CA2082506A1 - Cross-linked, water-absorbent polymer and its use in the production of hygiene items - Google Patents
Cross-linked, water-absorbent polymer and its use in the production of hygiene itemsInfo
- Publication number
- CA2082506A1 CA2082506A1 CA002082506A CA2082506A CA2082506A1 CA 2082506 A1 CA2082506 A1 CA 2082506A1 CA 002082506 A CA002082506 A CA 002082506A CA 2082506 A CA2082506 A CA 2082506A CA 2082506 A1 CA2082506 A1 CA 2082506A1
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- CA
- Canada
- Prior art keywords
- polymer
- water
- cross
- acid
- linked
- 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.)
- Abandoned
Links
Classifications
-
- 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
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
- A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
- A61L15/42—Use of materials characterised by their function or physical properties
- A61L15/60—Liquid-swellable gel-forming materials, e.g. super-absorbents
Abstract
A B S T R A C T
The invention relates to a cross-linked, water-absorb-ent polymer obtainable by the polymerization of a mix-ture consisting of a) 60-99%-wt. unsaturated, polymer-izable monomers with acid groups which are neutralized to the extent of at least 30 mol-%, b) 0-37%-wt. mono-mers copolymerizable with a), c) 0.1-3.0%-wt. of a cross-linking agent and d) 0-10%-wt. of a water-solu-ble polymer, in which polymerization is conducted with a redox catalyst system containing formamidine sulfin-ic acid as reducing agent. The polymer is distinguish-ed by a retention of greater than or equal to 23 g 0.9% aqueous NaCl-solution per 1 g of polymer, an ab-sorption of greater than or equal to 26 g 0.9% aque-ous NaCl-solution per 1 g of polymer at a load of 20 g/cm2 and a residual monomer content of less than 700 ppm, and preferably less than 500 ppm. The invention also relates to the use of this polymer in the pro-duction of hygiene articles.
The invention relates to a cross-linked, water-absorb-ent polymer obtainable by the polymerization of a mix-ture consisting of a) 60-99%-wt. unsaturated, polymer-izable monomers with acid groups which are neutralized to the extent of at least 30 mol-%, b) 0-37%-wt. mono-mers copolymerizable with a), c) 0.1-3.0%-wt. of a cross-linking agent and d) 0-10%-wt. of a water-solu-ble polymer, in which polymerization is conducted with a redox catalyst system containing formamidine sulfin-ic acid as reducing agent. The polymer is distinguish-ed by a retention of greater than or equal to 23 g 0.9% aqueous NaCl-solution per 1 g of polymer, an ab-sorption of greater than or equal to 26 g 0.9% aque-ous NaCl-solution per 1 g of polymer at a load of 20 g/cm2 and a residual monomer content of less than 700 ppm, and preferably less than 500 ppm. The invention also relates to the use of this polymer in the pro-duction of hygiene articles.
Description
A cross-linked, water-absorbing Polymer and its use in the production of hygiene items The present invention relates to a cross-linked poly-mer which absorbs aqueous liqu-ids; the polymer exhib-its improved properties with regard to swelling and its capability of retaining aqueous liquids under load and has a very low content of residual monomers and a high gel rigidity in swollen condition. The present invention further relates to the use of said polymers in the production of hygiene articles.
These water-absorbing polymers find a great variety of uses. For instance, they are employed in diapers, ar-ticles for adult incontinence, cable sheathings, cleaning clothes, or they are used in soil condition-ing.
These polymers are mainly used to absorb fluids which are produced or present within the body, in particular urine, and are therefore employed in diapers and adult incontinence articles. Up to the present, starch-acrylic-acid-graft-polymers and cross-linked acrylic-acid-salt-polymers have proved to be particularly suitable for this application, such as those known from U.S.-Patent No. 4,076,663 or EP [European Patent]
No. 0036463.
Whereas water-absorbing polymers with a very high swelling capacity on contact with liquids, also re-ferred to as the free swell capacity, were Preferred in the production of diapers in the past, polymers with completely different properties are required today.
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When it was realized that the water-absorbing polymers within the diaper are exDosed to mechanical load caused by movements of the person wearing the diaper, new requirements have been stipulated for the poly-mers, that is high retention, i.e., high capability of retaining aqueous liquids, and a high absorption of aqueous liquids under load. In addition - for toxico-logical reasons - the polymers shall exhibit a low residual monomer content and a low content of extract-able portions.
Since both concentration and kind of cross-linking agent as well as the polymerization catalysts strongly influence said four properties in water-absorbing pol-ymers, the production of a polymer exhibiting a high retention, a high absorption under load, a low content of residual monomers, and small amounts of extractable portions involves great difficulties.
While a high retention can only be achieved in a slightly cross-linked polymer, a high absorption under load requires a highly cross-linked, stable polymer which can swell against the external pressure only on the basis of this stability. However, with an increas-ing degree of cross-linkage, the content of residual monomers increases at the same time, since the diffu-sion of the remaining monomer molecules towards the reactive radical centers is reduced due to the rapidly increasing viscosity of the polymer gel during its production. An undesired decrease in retention or an increase in the extractable portions are frequently caused by catalyst systems which reduce the residual monomers or by an increased catalyst concentration.
The extractable portions of a crosslinked polymer are - . ~ . . . . ~ . , .
~ ~s~ 3 reduced with an increasing concentration of cross-linking agent.
EP No. 0083022 describes water-absorbent polymers hav-ing an extremely high free swell capacity and a low tendency to agglomerate. These polymers are produced by cross-linking the polymer particles with glycidyl ethers.
-U.S.-Patent No. 4,535,098 describes water-absorbing polymers with moieties of hydrophobic comonomers and an improved gel stability.
According to EP No. 0205674 absorbing polymers are produced by polymerization of the acrylic acid in its acid form and adjustment of the neutralization degree after termination of the polymerization. By this meth-od polymers are obtained which have less soluble por-tions and an improved gel stability. Depending on the degree of cross-linking the retention is in the range of 20 to 74 9 0.9~ NaCl-solution per 1 9 of polymer.
The excessive polymerization time and the expensive neutralization of the polymer gel are disadavantages of this method.
EP Nos. 0287970 and 0251314 describe UV- or electron irradiation~ respectively, to achieve low contents of residual monomers in water-absorbing polymers.
DE-OS 3738602 describes swellable, water-absorbing graft polymers obtained by radical polymerization of -preferably - acrylic acid. However, according to this patent, neither formamidine sulfinic acid is used to manufacture improved water-absorbing polymers nor is there any indication with respect to retention, ab-~. . -- .-.
. .
- ~
' ~
', " ' -h ''!i sorption under load, or residual monomer content of the described graft polymers.
DP 975794 describes the production of cation ex-changers from insoluble polymers of the (meth)acrylic acid or the salts thereof; the trimeric addition prod-uct of formaldehyde to acrylonitrile is used as cross-linking agent. The trimeric addition Product is NlN', N"-trisacryloyl-hexahydrotriazine. According to this patent, the polymerization can be carried out with redox systems consisting of persulfates and sulfoxy-reducing agents; formamidine sulfinic acid is men-tioned amongst others. Highly cross-linked polymers with low retention values are obtained. There are no indications with respect to conversion or residual monomer contents.
The known water-absorbent polymers do not provide the required property combination of high retention and high absorption under load, low content of residual monomers and small amounts of extractable portions.
It is accordingly the object of the present invention to provide a water-absorbing polymer exhibiting high retention and high absorption of aqueous liquids under load, as well as a low content of residual monomers and small amounts of extractable portions.
According to the present invention this object is achieved by a cross-linked, powdery polymer absorbing aqueous liquids or water, this polymer is obtained by polymerization of a mixture of a) 60.0 to 99.9~-wt. unsaturated, polymerizable mono-mers with acid groups which are neutralized to the ex-tent of at least 30 mol-~, .. ~
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b) 0 to 37%-~t. water-soluble monomers copolymerizable with a), c) 0.1 to 3.0%-wt. of a cross-linking agent, and d) 0 to 10%-wt. of a water-soluble polymer with water as aqueous solution, size reduction, drying, and grinding of the formed polymer, character-ized in that a multiply unsaturated monomer with at least one allylic unsaturated group or mixtures of polyvinyl and polyallyl compounds at a weight ratio of 1 : > 0.6 are used as cross-linking agent according to c), and that the polymerization is carried out using a redox system consisting of formamidine sulfinic acid and one or several organic peroxides.
