CA2179775C - Cross-linked polymers with a porous structure - Google Patents
Cross-linked polymers with a porous structure Download PDFInfo
- Publication number
- CA2179775C CA2179775C CA002179775A CA2179775A CA2179775C CA 2179775 C CA2179775 C CA 2179775C CA 002179775 A CA002179775 A CA 002179775A CA 2179775 A CA2179775 A CA 2179775A CA 2179775 C CA2179775 C CA 2179775C
- Authority
- CA
- Canada
- Prior art keywords
- water
- cross
- polymers according
- linked
- swellable
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
- C09B67/00—Influencing the physical, e.g. the dyeing or printing properties of dyestuffs without chemical reactions, e.g. by treating with solvents grinding or grinding assistants, coating of pigments or dyes; Process features in the making of dyestuff preparations; Dyestuff preparations of a special physical nature, e.g. tablets, films
- C09B67/0097—Dye preparations of special physical nature; Tablets, films, extrusion, microcapsules, sheets, pads, bags with dyes
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
- C05G5/00—Fertilisers characterised by their form
- C05G5/40—Fertilisers incorporated into a matrix
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/04—Acids; Metal salts or ammonium salts thereof
- C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/52—Amides or imides
- C08F220/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
- C08F220/56—Acrylamide; Methacrylamide
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F251/00—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F261/00—Macromolecular compounds obtained by polymerising monomers on to polymers of oxygen-containing monomers as defined in group C08F16/00
- C08F261/02—Macromolecular compounds obtained by polymerising monomers on to polymers of oxygen-containing monomers as defined in group C08F16/00 on to polymers of unsaturated alcohols
- C08F261/04—Macromolecular compounds obtained by polymerising monomers on to polymers of oxygen-containing monomers as defined in group C08F16/00 on to polymers of unsaturated alcohols on to polymers of vinyl alcohol
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F8/00—Chemical modification by after-treatment
Abstract
The invention relates to cross-linked synthetic polymers based on acrylic acid and its derivatives with a high absorbency and improved absorbency rate for water, aqueous solutions and bodily fluids, a process for their production by radical polymerisation in conditions leading to polymers having a porous structure and a particle density depending on the degree of swelling so that the polymer particles can float in water or aqueous fluids and the use of these polymers for the absorption and/or retention of water and the transfer of water and/or an active agent solution to a surrounding medium. The porous structure of the polymer is formed by nitrogen dispersed in it. At least one azo compound with a half exchange time of at least 10 hours at a temperature of 30 to 120 °C is added to the aqueous monomer solution as a polymerisation initiator and foaming agent.
Description
The present invention relates to cross-linked synthetic polymers based on acrylic acid and its derivatives, which have a high ab-sorption capacity and an improved absorption rate for water, aqueous solutions and body fluids. The present invention further relates to a process for their preparation by means of radical po-lymerization under conditions that result in polymers having a po-rous structure and a particle density which depends on the swel-ling degree so that the polymer particles are floatable in water or aqueous liquids. The present invention further relates to the use of these polymers for the absorption and/or retention of water and for the release of water or aqueous solutions and/or an active substance solution to a surrounding medium.
Various patents describe different synthetic polymers having an absorbing capacity for water and body fluids, e.g., cross-linked polymers and copolymers based on acrylic or methacrylic acid (U.S. 4 018 951; U.S. 4 066 583; U.S. 4 062 817; U.S. 4 066 583; DE-OS 26 13 135; DE-OS 27 12 043; DE-OS 28 13 634) or acrylamidopropane sulfonic acid copolymers (DE-PS 31 24 008).
These absorbents are virtually insoluble in water and absorb in equilibrium with aqueous liquids several times their own weight of water, urine, or other aqueous solutions. Some patents also de-scribe other properties of the synthetic absorbents in addition to the high liquid absorption capacity, e.g., low residual monomer content, low portion of water-soluble moieties, and high gel strength of the swollen polymer particles.
U.S. 4 529 739 and U.S. 4 649 164 describe polymers which have a porous structure and are based on methacrylic acid. They are obtained from ethyl acrylate/methacrylic acid copolymer latices under addition of compounds capable of separating carbon diox-ide, e.g., sodium hydrogencarbonate. Austrian patent AT 391 321 B describes cross-linked, porous acrylic polymers which are pro-duced by adding a nitrogen-containing blowing agent to the monomer solution. According to this method an N-containing blowing agent decomposing to ammonia and carbon dioxide at 80 to 250°C is added to acrylic acid, either before or after the po-lymerization. The acrylic acid is neutralized to the extent of 60 -100% with NaOH, KOH or NH3 , and the added quantity of N-containing blowing agent corresponds to an increase in the neu-tralization degree to 102 to 140%. Ammonium salts of inorganic or organic acids and urea are mentioned as blowing agents, am-monium carbonate being preferred. U.S. 5 118 719 also describes ammonium and alkali carbonates used as blowing agents which are added to the monomer solution prior to polymerization. Owing to the carbonate decomposition during polymerization, carbon di-oxide is formed and causes the formation of a "microcellular struc-ture" in the hydrogel. This may explain the improved absorption rate for liquids of the final product.
The use of alkali or ammonium carbonates prior to or during the polymerization of organic acids according to U.S. 4 529 739, U.S.
4 649 164, U.S. 5 1 18 719 results in the formation of carbon di-oxide during the neutralization of the monomer solution. Since C02 has a limited solubility in the monomer solution and in the polymer gel mass, only relatively small amounts of C02 can be incorporated into the polymer during polymerization or drying. Also, the alter-native according to AT 391 321 B, i.e., to add the blowing agent to the polymer gel prior to drying, does not result in the desired effect because of the superficial action of the aftertreatment. This method has the disadvantage that the added water amount must be removed during drying. Also, an excessive use of ammonia does not result in highly porous structures in swollen gel condi-tion, since ammonia is readily soluble in water or aqueous liquids.
Thus it is dissolved during swelling and the porosity of the hydro-gel particles substantially disappears. Moreover, the addition of ammonia and carbonate increases the pH of the final product to far beyond 7, and this greatly restricts the applicability of the products.
Starting from a water-soluble polymer based on acrylic acid, WO
88/09801 describes the production of a cross-linked, foamed ethyl acrylate/acrylic acid copolymer having a specific density of 0.20 g/cm3. The final product is manufactured in aqueous solution, and a subsequent cross-linkage and foaming operation under the addi-tion of a cross-linker and a blowing agent, e.g., sodium hydrogen-carbonate, p-toluenesulfonyl hydrazine or azo carboamide, is con-ducted in one process step. The drawback of this method is the fact that working in an aqueous solution is necessary and that the concentration is limited, e.g., to 18%-wt., because of the high viscosity in order to improve handling of the copolymer. Addi-tionally, large amounts of blowing agent, e.g., 27%-wt., relative to the copolymer, are required.
As is known from AT 391 321 B very small amounts of azo com-pounds, e.g., 0.056%-wt., relative to the monomer, are normally used as polymerization initiators. In case of higher concentrations of such radical formers, the excess of free radicals will result in polymers having a lower molecular weight and in products having insufficient absorbing properties.
Another feature of the known polymers capable of absorbing wa-ter or aqueous liquids is the fact that they cannot float on the liquid surface when placed into water or aqueous liquids in unswollen condition and after liquid absorption, unless they com-prise auxiliary agents, such as cork flour, as described in EP 0 285 404 B 1.
Accordingly, there was the object to avoid the above-mentioned drawbacks and to obtain absorbents having a porous structure, good absorption properties, in particular an improved absorption rate, and a low average total density of the individual particles, so that the polymer particles, particularly in swollen state, are able to float on the water surface.
Most surprisingly, it was found that water-swellable, cross-linked, particulate polymers having a porous structure and a high absorp-tion rate for water and aqueous liquids and a density of below 1 .0 g/cm3 in swollen condition and a density of above 1.0 g/cm3 in dry condition can be produced in higher concentrations by means of radical polymerization in aqueous solution by using at least one azo compound simultaneously as polymerization initiator and blowing agent. Suitable azo compounds are those having a half-time of 10 hours or more at a temperature ranging from 30 to 120°C, preferably in the temperature range of 60 to 120°C. The azo compounds are added to the monomer solution prior to po-lymerization. For preference, the following azo compounds are used:
1. Azonitrile-compounds:
2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropyl propionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1-azobis(cylcohexane-1-carbonitrile), AMENDED SHEET
1-[( 1-cyano-1-methyl ethyl)azo]formamide (2-(carbamoyl azo)isobutyronitrile, and 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile.
2. Azoamidine-compounds:
2,2'-azobis(2-methyl-N-phenylpropionamidine) dihydrochloride, 2,2'-azobis[N-(4-chlorophenyl)-2-methylpropionamidine] dihydro-chloride, 2,2'-azobis(N-(4-hydroxyphenyl)-2-methylpropionamidine] dihydro-chloride, 2,2'-azobis[N-(4-aminophenyl)- 2-methylpropionamidine] tetrahy-drochloride, 2,2'-azobis(2-methyl-N-(phenylmethyl)-propionamidine] dihydro-chloride, 2,2'-azobis[2-methyl-N-2-propenyl propionamidine] dihydrochlo-ride, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, and 2,2'-azobis[N-(2-hydroxyethyl)-2-methyl-propionamidine] dihydro-chloride.
Various patents describe different synthetic polymers having an absorbing capacity for water and body fluids, e.g., cross-linked polymers and copolymers based on acrylic or methacrylic acid (U.S. 4 018 951; U.S. 4 066 583; U.S. 4 062 817; U.S. 4 066 583; DE-OS 26 13 135; DE-OS 27 12 043; DE-OS 28 13 634) or acrylamidopropane sulfonic acid copolymers (DE-PS 31 24 008).
These absorbents are virtually insoluble in water and absorb in equilibrium with aqueous liquids several times their own weight of water, urine, or other aqueous solutions. Some patents also de-scribe other properties of the synthetic absorbents in addition to the high liquid absorption capacity, e.g., low residual monomer content, low portion of water-soluble moieties, and high gel strength of the swollen polymer particles.
U.S. 4 529 739 and U.S. 4 649 164 describe polymers which have a porous structure and are based on methacrylic acid. They are obtained from ethyl acrylate/methacrylic acid copolymer latices under addition of compounds capable of separating carbon diox-ide, e.g., sodium hydrogencarbonate. Austrian patent AT 391 321 B describes cross-linked, porous acrylic polymers which are pro-duced by adding a nitrogen-containing blowing agent to the monomer solution. According to this method an N-containing blowing agent decomposing to ammonia and carbon dioxide at 80 to 250°C is added to acrylic acid, either before or after the po-lymerization. The acrylic acid is neutralized to the extent of 60 -100% with NaOH, KOH or NH3 , and the added quantity of N-containing blowing agent corresponds to an increase in the neu-tralization degree to 102 to 140%. Ammonium salts of inorganic or organic acids and urea are mentioned as blowing agents, am-monium carbonate being preferred. U.S. 5 118 719 also describes ammonium and alkali carbonates used as blowing agents which are added to the monomer solution prior to polymerization. Owing to the carbonate decomposition during polymerization, carbon di-oxide is formed and causes the formation of a "microcellular struc-ture" in the hydrogel. This may explain the improved absorption rate for liquids of the final product.
The use of alkali or ammonium carbonates prior to or during the polymerization of organic acids according to U.S. 4 529 739, U.S.
