units contain a cationic or anionic group (even if this is not always mentioned below with In the description of the starting materials, anionic groups in polyanionic polymers contain an appropriate number of positive counterions, for example, hydrogen atoms and / or metal atoms, and / or onium groups (for example, ammonium) for neutral reasons Moreover, the main groups are considered cationic groups, even when, strictly speaking, the addition of protic acid is required to obtain a cationic charge, respectively, deposition must occur under pH conditions, in which the anionic and cationic charge are accessible for interlayer binding ) Polyelectrolytes can also be selected from biologically active polymers (DNA, RNA, proteins, oligo- or polypeptides, enzymes, etc.), despite the fact that, most likely, multilayers of polyelectrolytes that do not include such polymers are preferred.

Preferred polycationic polymers are selected from homo- or copolymers of at least one monomer comprising a functional group containing a protonating nitrogen atom. They may have linear or branched structures.

Cationic polyelectrolytes can be selected from:

a) cationic or cationic modified polysaccharides, such as cationic starch derivatives, cellulose derivatives, pectin, galactoglucomannan, chitin, chitosan or alginate;

b) a polyallylamine homo- or copolymer optionally containing modifying units (suitable polyallylamine modifying units are known, for example, from WO 00/31150), in particular polyallylamine hydrochloride (RAS);

c) polyethyleneimine (PEI);

d) a homo- or copolymer of polyvinylamine, optionally including modifying units;

f) a homo- or copolymer of poly (vinyl pyridine) or poly (vinyl pyridinium salts), including their N-alkyl derivatives;

f) a homo- or copolymer of polyvinylpyrrolidone, polydiallyl dialkyl, such as poly (N, N-diallyl-N, N-di-C ₁ -C ₄ alkylammonium halide) described in US 2004/0047979 A1, in particular (N chloride , N-diallyl-N, N-dimethylammonium) (PDDA);

g) a homo- or copolymer of quaternized acrylate or di-C ₁ -C ₄ -alkylaminoethyl methacrylate, for example, a poly (2-hydroxy-3-methacryloylpropyl-tri-C ₁ -C ₂ -alkylammonium salt homopolymer) such as poly (2-hydroxy-3-methacryloylpropyl trimethylammonium chloride), or a quaternized poly (2-dimethylaminoethyl methacrylate), or a quaternized poly (vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate);

h) poly (vinylbenzyl-tri-C ₁ -C ₄ -alkylammonium salts), for example poly (vinylbenzyl-tri-methylammonium chloride);

i) polymers formed by the reaction between ditretic amines or secondary amines and dihaloalkanes, including a polymer of an aliphatic or araliphatic dihalo and an aliphatic N, N, N ', N'-tetra-C ₁ -C ₄ -alkyl-alkylenediamine, for example (a) propylene-1,3-dichloride or -dibromide, or p-xylylene dichloride or dibromide, and (b) N, N, N ', N'-tetramethyl-1,4-tetramethylenediamine;

j) POLYQUAD® described in EP-A-456467; or

k) a polyaminoamide (PAMAM), for example, linear PAMAM or a PAMAM dendrimer, such as an amine-ending PAMAM dendrimer Starburst ^™ (Aldrich);

l) cationic homo- or copolymers of acrylamide and their modified products, such as poly (acrylamide-co-diallyldimethylammonium chloride) or glyoxal-acrylamide resins;

m) polymers formed by the polymerization of N- (dialkylaminoalkyl) acrylamide monomers;

n) condensation products between dicyandiamides, formaldehyde and ammonium salts;

o) conventional wet strength agents used in the manufacture of paper, such as carbamide formaldehyde resins, melamine formaldehyde resins, polyvinylamine, polyureide formaldehyde resins, glyoxalacrylamide resins and cationic materials obtained by reacting polyalkylene polyamines with polysaccharides such as starch and various starch as well as 3-hydroxyazetidinium ion-containing resins obtained by the interaction of nitrogen-containing compounds (for example, ammonia, primary and orichnogo amine or N-containing polymers) with epichlorohydrine such as polyaminoamide-epichlorohydrin resins, polyamine-epichlorohydrin resins and amine-epichlorohydrin resins, mentioned for example in US 3,998,690.

Preferred polycationic polymers are cationic or cationically modified polysaccharides, such as starch or cellulose derivatives, chitin, chitosan or alginate, homo- or copolymers of polyallylamine, homo- or copolymers of polyvinylamine or polyethyleneamine.

Examples of suitable polyanionic polymers include, for example, a synthetic polymer, a biopolymer or a modified biopolymer, or a modified biopolymer comprising carboxy, sulfo, sulfato, phosphono or phosphate groups, or a mixture thereof, or a salt thereof. They may have linear or branched structures.