These polymers exhibit a retention of greater than or equal to 28 9 0.9~ aqueous NaCl-solution per 1 9 of polymer, an absorption of greater than or equal to 26 9 0.9% NaCl-solution per 1 9 of polymer at a load of 20 g/cm2, and a residual monomer content of less than 700 ppm, preferably less than 500 ppm, and a content of extractable portions of less than 6%.
It is known to use formamidine sulfinic acid combined with peroxides to initiate the polymerization (cf.
Houben-Weyl, "Methoden der organischen Chemie", volume 14/1, page 265); however, surprisingly, it was found that the polymerization in the presence of the redox-catalyst-system formamidine sulfinic acid/peroxide re-sults in a very high conversion rate of the monomers into polymers und that the residual monomer content in the polymer amounts to-<700 ppm. In addition, it could not be foreseen that the retention of the water-. ~
- . . ~ ~ , :
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6 ~ s ., absorbent Dolymers is not deteriorated but - on the contrary - influenced positively, and that the poly-mers also exhibit a high absorption under load.
The water-absorbing polymer is composed by 60 to 99.9%-wt. of unsaturated, polymerizable monomers with acid groups, e.g., acrylic acid, methacrylic acid, 2-acrylamido 2-methylpropane sulfonic acid and mixtures of these monomers; the acid groups are neutralized to the extent of at least 30 mol-~, e.g., as salt of so-dium, potassium or ammonium.
The water-absorbing polymers may comprise as further monomers 0 to 37%-wt. of acrylamide, methacrylamide, hydroxyethyl acrylate, dimethylaminopropyl acrylate, dimethylaminopropyl acrylamide, or acrylamidopropyl trimethylammonium chloride. More than 37% of these monomers will deteriorate the swellability of the polymers.
.
The multiply unsaturated monomers with at least one allylic unsaturated group according to claim 1 are selected from the compound classes:
a) allyl esters, e.g., triallyl citrate, diallyl male-inate, allyl(meth)acrylate, b) polyallyl ethers, e.g., glycerol triallyl ether, polyalkylene glycol ether of the allyl glycidic ether, c) allyl amides, e.g., N,N'-diallyl succinic acid di-amide, N,N,N',N'-tetraallyl oxalic acid diamide, N-allyl acrylamide, N-diallyl(meth)acrylamide, or ~ ., . . . - . - . .
~, d) polyallyl amines~ e.g.. triallyl amine, tetraallyl ammonium chloride, methyl ~riallyl ammonium chloride, N,N'-tetraallyl ethylenediamine, N,N'-tetraallyl bu-tanediamine.
0 to 10%-wt. of partially or completely saponified polyvinyl alcohol, polyvinylpryrrolidone, starch or starch derivatives may be contained in the water-ab-sorbing polymer as water-soluble polymers. The molec-ular weight of these polymers is not critical as long as they are water-soluble.
The polymerization is carried out as solvent polymeri-zation either in batches or continuously. For this purpose, the monomers and the cross-linking agent are dissolved in water so that the monomer concentration of the polymerizing mixture amounts to 20 to 35%; the desired neutralization degree is adjusted by addition of a base, the neutralization degree shall amount to at least 30 mol-%. Wetting agents may optionally be added to the monomer solution.
The polymerization may also be carried out in the dis-perse state as inverse suspension or emulsion polymer-ization.
According to the present invention, the polymerization is carried out with a redox-catalyst-system comprising formamidine sulfinic acid as the reducing component and organic peroxides as oxidizing component. Cumene hydroperoxide and tertiary butyl hydroperoxide are preferred because of their water-solubility.
The formamidine sulfinic acid may also be formed in situ' from thiourea and hydrogen peroxide. 'In situ , . .
., ~
is to be understood in such a way that thiourea and hydrogen peroxide instead of formamidine sulfinic acid are added to the monomer solution and that the thio-urea is oxidized in the monomer solution to form form-amidine sulfinic acid.
The amount of the redox catalyst is in the usual range and amounts to about 100 to 2000 ppm formamidine sul-finic acid, relative to monomer solution, and to 100 to 4000 ppm peroxide.
In addition to formamidine sulfinic acid a second reducing agent may be used in an amount of up to 10%-wt., relative to formamidine sulfinic acid, examples thereof include ascorbic acid, sulfite, dihydroxy-maleic acid, or hydroxylamine.
Azo compounds, such as azo bisamidinopropane-hydro-chloride, may be used as further components of the polymerization catalysis.
The polymerization may be initiated by the formamidine sulfinic acid or by its alkali salts, or by means of a co-reducing agent or UV-light.
After polymerization, the polymer gel is reduced in size, dried, and screened to the desired particle size.
For the purpose of characterizing the water-absorbing polymers, the Polymer powder is screened out to lO0-850 ~m, and this fraction is then optionally mixed with 0.1 to 1.0~ of a fumed silica, preferably with 0.5~ Aerosil 200; subsequently, retention, absorption ~ . .
- , .: : :
, . ~, , :~ : ~. :, .
:- : :' - ~ ' -:
under load, and content or residual monomers and ex-tractable proportions are measured.
The retention is determined according to the tea bag test method and reported as avera3e value of three measurements: approximately 200 mg polymer are en-closed in a tea bag and immersed in 0.9% aqueous NaCl-solution for 10 minutes. Then the tea bag is centri-fuged at 1400 rpm in a centrifuge for 5 minutes and weighed. One tea bag without water-absorbing polymer is used as blank.
Weignt - blank reading Retention = (9/9 Initial weight The absorption under load was determined with a Demand-Absorbency testing device (cf. `'Allgemeiner Flie~stoff-Report" 5~82, page 210-218), the test desk was substituted for a Buchner funnel. The Buchner fun-nel is 6.0 cm in diameter and adjusted such that the fluid level is on the level of the ceramic filter plate. A surface-ground cylinder having a diameter of 5.9 cm is used as punch the weight of ~hich exerts a pressure of 20 g/cm2.
For measuring purposes round filter paper is placed in the Buchner-funnel and 0.85 9 of water-absorbing poly-mer of the size fraction 300 to 600 ~m is evenly sprinkled thereon. Subsequently, the cylinder is in-serted and the liquid stopping device opened. 0.9%
aqueous NaCl-solution is used as test liquid. After one hour, the liquid absorption is read from the burette as consumption.
The residual monomer content in the water-absorbing polymers is determined by HPLC. To determine the sol-uble portion, the water-absorbing resin is stirred in 0.9% NaCl-solution for one hour, then it was filtered and the content of acid groups measured in the fil-trate.
Example 1:
-An aqueous acrylic acid solution comprising 0.5% di-allyl acrylamide, relative to acrylic acid, was neu-tralized with sodium hydroxide solution under cooling.
The acrylic acid concentration of the monomer solution amounted to 30%, the neutralization degree to 70%. 850 g of the monomer solution was cooled to 10C and purged with nitrogen for 10 minutes. Subsequently, 3 9 tertiary butyl hydroperoxide, 4.5 mg ascorbic acid, dissolved in 10 9 water, and 500 mg formamidine sul-finic acid, dissolved in 20 9 water, was added. Poly-merization started immediately, this could be recog-nized by a temperature elevation of the monomer solu-tion. After 30 minutes, the obtained polymer gel block was crumbled and dried in hot air at 150C.
Subsequently, the polymer was ground, screened out to 100 to 850 ~m and mixed with 0.5% Aerosil 200. Ihe wa-ter-absorbing polymer exhibited the following proper-ties:
Retention: 29 9/9 Absorption under load: 27 9/9 Content of resid. monomers: 255 ppm Extractable por-tion: 4.9%
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Ex mple 2.
These water-absorbing polymers find a great variety of uses. For instance, they are employed in diapers, ar-ticles for adult incontinence, cable sheathings, cleaning clothes, or they are used in soil condition-ing.