4 649 164, U.S. 5 1 18 719 results in the formation of carbon di-oxide during the neutralization of the monomer solution. Since C02 has a limited solubility in the monomer solution and in the polymer gel mass, only relatively small amounts of C02 can be incorporated into the polymer during polymerization or drying. Also, the alter-native according to AT 391 321 B, i.e., to add the blowing agent to the polymer gel prior to drying, does not result in the desired effect because of the superficial action of the aftertreatment. This method has the disadvantage that the added water amount must be removed during drying. Also, an excessive use of ammonia does not result in highly porous structures in swollen gel condi-tion, since ammonia is readily soluble in water or aqueous liquids.
Thus it is dissolved during swelling and the porosity of the hydro-gel particles substantially disappears. Moreover, the addition of ammonia and carbonate increases the pH of the final product to far beyond 7, and this greatly restricts the applicability of the products.
Starting from a water-soluble polymer based on acrylic acid, WO
88/09801 describes the production of a cross-linked, foamed ethyl acrylate/acrylic acid copolymer having a specific density of 0.20 g/cm3. The final product is manufactured in aqueous solution, and a subsequent cross-linkage and foaming operation under the addi-tion of a cross-linker and a blowing agent, e.g., sodium hydrogen-carbonate, p-toluenesulfonyl hydrazine or azo carboamide, is con-ducted in one process step. The drawback of this method is the fact that working in an aqueous solution is necessary and that the concentration is limited, e.g., to 18%-wt., because of the high viscosity in order to improve handling of the copolymer. Addi-tionally, large amounts of blowing agent, e.g., 27%-wt., relative to the copolymer, are required.
As is known from AT 391 321 B very small amounts of azo com-pounds, e.g., 0.056%-wt., relative to the monomer, are normally used as polymerization initiators. In case of higher concentrations of such radical formers, the excess of free radicals will result in polymers having a lower molecular weight and in products having insufficient absorbing properties.
Another feature of the known polymers capable of absorbing wa-ter or aqueous liquids is the fact that they cannot float on the liquid surface when placed into water or aqueous liquids in unswollen condition and after liquid absorption, unless they com-prise auxiliary agents, such as cork flour, as described in EP 0 285 404 B 1.
Accordingly, there was the object to avoid the above-mentioned drawbacks and to obtain absorbents having a porous structure, good absorption properties, in particular an improved absorption rate, and a low average total density of the individual particles, so that the polymer particles, particularly in swollen state, are able to float on the water surface.
Most surprisingly, it was found that water-swellable, cross-linked, particulate polymers having a porous structure and a high absorp-tion rate for water and aqueous liquids and a density of below 1 .0 g/cm3 in swollen condition and a density of above 1.0 g/cm3 in dry condition can be produced in higher concentrations by means of radical polymerization in aqueous solution by using at least one azo compound simultaneously as polymerization initiator and blowing agent. Suitable azo compounds are those having a half-time of 10 hours or more at a temperature ranging from 30 to 120°C, preferably in the temperature range of 60 to 120°C. The azo compounds are added to the monomer solution prior to po-lymerization. For preference, the following azo compounds are used:
1. Azonitrile-compounds:
2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropyl propionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1-azobis(cylcohexane-1-carbonitrile), AMENDED SHEET
1-[( 1-cyano-1-methyl ethyl)azo]formamide (2-(carbamoyl azo)isobutyronitrile, and 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile.
2. Azoamidine-compounds:
2,2'-azobis(2-methyl-N-phenylpropionamidine) dihydrochloride, 2,2'-azobis[N-(4-chlorophenyl)-2-methylpropionamidine] dihydro-chloride, 2,2'-azobis(N-(4-hydroxyphenyl)-2-methylpropionamidine] dihydro-chloride, 2,2'-azobis[N-(4-aminophenyl)- 2-methylpropionamidine] tetrahy-drochloride, 2,2'-azobis(2-methyl-N-(phenylmethyl)-propionamidine] dihydro-chloride, 2,2'-azobis[2-methyl-N-2-propenyl propionamidine] dihydrochlo-ride, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, and 2,2'-azobis[N-(2-hydroxyethyl)-2-methyl-propionamidine] dihydro-chloride.
3. Cyclic azoamidine-compounds:
2,2'-azobis[2-(5-methyl-2-imidazoline-2-yl)propane] dihydrochlo-ride, 2,2'-azobis(2-(2-imidazoline-2-yl)propane] dihydrochloride, 2,2'-azobis[2-(4,5,6,7-tetrahydro-1 H-1,3-diazepine-2-yl)propane]
dihydrochloride, 2,2'-azobis[2-(3,4,5,6-tetrahydropyrimidine-2-yl)propane] dihydro-chloride 2,2'-azobis[2-(5-hydroxy-3,4,5,6-tetrahydropyrimidine-2-yl)propane] dihydrochloride, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazoline-2-yl]propane} di-hydrochloride, and 2,2'-azobis[2-(2-imidazoline-2-yl)propane].
2,2'-azobis[2-(5-methyl-2-imidazoline-2-yl)propane] dihydrochlo-ride, 2,2'-azobis(2-(2-imidazoline-2-yl)propane] dihydrochloride, 2,2'-azobis[2-(4,5,6,7-tetrahydro-1 H-1,3-diazepine-2-yl)propane]
dihydrochloride, 2,2'-azobis[2-(3,4,5,6-tetrahydropyrimidine-2-yl)propane] dihydro-chloride 2,2'-azobis[2-(5-hydroxy-3,4,5,6-tetrahydropyrimidine-2-yl)propane] dihydrochloride, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazoline-2-yl]propane} di-hydrochloride, and 2,2'-azobis[2-(2-imidazoline-2-yl)propane].
4. Azoamide-compounds:
2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxy-ethyl]propionamide}, 2,2'-azobis{2-methyl-N-[ 1,1,-bis(hydroxymethyl)ethyl]propionamide}, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], and 2,2'-azobis(2-methylpropionamide) dihydrate.
2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxy-ethyl]propionamide}, 2,2'-azobis{2-methyl-N-[ 1,1,-bis(hydroxymethyl)ethyl]propionamide}, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], and 2,2'-azobis(2-methylpropionamide) dihydrate.
5. Alkylazo and other azo compounds:
2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), and 2,2'-azobis[hydroxymethyl)propionitrile].
In swollen condition, the water-swellable, cross-linked, particulate polymers according to the present invention preferably have an average particle density of 0.900 to 0.999 g/cm3 and a particle-size distribution of the particles in a range of 0.1 to 5.0 mm, in particular of 0.8 to 3 mm.
The monomers primarily used are acrylic acid, methacrylic acid, acrylamidopropane sulfonic acid, acrylamidomethylpropane sulfonic acid, the salts of these acids, in particular alkali, alkaline-earth, and ammonium salts, as well as acrylamide and methacrylamide. The above monomers may either be used alone for the production of homopolymers or in mixture with one another for the production of copolymers. For the pro-duction of copolymers the above monomers may also be used with other water-soluble monomers, such as water-soluble polym-erizable acids, preferably malefic acid, fumaric acid, itaconic acid, 6 a 2179775 or vinyl sulfonic acid, or the salts of these acids. Further suitable monomers are acrylonitrile, methacrylonitrile, vinyl pyridine, vinyl acetate, vinyl pyrrolidone, hydroxy group-containing esters of polymerizable acids, in particular the hydroxyethyl- and hydroxypropyl esters of acrylic and methacrylic acid, as well as amino group-containing and ammonium group-containing esters and amides of polymerizable acids, such as the dialkyl aminoesters, in particular the dimethyl-and diethylaminoalkyl esters of acrylic and methacrylic acid, as well as the trimethyl- and triethylammonium alkyl esters, as well as the corresponding amides. Small amounts of water-insoluble monomers may also additionally be copolymerized with the above monomers. For instance, esters of the acrylic and/or methacrylic acid with C1-Clo alcohols, styrene, and alkylated styrenes. In general the portion of water-soluble monomers amounts to 80 to 100%-wt., relative to the total monomers. In general the water-insoluble (hydrophobic) monomers come up to 0 to 20%-wt., preferably up to 10%-wt., of the monomers. The polymerization may also completely or partially be carried out as graft polymerization in the presence of other polymeric substances, such as oligo- and polysaccharides, or polyvinyl alcohol.
Utilizing the different decomposition properties these azo com-pounds may also be used in combination. The concentration of the blowing agent additive in the monomer solution amounts to 0.1 to 5.0%-wt., preferably 0.2 to 2.0%-wt.
The water-absorbing polymeric absorbents are mostly obtained by using at least one cross-linking monomer. Compounds which com-prise at least 2 or more functional groups, e.g., double-bonds or epoxy groups, and are capable of incorporating themselves into _ the growing polymer chains during polymerization are used as cross-linking monomers. Thus, cross-links at different sites in the polymer are formed in the polymer during polymerization or during a subsequent reaction of functional groups. These cross-links couple the individual polymer chains and cause the polymer parti-cles to swellv in a liquid without dissont~on. The properties of the cross-linked polymer are determined by the chemical structure of the cross-linking agent, the number of cross-links and also by the distribution in the polymer chains. Examples of cross-linking monomers include bi- or polyfunctional monomers, e.g., amides, g such as methylene bisacrylamide or methylene methacrylamide or ethylene bisacrylamide, also esters of polyols, such as diacrylates or triacrylates, e.g., butanediol- or ethylene glycol diacrylate, trimethylol propane triacrylate, glycidyl methacrylate, glycerol triglycidyl ether, vinyl methacrylate and allyl compounds, such as allyl (meth)acrylate, triallyl cyanurate, malefic acid diallyl ester, polyallyl ester, tetraallyloxyethane, triallyl amine, tetraallyl ethyl-enediamine, allyl esters of phosphoric acid or of phosphorous acid, and cross-linkable monomers, such as N-methylol compounds of amides, such as the methacrylamide or acrylamide, and the ethers derived therefrom. The portion of cross-linking comonomers amounts to about 0.01 to 10%-wt., preferably 0.10 to 2.0%-wt., relative to the total monomers. In case of an optimum incorpora-tion of the cross-linking agent into the polymer, cross-linked poly-mers will result in which the cross-links are distributed evenly so that non-cross-linked or even uncross-linked regions, i.e. water-soluble, low-molecular portions in the polymer, will scarcely be found. An adequate concentration and even distribution of cross-links in the polymer will result in a product having an optimum re-tention capacity for water and aqueous liquids and an optimum gel strength in swollen condition.
Polymerization may be started by using a redox catalyst system as initiator or by means of photopolymerization. The redox catalyst system normally consists of two components, an inorganic or or-ganic peroxide-containing compound and a reducing component, such as sulfite, hydrosulfite, thiosulfate, sulfinic acid, ascorbic acid and its salts, copper-, iron(II)-, or manganese salts. Suitable inorganic peroxide compounds include the alkali or ammonium peroxides, such as potassium peroxide sulfate, hydrogen peroxide or peroxomono- or diphosphoric acid and their salts, or organic peroxides, such as benzoyl peroxide, butyl hydroperoxide. In addi-tion to the usual two-component first initiator system further will ~ 179775 be used one or several azo compounds as initiator and blowing compounds. For photopolymerization which may be initiated by UV-containing light so-called photoinitiators are used, e.g., ben-zoin or benzoin derivatives, such as benzoin ether, benzil, benzil ketal and other derivatives, acrylic diazonium salts, or acetophe-none derivatives. Also here, the used blowing agents may serve as initiators, wherein the dosage of the UV-light is important for the polymerization. The amounts of the peroxide-containing compo-nent and of the reducing component are in the range of 0.0005 to 0.5%-wt., preferably 0.001 to 0.1 %-wt., relative to the monomer solution. The amount of photoinitiators not being azo compounds is in the range of 0.001 to 0.1 %-wt., preferably of 0.002 to 0.05%-wt., relative to the monomer solution.