Examples of synthetic polyanionic polymers are linear polyacrylic acid (PAA), branched polyacrylic acid, polymethacrylic acid (PMA), a copolymer of polyacrylic acid or polymethacrylic acid, a linear or branched polycyanoacrylate, a copolymer of maleic or fumaric acid, a polyamide acid, a diamino dihydroxy acid or a polycarboxylic acid (e.g., PAMAM dendrimers with a Starburst ^™ carboxy terminus from Aldrich). Examples of branched polyacrylic acid include the Carbophil® or Carbopol® brand from Goodrich Corp. Examples of a copolymer of acrylic or methacrylic acid include a copolymerization product of acrylic or methacrylic acid with a vinyl monomer, including, for example, acrylamide, N-dimethylacrylamide or N-vinylpyrrolidone.

Examples of polymers with sulfo or sulfate groups are poly (anetholsulfonic acid), poly (vinyl sulfate) (PVS), poly (vinyl sulfonic acid), poly (2-acrylamido-2-methylpropanesulfonic acid) (poly- (AMPS)) or poly (styrenesulfonic acid) (e.g., sodium poly (styrene sulfonate) (PSS), and examples with phosphate or phosphonate groups include alkylene polyphosphate, alkylene polyphosphonate, carbohydrate polyphosphate or carbohydrate polyphosphonate (e.g. teichoic acid).

Examples of polyanionic biopolymers or modified biopolymers are hyaluronic acid, glucosaminoglucans such as heparin or chondroitin sulfate, fucoidan, polyaspartic acid, polyglutamic acid, carboxymethyl cellulose, carboxymethyl dextrans, alginates, pectin carboxymethoxy carboxymethanes, gelitols, carboxymethyloxy carboxymethanes and gel

One of the further classes of polyanionic polymers, partially coinciding with the above-described polymers, are polymers, often used as agents, imparting strength in the dry state and used in the manufacture of paper. These include polycarboxylic acids and anhydrides such as anionic starch derivatives; polymers and copolymers obtained using (meth) acrylic acid; copolymers obtained using maleic anhydride; vinyl copolymers of carboxylic acids and anionic cellulose derivatives. Further examples thereof include polyacrylates, polymeric acrylates, polymers of maleic anhydride-vinyl acetate, copolymers of polyvinylmethyl ether-maleic anhydride, copolymers of methacrylic acid-acrylic amide, copolymers of isopropenyl acetate-maleic anhydride, copolymers of itaconic acid-maleol-alidene-vinylidene-alolide-vinylacetate-maleolide-alolide-vinyl acetate-copolymers of itaconylideryl-methylidene-alolide-vinylacetate-vinylacetate of maleic acid , copolymers of styrene-maleic anhydride, copolymers of methyl methacrylate-maleic anhydride, copolymers of acrylic acid-styrene, carboxymethyl cellulose, complex s half esters of succinic acid cellulose, graft polymerised polyacrylate copolymers polysaccharide, half esters of starch and oxidation products of the above polysaccharides. Carboxyalkylated polysaccharides include carboxymethyl cellulose (CMC), carboxymethyl hydrocellulose (SMNES), carboxymethyl hydroxypropyl cellulose (SMNRS), carboxymethyl guar and alkali metal or carob bean gum, carob bean, and carob bean.

Polyanionic polymers are preferably selected from homo- and copolymers of (meth) acrylic acid and anionic or anionically modified polysaccharides, such as derivatives of anionic starch or cellulose, such as SMS.

By choosing the appropriate combinations (and concentrations) of polycationic and polyanionic polymers prior to the deposition, the interaction of potential candidates can be tested in solution if both components of the film are soluble in the same solvent. If both solutions are mixed and flocculation occurs, this is a good sign that a multilayer is possible. Like a chemical reaction, the exact structure of each layer depends on a set of control parameters known to a person skilled in the art, such as concentration, pH, adsorption duration, ion concentration or temperature, however, in general, the processing range is quite wide.

One of the methods for producing LBL films includes the following steps in the following order:

(i) contacting the substrate (e.g., the treated portion of the diaper) with a first aqueous solution of a polyanionic or polycationic polymer, followed by removal of said first aqueous solution,

(ii) optionally washing said portion of the absorbent article with water,

(iii) contacting said portion of the absorbent article with a second aqueous solution of a polyionic polymer having an opposite charge with respect to the polymer used in step (i), followed by removal of said second aqueous solution,

(iv) optionally washing said portion of the absorbent article with water,

(v) optionally forming at least one alternating layer in a similar manner.

In this case, the term “contact” includes all known coating methods. Such methods include applying the aqueous solution by spraying, printing, using a roller, and preferably by dipping the substrate in an aqueous solution.

By “aqueous solution” is meant solutions containing water as a basic solvent by volume, preferably in an amount of more than 50% vol. The aqueous solution may also contain water-miscible organic solvents, such as water-miscible alcohols (e.g. methanol or ethanol), ethers (e.g. THF) or ketones (e.g. acetone). The inclusion of organic solvents can be used to control the deposition of the polymer polyelectrolyte and, as a result, the thickness of the layer. Under certain conditions, mixtures containing not more than 50% vol. water and at least one water miscible solvent. To minimize the swelling tendency of the LBL film, it is most likely preferable to precipitate aqueous layers from aqueous solutions that do not contain additional ingredients, with a possible exception being water-soluble salts such as NaCl.