These polymers are mainly used to absorb fluids which are produced or present within the body, in particular urine, and are therefore employed in diapers and adult incontinence articles. Up to the present, starch-acrylic-acid-graft-polymers and cross-linked acrylic-acid-salt-polymers have proved to be particularly suitable for this application, such as those known from U.S.-Patent No. 4,076,663 or EP [European Patent]
No. 0036463.
Whereas water-absorbing polymers with a very high swelling capacity on contact with liquids, also re-ferred to as the free swell capacity, were Preferred in the production of diapers in the past, polymers with completely different properties are required today.
, . - ~ ~ ,-" ' ~ . ' .
. .
, - - : .
? ~ r~
When it was realized that the water-absorbing polymers within the diaper are exDosed to mechanical load caused by movements of the person wearing the diaper, new requirements have been stipulated for the poly-mers, that is high retention, i.e., high capability of retaining aqueous liquids, and a high absorption of aqueous liquids under load. In addition - for toxico-logical reasons - the polymers shall exhibit a low residual monomer content and a low content of extract-able portions.
Since both concentration and kind of cross-linking agent as well as the polymerization catalysts strongly influence said four properties in water-absorbing pol-ymers, the production of a polymer exhibiting a high retention, a high absorption under load, a low content of residual monomers, and small amounts of extractable portions involves great difficulties.
While a high retention can only be achieved in a slightly cross-linked polymer, a high absorption under load requires a highly cross-linked, stable polymer which can swell against the external pressure only on the basis of this stability. However, with an increas-ing degree of cross-linkage, the content of residual monomers increases at the same time, since the diffu-sion of the remaining monomer molecules towards the reactive radical centers is reduced due to the rapidly increasing viscosity of the polymer gel during its production. An undesired decrease in retention or an increase in the extractable portions are frequently caused by catalyst systems which reduce the residual monomers or by an increased catalyst concentration.
The extractable portions of a crosslinked polymer are - . ~ . . . . ~ . , .
~ ~s~ 3 reduced with an increasing concentration of cross-linking agent.
EP No. 0083022 describes water-absorbent polymers hav-ing an extremely high free swell capacity and a low tendency to agglomerate. These polymers are produced by cross-linking the polymer particles with glycidyl ethers.
-U.S.-Patent No. 4,535,098 describes water-absorbing polymers with moieties of hydrophobic comonomers and an improved gel stability.
According to EP No. 0205674 absorbing polymers are produced by polymerization of the acrylic acid in its acid form and adjustment of the neutralization degree after termination of the polymerization. By this meth-od polymers are obtained which have less soluble por-tions and an improved gel stability. Depending on the degree of cross-linking the retention is in the range of 20 to 74 9 0.9~ NaCl-solution per 1 9 of polymer.
The excessive polymerization time and the expensive neutralization of the polymer gel are disadavantages of this method.
EP Nos. 0287970 and 0251314 describe UV- or electron irradiation~ respectively, to achieve low contents of residual monomers in water-absorbing polymers.
DE-OS 3738602 describes swellable, water-absorbing graft polymers obtained by radical polymerization of -preferably - acrylic acid. However, according to this patent, neither formamidine sulfinic acid is used to manufacture improved water-absorbing polymers nor is there any indication with respect to retention, ab-~. . -- .-.
. .
- ~
' ~
', " ' -h ''!i sorption under load, or residual monomer content of the described graft polymers.
DP 975794 describes the production of cation ex-changers from insoluble polymers of the (meth)acrylic acid or the salts thereof; the trimeric addition prod-uct of formaldehyde to acrylonitrile is used as cross-linking agent. The trimeric addition Product is NlN', N"-trisacryloyl-hexahydrotriazine. According to this patent, the polymerization can be carried out with redox systems consisting of persulfates and sulfoxy-reducing agents; formamidine sulfinic acid is men-tioned amongst others. Highly cross-linked polymers with low retention values are obtained. There are no indications with respect to conversion or residual monomer contents.
The known water-absorbent polymers do not provide the required property combination of high retention and high absorption under load, low content of residual monomers and small amounts of extractable portions.
It is accordingly the object of the present invention to provide a water-absorbing polymer exhibiting high retention and high absorption of aqueous liquids under load, as well as a low content of residual monomers and small amounts of extractable portions.
According to the present invention this object is achieved by a cross-linked, powdery polymer absorbing aqueous liquids or water, this polymer is obtained by polymerization of a mixture of a) 60.0 to 99.9~-wt. unsaturated, polymerizable mono-mers with acid groups which are neutralized to the ex-tent of at least 30 mol-~, .. ~
- ~ ,~ . . . .
- - - .
- . : . . . : . .
-,, . . .- .. . . - , . ~
~ ~ ~ s~
b) 0 to 37%-~t. water-soluble monomers copolymerizable with a), c) 0.1 to 3.0%-wt. of a cross-linking agent, and d) 0 to 10%-wt. of a water-soluble polymer with water as aqueous solution, size reduction, drying, and grinding of the formed polymer, character-ized in that a multiply unsaturated monomer with at least one allylic unsaturated group or mixtures of polyvinyl and polyallyl compounds at a weight ratio of 1 : > 0.6 are used as cross-linking agent according to c), and that the polymerization is carried out using a redox system consisting of formamidine sulfinic acid and one or several organic peroxides.
These polymers exhibit a retention of greater than or equal to 28 9 0.9~ aqueous NaCl-solution per 1 9 of polymer, an absorption of greater than or equal to 26 9 0.9% NaCl-solution per 1 9 of polymer at a load of 20 g/cm2, and a residual monomer content of less than 700 ppm, preferably less than 500 ppm, and a content of extractable portions of less than 6%.
It is known to use formamidine sulfinic acid combined with peroxides to initiate the polymerization (cf.
Houben-Weyl, "Methoden der organischen Chemie", volume 14/1, page 265); however, surprisingly, it was found that the polymerization in the presence of the redox-catalyst-system formamidine sulfinic acid/peroxide re-sults in a very high conversion rate of the monomers into polymers und that the residual monomer content in the polymer amounts to-<700 ppm. In addition, it could not be foreseen that the retention of the water-. ~
- . . ~ ~ , :
: ~ ' : - , ~ ,,- . , ~ . . . . . .
6 ~ s ., absorbent Dolymers is not deteriorated but - on the contrary - influenced positively, and that the poly-mers also exhibit a high absorption under load.
The water-absorbing polymer is composed by 60 to 99.9%-wt. of unsaturated, polymerizable monomers with acid groups, e.g., acrylic acid, methacrylic acid, 2-acrylamido 2-methylpropane sulfonic acid and mixtures of these monomers; the acid groups are neutralized to the extent of at least 30 mol-~, e.g., as salt of so-dium, potassium or ammonium.
The water-absorbing polymers may comprise as further monomers 0 to 37%-wt. of acrylamide, methacrylamide, hydroxyethyl acrylate, dimethylaminopropyl acrylate, dimethylaminopropyl acrylamide, or acrylamidopropyl trimethylammonium chloride. More than 37% of these monomers will deteriorate the swellability of the polymers.
.
The multiply unsaturated monomers with at least one allylic unsaturated group according to claim 1 are selected from the compound classes:
a) allyl esters, e.g., triallyl citrate, diallyl male-inate, allyl(meth)acrylate, b) polyallyl ethers, e.g., glycerol triallyl ether, polyalkylene glycol ether of the allyl glycidic ether, c) allyl amides, e.g., N,N'-diallyl succinic acid di-amide, N,N,N',N'-tetraallyl oxalic acid diamide, N-allyl acrylamide, N-diallyl(meth)acrylamide, or ~ ., . . . - . - . .
~, d) polyallyl amines~ e.g.. triallyl amine, tetraallyl ammonium chloride, methyl ~riallyl ammonium chloride, N,N'-tetraallyl ethylenediamine, N,N'-tetraallyl bu-tanediamine.
0 to 10%-wt. of partially or completely saponified polyvinyl alcohol, polyvinylpryrrolidone, starch or starch derivatives may be contained in the water-ab-sorbing polymer as water-soluble polymers. The molec-ular weight of these polymers is not critical as long as they are water-soluble.
