Absorbent products with improved absorption properties

Abstract

Absorption article comprising an absorption structure, wherein the absorption article is divided into three sections: a front section, a rear section and a step section located between the front section and the rear section, wherein the absorption structure comprises an absorption core, the absorption core having a dry thickness of 0.2 to 5 mm at the step point of the article, wherein one or more sections of the absorption structure comprise at least 90 wt.% superabsorbent polymer particles and require a time to uptake of 20 g / g (T20) of less than 250 s, as measured by the K(t) test method, wherein at least one of the one or more sections (30, 32, 34) of the absorption structure has a surface area of ​​30 cm2 or more.

Description

AREA OF INVENTION

[0001] The present invention relates to absorbent articles, such as disposable diapers, exercise briefs and adult incontinence underwear, comprising superabsorbent polymer particles. BACKGROUND OF THE INVENTION

[0002] Absorbent products, such as disposable diapers, training pants, and adult incontinence underwear, absorb and retain bodily fluids. Many absorbent products, like diapers, contain superabsorbent polymer material. These polymers are typically present in the core of the product in particle form. These polymer particles are able to absorb liquid and swell upon contact with fluids. However, experience has shown that not all categories of superabsorbent polymer particles are equally suitable for use in absorbent products.

[0003] In order to obtain absorbent articles that contain superabsorbent polymer particles exhibiting good absorption and retention functions, certain technical requirements must be met by the superabsorbent polymer particles.

[0004] The superabsorbent polymer particles must first be able to rapidly absorb the liquid precipitates. In the prior art, the absorption rate of superabsorbent polymer particles is characterized by measuring the free swell rate (FSR) of the particles.

[0005] In addition to a high absorption rate, the superabsorbent polymer particles present in the core must also be highly permeable to liquids. Poor permeability of the superabsorbent polymer particles can lead to leakage of the absorbent article due to gel blockage.

[0006] Gel blockage can occur in the absorbent core when swelling superabsorbent polymer particles block the spaces between them. In such a case, liquid excretions cannot reach, or can only reach slowly, the deeper layers of superabsorbent polymer particles arranged within the core. The liquid excretions remain on the surface of the absorbent core and can therefore leak from the diaper.

[0007] The permeability of superabsorbent polymer particles is typically characterized in the prior art by measuring the SFC (saline flow conductivity) of the particles. This parameter is measured under equilibrium conditions, i.e., the measurement is performed on a fully pre-swollen gel bed of superabsorbent polymer particles.

[0008] However, the inventors have now surprisingly found that absorption cores, which have superabsorbent polymer particles with high FSR and high SFC values, do not automatically lead to short uptake times for liquid precipitates into the absorption core, especially not during the first surge, i.e., when the absorption cores first come into contact with liquid.

[0009] The present invention therefore creates an absorbent article with improved absorption properties and thereby reduces leakage, especially during the first surge, i.e. when the article is first wetted. SUMMARY OF THE INVENTION

[0010] The present invention relates to an absorbent article comprising an absorbent structure. The absorbent article is divided into three sections: a front section, a back section, and a step section located between the front and back sections. The absorbent structure includes an absorbent core. The absorbent core has a dry thickness of 0.2 to 5 mm at the step point of the article. At least one section of the absorbent structure comprises at least 90 wt% superabsorbent polymer particles and requires less than 440 s to achieve an uptake of 20 g / g (T20), as measured by the K(t) test method. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. Figure 1 is a top view of a diaper according to an embodiment of the present invention.

[0012] Fig. 2 is a cross-sectional view of the in Fig.1 diaper shown along the section line 2-2 of Fig. 1,

[0013] Fig. Figure 3 is a partial cross-sectional representation of an absorption core layer according to an embodiment of the present invention.

[0014] Fig. Figure 4 is a partial cross-sectional representation of an absorption core layer according to another embodiment of the present invention.

[0015] Fig. 5a is a partial sectional view of an absorption core, which is a combination of the first and second absorption core layers, which are in Fig. 3 and Fig. The 4 are shown.

[0016] Fig. 5b is a partial sectional view of an absorption core, which is a combination of the first and second absorption core layers, which are in Fig. 3 and Fig. The 4 are shown.

[0017] Fig. Figure 6 is a schematic representation of a rheometer.

[0018] Fig. Figure 7 is a lateral partial cross-sectional view of a suitable permeability measurement system for performing the test to measure the effective dynamic permeability and uptake kinetics.

[0019] Fig. Figure 8 is a cross-sectional view of a piston / cylinder arrangement for use in performing the test of measuring the effective dynamic permeability and uptake kinetics.

[0020] Fig. 9 is a top view of a piston head designed for use in the Fig. The piston / cylinder arrangement shown in 8 is suitable.

[0021] Fig. Figure 10 is a partial cross-sectional view of a suitable permeability measurement system for performing the urine permeability measurement test.

[0022] Fig. Figure 11 is a cross-sectional view of a piston / cylinder arrangement for use in performing the urine permeability measurement test.

[0023] Fig. 12 is a top view of a piston head, designed for use in the in Fig. The piston / cylinder arrangement shown in 11 is suitable.

[0024] Fig. Figure 13 is a cross-sectional view of the piston / cylinder arrangement of Fig. 11, which has been placed on a deep-fried disc for the swelling phase.

[0025] Fig. Figure 14 shows a cross-sectional view of a suitable flat acquisition measurement system for performing the flat acquisition test or flat imaging test.

[0026] Fig. Figure 15 is a cross-sectional view of an absorption structure to be tested according to the K(t) test procedure, wherein a layer of a material that is not part of the absorption structure is removed from the absorption structure by means of a cold spray mist.

[0027] Fig.Figure 16 is a cross-sectional view of an absorption structure to be tested according to the K(t) test procedure, wherein the upper layer of the absorption structure is perforated using a perforating tip.

[0028] Fig. Figure 17 shows a top view of the perforation pattern according to which the upper or lower layer of an absorption structure can be perforated.

[0029] Fig. Figure 18A is a graphical representation showing the uptake in g / g as a function of time for the absorption structures of comparison examples 1 and 2 and of example 1, measured using the K(t) test procedure.

[0030] Fig. Figure 18B is a graphical representation showing the uptake in g / g as a function of time for the absorption structures of comparison examples 1 and 2 and of example 2, measured using the K(t) test procedure. DETAILED DESCRIPTION OF THE INVENTION

[0031] "Absorbent article" is used herein to refer to devices that absorb and retain bodily excretions, and in particular refers to devices that are placed on or near the wearer's body to absorb and retain the various excretions excreted by the body. Absorbent articles include diapers, exercise panties, adult incontinence underwear, feminine hygiene products, and the like. As used herein, the term "body fluids" or "bodily excretions" includes, among other things, urine, blood, vaginal discharge, breast milk, sweat, and feces. In some embodiments of the present invention, the absorbent article is a diaper or exercise panties.

[0032] The term "absorption core" is used herein to refer to a structure arranged between a top layer and a bottom layer of an absorbent article to absorb and retain liquid taken up by the absorbent article. The core comprises superabsorbent polymer particles. The core may include one or more carrier material layers, superabsorbent polymer particles arranged on the one or more carrier material layers, and a thermoplastic composition, usually arranged on the superabsorbent polymer particles. The thermoplastic composition is typically a thermoplastic adhesive. The thermoplastic adhesive may form a fibrous layer that is at least partially in contact with the superabsorbent polymer particles on the one or more carrier material layers and partially in contact with the one or more carrier material layers.An auxiliary adhesive can be applied to one or more carrier material layers before the superabsorbent polymer particles are applied to improve the adhesion of the superabsorbent polymer particles and / or the thermoplastic adhesive to the respective carrier material layer(s). The absorption core can also include one or more cover layers, such that the superabsorbent polymer particles are positioned between the one or more carrier material layers and the one or more cover layers. The one or more carrier material layers or cover layers can comprise or consist of a nonwoven fabric, a woven fabric, a film, or a combination thereof. The absorption core can further include odor-absorbing compounds.

[0033] The absorption core can essentially consist of one or more carrier material layers, the superabsorbent polymer particles, the thermoplastic composition, optionally the auxiliary adhesive, optionally the cover layer(s) and optionally odor-damping compounds.

[0034] The absorption core can comprise superabsorbent polymer particles arranged between two layers: an upper layer and a lower layer without superabsorbent polymer particles above the upper layer and below the lower layer. The upper layer corresponds to the support material layer or cover layer of the absorption core that is closest to the upper layer of the article, and the lower layer corresponds to the support material layer or cover layer of the absorption core that is closest to the lower layer of the absorbent article. Alternatively, the absorption core can consist of the structure arranged between the upper and lower layers without an upper layer, or the absorption core can consist of the structure arranged between the upper and lower layers without a lower layer.Without a top and bottom layer, the absorption core can correspond to the entire structure arranged between the top and bottom layers of the absorption article. The carrier material layer(s) or cover layer(s) can comprise or consist of a nonwoven fabric, a woven fabric, a film, or a combination thereof.

[0035] The term “absorption structure” is used herein to refer to one of the following structures: a. the absorption core of the absorption article in the case that the absorption core comprises superabsorbent polymer particles arranged between two layers, namely an upper layer and a lower layer without superabsorbent polymer particles above the upper layer and below the lower layer. The upper layer corresponds to the support material layer or cover layer of the absorption core that is closest to the upper layer of the article, and the lower layer corresponds to the support material layer or cover layer of the absorption core that is closest to the lower layer of the absorption article. b. the absorption core of the absorption article in combination with the top layer of the absorption article in the case that the absorption core does not have a top layer as defined above, c. the absorption core of the absorption article in combination with the sublayer of the absorption article in the case that the absorption core does not have a sublayer as defined above.

[0036] “Section of absorbing structure” is used herein to denote a section of the absorbing structure by the thickness of the absorbing structure, i.e., a section of the absorbing structure that includes all the different layers that make up the absorbing structure in that section.

[0037] The terms “front section” and “rear section” are used herein to refer to the front and rear waist regions of the absorbent article. The length of the front section and the rear section is each one-third of the total length of the article, starting at the respective front and rear waist regions. For embodiments in which the front and / or rear waist edge is not designed as a straight line parallel to the transverse centerline of the absorbent article, the length of the absorbent article is determined at or parallel to the longitudinal centerline, starting at the point on the front waist edge closest to the transverse centerline and ending at the point on the rear waist edge closest to the transverse centerline.

[0038] The term "step section" is used herein to refer to the region of the article located in the middle, between the front and back sections. The length of the step section is one-third of the article's total length.

[0039] The term “step point” is used herein to denote the point of the article that is located in the center of the absorption article at the intersection of the article’s longitudinal and transverse center lines. It should be noted that, for the purposes of the invention, the step point of the article need not necessarily be located in the center of the absorption core, i.e., at the intersection of the longitudinal and transverse center lines, particularly in the case where the absorption core is not located on the article’s transverse center line, i.e., in the case where the absorption core is shifted towards the front or back of the article.

[0040] The term "center of the front section" is used herein to denote the point of the absorbent article located at the intersection of the longitudinal centerline and the line parallel to the transverse centerline of the article, the latter being a distance from the transverse centerline equal to one-third of the total length of the absorbent article. For embodiments in which the front and / or rear waist edge is not a straight line parallel to the transverse centerline of the absorbent article, the length of the absorbent article is determined along or parallel to the longitudinal centerline by starting at the point on the front waist edge closest to the transverse centerline and ending at the point on the rear waist edge closest to the transverse centerline.

[0041] “Contain”, “comprehensive” and “encompasses” are non-exclusive expressions that also include the exclusive expressions “consist of”, “consisting of” or “consists of”.

[0042] “Airfelt” is used herein to refer to shredded wood pulp, which is a form of cellulose fiber.

[0043] The term “superabsorbent polymer particles” is used herein to refer to cross-linked polymeric materials capable of absorbing at least 10 times their weight in aqueous 0.9% saline solution, as measured by the Centrifuge Retention Capacity Test (EDANA WSP 241.2-05). The superabsorbent polymer particles are in particle form, so that they are free-flowing in the dry state. Preferred superabsorbent polymer particles of the present invention consist of poly(meth)acrylic acid polymers. However, polymer particles based, for example, on starch are also within the scope of the present invention.

[0044] “Thermoplastic adhesive material,” as used herein, refers to a polymer composition from which fibers can be formed and applied to the superabsorbent polymer particles with the aim of immobilizing the superabsorbent polymer particles in both dry and wet conditions. The thermoplastic adhesive material of the present invention preferably forms a fibrous network over the superabsorbent polymer particles.

[0045] "Nonwoven" is used herein to refer to a sheet or mat product made of oriented or randomly oriented fibers bound together by friction and / or cohesion and / or adhesion, excluding paper and products that are woven, knitted, tufted, sewn together with twine or filaments, or felted by wet milling, whether or not additionally needle-punched. The fibers may be of natural or artificial origin and may be staple or continuous fibers or formed in place.Commercially available fibers have diameters ranging from less than approximately 0.001 mm to more than approximately 0.2 mm, and they come in several different forms: short fibers (so-called staple or short fibers), continuous single fibers (filaments or monofilaments), untwisted bundles of continuous filaments (cables), and twisted bundles of continuous filaments (yarn). Nonwovens can be produced using several processes, such as meltblowing, spunbonding, solvent spinning, electrospinning, and carding. The basis weight of nonwovens is usually expressed in grams per square meter (g / m²).

[0046] The term "fastened" is used herein to describe configurations in which a first element is directly fixed to another element by directly fixing the first element to a second element, or in which a first element is indirectly fastened to a second element by fixing the first element to one or more third, interposed elements, which in turn are fixed to the second element. The fastening device may include adhesive bonds, thermal bonds, pressure bonds, ultrasonic bonds, dynamic mechanical bonds, or any other suitable fastening devices or combinations thereof known in the art.

[0047] Fig. 1 is a top view of an absorption article 10 according to embodiments of the present invention. The absorption article 10is shown in the spread-out, non-contracted state (i.e., without elastic-induced contraction) and parts of the absorption article 10 are cut away to reveal the underlying structure of the diaper 10 to demonstrate more clearly. A section of the absorption article. 10 , who comes into contact with a carrier, is in Fig. 1 shown. The absorption article 10 generally comprises a basic unit 12 and an absorption core 14 , which is in the basic unit 12 is arranged.

