Superabsorber mixtures

Abstract

Superabsorbent mixtures M comprising at least 70% by weight of superabsorbent A having a liquid absorption of 20 g/g (T20) of less than 300 s and/or a volumetric liquid absorption under pressure 0.3 psi (2.07 kPa) (VAUL) with a τ value of less than 400 s, and at least 5% by weight of superabsorbent B having a centrifuge retention capacity (CRC) of at least 30 g/g.

Claims

1. A superabsorbent mixture M comprising at least 70% by weight of superabsorbent A having a liquid absorption of 20 g/g (T20) of less than 300 s and/or a volumetric liquid absorption under pressure 0.3 psi (2.07 kPa) (VAUL) with a τ value of less than 400 s, and at least 5% by weight of superabsorbent B having a centrifuge retention capacity (CRC) of at least 30 g/g.

2. The superabsorbent mixture M according to claim 1, wherein superabsorbent A has a liquid absorption of 20 g/g (T20) of less than 240 s and/or a volumetric liquid absorption under pressure 0.3 psi (2.07 kPa) (VAUL) with a τ value of less than 350 s.

3. The superabsorbent mixture M according to claim 1, wherein superabsorbent A has a liquid absorption of 20 g/g (T20) of less than 180 s and/or a volumetric liquid absorption under pressure 0.3 psi (2.07 kPa) (VAUL) with a τ value of less than 250 s.

4. The superabsorbent mixture M according to claim 1, wherein superabsorbent A has a liquid absorption of 20 g/g (T20) of less than 120 s and/or a volumetric liquid absorption under pressure 0.3 psi (2.07 kPa) (VAUL) with a τ value of less than 200 s.

5. The superabsorbent mixture M according to claim 1, wherein superabsorbent B has a centrifuge retention capacity (CRC) of at least 35 g/g.

6. The superabsorbent mixture M according to claim 1, wherein superabsorbent B has a centrifuge retention capacity (CRC) of at least 40 g/g.

7. The superabsorbent mixture M according to claim 1, wherein superabsorbent B has a centrifuge retention capacity (CRC) of at least 45 g/g.

8. The superabsorbent mixture M according to claim 1, wherein superabsorbent A has a mean sphericity (mSPHT) of less than 0.72.

9. The superabsorbent mixture M according to claim 1, wherein superabsorbent B has a mean sphericity (mSPHT) of greater than 0.72.

10. The superabsorbent mixture M according to claim 1, wherein superabsorbent A has a bulk density (ASG) of less than 0.70 g/ml.

11. The superabsorbent mixture M according to claim 1, wherein superabsorbent B has a bulk density (ASG) of greater than 0.70 g/ml.

12. The superabsorbent mixture M according to claim 1, wherein superabsorbent A has been surface postcrosslinked.

13. The superabsorbent mixture M according to claim 1, wherein superabsorbent B has not been surface postcrosslinked.

14. The superabsorbent mixture M according to claim 1, wherein superabsorbent A and/or superabsorbent B has an average particle size of 250 to 500 μm.

15. A hygiene article comprising a superabsorbent mixture M according to claim 1.

Description

EXAMPLES

Production Example 1—Superabsorbent B

(1) A base polymer was produced analogously to example 1 of WO 2017/207330 A1. The neutralization level was 72.0 mol %, and the solids content of the monomer solution was 43.0% by weight.

(2) The polyunsaturated crosslinker used was 3-tuply ethoxylated glycerol triacrylate. The crosslinker was prepared according to example 7 of WO 03/104299 A1. The crosslinker was used in an amount of 0.20% by weight, based on acrylic acid prior to neutralization. In addition, the monomer solution comprised 0.75% by weight of polyethylene glycol-4000 (polyethylene glycol having an average molar mass of 4000 g/mol), again based on acrylic acid prior to neutralization.

(3) Polymerization initiators used were 0.16% by weight of sodium peroxodisulfate, 0.0007% by weight of hydrogen peroxide and 0.0028% by weight of ascorbic acid, based in each case on acrylic acid prior to neutralization.