The polymerization is carried out as solvent polymeri-zation either in batches or continuously. For this purpose, the monomers and the cross-linking agent are dissolved in water so that the monomer concentration of the polymerizing mixture amounts to 20 to 35%; the desired neutralization degree is adjusted by addition of a base, the neutralization degree shall amount to at least 30 mol-%. Wetting agents may optionally be added to the monomer solution.
The polymerization may also be carried out in the dis-perse state as inverse suspension or emulsion polymer-ization.
According to the present invention, the polymerization is carried out with a redox-catalyst-system comprising formamidine sulfinic acid as the reducing component and organic peroxides as oxidizing component. Cumene hydroperoxide and tertiary butyl hydroperoxide are preferred because of their water-solubility.
The formamidine sulfinic acid may also be formed in situ' from thiourea and hydrogen peroxide. 'In situ , . .
., ~
is to be understood in such a way that thiourea and hydrogen peroxide instead of formamidine sulfinic acid are added to the monomer solution and that the thio-urea is oxidized in the monomer solution to form form-amidine sulfinic acid.
The amount of the redox catalyst is in the usual range and amounts to about 100 to 2000 ppm formamidine sul-finic acid, relative to monomer solution, and to 100 to 4000 ppm peroxide.
In addition to formamidine sulfinic acid a second reducing agent may be used in an amount of up to 10%-wt., relative to formamidine sulfinic acid, examples thereof include ascorbic acid, sulfite, dihydroxy-maleic acid, or hydroxylamine.
Azo compounds, such as azo bisamidinopropane-hydro-chloride, may be used as further components of the polymerization catalysis.
The polymerization may be initiated by the formamidine sulfinic acid or by its alkali salts, or by means of a co-reducing agent or UV-light.
After polymerization, the polymer gel is reduced in size, dried, and screened to the desired particle size.
For the purpose of characterizing the water-absorbing polymers, the Polymer powder is screened out to lO0-850 ~m, and this fraction is then optionally mixed with 0.1 to 1.0~ of a fumed silica, preferably with 0.5~ Aerosil 200; subsequently, retention, absorption ~ . .
- , .: : :
, . ~, , :~ : ~. :, .
:- : :' - ~ ' -:
under load, and content or residual monomers and ex-tractable proportions are measured.
The retention is determined according to the tea bag test method and reported as avera3e value of three measurements: approximately 200 mg polymer are en-closed in a tea bag and immersed in 0.9% aqueous NaCl-solution for 10 minutes. Then the tea bag is centri-fuged at 1400 rpm in a centrifuge for 5 minutes and weighed. One tea bag without water-absorbing polymer is used as blank.
Weignt - blank reading Retention = (9/9 Initial weight The absorption under load was determined with a Demand-Absorbency testing device (cf. `'Allgemeiner Flie~stoff-Report" 5~82, page 210-218), the test desk was substituted for a Buchner funnel. The Buchner fun-nel is 6.0 cm in diameter and adjusted such that the fluid level is on the level of the ceramic filter plate. A surface-ground cylinder having a diameter of 5.9 cm is used as punch the weight of ~hich exerts a pressure of 20 g/cm2.
For measuring purposes round filter paper is placed in the Buchner-funnel and 0.85 9 of water-absorbing poly-mer of the size fraction 300 to 600 ~m is evenly sprinkled thereon. Subsequently, the cylinder is in-serted and the liquid stopping device opened. 0.9%
aqueous NaCl-solution is used as test liquid. After one hour, the liquid absorption is read from the burette as consumption.
The residual monomer content in the water-absorbing polymers is determined by HPLC. To determine the sol-uble portion, the water-absorbing resin is stirred in 0.9% NaCl-solution for one hour, then it was filtered and the content of acid groups measured in the fil-trate.
Example 1:
-An aqueous acrylic acid solution comprising 0.5% di-allyl acrylamide, relative to acrylic acid, was neu-tralized with sodium hydroxide solution under cooling.
The acrylic acid concentration of the monomer solution amounted to 30%, the neutralization degree to 70%. 850 g of the monomer solution was cooled to 10C and purged with nitrogen for 10 minutes. Subsequently, 3 9 tertiary butyl hydroperoxide, 4.5 mg ascorbic acid, dissolved in 10 9 water, and 500 mg formamidine sul-finic acid, dissolved in 20 9 water, was added. Poly-merization started immediately, this could be recog-nized by a temperature elevation of the monomer solu-tion. After 30 minutes, the obtained polymer gel block was crumbled and dried in hot air at 150C.
Subsequently, the polymer was ground, screened out to 100 to 850 ~m and mixed with 0.5% Aerosil 200. Ihe wa-ter-absorbing polymer exhibited the following proper-ties:
Retention: 29 9/9 Absorption under load: 27 9/9 Content of resid. monomers: 255 ppm Extractable por-tion: 4.9%
. . :
- ;~
, :
1 1 ~. q~l $ ~
Ex mple 2.
2.5 9 tertiary butyl hydroperoxide and 500 mg form-amidine sulfinic acid. dissolved in 30 9 buf~er solu-tion of pH 8, were mixed to 850 9 monomer solution according to Example 1, except that 0.55 % diallyl acrylamide had been used. Polymerization started im-mediately. After 30 minutes, the resulting block of polymer gel was crumbled and dried at 150C in hot air.
The polymer was ground, sieved out to 100 to 850 ~m and mixed with 3.5% Aerosil 200. The water-absorbent polymer had the following properties:
Retention: 29 9~9 Absorption under load:26 9/9 Residual monomer content: 390 ppm Extractable portion: 4.4%
Example 3.
850 9 monomer solution according to Example 2 was mixed with 2.5 9 tertiary butyl hydroperoxide and 400 mg formamidine sulfinic acid which was neutralized with sodium hydroxide solution by 10 mol-æ and dis-solved in 30 9 water. The polymerization started im-mediately. The resulting polymer gel block was worked up into a water-absorbing polymer as described in Ex-ample 2.
Retention: 31.5 9/9 Absorption under load:27.0 9/9 Residual monomer content: 370 ppm Extractable portion: 5.0%
.: . ~ . , : - , . . . ...
12 ~ J r~ O
Examr~le 4:
An aqueous solution of acrylic acid comprising 0.9~
triallyl amine, relative to acrylic acid, was neutral-ized to the extent of 70 mol-% with potassium hydrox-ide solution under cooling; the acrylic acid concen-tration amounted to 28%.
, 850 9 of the monomer solution was cooled to 10C and purged with nitrogen for 10 minutes. Subsequently, 3 g tertiary butyl hydroperoxide, 500 mg formamidine sul-finic acid, dissolved in 20 9 water, and 4.5 mg ascor-bic acid, dissolved in 10 9 water, was added. Polym-erization started immediately. After 30 minutes, the obtained polymer gel block was worked up into a water-absorbing polymer as outlined in Example 1.
~ .
Retention: 29.5 9/9 Absorption under load: 27.0 9/9 Residual monomer content: 290 Extractable portion:4.5 ComDarative ExamPles 5 to 8:
The`properties of four water-absorbing polymers, dis-tributed by Norsolor, Dow Chemical, Allied Colloids, and Chemische Fabrik Stockhausen, are listed in Table I. They are cross-linked, partially neutralized poly-acrylates.
, .. . .
:: : - ~ . :
- . - - , . ~:
:
Table I
Retention Absorption Rasidual under load monomer content 9/9 9/9 ppm Norsocryl B 32 18 130 Drytech 510 33 12 560 Salsorb 90 P 28 21 500 Favor SAB 922 39 9 350 ExamPles 9 to 12: --Aqueous acrylic acid solutions were neutralized with varying amounts of sodium hydroxide solution and poly-merized in accordance with Example 1. Table II shows the polymerization conditions and the properties of the water-absorbing polymers.
., .. ~ , .
.