[0048] The basic unit 12 of the absorption article 10 in Fig. 1 can be the main body of the absorption article 10 include the basic unit 12 can an outer cover 16 include an upper class 18 , which may be permeable to liquids, and / or a sublayer 20, which can be impermeable to liquids. The absorption core 14 can be divided between the upper class 18 and the lower class 20 be included. The basic unit 12 can also side fields 22 , elasticated leg cuffs 24 and an elastic waist feature 26 exhibit.

[0049] The leg cuffs 24 and the elastic waist feature 26 Elastic band elements can usually be used individually. 28 include. A final section of the absorption article. 10 is considered the front section 30 designed, and the other end section is different from the rear section 32 of the absorption article 10 designed. The intermediate section of the absorption article 10 is as the step section 34 designed to run lengthwise between the front and rear sections 30 and 32 extends.

[0050] The absorption article 10 is in Fig. 1 with its longitudinally running center line 36 and its transverse center line 38 shown. The perimeter border 40 of the absorption article 10 is formed by the outer edges of the absorption article 10 defined, wherein the longitudinally running edges 42 generally parallel to the longitudinal center line 36 of the absorption article 10 run, and the front and back waist edges 43 and 44 between the longitudinally running edges 42 generally parallel to the transverse center line 38 of the absorption article 10 proceed. The basic unit 12 may also have a fastening system that includes at least one fastening element 46 and at least one support zone48 may include.

[0051] The absorption article 10 It may also incorporate other such features known in the art, including front and rear wing panels, waist-seal features, elastics, and the like, to provide improved fit, restraint, and aesthetic properties. Such additional features are known in the art and are described, for example, in U.S. Patent No. 3,860,003 and U.S. Patent No. 5,151,092.

[0052] To the absorption article 10 To hold onto the support, at least part of the front section can be held. 30 through the fastening element 46 at least part of the rear section 32It is attached to form a leg opening and waist of the article. Once attached, the fastening system bears a tensile load around the waist of the article. The fastening system may allow a user of the article to remove a component of the fastening system, such as the fastener. 46 , to keep and the front section 30 at least two points with the rear section 32 to connect. This can be achieved by manipulating the bond strengths between the elements of the fastening device.

[0053] According to certain embodiments, the absorption article 10It may be equipped with a resealable fastening system or, alternatively, may be provided in the form of a panty-like diaper. If the absorbent product is a diaper, it may include a resealable fastening system connected to the base unit to secure the diaper to a wearer. If the absorbent product is a panty-like diaper, the product may have at least two side panels joined together to form a panty. The absorption structure

[0054] The absorption structure comprises superabsorbent polymer particles.

[0055] One or more sections of the absorption structure comprise at least 90 wt% superabsorbent polymer particles, based on the weight of the section of the absorption structure, excluding the weight of any support material layer and / or cover layer and / or top layer and / or bottom layer that may be contained in the section of the absorption structure. The one or more support material layers or cover layers may comprise a nonwoven fabric, a woven fabric, or a film, or combinations thereof, or may consist of these as sole components.

[0056] One or more sections of the absorption structure may be centered in the middle of the front section of the article, and / or one or more of the sections of the absorption structure may be centered at the step section of the article.

[0057] One or at least one of the several sections of the absorption structure can have a surface area of ​​30 cm². 2 or more. Alternatively, one or each section can have a surface area of ​​30 cm². 2 or more.

[0058] One or at least one of the several sections of the absorption structure, which has a surface area of ​​30 cm² 2 or more, can enclose a circular area. Alternatively, one or any of the several sections of the absorption structure, which has a surface area of ​​30 cm², can be used. 2 or more, enclose a circular area.

[0059] One or more sections of the absorption structure can comprise at least 95 wt% superabsorbent polymer particles.

[0060] One or more sections of the absorption structure can comprise at least 98 wt% superabsorbent polymer particles.

[0061] One or more sections of the absorption structure can comprise at least 99 wt% superabsorbent polymer particles.

[0062] The entire absorption structure can comprise at least 90 wt.%, preferably at least 95 wt.%, more preferably at least 98 wt.%, and even more preferably at least 99 wt.% superabsorbent polymer particles.

[0063] These embodiments are particularly preferred because absorbent articles comprising a high percentage of superabsorbent polymer particles typically have a thinner thickness in their dry state compared to conventional absorbent articles containing a higher proportion of conventional absorbent materials, such as Airfelt and the like, in addition to the superabsorbent polymer particles. The reduced thickness helps improve fit and comfort when the article is applied to the wearer.

[0064] One or more sections of the absorption structure require less than 440 s, less than 400 s, less than 350 s, less than 300 s, or less than 250 s to absorb 20 g / g (T20), as measured by the K(t) test procedure explained below.

[0065] The time to achieve an uptake of 20 g / g (T20) can be 50 s to 440 s or 100 s to 350 s or 150 s to 300 s, as measured by the K(t) test procedure explained below.

[0066] One or more sections of the absorption structure can have an effective permeability at 20 minutes (K20) of at least 2.9 × 10 –8 cm 2 exhibited, as measured by the K(t) test procedure.

[0067] One or more sections of the absorption structure can have an effective permeability at 20 minutes (K20) of at least 2.95·10 –8 cm 2 or at least 3·10 –8 cm 2 or 2.95 x 10 –8 cm 2 up to 1.0·10 –6 cm 2 , or 2.95 x 10 –8 cm 2 up to 1.0·10 –7 cm 2 , or 3.0 x 10 –8 up to 1.0·10 –7 cm 2 exhibit, as measured by the K(t) test procedure explained below.

[0068] One or more sections of the absorption structure can exhibit a ratio between the minimum effective permeability and the permeability at 20 minutes (Kmin / K20 ratio) of more than 0.75, more than 0.8, or more than 0.9, as measured by the K(t) test procedure described below. In such embodiments, the temporary gel blockage is minimal, and the liquid precipitates can migrate quickly enough through the voids present in the particles throughout the swelling process, and particularly at the beginning of the swelling phase, which is most critical for the initial surge.

[0069] The uptake by one or more sections of the absorption structure at 20 min (U20) is at least 24 g / g or at least 24.5 g / g, or 24 g / g to 60 g / g, or 24.5 g / g to 50 g / g or 24.5 g / g to 40 g / g, as measured by the K(t) test procedure described below.

[0070] In some embodiments, the entire absorption structure meets the T20, K20 and U20 values ​​mentioned above.

[0071] Absorbent materials featuring such an absorption structure exhibit improved absorption properties and therefore reduced leakage compared to prior art absorption materials, particularly during the initial surge. Such absorption structures are especially well-suited for use in absorption materials. The absorption nucleus

[0072] In some embodiments, the absorption core comprises an average amount of superabsorbent polymer particles per area of ​​50 to 2200 g / m². 2 or 100 to 1500 g / m² 2 or 200 to 1000 g / m² 2 .

[0073] In some embodiments, the absorption core comprises an average amount of superabsorbent polymer particles per area of ​​100 to 1500 g / m². 2or 150 to 1000 g / m² 2 or 200 to 900 g / m² 2 or 400 to 700 g / m² 2 in the crotch area of ​​the garment. The absorbent garment contains a sufficient quantity of superabsorbent polymer particles to provide good absorption properties while remaining thin enough to offer fit and comfort for the wearer. However, the superabsorbent polymer particles are also present in the front and back sections, although their quantity, particularly in the back section, may be low (or even zero). In some embodiments, the superabsorbent core contains an average amount of superabsorbent polymer particles per unit area of ​​less than 300 g / m². 2 or less than 200 g / m² 2 , alternatively from 25 to 300 g / m² 2 or 50 to 200 g / m² 2 or 50 to 100 g / m² 2 in the latter part of the article.

[0074] In some embodiments, the absorption core may also contain smaller amounts of absorption material other than superabsorbent polymer particles, e.g., Airfelt.

[0075] In some embodiments, the absorption core typically contains less than 5% airfelt by weight, preferably less than 2%, and more preferably it is free of airfelt. In some embodiments, the absorption structure can also be free of airfelt.

[0076] The absorption core has a dry thickness at the instep of the garment of less than 10 mm, preferably less than 5 mm, more preferably less than 3 mm, and even more preferably less than 1.5 mm, alternatively from 0.1 to 10 mm, preferably from 0.2 to 5 mm, more preferably from 0.3 to 3 mm, and even more preferably from 0.5 to 1.5 mm, as measured by the test procedure described below. The absorption core is thus sufficiently thin compared to conventional absorption cores containing Airfelt. Therefore, fit and comfort are significantly improved. The superabsorbent polymer particles

[0077] The superabsorbent polymer particles suitable for the present invention can have numerous shapes. The term "particles" refers to granules, fibers, flakes, spheres, powders, platelets, and other shapes and forms known to those skilled in the art in the field of superabsorbent polymer particles. In some embodiments, the superabsorbent polymer particles can have the form of fibers, i.e., elongated, needle-shaped superabsorbent polymer particles. In these embodiments, the fibers of the superabsorbent polymer particles have a smaller dimension (i.e., a fiber diameter) of less than about 1 mm, typically less than about 500 μm, and preferably less than 250 μm down to 50 μm. The length of the fibers is preferably about 3 mm to about 100 mm. The fibers can also have the form of a long continuous fiber, which may be woven.

[0078] Alternatively, in some preferred embodiments, the superabsorbent polymer particles of the present invention are spherical particles. According to the present invention, and in contrast to fibers, “spherical particles” have a longest and a smallest dimension with a particle ratio of the longest to the smallest particle dimension in the range of 1–5, where a value of 1 would correspond to a perfectly spherical particle and 5 would allow a certain deviation from such a spherical particle. In such embodiments, the superabsorbent polymer particles can have a particle size of less than 850 μm, or from 50 to 850 μm, preferably from 100 to 500 μm, more preferably from 150 to 300 μm, as measured by the EDANA method WSP 220.2-05.Superabsorbent polymer particles with a relatively small particle size help to increase the surface area of ​​the absorption material that comes into contact with liquid precipitates and therefore support rapid absorption of the liquid precipitates.

[0079] Superabsorbent polymer particles suitable for the present invention include various water-insoluble but water-swellable polymers capable of absorbing large quantities of fluid. Such polymer materials are generally known in the art.

[0080] Suitable superabsorbent polymer particles can be obtained, for example, from reversed-phase suspension polymerizations as described in US Patent Nos. 4,340,706 and 5,849,816, or from spray or other gas-phase dispersion polymerizations as described in US Patent Applications Nos. 2009 / 0192035, 2009 / 0258994, and 2010 / 0068520. In some embodiments, suitable superabsorbent polymer particles can be obtained using processes of the current state of the art, as described in more detail from page 12, line 23, to page 20, line 27 of WO 2006 / 083584.

[0081] In some embodiments, the surface of the superabsorbent polymer particles can be coated. In such embodiments, the coating makes the surface sticky, so that the superabsorbent polymer particles have difficulty rearranging themselves when they get wet (so that they cannot block cavities).

[0082] In some embodiments, the superabsorbent polymer particles can be coated with a cationic polymer. Preferred cationic polymers may include polyamine or polyimine materials that react with at least one component contained in bodily excretions, particularly urine. Preferred polyamine materials are selected from the group consisting of (1) polymers with primary amine groups (e.g., polyvinylamine, polyallylamine); (2) polymers with secondary amine groups (e.g., polyethyleneimine); and (3) polymers with tertiary amine groups (e.g., poly-N,N-dimethylalkylamine).

[0083] Practical examples of the cationic polymer include polyethyleneimine, a modified polyethyleneimine cross-linked by epihalohydrin in a region that is soluble in water; polyamine, a polyamidoamine modified by grafting of ethyleneimine; polyetheramine; polyvinylamine; polyalkylamine; polyamidopolyamine; and polyallylamine.

[0084] In preferred embodiments, a cationic polymer has a weight-average molecular weight of at least 500, more preferably 5,000, and most preferably 10,000 or more. Cationic polymers with a weight-average molecular weight of more than 500 are not limited to polymers that exhibit a single maximum value (a peak) in a molecular weight analysis by gel permeation chromatography, and polymers with a weight-average molecular weight of 500 or more can also be used if they exhibit multiple maximum values ​​(peaks).

[0085] A preferred amount of cationic polymer is in the range of about 0.05 to 20 parts by weight compared to 100 parts by weight of the superabsorbent polymer particles, more preferably about 0.3 to 10 parts by weight and most preferably about 0.5 to 5 parts by weight.

[0086] In some embodiments, the superabsorbent polymer particles can be coated with chitosan materials, such as those disclosed in US 7 537 832 B2.

[0087] In some other embodiments, the superabsorbent polymer particles may comprise absorbent mixed-bed ion-exchange polymers such as those disclosed in WO 99 / 34841 and WO 99 / 34842.

[0088] As mentioned above, absorption structures featuring superabsorbent polymer particles with high SFC and FSR values ​​do not automatically result in short uptake times for liquid precipitates, especially not during the initial surge, i.e., when the dry absorption structures come into contact with liquid. Without committing to a specific theory, it is generally assumed that dry superabsorbent polymer particles typically absorb water less readily than wetted superabsorbent polymer particles, since the diffusion capacity of water in dry superabsorbent polymer particles is lower than that in wetted superabsorbent polymer particles.

[0089] To date, the absorption properties of dry absorption structures comprising superabsorbent polymer particles have not been investigated with respect to initial uptake. Instead, the focus has been on the liquid flow conductivity (SFC) of the superabsorbent polymer particles, which is determined at equilibrium and thus at a stage far removed from the initial liquid uptake. In superabsorbent structures containing a significant amount of airfelt in addition to the superabsorbent polymer particles, a temporary storage of liquid entering the absorption core is enabled by the airfelt, which allows the superabsorbent polymer particles to absorb liquid from the surrounding airfelt with a certain delay.However, even with airfelt-free absorbent materials disclosed in the prior art, the permeability of the superabsorbent polymer particles is always measured at equilibrium, and therefore the behavior of dry superabsorbent polymer particles exposed to a liquid for the first time has not been considered. The inventors of the present invention have carefully investigated the behavior of absorbent structures comprising superabsorbent polymer particles when exposed to a liquid for the first time. They have found that certain previously unavailable absorbent structures comprising superabsorbent polymer particles and no or only small amounts of airfelt exhibit superior performance. This superior performance has resulted in improved liquid absorption, thereby reducing the risk of leakage.It has been found that superior absorption structures comprising superabsorbent polymer particles can be described by the time it takes for these dry absorption structures to achieve a specific liquid uptake when absorbing against an upward pressure. Therefore, it is now possible to select these newly developed absorption structures purposefully and easily, without the need for additional detailed investigations and tests.