The polymerization may be carried out according to the known methods in solution or suspension. It is preferred, however, that the polymerization be carried out in aqueous solution, either dis-continuously in a polymerization vessel or continuously on an endless belt, for instance, according to DE-PS 35 44 770. In a practically adiabatic course of polymerization, an aqueous polymer gel results when an adequate initial concentration of 15 to 50%-wt. of the monomers, relative to the monomer solution is used. By choosing the initial monomer concentration and a low starting temperature ranging from 0 to 50°C, preferably from 10 to 25°C, the polymerization can be conducted such that the maximum tem-perature in the resulting aqueous polymer gel is in the range of 100 - 130°C, preferably of 1 10 - 120°C. Polymerization may be conducted under normal or increased pressure, normal pressure being preferred.
In the end phase of polymerization the consistency of the resulting polymer gel is sufficiently strong to keep the nitrogen, which forms in this production phase during the partial decomposition of the initiator and blowing agent, in a finely dispersed manner enclosed as separate gas bubbles at elevated temperatures, e.g., of 100 to 120°C; the gas bubbles have a relatively small volume and the pressure may optionally be increased.
When the polymerization is completed, the polymer gel such pro-duced is crumbled and dried at temperatures of 100 to 240°C, preferably at 120 to 180°C. During drying, the portion of excess azo compound which has not decomposed during polymerization decomposes at these temperatures. The liberating nitrogen is also enclosed and kept in the dry polymer in the form of very small micro-bubbles. Thereby a polymer forms which has a very porous structure and the average total density of the polymer particles obtained after grinding is below the density of the polymer itself.
When the polymers according to the present invention are used together with water or aqueous liquids, the finely dispersed gas volumes increase during the swelling process, thereby a swollen hydrogel with a reduced gel strength in equilibrium state results.
At the same time, the average total density of the swollen parti-cles decreases continuously in dependence on the swelling degree, until a value of less than 1.0 g/cm3 is achieved. The polymer particles which were heavier than water in the solid, dry state first, rise up and float in swollen condition on the water or liquid surface.
The polymers according to the present invention are used in prod-ucts for the absorption and/or retention of water and/or aqueous liquids, in particular of body fluids, such as urine or blood, pref-erably in absorbent disposables for hygienic purposes, such as diapers, incontinence articles, sanitary napkins and tampons, as well as for medical purposes.
In addition to the use as liquid-absorbing component having an AMENDED SHEET
~o a 2 179 775 increased absorption rate in hygiene products, the polymers ac-cording to the present invention may also advantageously be used for the following purposes:
1 ) The polymers may be used for a controlled and selective release of additional substances to other bodies; these substances have either been incorporated into the polymers subsequently, e.g. by absorption, or are already present in the polymer; for example for AMENDED SHEET
the dosage of drugs, nutrients, insecticides and herbicides into an aqueous medium, preferably in large water containers, water pools or on large bodies of water, such as in inland water or in the sea.
Another example is the release of nutrients to water plants, or to growth media for the cultivation of plants. The polymers which are floatable both in freshwater and in sea-water may selectively be used for insect control, e.g., against mosquito larvae, or in the distribution of herbicides, preferably on larger bodies of water. In this connection, the active substances contained in the polymer are advantageously primarily be distributed on the water surface.
2) Owing to their large surface, these polymers may also find a limited use in the absorption and/or retention of substances dis-solved or dispersed in the water, this also applies to partially wa-ter-soluble or even water-insoluble substances floating on the water surface.
3) The polymers may be used for the production of absorption materials in which the polymers according to the present invention are to be separated from other, non-floatable materials (e.g, cellu-lose, plastics, earth, clay, and the like) because of the different specific weights of the polymers in swollen condition, e.g., in recycling.
If the polymers according to the present invention are used in ab-sorbent articles, the absorbent articles are comminuted mechani-cally and placed into water or aqueous liquids, and the polymer particles are separated in swollen state.
Examples of substances suitable for the incorporation in the polymers according to the present invention include, nutrients for plants, fertilizers, herbicides, fungicides, insecticides, ~~ a - 2 179 775 other plant protective agents, disinfectants, pharmaceutic and cosmetic agents, microbicidal agents, nematocides, dyes, illuminants, fragrances for perfuming and others, for example those described in DE 40 29 59 1 Al. The active ingredients may be incorporated in the polymer by direct addition to the monomer solution, provided the polymerization course is not disturbed. In case these substances affect the polymerization, they may be included either during or after completed polymerization by means of incorporating them into the obtained polymer gel. This is described, for example, in DE 40 29 591 A1, DE 40 29 592 A1, or DE 40 29 593 A1. Substances having a density of below 1.0 g/cm3, such as ground plastic or natural cellular plastics or cork flour, may additionally be incorporated in this manner. For the re-lease of the active ingredients contained in the polymer in a con-trolled manner it is advantageous that the incorporated substances are water-soluble. On the other hand, in particular when a slow release of the active ingredients to other bodies is desired, sub-stances which are insoluble or only partially soluble in water may also be used. A good water dispersibility of the active substances may also be sufficient for their use according to the present in-vention.
The present invention will be illustrated in more detail by means of the following examples.
Example 1 In a polymerization vessel, 0.9 g methylene bisacrylamide and 192 g acrylamide were dissolved in 500 g water first and mixed with 84 g acrylic acid. Then, the monomer solution was neutralized with 102 g potassium hydroxide solution (45%), cooled to 10°C
and blown out with nitrogen. After addition of the catalyst solu-tions (1.6 g sodium peroxidisulfate, 0.2 g hydrogen peroxide (35%) and 0.01 g ascorbic acid) and 10 g 2,2'-azobis(2-methyl-propionamidine)dihydrochloride used as blowing agent, the polym-erization was initiated. Thorough mixing of the catalyst solutions with the monomer solution is a precondition for a homogeneous polymerization in the whole polymer block. The maximum tem-perature of 100°C (in a well-insulated polymerization vessel) was reached within 10 minutes. After completed polymerization, the polymer gel was crumbled, dried at 120°C and ground to the de-sired size fraction. A cross-linked potassium acrylate/acrylamide copolymer was obtained which had a porous structure resulting from the entrapped nitrogen bubbles.
The screened size fraction 1000 to 2000 Nm was used for addi-tional examinations:
average particle density Idry): 1.30 g/cm3 average particle density (swollen): 0.96 g/cm3 floatability in tap water: 100% of particles after 1 h 100% of particles after 120h floatability in 0.9% NaCI-solution: 100% of particles after 1 h 100% of particles after 120h floatability in sea-water: 100% of particles after 1 h 100% of particles after 24h 32% of particles after 120h The absorption capacity amounted to 140 ml/g of tap water, 1 10 ml/g of 0.9% NaCI-solution, and 75 ml/g of sea-water.
The average particle density was determined pycnometrically. The particle density of the swollen particles, which depends on the swelling degree, was determined after 1 hour of swelling.
Example 2 The polymerization was conducted with 20 g blowing agent 2,2'-azobis(2-methylpropionamidine)dihydrochloride under the same conditions as in Example 1 . After polymerization, the polymer gel was crumbled, dried at 120°C, and ground to the desired size fraction. A cross-linked potassium acrylate/acrylamide copolymer having a porous structure and entrapped nitrogen bubbles re-sulted.
The screened size fraction 1000 to 2000 Nm was used for further examinations:
average particle density 1.25 g/cm3 (dry):
average particle density 0.95 g/cm' (swollen):
floatability in tap water: 100% of particles 1 after h 100% of particles 120h after floatability in 0.9% NaCI-solution:100% of particles 1 after h 100% of particles 120h after floatability in sea-water: 100% of particles 1 after h 100% of particles 24h after 50% of particles after 120h The absorption capacity amounted to 135 ml/g of tap water, 1 10 ml/g of 0.9% NaCI-solution, and 85 ml/g of sea-water.
Examples 3 and 4 The polymerization was conducted under the same conditions as in Examples 1 and 2 a) with 2.9 g and b) with 10.0 g blowing agent 4,4'-azobis(4-cyanovaleric acid). After polymerization, the polymer gel was crumbled, dried at 120°C and ground to the de-sired size fraction. A cross-linked potassium acrylate/acrylamide copolymer resulted having a porous structure and entrapped nitro-gen bubbles.
The screened size fraction 1000 to 2000 Nm was used for further examinations:
a) average particle density (dry): 1.40 g/cm3 average particle density (swollen): 0.995 g/cm3 b) average particle density (dry): 1.29 g/cm3 average particle density (swollen): 0.99 g/cm3 floatability in tap water: a) 35% of particles after 1 h b) 85% of particles after 1 h Examples 5 and 6 The polymerization was conducted under the same conditions as in Examples 3 and 4, except that a terpolymer of acrylamide, acrylic acid, and acrylamido(2-methylpropane)sulfonic acid (AMPS) was prepared in the ratio 70/28/02 mole-%. 5.0 g 4,4'-azobis(4-cyanovaleric acid) was added as blowing agent to the monomer solution. After completion of the polymerization, the polymer gel was crumbled, dried at 120°C, and ground to the desired size fraction. A cross-linked potassium acrylate/acrylamide/AMPS-ter-polymer having a porous structure and entrapped nitrogen bubbles resulted. The batch was repeated twice to establish reproducibil-ity.
a) average particle density (dry): 1.31 g/cm3 average particle density (swollen): 0.985 g/cm' b) average particle density ldry): 1.33 g/cm' average particle density (swollen): 0.98 g/cm3 floatability in tap water: a) 80% of particles after 1 h b) 82% of particles after 1 h Examples 7 and 8 The polymerization was conducted under the same conditions as in Example 1 a) with 2.9 g and b) with 10.0 g blowing agent 2,2'-azobis[2-(2-imidazoline-2-yl)propane]dihydrochloride. After com-pleted polymerization, the polymer gel was crumbled, dried at 120°C, and ground to the desired size fraction. A cross-linked co-polymer resulted having a porous structure and entrapped nitrogen bubbles.
The screened size fraction 1000 to 2000 um was used for further examinations:
a) average particle density (dry): 1.49 g/cm3 average particle density (swollen): 0.995 g/cm3 b) average particle density (dry): 1.45 g/cm3 average particle density (swollen): 0.99 g/cm3 floatability in tap water: a) 45% of particles after 1 h b) 58% of particles after 1 h Examples 9 to 13 The polymerization was conducted under the same conditions as in Example 1 with 2.9 g of each of the following blowing agents:
a) 2,2'-azobis[2-(4,5,6,7-tetrahydro-1 H-1,3-diazepine-2-yl)pro-pane] dihydrochloride, b) 2,2'-azobis[2-(5-hydroxy-3,4,5,6-tetrahydropyrimidine-2-yl)pro-pane] dihydrochloride, c) 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazoline-2-yl]propane}
dihydrochloride, and d) 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide].
After completed polymerization, the polymer gel was crumbled, dried at 120°C, and ground to the desired size fraction. A cross-linked copolymer resulted having a porous structure and entrapped nitrogen bubbles.