There are no specific restrictions on the concentration of the polyelectrolyte in the first aqueous solution and the second aqueous solution. Such a concentration preferably ranges from 0.001 to 5 g / l, in particular from 0.01 to 0.5 g / l.

The deposition of layers can be carried out in a relatively wide temperature range, despite the fact that for convenience, the formation of the film is usually carried out at room temperature.

Similar steps and conditions can be used for the LBL deposition of hydrogen donor and acceptor polymers. However, it may be necessary to carry out the optimal washing step with an aqueous solution having a suitable pH instead of water.

In order to enhance the attachment of the LBL film to hydrophobic diaper materials, such as front upper layers, it may be preferable to treat them with a primer and / or carry out a surface modification step. It is preferable to use primers, the degree of adhesion of which to hydrophobic materials is known to be high, but which can simultaneously be used in LBL technology. Primers of this type can be appropriately selected by a person skilled in the art and include, for example, polyethyleneimine (PEI) or polyallylamine (RAS) providing a positive surface charge.

Preferred surface modification methods include high energy treatment. Such high energy treatment includes, but is not limited to, corona treatment, plasma treatment (preferably in air), UV irradiation, ion beam treatment, electron beam treatment, and combinations thereof. Plasma or corona treatments are described, for example, in WO 99/001099 and are capable of providing an oxygen / carbon molar ratio of greater than 0.19. Both methods increase the hydrophilicity of nonwoven or film surfaces. Plasma-treated materials suitable for use as liquid-permeable upper upper layers are also described in US 4,734,494 and WO 94/28568, EP 0483858 A1 and US 4351784. Since most treatments, including corona and plasma treatment, tend to be introduced negatively charged groups to the surface, in the next LBL deposition, it is preferable to use polycationic polymers as the first layer.

According to one embodiment, the selected regions of the pattern of the hydrophobic surface to be treated are subjected to the above-mentioned high-energy treatment (any part of the absorbent article, in particular its front upper layer). For this, an electrically conductive masking material can be used to protect parts of the hydrophobic surface from high energy treatment. More than one electrode, rotating electrodes, or intermittent switching of the electrodes may also be used to create patterns of areas with varying degrees of coverage as a result of processing. One suitable method, for example, is known from US 6,250,250 B1. In accordance with this embodiment, the pattern of hydrophobic and hydrophilic sites can be obtained by selective deposition (for example, LBL deposition of hydrogen polymer donors and / or acceptors or variable polyelectrolytes) on the processed high energy areas. This deposition method is preferably used to produce hydrophilic sites, while the hydrophobic sites correspond to those parts of the hydrophobic surface that have not been modified by high energy treatment. As for suitable deposition methods and other distinguishing features of hydrophilic sites (polymer types, size, thickness, etc.), they are described in other sections of the present invention.

According to one embodiment (A) of the present invention, at least one hydrophobic region is present as a partial coating on the hydrophilic coating. The hydrophilic coating preferably covers the entire machined surface of the part (for example, the front top layer) of the absorbent article. Thus, it is a continuous and coherent coating. The area or areas of the hydrophilic coating, not covered by a hydrophobic area (s) and, thus, remaining unprotected, form “at least one hydrophilic area”. At least one hydrophilic site has the above distinguishing features.

In embodiment (A) and other embodiments of the present invention, a hydrophobic site / sites can be obtained by applying to the hydrophilic coating polymer molecules containing at least one part of the hydrophobic molecules and at least one functional group capable of interacting with said hydrophilic coating. As described above, such a hydrophilic coating may consist of polymers containing a hydrogen donor and / or acceptor group, or, preferably, a coating of a polyelectrolyte multilayer.

In one embodiment, at least one hydrophobic region is formed by at least one hydrophobic segment of the block copolymer. Such a block copolymer, depending on the nature of the uppermost layer of the underlying hydrophilic coating, preferably also includes at least one hydrophilic segment containing a cationic or anionic group, or a hydrogen donor and / or acceptor group. The block copolymer may be a diblock or a multiblock. As described above in connection with the formation of hydrophilic sites and LBL technology, the hydrophilic segment is preferably based on the polymer segment of a polycationic or polyanionic polymer. Namely, the hydrophilic segment is preferably obtained by polymerization of at least one ethylenically unsaturated monomer comprising a cationic or anionic group of the type of group constituting the polycationic or polyanionic polymers already described. As just a few non-limiting examples, the cationic ethylenically unsaturated monomer may be selected from allylamine, vinylamine, vinylpyridine, alkylaminoethyl (meth) acrylate, acrylamide and their derivatives and salts. Non-limiting examples of an anionic group monomer are (meth) acrylic acid, maleic or fumaric acid, monomers with sulfo or sulfate groups such as vinyl sulfate, vinyl sulfonic acid, styrene sulfonic acid, styrene sulfonate, etc.

Hydrophobic segments are preferably derived from ethylenically unsaturated monomers that do not bear polar, in particular ionic functionality, such as olefins (ethylene, propylene, etc.), aromatic vinyl compounds, such as styrene or other monomers consisting of C and N.