(4) The superabsorbent (base polymer) produced had a centrifuge retention capacity (CRC) of 44.8 g/g, an absorption under a pressure of 0.0 g/cm.sup.2 (AUNL) of 48.2 g/g, an absorption under a pressure of 21.0 g/cm.sup.2 (AUL) of 7.8 g/g, a free swell capacity (FSC) of 56.9 g/g, a moisture content of 3.2% by weight and a bulk density (ASG) of 0.67 g/ml.

(5) The superabsorbent had the following particle size distribution:

(6) TABLE-US-00001 >710 μm 0.2% by weight 600-710 μm 14.3% by weight 500-600 μm 19.0% by weight 400-500 μm 28.8% by weight 300-400 μm 19.0% by weight 200-300 μm 12.3% by weight 150-200 μm 5.2% by weight 106-150 μm 1.2% by weight <106 μm 0.0% by weight

(7) The superabsorbent had a median particle size (d50) of 430 μm and a mean sphericity (mSPHT) of 0.60.

Production Example 2—Superabsorbent B

(8) 1200 g of the base polymer from production example 1 was introduced into a Pflugschar® M5 plowshare mixer with heating jacket (Gebr. Lödige Maschinenbau GmbH, Paderborn, Germany) and coated at 23° C. and a shaft speed of 200 revolutions per minute by means of a two-phase spray nozzle with the following solution, based in each case on the base polymer:

(9) 0.04% by weight of ethylene glycol diglycidyl ether

(10) 1.5% by weight of propylene glycol

(11) 0.05% by weight of aluminum sulfate

(12) 3.0% by weight of water

(13) The shaft speed was set to 60 revolutions per minute and the product was brought to a temperature of 120° C. In order to maintain this temperature, the temperature of the heating fluid was reduced appropriately. After 30 minutes at 120° C., the sample was cooled to ambient temperature.

(14) Subsequently, the polymer particles obtained were remoisturized in a further mixer at 80° C. For this purpose, 7.0% by weight of a 0.05% by weight aqueous aluminum sulfate solution was sprayed onto the polymer by means of a nitrogen-operated two-phase nozzle and while stirring. While stirring, the polymer was cooled down to 25° C. within 20 minutes and sieved off to a particle size of 150 to 710 μm.

(15) The superabsorbent produced had a centrifuge retention capacity (CRC) of 33.4 g/g, an absorption under a pressure of 0.0 g/cm.sup.2 (AUNL) of 48.3 g/g, an absorption under a pressure of 21.0 g/cm.sup.2 (AUL) of 31.7 g/g, an absorption under a pressure of 49.2 g/cm.sup.2 (AUHL) of 23.9 g/g, a free swell capacity (FSC) of 54.4 g/g, a moisture content of 5.0% by weight, a saline flow conductivity (SFC) of 8×10.sup.−7 cm.sup.3 s/g, a vortex of 52 s, a residual monomer content of 310 ppm and a bulk density (ASG) of 0.67 g/ml.

(16) The superabsorbent had the following particle size distribution:

(17) TABLE-US-00002 >710 μm 0.50% by weight 600-710 μm 11.2% by weight 500-600 μm 20.9% by weight 425-500 μm 24.5% by weight 300-425 μm 23.6% by weight 150-300 μm 18.0% by weight 106-150 μm 0.4% by weight <106 μm 0.0% by weight

(18) The superabsorbent had a median particle size (d50) of 464 μm and a mean sphericity (mSPHT) of 0.60.

Production Example 3—Superabsorbent A

(19) A superabsorbent was produced according to example 14 of WO 2014/118024 A1. The superabsorbent produced had a bulk density (ASG) of 0.60 g/ml, a centrifuge retention capacity (CRC) of 26.0 g/g, an absorption under a pressure of 49.2 g/cm.sup.2 (AUHL) of 23.9 g/g and a saline flow conductivity (SFC) of 136×10.sup.−7 cm.sup.3 s/g.

(20) The superabsorbent had the following particle size distribution:

(21) TABLE-US-00003 >710 μm 8.7% by weight 600-710 μm 19.2% by weight 500-600 μm 26.9% by weight 400-500 μm 21.9% by weight 300-400 μm 14.2% by weight 150-300 μm 9.0% by weight 106-150 μm 0.1% by weight <106 μm 0.0% by weight

(22) The superabsorbent had a median particle size (d50) of 510 μm and a mean sphericity (mSPHT) of 0.66.

Production Example 4—Superabsorbent B

(23) A superabsorbent was produced analogously to example 2 of WO 2016/134905 A1. The monomer solution used additionally comprised 1.07% by weight of the disodium salt of 1-hydroxyethylidene-1,1-diphosphonic acid.

(24) The gas inlet temperature of reaction zone (5) was 167° C., the gas outlet temperature of reaction zone (5) was 107° C., the gas inlet temperature of the internal fluidized bed (27) was 100° C., the product temperature in the internal fluidized bed (27) was 78° C., the gas outlet temperature of the condensation column (12) was 57° C., and the gas outlet temperature of the gas drying unit (37) was 47° C.

(25) The superabsorbent produced (base polymer) had a bulk density (ASG) of 0.681 g/ml, a centrifuge retention capacity (CRC) of 56.8 g/g, an absorption under a pressure of 21.0 g/cm.sup.2 (AUL) of 8.1 g/g, a residual monomer content of 8550 ppm, an extractables content of 9.7% by weight and a moisture content of 8.5% by weight.

(26) The superabsorbent had the following particle size distribution:

(27) TABLE-US-00004 >1000 μm 0.3% by weight 850-1000 μm 1.1% by weight 600-850 μm 4.7% by weight 500-600 μm 13.9% by weight 400-500 μm 35.5% by weight 300-400 μm 34.3% by weight 250-300 μm 6.6% by weight 200-250 μm 3.1% by weight 106-200 μm 0.4% by weight <106 μm 0.1% by weight

(28) The superabsorbent had a median particle size (d50) of 397 μm and a mean sphericity (mSPHT) of 0.81.

(29) The base polymer was subsequently surface postcrosslinked analogously to examples 11 to 15 of WO 2015/110321 A1. 2.0% by weight of ethylene carbonate, 5.0% by weight of water and 0.4% by weight of aluminum sulfate were used, based in each case on the base polymer. The product temperature was 150° C. and the height of the weir was 75%.

(30) In the cooler downstream of the surface postcrosslinking, 4.7% by weight of a 0.1% by weight aqueous solution of sorbitan monolaurate was added.

(31) The superabsorbent produced had a bulk density (ASG) of 0.753 g/ml, a centrifuge retention capacity (CRC) of 46.8 g/g, an absorption under a pressure of 21.0 g/cm.sup.2 (AUL) of 33.0 g/g, an absorption under a pressure of 49.2 g/cm.sup.2 (AUHL) of 16.7 g/g, a saline flow conductivity (SFC) of 0×10.sup.−7 cm.sup.3 s/g, a vortex of 60 s, a moisture content of 4.4% by weight, a residual monomer content of 460 ppm and an extractables content of 5.0% by weight.

(32) The surface postcrosslinked superabsorbent had the following particle size distribution:

(33) TABLE-US-00005 >850 μm 0.0% by weight 710-850 μm 0.6% by weight 600-710 μm 4.5% by weight 500-600 μm 10.9% by weight 400-500 μm 40.6% by weight 300-400 μm 34.0% by weight 250-300 μm 6.1% by weight 200-250 μm 2.6% by weight 150-200 μm 0.5% by weight <150 μm 0.2% by weight

(34) The superabsorbent had a median particle size (d50) of 405 μm and a mean sphericity (mSPHT) of 0.80.

Production Example 5—Superabsorbent A

(35) A superabsorbent was produced analogously to example 2 of WO 2016/134905 A1. The monomer solution used additionally comprised 1.07% by weight of the disodium salt of 1-hydroxyethylidene-1,1-diphosphonic acid. Also used was a dropletizer plate with 645 holes, a hole diameter of 100 μm and a hole separation of 8 mm.