[0090] In some embodiments, the absorption structure comprises superabsorbent polymer particles with an equilibrium permeability expressed as UPM (urine permeability measurement) of more than 50, preferably more than 60 or 50 to 500 or 55 to 200 or 60 to 150 UPM units, where 1 UPM unit is 1 × 10 –7 (cm 3 ·s) / g corresponds to.

[0091] The UPM value is measured according to the UPM test procedure described below. This test procedure is closely related to the prior art SFC test procedure. The UPM test procedure typically measures the flow resistance of a pre-swollen layer of superabsorbent polymer particles; that is, the flow resistance is measured at equilibrium. Therefore, such superabsorbent polymer particles with a high UPM value exhibit high permeability when a significant volume of the absorbent article has already been wetted by the liquid deposits. Absorbance structures incorporating such superabsorbent polymer particles show good absorption properties not only during the initial surge but also during subsequent surges.

[0092] In some embodiments, the absorption structure can comprise superabsorbent polymer particles with a Free Swell Rate (FSR) of more than 0.1 g / g / s or of 0.1 to 2 g / g / s or 0.3 to 1 g / g / s or 0.3 to 0.6 g / g / s or 0.4 to 0.6 g / g / s.

[0093] The free swelling rate of the superabsorbent polymer particles is measured according to the FSR test procedure described below. Absorption structures comprising superabsorbent polymer particles with high free swelling rate values ​​are able to rapidly absorb liquid without external pressure. In contrast to the K(t) test procedure, no external pressure is applied to the gel bed to measure the free swelling rate. Absorption structures comprising superabsorbent polymer particles with an insufficient FSR value may require at least 440 s to achieve an uptake of 20 g / g, as measured by the K(t) test procedure of the present invention, and consequently are unable to absorb the liquid excretions as quickly as necessary.As stated above, absorption structures that feature superabsorbent polymer particles with a high FSR value do not automatically lead to high uptake values ​​as measured by the K(t) test procedure.

[0094] In some embodiments, the absorption structure may include superabsorbent polymer particles with a CRC (centrifuge retention capacity) value of more than 20 g / g or more than 24 g / g or of 20 to 50 g / g or 20 to 40 g / g or 24 to 30 g / g, as measured by EDANA method WSP 241.2-05. CRC measures the liquid absorbed by the superabsorbent polymer particles for free swelling in excess liquid.

[0095] Absorption structures that include superabsorbent polymer particles with a high CRC value are preferred because fewer superabsorbent polymer particles are needed to achieve the required total liquid absorption capacity.

[0096] In some embodiments, the absorbent article may have an initial surge absorption time of less than 30 s, preferably less than 27 s, as measured by the flat absorption test procedure described below. This absorption time is measured on a baby diaper designed for wearers weighing between 8 and 13 kg ± 20% (for example, Pampers Active Fit size 4 or other Pampers size 4 baby diapers, Huggies size 4 baby diapers, or size 4 baby diapers of most other brands).An absorption article comprising an absorption structure containing superabsorbent polymer particles and requiring less than 440 s to achieve an uptake of 20 g / g, as measured by the K(t) test method, can enable shorter uptake times, particularly during the initial surge, and thus reduced leakage compared to prior art absorption articles, as illustrated in the example section of the application. Structure of the absorption nucleus

[0097] An example of an absorption core of the present invention is given below. However, the present invention is not limited to such absorption cores.

[0098] In some embodiments, the absorption core comprises 14 an absorption layer 60 , as in Fig. 3 and Fig. 4 shown. The carrier material layer 64 the absorption layer 60can be described as a dust layer and has a first surface 78 , which targets the lower class 20 the diaper 10 is directed, and a second surface 80 on, which are based on the superabsorbent polymer particles 66 is directed. According to some embodiments, the carrier material layer is 64 A nonwoven material, for example, a multilayer nonwoven material with spunbond layers as outer layers and one or more meltblown layers between the spunbond layers, including, among others, SMS material comprising a spunbond layer, a meltblown layer, and another spunbond layer. The absorption layer 60 can a covering layer 70 exhibit, as in Fig. 4 shown. The cover layer 70It can be a nonwoven material, for example a multilayer nonwoven material with spunbond layers as outer layers and one or more meltblown layers between the spunbond layers, including, among others, SMS material comprising a spunbond layer, a meltblown layer, and another spunbond layer. In some embodiments, the carrier material layer consists of 64 and the cover layer 70 made of the same material.

[0099] As in Fig. 3 and Fig. As shown in section 4, the superabsorbent polymer particles can 66 in piles of particles 66 , the sublime areas 94 and connection areas 96 between the sublime areas 94 include, on the carrier material layer 64 to be applied. As defined herein, raised areas are 94Areas where the thermoplastic adhesive material does not directly contact the nonwoven substrate or the auxiliary adhesive; as defined herein, bonding areas are 96 Areas where the thermoplastic adhesive material contacts the nonwoven substrate or the auxiliary adhesive. The bonding areas 96 contain few or no superabsorbent polymer particles 66 The sublime areas 94 and connection areas 96 They can have various shapes, including circular, oval, rectangular, triangular, and the like.

[0100] Therefore, the thermoplastic adhesive material offers 68 cavities around the superabsorbent polymer particles 66 to hold it in place and thereby immobilize this material. In another aspect, the thermoplastic adhesive bonds 68 to the carrier material layer 64 and thus fixes the superabsorbent polymer particles 66on the carrier material layer 64 In some other embodiments, the thermoplastic adhesive material penetrates 68 moreover, at least partially in both the superabsorbent polymer particles 66 as well as the carrier material layer 64 one and thus ensures further immobilization and fixation.

[0101] In some other embodiments, the absorption core can 14 have two absorption layers, a first absorption layer 60 and a second absorption layer 62 How best to Fig. 5A and Fig. 5B, which can be seen, comprises the first absorption layer. 60 of the absorption nucleus 14 a carrier material layer 64 , superabsorbent polymer particles 66 on the carrier material layer 64 and a thermoplastic adhesive material 68 on the superabsorbent polymer particles 66Although not shown, the first absorption layer can 60 also have a covering layer, such as the covering layer 70 , which in Fig. 4 is shown.

[0102] How best to Fig. 5A and Fig. 5B can be seen, the second absorption layer 62 the absorption core also includes a carrier material layer 72 , superabsorbent polymer particles 74 on the second carrier material layer 72 and a thermoplastic adhesive material 76 on the superabsorbent polymer particles 74 exhibiting this. Although not shown, the second absorption layer may 62 also have a covering layer, such as the covering layer 70 , which in Fig. 4 is shown. As indicated above, the carrier material layer can 64 the first absorption layer 60 It is referred to as a dust layer and has a first surface78 , those of the lower class 20 the diaper 10 is facing, and a second surface 80 on, which the superabsorbent polymer particles 66 is facing the 72 the second absorption layer 62 can be referred to as the core layer and has a first surface 82 , the upper layer of the diaper 10 is facing, and a second surface 84 on, which the superabsorbent polymer particles 74 is facing the first and second layers of the carrier material. 64 and 72 They can be glued together around the edge with adhesive to form a shell around the superabsorbent polymer particles. 66 and 74 to form around the superabsorbent polymer particles 66 and 74 in the absorption nucleus 14 to record.

[0103] The area of ​​the absorption nucleus14 , which has superabsorbent polymer particles, can be used depending on the desired application of the absorption core 14 and the special absorption article 10 The dimensions into which it can be incorporated vary. In some embodiments, however, the area with the superabsorbent polymer particles extends essentially over the entire absorption core. 14 In some alternative embodiments, the area with the superabsorbent polymer particles extends entirely over the absorption core. 14 in the step section 34 of the absorption article 10 , while the area with the superabsorbent polymer particles in the front and rear sections of the absorption article 10 does not extend quite over the entire absorption core.

[0104] The first and second absorption layers 60 and 62can be combined to form the absorption core 14 to form, so that the layers can be offset in such a way that the superabsorbent polymer particles 66 on the carrier material layer 64 and the superabsorbent polymer particles 74 on the carrier material layer 72 are essentially continuously distributed over the surface containing the superabsorbent polymer particles, as shown in Fig. 5A and Fig. 5B is shown. In some embodiments, superabsorbent polymer particles are used. 66 and 74 essentially evenly distributed over the surface with the superabsorbent polymer particles, although the superabsorbent polymer particles 66 and 74 over the first and second carrier material layers 64 and 72 in heaps 90are distributed discontinuously. In some embodiments, the absorption layers can be offset in such a way that the raised areas 94 the first absorption layer 60 to the connection areas 96 the second absorption layer 62 are directed, and the raised areas of the second absorption layer 62 to the connection areas 96 the first absorption layer 60 are directed, as in Fig. 5A and Fig. 5B is shown. If the raised areas 94 and connection areas 96 When appropriately sized and arranged, the resulting combination of superabsorbent polymer particles is 66 and 74 an essentially continuous layer of superabsorbent polymer particles over the surface containing the superabsorbent polymer particles of the absorption core 14 (i.e. the first and second carrier material layers)64 and 72 do not form multiple bags, each containing a pile 90 made from superabsorbent polymer particles 66 and 74 (between- and including), as in Fig. 5A is shown.

[0105] The amount of superabsorbent polymer particles can, but does not necessarily, vary along the length of the core, which is usually profiled in its longitudinal direction. It has been found that in most absorbent products, such as diapers, liquid release occurs primarily in the front half of the diaper. The front half of the absorbent core 14 It should therefore comprise the majority of the core's absorption capacity. Thus, according to certain embodiments, the front half of the absorption core can be 14 comprise more than approximately 60% of the superabsorbent polymer particles or more than approximately 65%, 70%, 75%, 80%, 85% or 90% of the superabsorbent polymer particles.

[0106] Typically, the thermoplastic adhesive material can function to at least partially immobilize the superabsorbent polymer particles in both dry and wet conditions. The thermoplastic adhesive material can be arranged essentially uniformly between the superabsorbent polymer particles. However, the thermoplastic adhesive material can typically be formed as a fibrous layer that is at least partially in contact with the superabsorbent polymer particles and partially in contact with the carrier material layer(s). Typically, the thermoplastic adhesive material of the present invention forms a fibrous network over the superabsorbent polymer particles. Typically, and as shown, for example, in the illustrations, 5A and 5B The superabsorbent polymer particles are shown. 66 and 74provided as a discontinuous layer, and a layer of fibrous thermoplastic adhesive material 68 and 76 is applied to the layer of superabsorbent polymer particles 66 and 74 deposited so that the thermoplastic adhesive material 68 and 76 in direct contact with the superabsorbent polymer particles 66 and 74 , but also in direct contact with the second surfaces 80 and 84 the carrier material layers 64 and 72 It is located where the carrier material layers are not separated from the superabsorbent polymer particles. 66 and 74 are covered. This gives the fibrous layer of thermoplastic adhesive a 68 and 76An essentially three-dimensional structure, which in itself is essentially a two-dimensional structure of relatively small thickness when compared to its longitudinal and lateral dimensions. In other words, the thermoplastic adhesive material is wavy. 68 and 76 between the superabsorbent polymer particles 68 and 76 and the second surfaces of the carrier material layers 64 and 72 .

[0107] The thermoplastic adhesive can provide cavities and envelop the superabsorbent polymer particles, thus immobilizing them. Furthermore, the thermoplastic adhesive bonds to the carrier layer(s), thereby fixing the superabsorbent polymer particles to the carrier layer(s). Some thermoplastic adhesives also penetrate both the superabsorbent polymer particles and the carrier layer(s), providing further immobilization and fixation. Although the thermoplastic adhesives disclosed herein provide improved wet immobilization (i.e., immobilization of the absorbent material when the article is at least partially loaded), these thermoplastic adhesives can also provide very good immobilization of the absorbent material when the absorbent core is dry.The thermoplastic adhesive material can also be called hot melt adhesive.

[0108] Without committing to a specific theory, it has been found that the thermoplastic adhesives most useful for immobilizing superabsorbent polymer particles combine good cohesive and adhesive properties. Good adhesion promotes good contact between the thermoplastic adhesive, the superabsorbent polymer particles, and the substrate layer(s). Good cohesion reduces the likelihood of the adhesive tearing, particularly in response to external forces, and especially tensile stress. When the absorbent core absorbs liquid, the superabsorbent polymer particles swell, subjecting the thermoplastic adhesive to external forces. The thermoplastic adhesive can accommodate this swelling without tearing and without exerting excessive compressive forces, which would impede the swelling of the superabsorbent polymer particles.

[0109] The thermoplastic adhesive may consist of only a single thermoplastic polymer or a mixture of thermoplastic polymers with a softening point, determined according to ASTM Method D-36-95 "Ring and Ball," in the range of 50°C to 300°C, or alternatively, the thermoplastic adhesive may be a hot melt adhesive comprising at least one thermoplastic polymer in combination with other thermoplastic diluents, such as tack-enhancing resins, plasticizers, and additives, such as antioxidants. In some embodiments, the thermoplastic polymer typically has a molecular weight (Mw) greater than 10,000 and a glass transition temperature (Tg) that is normally below room temperature or at -6°C < Tg < 16°C. In some embodiments, typical concentrations of the polymer in a hot melt are in the range of about 20 to about 40 wt.%.In some embodiments, the thermoplastic polymers can be water-insensitive. Examples of such polymers are (styrenic) block copolymers exhibiting ABA three-block structures, AB two-block structures, and radial (AB)n-block copolymer structures, wherein the A-blocks are non-elastomeric polymer blocks, usually composed of polystyrene, and the B-blocks are unsaturated conjugated dienes or (partially) hydrogenated versions thereof. The B-block is typically isoprene, butadiene, ethylene / butylene (hydrogenated butadiene), ethylene / propylene (hydrogenated isoprene), or a mixture thereof.