2~$~.?~' Table II
Example acrylic acid neutraliza- ascorbic concentration tion degree TAA acid t.-BHP
_________________________________________________________________ 9 25æ 70% 0.8% 2 mg 3.0 9 10 30% 50% 0.9~ 4 mg 2.5 g 11 28% 9o% 0.8% 9 mg 2.0 9 12 30% 70% 1,0% 4 mg 2.5 9 Tab 1 e I I ( cont i nued ):
Example FAS Reten- Absorpt. Residual Extr tion under monomer por-load content tion _________________._______________________________________________ 9 250 mg 32 9/9 29 9/9 380 ppm 5.5 500 mg 31 g/g 27 9/9 220 ppm 4.7%
11 500 mg 28 g/g 26 9/9 430 ppm 4.7%
12 500 mg 30 9/9 29 9/9 330 ppm 3.9%
~ ): 2.5 9 of cumene hydroperoxide instead of tertiary butyl hydroperoxide were used in Example 12.
TAA = trial 1y1 amine t.-BHP = tertiary butyl hydroxyperoxide FAS = formamidine sulfinic acid , ~' :
Q ?~
ExamPles 13 to 17:
Acrylic acid (AcA) was copolymerized in aqueous solu-tion in the presence of 1% triallyl amine with meth-acrylic acid (MAA), acrylamide (AA~, 2-acrylamido-2-methylpropane sulfonic acid (AMPS) or dimethylamino-propyl acrylamide (DIMAPA). The monomer concentration amounted to 30%, the neutralization degree to 70~. 9 mg ascorbic acid, 3 g tertiary butyl hydroperoxide, and 500 mg formamidine sulfinic acid were used as cat-alyst system; Table III shows the copolymer composi-tion and the properties of the water-absorbing poly-mers:
Table III
Example AcA Comonomer Retention ~-wt. %-wt.
_____________________________________________ 13 90 10 AMPS 31.5 9/9 14 65 35 AMPS 30~5 g~g 25 AA 30.0 9/9 16 70 30 MAA 29.0 9/9 17 90 10 DIMAPA 31.Q 9/9 - ~ .
, , ' . - : - ~
.
1 6 ~ J ~ ~ i l abl e I I I ( contl nued ):
Example Absorption Residual Extractable under load monomer portion content ___________________________________________________ 13 29.5 9/9 380 ppm 3,5%
14 28.5 9/9 290 ppm 2.0%
28.0 9/9 370 ppm 2.2~
16 28.0 9/9 220 ppm 4.8%
17 28.0 9/9 240 ppm 5.2%
Comparative Examples 18 to 23:
850 monomer solution with 30% acrylic acid neutralized to the extent of 70 mol-% was initiated with various catalysts; the catalysts and the properties of the ob-tained water-absorbing polymers are listed in Table IV.
Table IV
Example TAA ascorbic t-BHP SPS H202 ABAH
% acid ____________________________ __________ ______________ 18 1.0 9 mg 3 9 19 1.0 9 mg 3 g 1 9 1.0 9 mg 3 9 0.69 21 1~0 9 mg 0.69 50 mg 22 0.9 2 9 23 0.8 2 9 SPS = sodium peroxidisulfate Table IV (continued):
xample dithionite formaldehyde- Retention sulfoxylate ________________ ________ __________________________ 18 27 g/g 25 9~9 22 0.5 9 30 9/9 23 100 mg 31 9/9 able IV (continued):
Example Absorption Residual Extractable under load monomer portion content ______________________________________________________ 18 22 9/9 3.380 ppm 4.1%
19 29 9~9 2.430 ppm 5.1%
27 9/9 1.960 ppm 5.6%
21 27 9/9 1.490 ppm 5.6%
22 26 9~9 6.200 ppm 6.2%
23 22 9~9 9.110 ppm 4.9%
xamPles 24 to 32:
Various cross-linking agents were added to 850 9 mono-mer solution with 30% acrylic acid which had been neutralized to 70 mol-% by sodium hydroxide solu-tion. As described in Example 1, the polymerization was then initiated with 4.5 mg ascorbic acid, dis-solved in 10 9 water, 3 9 tertiary butyl hydroperox-.
, 18 C~ 33~-ide, and 500 mg formamidine sulfinic acid, dissolved in 20 9 water. The properties of the obtained water-absorbing polymers are listed in Table V:
Table V
Example Cross-linking agentRetention 24 0.8% TMPTA 80 9/9 Comparison 1.2% TMPTA 29 9/9 Comparison 26 0.5% TMPTA / 0.4% TAA28 9/9 27 0.5~ TMPTA / 0.8~ TAC29 9/9 28 11.1% N-trisacryloyl-hexa- 9 g/g Comparison1 hydrotriazine 29 0.3% N-trisacryloyl-hexa- 24 g/g Comparison2 hydrotriazine 0.25% MBA / 0.25% TAA28 9/9 31 1.0% N,N'-tetraallyl butane- 31 g/g diamine 32 0.5% N-allyl acrylamide 28 9/9 .- . .: .
19 ~;3$~
able V (continued):
Example AbsorptionResidual Extractable under load monomer portion content ______________________________________________________ 24 17 g/g 210 ppm 12.3%
Comparison 18 9/9 340 ppm 11.0%
Comparison 26 9~9 405 ppm 5.8%
27 27 9/9 470 ppm 5.6%
28 10 9/9 8.1% 0~8%
Comparison1 29 24 9~9 6.9% 2~2%
Comparison2 26 9/9 290 ppm 5.8%
31 28.5 9/9390 ppm 4.3%
32 28 9/9 230 ppm 3.8%
TMPTA = trimethylolpropane triacrylate TAA = triallyl amine TAC = triallyl citrate M8A = ~ethylene bisacrylamide ~ 3`~
': Example 28 was produced according to example 1 of 2: Example 29 was produced using 0.35 g formamidine sulfinic acid/0.5 9 persulfate~9 mg ascorbic acid.
Example 33 850 ml monomer solution according to Example 1 with 1%
triallyl amine instead of diallyl acrylamide and addi-tionally comprising 6.7 9 dissolved polyvinyl alcohol was polymerized as in Example 1 and processed to form a water-absorbing polymer comprising 2% polyvinyl alcohol.
Retention: 30 9/9 Absorption under load: 29 9/9 Residual monomer content: 370 ppm Extractable portion:3 9 %
Example 34:
An aqueous acrylic acid solution comprising 0.7% tri-allyl amine was neutralized with sodium hydroxide so-lution under cooling; an aqueous starch solution (type: Sorbex 222 of Sudstarke GmbH, FRG) was added then. The acrylic acid concentration amounted to 26.5~ ;
and the neutralization degree to 70 mol-%. 935 9 of this monomer solution was cooled to 10C, purged with nitrogen for 10 minutes, and mixed with 3 9 tertiary butyl hydroperoxide, 500 mg formamidine sulfinic acid, dissolved in 20 9 water, and 4.5 mg ascorbic acid, dissolved in 10 9 water. The polymerization started immediately. After 30 minutes the obtained gel block , . , - : : , ~: : -was crumbled and dried at 110C with hot air. The dry polymer comprises 8.5% starch.
Retention: 30.5 9/9 Absorption under load: 27.~ g/g Residual monomer content: 310 ppm Extractable portion: 5.2%
ExamDle 35:
850 9 monomer solution of Example 1 but with 1% tri-allyl amine instead of diallyl acrylamids was cooled to 10C and purged with nitrogen for 10 minutes. Sub-sequently, 0.35 9 thiourea, dissolved in 20 9 water, 1.0 9 hydrogen peroxide, 3 9 tertiary butyl hydroper-oxide, and 5 mg ascorbic acid, dissolved in 10 9 wa-ter, was added to the monomer solution according to the given order, whereupon the polymerization started immediately. After 30 minutes, the resultant polymer gel block was crushed and dried at 150C with hot air.
Retention: 28 9/9 Absorption under load: 28 9/9 Residual monomer content: 400 ppm Extractable portion: 4.3 %
The use of the water-absorbing polymers according to the present invention was tested in sandwiched con-structions consisting of fluff and water-absorbing polymer. Round constructions consisting of 3 fluff layers and 2 layers of water-absorbing polymer (diam-eter: 5.8 cm) were placed in the Buchner funnel deter-mining the absorption under load. At a pressure load of 20 g/cm2 the constructions are allowed to suck 0.9%
~ . :' ': ' ' :
: ~: : . .