In one embodiment, the block copolymer is a polystyrene block copolymer of (PS) -polyacrylic acid (PAA), in particular a diblock copolymer.

It seems that there are no specific restrictions on the molecular weight of the block copolymer. Higher molecular weights can enhance precipitation, but decrease solubility in known solvents. For example, a weight average molecular weight of 10,000 to 500,000 can be selected. The weight ratio of hydrophobic and hydrophilic segments can be adjusted according to the desired degree of hydrophilicity. In general, it is probably preferable to use a higher weight proportion of hydrophobic segments, in particular a ratio of more than 5/1 or even 10/1.

One suitable block copolymer for forming hydrophobic sites has been described in the aforementioned references to Paula T. Hammond: a polystyrene-poly (acrylic acid) diblock copolymer manufactured by Polysource, Inc., US, wherein the PS block has Mw = 66500, and the PAA block has Mw = 4500.

Instead of the described block copolymer, a grafted polymer may be used, including a main hydrophobic chain, onto which at least one hydrophilic side chain, including a cationic or anionic group, or, alternatively, a hydrogen donor or acceptor group, is grafted. In such grafted copolymers, the backbone is preferably formed by polymerizing a monomer having two or more ethylenically unsaturated units, but not a polar, in particular non-ionic group, such as butadiene. As mentioned above, the monomer preferably consists of carbon and hydrogen as constituent elements. The amount of unsaturated units remaining can be controlled by partial hydrogenation.

Hydrophilic side chains are grafted onto the remaining unsaturated units, polymerizing an ethylenically unsaturated monomer containing an anionic or cationic group, or, alternatively, a hydrogen donor or acceptor group. Suitable examples of anionic or cationic monomers or hydrogen donor / acceptor groups are the same as those described above.

In one aspect of Embodiment (A), at least one hydrophobic region can be applied to the underlying hydrophilic coating by a suitable printing method, such as ink jet printing, roller printing, or contact printing. If desired, microcontact printing can be used to process small areas to form very accurate patterns with micrometer or nanometer accuracy. Details regarding suitable printing methods are described in “Multilayer thin films” published by G. Decher and J. B. Schlenoff (ibid).

More preferably, in embodiment (A), at least one hydrophobic region can be obtained by stamping a layer of

(i) the aforementioned block copolymer having at least one hydrophobic segment and at least one hydrophilic segment containing a cationic or anionic group, or

(ii) the aforementioned grafted polymer comprising a hydrophobic backbone, a chain onto which at least one hydrophilic side chain containing a cationic or anionic group is grafted, or

on an electrolyte multilayer containing as an upper layer a polyelectrolyte polymer having an opposite charge with respect to the hydrophilic segment or hydrophilic side chain.

The above method is well known in the art as a type of stamping "polymer-on-polymer" and described for example in the previously mentioned references to Paula T. Hammond, as well US 2003/0152703 A1 (Paula T. Hammond et al.) And X. Jiang and PT Hammond. “Selective deposition in layer-by-layer assembly: Functional graft copolymers as molecular templates”, Langmuir 2000, 16, 8501-8509, and “G. Decher and JB Schlenoff ”(ibid, p. 282-299, and references cited therein).

The stamp used to apply the polymer forming hydrophobic sites (hereinafter abbreviated as “hydrophobic polymer”) has a three-dimensional structured surface on which the raised portions are arranged in the form of a pattern corresponding to the pattern of the obtained hydrophobic sites. Such dies can be made by methods known in the art, for example by coating a silicone master model, on which the desired pattern is etched with suitable polysiloxanes, such as PDMS (poly (dimethylsiloxane), for example, Sylguard 184 silicone elastomer kit, a commercial two-component curable siloxane).

A general polymer-on-polymer stamping technique is shown in FIG. 7 US 2004/0086709 A1. With regard to the specific conditions for the deposition of a hydrophobic polymer, such as a block copolymer of PS-b-PAA, on a polyelectrolyte multilayer or a single layer, they are presented in the description of this document, in particular in example 2, incorporated herein by reference. PS-b-PAA can be used to ink-print unprocessed PDMS dies after dissolving the polymer in a suitable organic solvent, such as THF. For other hydrophobic polymers, one of skill in the art can readily determine suitable solvents and a suitable concentration of polymer in such a solvent. After evaporation of the solvent, the stamp is preferably dried, for example, in a stream of nitrogen, and then it is contacted with the substrate, i.e. part of a diaper having a hydrophilic polyelectrolyte coating.

A wide range of stamping times, lasting, for example, from a second to an hour, can provide the desired result. It was found that the optimum stamping time for specific systems tested by Paula T. Hammond is between 10 and 15 minutes. Moreover, references from the book of P. T. Hammond show how stamping conditions, including solvent for a portable hydrophobic polymer, polymer concentration, stamping duration, etc. can be adjusted and stamping efficiency checked for optimal results. Although PT Hammond studied only polymer-on-polymer stamping of a hydrophobic block copolymer comprising carboxylic acid functionality on polyelectrolyte layers having an amine-based polyelectrolyte as the top (or sole) layer, the interaction between hydrophobic polymers containing other ionic groups and hydrophilic layers including other functionalities with an opposite charge in the upper (or single) layer will lead to the same strong electrostatic interaction, which ensures hydrophobic polymer transfer.

