WO2014019813A1

WO2014019813A1 - Odour-inhibiting mixtures for incontinence products

Info

Publication number: WO2014019813A1
Application number: PCT/EP2013/064412
Authority: WO
Inventors: Asif Karim; Thomas Daniel
Original assignee: Basf Se; Basf Schweiz Ag
Priority date: 2012-07-30
Filing date: 2013-07-08
Publication date: 2014-02-06

Abstract

The invention relates to odour-inhibiting mixtures containing water-absorbing polymer particles and irregular, low-dust activated carbon for use in incontinence products.

Description

Odor-inhibiting mixtures for incontinence articles

The present invention relates to odor-inhibiting mixtures containing water-absorbing polymer particles and irregular, low-dust activated carbon for use in incontinence articles.

Water-absorbing polymer particles are used for the production of diapers, tampons, feminine pads and other hygiene articles, but also as water-retaining agents in agricultural horticulture. The water-absorbing polymer particles are also referred to as superabsorbers.

The preparation of water-absorbing polymer particles is described in the monograph "Modern Superabsorbent Polymer Technology", F.L. Buchholz and AT. Graham, Wiley-VCH, 1998, pages 71-103.

The properties of the water-absorbing polymer particles can be adjusted, for example, via the amount of crosslinker used. As the amount of crosslinker increases, the centrifuge retention capacity (CRC) decreases and the absorption under a pressure of 21.0 g / cm ² (AUL 0.3 psi) goes through a maximum.

To improve the application properties, such as permeability of the swollen gel bed (SFC) in the diaper and absorption under a pressure of 49.2 g / cm ²

(AUL0.7psi), water-absorbing polymer particles are generally surface-postcrosslinked. As a result, the degree of crosslinking of the particle surface increases, whereby the absorption under a pressure of 49.2 g / cm ² (AUL0.7 psi) and the centrifuge retention capacity (CRC) can be at least partially decoupled. This surface postcrosslinking can be carried out in aqueous gel phase. Preferably, however, dried, ground and sieved polymer particles (base polymer) are coated on the surface with a surface postcrosslinker and thermally surface postcrosslinked. Crosslinkers suitable for this purpose are compounds which can form covalent bonds with at least two carboxylate groups of the water-absorbing polymer particles. There has also been no lack of attempts to prevent the formation of unpleasant odors in the application of hygiene articles. According to US 2008/0179 A1, US 2008/0147028 A1, US 2010/0286645 A1, EP 1 358 894 A1 and WO 98/26808 A2, for example activated carbon can be used for this purpose. The object of the present invention was to provide improved odor-inhibiting mixtures for use in incontinence articles. The mixtures should in particular have a higher degree of whiteness. Furthermore, the system components used to produce the odor-inhibiting mixtures should be easy to clean, so that contamination of the subsequent production campaign is avoided when changing products. The object has been achieved by odor-inhibiting mixtures comprising water-absorbing polymer particles and irregular charcoal particles having a dust number of less than 50, preferably less than 45, more preferably less than 40, most preferably less than 35. Activated carbon is usually used as powder, crushed particles or rod-shaped Used compacts. The irregular activated carbon particles according to the invention are particularly low-dust activated carbon. Such particularly low-dust activated carbons are commercially available, for example Norit GCN3070 (Norit Nederland BV, Amersfoort, The Netherlands). The water-absorbing polymer particles are obtained, for example, by polymerization of a monomer solution or suspension comprising a) at least one ethylenically unsaturated, acid group-carrying monomer which may be at least partially neutralized,

b) at least one crosslinker,

c) at least one initiator,

d) optionally one or more copolymerizable with the monomers mentioned under a) ethylenically unsaturated monomers and

e) optionally one or more water-soluble polymers, prepared and are usually water-insoluble.

The monomers a) are preferably water-soluble, i. the solubility in water at 23 ° C. is typically at least 1 g / 100 g of water, preferably at least 5 g / 100 g of water, more preferably at least 25 g / 100 g of water, most preferably at least 35 g / 100 g of water.

Suitable monomers a) are, for example, ethylenically unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, and itaconic acid. Particularly preferred monomers are acrylic acid and methacrylic acid. Very particular preference is given to acrylic acid.

Further suitable monomers a) are, for example, ethylenically unsaturated sulfonic acids, such as styrenesulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid (AMPS).

Impurities can have a significant influence on the polymerization. Therefore, the raw materials used should have the highest possible purity. It is therefore often advantageous to purify the monomers a) specifically. Suitable cleaning methods are exemplified as described in WO 2002/055469 A1, WO 2003/078378 A1 and WO 2004/035514 A1. A suitable monomer a) is, for example, an acrylic acid purified according to WO 2004/035514 A1 with 99.8460% by weight of acrylic acid, 0.0950% by weight of acetic acid,

0.0332% by weight of water, 0.0203% by weight of propionic acid, 0.0001% by weight of furfurals, 0.0001% by weight of maleic anhydride, 0.0003% by weight of diacrylic acid and 0.0050 part by weight of % Hydroquinone monomethyl ether.

The proportion of acrylic acid and / or salts thereof in the total amount of the monomers is preferably at least 50 mol%, particularly preferably at least 90 mol%, very particularly preferably at least 95 mol%.

The acrylic acid used usually contains polymerization inhibitors, preferably hydraquinone half ethers, as a storage stabilizer. The monomer solution therefore preferably contains up to 250 ppm by weight, preferably at most 130 ppm by weight, more preferably at most 70 ppm by weight, preferably at least 10 ppm by weight, particularly preferably at least 30 ppm by weight, in particular by 50 Ppm by weight, hydroquinone half ether, in each case based on the unneutralized acrylic acid. For example, an acrylic acid having a corresponding content of hydroquinone half-ether can be used to prepare the monomer solution.

Preferred hydroquinone half ethers are hydroquinone monomethyl ether (MEHQ) and / or alpha tocopherol (vitamin E). Suitable crosslinkers b) are compounds having at least two groups suitable for crosslinking. Such groups are, for example, ethylenically unsaturated groups which can be radically copolymerized into the polymer chain, and functional groups which can form covalent bonds with the acid groups of the acrylic acid. Furthermore, polyvalent metal salts which can form coordinate binding with at least two acid groups of the acrylic acid are also suitable as crosslinking agents b).

Crosslinkers b) are preferably compounds having at least two polymerizable groups which can be incorporated in the polymer network in free-radically polymerized form. Suitable crosslinkers b) are, for example, ethylene glycol dimethacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, allyl methacrylate, trimethylolpropane triacrylate, triallylamine, tetraallylammonium chloride, tetraallyloxyethane, as described in EP 0 530 438 A1, di- and triacrylates, as in EP 0 547 847 A1, EP 0 559 476 A1, EP 0 632 068 A1, WO 93/21237 A1, WO 2003/104299 A1, WO 2003/104300 A1, WO 2003/104301 A1 and DE 103 31 450 A1, mixed acrylates which, in addition to acrylate groups, contain further ethylenically unsaturated Groups, as described in DE 103 31 456 A1 and DE 103 55 401 A1, or crosslinker mixtures, as described, for example, in DE 195 43 368 A1, DE 196 46 484 A1, WO 90/15830 A1 and WO 2002/032962 A2. Preferred crosslinkers b) are pentaerythritol triallyl ether, tetraallyloxyethane, methylenebismethacrylamide, 15-tuply ethoxylated trimethylolpropane triacrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate and triallylamine.

Very particularly preferred crosslinkers b) are the polyethyleneglyoxylated and / or propoxylated glycerols esterified with acrylic acid or methacrylic acid to form diioder triacrylates, as described, for example, in WO 2003/104301 A1. Particularly advantageous are di- and / or triacrylates of 3- to 10-fold ethoxylated glycerol. Very particular preference is given to diacrylates or triacrylates of 1 to 5 times ethoxylated and / or propoxylated glycerol. Most preferred are the triacrylates of 3 to 5 times ethoxylated and / or propoxylated glycerol, in particular the triacrylate of 3-times ethoxylated glycerol.

The amount of crosslinker b) is preferably from 0.05 to 1, 5 wt .-%, particularly preferably 0.1 to 1 wt .-%, most preferably 0.2 to 0.6 wt .-%, each based on acrylic acid. With increasing crosslinker content, the centrifuge retention capacity (CRC) decreases and the absorption under a pressure of 21.0 g / cm ² passes through a maximum.

As initiators c) it is possible to use all compounds which generate radicals under the polymerization conditions, for example thermal initiators, redox initiators, photoinitiators. Suitable redox initiators are sodium peroxodisulfate / ascorbic acid, hydrogen peroxide / ascorbic acid, sodium peroxodisulfate / sodium bisulfite and hydrogen peroxide / sodium bisulfite. Preferably, mixtures of thermal initiators and redox initiators are used, such as sodium peroxodisulfate / hydrogen peroxide / ascorbic acid. As a reducing component but is preferably a mixture of the sodium salt of 2

Hydroxy-2-sulfinatoacetic acid, the disodium salt of 2-hydroxy-2-sulfonatoacetic acid and sodium bisulfite used. Such mixtures are available as Brüggolite® FF6 and Brüggolite® FF7 (Brüggemann Chemicals, Heilbronn, Germany). Acrylic acid-copolymerizable ethylenically unsaturated monomers d) are, for example, acrylamide, methacrylamide, hydroxyethyl acrylate, hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminopropyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate. As water-soluble polymers e) it is possible to use polyvinyl alcohol, polyvinylpyrrolidone, starch, starch derivatives, modified cellulose, such as methylcellulose or hydroxyethylcellulose, gelatin, polyglycols or polyacrylic acids, preferably starch, starch derivatives and modified cellulose. Usually, an aqueous monomer solution is used. The water content of the monomer solution is preferably from 40 to 75% by weight, more preferably from 45 to 70% by weight, most preferably from 50 to 65% by weight. It is also possible monomer suspensions NEN, ie monomer solutions with excess acrylic acid, for example, sodium, use. With increasing water content, the energy expenditure increases during the subsequent drying and with decreasing water content, the heat of polymerization can only be dissipated insufficiently.

The preferred polymerization inhibitors require dissolved oxygen for optimum performance. Therefore, the monomer solution may be polymerized prior to polymerization by inerting, i. Flow through with an inert gas, preferably nitrogen or carbon dioxide, are freed of dissolved oxygen. The oxygen content of the monomer solution prior to the polymerization is preferably reduced to less than 1 ppm by weight, more preferably to less than 0.5 ppm by weight, very particularly preferably to less than 0.1 ppm by weight.

Suitable reactors are, for example, kneading reactors or belt reactors. In the kneader, the polymer gel resulting from the polymerization of an aqueous monomer solution or suspension is continuously comminuted by, for example, counter-rotating stirring shafts, as in

WO 2001/038402 A1. The polymerization on the belt is described, for example, in DE 38 25 366 A1 and US Pat. No. 6,241,928. During the polymerization in a belt reactor, a polymer gel is formed, which must be comminuted in a further process step, for example in an extruder or kneader.

In order to improve the drying properties, the comminuted polymer gel obtained by means of a kneader may additionally be extruded.

The acid groups of the polymer gels obtained are usually partially neutralized. The neutralization is preferably carried out at the stage of the monomers. This is usually done by mixing the neutralizing agent as an aqueous solution or preferably as a solid. The degree of neutralization is preferably from 25 to 95 mol%, particularly preferably from 30 to 80 mol%, very particularly preferably from 40 to 75 mol%, wherein the customary neutralizing agents can be used, preferably alkali metal hydroxides, alkali metal oxides, alkali metal carbonates or Alkalimetallhydrogenkarbonate and mixtures thereof. Instead of alkali metal salts and ammonium salts can be used. Sodium and potassium are particularly preferred as alkali metals, but most preferred are sodium hydroxide, sodium carbonate or sodium bicarbonate and mixtures thereof.

But it is also possible to carry out the neutralization after the polymerization at the stage of Polymergeis formed during the polymerization. Furthermore, it is possible to neutralize up to 40 mol%, preferably 10 to 30 mol%, particularly preferably 15 to 25 mol%, of the acid groups before the polymerization by adding a part of the neutralizing agent already to the monomer solution and the desired final degree of neutralization only after the polymerization is adjusted at the stage of Polymergeis. If the polymer gel is at least partially neutralized after the polymerization, the polymer gel is preferably mechanical comminuted, for example by means of an extruder, wherein the neutralizing agent can be sprayed on, sprinkled or poured and then mixed thoroughly. For this purpose, the gel mass obtained can be extruded several times for homogenization.

The polymer gel is then preferably dried with a belt dryer until the residual moisture content is preferably from 0.5 to 15% by weight, particularly preferably from 1 to 10% by weight, very particularly preferably from 2 to 8% by weight, where Residual moisture content according to the test method No. WSP 230.2-05 "Mass Loss Upon Heating" recommended by the EDA-NA. If the residual moisture content is too high, the dried polymer gel has too low a glass transition temperature T _g and is difficult to process further. If the residual moisture is too low, the dried polymer gel is too brittle, and in the subsequent comminution steps undesirably large quantities of polymer particles with too small particle size ("fines") are produced. %, particularly preferably from 35 to 70% by weight, very particularly preferably from 40 to 60% by weight. Optionally, however, a fluidized bed dryer or a bubble dryer can also be used for the drying.

The dried polymer gel is then ground and classified, wherein for grinding usually one- or multi-stage roller mills, preferably two- or three-stage roller mills, pin mills, hammer mills or vibratory mills, can be used.

In a preferred embodiment of the present invention, an aqueous monomer solution is dripped off and the drops produced are polymerized in a heated carrier gas stream. Here, the process steps polymerization and drying can be summarized, as in WO 2008/040715 A2, in WO 2008/052971 A1 and in particular in WO

201 1/026876 A1. In this preferred embodiment, the particle size is adjusted by the size of the drops produced.