NaCl-solution for 150 minutes, then the absorption of the water-absorbent polymer is calculated as follows:
(consumption blank in burette) - for fluff) Absorption Initial weight Table VI
ADDlication ExamDles 36 to 41:
______________________________________________________ Example Polymer of Portion Absorption Example Polymer (1) in construction (ml/g) ______________________________________________________ Comparative Example FAVOR SAB 922 (2) 20 29 FAVOR SAB 954 (2) 20 23 _____________________________________________ _______ (1) ~-wt., relative to fluff (2) Commercial products of Chemische Fabrik Stockhausen GmbH~
,.
: ~
., . ~ - . ,~ - . ..
. . .. . . . -- - : . , .... ;~
. . : .
- ~
- : . - . . ~ . .
The polymer was ground, sieved out to 100 to 850 ~m and mixed with 3.5% Aerosil 200. The water-absorbent polymer had the following properties:
Retention: 29 9~9 Absorption under load:26 9/9 Residual monomer content: 390 ppm Extractable portion: 4.4%
Example 3.
850 9 monomer solution according to Example 2 was mixed with 2.5 9 tertiary butyl hydroperoxide and 400 mg formamidine sulfinic acid which was neutralized with sodium hydroxide solution by 10 mol-æ and dis-solved in 30 9 water. The polymerization started im-mediately. The resulting polymer gel block was worked up into a water-absorbing polymer as described in Ex-ample 2.
Retention: 31.5 9/9 Absorption under load:27.0 9/9 Residual monomer content: 370 ppm Extractable portion: 5.0%
.: . ~ . , : - , . . . ...
12 ~ J r~ O
Examr~le 4:
An aqueous solution of acrylic acid comprising 0.9~
triallyl amine, relative to acrylic acid, was neutral-ized to the extent of 70 mol-% with potassium hydrox-ide solution under cooling; the acrylic acid concen-tration amounted to 28%.
, 850 9 of the monomer solution was cooled to 10C and purged with nitrogen for 10 minutes. Subsequently, 3 g tertiary butyl hydroperoxide, 500 mg formamidine sul-finic acid, dissolved in 20 9 water, and 4.5 mg ascor-bic acid, dissolved in 10 9 water, was added. Polym-erization started immediately. After 30 minutes, the obtained polymer gel block was worked up into a water-absorbing polymer as outlined in Example 1.
~ .
Retention: 29.5 9/9 Absorption under load: 27.0 9/9 Residual monomer content: 290 Extractable portion:4.5 ComDarative ExamPles 5 to 8:
The`properties of four water-absorbing polymers, dis-tributed by Norsolor, Dow Chemical, Allied Colloids, and Chemische Fabrik Stockhausen, are listed in Table I. They are cross-linked, partially neutralized poly-acrylates.
, .. . .
:: : - ~ . :
- . - - , . ~:
:
Table I
Retention Absorption Rasidual under load monomer content 9/9 9/9 ppm Norsocryl B 32 18 130 Drytech 510 33 12 560 Salsorb 90 P 28 21 500 Favor SAB 922 39 9 350 ExamPles 9 to 12: --Aqueous acrylic acid solutions were neutralized with varying amounts of sodium hydroxide solution and poly-merized in accordance with Example 1. Table II shows the polymerization conditions and the properties of the water-absorbing polymers.
., .. ~ , .
.
2~$~.?~' Table II
Example acrylic acid neutraliza- ascorbic concentration tion degree TAA acid t.-BHP
_________________________________________________________________ 9 25æ 70% 0.8% 2 mg 3.0 9 10 30% 50% 0.9~ 4 mg 2.5 g 11 28% 9o% 0.8% 9 mg 2.0 9 12 30% 70% 1,0% 4 mg 2.5 9 Tab 1 e I I ( cont i nued ):
Example FAS Reten- Absorpt. Residual Extr tion under monomer por-load content tion _________________._______________________________________________ 9 250 mg 32 9/9 29 9/9 380 ppm 5.5 500 mg 31 g/g 27 9/9 220 ppm 4.7%
11 500 mg 28 g/g 26 9/9 430 ppm 4.7%
12 500 mg 30 9/9 29 9/9 330 ppm 3.9%
~ ): 2.5 9 of cumene hydroperoxide instead of tertiary butyl hydroperoxide were used in Example 12.
TAA = trial 1y1 amine t.-BHP = tertiary butyl hydroxyperoxide FAS = formamidine sulfinic acid , ~' :
Q ?~
ExamPles 13 to 17:
Acrylic acid (AcA) was copolymerized in aqueous solu-tion in the presence of 1% triallyl amine with meth-acrylic acid (MAA), acrylamide (AA~, 2-acrylamido-2-methylpropane sulfonic acid (AMPS) or dimethylamino-propyl acrylamide (DIMAPA). The monomer concentration amounted to 30%, the neutralization degree to 70~. 9 mg ascorbic acid, 3 g tertiary butyl hydroperoxide, and 500 mg formamidine sulfinic acid were used as cat-alyst system; Table III shows the copolymer composi-tion and the properties of the water-absorbing poly-mers:
Table III
Example AcA Comonomer Retention ~-wt. %-wt.
_____________________________________________ 13 90 10 AMPS 31.5 9/9 14 65 35 AMPS 30~5 g~g 25 AA 30.0 9/9 16 70 30 MAA 29.0 9/9 17 90 10 DIMAPA 31.Q 9/9 - ~ .
, , ' . - : - ~
.
1 6 ~ J ~ ~ i l abl e I I I ( contl nued ):
Example Absorption Residual Extractable under load monomer portion content ___________________________________________________ 13 29.5 9/9 380 ppm 3,5%
14 28.5 9/9 290 ppm 2.0%
28.0 9/9 370 ppm 2.2~
16 28.0 9/9 220 ppm 4.8%
17 28.0 9/9 240 ppm 5.2%
Comparative Examples 18 to 23:
850 monomer solution with 30% acrylic acid neutralized to the extent of 70 mol-% was initiated with various catalysts; the catalysts and the properties of the ob-tained water-absorbing polymers are listed in Table IV.
Table IV
Example TAA ascorbic t-BHP SPS H202 ABAH
% acid ____________________________ __________ ______________ 18 1.0 9 mg 3 9 19 1.0 9 mg 3 g 1 9 1.0 9 mg 3 9 0.69 21 1~0 9 mg 0.69 50 mg 22 0.9 2 9 23 0.8 2 9 SPS = sodium peroxidisulfate Table IV (continued):
xample dithionite formaldehyde- Retention sulfoxylate ________________ ________ __________________________ 18 27 g/g 25 9~9 22 0.5 9 30 9/9 23 100 mg 31 9/9 able IV (continued):
Example Absorption Residual Extractable under load monomer portion content ______________________________________________________ 18 22 9/9 3.380 ppm 4.1%
19 29 9~9 2.430 ppm 5.1%
27 9/9 1.960 ppm 5.6%
21 27 9/9 1.490 ppm 5.6%
22 26 9~9 6.200 ppm 6.2%
23 22 9~9 9.110 ppm 4.9%
xamPles 24 to 32:
Various cross-linking agents were added to 850 9 mono-mer solution with 30% acrylic acid which had been neutralized to 70 mol-% by sodium hydroxide solu-tion. As described in Example 1, the polymerization was then initiated with 4.5 mg ascorbic acid, dis-solved in 10 9 water, 3 9 tertiary butyl hydroperox-.
, 18 C~ 33~-ide, and 500 mg formamidine sulfinic acid, dissolved in 20 9 water. The properties of the obtained water-absorbing polymers are listed in Table V:
Table V
Example Cross-linking agentRetention 24 0.8% TMPTA 80 9/9 Comparison 1.2% TMPTA 29 9/9 Comparison 26 0.5% TMPTA / 0.4% TAA28 9/9 27 0.5~ TMPTA / 0.8~ TAC29 9/9 28 11.1% N-trisacryloyl-hexa- 9 g/g Comparison1 hydrotriazine 29 0.3% N-trisacryloyl-hexa- 24 g/g Comparison2 hydrotriazine 0.25% MBA / 0.25% TAA28 9/9 31 1.0% N,N'-tetraallyl butane- 31 g/g diamine 32 0.5% N-allyl acrylamide 28 9/9 .- . .: .
19 ~;3$~
able V (continued):
Example AbsorptionResidual Extractable under load monomer portion content ______________________________________________________ 24 17 g/g 210 ppm 12.3%
Comparison 18 9/9 340 ppm 11.0%
Comparison 26 9~9 405 ppm 5.8%
27 27 9/9 470 ppm 5.6%
28 10 9/9 8.1% 0~8%
Comparison1 29 24 9~9 6.9% 2~2%
Comparison2 26 9/9 290 ppm 5.8%
31 28.5 9/9390 ppm 4.3%
32 28 9/9 230 ppm 3.8%
TMPTA = trimethylolpropane triacrylate TAA = triallyl amine TAC = triallyl citrate M8A = ~ethylene bisacrylamide ~ 3`~
': Example 28 was produced according to example 1 of 2: Example 29 was produced using 0.35 g formamidine sulfinic acid/0.5 9 persulfate~9 mg ascorbic acid.
Example 33 850 ml monomer solution according to Example 1 with 1%
triallyl amine instead of diallyl acrylamide and addi-tionally comprising 6.7 9 dissolved polyvinyl alcohol was polymerized as in Example 1 and processed to form a water-absorbing polymer comprising 2% polyvinyl alcohol.
Retention: 30 9/9 Absorption under load: 29 9/9 Residual monomer content: 370 ppm Extractable portion:3 9 %
Example 34:
An aqueous acrylic acid solution comprising 0.7% tri-allyl amine was neutralized with sodium hydroxide so-lution under cooling; an aqueous starch solution (type: Sorbex 222 of Sudstarke GmbH, FRG) was added then. The acrylic acid concentration amounted to 26.5~ ;
and the neutralization degree to 70 mol-%. 935 9 of this monomer solution was cooled to 10C, purged with nitrogen for 10 minutes, and mixed with 3 9 tertiary butyl hydroperoxide, 500 mg formamidine sulfinic acid, dissolved in 20 9 water, and 4.5 mg ascorbic acid, dissolved in 10 9 water. The polymerization started immediately. After 30 minutes the obtained gel block , . , - : : , ~: : -was crumbled and dried at 110C with hot air. The dry polymer comprises 8.5% starch.
Retention: 30.5 9/9 Absorption under load: 27.~ g/g Residual monomer content: 310 ppm Extractable portion: 5.2%
ExamDle 35:
850 9 monomer solution of Example 1 but with 1% tri-allyl amine instead of diallyl acrylamids was cooled to 10C and purged with nitrogen for 10 minutes. Sub-sequently, 0.35 9 thiourea, dissolved in 20 9 water, 1.0 9 hydrogen peroxide, 3 9 tertiary butyl hydroper-oxide, and 5 mg ascorbic acid, dissolved in 10 9 wa-ter, was added to the monomer solution according to the given order, whereupon the polymerization started immediately. After 30 minutes, the resultant polymer gel block was crushed and dried at 150C with hot air.
Retention: 28 9/9 Absorption under load: 28 9/9 Residual monomer content: 400 ppm Extractable portion: 4.3 %
The use of the water-absorbing polymers according to the present invention was tested in sandwiched con-structions consisting of fluff and water-absorbing polymer. Round constructions consisting of 3 fluff layers and 2 layers of water-absorbing polymer (diam-eter: 5.8 cm) were placed in the Buchner funnel deter-mining the absorption under load. At a pressure load of 20 g/cm2 the constructions are allowed to suck 0.9%
~ . :' ': ' ' :
: ~: : . .
NaCl-solution for 150 minutes, then the absorption of the water-absorbent polymer is calculated as follows:
(consumption blank in burette) - for fluff) Absorption Initial weight Table VI
ADDlication ExamDles 36 to 41:
______________________________________________________ Example Polymer of Portion Absorption Example Polymer (1) in construction (ml/g) ______________________________________________________ Comparative Example FAVOR SAB 922 (2) 20 29 FAVOR SAB 954 (2) 20 23 _____________________________________________ _______ (1) ~-wt., relative to fluff (2) Commercial products of Chemische Fabrik Stockhausen GmbH~
,.
: ~
., . ~ - . ,~ - . ..
. . .. . . . -- - : . , .... ;~
. . : .
- ~
- : . - . . ~ . .
Claims (8)
1. A cross-linked, powdery Polymer absorbing aqueous liquids or water, obtainable by Polymerizing a mixture consisting of a) 60.0 to 99.9x-wt. uneaturated, polymerizable mono-mers with acid groups which are neutralized to the ex-tent of at least 30 mol-%, b) 0 to 37%-wt. water-soluble monomers copolymerizable with a), c) 0.1 to 3.0%-wt. of a cross-linking agent, and d) o to 10%-wt. of water-soluble polymers, with water as aqueous solution, crumbling, drying, and grinding the formed polymer, characterized in that a multiply unsaturated monomer with at least one allylically unsaturated group or mixtures of polyvinyl and polyallyl compositions at a weight ratio of 1 : > 0.6 is used as cross-linking agent according to c), and that the polymerization is carried out with a redox system consisting of form-amidine sulfinic acid and one or more organic per-oxides.
2. The cross-linked polymer absorbing aqueous liquids or water according to claim 1, characterized by a re-tention of greater than or equal to 28 g 0.9% aqueous NaC1-solution per 1 g of polymer, an absorption of greater than or equal to 28 g 0.9% aqueous NaCl-solu-tion per 1g of polymer under a load of 20 g/cm2, a residual monomer content of less than 700 ppm, prefer-ably less than 500 ppm, and a content of extractable portions of less than 6%-wt.
3. The cross-linked polymer absorbing aqueous liquids or water according to claims 1 and 2, wherein the re-dox catalyst system may comprise further reducing agents in addition to formamindine sulfinic acid.
4. The cross-linked polymer absorbing aqueous liquids or water according to any one of claims 1 to 3, where-in the formamidine sulfinic acid is formed "in situ"
from thiourea and hydrogen peroxide.
from thiourea and hydrogen peroxide.
5. The cross-linked polymer absorbing aqueous liquids or water according to any one of claims 1 to 4, where-in acrylic acid, methacrylic acid and 2-acrylamido-2-methylpropane sulfonic acid or mixtures of said mono-mers are used as acid-groups-containing monomers.
6. The cross-linked polymer absorbing aqueous liquids or water according to any one of claims 1 to 4, where-in polyvinyl alcohol, polyvinylpyrrolidone, starch or starch derivatives are used as water-soluble polymers.
7. The use of the cross-linked, aqueous liquids or wa-ter absorbing polymer as defined in claims 1 to 6 in the production of hygiene articles.