Depending on the size of the hydrophobic areas applied, other printing methods, such as ink jet printing or roller printing, can also be used to apply the above-described (ampiphilic) copolymer containing a hydrophobic segment, or a (ampiphilic) grafted hydrophobic copolymer containing a hydrophobic backbone.

According to one embodiment of the invention, one or more columns of an additional polyelectrolyte multilayer are deposited on a hydrophilic portion (s) remaining after stamping polymer-on-polymer or using other printing methods. Such deposition of hydrophilic “columns” of polyelectrolyte multilayers was, for example, described in the references to R. T. Hammond (et al.) Already mentioned, for example in FIG. 1 US 2003/0152703 A1. Such an additional polyelectrolyte multilayer may have the same chemical composition as the underlying polyelectrolyte multilayer, although this is not essential. As regards the description of such hydrophilic columns (chemical composition, deposition conditions, etc.), reference may be made to the above explanations regarding the underlying polyelectrolyte multilayer. The total number of layers and the total thickness of the column of the polyelectrolyte multilayer and the underlying polyelectrolyte multilayer preferably also satisfy the previously described conditions. The columns are preferably in the form of “hydrophilic islands / hydrophobic sea”.

The resulting surfaces capture droplets of water well. In particular, it is assumed that the very small sizes of the hydrophilic columns act as follows. In accordance with this embodiment of the present invention, the hydrophilic columns have a diameter (for example, circles or squares) of not more than 1 μm, preferably less than 100 nm (the lower limit may be 10 nm or less). The space between the columns is not particularly limited and may, for example, vary from more than 1 μm to several or one nm. After the droplet is formed, it begins to grow as a result of the condensation of more water vapor from the moist atmosphere of an absorbent article, such as a diaper. At some point, the drop will become too large to hold onto the hydrophilic column, and roll down onto the surrounding hydrophobic surface, from which it can easily drain into the lower layer (s) of the absorbent product, such as an adsorbent layer. For example, a perforated film can be used as a substrate (top layer) so that the liquid can reach the diaper even if the top layer is hydrophobic at the base. Thus, the above surfaces are able to remove water vapor from the air, thereby creating a more comfortable climate in the diaper.

According to one of the further options, one or more columns of a hydrophobic polymer are deposited on a hydrophobic section (s) obtained by stamping polymer-on-polymer.

The resulting surfaces cause a very dry skin sensation.

The aforementioned embodiments of the present invention are particularly suitable for sheet-like or film-like parts of an absorbent article having relatively smooth surfaces, such as perforated films, for which polymer-on-polymer stamping can be used most efficiently.

According to Embodiment (B) of the present invention, a coating on a part (for example, the top layer) of an absorbent article is formed by at least one hydrophobic or at least one hydrophilic region. Accordingly, such a coating does not cover the entire surface of said part and forms a pattern itself. Therefore, the term “coating” does not imply a mandatory primer treatment of said portion of the absorbent article.

According to a first aspect of embodiment (B) , at least one hydrophilic region forms a pattern on the hydrophobic part of the absorbent article.

In accordance with this aspect of embodiment (B), any hydrophobic part of the absorbent article, for example, upper layers formed of hydrophobic materials, is preferably subjected to the above-mentioned high-energy surface treatment before at least one hydrophilic region is applied to it. The purpose of this high-energy surface treatment is to strengthen the fixation of the hydrophilic portion (partial coating) on the underlying hydrophobic part of the absorbent article.

Two methods are generally used to perform high energy surface treatment, such as corona treatment or plasma treatment. Initially, surface treatment with high energy is carried out under conditions leading to the temporary occurrence of (negative) charges on a hydrophobic surface. Then, the printing methods described above are applied to apply a pattern of at least one hydrophilic region to a charged surface. For example, microcontact printing, in particular polymer-on-polymer stamping, can also be used to obtain a pattern of at least one hydrophilic region, in particular a polyelectrolyte pattern. Details are again described in “Multilayer thin films” published by G. Decher and J. B. Schlenoff (Ibid), for example, in the paragraph starting on page 146 and the references contained in this paragraph. At places of a hydrophobic surface that do not have a hydrophilic site (s), negative charges tend to dissipate after some time, while the surface partially or completely returns to its original hydrophobic state.

Alternatively, as described above, a high-energy surface treatment is applied to a pattern. In this case, there is no need to use specific printing methods. Hydrophilic sites can be selectively linked to sites subjected to high energy treatment. Moreover, the surface of the hydrophobic part (for example, the front top layer) can be pretreated by drawing a pattern from a suitable primer, such as PEI or RAS.

Regardless of the type of pretreatment, it is preferred that at least one hydrophilic region is formed by a polyelectrolyte layer, in particular a polyelectrolyte multilayer. Such a polyelectrolyte multilayer can preferably be obtained by layer-by-layer (LBL) deposition of at least one polycationic and polyanionic polymer. In this regard, the above description of the LBL deposition may be mentioned with respect to suitable deposition conditions, the electrolytes used and its other distinguishing features.

The above paragraph describes methods for selectively applying a pattern of at least one hydrophilic region to the hydrophobic parts of an absorbent article. Selective dissolution of a continuous hydrophilic coating can also be used to achieve this goal. Such dissolution is described in more detail below.

Accordingly, any hydrophobic part of the absorbent article, for example, a top layer made of a hydrophobic material, is optionally subjected to the above-described high energy surface treatment or primer treatment. A continuous hydrophilic coating is then formed, preferably LBL, by precipitation of hydrogen donor polymers and / or acceptors or polyelectrolytes, i.e. polyanionic and / or polycationic polymers. Such a hydrophilic coating can be formed under the conditions described previously and preferably has the above distinguishing features. The hydrophilic coating preferably includes any of the above hydrogen acceptor polymers and a hydrogen polymer donor comprising an acid group. Such hydrogen donor polymers can be selected from the above classes of polymers, with polyacrylic acid and polymethacrylic acid being preferred. Such hydrogen donor polymers and hydrogen acceptor polymers are precipitated under acidic conditions in which the hydrogen donor groups are present in non-ionized form and are therefore available for the formation of hydrogen bonds. When using PAA and PAAm, the pH of both the dipping solution and the washing solution, for example, is adjusted to 3.0 with aqueous HCl, without adding salt to the solution.

In the next step, the pattern of selected areas is treated by contacting the hydrophilic coating with water or an aqueous solution, preferably an aqueous buffered solution, having a higher pH than the pH at which precipitation occurs (the difference is preferably at least 1.5 pH units, preferably at least three pH units). Preferred pH values of the aqueous solution vary, for example, from 4.5 to 9, in particular from 6 to 8. The PAA / PAAm multilayers dissolve, for example, quickly in aqueous solutions having a pH of 4.5 or more, or even faster in phosphate buffer solutions having a pH = 7.0. Ink-jet printing is suitable for accurately applying such a pattern from an aqueous solution, in particular an aqueous buffered solution. Details are described in the book “Multilayer thin films” published by G. Decher and J. B. Schlenoff (Ibid), for example, in the paragraph starting on page 144, as well as in the references cited therein. In FIG. 5.11 on p. 150 of this book additionally schematically presents such a process of subtractive ink-jet printing.

After inkjet printing, the hydrophilic coating is dried and crosslinked, preferably using the aforementioned thermal crosslinking process. Since the aqueous (buffered) solution ionizes the hydrogen donor groups, such as carboxy groups, remain intact and are subject to crosslinking.

In the next step, the non-crosslinked (i.e., printed) sections of the coating can be washed off with water, thereby exposing the hydrophobic surface of the coated part (for example, the top layer) of the absorbent article.

With regard to suitable hydrophobic materials, reference may be made to the above description of materials for the top layer, including polymer classes described in connection with synthetic fibers. Preferred hydrophobic materials are polyolefins, such as homo- or copolymers of polyethylene or polypropylene and polymer compositions containing them, preferably as the main weight component.

According to a second aspect of embodiment (B) , at least one hydrophobic portion forms a pattern on the hydrophilic portion of the absorbent article.

The hydrophilic part may, for example, be a top layer or a layer between an absorbent layer and an upper layer (“at least one additional layer”) made from natural fibers, in particular cellulose fibers present in the cellulosic pulp. Alternatively, the hydrophobic materials described above in connection with the upper layers are subjected to hydrophilization before drawing a pattern of hydrophobic sites.

Suitable hydrophilizing treatments include applying surfactants or the previously mentioned primer treatment. The at least one hydrophobic pattern forming region is preferably applied by one of the aforementioned printing methods. At least one hydrophobic site is preferably formed by at least one hydrophobic segment of a block copolymer or grafted polymer comprising a hydrophobic backbone. For this purpose, block copolymers or grafted polymers described above in connection with polymer-on-polymer stamping can be used.

It should be noted that, wherever the distinguishing features (materials, conditions, uses, etc.) are not called “preferred” in this description, the description of this application also includes a combination of at least two of the distinguishing features provided that they Do not contradict each other.

MORE PREFERRED OPTIONS

The present invention is further illustrated by more preferred variants of its implementation. The above options reflect a combination of distinctive features that can preferably be used to implement the present invention.

OPTION 1

The top layer (for example, a polyethylene nonwoven material or a perforated film) or a similar portion of an absorbent article, such as a diaper, is optionally treated with a corona or plasma to obtain temporary negative charges. Such a treatment can be subjected to the entire upper layer or part of the upper layer (wetting zone, middle third of the upper layer, etc.). Optionally, the processed polyethylene non-woven material or film is immersed in PEI and PAA solutions (or sprayed, printed, using a roller) to form alternating self-forming layers of PEI (polyethyleneimine) and PAA (polyacrylic acid). At least one, preferably at least two, layers are applied. If necessary, a washing step may be carried out between the coating steps to remove excess polymer. Alternatively, polyallylamine hydrochloride (RAS) or any other amine-based polymer may be used in place of PEI. The coating process is completed by precipitation of a PEI or polyamine layer.

A hydrophobic pattern is then obtained by stamping a polymer-on-polymer type of a suitable block copolymer, for example, PAA-PS onto PEI or a polyamine surface. The resulting surface is capable of absorbing water droplets in a hydrophilic region.

OPTION 2

Hydrophilic columns can be formed on the surface with the pattern obtained in embodiment 1 by further deposition of the polyelectrolyte multilayer on hydrophilic sites. For this purpose, the polyanionic and polycationic polymers described above in connection with the LBL technology and the corresponding deposition conditions can be used.

The resulting surfaces capture water droplets that roll onto the surface well when they become large enough. Moreover, such surfaces are able to remove water vapor from the air, thereby creating a more comfortable climate in the diaper. In this case, a perforated film can be used as a substrate so that liquid can penetrate the diaper even when the front top layer is hydrophobic at its base.

OPTION 3

A hydrophobic substrate, such as a polyolefin-based nonwoven fabric or a perforated film used as the top layer, is optionally subjected to high energy surface treatment (e.g. corona discharge) to produce (negative) surface charges. For processing with high energy, it is preferable to choose such conditions so that they can provide temporary formation of negative charges.

A positively charged polymer, preferably one of the aforementioned polycationic polymers, is applied by printing in the form of a desired pattern. The preferred printing method is inkjet printing for small prints, providing high accuracy, while other printing methods, such as printing using a roller, can be used for larger designs. To obtain very small patterns, microcontact printing (polymer-on-polymer stamping) can be used. After precipitation of the polycationic polymer from its aqueous solution, the substrate is optionally washed with water.

If desired, a second polymer layer having an opposite charge, i.e. polyanionic polymer, applied by dipping the substrate in its aqueous solution, or by spraying, using a roller, etc. The polyanionic polymer adheres only to printed areas.

The resulting substrate with a polyelectrolyte double layer pattern is optionally washed again with water. Such a deposition cycle can be repeated to obtain additional layers.

When carrying out additional deposition cycles, it is desirable to wait for the dissipation of negative charges on the hydrophilic substrate until the substrate contacts again with solutions of polycationic polymers.

Other hydrophobic substrates, such as perfluorinated film materials based on polyolefins, can be obtained in a similar manner.

OPTION 4 (SELECTIVE DISSOLUTION AND CROSS-LINKING)

The hydrophobic substrate illustrated in Embodiment 3 is optionally subjected to a high energy surface treatment, such as a corona discharge treatment, to obtain negative surface charges.

The substrate is immersed over and over again in aqueous solutions of poly (acrylic) acid and poly (acrylamide), the pH of which has been adjusted to 3 with hydrochloric acid, to obtain alternating layers of PAA and PAAm. The resulting layers may optionally be washed with a dilute hydrochloric acid solution to remove excess polymer.

After applying the desired number of layers, the selected removed portions are contacted with an aqueous solution / water having a pH of greater than 3.0. Neutral water or a buffer (e.g., phosphate buffer) having a pH of 7 is preferably used. In principle, depending on the size of the areas to be removed, contact with the aqueous solution / water and removal to the next crosslinking step can be combined in one step, for example using a focused stream of water.

However, it is usually preferable to first dry and crosslink the coating. Crosslinking can be carried out thermally by heating the coated substrate to a temperature of 90 ° C for at least 8 hours. During such a crosslinking step, only those areas of the coating that did not come in contact with water are capable of undergoing crosslinking chemical reactions, such as the formation of anhydride or imide bonds.

Then, the coating is washed with water to remove areas that have not undergone cross-linking that previously had contact with water, thereby exposing the underlying hydrophobic substrate. In this way, a pattern may be formed comprising at least one hydrophilic and hydrophobic region. As for the details of this method, they are described in the book “Multilayer thin films” published by G. Decher and J. B. Schlenoff (Ibid), as well as in the references cited therein.

It should be noted that, despite the high-energy hydrophilizing treatment of the surface, the resulting (negative) charges on the surface tend to dissipate during aging, so the surface regains or approaches its initial hydrophobic state.

OPTION 5

In the event that the treated substrate (such as hydrophilic non-woven or tissue paper) is initially hydrophilic, high-energy surface treatment is not required. Then the hydrophilic / hydrophobic pattern can be obtained by selectively applying in the form of a pattern on a continuous electrolyte multilayer coating the final layer of a suitable block polymer having at least one hydrophobic region or a grafted polymer comprising a hydrophobic backbone. Examples of a hydrophilic polymer are polymers described in connection with polymer-on-polymer stamping. It preferably includes a functional group, for example a cationic or anionic group, selectively bonded to the top polyelectrolyte polymer layer having an opposite charge.

OPTION 6 (CROWN RELIEF PROCESSING)

A (optionally perforated) polyethylene-based nonwoven fabric or a perforated film, preferably of the same type as the film used to produce the front top layer, is subjected to a high-energy surface treatment such as a corona discharge or plasma treatment to obtain a negative charge pattern on a hydrophobic surface. The pattern is preferably applied in accordance with the perforations so that the treated areas include or surround such openings.

The resulting nonwoven fabric is then alternately immersed in aqueous solutions of a suitable polycationic polymer, such as polyacrylic acid (PAA), and a polyanionic polymer, such as poly (allylamine hydrochloride) (RAS), to deposit at least two coating layers. After each immersion step, the nonwoven fabric or film is optionally washed with water. Such a deposition cycle can be repeated to form the desired number of layers. After the final immersion precipitation step, the nonwoven fabric or film is again optionally washed with water and then dried.

Claims (23)

1. An absorbent article, such as a diaper, diaper, underwear pad, sanitary napkin or pad for urinary incontinence, characterized in that at least one part of such an absorbent article contains a pattern with at least one hydrophilic and at least at least one hydrophobic region, wherein said at least one hydrophilic region and / or said at least one hydrophobic region are present in the form of a coating on said part of the absorbent article, wherein shey least one hydrophilic portion is formed polyelectrolyte layer, in particular polyelectrolyte multilayer. 2. The absorbent article of claim 1, wherein said portion is a liquid permeable coating layer. 3. The absorbent article according to claim 1 or 2, wherein said pattern is correct. 4. The absorbent article according to claim 1, wherein said at least one hydrophobic region is elevated relative to the plane of said at least one hydrophilic region. 5. The absorbent product according to claim 1 or 4, in which the hydrophilic sites are surrounded by one continuous hydrophobic site. 6. The absorbent product according to claim 5, in which the hydrophilic sections are in the form of circles. 7. The absorbent product according to claim 1, in which at least part of the hydrophilic or hydrophobic sections has a diameter of less than 100 microns. 8. The absorbent article of claim 2, wherein the portion of the absorbent article including the pattern is a perforated plastic film or non-woven material having a regular pattern with perforations, and the hydrophilic portions are applied in accordance with the perforations so that the hydrophilic portions surround or cover perforations. 9. The absorbent article according to claim 1, in which the polyelectrolyte multilayer is obtained by layer-by-layer (LBL) deposition of at least one polycationic and at least one polyanionic polymer. 10. The absorbent product according to claim 9, in which the polycationic polymer is selected from cationic or cationic modified polysaccharides, homo- or copolymers of polyallylamine, homo- or copolymers of polyvinylamines or polyethyleneimine. 11. The absorbent product according to claim 9, in which the polyanionic polymer is selected from homo- or copolymers of (meth) acrylic acid and anionic or modified with anions derived polysaccharides. 12. An absorbent article according to any one of claims 9 to 11, wherein the polymer constituting the hydrophilic region or the polymers constituting the hydrophilic region are crosslinked. 13. The absorbent article according to claim 1, in which at least one hydrophobic region is present as a partial coating on a hydrophilic coating deposited on said portion of the absorbent article, and the region or regions of the hydrophilic coating not coated with at least one hydrophobic region are formed at least one hydrophilic site. 14. The absorbent article of claim 1, wherein the at least one hydrophobic region is formed by at least one hydrophobic segment of a block copolymer or grafted polymer comprising a hydrophobic backbone. 15. The absorbent product according to claim 1, in which the pattern with at least one hydrophilic and at least one hydrophobic regions is obtained by stamping a layer (i) of a block copolymer having at least one hydrophobic segment and at least one hydrophilic segment containing a cationic or an anionic group, or (ii) a grafted polymer comprising a hydrophobic backbone onto which at least one hydrophilic side chain containing a cationic or anionic group is grafted; on a polyelectrolyte layer, in particular a multilayer, the top layer of which is a polyelectrolyte polymer layer having an opposite charge with respect to said hydrophilic segment or hydrophilic side chain. 16. The absorbent product according to item 13 or 15, in which one or more columns of the additional polyelectrolyte multilayer deposited on at least one hydrophilic site. 17. The absorbent article of claim 1, wherein the at least one hydrophilic portion forms a pattern on the hydrophobic portion of the absorbent article. 18. The absorbent article of claim 17, wherein the hydrophobic portion of the absorbent article is subjected to high energy surface treatment before applying at least one hydrophilic portion to it. 19. The absorbent article of claim 18, wherein such a high energy treatment is applied in the form of a pattern. 20. The absorbent article of claim 18, wherein the at least one hydrophilic region includes crosslinked hydrophilic polymers. 21. The absorbent article according to any one of claims 1, 2, 4, 6, 7 or 14, in which at least one hydrophobic portion forms a pattern on the hydrophilic part of the absorbent article. 22. A liquid-permeable coating layer for an absorbent article, such as a diaper, diaper, underwear pad, sanitary napkin or urinary incontinence pad, characterized in that the coating layer contains a pattern with at least one hydrophilic and at least one hydrophobic region, wherein said at least one hydrophilic region and / or said at least one hydrophobic region are present as a coating on said portion of the absorbent article, said at least one hydrophilic region is formed by a polyelectrolyte layer, in particular a polyelectrolyte multilayer. 23. The coating layer according to item 22, in which the coating is a coating, as described in any one of claims 2 to 21.