The mean particle size of the water-absorbing polymer particles is preferably at least 200 .mu.m, more preferably from 250 to 600 .mu.m, very particularly from 300 to 500 .mu.m. The average particle size can be determined by means of the EDANA recommended test method No. WSP 220.2-05 "Particle Size Distribution", in which the mass fractions of the sieve fractions are applied cumulatively and the average particle size is determined graphically. The mean particle size here is the value of the mesh size, which results for accumulated 50 wt .-%.

The proportion of particles having a particle size of greater than 150 μm is preferably at least 90% by weight, particularly preferably at least 95% by weight, very particularly preferably at least 98% by weight. Polymer particles with too small particle size lower the permeability (SFC). Therefore, the proportion of too small polymer particles ("fines") should be low. Too small polymer particles are therefore usually separated and recycled to the process. This preferably takes place before, during or immediately after the polymerization, ie before the drying of the polymer gel. The too small polymer particles can be moistened with water and / or aqueous surfactant before or during the recycling.

It is also possible to separate small polymer particles in later process steps, for example after surface postcrosslinking or another coating step. In this case, the recycled too small polymer particles are surface postcrosslinked or otherwise coated, for example with fumed silica. If a kneading reactor is used for the polymerization, the too small polymer particles are preferably added during the last third of the polymerization.

If the polymer particles which are too small are added very early, for example already to the monomer solution, this lowers the centrifuge retention capacity (CRC) of the water-absorbing polymer particles obtained. However, this can be compensated for example by adjusting the amount of crosslinker b).

If the polymer particles which are too small are added very late, for example only in an apparatus downstream of the polymerization reactor, for example an extruder, then the polymer particles which are too small can only be incorporated into the resulting polymer gel with difficulty. Insufficiently incorporated too small polymer particles, however, dissolve again during the grinding of the dried polymer gel, are therefore separated again during classification and increase the amount of recycled too small polymer particles. The proportion of particles having a particle size of at most 850 μm, is preferably at least 90% by weight, particularly preferably at least 95% by weight, very particularly preferably at least 98% by weight.

The proportion of particles having a particle size of 150 to 850 μmηη is preferably at least 90 wt .-%, more preferably at least 95 wt .-%, most preferably at least 98 wt .-%.

Polymer particles with too large particle size reduce the swelling rate. Therefore, the proportion of polymer particles too large should also be low.

Too large polymer particles are therefore usually separated and recycled to the grinding of the dried Polymergeis.

The polymer particles can be surface-post-crosslinked to further improve the properties. Suitable surface postcrosslinkers are compounds containing groups that can form covalent bonds with at least two carboxylate groups of the polymer particles. Suitable compounds are, for example, polyfunctional amines, polyfunctional Amidoamines, polyfunctional epoxides, as described in EP 0 083 022 A2, EP 0 543 303 A1 and EP 0 937 736 A2, di- or polyfunctional alcohols, as in DE 33 14 019 A1, DE 35 23 617 A1 and EP 0 450 922 A2, or β-hydroxyalkylamides, as described in DE 102 04 938 A1 and US 6,239,230.

Furthermore, in DE 40 20 780 C1 cyclic carbonates, in DE 198 07 502 A1 2- oxazolidinone and its derivatives, such as 2-hydroxyethyl-2-oxazolidinone, in DE 198 07 992 C1 bis- and poly-2-oxazolidinone, in DE 198 54 573 A1 2-oxotetrahydro-1,3-oxazine and its derivatives, in DE 198 54 574 A1 N-acyl-2-oxazolidinones, in DE 102 04 937 A1 cyclic ureas, in DE 103 34 584 A1 bicyclic Amidoacetals, described in EP 1 199 327 A2 oxetanes and cyclic ureas and in WO 2003/031482 A1 morpholine-2,3-dione and its derivatives as suitable surface postcrosslinkers.

Preferred surface postcrosslinkers are ethylene carbonate, ethylene glycol diglycidyl ether, reaction products of polyamides with epichlorohydrin and mixtures of propylene glycol and 1,4-butanediol.

Very particularly preferred surface postcrosslinkers are 2-hydroxyethyl-2-oxazolidinone, 2-oxazolidinone and 1, 3-propanediol.

Furthermore, it is also possible to use surface postcrosslinkers which contain additional polymerizable ethylenically unsaturated groups, as described in DE 37 13 601 A1

The amount of surface postcrosslinker is preferably 0.001 to 2 wt .-%, more preferably 0.02 to 1 wt .-%, most preferably 0.05 to 0.2 wt .-%, each based on the polymer particles.

In a preferred embodiment of the present invention, polyvalent cations are applied to the particle surface before, during or after the surface postcrosslinking in addition to the surface postcrosslinkers.

The polyvalent cations which can be used in the process according to the invention are, for example, divalent cations, such as the cations of zinc, magnesium, calcium, iron and strontium, trivalent cations, such as the cations of aluminum, iron, chromium, rare earths and manganese, tetravalent cations, such as Cations of titanium and zirconium. As a counterion, hydroxide, chloride, bromide, sulfate, hydrogen sulfate, carbonate, bicarbonate, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate and carboxylate, such as acetate, citrate and lactate, are possible. It is also possible to use salts with different counterions, for example basic aluminum salts, such as aluminum monoacetate or aluminum monolactate. Aluminum sulfate, aluminum monoacetate and aluminum lactate are preferred. Apart from metal salts, polyamines can also be used as polyvalent cations. The amount of polyvalent cation used is, for example, 0.001 to 1.5% by weight, preferably 0.005 to 1% by weight, particularly preferably 0.02 to 0.8% by weight. in each case based on the polymer particles. The surface postcrosslinking is usually carried out so that a solution of the surface postcrosslinker is sprayed onto the dried polymer particles. Subsequent to the spraying, the polymer coated with surface postcrosslinker are thermally dried, whereby the surface postcrosslinking reaction can take place both before and during drying.

The spraying of a solution of the surface postcrosslinker is preferably carried out in mixers with moving mixing tools, such as screw mixers, disk mixers and paddle mixers. Particularly preferred are horizontal mixers, such as paddle mixers, very particularly preferred are vertical mixers. The distinction between horizontal mixer and vertical mixer is made by the storage of the mixing shaft, i. Horizontal mixers have a horizontally mounted mixing shaft and vertical mixers have a vertically mounted mixing shaft. Suitable mixers are, for example, Horizontal Pflugschar® mixers (Gebr. Lödige Maschinenbau GmbH, Paderborn, Germany), Vrieco-Nauta Continuous Mixer (Hosokawa Micron BV, Doetinchem, the Netherlands), Processall Mixmill Mixer (Processall Incorporated; Cincinnati, USA) and Schugi Flexomix® (Hosokawa Micron BV, Doetinchem, The Netherlands). However, it is also possible to spray the surface postcrosslinker solution in a fluidized bed.

The surface postcrosslinkers are typically used as an aqueous solution. The amount of non-aqueous solvent or total solvent can be used to adjust the penetration depth of the surface postcrosslinker into the polymer particles.

If only water is used as the solvent, it is advantageous to add a surfactant. As a result, the wetting behavior is improved and the tendency to clog is reduced. However, preference is given to using solvent mixtures, for example isopropanol / water, 1,3-propanediol / water and propylene glycol / water, the mixing mass ratio preferably being from 20:80 to 40:60.

The thermal drying is preferably carried out in contact dryers, more preferably paddle dryers, very particularly preferably disk dryers. Suitable dryers are, for example, Hosokawa Bepex® Horizontal Paddle Dryer (Hosokawa Micron GmbH;

Leingarten; Germany), Hosokawa Bepex® Disc Dryer (Hosokawa Micron GmbH, Leingarten, Germany), Holo-Flite® dryers (Metso Minerals Industries Inc., Danville, USA), and Nara Paddle Dryer (NARA Machinery Europe; Frechen; Germany). Moreover, fluidized bed dryers can also be used.

The drying can take place in the mixer itself, by heating the jacket or blowing hot air. Also suitable is a downstream dryer, such as a Hörmann Dryer, a rotary kiln or a heated screw. Particularly advantageous is mixed and dried in a fluidized bed dryer.

Preferred drying temperatures are in the range 100 to 250 ° C, preferably 120 to 220 ° C, more preferably 130 to 210 ° C, most preferably 150 to 200 ° C. The preferred residence time at this temperature in the reaction mixer or dryer is preferably at least 10 minutes, more preferably at least 20 minutes, most preferably at least 30 minutes, and usually at most 60 minutes. In a preferred embodiment of the present invention, the water-absorbing polymer particles are cooled after the thermal drying. The cooling is preferably carried out in contact coolers, particularly preferably blade coolers, very particularly preferably disk coolers. Suitable coolers are, for example, Hosokawa Bepex® Horizontal Paddle Coolers (Hosokawa Micron GmbH, Leingarten, Germany), Hosokawa Bepex® Disc Coolers (Hosokawa Micron GmbH, Leingarten, Germany), Holo-Flite® coolers (Metso Minerals Industries, Inc., Danville, USA ) and Nara Paddle Cooler (NARA Machinery Europe, Frechen, Germany). Moreover, fluidized bed coolers can also be used.

In the cooler, the water-absorbing polymer particles to 20 to 150 ° C, preferably 30 to 120 ° C, more preferably 40 to 100 ° C, most preferably 50 to 80 ° C, cooled.

Subsequently, the surface-postcrosslinked polymer particles can be classified again, wherein too small and / or too large polymer particles are separated and recycled to the process.

The surface-postcrosslinked polymer particles can be coated or post-moistened for further improvement of the properties. The post-wetting is preferably carried out at 30 to 80 ° C, more preferably at 35 to 70 ° C, most preferably at 40 to 60 ° C. If the temperatures are too low, the water-absorbing polymer particles tend to clump together and at higher temperatures water is already noticeably evaporating. The amount of water used for the rewetting is preferably from 1 to 10 wt .-%, particularly preferably from 2 to 8 wt .-%, most preferably from 3 to 5 wt .-%. By rewetting the mechanical stability of the polymer particles is increased and their tendency to static charge reduced. Advantageously, the post-humidification is carried out in the cooler after the thermal drying.

Suitable coatings for improving the swelling rate and the permeability (SFC) are, for example, inorganic inert substances, such as water-insoluble metal salts, organic polymers, cationic polymers and di- or polyvalent metal cations. Suitable coatings for dust binding are, for example, polyols. Suitable coating tions against the unwanted caking tendency of the polymer particles are, for example, fumed silica, such as Aerosil® 200, and surfactants, such as Span® 20.

The water-absorbing polymer particles have a centrifuge retention capacity (CRC) of typically at least 15 g / g, preferably at least 20 g / g, preferably at least 22 g / g, more preferably at least 24 g / g, most preferably at least 26 g / g. The centrifuge retention capacity (CRC) of the water-absorbing polymer particles is usually less than 60 g / g. Centrifuge Retention Capacity (CRC) is determined according to the EDANA recommended Test Method No. WSP 241.2-05 "Fluid Retention Capacity in Saline, After Centrifugation".

The mixtures according to the invention preferably contain at least 80% by weight, preferably at least 85% by weight, particularly preferably at least 90% by weight, very particularly preferably at least 95% by weight, of water-absorbing polymer particles.

The irregular activated carbon particles have a surface area of preferably 10 to 10,000 m ² / g, more preferably 100 to 5,000 m ² / g, most preferably 1,000 to 2,000 m ² / g. The mean particle size of the irregular activated carbon particles is preferably at least 300 μm, particularly preferably from 350 to 550 μm, very particularly from 400 to 500 μm. The mean particle size of the product fraction can be determined by means of the EDANA recommended test method No. WSP 220.2-05 "Particle Size Distribution", in which the mass fractions of the sieve fractions are cumulatively applied and the average particle size is determined graphically. The mean particle size here is the value of the mesh size, which results for accumulated 50 wt .-%.

The proportion of irregular activated carbon particles having a particle size of 300 to 600 μm preferably amounts to at least 90% by weight, more preferably at least 95% by weight, very particularly preferably at least 98% by weight.

The mixtures according to the invention preferably contain at least 0.1% by weight, more preferably at least 0.5% by weight, preferably at least 1% by weight, very preferably at least 5% by weight, of irregular activated carbon particles.

The nature of the mixing is not limited and may already take place during the production of the water-absorbing polymer particles, for example during cooling after surface postcrosslinking or the subsequent classification, or in a special mixer. Suitable mixers have already been described above in the surface postcrosslinking of the water-absorbing polymer particles. The present invention is based on the finding that low-dust activated carbon particles have a higher abrasion resistance and are present in the mixtures according to the invention predominantly isolated in addition to the water-absorbing polymer particles. The formation of fine dust or coloring of the water-absorbing polymer particles by abrasion is avoided.

The odor-inhibiting mixtures may additionally contain metal peroxides, oxidases and / or zeolites. The metal peroxide is preferably the peroxide of a metal of FIG. Main group, the 2.

Main group and / or the 2nd subgroup of the Periodic Table of the Elements, particularly preferably the peroxide of a metal of the 2nd subgroup of the Periodic Table of the Elements.

Suitable metal peroxides are, for example, lithium peroxide, strontium peroxide, barium peroxide, sodium peroxide, magnesium peroxide, calcium peroxide and potassium peroxide, particularly preferably zinc peroxide.

The mixture according to the invention preferably contains from 0.001 to 5% by weight, preferably from 0.01 to 3% by weight, particularly preferably from 0.1 to 1.5% by weight, very particularly preferably from 0.2 to 0, 8 wt .-%, of the metal peroxide.

Metal peroxides, in particular zinc peroxide, have a good odor-inhibiting effect and the mixtures prepared therewith have a high storage stability. The mixtures preferably contain less than 1 ppm, more preferably less than 10 ppm, most preferably less than 5 ppm, heavy metal ions. Heavy metal ions, in particular iron ions, lead to the catalytic decomposition of the metal peroxides and thus reduce the storage stability of the mixtures. Suitable zeolites are, for example, zeolites with cations of the 1st main group, the 2nd main group, the 1st Subgroup and / or the 2nd subgroup of the Periodic Table of the Elements.

Suitable cations are, for example, zinc cations, silver cations and copper cations, particularly preferably titanium cations.

The mixture according to the invention preferably contains from 0.001 to 5% by weight, preferably from 0.01 to 3% by weight, particularly preferably from 0.1 to 1.5% by weight, very particularly preferably from 0.2 to 0, 8% by weight of the zeolite.

Zeolites also have a good odor-inhibiting effect. Suitable oxidases are oxidases of the group EC 1 .1 .3.x, such as glucose oxidases (EC number 1 .1 .3.4), the group EC 1 .3.3.x, such as bilirubin oxidases (EC number 1.3.3.5), the group EC 1 .4.3.x, such as glycine oxidases (EC number 1 .4.3.19), group EC 1 .5.3.x, such as polyaminoxides (EC number 1.5.3.1 1), group EC 1.6.3. x, such as NAD (P) H-oxidases (EC number 1 .6.3.1), group EC 1.7.3.x, such as hydroxylamine oxidases (EC number 1.7.3.4), group EC 1.8.3.x, such as sulfite oxidases (EC No. 1 .8.3.1), the group EC 1.9.3.x, such as cytochrome oxidases (EC number 1.9.3.1), the group EC 1 .10.3.x, such as catechol oxidases (EC number 1 .10.3.1), the group EC 1.16.3.x, such as ferroxidase (EC number 1.16.3.1), the group EC 1 .17.3.x, such as xanthine oxidases (EC number 1.17.3.2), and the group EC 1 .21 .3.z, such as reticulin oxidases (EC No. 1 .21.3.3).

Advantageously, a glucose oxidase (EC number 1.1.3.4) is used. It is even more advantageous if the glucose oxidase contains very little or no catalase (EC number 1.1 1 .1.6). The specific catalytic oxidase activity of the odor-inhibiting mixture is preferably from 0.01 to 1000 μηηοΙ substrate g ^_1 min ^-1 , more preferably from 0.1 to 100 μηηοΙ substrate g ^_1 -min ^-1 , most preferably from 1 to 10 μηηοΙ substrate g ^_1 min ^-1 .

The specific catalytic oxidase activity of the mixture can be determined by conventional methods. However, it is better to determine the catalytic activity of the oxidase itself and to calculate the specific catalytic oxidase activity of the mixture by calculation.

Oxidases can reduce unpleasant odors, especially unpleasant odors caused by sulfur compounds. This may be caused by hydrogen peroxide produced as a result of the catalytic oxidase activity. Therefore, the simultaneous use of peroxidases should be avoided.

The odor-inhibiting mixtures may additionally contain the substrate of the oxidase. A Substart is a compound that is converted by the enzyme in a chemical reaction. The first step in an enzymatic reaction is the formation of an enzyme-substrate complex, which after the reaction leads to the release of product and enzyme, so that the catalytic cycle can be run through again. An enzyme can possibly convert several different substrates, which are often chemically similar. Substrates in the context of the present invention are substrates of the oxidases which can be used according to the invention, for example β-D-glucose for glucose oxidase.

It is preferably from 0.5 to 25 wt .-%, particularly preferably from 5 to 20 wt .-%, most preferably from 8 to 15 wt .-% of the substrate used, each based on the water-absorbing polymer particles.

The substrates can also be used encapsulated, so that they are available only when adding liquid of the oxidase, for example by a coating with water-soluble polymers such as polyvinyl alcohol. However, it is also possible instead or in addition to encapsulate the oxidases to be used according to the invention.

A further subject of the present invention are hygiene articles containing a mixture according to the invention, in particular hygiene articles for light and severe incontinence.

The sanitary articles usually contain a water-impermeable back, a water-permeable upper side and in between an absorbent core of the water-absorbing polymer particles according to the invention and fibers, preferably cellulose. The proportion of the water-absorbing polymer particles according to the invention in the absorbent core is preferably from 20 to 100% by weight, preferably from 50 to 100% by weight.

Methods: Measurements should be taken at an ambient temperature of 23 ± 2 ° C and a relative humidity of 50 ± 10%, unless otherwise specified. The water-absorbing polymer particles are thoroughly mixed before the measurement.

CIE color number (L, a, b)

The color measurement is carried out according to the CIELAB method (Hunterlab, Volume 8, Volume 1996, Issue 7, Pages 1 to 4) with a colorimeter, model "LabScan XE S / N LX17309" (HunterLab, Reston, US) The colors are described by the coordinates L, a and b of a three-dimensional system, where L indicates the brightness, where L = 0 means black and L = 100 white The values for a and b indicate the position of the color on the color axes red / green or yellow / blue, where + a stands for red, -a for green, + b for yellow and -b for blue According to the formula HC60 = L-3b, the HC60 value is calculated.

The color measurement corresponds to the tristimulus method according to DIN 5033-6.

dust count

When determining the dust number, dusty fractions of solids which arise after defined stress of the material (free fall and impact) are quantitatively recorded.

The dust number of the water-absorbing polymer particles is determined with the aid of the dust measuring device type DustView (Palas GmbH, Karlsruhe, Germany).

The mechanical part of the measuring device consists of a filling funnel with flap, downpipe and dust housing with removable dust box. The downpipe has a length of 780 mm. The dust housing has a length of 195 mm, a width of 190 mm and a height of 185 mm. The sample amount is 30 g. For the measurement, the sample falls through the downpipe into the dust box.

The evaluation is done opto-electronically. The dusty solid content leads to the attenuation of a light beam, which is detected photometrically. The measurement is performed 130 mm above the bottom of the dust housing. Measured is the percentage weakening of the

Lichtstrrahls. A reading of 100 equals a complete weakening. The

Measurement value registration and evaluation takes place in the control unit. The following measured values are displayed as a numerical value on the control unit:

1 . Initial value (measured value after 0.5 seconds)

2. Dust value (reading after 30 seconds)

3. Dust number The dust number is the sum of initial value and dust value.

Examples Example 1 to 5

55 g of water-absorbing polymer particles (HySorb® B7055, BASF SE, DE) and 2.75 g of irregular charcoal particles were weighed into a 100 ml plastic square bottle. This mixture was homogenized for 15 minutes at 49 rpm in a tumble mixer and analyzed. The results are summarized in Table 1 (Sample A).

Then the 100ml plastic square bottle was emptied and not cleaned. Again, 55 g of water-absorbing polymer particles were weighed, but no activated carbon. This mixture was also homogenized for 15 minutes at 49 rpm in a tumble mixer and analyzed. The results are summarized in Table 1 (Sample B).

Tab. 1: Addition of different activated carbons to HySorb® B7055

^* ) not according to the invention

Examples 1 to 5 were carried out with Hysorb® B7055 (BASF SE, Ludwigshafen, Germany), commercially available surface-postcrosslinked water-absorbing polymer particles based on sodium acrylate with a degree of neutralization of 70 mol%. Such surface postcrosslinked water absorbing polymer particles are e.g. by BASF Aktiengesellschaft (trade name HySorb®), Stockhausen GmbH (trade name Favor®) and Nippon Shokubai Co., Ltd. (Trade name Aqualic®) commercially available.

The irregular activated carbon particles used in Examples 1 to 4 were Norit GCN3070 low-dust activated carbon (Norit Nederland BV, Amersfoort, the Netherlands), possibly mixed with active charcoal dust.

Activated carbon of the type Supelco 31616 (Sigma-Aldrich Chemie GmbH, Steinheim, Germany) was used as irregular activated carbon particles in Example 5.

Claims

claims

1 . Odor-inhibiting mixtures containing water-absorbing polymer particles and irregular charcoal particles having a dust number of less than 50.

2. Mixtures according to claim 1, characterized in that the mixtures contain at least 80 wt .-% water-absorbing polymer particles.

3. Mixtures according to claim 1 or 2, characterized in that the water-absorbing polymer particles have an average particle size of 250 to 600 μηη.

4. Mixtures according to one of claims 1 to 3, characterized in that the water-absorbing polymer particles to at least 90 wt .-% have a particle size of 150 to 850 μηη.

5. Mixtures according to one of claims 1 to 4, characterized in that the water-absorbing polymer particles have a Zentrifugeretenti- onskapazität of at least 15 g / g.

6. Mixtures according to one of claims 1 to 5, characterized in that the mixtures contain at least 1 wt .-% of irregular activated carbon particles.

7. Mixtures according to one of claims 1 to 6, characterized in that the irregular activated carbon particles have an average particle size of 350 to 550 μηη.

8. Mixtures according to one of claims 1 to 7, characterized in that the irregular activated carbon particles to at least 90 wt .-% have a particle size of 300 to 600 μηη.

9. Mixtures according to one of claims 1 to 8, characterized in that the irregular activated carbon particles have a surface area of 10 to 10,000 m ² / g.

10. Mixtures according to one of claims 1 to 9, characterized in that the mixtures additionally contain a metal peroxide.

1 1. Mixtures according to claim 10, characterized in that the metal peroxide is zinc peroxide.

12. Mixtures according to one of claims 1 to 1 1, characterized in that the mixtures additionally contain an oxidase.

13. Mixtures according to claim 12, characterized in that the oxidase is glucose seoxidase.

14. Mixtures according to claim 13, characterized in that the mixtures additionally contain glucose.

15. Hygiene article containing mixtures according to one of claims 1 to 14.