[0110] Other suitable thermoplastic polymers that can be used include metallocene polyolefins, which are ethylene polymers produced using single-site or metallocene catalysts. At least one comonomer can be polymerized with ethylene to produce a copolymer, terpolymer, or higher-order polymer. Amorphous polyolefins or amorphous polyalphaolefins (APAOs), which are homopolymers, copolymers, or terpolymers of C2- to C8-alpha olefins, are also suitable.

[0111] In some embodiments, the thermoplastic adhesive material is in the form of fibers. In some of these embodiments, the fibers have an average thickness of about 1 to about 50 micrometers or about 1 to about 35 micrometers and an average length of about 5 mm to about 50 mm or about 5 mm to about 30 mm. To improve the adhesion of the thermoplastic adhesive material to the carrier material layer(s) or any other layer, in particular to any other nonwoven layer, such layers can be pretreated with an auxiliary adhesive.

[0112] In certain embodiments, the thermoplastic adhesive material is used in an amount between 0.5 and 30 g / m². 2 , between 1 and 15 g / m² 2 , between 1 and 10 g / m² 2 or even between 1.5 and 5 g / m² 2 applied per carrier material layer.

[0113] An example thermoplastic adhesive material 68 and76The storage modulus G', measured at 20°C, can be at least 30,000 Pa and less than 300,000 Pa, or less than 200,000 Pa, or between 140,000 Pa and 200,000 Pa, or less than 100,000 Pa. In another aspect, the storage modulus G', measured at 35°C, can be greater than 80,000 Pa. In yet another aspect, the storage modulus G', measured at 60°C, can be less than 300,000 Pa and more than 18,000 Pa, or more than 24,000 Pa, or more than 30,000 Pa, or more than 90,000 Pa. In another aspect, the storage modulus G', measured at 90°C, can be less than 200,000 Pa and more than 10,000 Pa, or more than 20,000 Pa, or more than 30,000 Pa. The storage modulus measured at 60°C and 90°C can be a measure of the dimensional stability of the thermoplastic adhesive material at elevated ambient temperatures.This value is particularly important when the absorbent product is used in a warm climate, where the thermoplastic adhesive material would lose its integrity if the storage modulus G' at 60°C and 90°C is not sufficiently high.

[0114] G' is measured using a rheometer, as shown schematically and for general illustration only in Fig. Figure 6 is shown. The rheometer 627 It is capable of applying a shear stress to the adhesive and measuring the resulting load response (shear deformation) at a constant temperature. The adhesive is applied between a Peltier element, which serves as the lower, stationary plate. 628 serves, and a top plate 629The plates are laid with a radius R of 10 mm and then connected to the drive shaft of a motor to generate the shear stress. The gap between the two plates is 1500 micrometers high. The Peltier element allows for temperature control of the material (+0.5°C). The load amplitude is set to 0.05%, the load frequency to 1 Hz, and the cooling rate to 2°C / min (with a starting temperature of 150°C or higher and a final temperature of -5°C).

[0115] The absorption core may also include an auxiliary adhesive, which is not shown in the illustrations. The auxiliary adhesive may be applied to the carrier layer(s) prior to the application of the superabsorbent polymer particles to the carrier layer(s) to enhance the adhesion of the superabsorbent polymer particles and the thermoplastic adhesive to the respective carrier layers. The auxiliary adhesive may also contribute to the immobilization of the superabsorbent polymer particles and may comprise the same thermoplastic adhesive as described above or may comprise other adhesives, including sprayable hot melt adhesives. An example of a commercially available auxiliary adhesive is HB Fuller Co. (St. Paul, MN) product no. HL-1620-B.The auxiliary adhesive can be applied to the carrier material layer(s) in any suitable manner, but according to some embodiments it can be applied in gaps approximately 0.5 to approximately 1 mm wide, spaced approximately 0.5 to approximately 2 mm apart. The upper class

[0116] The absorption article 10 can an upper class 18 include, which may be permeable to liquids. The upper layer 18It can be manufactured from a wide range of materials, for example, woven and nonwoven fabrics; polymeric materials such as perforated thermoplastic films, perforated plastic films, and hydroformed thermoplastic films; porous foams; mesh foams; mesh thermoplastic films; and thermoplastic grids. Suitable woven and nonwoven materials can be natural fibers (e.g., wood or cotton fibers), synthetic fibers (e.g., polymeric fibers such as polyester, polypropylene, or polyethylene fibers), or a combination of natural and synthetic fibers.

[0117] In some embodiments, the upper layer 18 consist of a hydrophobic material to insulate the wearer's skin from liquids that penetrate the upper layer 18have penetrated. In such embodiments, at least a part of the upper surface of the top layer is 18 It is treated to become hydrophilic, allowing fluids to pass through the surface layer more quickly. This reduces the likelihood of bodily fluids being absorbed through the surface layer. 18 drain away instead of into the upper layer 18 to be drawn in and absorbed by the absorption nucleus. The upper layer 18 It can be made hydrophilic by treatment with a surfactant. Suitable methods for treating the surface layer. 18 with a surfactant involves spraying the top layer material with the surfactant and immersing the material in the surfactant.

[0118] In some embodiments, the top layer features a perforated film. Perforated films are permeable to bodily excretions but non-absorbent and have a reduced tendency to allow fluid to re-wett the wearer's skin. Thus, the surface of the molded film that comes into contact with the body remains dry, reducing soiling and providing a more comfortable feel for the wearer. Suitable molded structures are described in U.S. Patent No. 3,929,135 entitled "Absorptive Structures Having Tapered Capillaries," granted to Thompson on December 30, 1975; and in U.S. Patent No. 4,324,246 entitled "Disposable Absorbent Article Having A Stain Resistant Topsheet," granted to Mullane et al. on April 13, 1982. in US patent no. 4,342,314 entitled “Resilient Plastic Web Exhibiting Fiber-Like Properties”, granted to Radel et al. on 3.August 1982; described in US Patent No. 4,463,045 entitled “Macroscopically Expanded Three-Dimensional Plastic Web Exhibiting Non-Glossy Visible Surface and Cloth-Like Tactile Impression”, granted to Ahr et al. on July 31, 1984; and in US Patent No. 5,006,394 “Multilayer Polymeric Film”, granted to Baird on April 9, 1991.

[0119] Alternatively, the top layer may consist of perforated nonwoven materials. Suitable perforated nonwoven materials are described in US Patent No. 5,342,338 and PCT Application No. WO 93 / 19715. The lower class

[0120] The absorbent article can form a sublayer 20The bottom layer may be attached to the top layer. It can prevent excrement absorbed by the absorbent core and retained in the diaper from soiling other external items that may come into contact with the diaper, such as sheets and underwear. In some embodiments, the bottom layer may be substantially impermeable to liquids (e.g., urine) and may comprise a laminate of nonwoven fabric and a thin plastic film, for example, a thermoplastic film with a thickness of about 0.012 mm (0.5 mil) to about 0.051 mm (2.0 mils). Suitable bottom layer films include those manufactured by Tredegar Industries Inc., Terre Haute, India, and sold under the brand names X15306, X10962, and X10964.Other suitable underlayer materials may include breathable materials that allow vapors to escape from the diaper while preventing liquid excrement from passing through the underlayer. Examples of breathable materials may include woven sheets, nonwoven sheets, composite materials such as film-coated nonwoven sheets, and microporous films such as those manufactured by Mitsui Toatsu Co., Japan, under the name ESPOIR NO, and by EXXON Chemical Co., Bay City, Tex., under the name EXXAIRE. Suitable breathable composite materials comprising polymer blends are available from Clopay Corporation, Cincinnati, Ohio, under the name HYTREL Blend P18-3097. Such breathable composite materials are described in more detail in PCT Application No. WO 95 / 16746, filed on June 22, 1995, on behalf of E.L. DuPont.Other breathable underlayers, comprising nonwoven fabrics and perforated film, are described in US Patent No. 5,571,096, granted to Dobrin et al. on November 5, 1996. Test procedure • K(t) test procedure (test procedure for measuring dynamic effective permeability and uptake kinetics)

[0121] This method determines the time-dependent effective permeability (K(t)) and uptake kinetics of an absorption structure containing superabsorbent polymer particles under top pressure. The aim of this method is to determine the ability of the absorption structure containing the superabsorbent polymer particles to absorb and distribute body fluids when the polymer is present in high concentrations within an absorbent article and is subjected to mechanical pressures such as those typically encountered during use of the absorbent article. Darcy's law and equilibrium flow methods are applied to calculate the effective permeability (see below). (See also, for example, "Absorbency," ed. P.K. Chatterjee, Elsevier, 1982, pages 42–43, and "Chemical Engineering Vol. II, Third Edition," J.M. Coulson and J.F. Richardson, Pergamon Press, 1978, pages 122–127.)

[0122] In contrast to previously published methods, the sample is not pre-swelled; therefore, the hydrogel is not formed by pre-swelling hydrogel-forming superabsorbent polymer particles in synthetic urine, but the measurement begins with a dry structure.

[0123] The equipment used for this procedure is called a 'time-dependent permeability test rig' or 'Time Dependent Permeability Tester', device no. 03-080578, and is available from BRAUN GmbH, Frankfurter Str. 145, 61476 Kronberg, Germany, and is described below. Operating instructions, wiring diagrams, and detailed technical drawings are also available upon request. Measurement system for dynamic effective permeability and uptake kinetics

[0124] Fig.Figure 7 shows the measurement system for dynamic effective permeability and uptake kinetics, which is referred to herein as the 'time-dependent permeability test rig'.

[0125] The equipment consists of the following main components: – digital laser sensor M11 for thickness measurements, 701 (MEL Mikroelektronik GmbH, 85386 Eching, Germany) – Fiber for liquid level sensing, 702 (FU95, Keyence Corp., Japan) – digital fiber sensor 703 (FS-N10, Keyence Corp., Japan) – Precision scale 704 (XP6002MDR, Mettler Toledo AG, 8606 Greifensee, Switzerland) – Logo!Power power unit (C98130-A7560-A1-5-7519, Siemens AG) – LabVIEW software license 706 (National Instruments, Austin, Texas, USA) – Collection container 707 (5 l glass flask, Roth) – Storage container 708 (5 l glass bottle, VWR) with spout 709and open-ended pipe for air supply 723 – Control unit and console 705 (Conrad Electronics) – computer-aided data acquisition system 710 – a piston / cylinder arrangement 713 as described herein – a controlled valve 714 (Bürkert)

[0126] Fig. Figure 8 shows the piston / cylinder arrangement. 713 , which has a piston guide cover 801 , a piston 802 and a cylinder 803 exhibits. The cylinder 803 consists of transparent polycarbonate (e.g. Lexan) ® ) and has an inner diameter p of 6.00 cm (area = 28.27 cm²). 2 ). The inner cylinder walls 850 They are smooth; the height of the cylinder r is approximately 7.50 cm. The base 804 of the cylinder 803 is equipped with a stainless steel filter cloth, US standard 400Mesh, (not shown) claimed (by Weisse and Eschrich), which is biaxially stretched taut before being placed on the ground 804 of the cylinder 803 is attached. The piston 802 consists of a stainless steel piston body 805 and a stainless steel headpiece 806 The diameter q of the piston head piece 806 is slightly smaller than 6 cm, so that it fits freely in the cylinder 803 can slide without leaving a gap through which the hydrogel-forming particle can pass. The piston body 805 is vertical in the middle of the piston head piece 806 The piston head has a diameter of approximately 2.2 cm. The piston body... 805 is then inserted into a piston guide cover 801 introduced. The guide cover 801 has a POM (polyoxymethylene) ring 809 with a diameter that allows the piston to slide freely 802 allows, but the piston body 805exactly vertical and parallel to the cylinder walls 850 stops as soon as the piston 802 with the guide cover 801 on top of the cylinder 803 has been arranged. The top view of the piston head piece 806 is in Fig. 9 shown. The piston head piece 806 should distribute the pressure evenly across the sample 718 It is also highly permeable to hydrophilic fluids, so it does not restrict the fluid flow during measurement. The piston head piece 806 features a stainless steel mesh cloth 903 , US standard 400 Mesh (e.g. from Weisse and Eschrich), which is biaxially stretched tightly and attached to the stainless steel outer ring 801 The piston head is secured. The entire bottom surface of the piston is smooth. The structural integrity and bending resistance of the mesh are then ensured by the radial stainless steel spokes. 902 Ensured. The height of the piston head piece. 805is selected so that the weight of the piston 802 , which is from the piston body 805 and the piston head piece 806 consists of 596 g (± 6 g), which corresponds to 2.07 kPa (0.30 psi) over the surface of the cylinder. 803 .

[0127] The piston guide cover 801 is a flat circle made of stainless steel with a diameter of approximately 7.5 cm, which is surrounded by the POM ring 809 in its center perpendicular to the piston body 805 is held. There are two inlets in the guide cover ( 810 and 812 ).

[0128] The first entrance 812 enables positioning of the fiber for liquid level sensing 705 exactly 5 cm above the top of the grid (not shown), which is on the ground ( 804 ) of the cylinder 803 is attached as soon as the piston 802 for measurement with the cylinder 803 has been assembled.

[0129] The second entrance 810 allows the connection of a liquid pipe 721 , which provides the liquid for the experiment.

[0130] To ensure that the piston assembly 802 with the cylinder 803 If carried out consistently, a slot will be created. 814 on the cylinder 803 attached, which is marked with a position marker 813 in the guide cover 801 This ensures that the rotation angle of the cylinder and the guide cover are always the same.

[0131] The stainless steel mesh cloth should be cleaned before each use. 903 of the piston head piece 806 and the cylinder 803 The grid must be checked for blockages, holes, or overstretching and replaced if necessary. A K(t) device with a damaged grid can produce inaccurate K(t) and uptake kinetics results and must not be used until the grid has been replaced.