(36) The gas inlet temperature of reaction zone (5) was 167° C., the gas outlet temperature of reaction zone (5) was 108° C., the gas inlet temperature of the internal fluidized bed (27) was 94° C., the product temperature in the internal fluidized bed (27) was 73° C., the gas outlet temperature of the condensation column (12) was 58° C., and the gas outlet temperature of the gas drying unit (37) was 47° C.

(37) The superabsorbent produced (base polymer) had a bulk density (ASG) of 0.648 g/ml, a centrifuge retention capacity (CRC) of 54.7 g/g, an absorption under a pressure of 21.0 g/cm.sup.2 (AUL) of 8.8 g/g, a residual monomer content of 12600 ppm, an extractables content of 8.9% by weight and a moisture content of 9.0% by weight.

(38) The superabsorbent had the following particle size distribution:

(39) TABLE-US-00006 >1000 μm 0.1% by weight 850-1000 μm 0.1% by weight 600-850 μm 0.6% by weight 500-600 μm 2.6% by weight 400-500 μm 13.1% by weight 300-400 μm 41.5% by weight 250-300 μm 22.0% by weight 200-250 μm 15.0% by weight 106-200 μm 4.9% by weight <106 μm 0.1% by weight

(40) The superabsorbent had a median particle size (d50) of 284 μm and a mean sphericity (mSPHT) of 0.82.

(41) The base polymer was subsequently surface postcrosslinked analogously to examples 11 to 15 of WO 2015/110321 A1. 2.0% by weight of ethylene carbonate, 5.0% by weight of water and 0.4% by weight of aluminum sulfate were used, based in each case on the base polymer. The product temperature was 175° C. and the height of the weir was 75%.

(42) In the cooler downstream of the surface postcrosslinking, 4.7% by weight of a 0.1% by weight aqueous solution of sorbitan monolaurate was added.

(43) The superabsorbent produced had a bulk density (ASG) of 0.733 g/ml, a centrifuge retention capacity (CRC) of 28.6 g/g, an absorption under a pressure of 21.0 g/cm.sup.2 (AUL) of 29.2 g/g, an absorption under a pressure of 49.2 g/cm.sup.2 (AUHL) of 23.8 g/g, a saline flow conductivity (SFC) of 32×10.sup.−7 cm.sup.3 s/g, a vortex of 43 s, a moisture content of 3.5% by weight, a residual monomer content of 790 ppm and an extractables content of 1.5% by weight.

(44) The surface postcrosslinked superabsorbent had the following particle size distribution:

(45) TABLE-US-00007 >850 μm 0.2% by weight 710-850 μm 0.2% by weight 600-710 μm 0.9% by weight 500-600 μm 2.1% by weight 400-500 μm 13.5% by weight 300-400 μm 41.9% by weight 250-300 μm 24.2% by weight 200-250 μm 11.8% by weight 150-200 μm 4.7% by weight <150 μm 0.5% by weight

(46) The superabsorbent had a median particle size (d50) of 285 μm and a mean sphericity (mSPHT) of 0.80.

Production Example 6—Superabsorbent B

(47) A superabsorbent of the AQUA KEEP SA-60-SX-II type was used (Sumitomo Seika Chemicals Co., Ltd.; Osaka; Japan). AQUA KEEP SA-60-SX-II is a superabsorbent produced by inverse suspension polymerization.

(48) The superabsorbent had a bulk density (ASG) of 0.66 g/ml, a centrifuge retention capacity (CRC) of 34.0 g/g, an absorption under a pressure of 0.0 g/cm.sup.2 (AUNL) of 54.8 g/g, an absorption under a pressure of 21.0 g/cm.sup.2 (AUL) of 32.8 g/g, an absorption under a pressure of 49.2 g/cm.sup.2 (AUHL) of 14.7 g/g, a saline flow conductivity (SFC) of 0×10.sup.−7 cm.sup.3 s/g, a vortex of 46 s and a moisture content of 11.1% by weight.