The screened size fraction 1000 to 2000 Nm was used for further examinations:
average particle density (dry): a) 1.49 g/cm3 b) 1.54 g/cm3 c) 1.51 g/cm3 d) 1.54 g/cm3 average particle density (swollen): a) 0.99 g/cm3 b) 0.99 g/cm3 c) 0.995 g/cm3 d) 0.995 g/cm3 floatability in tap water: a) 62% of particles after 1 h b) 58% of particles after 1 h c) 45% of particles after 1 h d) 32% of particles after 1 h Example 14 In a polymerization vessel, 256 g acrylic acid was placed first, di-luted with 335 g water and neutralized with 209 g sodium hydro-gencarbonate. Then, 1.8 g triallylamine was dissolved in the monomer solution, the monomer solution cooled to 10°C and blown out with nitrogen. After addition of the catalyst solutions (0.9 g sodium peroxidisulfate, 0.2 g hydrogen peroxide (35%), and 0.01 g ascorbic acid) and 8.8 g 4,4'-azobis(4-cyanovaleric acid) used as blowing agent, the polymerization was started.
Within 7 minutes the maximum temperature of 103°C was reached. After polymerization, the polymer gel was crumbled, dried at 150°C and ground to the desired size fraction. A cross-linked acrylic acid homopolymer, partially as sodium salt, was ob-tained having a porous structure resulting from the entrapped ni-trogen bubbles.
The screened size fraction 850 to 2000 Nm was used for further examinations:
average particle density (dry): 1.70 g/cm3 average particle density (swollen): 0.99 g/cm3 floatability in tap water: 86% of particles after 1 h 80% of particles after 24 h floatability in 0.9% NaCI-solution: 65% of particles after 1 h floatability in sea-water: 60% of particles after 1 h Example 15 Under the same conditions as in Example 14 the polymerization was conducted using also 8.8 g blowing agent 4,4'-azobis(4-cya-novaleric acid), differing from Example 14, however, the acrylic acid monomer solution was neutralized with 310 g potassium hy-droxide solution. After completion of the polymerization, the poly-mer gel was crumbled, dried at 150°C, and ground to the desired size fraction. A cross-linked acrylic acid homopolymer, partially as potassium salt, was obtained having a porous structure and en-trapped nitrogen bubbles.
The screened size fraction 850 to 2000 Nm was used for further examinations:
average particle density (dry): 1.63 g/cm3 average particle density (swollen): 0.97 g/cm3 floatability in tap water: 100% of particles after 1 h 96% of particles after 24 h floatability in 0.9% NaCI-solution: 95% of particles after 1 h floatability in sea-water: 80% of particles after 1 h Examples 16 to 21 256 g acrylic acid was placed in a polymerization vessel first, di-luted with 335 g water and neutralized with 200 g sodium hydrox-ide solution (50%). Then, 0.77 g triallylamine was dissolved in the monomer solution, the monomer solution cooled to 10°C, blown out with nitrogen, and the polymerization started with the same catalyst system as in Example 14. The following table 1 shows the added amounts of 2,2'-azobis(2-methylpropionamidine)dihydro-chloride (ABAH) and 4,4'-azobis(4-cyanovaleric acid) (ABCVA).
The maximum temperatures of 100 to 102°C were achieved within 7 to 12 minutes. After completion of the polymerization, ~ 179 775 the polymer gels were crumbled, dried at 150°C and ground to the desired size fraction. The thus produced cross-linked acrylic acid homopolymers, partially as sodium salts, have a porous structure which was achieved by the entrapped nitrogen bubbles.
For comparison purposes, another polymer with only 0.08%-wt.
of ABAH was prepared which could not have a porous structure owing to the small amount of ABAH which completely decomposed during polymerization.
The screened size fractions 150 to 850 Nm were then used to de-termine the absorption rate and the absorption capacity according to the tea bag test.
The liquid absorption of 0.2 g test substance was determined gravimetrically in a tea bag after 15, 60, and 600 seconds. The retention value was also determined gravimetrically after centrifug-ing in a centrifuge, e.g. in a commercial spin dryer, at 1400 rpm, the value was then expressed in terms of 1 g of product. 0.9%
NaCI-solution was used as test liquid.
Table 1: Dependence of absorption rate and absorption capacity on the added ABAH or ABCVA amounts AdditiveAdded Tea bag Tea bag Tea bag amount 15 sec. 60 sec. Retention (%-wt.) (g/g) (g/g) (g/g) Example 16 ABAH 0.28 10.5 21.1 34.3 Example 17 ABAH 0.58 12.4 25.8 38.8 Example 18 ABAH 1.08 18.2 34.4 40.2 Example 19 ABCVA 0.2 10.2 16.7 32.9 Example 20 ABCVA 0.5 9.7 17.6 36.7 Example 21 ABCVA 1.0 10.1 27.7 41 .0 Comparison ABAH 0.08 8.1 13.1 33.6
2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), and 2,2'-azobis[hydroxymethyl)propionitrile].
In swollen condition, the water-swellable, cross-linked, particulate polymers according to the present invention preferably have an average particle density of 0.900 to 0.999 g/cm3 and a particle-size distribution of the particles in a range of 0.1 to 5.0 mm, in particular of 0.8 to 3 mm.
The monomers primarily used are acrylic acid, methacrylic acid, acrylamidopropane sulfonic acid, acrylamidomethylpropane sulfonic acid, the salts of these acids, in particular alkali, alkaline-earth, and ammonium salts, as well as acrylamide and methacrylamide. The above monomers may either be used alone for the production of homopolymers or in mixture with one another for the production of copolymers. For the pro-duction of copolymers the above monomers may also be used with other water-soluble monomers, such as water-soluble polym-erizable acids, preferably malefic acid, fumaric acid, itaconic acid, 6 a 2179775 or vinyl sulfonic acid, or the salts of these acids. Further suitable monomers are acrylonitrile, methacrylonitrile, vinyl pyridine, vinyl acetate, vinyl pyrrolidone, hydroxy group-containing esters of polymerizable acids, in particular the hydroxyethyl- and hydroxypropyl esters of acrylic and methacrylic acid, as well as amino group-containing and ammonium group-containing esters and amides of polymerizable acids, such as the dialkyl aminoesters, in particular the dimethyl-and diethylaminoalkyl esters of acrylic and methacrylic acid, as well as the trimethyl- and triethylammonium alkyl esters, as well as the corresponding amides. Small amounts of water-insoluble monomers may also additionally be copolymerized with the above monomers. For instance, esters of the acrylic and/or methacrylic acid with C1-Clo alcohols, styrene, and alkylated styrenes. In general the portion of water-soluble monomers amounts to 80 to 100%-wt., relative to the total monomers. In general the water-insoluble (hydrophobic) monomers come up to 0 to 20%-wt., preferably up to 10%-wt., of the monomers. The polymerization may also completely or partially be carried out as graft polymerization in the presence of other polymeric substances, such as oligo- and polysaccharides, or polyvinyl alcohol.
Utilizing the different decomposition properties these azo com-pounds may also be used in combination. The concentration of the blowing agent additive in the monomer solution amounts to 0.1 to 5.0%-wt., preferably 0.2 to 2.0%-wt.
The water-absorbing polymeric absorbents are mostly obtained by using at least one cross-linking monomer. Compounds which com-prise at least 2 or more functional groups, e.g., double-bonds or epoxy groups, and are capable of incorporating themselves into _ the growing polymer chains during polymerization are used as cross-linking monomers. Thus, cross-links at different sites in the polymer are formed in the polymer during polymerization or during a subsequent reaction of functional groups. These cross-links couple the individual polymer chains and cause the polymer parti-cles to swellv in a liquid without dissont~on. The properties of the cross-linked polymer are determined by the chemical structure of the cross-linking agent, the number of cross-links and also by the distribution in the polymer chains. Examples of cross-linking monomers include bi- or polyfunctional monomers, e.g., amides, g such as methylene bisacrylamide or methylene methacrylamide or ethylene bisacrylamide, also esters of polyols, such as diacrylates or triacrylates, e.g., butanediol- or ethylene glycol diacrylate, trimethylol propane triacrylate, glycidyl methacrylate, glycerol triglycidyl ether, vinyl methacrylate and allyl compounds, such as allyl (meth)acrylate, triallyl cyanurate, malefic acid diallyl ester, polyallyl ester, tetraallyloxyethane, triallyl amine, tetraallyl ethyl-enediamine, allyl esters of phosphoric acid or of phosphorous acid, and cross-linkable monomers, such as N-methylol compounds of amides, such as the methacrylamide or acrylamide, and the ethers derived therefrom. The portion of cross-linking comonomers amounts to about 0.01 to 10%-wt., preferably 0.10 to 2.0%-wt., relative to the total monomers. In case of an optimum incorpora-tion of the cross-linking agent into the polymer, cross-linked poly-mers will result in which the cross-links are distributed evenly so that non-cross-linked or even uncross-linked regions, i.e. water-soluble, low-molecular portions in the polymer, will scarcely be found. An adequate concentration and even distribution of cross-links in the polymer will result in a product having an optimum re-tention capacity for water and aqueous liquids and an optimum gel strength in swollen condition.
Polymerization may be started by using a redox catalyst system as initiator or by means of photopolymerization. The redox catalyst system normally consists of two components, an inorganic or or-ganic peroxide-containing compound and a reducing component, such as sulfite, hydrosulfite, thiosulfate, sulfinic acid, ascorbic acid and its salts, copper-, iron(II)-, or manganese salts. Suitable inorganic peroxide compounds include the alkali or ammonium peroxides, such as potassium peroxide sulfate, hydrogen peroxide or peroxomono- or diphosphoric acid and their salts, or organic peroxides, such as benzoyl peroxide, butyl hydroperoxide. In addi-tion to the usual two-component first initiator system further will ~ 179775 be used one or several azo compounds as initiator and blowing compounds. For photopolymerization which may be initiated by UV-containing light so-called photoinitiators are used, e.g., ben-zoin or benzoin derivatives, such as benzoin ether, benzil, benzil ketal and other derivatives, acrylic diazonium salts, or acetophe-none derivatives. Also here, the used blowing agents may serve as initiators, wherein the dosage of the UV-light is important for the polymerization. The amounts of the peroxide-containing compo-nent and of the reducing component are in the range of 0.0005 to 0.5%-wt., preferably 0.001 to 0.1 %-wt., relative to the monomer solution. The amount of photoinitiators not being azo compounds is in the range of 0.001 to 0.1 %-wt., preferably of 0.002 to 0.05%-wt., relative to the monomer solution.
The polymerization may be carried out according to the known methods in solution or suspension. It is preferred, however, that the polymerization be carried out in aqueous solution, either dis-continuously in a polymerization vessel or continuously on an endless belt, for instance, according to DE-PS 35 44 770. In a practically adiabatic course of polymerization, an aqueous polymer gel results when an adequate initial concentration of 15 to 50%-wt. of the monomers, relative to the monomer solution is used. By choosing the initial monomer concentration and a low starting temperature ranging from 0 to 50°C, preferably from 10 to 25°C, the polymerization can be conducted such that the maximum tem-perature in the resulting aqueous polymer gel is in the range of 100 - 130°C, preferably of 1 10 - 120°C. Polymerization may be conducted under normal or increased pressure, normal pressure being preferred.
In the end phase of polymerization the consistency of the resulting polymer gel is sufficiently strong to keep the nitrogen, which forms in this production phase during the partial decomposition of the initiator and blowing agent, in a finely dispersed manner enclosed as separate gas bubbles at elevated temperatures, e.g., of 100 to 120°C; the gas bubbles have a relatively small volume and the pressure may optionally be increased.
When the polymerization is completed, the polymer gel such pro-duced is crumbled and dried at temperatures of 100 to 240°C, preferably at 120 to 180°C. During drying, the portion of excess azo compound which has not decomposed during polymerization decomposes at these temperatures. The liberating nitrogen is also enclosed and kept in the dry polymer in the form of very small micro-bubbles. Thereby a polymer forms which has a very porous structure and the average total density of the polymer particles obtained after grinding is below the density of the polymer itself.
When the polymers according to the present invention are used together with water or aqueous liquids, the finely dispersed gas volumes increase during the swelling process, thereby a swollen hydrogel with a reduced gel strength in equilibrium state results.
At the same time, the average total density of the swollen parti-cles decreases continuously in dependence on the swelling degree, until a value of less than 1.0 g/cm3 is achieved. The polymer particles which were heavier than water in the solid, dry state first, rise up and float in swollen condition on the water or liquid surface.
The polymers according to the present invention are used in prod-ucts for the absorption and/or retention of water and/or aqueous liquids, in particular of body fluids, such as urine or blood, pref-erably in absorbent disposables for hygienic purposes, such as diapers, incontinence articles, sanitary napkins and tampons, as well as for medical purposes.
In addition to the use as liquid-absorbing component having an AMENDED SHEET
~o a 2 179 775 increased absorption rate in hygiene products, the polymers ac-cording to the present invention may also advantageously be used for the following purposes:
1 ) The polymers may be used for a controlled and selective release of additional substances to other bodies; these substances have either been incorporated into the polymers subsequently, e.g. by absorption, or are already present in the polymer; for example for AMENDED SHEET
the dosage of drugs, nutrients, insecticides and herbicides into an aqueous medium, preferably in large water containers, water pools or on large bodies of water, such as in inland water or in the sea.
Another example is the release of nutrients to water plants, or to growth media for the cultivation of plants. The polymers which are floatable both in freshwater and in sea-water may selectively be used for insect control, e.g., against mosquito larvae, or in the distribution of herbicides, preferably on larger bodies of water. In this connection, the active substances contained in the polymer are advantageously primarily be distributed on the water surface.
2) Owing to their large surface, these polymers may also find a limited use in the absorption and/or retention of substances dis-solved or dispersed in the water, this also applies to partially wa-ter-soluble or even water-insoluble substances floating on the water surface.
3) The polymers may be used for the production of absorption materials in which the polymers according to the present invention are to be separated from other, non-floatable materials (e.g, cellu-lose, plastics, earth, clay, and the like) because of the different specific weights of the polymers in swollen condition, e.g., in recycling.
If the polymers according to the present invention are used in ab-sorbent articles, the absorbent articles are comminuted mechani-cally and placed into water or aqueous liquids, and the polymer particles are separated in swollen state.
Examples of substances suitable for the incorporation in the polymers according to the present invention include, nutrients for plants, fertilizers, herbicides, fungicides, insecticides, ~~ a - 2 179 775 other plant protective agents, disinfectants, pharmaceutic and cosmetic agents, microbicidal agents, nematocides, dyes, illuminants, fragrances for perfuming and others, for example those described in DE 40 29 59 1 Al. The active ingredients may be incorporated in the polymer by direct addition to the monomer solution, provided the polymerization course is not disturbed. In case these substances affect the polymerization, they may be included either during or after completed polymerization by means of incorporating them into the obtained polymer gel. This is described, for example, in DE 40 29 591 A1, DE 40 29 592 A1, or DE 40 29 593 A1. Substances having a density of below 1.0 g/cm3, such as ground plastic or natural cellular plastics or cork flour, may additionally be incorporated in this manner. For the re-lease of the active ingredients contained in the polymer in a con-trolled manner it is advantageous that the incorporated substances are water-soluble. On the other hand, in particular when a slow release of the active ingredients to other bodies is desired, sub-stances which are insoluble or only partially soluble in water may also be used. A good water dispersibility of the active substances may also be sufficient for their use according to the present in-vention.
The present invention will be illustrated in more detail by means of the following examples.
Example 1 In a polymerization vessel, 0.9 g methylene bisacrylamide and 192 g acrylamide were dissolved in 500 g water first and mixed with 84 g acrylic acid. Then, the monomer solution was neutralized with 102 g potassium hydroxide solution (45%), cooled to 10°C
and blown out with nitrogen. After addition of the catalyst solu-tions (1.6 g sodium peroxidisulfate, 0.2 g hydrogen peroxide (35%) and 0.01 g ascorbic acid) and 10 g 2,2'-azobis(2-methyl-propionamidine)dihydrochloride used as blowing agent, the polym-erization was initiated. Thorough mixing of the catalyst solutions with the monomer solution is a precondition for a homogeneous polymerization in the whole polymer block. The maximum tem-perature of 100°C (in a well-insulated polymerization vessel) was reached within 10 minutes. After completed polymerization, the polymer gel was crumbled, dried at 120°C and ground to the de-sired size fraction. A cross-linked potassium acrylate/acrylamide copolymer was obtained which had a porous structure resulting from the entrapped nitrogen bubbles.
The screened size fraction 1000 to 2000 Nm was used for addi-tional examinations:
average particle density Idry): 1.30 g/cm3 average particle density (swollen): 0.96 g/cm3 floatability in tap water: 100% of particles after 1 h 100% of particles after 120h floatability in 0.9% NaCI-solution: 100% of particles after 1 h 100% of particles after 120h floatability in sea-water: 100% of particles after 1 h 100% of particles after 24h 32% of particles after 120h The absorption capacity amounted to 140 ml/g of tap water, 1 10 ml/g of 0.9% NaCI-solution, and 75 ml/g of sea-water.
The average particle density was determined pycnometrically. The particle density of the swollen particles, which depends on the swelling degree, was determined after 1 hour of swelling.
Example 2 The polymerization was conducted with 20 g blowing agent 2,2'-azobis(2-methylpropionamidine)dihydrochloride under the same conditions as in Example 1 . After polymerization, the polymer gel was crumbled, dried at 120°C, and ground to the desired size fraction. A cross-linked potassium acrylate/acrylamide copolymer having a porous structure and entrapped nitrogen bubbles re-sulted.
The screened size fraction 1000 to 2000 Nm was used for further examinations:
average particle density 1.25 g/cm3 (dry):
average particle density 0.95 g/cm' (swollen):
floatability in tap water: 100% of particles 1 after h 100% of particles 120h after floatability in 0.9% NaCI-solution:100% of particles 1 after h 100% of particles 120h after floatability in sea-water: 100% of particles 1 after h 100% of particles 24h after 50% of particles after 120h The absorption capacity amounted to 135 ml/g of tap water, 1 10 ml/g of 0.9% NaCI-solution, and 85 ml/g of sea-water.
Examples 3 and 4 The polymerization was conducted under the same conditions as in Examples 1 and 2 a) with 2.9 g and b) with 10.0 g blowing agent 4,4'-azobis(4-cyanovaleric acid). After polymerization, the polymer gel was crumbled, dried at 120°C and ground to the de-sired size fraction. A cross-linked potassium acrylate/acrylamide copolymer resulted having a porous structure and entrapped nitro-gen bubbles.
The screened size fraction 1000 to 2000 Nm was used for further examinations:
a) average particle density (dry): 1.40 g/cm3 average particle density (swollen): 0.995 g/cm3 b) average particle density (dry): 1.29 g/cm3 average particle density (swollen): 0.99 g/cm3 floatability in tap water: a) 35% of particles after 1 h b) 85% of particles after 1 h Examples 5 and 6 The polymerization was conducted under the same conditions as in Examples 3 and 4, except that a terpolymer of acrylamide, acrylic acid, and acrylamido(2-methylpropane)sulfonic acid (AMPS) was prepared in the ratio 70/28/02 mole-%. 5.0 g 4,4'-azobis(4-cyanovaleric acid) was added as blowing agent to the monomer solution. After completion of the polymerization, the polymer gel was crumbled, dried at 120°C, and ground to the desired size fraction. A cross-linked potassium acrylate/acrylamide/AMPS-ter-polymer having a porous structure and entrapped nitrogen bubbles resulted. The batch was repeated twice to establish reproducibil-ity.
a) average particle density (dry): 1.31 g/cm3 average particle density (swollen): 0.985 g/cm' b) average particle density ldry): 1.33 g/cm' average particle density (swollen): 0.98 g/cm3 floatability in tap water: a) 80% of particles after 1 h b) 82% of particles after 1 h Examples 7 and 8 The polymerization was conducted under the same conditions as in Example 1 a) with 2.9 g and b) with 10.0 g blowing agent 2,2'-azobis[2-(2-imidazoline-2-yl)propane]dihydrochloride. After com-pleted polymerization, the polymer gel was crumbled, dried at 120°C, and ground to the desired size fraction. A cross-linked co-polymer resulted having a porous structure and entrapped nitrogen bubbles.
The screened size fraction 1000 to 2000 um was used for further examinations:
a) average particle density (dry): 1.49 g/cm3 average particle density (swollen): 0.995 g/cm3 b) average particle density (dry): 1.45 g/cm3 average particle density (swollen): 0.99 g/cm3 floatability in tap water: a) 45% of particles after 1 h b) 58% of particles after 1 h Examples 9 to 13 The polymerization was conducted under the same conditions as in Example 1 with 2.9 g of each of the following blowing agents:
a) 2,2'-azobis[2-(4,5,6,7-tetrahydro-1 H-1,3-diazepine-2-yl)pro-pane] dihydrochloride, b) 2,2'-azobis[2-(5-hydroxy-3,4,5,6-tetrahydropyrimidine-2-yl)pro-pane] dihydrochloride, c) 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazoline-2-yl]propane}
dihydrochloride, and d) 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide].
After completed polymerization, the polymer gel was crumbled, dried at 120°C, and ground to the desired size fraction. A cross-linked copolymer resulted having a porous structure and entrapped nitrogen bubbles.
The screened size fraction 1000 to 2000 Nm was used for further examinations:
average particle density (dry): a) 1.49 g/cm3 b) 1.54 g/cm3 c) 1.51 g/cm3 d) 1.54 g/cm3 average particle density (swollen): a) 0.99 g/cm3 b) 0.99 g/cm3 c) 0.995 g/cm3 d) 0.995 g/cm3 floatability in tap water: a) 62% of particles after 1 h b) 58% of particles after 1 h c) 45% of particles after 1 h d) 32% of particles after 1 h Example 14 In a polymerization vessel, 256 g acrylic acid was placed first, di-luted with 335 g water and neutralized with 209 g sodium hydro-gencarbonate. Then, 1.8 g triallylamine was dissolved in the monomer solution, the monomer solution cooled to 10°C and blown out with nitrogen. After addition of the catalyst solutions (0.9 g sodium peroxidisulfate, 0.2 g hydrogen peroxide (35%), and 0.01 g ascorbic acid) and 8.8 g 4,4'-azobis(4-cyanovaleric acid) used as blowing agent, the polymerization was started.
Within 7 minutes the maximum temperature of 103°C was reached. After polymerization, the polymer gel was crumbled, dried at 150°C and ground to the desired size fraction. A cross-linked acrylic acid homopolymer, partially as sodium salt, was ob-tained having a porous structure resulting from the entrapped ni-trogen bubbles.
The screened size fraction 850 to 2000 Nm was used for further examinations:
average particle density (dry): 1.70 g/cm3 average particle density (swollen): 0.99 g/cm3 floatability in tap water: 86% of particles after 1 h 80% of particles after 24 h floatability in 0.9% NaCI-solution: 65% of particles after 1 h floatability in sea-water: 60% of particles after 1 h Example 15 Under the same conditions as in Example 14 the polymerization was conducted using also 8.8 g blowing agent 4,4'-azobis(4-cya-novaleric acid), differing from Example 14, however, the acrylic acid monomer solution was neutralized with 310 g potassium hy-droxide solution. After completion of the polymerization, the poly-mer gel was crumbled, dried at 150°C, and ground to the desired size fraction. A cross-linked acrylic acid homopolymer, partially as potassium salt, was obtained having a porous structure and en-trapped nitrogen bubbles.
The screened size fraction 850 to 2000 Nm was used for further examinations:
average particle density (dry): 1.63 g/cm3 average particle density (swollen): 0.97 g/cm3 floatability in tap water: 100% of particles after 1 h 96% of particles after 24 h floatability in 0.9% NaCI-solution: 95% of particles after 1 h floatability in sea-water: 80% of particles after 1 h Examples 16 to 21 256 g acrylic acid was placed in a polymerization vessel first, di-luted with 335 g water and neutralized with 200 g sodium hydrox-ide solution (50%). Then, 0.77 g triallylamine was dissolved in the monomer solution, the monomer solution cooled to 10°C, blown out with nitrogen, and the polymerization started with the same catalyst system as in Example 14. The following table 1 shows the added amounts of 2,2'-azobis(2-methylpropionamidine)dihydro-chloride (ABAH) and 4,4'-azobis(4-cyanovaleric acid) (ABCVA).
The maximum temperatures of 100 to 102°C were achieved within 7 to 12 minutes. After completion of the polymerization, ~ 179 775 the polymer gels were crumbled, dried at 150°C and ground to the desired size fraction. The thus produced cross-linked acrylic acid homopolymers, partially as sodium salts, have a porous structure which was achieved by the entrapped nitrogen bubbles.
For comparison purposes, another polymer with only 0.08%-wt.
of ABAH was prepared which could not have a porous structure owing to the small amount of ABAH which completely decomposed during polymerization.
The screened size fractions 150 to 850 Nm were then used to de-termine the absorption rate and the absorption capacity according to the tea bag test.
The liquid absorption of 0.2 g test substance was determined gravimetrically in a tea bag after 15, 60, and 600 seconds. The retention value was also determined gravimetrically after centrifug-ing in a centrifuge, e.g. in a commercial spin dryer, at 1400 rpm, the value was then expressed in terms of 1 g of product. 0.9%
NaCI-solution was used as test liquid.
Table 1: Dependence of absorption rate and absorption capacity on the added ABAH or ABCVA amounts AdditiveAdded Tea bag Tea bag Tea bag amount 15 sec. 60 sec. Retention (%-wt.) (g/g) (g/g) (g/g) Example 16 ABAH 0.28 10.5 21.1 34.3 Example 17 ABAH 0.58 12.4 25.8 38.8 Example 18 ABAH 1.08 18.2 34.4 40.2 Example 19 ABCVA 0.2 10.2 16.7 32.9 Example 20 ABCVA 0.5 9.7 17.6 36.7 Example 21 ABCVA 1.0 10.1 27.7 41 .0 Comparison ABAH 0.08 8.1 13.1 33.6
Claims (30)
1. Water-swellable, cross-linked, particulate polymers based on acrylic acid and its derivatives and having a porous structure, a high absorption capacity, and a high absorption rate for water and/or liquids, characterized in that the porous structure is formed by nitrogen dispersed in the polymer and that the polymer particles cles in dry condition have a density of above 1.0 g/cm3 and in swollen condition have a density of below 1.0 g/cm5.
2. The water-swellable, cross-linked, particulate polymers according to claim 1 characterized in that the polymer particles in swollen condition have an average particle density of 0.900 to 0.999 g/cm3 and that the particle-size distribution of the particles is in a range of 0.1 to 5 mm.
3. The water-swellable, cross-linked, particulate polymers according to claim 2 characterized in that the particle-size distribution is in a range of 0.8 to 3 mm.
4. The water-swellable, cross-linked, particulate polymers according to any one of claims 1 to 3 characterized in that they are built up of at least one of the following monomers:
acrylic acid, methacrylic acid, acrylamidopropane sulfonic acid, acrylamidomethylpropane sulfonic acid, the alkali, alkaline-earth, and ammonium salts of the above acids, as well as of acrylamide and methacrylamide.
acrylic acid, methacrylic acid, acrylamidopropane sulfonic acid, acrylamidomethylpropane sulfonic acid, the alkali, alkaline-earth, and ammonium salts of the above acids, as well as of acrylamide and methacrylamide.
5. The water-swellable, cross-linked, particulate polymers according to any one of claims 1 to 4 characterized in that they are built up as copolymers of at least one of the monomers according to claim 4 and at least one of the following monomers: acrylonitrile, methacrylonitrile, vinyl pyrrolidone, a water-soluble polymerizable acid and its salt, a hydroxy group-containing ester of a polymerizable acid, an amino group-containing and ammonium group-containing ester and amide of a polymerizable acid, and optionally other monomers partially soluble in water in portions of up to 20%-wt., relative to the total monomer quantity, and of at least one cross-linking di- or polyfunctional monomer, and optionally a graft polymer of the mentioned monomers with oligosaccharides and/or polysaccharides and/or polyvinyl alcohol.
6. The water-swellable, cross-linked, particulate polymers according to claim 5 characterized in that they are built up of malefic acid, fumaric acid, itaconic acid, and/or vinyl sulfonic acid as water-soluble polymerizable acid.
7. The water-swellable, cross-linked, particulate polymers according to claim 5 characterized in that they are built up of a hydroxy-ethyl- and hydroxypropyl ester of acrylic acid and/or methacrylic acid as hydroxy group-containing ester of a polymerizable acid.
8. The water-swellable, cross-linked, particulate polymers according to claim 5 characterized in that they are built up of a dialkyl aminoester of a polymerizable acid.
9. The water-swellable, cross-linked, particulate polymers according to claim 8 characterized in that they are built up of a dimethyland diethylaminoalkyl ester of acrylic acid and/or methacrylic acid.
10. The water-swellable, cross-linked, particulate polymers according to claim 5 characterized in that they are built up of a trimethyl- and triethylammonium alkylester of acrylic acid and/or methacrylic acid and a corresponding amide.
11. The water-swellable, cross-linked, particulate polymers according to any one of claims 5 to 10 characterized in that they comprise portions of the monomers which are partially soluble in water of up to 10%-wt.
12. The water-swellable, cross-linked, particulate polymers according to any one of claims 1 to 11 characterized in that they are built up of 80 to 100%-wt., relative to the total monomers, of water-soluble monomers and of 0 to 20%-wt. of monomers which are only partially soluble or insoluble in water.
13. The water-swellable, cross-linked, particulate polymers according to claim 12 characterized in that they are built up as partially water-soluble or water-insoluble monomers of vinyl acetate, esters of acrylic and/or methacrylic acid having C1 to C10-alcohols, styrene, and/or alkylated styrenes.
14. A process for the production of water-swellable, cross-linked, particulate polymers having a porous structure and a high absorption rate for water and/or aqueous liquids by polymerization of water-soluble monomers and optionally only partially water-soluble or water-insoluble monomers in amounts of up to 20%-wt., relative to the total monomer quantity, in the presence of at least one cross-linking di- or polyfunctional monomer, as well as optional oligosaccharides and/or polysaccharides and/or polyvinyl alcohol as graft basis, characterized in that the aqueous monomer solution comprises as polymerization initiator and blowing agent one or several azo compounds having a half-time of at least 10 hours at a temperature of 30 to 120°C, with the concentration of polymerization initiator and blowing agent, relative to the total monomer solution, amounting to 0.1 to 5.0%-wt., and that the polymer gel is crumbled, dried at 100 to 240°C, and ground, and that the polymer powder is classified by screening.
15. The process for the production of water-swellable, cross-linked, particulate polymers according to claim 14 characterized in that the only partially water-soluble monomers to be polymerized are used in amounts of up to 10%-wt., relative to the total monomer quantity.
16. The process for the production of water-swellable, cross-linked, particulate polymers according to any one of claims 14 to 15 characterized in that the concentration of polymer initiator and blowing agent amounts to 0.2 to 2.0%-wt., relative to the total monomer solution.
17. The process for the production of water-swellable, cross-linked, particulate polymers according to claim 14 characterized in that the polymer gel is dried at 120 to 180°C.
18. The process for the production of water-swellable, cross-linked, particulate polymers according to any one of claims 14 to 17 characterized in that 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 4,4'-azobis(4-cyanovaleric acid), or 2,2'-azobis[2-(4,5,6,7-tetrahydro-1H-diazepine-2-yl)propane] dihydrochloride alone or in admixture with other azo compounds are used as polymerization initiator and blowing agent.
19. The process for the production of water-swellable, cross-linked, particulate polymers according to claims 14 to 18 characterized in that the polymerization is conducted such that a temperature in the polymer gel of at least 100°C is achieved.
20. The process for the production of water-swellable, cross-linked, particulate polymers according to claim 19 characterized in that the polymerization is conducted such that a temperature in the polymer gel of 110 to 120°C is achieved.
21. The use of the polymers according to claims 1 to 13 in products for the absorption and/or retention of water and/or aqueous liquids as well as for applications in the medical field.
22. The use of the polymers according to claim 21 in products for the absorption and/or retention of body fluids.
23. The use of the polymers according to claims 21 to 22 in products for the absorption and/or retention of urine or blood.
24. The use of the polymers according to claims 21 to 23 in products in absorbent disposable articles for hygienic purposes.
25. The use of the polymers according to claim 24 in products in diapers, incontinence pads, sanitary napkins, and tampons.
26. The use of the polymers according to claims 1 to 13 for the absorption and/or retention of water and/or an aqueous liquid comprising at least one active substance, and for the subsequent release of water and/or an active substance solution to a surrounding medium, with fertilizers, plant protection agents, microbicidal substances, herbicides, insecticides, nematocides, pharmaceutic and cosmetic active substances, dyes, illuminants, and perfuming agents being used as active substances.
27. The use of the polymers according to claim 26 for the release of fertilizers or plant protection agents to soils or water for plant cultures.
28. The use of the polymers according to claims 1 to 13 for the release of insecticides for insect control.
29. The use of the polymers according to claim 28 to control mosquito larvae on large bodies of water.
30. The use of the polymers according to claims 1 to 13 in absorbent articles characterized in that the absorbent articles are crumbled mechanically and placed into water or aqueous liquids, and that the polymer particles are separated in swollen stage.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4344224.2 | 1993-12-23 | ||
| DE4344224A DE4344224A1 (en) | 1993-12-23 | 1993-12-23 | Crosslinked synthetic polymers with porous structure, high absorption rate for water, aqueous solutions and body fluids, a process for their preparation and their use for the absorption and / or retention of water and / or aqueous liquids |
| PCT/EP1994/004221 WO1995017455A1 (en) | 1993-12-23 | 1994-12-19 | Cross-linked polymers with a porous structure, high absorbency rate for water, aqueous solutions and bodily fluids, process for producing them and their use for absorbing and/or retaining water and/or aqueous liquids |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2179775A1 CA2179775A1 (en) | 1995-06-29 |
| CA2179775C true CA2179775C (en) | 2000-03-28 |
Family
ID=6506046
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002179775A Expired - Fee Related CA2179775C (en) | 1993-12-23 | 1994-12-19 | Cross-linked polymers with a porous structure |
Country Status (14)
| Country | Link |
|---|---|
| US (1) | US5856370A (en) |
| EP (1) | EP0736060B2 (en) |
| JP (1) | JPH09507085A (en) |
| AT (1) | ATE156163T1 (en) |
| BR (1) | BR9408391A (en) |
| CA (1) | CA2179775C (en) |
| CZ (1) | CZ175996A3 (en) |
| DE (2) | DE4344224A1 (en) |
| ES (1) | ES2107299T5 (en) |
| PL (1) | PL316236A1 (en) |
| SK (1) | SK281691B6 (en) |
| TW (1) | TW301656B (en) |
| WO (1) | WO1995017455A1 (en) |
| ZA (1) | ZA9410200B (en) |
Families Citing this family (64)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996017884A1 (en) * | 1994-12-08 | 1996-06-13 | Nippon Shokubai Co., Ltd. | Water-absorbent resin, process for production thereof, and water-absorbent resin composition |
| JP2007314794A (en) * | 1994-12-08 | 2007-12-06 | Nippon Shokubai Co Ltd | Water-absorbing resin composition, and water-absorbing article containing the same and preparation process of water-absorbing resin |
| DE19646484C2 (en) * | 1995-11-21 | 2000-10-19 | Stockhausen Chem Fab Gmbh | Liquid absorbing polymers, processes for their production and their use |
| US6107358A (en) * | 1996-08-23 | 2000-08-22 | Nippon Shokubai Co., Ltd. | Water-absorbent resin and method for production thereof |
| TW474961B (en) * | 1996-10-14 | 2002-02-01 | Nippon Catalytic Chem Ind | Water-swelling crosslinked polymer, production process thereof, and measurement method for pore volume of swollen crosslinked polymer |
| ATE243012T1 (en) | 1997-04-18 | 2003-07-15 | Procter & Gamble | USE OF HYDROGEL-FORMING POLYMERS IN ABSORBENT MATERIALS FOR ABSORBING BODY FLUID |
| DE19752128A1 (en) * | 1997-11-25 | 1999-07-29 | Stockhausen Chem Fab Gmbh | Process for the preparation of water-soluble or water-swellable polymers with a very low residual monomer content, products produced thereafter and their use |
| DE19936223A1 (en) * | 1999-08-05 | 2001-02-22 | Stockhausen Chem Fab Gmbh | Composition containing the active ingredient and its production and use |
| US6271281B1 (en) | 1999-08-26 | 2001-08-07 | Medennium, Inc. | Homopolymers containing stable elasticity inducing crosslinkers and ocular implants made therefrom |
| US6131331A (en) * | 1999-09-01 | 2000-10-17 | Naturally Safe Technologies, Inc. | Composition and method of enhancing moisture content of tree and plants |
| US6890888B2 (en) * | 2000-07-03 | 2005-05-10 | Nft Industries, Llc | Controlled release agricultural products and processes for making same |
| JP2002053405A (en) * | 2000-08-08 | 2002-02-19 | Aventis Cropscience Gmbh | Agrochemical preparation floating on water surface |
| EP1291368B1 (en) | 2001-04-16 | 2017-05-31 | Sumitomo Seika Chemicals Co., Ltd. | Water-absorbing resin suitable for absorbing viscous liquid containing high-molecular compound, and absorbent and absorbent article each comprising the same |
| US20020176964A1 (en) * | 2001-05-24 | 2002-11-28 | Koslow Technologies Corp. | Rapid absorbent structures |
| DE10148570A1 (en) * | 2001-10-01 | 2003-04-10 | Goldschmidt Ag Th | Composition containing fungus and polymeric additive, useful for controlling pests, e.g. insects on plants, has increased activity and stability |
| DE10157350A1 (en) * | 2001-11-22 | 2003-05-28 | Stockhausen Chem Fab Gmbh | Production of controlled release plant treatment composition, comprises kneading water-absorbing polymer containing absorbed water with active agent, e.g. fungicide or insecticide |
| US6861477B2 (en) * | 2001-12-21 | 2005-03-01 | Kimberly-Clark Worldwide, Inc. | Microphase separated superabsorbent compositions and method for making |
| WO2004031253A1 (en) * | 2002-10-02 | 2004-04-15 | Coloplast A/S | A hydrogel |
| DE10253255A1 (en) * | 2002-11-15 | 2004-06-03 | Air & D - Sarl | Pesticide Formulation |
| EP1682194B2 (en) * | 2003-10-31 | 2017-03-29 | Basf Se | Blood- and/or body fluid-absorbing polymer particles |
| US7425595B2 (en) * | 2003-12-15 | 2008-09-16 | Absorbent Technologies, Inc. | Superabsorbent polymer products including a beneficial additive and methods of making and application |
| PT1737907T (en) * | 2003-12-15 | 2019-05-29 | Vjs Investments Ltd | A superabsorbent polymer product including a bioactive, growth-promoting additive |
| US7354980B1 (en) | 2004-03-12 | 2008-04-08 | Key Medical Technologies, Inc. | High refractive index polymers for ophthalmic applications |
| US8598405B2 (en) | 2004-05-12 | 2013-12-03 | Nippon Shokubai Co., Ltd. | Waste solution solidifying agent, process for preparing the same and use of the same |
| JP2006061249A (en) * | 2004-08-25 | 2006-03-09 | Nippon Shokubai Co Ltd | Ashtray having fire extinguishing action, and gel for fire extinguishment |
| AU2005280088A1 (en) * | 2004-08-27 | 2006-03-09 | Absorbent Technologies, Inc. | Superabsorbent polymers in agricultural applications |
| US7446157B2 (en) | 2004-12-07 | 2008-11-04 | Key Medical Technologies, Inc. | Nanohybrid polymers for ophthalmic applications |
| CN100344654C (en) * | 2005-07-14 | 2007-10-24 | 中国科学院长春应用化学研究所 | Method for preparing water soluble polymer material |
| US7607259B2 (en) * | 2006-01-17 | 2009-10-27 | Absorbent Technologies, Inc. | Superabsorbent polymer root dip |
| US20070167330A1 (en) * | 2006-01-17 | 2007-07-19 | Savich Milan H | Superabsorbent polymer applicator |
| US20070163172A1 (en) * | 2006-01-17 | 2007-07-19 | Savich Milan H | Biodegradable mat containing superabsorbent polymers |
| EP3015119A1 (en) * | 2006-10-30 | 2016-05-04 | Novartis AG | Method for applying a coating onto a silicone hydrogel lens |
| EP2592097A1 (en) * | 2007-12-21 | 2013-05-15 | S.P.C.M. Sa | Polymeric thickener composition |
| JP5600670B2 (en) | 2009-02-17 | 2014-10-01 | 株式会社日本触媒 | Polyacrylic acid water-absorbing resin powder and method for producing the same |
| US9957341B2 (en) | 2009-06-09 | 2018-05-01 | William Chambers | Biodegradable absorbent material and method of manufacture |
| WO2010144575A1 (en) * | 2009-06-09 | 2010-12-16 | William Chambers | Biodegradable absorbent material and method of manufacture |
| US8481159B2 (en) * | 2009-09-04 | 2013-07-09 | Basf Se | Water-absorbent porous polymer particles having specific sphericity and high bulk density |
| CN102498135B (en) | 2009-09-16 | 2014-02-19 | 株式会社日本触媒 | Method for producing water absorbent resin powder |
| CN102712712B (en) | 2009-12-24 | 2015-05-06 | 株式会社日本触媒 | Water-absorbable polyacrylic acid resin powder, and process for production thereof |
| EP2557095B1 (en) | 2010-04-07 | 2016-10-05 | Nippon Shokubai Co., Ltd. | Method for producing water absorbent polyacrylic acid (salt) resin powder, and water absorbent polyacrylic acid (salt) resin powder |
| JP5616437B2 (en) | 2010-04-27 | 2014-10-29 | 株式会社日本触媒 | Method for producing polyacrylic acid (salt) water-absorbing resin powder |
| US9074030B2 (en) | 2010-06-30 | 2015-07-07 | Nippon Shokubai Co., Ltd. | Polyacrylic acid-type water absorbent resin and method for producing same |
| US9596801B2 (en) | 2010-10-25 | 2017-03-21 | Vjs Investments Limited | Superabsorbent polymer seed coatings and associated methods |
| EP2669318B1 (en) | 2011-01-28 | 2020-06-17 | Nippon Shokubai Co., Ltd. | Manufacturing method for polyacrylic acid (salt) -based water-absorbent resin powder |
| EP2727953B1 (en) | 2011-06-29 | 2017-03-08 | Nippon Shokubai Co., Ltd. | Polyacrylic acid (salt) water-absorbent resin powder, and method for producing same |
| CN104703691B (en) | 2012-10-03 | 2018-03-02 | 株式会社日本触媒 | Water absorbing agent and its manufacture method |
| EP4159307A1 (en) | 2013-09-30 | 2023-04-05 | Nippon Shokubai Co., Ltd. | Method for filling particulate water absorbing agent and method for sampling filled particulate water absorbing agent |
| WO2015093594A1 (en) | 2013-12-20 | 2015-06-25 | 株式会社日本触媒 | Polyacrylic acid (salt) water absorbent, and method for producing same |
| CN106029220B (en) | 2014-02-28 | 2020-08-18 | 株式会社日本触媒 | Poly (meth) acrylic acid (salt) particulate water absorbing agent and method for producing same |
| US9896529B2 (en) | 2014-03-03 | 2018-02-20 | Nippon Shokubai Co., Ltd. | Method for producing polyacrylic acid (salt)-based water-absorbable resin |
| KR101769100B1 (en) | 2014-11-27 | 2017-08-30 | 주식회사 엘지화학 | Super absorbent polymer with fast absorption rate under load and preparation method thereof |
| WO2016105039A1 (en) * | 2014-12-26 | 2016-06-30 | 삼성전자 주식회사 | Polymer gel and preparation method therefor |
| JP6577709B2 (en) | 2014-12-26 | 2019-09-18 | 三星電子株式会社Ｓａｍｓｕｎｇ Ｅｌｅｃｔｒｏｎｉｃｓ Ｃｏ．，Ｌｔｄ． | Gel production method and acoustic coupler gel |
| CN104710568A (en) * | 2015-04-01 | 2015-06-17 | 西安石油大学 | Preparation method of retarding swelling anti-salt viscoelastic particle profile control agent |
| JP6666673B2 (en) | 2015-09-07 | 2020-03-18 | キリンホールディングス株式会社 | Intracellular delivery vehicle |
| CN105294919A (en) * | 2015-12-08 | 2016-02-03 | 中蓝晨光化工研究设计院有限公司 | Post-crosslinking super absorbent resin and preparation method thereof |
| KR101949996B1 (en) | 2016-01-28 | 2019-02-19 | 주식회사 엘지화학 | Preparation method for super absorbent polymer |
| RU2643040C2 (en) * | 2016-03-21 | 2018-01-30 | федеральное государственное бюджетное образовательное учреждение высшего образования "Воронежский государственный университет" (ФГБОУ ВО "ВГУ") | Method for obtaining water-absorbing composite polymer material |
| KR102086058B1 (en) | 2017-01-24 | 2020-03-06 | 주식회사 엘지화학 | Preparation method of super absorbent polymer |
| KR102418916B1 (en) | 2017-09-05 | 2022-07-07 | 주식회사 엘지화학 | Super absorbent polymer |
| CN110841685B (en) * | 2019-11-26 | 2022-07-01 | 天津工业大学 | Ag-containing water surface floating3PO4And carboxylated g-C3N4Preparation method of hydrogel photocatalytic film |
| CN112500530B (en) * | 2020-10-30 | 2022-05-31 | 广西大学 | Calcium carbonate/bagasse cellulose-based super absorbent resin and preparation method thereof |
| CN113372611B (en) * | 2021-06-07 | 2023-12-29 | 万华化学集团股份有限公司 | Super-absorbent polymer capable of improving absorption speed and preparation method and application thereof |
| CN113461863B (en) * | 2021-07-27 | 2023-12-01 | 天津工业大学 | Polymer water-absorbent resin and preparation method and application thereof |
Family Cites Families (36)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1273251B (en) * | 1966-06-02 | 1968-07-18 | Georg Langhoff | Process for the sustainable fertilization of plants |
| US3544490A (en) * | 1967-01-04 | 1970-12-01 | Gulf Research Development Co | Ethylene polymer foam compositions and process for making same |
| US3649614A (en) * | 1968-08-15 | 1972-03-14 | Pennwalt Corp | Polyazo sequential free radical initiators |
| DE2029296A1 (en) * | 1970-06-13 | 1971-12-23 | Bayer | (meth)acrylic foams - polymerised and foamed in one operation by heating the monomer in presence of urotropine |
| US3993609A (en) * | 1974-03-21 | 1976-11-23 | Pennwalt Corporation | Process for preparing foamed structures |
| JPS5355260A (en) * | 1976-10-26 | 1978-05-19 | Kao Corp | Absorber |
| JPS55104247A (en) * | 1979-02-06 | 1980-08-09 | Sumitomo Chem Co Ltd | Improved preparation of azo compound |
| GR75732B (en) * | 1980-08-25 | 1984-08-02 | Johnson & Johnson | |
| JPH0229085B2 (en) † | 1982-07-21 | 1990-06-27 | Arakawa Chem Ind | KANSOSHITAKYUSUISEIJUSHINOSEIZOHOHO |
| JPS5871907A (en) † | 1981-10-26 | 1983-04-28 | Arakawa Chem Ind Co Ltd | Manufacture of dry absorptive resin solid |
| US4525527A (en) † | 1982-01-25 | 1985-06-25 | American Colloid Company | Production process for highly water absorbable polymer |
| JPS60163956A (en) * | 1984-02-04 | 1985-08-26 | Arakawa Chem Ind Co Ltd | Production of water-absorptive resin |
| JPS6173704A (en) * | 1984-09-19 | 1986-04-15 | Arakawa Chem Ind Co Ltd | Production of highly water-absorptive resin |
| DE3505920A1 (en) * | 1985-02-21 | 1986-08-21 | Röhm GmbH, 6100 Darmstadt | SLOWLY CROSSLINKED, PARTICULAR, SOLID POLYMERISATES OR MIXED POLYMERS, QUICKLY SWELLING IN WATER, PROCESS FOR THEIR PRODUCTION AND THEIR USE IN HYGIENE ITEMS |
| JPS61271303A (en) * | 1985-05-24 | 1986-12-01 | Lion Corp | Production of water-absorptive resin |
| SU1353783A1 (en) * | 1985-07-22 | 1987-11-23 | Предприятие П/Я А-3832 | Promoter of foaming rubber mixes on base of carbochain rubbers |
| US4742086A (en) † | 1985-11-02 | 1988-05-03 | Lion Corporation | Process for manufacturing porous polymer |
| US4751250A (en) * | 1986-05-14 | 1988-06-14 | Mobay Corporation | Process for foaming thermoplastic |
| JPS6356511A (en) * | 1986-08-27 | 1988-03-11 | Osaka Yuki Kagaku Kogyo Kk | Production of resin having high water absorption property |
| US4818534A (en) * | 1987-04-01 | 1989-04-04 | Lee County Mosquito Control District | Insecticidal delivery compositions and methods for controlling a population of insects in an aquatic environment |
| US4983390A (en) * | 1987-04-01 | 1991-01-08 | Lee County Mosquito Control District | Terrestrial delivery compositions and methods for controlling insect and habitat-associated pest populations in terrestrial environments |
| WO1988009801A1 (en) * | 1987-06-01 | 1988-12-15 | The Dow Chemical Company | Foamed polymeric materials and method for preparing the same |
| KR0130652B1 (en) † | 1987-08-14 | 1998-04-07 | 존 휴즈 | Improved process for preparing water-absorbing resins |
| IT1226741B (en) † | 1987-08-19 | 1991-02-05 | Procter & Gamble | ABSORBENT STRUCTURES WITH GELIFYING AGENT AND ABSORBENT ITEMS CONTAINING SUCH STRUCTURES. |
| IL88245A0 (en) * | 1987-11-13 | 1989-06-30 | Fraunhofer Ges Forschung | Process for the production of rigid foam comprising acrylic and/or methacrylic polymers without using fluorocarbons as a foaming agent |
| DE3837555A1 (en) * | 1987-11-13 | 1989-06-01 | Fraunhofer Ges Forschung | Process for the production of rigid foam from acrylic and/or methacrylic polymers without using fluorocarbons as blowing agent |
| DE3837530A1 (en) * | 1987-11-13 | 1989-05-24 | Fraunhofer Ges Forschung | Process for the production of rigid foam from acrylic and methacrylic polymers |
| JP2548302B2 (en) † | 1988-05-31 | 1996-10-30 | 三菱化学株式会社 | Water absorbent resin having little volume expansion and method for producing the same |
| KR970009239B1 (en) † | 1988-06-16 | 1997-06-09 | 미츠비시유카 가부시키가이샤 | Process for producing highly water absorptive polymer |
| AT391321B (en) * | 1988-08-29 | 1990-09-25 | Chemie Linz Gmbh | METHOD FOR PRODUCING LIQUID-ABSORBING ACRYLIC RESINS |
| US4918110A (en) * | 1988-09-12 | 1990-04-17 | Hexcel Corporation | Compositions and process for producing foam plastics |
| US5214075A (en) * | 1989-10-06 | 1993-05-25 | Cassella Aktiengesellschaft | Hydrophilic, swellable polymers |
| CA2039241A1 (en) * | 1990-04-18 | 1991-10-19 | Bi Le-Khac | Superabsorbent foam composition |
| AU656917B2 (en) * | 1990-10-09 | 1995-02-23 | Mcneil-Ppc, Inc. | Epoxy Resin Reaction Products |
| DE4123049A1 (en) * | 1991-07-12 | 1993-01-14 | Basf Ag | CROSSLINKED COPOLYMERISATE WITH CROSSLINKABLE GROUPS BASED ON ACRYLIC ACID OR METHACRYLIC ACID, METHOD FOR THE PRODUCTION THEREOF AND THEIR USE |
| US5429590A (en) * | 1992-12-01 | 1995-07-04 | Nitto Denko Corporation | Medical water-absorptive polymer and dressing for wound and medical bandage using the same |
-
1993
- 1993-12-23 DE DE4344224A patent/DE4344224A1/en not_active Withdrawn
-
1994
- 1994-12-13 TW TW083111583A patent/TW301656B/zh active
- 1994-12-19 WO PCT/EP1994/004221 patent/WO1995017455A1/en not_active Application Discontinuation
- 1994-12-19 PL PL94316236A patent/PL316236A1/en unknown
- 1994-12-19 CA CA002179775A patent/CA2179775C/en not_active Expired - Fee Related
- 1994-12-19 DE DE59403585T patent/DE59403585D1/en not_active Expired - Fee Related
- 1994-12-19 BR BR9408391A patent/BR9408391A/en not_active IP Right Cessation
- 1994-12-19 AT AT95903818T patent/ATE156163T1/en not_active IP Right Cessation
- 1994-12-19 ES ES95903818T patent/ES2107299T5/en not_active Expired - Lifetime
- 1994-12-19 EP EP95903818A patent/EP0736060B2/en not_active Expired - Lifetime
- 1994-12-19 CZ CZ961759A patent/CZ175996A3/en unknown
- 1994-12-19 US US08/663,117 patent/US5856370A/en not_active Expired - Fee Related
- 1994-12-19 SK SK802-96A patent/SK281691B6/en unknown
- 1994-12-19 JP JP7517175A patent/JPH09507085A/en not_active Ceased
- 1994-12-21 ZA ZA9410200A patent/ZA9410200B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| ES2107299T5 (en) | 2001-08-16 |
| ZA9410200B (en) | 1995-09-01 |
| PL316236A1 (en) | 1997-01-06 |
| TW301656B (en) | 1997-04-01 |
| ATE156163T1 (en) | 1997-08-15 |
| BR9408391A (en) | 1997-08-19 |
| EP0736060A1 (en) | 1996-10-09 |
| DE59403585D1 (en) | 1997-09-04 |
| CA2179775A1 (en) | 1995-06-29 |
| CZ175996A3 (en) | 1996-10-16 |
| SK80296A3 (en) | 1997-04-09 |
| DE4344224A1 (en) | 1995-06-29 |
| EP0736060B1 (en) | 1997-07-30 |
| ES2107299T3 (en) | 1997-11-16 |
| US5856370A (en) | 1999-01-05 |
| EP0736060B2 (en) | 2001-04-25 |
| JPH09507085A (en) | 1997-07-15 |
| WO1995017455A1 (en) | 1995-06-29 |
| SK281691B6 (en) | 2001-06-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2179775C (en) | Cross-linked polymers with a porous structure | |
| Po | Water-absorbent polymers: a patent survey | |
| US6660819B2 (en) | Method for producing synthetic polymerizates with a very low residual monomer content, products produced according to this method and the use thereof | |
| CA2166779C (en) | Powder-form cross-linked polymers capable of absorbing aqueous liquids and body fluids, method of preparing them and their use | |
| TWI441841B (en) | Water- soluble or water-swellable polymers, especially water- soluble or water-swellable copolymers of acrylamide and at least one ionic comonomer with low residual monomer content | |
| CN102369254B (en) | Method for blocking subterranean formations | |
| US6602950B1 (en) | Hydrophilic hydrogels with a high swelling capacity and method for producing and using them | |
| JP2002536471A (en) | Crosslinked hydrophilic, high swelling hydrogels, methods for their preparation and their use | |
| EP1374919B1 (en) | Water-Absorbent Resin and method for production thereof | |
| EP1091983B1 (en) | Water-absorbing polymers with supramolecular hollow molecules, method for producing them and use of the same | |
| US5672656A (en) | Temperature sensitive water absorbing and discharging polymer composition | |
| EP0574248A2 (en) | Method for production of absorbent resin and absorbent | |
| CN101511917A (en) | Polyamine coated superabsorbent polymers having transient hydrophobicity | |
| CN101511916A (en) | Polyamine-coated superabsorbent polymers | |
| MXPA04009844A (en) | Particulate water absorbent containing water absorbent resin as a main component. | |
| US7030199B1 (en) | Method for producing water-soluble or water-swellable polymerizates with a very low residual monomer content, products produced according to this method and the use thereof | |
| CN108178816A (en) | The manufacturing method of water-absorbing resins with high rate of liquid aspiration | |
| Meshram et al. | Super-absorbent polymer: a review on the characteristics and application | |
| JP2004315816A (en) | Producing method of water absorbing resin | |
| RU2643040C2 (en) | Method for obtaining water-absorbing composite polymer material | |
| KR101236345B1 (en) | Composition for treating excrement | |
| CN102311599B (en) | Method for preparing super absorbent resin | |
| TWI522410B (en) | Production efficiency of superabsorbent polymer | |
| TWI466933B (en) | Process for the production of a superabsorbent polymer | |
| CN115703868A (en) | Water-absorbent resin and method for producing same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |