Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/42—Use of materials characterised by their function or physical properties
  • A61L15/425—Porous materials, e.g. foams or sponges
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/22—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing macromolecular materials
  • A61L15/26—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/42—Use of materials characterised by their function or physical properties
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/42—Use of materials characterised by their function or physical properties
  • A61L15/60—Liquid-swellable gel-forming materials, e.g. super-absorbents

Definitions

• the present invention relates to the use of water-absorbing polymer particles for absorption of blood and / or menstrual fluid, wherein the water-absorbing polymer particles are obtainable by polymerization of a foamed monomer solution or suspension, drying of the polymeric foam and grinding of the dried foam.
• Water-absorbent polymers are used as aqueous solution-absorbing products for the production of diapers, tampons, sanitary napkins, panty liners, wound dressings and other hygiene articles, but also as water-retaining agents in agricultural horticulture.
• Water-absorbing foams based on monomers containing crosslinked acid groups are known, for example from EP 0 858 478 B1, WO 97/31971 A1, WO 99/44648 A1 and WO 00/52087 A1. They are prepared, for example, by foaming a polymerizable aqueous mixture containing at least 50 mol% of neutralized, acid group-containing ethylenically unsaturated monomers, crosslinkers and at least one surfactant, and then polymerizing the foamed mixture.
• the foaming of the polymerizable mixture may be carried out by dispersing fine bubbles of a radical-inert gas or by dissolving such a gas under an increased pressure in the polymerizable mixture and depressurizing the mixture.
• the foams are used, for example, in hygiene articles for the acquisition, distribution and storage of body fluids.
• Water-absorbing polymer particles are commonly used in disposable diapers for the absorption of urine and optimized for this use. When absorbing aqueous suspensions, the water-absorbing polymer particles can indeed absorb the water contained in the aqueous suspension, but not the undissolved solids contained in the suspension. As a result, the surface of the water-absorbing polymer particles becomes coated with solid particles and the access of further water is prevented. There has therefore been no lack of attempts to optimize water-absorbing polymer particles for absorbing aqueous liquids from suspensions such as blood and menstrual fluid.
• WO 2005/042042 A1 teaches that water-absorbing polymer particles are coated with surfactants and alcohols to improve blood absorption.
• the object of the present invention was to provide hygiene articles with improved absorption of blood and menstrual fluid.
• the object is achieved by the use of water-absorbing polymer particles for absorption of blood and / or menstrual fluid, the water-absorbing polymer particles being polymerized by polymerization of a foamed aqueous monomer solution or suspension comprising a) at least one ethylenically unsaturated, acid group-carrying monomer which is from 25 to 95 molar % neutralized,
• drying of the polymeric foam and grinding of the dried foam are obtainable.
• 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.
• Suitable monomers a) are, for example, ethylenically unsaturated sulfonic acids, such as styrenesulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid (AMPS).
• sulfonic acids such as styrenesulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid (AMPS).
• AMPS 2-acrylamido-2-methylpropanesulfonic acid
• 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,
• the amount of monomer a) is preferably 20 to 90 wt .-%, particularly preferably 30 to 85 wt .-%, most preferably 35 to 75 wt .-%, each based on the unneutralized monomer a) and the monomer solution or -Suspension. Based on the unneutralized monomer a) in the context of this invention means that for the calculation of the proportion of the monomer a) is used prior to neutralization, ie the contribution of neutralization is disregarded.
• the acid groups of the monomers a) are neutralized to 25 to 95 mol%, preferably to 40 to 85 mol%, preferably to 50 to 80 mol%, particularly preferably to 55 to 75 mol%, using the usual neutralizing agents can be, for example, alkali metal hydroxides, alkali metal oxides, alkali metal carbonates or alkali metal hydrogencarbonates and mixtures thereof.
• the neutralization can also be carried out with ammonia, amines or alkanolamines, such as ethanolamine, diethanolamine or triethanolamine.
• an inorganic base preferably potassium carbonate, sodium carbonate or Sodium hydroxide
• the proportion of acrylic acid and / or salts thereof in the total amount of monomers a) is preferably at least 50 mol%, particularly preferably at least 90 mol%, very particularly preferably at least 95 mol%.
• the monomers a) usually contain polymerization inhibitors, preferably hydroquinone half ethers, as storage stabilizer.
• the monomer solution preferably contains up to 250 ppm by weight, preferably at most
• hydroquinone in each case based on the unneutralized monomer a).
• an ethylenically unsaturated, acid group-carrying monomer having a corresponding content of hydroquinone half-ether can be used to prepare the monomer solution.
• 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 are incorporated in the Polymer chain can be radically copolymerized, and functional groups that can form covalent bonds with the acid groups of the monomer a). Furthermore, polyvalent metal salts which can form coordinative bonds with at least two acid groups of the monomer a) 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
• Preferred crosslinkers b) are pentaerythritol triallyl ether, tetraalloxyethane, methylenebismethacrylamide, tetraallyammonium chloride, 15-times 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.
• 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 1 to 10 wt .-%, more preferably 2 to 7 wt .-%, most preferably 3 to 5 wt .-%, each based on the unneutralized monomer a).
• the centrifuge retention capacity (CRC) decreases and the absorbance under a pressure of 21.0 g / cm 2 (AUL 0.3 psi) goes through a maximum.
• initiators c) it is possible to use all compounds which generate radicals under the polymerization conditions, for example thermal initiators, redox initiators, photoinitiators.
• Thermal initiators are, for example, peroxides, hydroperoxides, hydrogen peroxide, persulfates and azo initiators.
• Suitable azo initiators are, for example, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis (N, N-dimethylene) isobutyramidine dihydrochloride, 2- (Carbamoylazo) isobutyronitrile, 2,2'-azobis [2- (2'-imidazolin-2-yl) propane] dihydrochloricl and 4,4'-azobis (4-cyanovaleric acid).
• Photoinitiators are, for example, ⁇ -splitters, H-abstracting systems and azides.
• Suitable ⁇ -splitters or H-abstracting systems are, for example, benzophenone derivatives, such as Michler's ketone, phenanthrene derivatives, fluorene derivatives, anthraquinone derivatives, thioxanthone derivatives, coumarin derivatives, benzoin ethers and their derivatives, azo starters, such as the radical generators mentioned above, substituted hexaarylbisimidazoles or acylphosphine oxides.
• Suitable azides are, for example, 2- (N, N-dimethylamino) ethyl-4-azidocinnamate, 2- (N, N-dimethylamino) ethyl-4-azidonaphthyl ketone, 2- (N, N-dimethylamino) ethyl 4-azidobenzoate, 5-azido-1-naphthyl-2 '- (N, N-dimethylamino) ethylsulfone, N- (4-sulfonylazidophenyl) maleimide, N-acetyl-4-sulfonylazidoaniline, 4-sulfonylazidoaniline, 4-azidoaniline, 4 -Azidophenacylbromid, p-azido benzoic acid, 2,6-bis (p-azidobenzylidene) cyclohexanone and 2,6-bis (p
• the initiators c) are used in conventional amounts, preferably at least 0.01 mol%, particularly preferably at least 0.05 mol%, very particularly preferably at least 1 mol%, and usually less than 5 mol%, preferably less than 2 mol%, based on the monomers a).
• the surfactants d) are of crucial importance for the preparation and stabilization of the foamed monomer solution or suspension.
• Useful nonionic surfactants are, for example, addition products of alkylene oxides, in particular ethylene oxide, propylene oxide and / or butylene oxide with alcohols, amines, phenols, naphthols or carboxylic acids.
• addition products of ethylene oxide and / or propylene oxide to at least 10 carbon atoms containing alcohols the addition products per mole of alcohol 3 to 200 moles of ethylene oxide and / or propylene oxide attached.
• the addition products contain the alkylene oxide units in the form of blocks or in random distribution.
• nonionic surfactants which can be used are the addition products of 7 mol of ethylene oxide and 1 mol of tallow fatty alcohol, reaction products of 9 mol of ethylene oxide with 1 mol of tallow fatty alcohol and addition products of 80 mol of ethylene oxide and 1 mol of tallow fatty alcohol.
• Other useful commercial nonionic surfactants consist of reaction products of oxo alcohols or Ziegler alcohols with 5 to 12 moles of ethylene oxide per mole of alcohol, especially with 7 moles of ethylene oxide.
• Other useful commercial nonionic surfactants are obtained by ethoxylation of castor oil. For example, 12 to 80 moles of ethylene oxide are added per mole of castor oil.
• Further commercial products which can be used are, for example, the reaction products of 18 mol of ethylene oxide with 1 mol of tallow fatty alcohol, the addition products of 10 mol of ethylene oxide with 1 mol of a Ci3 / Ci5-oxoalcohol, or the reaction products of 7 to 8 mol of ethylene oxide with 1 mol of a Ci3 / Ci5 oxo alcohol.
• WEI Other suitable nonionic surfactants are phenol alkoxylates, such as p-tert-butylphenol, which is reacted with 9 moles of ethylene oxide, or methyl ethers of reaction products of 1 mole of a C12 to Cis alcohol and 7.5 moles of ethylene oxide.
• the nonionic surfactants described above can be converted, for example, by esterification with sulfuric acid into the corresponding sulfuric acid half esters.
• the sulfuric acid half esters are used in the form of the alkali metal or ammonium salts as anionic surfactants.
• Suitable anionic surfactants are, for example, alkali metal or ammonium salts of sulfuric monoesters of addition products of ethylene oxide and / or propylene oxide with fatty alcohols, alkali metal or ammonium salts of alkylbenzenesulfonic acid or of alkylphenol ether sulfates. Products of the type mentioned are commercially available.
• the sodium salt of a sulfuric monoester of a Ci3 / Ci5-oxoalcohol reacted with 106 moles of ethylene oxide, the triethanolamine salt of dodecylbenzenesulfonic acid, the sodium salt of alkylphenol ether sulfates and the sodium salt of the sulfuric acid half ester of a reaction product of 106 moles of ethylene oxide with 1 mole of tallow fatty alcohol are commercially available anionic surfactants.
• anionic surfactants are sulfuric monoesters of C 13 / C 15 -oxo alcohols, paraffin sulfonic acids, such as cis-alkyl sulfonate, alkyl-substituted benzenesulfonic acids and alkyl-substituted naphthalenesulfonic acids such as dodecylbenzenesulfonic acid and di-n-butylnaphthalenesulfonic acid, and also fatty alcohol phosphates, such as C 5 / C 18 -fatty alcohol phosphate.
• the polymerizable aqueous mixture may contain combinations of a nonionic surfactant and an anionic surfactant or combinations of nonionic surfactants or combinations of anionic surfactants.
• cationic surfactants are suitable. Examples of these are the dimethyl sulfate-quaternized reaction products of 6.5 mol of ethylene oxide with 1 mol of oleylamine, distearyldimethylammonium chloride, lauryltrimethylammonium chloride, cetylpyridinium bromide and dimethyl sulfate-quaternized stearic acid-triethanolamine ester, which is preferably used as cationic surfactant.
• the surfactant content, based on the unneutralized monomer a) is preferably 0.01 to 10 wt .-%, more preferably 0.1 to 5 wt .-%, most preferably 0.5 to
• acrylamide, methacrylamide, hydroxyethyl acrylate, hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminopropyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate are ethylenically unsaturated monomers e) which are copolymerizable with the ethylenically unsaturated acid group-carrying monomers a).
• Solubilizers f) are water-miscible organic solvents, for example dimethylsulfoxide, dimethylformamide, N-methylpyrrolidone, monohydric alcohols, glycols, polyethylene glycols or monoethers derived therefrom, the monoethers containing no double bonds in the molecule.
• Suitable ethers are methyl glycol, butyl glycol, butyl diglycol, methyl diglycol, butyl triglycol, 3-ethoxy-1-propanol and glycerol monomethyl ether. If solubilizers f) are used, their content in the monomer solution or suspension is preferably up to 50% by weight, particularly preferably 1 to 25% by weight, very particularly preferably 5 to 10% by weight.
• the monomer solution or suspension may contain thickeners, foam stabilizers, fillers, fibers and / or cell nucleating agents g).
• Thickeners are used, for example, to optimize the foam structure and to improve foam stability. This ensures that the foam shrinks only slightly during the polymerization.
• Suitable thickeners are all known natural and synthetic polymers which greatly increase the viscosity of an aqueous system and do not react with the amino groups of the basic polymers. These may be water-swellable or water-soluble synthetic and natural polymers.
• suitable thickener water-swellable or water-soluble synthetic polymers are high molecular weight polyethylene glycols or copolymers
• Ethylene glycol and propylene glycol and high molecular weight polysaccharides such as starch, guar gum, locust bean gum or derivatives of natural substances, such as carboxymethylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, hydroxypropylcellulose and cellulose mixed ether.
• Another group of thickeners are water-insoluble products, such as finely divided silica, zeolites, bentonite, cellulose powder or other finely divided powders of crosslinked polymers.
• the monomer solution or suspension may contain the thickeners in amounts of up to 30% by weight. If such thickening agents are used at all, they are contained in amounts of from 0.1 to 10% by weight, preferably 0.5 to 20% by weight, in the monomer solution or suspension.
• hydrocarbons having at least 5 C atoms in the molecule are, for example, pentane, cyclopentane, hexane, cyclohexane, heptane, octane, isooctane, decane and dodecane.
• the aliphatic hydrocarbons contemplated may be straight chain, branched or cyclic and have a boiling temperature which is above the temperature of the aqueous mixture during foaming. The aliphatic hydrocarbons increase the service life of the not yet polymerized foamed aqueous reaction mixture.
• the hydrocarbons act as cell nucleating agents and at the same time stabilize the already formed foam. In addition, they can cause further foaming when polymerizing the monomer solution or suspension. You can then also have the function of a propellant.
• chlorinated or fluorinated hydrocarbons Use hydrogen sulfide as a cell nucleating agent and / or foam stabilizer, such as dichloromethane, trichloromethane, 1, 2-dichloroethane, trichlorofluoromethane or 1, 1, 2-trichlorotrifluoroethane. If hydrocarbons are used, they are used, for example, in amounts of from 0.1 to 20% by weight, preferably from 0.1 to 10% by weight, based on the monomer solution or suspension.
• one or more fillers may be added, for example, chalk, talc, clay, titanium dioxide, magnesium oxide, alumina, precipitated silicas in hydrophilic or hydrophobic modifications, dolomite and / or calcium sulfate be contained in the monomer solution or suspension in amounts up to 30 wt .-%.
• the aqueous monomer solutions or suspensions described above are first foamed.
• an inert gas such as nitrogen, carbon dioxide or air
• an inert gas can be dissolved in the aqueous monomer solution or suspension under a pressure of, for example, 2 to 400 bar and then allowed to relax to atmospheric pressure.
• When relaxing from at least one nozzle creates a flowable monomer foam. Since gas sensitivity increases with decreasing temperature, gas saturation and subsequent foaming should be carried out at the lowest possible temperature, avoiding unwanted precipitation. It is also possible to foam the aqueous monomer solutions or suspensions by another method by dispersing therein fine bubbles of an inert gas.
• the foaming of the aqueous monomer solutions or suspensions can be carried out in the laboratory, for example, by foaming the aqueous monomer solution or suspension in a food processor equipped with a whisk. Furthermore, it is possible to foam the aqueous monomer solutions or suspensions with carbon dioxide by using carbonates or bicarbonates for the neutralization.
• the generation of foam is preferably carried out in an inert gas atmosphere and with inert gases, for example by addition of nitrogen or noble gases under normal pressure or elevated pressure, for example up to 25 bar and subsequent expansion.
• inert gases for example by addition of nitrogen or noble gases under normal pressure or elevated pressure, for example up to 25 bar and subsequent expansion.
• the consistency of the monomer foams, the size of the gas bubbles and the distribution of the gas bubbles in the monomer foam can be varied within a wide range, for example by selecting the surfactants d), solubilizers f), foam stabilizers, cell nucleating agents, thickeners and fillers g). This allows you to easily adjust the density, the degree of Offsenmaschine and the wall thickness of the monomer foam.
• the aqueous monomer solution or suspension is preferably foamed at temperatures below the boiling point of its constituents, for example at ambient temperature up to 100 ° C, preferably at 0 to 50 ° C, more preferably at 5 to 20 ° C.
• temperatures below the boiling point of the component with the lowest boiling point by foaming the aqueous monomer solution or suspension in a container sealed in a pressure-tight manner. This gives monomer foams which are flowable and over a longer period of time are stable.
• the density of the monomer foams at a temperature of 20 ° C, for example, 0.01 to 0.9 g / cm 3 .
• the obtained monomer foam can be polymerized on a suitable support.
• the polymerization is carried out in the presence of customary radical-forming initiators c).
• the radicals can be generated for example by heating (thermal polymerization) or by irradiation with light of a suitable wavelength (UV polymerization).
• Polymeric foams having a layer thickness of up to about 5 millimeters are produced, for example, by one-sided or two-sided heating or, in particular, by irradiation of the monomer foams on one or both sides. If thicker polymeric foams are to be produced, for example polymeric foams with thicknesses of several centimeters, the heating of the monomer foam with the aid of microwaves is particularly advantageous because in this way a relatively uniform heating can be achieved. As the layer thickness increases, however, the proportion of unreacted monomer a) and crosslinker b) in the resulting polymeric foam increases.
• the thermal polymerization is carried out, for example, at temperatures of 20 to 80 ° C, preferably in the range of 40 ° C to 160 ° C, in particular at temperatures of 65 to 140 ° C.
• the monomer foam can be heated on both sides and / or irradiated, for example by means of contact heating or by irradiation or in a drying cabinet.
• Foams are open-celled.
• the proportion of open cells is for example at least 80%, preferably it is above 90%.
• Particularly preferred are polymeric foams having an open cell content of 100%.
• the proportion of open cells in the polymeric foam is determined, for example, by means of scanning electron microscopy (Scanning Electron Microscopy).
• drying of the polymeric foam takes place. This removes water and other volatile components.
• suitable drying methods are thermal convection drying, such as forced-air drying, thermal contact drying, such as drum drying, radiation drying, such as infrared drying, dielectric drying, such as microwave drying, and freeze-drying.
• the drying temperatures are usually in the range 50 to 250 ° C, preferably 70 to 200 ° C, more preferably 90 to 170 ° C, most preferably 100 to 150 ° C.
• the preferred residence time at this temperature in the dryer is preferably 1 to 60 minutes, more preferably 2 to 30 minutes, most preferably 5 to 15 minutes.
• the product temperature is 120 ° C, preferably 100 ° C, not exceeding.
• a particularly suitable drying process is the (vacuum) belt drying.
• the polymeric foam usually contains less than 10% by weight of water.
• the water content of the polymeric foam can be arbitrarily adjusted by wetting with water or steam.
• the dried polymeric foam is thereafter ground and classified, wherein for grinding usually one- or multi-stage roller mills, pin mills, hammer mills or vibratory mills can be used.
• the dried polymeric foam is pre-ground by means of a granulator and subsequently remilled by means of a baffle plate mill.
• Milling a pre-dried polymeric foam results in less undesirably small polymer particles.
• the water-absorbing polymer particles are sieved using appropriate sieves to a particle size in the range of preferably 100 to 1 .mu.m, more preferably 150 to 850 .mu.m, very particularly preferably from 150 to 600 .mu.m.
• the average particle size of the polymer particles separated off as product fraction is preferably at least 200 ⁇ m, particularly preferably from 250 to 600 ⁇ m, very particularly from 300 to 500 ⁇ m.
• 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", wherein the mass fractions of the sieve fractions are cumulatively applied and the average particle size is determined graphically.
• the average particle size here is the value of the mesh width which results for a cumulative 50% by weight.
• the proportion of particles having a particle size of at least 150 ⁇ m is preferably at least 90% by weight, more preferably at least 95% by weight, very particularly preferably at least 98% by weight.
• the proportion of particles having a particle size of at most 850 ⁇ m 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 at most 710 ⁇ m 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 at most 600 ⁇ m is preferably at least 90% by weight, more preferably at least 95% by weight, most preferably at least 98% by weight.
• Polymer particles with too large particle size are less mechanically stable. 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 described in DE 33 14 019 A1, DE 35 23 617 A1 and EP 0 450 922 A2, or ⁇ -hydroxyalkylamides, as described in DE 102 04 938 A1 and US Pat. No. 6,239,230.
• 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-hydroxyethyloxazolidin-2-one, oxazolidin-2-one and 1, 3-propanediol.
• 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.
• polyvalent cations are applied to the particle surface in addition to the surface postcrosslinkers before, during or after the surface postcrosslinking.
• the polyvalent cations which can be used 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 the cations of titanium and zirconium.
• 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 the cations of titanium and zirconium.
• chloride, bromide, sulfate, hydrogensulfate, carbonate, hydrogencarbonate, nitrate, phosphate, hydrogenphosphate, dihydrogenphosphate and carboxylate, such as acetate and lactate are possible.
• Aluminum sulfate is preferred.
• polyamines can also be used
• the surface postcrosslinking is usually carried out so that a solution of the surface postcrosslinker is sprayed onto the dried polymer particles. Following the spraying, the surface postcrosslinker coated polymer particles are thermally dried, whereby the surface postcrosslinking reaction can occur both before and during drying.
• the spraying of a solution of the surface postcrosslinker is preferably carried out in mixers with agitated mixing tools, such as screw mixers, disc mixers and paddle mixers.
• Particularly preferred are horizontal mixers, such as paddle mixers, very particularly preferred are vertical mixers.
• horizontal mixer and vertical mixer via the storage of the mixing shaft ie horizontal mixer have a horizontally mounted mixing shaft and vertical mixer have a vertically mounted mixing shaft.
• Suitable mixers are, for example, Horizontal Pflugschar® mixers (Gebr. Lödige Maschinenbau GmbH, Paderborn, DE), Vrieco-Nauta Continuous Mixers (Hosokawa Micron BV, Doetinchem, NL), Processall Mixmill Mixers (Processall Incorporated, Cincinnati, US) and Schugi Flexomix® (Hosokawa Micron BV, Doetinchem, NL).
• the surface postcrosslinkers are typically used as an aqueous solution. The penetration depth of the surface postcrosslinker into the polymer particles can be adjusted by the content of nonaqueous solvent or total solvent amount.
• solvent 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 include, for example, Hosokawa Bepex® Horizontal Paddle Dryer (Hosokawa Micron GmbH, Leingart, DE), Hosokawa Bepex® Disc Dryer (Hosokawa Micron GmbH, Leingart, DE), and Nara Paddle Dryer (NARA Machinery Europe, Frechen, DE).
• fluidized bed dryers can also be used.
• the drying can take place in the mixer itself, by heating the jacket or blowing hot air.
• a downstream dryer such as a Horde 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 10 to 120 minutes, more preferably 20 to 90 minutes, most preferably 30 to 60 minutes.
• the surface-postcrosslinked polymer particles can be classified again.
• the surface postcrosslinking is already carried out at the stage of the polymeric foam, with the amounts and temperatures for the polymer foam mentioned for the polymer particles correspondingly being applicable.
• the polymer particles can be coated or rehydrated to improve 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 polymer particles tend to clump together and at higher temperatures, water is already noticeably evaporating.
• the amount of water used for the rehydration is preferably from 1 to 10 wt .-%, particularly preferably from 2 to 8 wt .-%, most preferably from 3 to 5 wt .-%. Remoistening increases the mechanical stability and reduces the tendency to static charge.
• Suitable coatings for improving the swelling rate (FSR) and the liquid transfer (SFC) are, for example, inorganic inert substances, such as water-insoluble metal salts, organic polymers, cationic polymers and di- or polyvalent metal cations, such as aluminum sulfate and aluminum lactate.
• Suitable coatings for dust binding are, for example, polyols.
• Suitable coatings against the unwanted tendency of the polymer particles to cake are, for example, fumed silica, such as AeroSil® 200, and surfactants, such as Span® 20.
• Suitable coatings for reducing the content of unreacted monomers are, for example, reducing agents, such as the salts of the sulfurous ones Acid, hypophosphorous acid and / or organic sulphonic acid.
• reducing agents such as the salts of the sulfurous ones Acid, hypophosphorous acid and / or organic sulphonic acid.
• reducing agent but preferably a mixture of the sodium salt of 2-hydroxy-2-sulfinatoacetic acid, the disodium salt of 2-hydroxy-2-sulfonatoacetic acid and sodium hydrogen sulfite used.
• Such mixtures are available as Brüggolite® FF6 and Brüggolite® FF7 (Brüggemann Chemicals, Heilbronn, DE).
• the post-wetting and / or the coating is already carried out at the stage of the polymeric foam.
• the water-absorbing polymer particles have a moisture content of preferably 0 to 15 wt .-%, more preferably 0.2 to 10 wt .-%, most preferably 0.5 to 8 wt .-%, wherein the water content in accordance with the EDANA recommended test method No. WSP 230.2-05 "Moisture content" is determined.
• the water-absorbing polymer particles have a centrifuge retention capacity (CRC) of typically at least 10 g / g, preferably at least 15 g / g, preferably at least 20 g / g, more preferably at least 22 g / g, most preferably at least 25 g / g.
• the centrifuge retention capacity (CRC) of the water-absorbing polymer particles is usually less than 40 g / g.
• the centrifuge retention capacity (CRC) is determined according to the EDANA recommended test method no. WSP 241.2-05 "Centrifuge retention capacity".
• the water-absorbing polymer particles have a blood absorption of typically at least 8 g / g, preferably at least 12 g / g, preferably at least 15 g / g, more preferably at least 18 g / g, most preferably at least 20 g / g.
• the blood absorption of the water-absorbing polymer particles is usually less than 30 g / g.
• the water-absorbing polymer particles have an absorption under a pressure of 49.2 g / cm 2 (AUL0.7 psi) of typically at least 10 g / g, preferably at least
• the absorption under a pressure of 49.2 g / cm 2 (AUL0.7 psi) of the water-absorbent polymer particles is usually less than 30 g / g.
• the absorption under a pressure of 49.2 g / cm 2 (AUL0.7 psi) is determined analogously to the EDANA recommended test method no. WSP 242.2-05 "absorption under pressure", whereby instead of a pressure of 21, 0 g / cm 2 a pressure of 49.2 g / cm 2 is set.
• the water-absorbing polymer particles to be used according to the invention have a high absorption capacity for blood and a high swelling rate and are therefore particularly suitable for use in hygiene articles for absorbing blood and menstrual fluid.
• 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.
• the blood absorption is determined according to the EDANA recommended test method no. WSP 241.2-05 "Centrifuge Retention Capacity", wherein instead of a 0.9 wt .-% aqueous sodium chloride solution according to US 6,147,424 (column 17, line 33 to column 18, Line 45) modified sheep blood is used.
• FSR source velocity
• the monomer foam obtained was applied to a DIN A3-sized glass plate with 3 mm high edges and covered with a second glass plate.
• the foam sample was irradiated synchronously from both sides for 4 minutes with UV light, from the top with a UVA / IS emitter UVASPOT 1000 / T (Dr Hönle AG, Gräfelfing, DE), from below with 2 UVA / IS emitters UVASPOT 400 / T (Dr. Hönle AG, Gräfelfing, DE).
• the foam layer obtained was completely dried in a convection oven at 100 ° C, then ground in a Retschmühle and sieved to a particle size of 150 to 600 ⁇ .
• Solids content of the reaction mixture 40.6% by weight
• the obtained water-absorbent polymer particles had a blood absorption of 17.9 g / g and a swelling rate of 2.0 g / gs.
• Example 2 comparative example
• Example 2 The procedure was as in Example 1. The monomer solution was not foamed. The obtained water-absorbent polymer particles had a blood absorption of 14.6 g / g and a swelling rate of 0.17 g / gs.
• the resulting homogeneous solution was transferred to a pressure vessel and saturated there with carbon dioxide for 25 minutes at a pressure of 12 bar and a flow of 300 l / h. Under pressure, 6.67 g of a 3% strength by weight aqueous solution of Wako® V-50 (2,2'-azobis (2-amidinopropane) dihydrochloride) was added and mixed in with a strong stream of carbon dioxide. Carbon dioxide was then passed through the reaction mixture for a further 5 minutes. The saturated with carbon dioxide reaction mixture was then pressed out at a pressure of 12 bar through a nozzle with a diameter of 1, 0 mm, forming a fine-celled, good flowable foam.
• the bottom of a DIN A3 glass plate with 3 mm high edges was covered with a transparent polyester film.
• the obtained monomer foam was applied to the glass plate and covered with a second transparent polyester film and a second glass plate.
• the foam sample was irradiated synchronously from both sides for 4 minutes with UV light, from the top with a UV / VIS irradiation UVASPOT 1000 / T (Dr. Hönle AG, Gräfelfing, DE), from below with 2 UV / VIS UVASPOT spotlights 400 / T (Dr. Hönle AG, Gräfelfing, DE).
• the resulting polymeric foam was sprayed with 5% by weight aqueous sodium metabisulfite so that it subsequently contained 3% by weight of sodium metabisulfite based on anhydrous polymer.
• the product was then dried for 30 minutes in a convection oven at 100 ° C, then ground in a Retschmühle and sieved to a particle size of 150 to 850 ⁇ .
• the obtained water-absorbent polymer particles had a blood absorption of 16.0 g / g and a swelling rate of 2.4 g / gs.

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• 2012
  • 2012-05-14 CN CN201280023834.3A patent/CN103596599B/zh not_active Expired - Fee Related
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