(49) The superabsorbent had the following particle size distribution:

(50) TABLE-US-00008 >710 μm 6.5% by weight 600-710 μm 9.6% by weight 500-600 μm 16.1% by weight 400-500 μm 24.7% by weight 300-400 μm 28.2% by weight 150-300 μm 14.6% by weight 106-150 μm 0.3% by weight <106 μm 0.0% by weight

(51) The superabsorbent had a median particle size (d50) of 429 μm and a mean sphericity (mSPHT) of 0.68.

(52) Superabsorbent A and superabsorbent B were mixed in different ratios, and the superabsorbent mixtures M obtained were analyzed. The results are compiled in tables 1 to 6:

(53) TABLE-US-00009 TABLE 1 Mixtures of superabsorbent A (example 3) and superabsorbent B (example 1) Superabsorbent Superabsorbent CRC T20 VAUL Example B A g/g s s 1*) 100%   0% 44.4 >1200 2567 2*) 80% 20% 40.0 >1200 1330 3*) 60% 40% 35.8 >1200 386 4*) 40% 60% 33.0 393 243 5 20% 80% 28.5 210 179 6*)  0% 100%  26.0 165 180 *)comparative example

(54) The results of table 1 are shown in FIGS. 1 and 2.

(55) TABLE-US-00010 TABLE 2 Mixtures of superabsorbent A (example 5) and superabsorbent B (example 4) Superabsorbent Superabsorbent CRC T20 VAUL Example B A g/g s s  7*) 100%   0% 46.8 >1200 887  8*) 80% 20% 44.3 749 762  9*) 60% 40% 39.6 396 689 10*) 40% 60% 36.5 300 470 11 20% 80% 31.6 220 365 12*)  0% 100%  28.6 182 254 *)comparative example

(56) The results of table 2 are shown in FIGS. 3 and 4.

(57) TABLE-US-00011 TABLE 3 Mixtures of superabsorbent A (example 3) and superabsorbent B (example 4) Superabsorbent Superabsorbent CRC T20 VAUL Example B A g/g s s 13*) 100%   0% 46.8 >1200 887 14*) 80% 20% 41.8 563 614 15*) 60% 40% 37.6 317 422 16*) 40% 60% 32.8 228 303 17 20% 80% 28.5 187 206 18*)  0% 100%  26.0 165 180 *)comparative example

(58) The results of table 3 are shown in FIGS. 5 and 6.

(59) TABLE-US-00012 TABLE 4 Mixtures of superabsorbent A (example 5) and superabsorbent B (example 1) Superabsorbent Superabsorbent CRC T20 VAUL Example B A g/g s s 19*) 100%   0% 44.4 >1200 2567 20*) 80% 20% 41.0 >1200 1309 21*) 60% 40% 38.4 >1200 561 22*) 40% 60% 34.0 546 378 23 20% 80% 30.7 323 300 24*)  0% 100%  28.6 182 254 *)comparative example

(60) The results of table 4 are shown in FIGS. 7 and 8.

(61) TABLE-US-00013 TABLE 5 Mixtures of superabsorbent A (example 3) and superabsorbent B (example 6) Superabsorbent Superabsorbent CRC T20 VAUL Example B A g/g s s 25*) 100%   0% 34.0 >1200 1398 26*) 80% 20% 32.1 753 520 27*) 60% 40% 29.9 222 177 28*) 40% 60% 28.0 167 145 29 20% 80% 26.9 155 161 30*)  0% 100%  26.0 165 180 *)comparative example

(62) The results of table 5 are shown in FIGS. 9 and 10.

(63) TABLE-US-00014 TABLE 6 Mixtures of superabsorbent A (example 3) and superabsorbent B (example 2) Superabsorbent Superabsorbent CRC T20 VAUL Example B A g/g s s 31*) 100%   0% 33.4 285 362 32*) 80% 20% 32.6 271 323 33*) 60% 40% 29.3 217 287 34*) 40% 60% 27.6 182 192 35 20% 80% 26.1 143 163 36*)  0% 100%  26.0 165 180 *)comparative example

(64) The results of table 6 are shown in FIGS. 11 and 12.