[0132] A 5 cm mark 808 is placed at a height k of 5.00 cm (± 0.02 cm) above the top of the grid, which is on the ground 804 of the cylinder 803 It is attached, mounted, or etched. This marks the fluid level to be maintained during the analysis. The fiber for liquid level measurement. 702 It will be positioned exactly at the 5 cm mark. 808 arranged. Maintaining a correct and constant fluid level (hydrostatic pressure) is critical for measurement accuracy.

[0133] A storage container 708 , which is connected via a pipe to the piston / cylinder arrangement 713 is connected and contains the sample, and a control valve 714 are used to add salt solution to the cylinder 803 to supply and to maintain the level of the salt solution at a height k of 5.00 cm above the top of the grid located at the bottom of the cylinder 804is attached. The valve 714 , the fiber for liquid level measurement 702 and the digital fiber sensor 703 are via the control unit 705 with the computer-aided recording system 710 connected. This allows the system for measuring dynamic effective permeability and uptake kinetics to use information from the fiber for liquid level sensing. 702 and the digital fiber sensor 703 use to open the valve 714 to control and finally the liquid level at the 5 cm mark 808 to keep.

[0134] The storage container 708 In this way, above the piston / cylinder arrangement 713 It is arranged that a hydrohead column of 5 cm is formed within 15 seconds of the start of the test and maintained in the cylinder throughout the entire test procedure. The piston / cylinder arrangement 713is mounted on the carrier ring 717 the cover plate 716 arranged, and the first admission 812 will be connected to the docking carrier 719 This leaves only one position for the guide cover. 801 Furthermore, due to the position marker... 813 even just one position of the cylinder 803 The grid that is at the bottom of the cylinder 804 The mounting surface must be perfectly flat and horizontal. The support ring 717 must have an inner diameter small enough to fit the cylinder 803 to support firmly, but be larger than 6.0 cm so that it lies outside the inner diameter of the cylinder once the cylinder is on the support ring 717 This has been arranged. This is important to prevent any disruption of the fluid flow through the support ring. 717 to avoid.

[0135] The salt solution, which is applied to the sample with a constant 5 cm hydrohead column, can now flow freely from the flask / cylinder arrangement. 713 into a collecting container 707 flowing, which is on the scales 704 It is arranged to measure accurately within ± 0.01 g. The digital output of the scale is connected to a computer-aided data acquisition system.

[0136] The thickness of the sample is constantly measured using a digital laser sensor for thickness measurement. 701 , measured. The laser beam 720 of the digital laser sensor 701 is placed on the center of the POM cover plate 811 directed at the piston body. Through the precise positioning of all parts of the piston / cylinder assembly. 713 is the piston body 805 completely parallel to the laser beam 720 , and consequently an exact measurement of the thickness is obtained. Test preparation

[0137] The storage container 708 The container is filled with test solution. The test solution is an aqueous solution containing 9.00 grams of sodium chloride and 1.00 gram of surfactant per liter of solution. The preparation of the test solution is described below. The collecting vessel 707 will be placed on the scales 704 posed, which are equipped with a computer-aided data acquisition system 710 It is connected. Before the measurement starts, the scale is reset to zero. Preparation of the test liquid:

[0138] Required chemicals: – Sodium chloride (CAS#7647-14-5, e.g.: Merck, cat no. 1.06404.1000) – linear C 12 -C 14 -Alcohol ethoxylate (CAS#68439-50-9, e.g. Lorodac ® , Sasol, Italy) – deionized H2O

[0139] Ten liters of a solution containing 9.00 grams of NaCl per liter and 1.00 gram of linear C12-C14 alcohol ethoxylate per liter in distilled water are kept at 23°C ± 1°C for 1 hour. The surface tension is measured on three individual aliquots and should be 28 ± 0.5 mN / m. If the surface tension deviates from 28 ± 0.5 mN / m, the solution is discarded and a new test solution is prepared. The test solution must be used within 36 hours of its preparation; after this time, it is considered expired. K(t) sample preparation

[0140] A typical circular section of the absorbing structure with a diameter of 6.00 cm is obtained. This section of the absorbing material can be obtained using a suitable circular die and a hydraulic pressure cutter (e.g., Electro-Hydraulic Alfa Cutter 240-10, available from Thwing-Albert Instrument Company, 14 W. Collings Ave., West Berlin, NJ 08091).

[0141] The circular sample 118 is carefully laid flat on the (not shown) grid which is on the floor 204 of the cylinder 203 It is attached so that it occupies all the available space on the grid. It is important to ensure the circular sample is secure. 118The sample should be arranged so that the side in direct contact with the grid is the one normally furthest from the liquid source, in order to reproduce the flow direction typically encountered in use. For example, for samples involving absorbent items such as diapers, the side usually facing the wearer should be placed at the top, while the side facing the clothing should be in contact with the grid at the bottom of the cylinder. Careful sample arrangement is critical for measurement accuracy. If the absorbing structure is small and a 6.0 cm diameter sample cannot be obtained from it, two absorbing structures of the same size can be joined together to obtain the necessary minimum sample size. The two samples must be taken from the same location on the two identical absorbing structures.The two absorption structures should be joined at a straight edge and trimmed if necessary to achieve this straight edge. The goal is for the joined edges to form a flat, homogeneous layer with little or no gap. This joined layer is then subjected to the standard sample preparation procedure described above, with the additional precaution of centering the joint line in the die to obtain two semicircles of identical shape. It is important that both semicircles are carefully positioned within the sample holder to form a complete circle and cover the entire available surface area on the grid with little or no gap. Both halves must be positioned so that their sides face the grid, as described above.However, in most embodiments, the sample consists of a uniform circular section of the absorption structure. Method for extracting an absorption structure from an absorption article

[0142] The absorbent material is placed on a flat surface. If the product has features that prevent it from being laid flat (for example, elastic cuffs), these are cut at appropriate intervals so that the product can be laid flat.

[0143] First, one or more sections of the absorption structure containing at least 90 wt% superabsorbent polymer particles, which are to be tested using the K(t) test method, are identified and should be isolated as described below.

[0144] All materials that are not part of the absorption structure are removed from the absorption structure, taking care not to damage the absorption structure unnecessarily.

[0145] If the materials to be removed are attached to the absorption structure, for example by adhesive material such as thermoplastic adhesive, they could be removed using cold sprays with a cooling temperature of -50 to -60°C (for example, “IT Icer” or “PRF 101 Cold Spray”, available from Taerosol, Kangasala, Finland) to avoid damage to the structure, as in, for example, Fig. 15 is shown.

[0146] Fig. Figure 15 shows an absorption structure 151 , the superabsorbent polymer particles 152 includes the area between two carrier material layers 153 , 154 are arranged. A layer of material 156 is attached to one of the carrier material layers 153 ,154 It is attached and therefore not part of the absorption structure. 151 This layer must be separated from the absorption structure. 151 be removed. To avoid unnecessary damage to the absorption structure. 151 To avoid this, the material layer will be 156 , which are derived from the absorption structure 151 to be removed in a 180° extraction geometry from the absorption structure 151 peeled off while the adhesive material 155 with the cold spray 157 It is cooled. Spraying should be done for each individual section of the material layer. 156 last at least 1 second, but no longer than 5 seconds.

[0147] After removing the respective material, the remaining part of the absorption structure is held under a pressure of 2.07 kPa (0.3 psi) until the temperature returns to its initial value (TAPPI laboratory condition).

[0148] The upper layer and / or the lower layer of the absorption structure can be appropriately perforated to allow a fluid flow to pass through, as in, for example, Fig. Figure 16 shows an absorption structure 161 The superabsorbent polymer particles are shown. 162 includes the area between two carrier material layers 163 , 164 are arranged. The perforation is carried out using a hot metal tip, also known as a perforation tip. 165 is referred to and which contains a steel rod 166 comprising a diameter H of 0.7 ± 0.2 mm. A standard paper clip around a soldering tip. 167 For example, the CT 60 / 621, available from ERSA GmbH, Wertheim, Germany, which is curved, can be used for this purpose. The perforation tip 165 It should be set to a temperature of 310 ± 20°C. The perforation tip 165It is placed in contact with the layers to be perforated for a short period of time at low pressure in order to perforate the layers, for example by melting, without affecting any of the other materials of the absorption structure. 161 to impair. The holes are produced in the same way in a regular perforation pattern with a hole spacing from edge to edge, D, of 1 ± 0.2 mm, as for example in Fig. 17 is shown.

[0149] Each absorption structure is visually inspected for integrity using backlighting and discarded if damaged. Examples of damage include cuts, holes, and creases that were not present before the absorption structure was removed from the absorption article. Perforations in the layers created with the perforation tip are not considered damage if they do not affect other layers. Significant migration of superabsorbent polymer particles and fibers within the absorption structure is also considered damage.

[0150] The absorption structures that have been prepared in this way are then cut according to the K(t) test procedure. K(t) approach

[0151] The measurement is performed under Tappi laboratory conditions: 23°C ± 1°C / 50% RH ± 2%.

[0152] The empty piston / cylinder arrangement 713is placed in the circular opening of the cover plate 716 It is attached and supported by the carrier ring around its lower edge. The piston / cylinder arrangement 713 will be connected to the docking carrier 719 held while the cylinder 803 and the piston 802 must be aligned at the correct angle. The reference thickness measurement (r) r The value is measured by the digital laser sensor. Then the empty piston / cylinder assembly is... 713 from the cover plate 716 and the carrier ring 717 taken, and the piston 802 is from the cylinder 803 removed.

[0153] The sample 718 The absorption structure is arranged on the cylinder grid as described above. Then the piston... 802 , the one with the guide cover 801 Once assembled, carefully place it in the cylinder. 803 set, whereby the position marker 813 of the guide cover 801with the slot 814 is brought into agreement.

[0154] The piston / cylinder arrangement is connected to the docking carrier. 719 held in place while the cylinder and piston are aligned at the correct angle.

[0155] This can only be done in one direction. The liquid pipe 721 , the one with the storage container 708 is connected, and the digital fiber sensor 703 are accessed via the two entrances 810 and 812 in the guide cover 801 introduced into the piston / cylinder assembly.

[0156] The computer-aided data acquisition system 710 is used for thickness measurement 701 with the scale 704 and connected to the digital laser sensor. A fluid flow from the reservoir. 708 to the cylinder 803 is initiated by the computer program through the opening of the valve. 714The process is initiated. The cylinder is filled until the 5 cm mark is reached in 5 to 15 seconds, after which the computer program regulates the flow rate to maintain a constant hydrohead column of 5 cm. The amount of solution passing through the sample 718 Passing through, it is weighed by the scales. 704 The thickness increase is measured by the laser thickness gauge. Data acquisition starts when the fluid flow is initiated, more precisely when the valve... 714 The measurement process begins when the device is first opened and continues for 21 minutes, or until the reservoir is empty and the 5 cm high hydrohead column can no longer be maintained. The measurement duration is 21 minutes, with laser thickness and balance readings recorded regularly at intervals that can vary from 2 to 10 seconds depending on the measurement range, and three replicates are taken.

[0157] After 21 minutes, the measurement of the first replication is successfully completed, and the controlled valve... 714 It closes automatically. The piston / cylinder arrangement 713 The device is removed, and the measurements for the second and third replications are carried out accordingly, always following the same procedure. At the end of the third replication measurement, the controlled valve shuts off. 714 the liquid flow and a tap 722 of the storage container 708 The process is now closed. The collected raw data is stored in the form of a simple data table, which can then be easily imported into a program for further analysis, e.g., Excel 2003, SP3.

[0158] The data table provides the following relevant information for each measurement: • Time from the start of the experiment • Weight of the liquid collected from the container 707 on the scale 704 is caught • Sample thickness 718

[0159] The data from 30 seconds until the end of the experiment are used to calculate K(t) and the uptake kinetics. The data collected in the first 30 seconds are not included in the calculation. The effective permeability K(t) and the uptake kinetics of the absorption structure are then determined using the following sets of equations. Equations used:

[0160] The table below describes the notation used in the equations. A Cross-section of the absorption structure sample corresponding to the inner radius of the cylinder: 28.27 cm H Height of the water column: 5.0 cm Δp Driving pressure applied by the 5.00 cm high hydrohead column (h): 4929.31 g / (cm s) 2 ) G Gravitational constant: 981 cm / s 2 η temperature-dependent effective viscosity of the liquid in g / (cms) T Temperature in °C ρ Density of the liquid: 1.0053 g / cm³ 3 r s A Bulk density of the sample of porous medium or powder g / cm³ 3 r s Average density of the solid part of the dry sample in g / cm³ 3 r s k Density of component k of the dry sample in g / cm³ 3 M Dry mass of the sample in g: 2.00 g when measuring superabsorbent particles m k Mass of component k of the dry sample in g V s Volume of the dry sample in cm³ 3 t i Time at step i of N discrete points in s d i Thickness of the absorption structure sample at time t i in cm r i Measurement result of the thickness measuring instrument at time t i in cm r r Reference measurement of the thickness gauge (measurement of the piston / cylinder arrangement without sample) in cm m aus i Scale reading at time t i ; mass of the liquid present at time t i has left the sample, in g U(t i ) Sample collection at time t i in g T20 Time required to reach an intake of 20 g / g, starting from 0 s (t0), in s U20 Sample taken after 20 minutes in g / g T80% Time required to achieve 80% uptake of U20, starting at 0 s (t0), in s K20 Sample permeability at 20 minutes in m 2 Kmin minimum permeability value during the experiment in m 2 Kmin / K20 ratio of Kmin and K20

[0161] The driving pressure is calculated from the hydrohead column as follows: Δp = h G ρ = 4929.31 g / (cm s 2 )

[0162] The thickness at the respective time t i is calculated as the difference between the measured value of the thickness sensor at time t i and the reference measurement value calculated without a sample: d i = r i– r r [cm]

[0163] For samples made of superabsorbent particles, the thickness of the sample at time t is determined. i = 0 (d0) is used to evaluate the quality of the particle scattering.

[0164] The bulk density inside the cylinder can indeed be calculated as follows:

[0165] If the bulk density in the cylinder differs from the bulk density of the powder by more than ± 40%, the measurement must be considered invalid and eliminated.

[0166] The bulk density can be measured using the EDANA method 406.2-02 (“superabsorbent materials – superabsorbent polyacrylate powder – GRAVIMETRIC DENSITY DETERMINATION”).

[0167] The time-dependent rate of change of the scale measurement result at time t i is calculated as follows:

[0168] The time-dependent rate of change of the thickness measurement result at time t i is calculated as follows:

[0169] The uptake kinetics are calculated as follows:

[0170] With dry sample volume (V s ) refers to the framework volume of the sample, therefore V s the actual volume occupied by the solid material in the dry sample, excluding pores and any interstices.

[0171] V s can be calculated or measured using various methods known to a person skilled in the art; for example, if the exact composition and the matrix density of the components are known, it can be determined as follows:

[0172] For an unknown material composition, V s Alternatively, they can be calculated as follows:

[0173] The average density ρs The K(t) value can be calculated by pycnometry using a suitable non-swelling liquid of known density. This technique cannot be applied to the same samples subsequently used for the K(t) measurements; therefore, a suitable additional set of samples should be prepared as examples for this experimental measurement.

[0174] From U(t) at the various time steps, calculated as described above, the uptake at any given time can be determined by linear extrapolation. For example, one of the most important results is the uptake at 20 minutes, also known as U20 (in g / g).

[0175] From the U(t) values ​​at different time steps, the time required to reach a specific intake level can be determined by interpolation. The time until an intake level of 20 g / g is first reached is denoted as T20. Similarly, the time until other intake levels are reached can be calculated accordingly (e.g., T5 or T10). If U20 is known, the time until 80% of U20 is reached can also be determined from the U(t) values ​​at different time steps; this property is denoted as T80%.

[0176] The effective permeability is calculated from the mass change and thickness change rates as follows:

[0177] The effective viscosity of the liquid depends on the temperature and is calculated within the interval of the experiment (23°C ± 1°C) according to the following equation: η = A + B·T [g / (cm·s)] where A = 1·479·10 –2 [g / (cm·s)] and B = –2.36·10 –4 [g / (cm·s·°C)]

[0178] The effective permeability at a specific time can be determined from K(t) by linear interpolation. For example, one of the most important results is the measurement at 20 minutes or K20 (m 2 Similarly, the permeability can be calculated at any other time (e.g., K5 or K10).

[0179] Another parameter that can be derived from the data is Kmin, which is the minimum K(t) value over the entire curve of the interval t. i = 30 s to t iThe permeability is measured at 1200 s. This value is useful for calculating Kmin / K20, which is the ratio between the minimum effective permeability and the permeability at 20 minutes. This parameter reflects the temporary gel blockage that might occur in some samples. A value close to 1 indicates no temporary gel blockage, while a value close to 0 suggests that the material initially experiences a sharp drop in effective permeability when loaded with liquid.

[0180] The average values ​​for T20, T80%, K20, U20 and Kmin / K20 are reported from 3 replications, according to the required accuracy known to the person skilled in the art. • Thickness measurement test procedures,

[0181] This procedure aims to establish a method for determining the thickness of the absorption core at the step point of the absorption article. The test can be performed using a conventional thickness gauge, for example, type EG-225, available from ONO SOKKI Technology Inc., 2171 Executive Drive, Suite 400, Addison, IL 60101, USA, with a suitable gauge stand having a 41 mm diameter circular aluminum base and a force of 0.1 Newton (10 gf) applied to the base. An additional weight is added to achieve a total of 1.6 Newtons (160 gf) to adjust the pressure to 1.18 kPa (0.173 psi).

[0182] The thickness of the absorption core is determined before it is inserted into the absorption article, after its exact position within the article has been determined. However, the thickness can also be determined after the absorption core has been removed from a finished product using a method known to those skilled in the art.

[0183] The step point of an absorption article is determined at the intersection of the longitudinal center line and the transverse center line. Basic Protocol 1. All tests are performed at 23 ± 1°C and 50 ± 2% relative humidity. 2. The absorption nucleus is allowed to seek equilibrium at 23 ± 1°C and 50 ± 2% relative humidity. 3. The step point is determined as described above and marked on the support surface of the absorption core. 4. The absorption core is placed under the thickness gauge with the support surface facing the sample contact foot and with the step point centered under the foot. 5. The sample contact foot is carefully lowered until it comes into contact with the surface of the absorption core. 6. The thickness measurement is read 5 seconds after the foot makes contact with the absorption core. • Procedure for testing urine permeability measurement (UPM) Urine permeability measurement system

[0184] This method determines the permeability of a swollen hydrogel layer. 1318 The equipment used for this procedure is described below. This procedure is closely related to the state-of-the-art SFC (fluid transfer) test procedure.

[0185] Fig.Figure 10 shows a permeability measurement system 1000 , which is connected to the storage vessel with a constant hydrostatic column, 1014 , an open-ended pipe for air supply, 1012 , a laboratory lifting platform 1016 , a feed pipe 1018 , a rooster 1020 , a tripod ring 1022 , a collecting container 1024 , a scale 1026 and a piston / cylinder arrangement 1028 is equipped.

[0186] Fig. Figure 11 shows the piston / cylinder arrangement. 1028 , which is a metal weight 1112 , a piston shaft 1114 , a piston head piece 1118 , a lid 1116 and a cylinder 1120 includes The cylinder 1120 consists of transparent polycarbonate (e.g. Lexan) ® ) and has an inner diameterp of 6.00 cm (area = 28.27 cm²). 2 ) with smooth inner cylinder walls 1150 up. The ground 1148 of the cylinder 1120is covered with a stainless steel mesh fabric, US standard 400 mesh (not shown), which is biaxially stretched taut before being laid on the floor 1148 of the cylinder 1120 is attached. The piston shaft 1114 consists of transparent polycarbonate (e.g. Lexan) ® ) and has a total length q of approximately 127 mm. A mean step 1126 of the piston shaft 1114 It has a diameter r of 21.15 mm. An upper section 1128 of the piston shaft 1114 has a diameter s of 15.8 mm and forms a step 1124 A lower section 1146 of the piston shaft 1114 It has a diameter t of approximately 1.6 cm (5 / 8 inch) and is threaded so that it fits firmly into the central opening. 1218 (see Fig. 12) of the cylinder head 1118 can be screwed in. The piston head piece 1118is perforated, made of transparent polycarbonate (e.g. Lexan) ® ), and is also covered with a stretched stainless steel mesh fabric, US standard 400 mesh (not shown). The weight 1112 Made of stainless steel, features a central bore 1130 up, slides onto the upper section 1128 of the piston shaft 1114 and lies on the heel 1124 on. The combined weight of the piston head piece 1118 , of the piston shaft 1114 and the weight 1112 The pressure is 596 g (± 6 g), which is 2.07 kPa (0.30 psi) across the surface of the cylinder. 1120 This corresponds to the combined weight. It can be determined by drilling a blind hole along a central axis. 1132 of the piston shaft 1114 The cylinder cover can be modified to remove material and / or create a cavity to add weight. 1116 It has a first lid opening in its center. 1134 , to the piston shaft1114 to align vertically, and near the edge 1138 a second lid opening 1136 to draw fluid from the reservoir with a constant hydrostatic column, 1014 , into the cylinder 1120 to introduce.

[0187] A first linear index marking (not shown) is placed radially along the top surface. 1152 of the weight 1112 incised or affixed, with the first linear index mark perpendicular to the central axis 1132 of the piston shaft 1114 A corresponding second linear index marking (not shown) runs radially along the top surface. 1160 of the piston shaft 1114 attached, with the second linear index mark perpendicular to the central axis 1132 of the piston shaft 1114 a corresponding third linear index marker (not shown) runs along the middle section. 1126 of the piston shaft 1114attached, with the third linear index mark parallel to the central axis 1132 of the piston shaft 1114 A corresponding fourth linear index marking (not shown) runs radially along the top. 1140 of the cylinder head 1116 attached, with the fourth linear index mark perpendicular to the central axis 1132 of the piston shaft 1114 It runs. Furthermore, a corresponding fifth linear index marking (not shown) is placed along a nozzle. 1154 of the cylinder section 1156 attached, with the fifth linear index mark parallel to the central axis 1132 of the piston shaft 1114 a corresponding sixth linear index marking (not shown) runs along the outer cylinder wall. 1142 attached, with the sixth linear index mark parallel to the central axis 1132 of the piston shaft 1114The process unfolds. A match between the first, second, third, fourth, fifth, and sixth linear index markers allows for a repositioning of the weight. 1112 , of the piston shaft 1114 , of the cylinder head 1116 and the cylinder 1120 with the same orientation relative to each other for each individual measurement.

[0188] The specification details for the cylinder 1120 are: Outer diameter u of the cylinder 1120 : 70.35 mm Inner diameter p of the cylinder 1120 : 60.0 mm Height ν of the cylinder 1120 : 60.5 mm

[0189] The cylinder cover specification details 1116 are: Outer diameter w of the cylinder cover 1116 : 76.05 mm Inner diameter x of the cylinder cover 1116 : 70.5 mm Thickness y of the cylinder head 1116 including the nozzle 1154 : 12.7 mm Thickness z of the cylinder head 1116 without nozzle 1154: 6.35 mm Diameter a of the first lid opening 1134 : 22.25 mm Diameter b of the second lid opening 1136 : 12.7 mm Distance between the centers of the first and second lid openings 1134 and 1136 : 23.5 mm

[0190] The weight specification details 1112 are: Outer diameter c: 50.0 mm Diameter d of the middle bore 1130 : 16.0 mm Height e: 39.0 mm

[0191] The piston head specification details 1118 are: Diameter f: 59.7 mm Height g: 16.5 mm Outer holes 1214 (14 in total) with a diameter h of 9.65 mm, outer holes 1214 , which are evenly spaced, with centers 47.8 mm from the center of the central opening 1218 are spaced apart Inner holes 1216 (a total of 7) with a diameter i of 9.65 mm, inner holes 1216 , which are evenly spaced, with centers 26.7 mm from the center of the central opening 1218 are spaced apart. The middle opening 1218 It has a diameter j of 1.6 cm (5 / 8 inch) and is threaded to attach a lower section 1146 of the piston shaft 1114 to be able to record.

[0192] Before use, the stainless steel grids (not shown) of the piston head piece should be cleaned. 1118 and the cylinder 1120 The device should be checked for blockages, holes, or overstretching and replaced if necessary. A urine permeability tester with a damaged grid can give inaccurate UPM readings and must not be used until the grid has been replaced.

[0193] A 5.00 cm mark 1156is placed at a height k of 5.00 cm (± 0.05 cm) above the grid (not shown), which is on the ground 1148 of the cylinder 1120 The pressure plate is attached. This marks the fluid level that should be maintained during the analysis. Maintaining a correct and constant fluid level (hydrostatic pressure) is critical for measurement accuracy.

[0194] A storage vessel with a constant hydrostatic column, 1014 , is used to make saline solution 1032 to the cylinder 1120 to deliver and the level of the saline solution 1032 to be held at a height k of 5.00 cm above the grid (not shown), which is on the ground 1148 of the cylinder 1120 is appropriate. The floor 1034 of the air supply pipe 1010 is positioned so that the level of the saline solution 1032 in the cylinder 1120during the measurement, the required height k of 5.00 cm can be maintained, i.e., the ground 1034 of the pipe 1010 lies essentially on the same plane 1038 like the 5.00 cm mark 1156 on the cylinder 1120 , since it is on the support grid (not shown) on the ring tripod 1040 above the collection container 1024 It's seated. The proper vertical alignment of the air intake pipe. 1010 and the 5.00 cm mark 1156 on the cylinder 1120 is critical for the analysis. A suitable storage container 1014 consists of a container 1030 , which contains: a horizontally oriented L-shaped feed tube 1018 for fluid supply, a vertically oriented, open-ended pipe 1010 for introducing air at a fixed height within the reservoir with the constant hydrostatic column, 1014 , and a vent fitted with a plug.1012 , to the storage container 1014 to fill with the constant hydrostatic column. The pipe 1010 It has an inner diameter of 12.5 mm ± 0.5 mm. The feed tube 1018 , which is near the ground 1042 of the storage vessel with the constant hydrostatic column 1014 It is arranged and contains a tap 1020 to start / stop the supply of saline solution 1032 The outlet 1044 of the feed pipe 1018 is dimensioned so that it passes through the second lid opening 1136 in the cylinder head 1116 can be inserted, with its end below the surface of the salt solution 1032 in the cylinder 1120 is arranged (after the level of the salt solution 1032 of 5.00 cm in the cylinder 1120 (has been achieved). The air intake pipe 1010It is held in place by an O-ring cuff (not shown). The reservoir with the constant hydrostatic column, 1014 , can be used on a laboratory lifting platform 1016 be arranged to adjust its height relative to that of the cylinder 1120 to be able to adapt. The components of the storage vessel with the constant hydrostatic column, 1014 are dimensioned so that the cylinder 1120 It can be quickly filled to the required height (i.e., hydrostatic column) and this height can be maintained for the duration of the measurement. The reservoir 1014 The constant hydrostatic column must be able to circulate a salt solution. 1032 to be delivered for at least 10 minutes at a flow rate of at least 3 g / s.

[0195] The piston / cylinder arrangement 1028is placed on a rigid 16-mesh stainless steel support grid (not shown) (or an equivalent arrangement) supported by a ring stand ( 1040 ) or a suitable alternative rigid stand. This support grid (not shown) is sufficiently permeable to allow the flow of the saline solution. 1032 It is not obstructed and is sufficiently rigid to support the stainless steel mesh (not shown) to prevent it from stretching. The support mesh (not shown) should be flat and even to prevent the piston / cylinder assembly from being obstructed. 1028 during the test, the device is tilted. 1032 , which passes through the support grid (not shown), is collected in a container 1024 The collected material is positioned below the support grid (not shown) (but does not support it). The collection vessel 1024It is placed on the scale, which measures with an accuracy of at least 0.01 g. The digital output of the scale 1026 is connected to a (not shown) computer-aided data acquisition system. Production of reagents (not shown)

[0196] Jayco Synthetic Urine (JSU) 1312 (see Fig. 13) is used for a swelling phase (see UPM procedure, below) and 0.118 M sodium chloride (NaCl) solution is used for a flow phase (see UPM procedure, below). The following preparations are based on a standard volume of 1 liter. For preparing volumes other than 1 liter, all quantities are scaled up or down accordingly.

[0197] JSU: A 1 L volumetric flask is filled with distilled water to 80% of its volume, and a magnetic stir bar is placed inside the flask. Separately, using a weighing paper or beaker, the following quantities of dry ingredients are weighed to ± 0.01 g using an analytical balance and added quantitatively to the volumetric flask in the same order as listed below. The solution is stirred on a suitable stirring plate until all solids are dissolved, the stirring bar is removed, and the solution is diluted to 1 L with distilled water. A stirring bar is reinserted, and the solution is stirred on a stirring plate for several more minutes.

[0198] Salt quantities for the production of 1 liter of Jayco Synthetic Urine: Potassium chloride (KCl) 2.00 g Sodium sulfate (Na2SO4) 2.00 g Ammonium dihydrogen phosphate (NH4H2PO4) 0.85 g Ammonium phosphate, dibasic ((NH4)2HPO4) 0.15 g Calcium chloride (CaCl2) 0.19 g – [or hydrogenated calcium chloride (CaCl2·2H2O) 0.25 g] Magnesium chloride (MgCl2) 0.23 g – [or hydrogenated magnesium chloride (MgCl2·6H2O) 0.50 g]

[0199] To speed up production, each salt is completely dissolved before the next one is added. Jayco Synthetic Urine can be stored in a clean glass container for 2 weeks. The solution should not be used if it becomes cloudy. Storage time in a clean plastic container is 10 days.

[0200] 0.118 M sodium chloride (NaCl) solution: 0.118 M sodium chloride is used as a salt solution. 1032The following procedure is used: Using paper weights or a beaker, 6.90 g (± 0.01 g) of sodium chloride are weighed and quantitatively transferred to a 1 L volumetric flask; the flask is then filled to its volume with distilled water. A stirring rod is added and the solution is mixed on a stirring plate until all solids are dissolved. Test preparation

[0201] Using a solid cylindrical weight (not shown) (40 mm diameter; 140 mm height), a thickness gauge (not shown) (e.g., Mitotoyo Digimatic Height Gage) is set to zero. This step is best performed on a smooth and level work surface. 1046 executed. The piston / cylinder arrangement 1028 Without superabsorbent polymer particles, the material is positioned under the thickness gauge (not shown) and a measured value L1 is recorded, rounded to the nearest 0.01 mm.

[0202] The storage tank with constant hydrostatic column, 1014 , is treated with saline solution 1032 filled. The ground 1034 of the air intake pipe 1010 is arranged so that the upper part (not shown) of the fluid meniscus (not shown) is in the cylinder 1120 during measurement at the 5.00 cm mark 1156 is maintained. The proper vertical alignment of the air intake pipe. 1010 and the 5.00 cm mark 1156 on the cylinder 1120 is critical for the analysis.

[0203] The collection container 1024 will be placed on the scales 1026 placed, and the digital output of the scale 1026 It is connected to a (not shown) computer-aided data acquisition system. The ring tripod 1040 A 16 mesh stainless steel support grid (not shown) is positioned above the collection vessel. 1024arranged. The (not shown) 16 mesh grid should be sufficiently rigid to support the piston / cylinder arrangement. 1028 to be supported during the measurement. The support grid (not shown) must be flat and level. UPM process

[0204] 1.5 g (± 0.05 g) of superabsorbent polymer particles are weighed onto suitable weighing paper or a weighing aid using an analytical balance. The moisture content of the superabsorbent polymer particles is measured according to the Edana Moisture Content Measurement Method 430.1-99 (“Superabsorbent Materials – Superabsorbent Polyacrylate Powder – Moisture Content – ​​Weight Loss on Heating” (February 1999)). If the moisture content of the superabsorbent polymer particles exceeds 5%, the moisture content of the superabsorbent polymer particles should be corrected (i.e., in this specific case, the added superabsorbent polymer particles should weigh 1.5 g based on their dry weight).

[0205] The empty cylinder 1120 is placed on a flat work surface 1046 positioned and the superabsorbent polymer particles are quantitatively introduced into the cylinder 1120The superabsorbent polymer particles are transferred by gently shaking, rotating, and / or tapping against the cylinder. 120 evenly distributed across the grid (not shown), which is on the ground 1148 of the cylinder 1120 is attached. It is important that the distribution of particles on the grid (not shown), which is on the ground, is 1148 of the cylinder 1120 The surface is uniformly attached to obtain the most accurate result possible. After the superabsorbent polymer particles are evenly distributed on the (not shown) grid, which is attached to the bottom... 1148 of the cylinder 1120 Once attached and distributed, no particles may remain on the inner cylinder walls. 1150 adhere. The piston shaft 1114 is through the first lid opening 1134 inserted through, whereby the lip 1154 of the lid 1116 on the piston head piece 1118 is directed. The piston head piece 1118is carefully inserted into the cylinder to a depth of a few centimeters. 1120 introduced. The lid 1116 will then be moved to the top edge 1144 of the cylinder 1120 set, taking care that the piston crown 1118 The lid does not touch the superabsorbent polymer particles. 1116 and the piston shaft 1126 They are then carefully rotated to align the third, fourth, fifth, and sixth linear index marks. The piston head piece 1118 will then (via the piston shaft) 1114 ) gently lowered until it rests on the dry, superabsorbent polymer particles. The weight 1112 This will be done on the upper section 1128 of the piston shaft 1114 ordered that it be on the paragraph 1124 The lid rests so that the first and second linear index marks align. Proper fit of the lid is essential. 1116prevents seizing and ensures an even distribution of weight on the hydrogel layer. 1318 .

[0206] Swelling phase: A sintered glass disc with a diameter of 8 Cr; (7 mm thick; e.g. Chemglass Inc. No. CG 201-51, coarse-pored) 1310 is achieved by adding JSU 1312 in excess of the sintered glass pane 1310 saturated until the sintered glass pane 1310 is saturated. The saturated sintered glass pane 1310 is placed on a Petri dish 1314 laid with a wide, flat bottom, and JSU 1312 will be added until it reaches the top 1316 the sintered glass pane 1310 The height of the JSU must not exceed the height of the sintered glass pane. 1310 do not exceed.

[0207] The (not shown) grid that is on the ground 1148 of the cylinder 1120Once attached, it can be easily stretched. To prevent stretching, lateral pressure is applied to the piston shaft. 1114 immediately above the lid 1116 applied, specifically with the index finger, while the cylinder 1120 the piston / cylinder arrangement 1028 is gripped. This causes the piston shaft to be gripped. 1114 against the lid 1116 held in place so that the piston / cylinder arrangement 1028 can be lifted without applying too great a force to the (not shown) grid.

[0208] The entire piston / cylinder assembly 1028 is lifted in this way and placed on the sintered glass pane 1310 in the petri dish 1314 posed JSU 1312 from the petri dish 1314 penetrates the sintered glass pane 1310 and is absorbed by the superabsorbent polymer particles (not shown) to form a hydrogel layer 1318to form. The JSU present in the Petri dish 1312 This should be sufficient for the entire swelling phase. If necessary, more JSU can be added during the humidification period. 1312 to the petri dish 1314 to be added to raise the JSU level 1312 on the top 1316 the sintered glass pane 1310 to be maintained. After a period of 60 minutes, the piston / cylinder arrangement will be 1028 from the sintered glass pane 1310 removed, taking care to avoid damaging the piston shaft 1114 against the lid 1116 to hold it in place as described above, and to ensure that the hydrogel layer 1318 no JSU during this process 1312 loses or takes in air. The piston / cylinder arrangement 1028The device is positioned under the (not shown) thickness gauge, and a measured value L2 is recorded, rounded to the nearest 0.01 mm. If the measured value changes over time, only the first value is recorded. The thickness of the hydrogel layer 1318 , L0, is determined from L2 – L1 rounded to the nearest 0.1 mm.

[0209] The piston / cylinder arrangement 1028 is placed on the (not shown) support grid, which is attached to the ring stand 1040 The process is transferred, taking care to protect the piston shaft. 1114 against the lid 1116 to be recorded. The reservoir with the constant hydrostatic column, 1014 , is arranged so that the feed pipe 1018 through the second lid opening 1136 The measurement is initiated in the following sequence: a) The rooster 1020 of the storage tank with the constant hydrostatic column, 1014, is opened so that the salt solution 1032 the 5.00 cm mark 1156 on the cylinder 1120 can reach this level of the saline solution. 1032 should be within 10 seconds of opening the tap 1020 can be achieved. b) As soon as 5.00 cm of saline solution 1032 Once the data collection targets have been reached, the data collection program is initiated.

[0210] With the help of a computer (not shown) attached to the scale 1026 Once attached, the amount of salt solution 1032 , which pass through the hydrogel layer 1318 The pressure is recorded at 20-second intervals for a period of 10 minutes. At the end of the 10 minutes, the tap is turned off. 1020 at the storage container 1014 closed with the constant hydrostatic column.

[0211] The data from 60 seconds until the end of the experiment are used for the RPM calculation. The data collected in the first 60 seconds are not included in the calculation. The flow rate F s (in g / s) is the gradient of a linear MSQ on a graph of the weight of the collected salt solution. 1032 (in grams) as a function of time (in seconds) from 60 to 600 seconds.

[0212] The urine permeability measurement (Q) of the hydrogel layer 1318 is calculated using the following equation: Q = [F g × L0] / [ρ × A × ΔP], where F g The flow rate in g / s is determined from regression analysis of the flow rate results, L0 is the initial thickness of the hydrogel layer. 1318 in cm, ρ the density of the salt solution 1032 in g / cm² 3 A (from the equation above) is the hydrogel layer. 1318 in cm 2 , ΔP is the hydrostatic pressure in dyn / cm² 2, and the urine permeability measurement, Q, is in units of cm. 3 s / gm. The average of three determinations should be given. • FSR testing procedure

[0213] This method determines how quickly superabsorbent polymer particles, especially polymeric hydrogel-forming particles such as cross-linked polyacrylates, swell in 0.9% saline solution (0.9 wt% aqueous NaCl solution). The measurement principle involves allowing the superabsorbent polymer particles to absorb a known amount of fluid and measuring the time required for absorption. The result is then expressed in grams of absorbed fluid per gram of material per second. All tests are performed at 23 ± 2°C.

[0214] Four grams of a typical sample of the superabsorbent polymer particles are dried in an uncovered Petri dish with a diameter of 5 cm in a vacuum chamber at 23 ± 2°C and 1.33 Pa (0.01 Torr) or less for 48 hours prior to measurement.

[0215] Approximately 1 g (+ / - 0.1 g) of the test sample is taken from the vacuum chamber and immediately weighed to the nearest 0.001 g into a 25 ml beaker with an inner diameter of 32 to 34 mm and a height of 50 mm. The material is evenly distributed across the bottom of the beaker. 20 g of 0.9% saline solution are weighed to the nearest 0.01 g into a 50 ml beaker and then carefully but quickly poured into the beaker containing the test material. A timer is started immediately upon contact of the liquid with the material. The beaker is neither moved nor stirred during the swelling process.

[0216] The timer is stopped, and the time at which the last portion of the undisturbed fluid is reached by the swelling particles is recorded to the nearest second (or more precisely, if necessary). To improve the reproducibility of the endpoint determination, the liquid level can be illuminated with a small lamp without heating the surface. The beaker is then weighed again to determine the exact amount of liquid taken up, accurate to ± 0.1 g.

[0217] The free swelling rate is calculated by dividing the weight of the superabsorbent polymer particles by the amount of liquid actually absorbed and dividing the result by the time required for this absorption, expressed in g / g / s. Three measurements are taken and the results are averaged to obtain the FSR value in g / g / s, which is reported to three significant figures. • Flat-field testing procedure

[0218] This method determines how long absorption takes in a baby diaper that is typically designed for wearers weighing between 8 and 13 kg ± 20% (for example, Pampers Active Fit size 4 or other Pampers baby diapers size 4, Huggies baby diapers size 4 or baby diapers size 4 of most other brands). device

[0219] The test device is in Fig. 14 is shown and features a tub 1411 on, which consists of polycarbonate (e.g. Lexan) ® ) and has a nominal thickness of 12.5 mm (0.5 inch). The tub 1411 has a straight horizontal base 1412 with a length of 508 mm (20.0 inches) and a width of 152 mm (6.0 inches). Two straight vertical sides. 1413 With a height of 64 mm (2.5 inches) × a length of 508 mm (20 inches), the long edges of the base 1412attached to form a U-shaped tub 1411 to form a tub with a length of 508 mm (20.0 inches), an internal width of 152 mm (6.0 inches), and an internal depth of 51 mm (2.0 inches). The front and rear ends of the tub 1411 are not enclosed.

[0220] A piece of open-cell polyurethane foam 1414 With dimensions of 508 × 152 × 25 mm, it is wrapped in polyethylene film and placed on the bottom of the tub. 1411 laid out so that the edges of the foam 1414 and the bathtub 1411 are aligned with each other and the top surface of the polyethylene film is smooth and free of seams, creases, or defects. The polyurethane foam 1414It has a pressure modulus of 31 kPa (0.48 psi). A reference line is drawn across the width of the top surface of the polyethylene cover at a distance of 152 mm (6.0 inches) from one end (the front edge) parallel to the transverse center line using a smudge-proof marker.

[0221] A straight polycarbonate top panel 1415 It has a nominal thickness of 12.5 mm (0.5 in), a length of 508 mm (20.0 in), and a width of 146 mm (5.75 in). A 51 mm (2.0 in) diameter hole is drilled in the center of the top plate. 1415 drilled (i.e., the center of the hole is located at the intersection of the longitudinal and transverse axes of the top of the top plate) 1415 A polycarbonate cylinder 1416 With an outer diameter of 51 mm (2.0 inch), an inner diameter of 37.5 mm (1.5 inch) and a height of 102 mm (4.0 inch), it is inserted into the hole in the cover plate. 1415glued so that the lower edge of the cylinder 1416 is flush with the underside of the top plate 1415 and the cylinder 1416 vertically by 89 mm (3.5 inches) above the top of the top plate 1415 protrudes and the joint between the cylinder 1416 and the top plate 1415 It is waterproof. It has a ring-shaped recess. 1417 With a height of 2 mm and a diameter of 44.5 mm (1.75 inches), it is inserted into the lower inner rim of the cylinder. 1416 The process involved drilling two holes, each with a diameter of 1 mm, at a 45° angle to the top surface of the top plate. 1415 drilled so that the holes penetrate the inner surface of the cylinder 1416 immediately above the recess 1417 cut and on opposite sides of the cylinder 1416 lie (i.e., are 180° apart). Two stainless steel wires 1418 with a diameter of 1 mm, they are inserted into the holes in a waterproof manner.1415 glued so that one end of each wire is flush with the inner wall of the cylinder and the other end is on the top of the top plate 1415 These wires protrude. These wires will be referred to as electrodes in the following. A reference line is drawn across the width of the top plate. 1415 Drawn 152 mm (6.0 inches) from the front edge, parallel to the transverse center line. The arrangement of the top plate 1415 / Cylinder 1416 It weighs approximately 1180 grams.

[0222] Two steel weights, each weighing 9.0 kg and measuring 146 mm (5.75 inches) wide, 76 mm (3.0 inches) deep and approximately 100 mm (4 inches) high, are also required. Procedure:

[0223] All tests are performed at 23 ± 2°C and 35 ± 15% relative humidity.

[0224] The polycarbonate tub 1411 , which the wrapped piece of foam 1414The product is placed on a suitable flat, horizontal surface. A disposable absorbent product is removed from its packaging, and the elastic cuff is cut at appropriate intervals so that the product can be laid flat. The product is weighed on a suitable top-loading scale to an accuracy of ± 0.1 grams and then placed on the covered piece of foam. 1414 The product is placed in the receiving device, with its front waist edge aligned with the reference mark on the polyethylene cover. The product is centered along the longitudinal center line of the device, with the top layer (the side facing the body) of the product facing upwards and the rear waist edge towards the rear end of the foam piece. 1414 Look. The cover plate 1415It is placed on the product so that the protruding cylinder points upwards. The attached reference line is aligned with the front waist edge of the product and the rear end of the top plate. 1415 is attached to the rear edge of the foam piece 1414 aligned. The two 9.0 kg weights can be carefully placed on the top plate. 1415 It was arranged so that the width of each weight is parallel to the transverse center line of the top plate and each weight is 83 mm (3.25 inches) from the front or rear edge of the top plate. 1415 is removed.

[0225] The two electrodes are connected to each other via a suitable electrical circuit in order to detect the presence of an electrically conductive fluid between them.

[0226] A suitable pump; e.g., model 7520-00, available from Cole Parmer Instruments, Chicago, USA, or an equivalent device; is used to deliver 0.09 wt% aqueous sodium chloride solution through a flexible plastic tube with an inner diameter of 4.8 mm (3 / 16 inch), e.g., Tygon. ® R-3603 or an equivalent device is used. The end section of the tube is clamped vertically so that it is inside the cylinder. 1416 , which is attached to the top plate 1415 is attached, is centered, with the feed end of the tube pointing downwards and 50 mm (2 inches) below the top edge of the cylinder 1416 The pump is arranged in a timer-controlled manner and is pre-calibrated to deliver a 75.0 ml surge of 0.9% saline solution at a rate of 15 ml / s.

[0227] The pump is activated and a timer starts immediately after activation. The pump delivers 75 ml of 0.9% NaCl solution into the cylinder at a rate of 15 ml / s. 1416 and then stops. When test fluid enters the cylinder 1416 When the fluid is introduced, it typically collects to some extent at the top of the absorption structure. This fluid completes an electrical circuit between the two electrodes in the cylinder. After the initial surge is released, the meniscus of the solution lowers as the fluid is absorbed into the structure. The time is recorded when the circuit is broken because no more free fluid is present between the electrodes in the cylinder.

[0228] The recording time for a specific surge is the time interval between activation of the pump for that surge and the point at which the circuit is interrupted.

[0229] Four surges are delivered in this manner; each surge comprises 78 ml and is delivered at a rate of 15 ml / s. The time interval between the start of each surge is 300 seconds.

[0230] The recording time for four surges is recorded. Three products are tested in this way, and the average surge duration for each surge (for the first to fourth) is calculated. Examples

[0231] Absorption structures according to the present disclosure were fabricated to compare their properties with those of prior art absorption structures. All tested absorption structures comprise superabsorbent polymer particles arranged between two layers of nonwoven support material. For the data presented in Table 1, all samples were taken from an absorption core. The samples correspond to the section of the absorption core of a size 4 absorption article centered on the article's longitudinal centerline, 152 mm from the article's front waist edge. In the section of the absorption core where the samples are taken, the absorption structures of Examples 1 and 2 and Comparison Examples 1 and 2 have the same structure. They differ only in the superabsorbent polymer particles used.For the data shown in Table 2, the total absorption structures of Example 2 and of the comparison examples 1 and 2 have the same structure and differ only in terms of the superabsorbent polymer particles used. • Comparison example 1

[0232] An absorption structure is used that incorporates the same superabsorbent polymer particles as those used in Pampers Active Fit diapers, which were available in the UK in August 2010. These superabsorbent polymer particles are generally manufactured according to US 2009 / 0275470 A1. Note that the superabsorbent polymer particles can be isolated from commercially available Pampers Active Fit diapers as described in European Patent Application No. 10154618.2 entitled “Method of separating superabsorbent polymer particles from a solidified thermoplastic composition comprising polymers”.

[0233] The standard particle size distribution of the superabsorbent polymer particles is 45 to 710 μm with at most 1% below 45 μm and at most 1% above 710 μm. • Comparison example 2

[0234] 300 g of superabsorbent polymer particles were produced according to Comparative Example 11, disclosed in PCT application WO 2010 / 095427 A1 entitled “Polyacrylic acid-based water-absorbing resin powder and method for producing the same”. An absorption structure comprising superabsorbent polymer particles was produced. • Example 1

[0235] 4000 kg of superabsorbent polymer particles from Comparative Example 1 were sieved through a stainless steel wire screen, AISI 304 standard 300 μm, into a vibrating screen with a capacity of approximately 100–150 kg per hour, yielding 750 kg of superabsorbent polymer particles with a mean diameter (D50) of approximately 180–200 μm and a particle size distribution of 45 to 300 μm with at most 3% below 45 μm and at most 3% above 300 μm. An absorption structure comprising these superabsorbent polymer particles was fabricated. • Example 2

[0236] 300 g of superabsorbent polymer particles were produced according to Comparative Example 9, disclosed in PCT application WO 2010 / 095427 A1 entitled “Polyacrylic acid-based water-absorbing resin powder and method for producing the same”. An absorption structure comprising these superabsorbent polymer particles was produced.

[0237] Several parameters of the absorption structures of Examples 1 and 2 and of the comparison examples 1 and 2 were measured: the time to uptake of 20 g / g (T20), the uptake at 20 min (U20), the time to reach 80% uptake of U20 (T80), the effective permeability at 20 minutes (K20), and the temporary gel blocking index (Kmin / K20) were measured according to the K(t) test procedure described above. The UPM (urine permeability) of the superabsorbent polymer particles of the absorption structures of Examples 1 and 2 and of the comparison examples 1 and 2 was measured according to the UPM test procedure described above. The CRC (centrifuge retention capacity) of the superabsorbent polymer particles was measured according to the EDANA procedure WSP 241.2-05.

[0238] Fig. 18A and Fig.Figure 18B shows the uptake in g / g as a function of time for the absorption structures of comparison examples 1 and 2 vs. examples 1 and 2, measured using the K(t) test procedure described above.

[0239] The different values ​​for the measured parameters are summarized in the table below. Table 1 Examples T20(s) U20 (g / g) T80% (g / g) K20 (cm 2 ) Kmin / K20 UPM (1 × 10 27 (cm 3 ·s) / g) CRC (g / g) Comparative example 1 495 23,8 414 3,43·10 –8 0,92 98 26,5 Comparative example 2 477 24,1 410 4,75 · 10 8 0,96 110 27,3 Example 1 200 23,9 177 2,8·10- 8 0,72 66 24,1 Example 2 344 25,0 343 3,13·10 8 0,86 100 27,7

[0240] As from Fig. 18A and Fig. As can be seen from Figure 18B and Table 1, the times to uptake of 20 g / g (T20), measured using the K(t) test procedure, are significantly shorter for the absorption structures fabricated according to Examples 1 and 2 than for the absorption structures fabricated according to Comparison Examples 1 and 2. Therefore, these absorption structures are able to rapidly absorb liquid, even when dry, i.e., when first exposed to liquid.

[0241] Table 1 also shows that superabsorbent polymer particles with a high permeability at equilibrium (a high UPM value), such as the superabsorbent polymer particles of the absorption structures in comparison examples 1 and 2, do not automatically lead to a high T20 value for the absorption structure containing such superabsorbent polymer particles. This means that the permeability at equilibrium of the superabsorbent polymer particles is not a reliable criterion for selecting the absorption structures that are able to rapidly absorb the liquid upon initial exposure. • Absorption times of diapers comprising an absorption structure that includes the superabsorbent polymer particles of Comparative Examples 1 and 2, vs. diapers comprising an absorption structure that includes the superabsorbent polymer particles according to the present disclosure.

[0242] Absorption times of Pampers Active Fit size 4 diapers, available in the UK in August 2010, were measured using the flat absorption test procedure described above. These diapers contain an absorbent core comprising the superabsorbent polymer particles of Comparison Example 1. Absorption times of the same diapers, in which the absorbent core was replaced with one having the same structure but in which the superabsorbent polymer particles were replaced with the superabsorbent polymer particles of Comparison Example 2 or Example 3, were measured using the flat absorption test procedure described above. The absorbent cores of all diapers had a dry thickness of 1.7 mm at the crotch point of the diaper, as measured using the thickness measurement test procedure described above. The absorption times obtained for all samples are summarized in Table 2 below. Table 2 Samples Comparative example Comparative example 2 Example 2 Absorption time for the first surge (75 ml) in seconds 30 28 26

[0243] It can be seen from Table 2 above that the first surge absorption times for diapers comprising an absorption core containing superabsorbent polymer particles according to comparison examples 1 or 2 are longer than the first surge absorption time for the same diaper where the superabsorbent polymer particles have been replaced by the superabsorbent polymer particles of example 2.

[0244] Thus, absorption articles according to the present invention, that is, absorption articles having an absorption structure in which one or more sections of the absorption structure comprise at least 90% superabsorbent polymer particles and require a time to achieve an uptake of 20 g / g (T20) of less than 440 s, as measured by the K(t) test method, exhibit improved absorption properties, particularly during the first surge, i.e., when the article is first wetted.

[0245] The dimensions and values ​​disclosed herein are not to be understood as being strictly limited to the exact numerical values ​​stated. Instead, unless otherwise specified, each such dimension is to mean both the stated value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is to mean "approximately 40 mm".

Claims

[1] Absorbent article comprising an absorption structure, wherein the absorption article is divided into three sections: a front section, a rear section and a step section located between the front section and the rear section, wherein the absorption structure comprises an absorption core, the absorption core having a dry thickness of 0.2 to 5 mm at the step point of the article, wherein one or more sections of the absorption structure comprise at least 90 wt.% superabsorbent polymer particles and require a time to uptake of 20 g / g (T20) of less than 440 s as measured by the K(t) test method. [2] Absorption article according to claim 1, wherein one of the one or more sections of the absorption structure is centered in the middle of the front section of the article and / or one of the one or more sections of the absorption structure is centered at the step section of the article. [3] Absorption article according to one of the preceding claims, wherein the absorption article further comprises a top layer and a bottom layer, wherein the absorption core is arranged between the top layer and the bottom layer. [4] Absorption article according to one of the preceding claims, wherein one or more sections of the absorption structure have an effective permeability at 20 minutes (K20) of at least 2.9·10 –8 cm 2 exhibits, as measured by the K(t) test procedure. [5] Absorption article according to one of the preceding claims, wherein the uptake of one or more sections of the absorption structure at 20 minutes (U20) is at least 24 g / g, as measured by the K(t) test method. [6] Absorption article according to any of the preceding claims, wherein the absorption core is free of airfelt. [7] Absorption article according to any of the preceding claims, wherein the absorption core has an average amount of superabsorbent polymer particles per surface of the absorption core of 200 to 900 g / m² 2 in the crotch area of ​​the article. [8] Absorption article according to any of the preceding claims, wherein the absorption article has a first surge absorption time of less than 27 s, as measured by the flat-field absorption test method. [9] Absorption article according to one of the preceding claims, wherein the superabsorbent polymer particles are enclosed in the absorption core such that the superabsorbent polymer particles are arranged between a first and a second support material layer, wherein the first support material layer faces the lower layer and the second support material layer faces the upper layer. [10] Absorption article according to claim 9, wherein the superabsorbent polymer particles are immobilized by thermoplastic adhesive material. [11] Absorption article according to any one of claims 1 to 8, wherein the absorption core comprises a first carrier material layer, wherein at least a part of the superabsorbent polymer particles are applied to the first carrier material and thermoplastic adhesive material immobilizes the superabsorbent polymer particles. [12] Absorption article according to claim 11, wherein the absorption core further comprises a second carrier material layer, wherein at least a part of the superabsorbent polymer particles are applied to the second carrier material layer and thermoplastic adhesive material immobilizes the superabsorbent polymer particles, wherein the first and second carrier material layers are combined with each other, such that at least a part of the thermoplastic adhesive material of the first carrier material layer contacts at least a part of the thermoplastic adhesive material of the second carrier material layer. [13] Absorption article according to any one of claims 10 to 12, wherein the thermoplastic adhesive material forms a fibrous network over the superabsorbent polymer particles. [14] Absorption article according to one of the preceding claims, wherein at least one of the one or more sections of the absorption structure has a surface area of ​​30 cm² 2 or more. [15] Absorption article according to claim 14, wherein at least one of the one or more sections of the absorption structure has a surface area of ​​30 cm² 2 or more, enclosing a circular area.