8. The use of the cross-linked, aqueous liquids or wa-ter absorbing polymer according to claim 6 in the pro-duction of constructions which are capable of absorb-ing body liquids and are suitable for the use in dia-pers and hygiene articles, consisting of 98 to 30%-wt.
of hydrophilic fibers and 2 to 70% of a water-absorb-ing polymer.
of hydrophilic fibers and 2 to 70% of a water-absorb-ing polymer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4015085A DE4015085C2 (en) | 1990-05-11 | 1990-05-11 | Crosslinked, water-absorbent polymer and use for the manufacture of hygiene articles, for soil improvement and in cable sheathing |
| DEP4015085.2 | 1990-05-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2082506A1 true CA2082506A1 (en) | 1991-11-12 |
Family
ID=6406153
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002082506A Abandoned CA2082506A1 (en) | 1990-05-11 | 1991-05-10 | Cross-linked, water-absorbent polymer and its use in the production of hygiene items |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0527867B1 (en) |
| JP (1) | JP3076853B2 (en) |
| AT (1) | ATE111924T1 (en) |
| AU (1) | AU648559B2 (en) |
| CA (1) | CA2082506A1 (en) |
| DE (2) | DE4015085C2 (en) |
| ES (1) | ES2037637T3 (en) |
| GR (1) | GR930300039T1 (en) |
| WO (1) | WO1991018031A1 (en) |
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| DE4206850C2 (en) * | 1992-03-05 | 1996-08-29 | Stockhausen Chem Fab Gmbh | Polymer compositions, preparation of polymer compositions, in particular absorption materials and their use |
| US5416160A (en) * | 1992-06-19 | 1995-05-16 | The Dow Chemical Company | Water-swellable polymers having improved color |
| DE4435422A1 (en) * | 1994-10-04 | 1996-04-18 | Basf Ag | Process for the preparation of an aqueous polymer dispersion |
| DE19529348C2 (en) * | 1995-08-09 | 1997-11-20 | Stockhausen Chem Fab Gmbh | Absorbent for water and aqueous liquids based on polyacrylate and process for their production and use |
| AU731439B2 (en) * | 1996-12-13 | 2001-03-29 | Dsg International Limited | Highly absorbent composite and method of making the same |
| DE19854573A1 (en) | 1998-11-26 | 2000-05-31 | Basf Ag | Process for post-crosslinking hydrogels with 2-oxo-tetrahydro-1,3-oxazines |
| MXPA02010067A (en) * | 2000-04-13 | 2004-08-19 | Sanyo Chemical Ind Ltd | Crosslinked polymer, process for producing the same, absorbent structure, and absorbent article. |
| AU2002212325A1 (en) * | 2000-10-18 | 2002-04-29 | Basf Aktiengesellschaft | Hydrogel-forming polymers |
| DE10225943A1 (en) | 2002-06-11 | 2004-01-08 | Basf Ag | Process for the preparation of esters of polyalcohols |
| TWI378955B (en) * | 2002-10-25 | 2012-12-11 | Evonik Stockhausen Gmbh | Absorbent polymer structure with improved retention capacity and permeabilty |
| EP1736508A1 (en) | 2005-06-22 | 2006-12-27 | Basf Aktiengesellschaft | Hydrogel-forming polymers with increased permeability and high absorption capacity |
| JP2019094444A (en) * | 2017-11-24 | 2019-06-20 | Ｓｄｐグローバル株式会社 | Water-absorbable resin particle and production method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE861155C (en) * | 1941-02-22 | 1952-12-29 | Hoechst Ag | Process for emulsion polymerization in the simultaneous presence of oxidizing agents and reducing agents |
| DE926091C (en) * | 1942-07-21 | 1955-04-07 | Hoechst Ag | Process for the production of polymers or copolymers of simply unsaturated compounds |
| US4115339A (en) * | 1971-11-18 | 1978-09-19 | Hercules Incorporated | High molecular-weight, water-soluble vinyl polymers |
| JPS51125468A (en) * | 1975-03-27 | 1976-11-01 | Sanyo Chem Ind Ltd | Method of preparing resins of high water absorbency |
| US4286082A (en) * | 1979-04-06 | 1981-08-25 | Nippon Shokubai Kagaku Kogyo & Co., Ltd. | Absorbent resin composition and process for producing same |
| CA1178744A (en) * | 1979-07-11 | 1984-11-27 | Daniel F. Herman | Polymeric electrolytes |
| DE3124008A1 (en) * | 1981-06-19 | 1983-01-27 | Chemische Fabrik Stockhausen & Cie, 4150 Krefeld | CROSSLINKED, WATER-SWELLABLE COPOLYMERS AND THEIR USE AS AN ABSORBENT FOR AQUEOUS BODY LIQUIDS LIKE URINE |
| US4677174A (en) * | 1986-04-21 | 1987-06-30 | American Colloid Company | Water absorbent styrene-acrylic acid copolymers |
| DE3312424A1 (en) * | 1983-04-07 | 1984-10-11 | Basf Ag, 6700 Ludwigshafen | Process for the preparation of bead-form polymers |
| US4666975A (en) * | 1984-03-05 | 1987-05-19 | Kao Corporation | Absorptive material |
| FR2575479B1 (en) * | 1984-12-27 | 1987-02-27 | Charbonnages Ste Chimique | AMPHOTERIC COPOLYMERS, THEIR MANUFACTURING PROCESS AND THEIR APPLICATION TO WATER RETENTION |
| 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 |
| US4616063A (en) * | 1985-03-06 | 1986-10-07 | Atlantic Richfield Company | Water absorbent polymer composition |
| JPS61271303A (en) * | 1985-05-24 | 1986-12-01 | Lion Corp | Production of water-absorptive resin |
| US4654039A (en) * | 1985-06-18 | 1987-03-31 | The Proctor & Gamble Company | Hydrogel-forming polymer compositions for use in absorbent structures |
| CA1284543C (en) * | 1985-06-22 | 1991-05-28 | Kazuo Saotome | Aqueous composition, method of producing a water absorbent polymer, water absorbent polymer-coated article and method of producing the same |
| DE3605332A1 (en) * | 1986-02-19 | 1987-08-20 | Bayer Ag | CHLOROPRENE POLYMERISATION |
| CS263644B1 (en) * | 1986-10-16 | 1989-04-14 | Hudecek Slavko | Copolymers of acrylic or methacrylic acid or alkalic metal salts thereof |
| DE3713601A1 (en) * | 1987-04-23 | 1988-11-10 | Stockhausen Chem Fab Gmbh | METHOD FOR PRODUCING A STRONG WATER-ABSORBENT POLYMER |
| KR0130652B1 (en) * | 1987-08-14 | 1998-04-07 | 존 휴즈 | Improved process for preparing water-absorbing resins |
| US4833222A (en) * | 1987-10-22 | 1989-05-23 | The Dow Chemical Company | Crosslinker stabilizer for preparing absorbent polymers |
| DE3741158A1 (en) * | 1987-12-04 | 1989-06-15 | Stockhausen Chem Fab Gmbh | POLYMERISATES WITH HIGH ABSORPTION SPEED FOR WATER AND AQUEOUS LIQUIDS, METHOD FOR THE PRODUCTION THEREOF AND USE AS ABSORBENTS |
| KR970009239B1 (en) * | 1988-06-16 | 1997-06-09 | 미츠비시유카 가부시키가이샤 | Process for producing highly water absorptive polymer |
-
1990
- 1990-05-11 DE DE4015085A patent/DE4015085C2/en not_active Expired - Fee Related
-
1991
- 1991-05-10 EP EP91909230A patent/EP0527867B1/en not_active Expired - Lifetime
- 1991-05-10 ES ES91909230T patent/ES2037637T3/en not_active Expired - Lifetime
- 1991-05-10 JP JP03508473A patent/JP3076853B2/en not_active Expired - Fee Related
- 1991-05-10 WO PCT/EP1991/000878 patent/WO1991018031A1/en active IP Right Grant
- 1991-05-10 AU AU77897/91A patent/AU648559B2/en not_active Ceased
- 1991-05-10 DE DE59103054T patent/DE59103054D1/en not_active Expired - Lifetime
- 1991-05-10 AT AT91909230T patent/ATE111924T1/en not_active IP Right Cessation
- 1991-05-10 CA CA002082506A patent/CA2082506A1/en not_active Abandoned
-
1993
- 1993-06-07 GR GR930300039T patent/GR930300039T1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| GR930300039T1 (en) | 1993-06-07 |
| JPH05507508A (en) | 1993-10-28 |
| JP3076853B2 (en) | 2000-08-14 |
| DE4015085C2 (en) | 1995-06-08 |
| ES2037637T1 (en) | 1993-07-01 |
| EP0527867A1 (en) | 1993-02-24 |
| ES2037637T3 (en) | 1994-12-01 |
| DE4015085A1 (en) | 1991-12-12 |
| AU7789791A (en) | 1991-12-10 |
| AU648559B2 (en) | 1994-04-28 |
| DE59103054D1 (en) | 1994-10-27 |
| WO1991018031A1 (en) | 1991-11-28 |
| EP0527867B1 (en) | 1994-09-21 |
| ATE111924T1 (en) | 1994-10-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |