Surface cross-linked superabsorbent polymer particles and methods of making them

US007871640B2

(12) Ullltfild States P2116111 (10) Patent N0.: US 7,871,640 B2 Flohr et al. (45) Date of Patent: *Jan. 18, 2011 (54) SURFACE CROSS-LINKED 3,959,569 A 5/1976 Burkholder, Jr. et al. SUPERABSORBENT POLYMER PARTICLES 4,062,817 A 12/1977 Westerman AND METHODS OF MAKING THEM 4,076,663 A 2/1978 Masuda et al. 4,093,776 A 6/1978 Aoki et al. (75) Inventors: Andreas Flohr, Kronberg (DE); Torsten i 1 L"l°l“°rA Kmllbelg (DE) 4 567 525 A 1/1983 Kitamura . 4,389,513 A 6/1983 M' aki (73) Assignee: The Procter & Gamble Company, 4,446,261 A 5/1984 Yelmlzeele et ele C111°11111a11, 911013) 4,610,678 A 9/1986 Weisman et 3.1. ( * ) Notice: Subject to any disclaimer, the term of this (C011111111e(1) patent is extended or adjusted under 35 U.S.C. 154(6) by 0 days. FOREIGN PATENT DOCUMENTS EP 0 246 848 A 11/1987 This patent is subject to a terminal dis- _ Ciaimen (Continued) OTHER PUBLICATIONS (21) Appl.No.: 12/537,585 Y. Tang, R.P. Thorn, R.L. Mauldin III, P.H. Wine, Kinetics And (22) Filed; Aug, 7, 2009 Spectroscopy Of the SO4-Radical in Aqueous Solution, Journal of Photochemistry and Photobiology, A: Chemistry, 44(1988), pp. 243(65) Pi-inf Publication Data 258, Elsevier Sequoia/Printed in The Netherlands. US 2009/0299315 A1 Dec. 3, 2009 (C011111111e<1) (51) Int CL Iirimjry Exami1ner—Sus1an WBIenr1nnaei} P H A61L 15/00 (200601) ( ) ttorney, gent, or Irm— o . owe (52) U.S. Cl. ..................... .. 424/443; 424/445; 424/489; 57 ABSTRACT 522/40; 522/41; 522/42; 522/43; 522/46; ( ) 522/l 17A 522/121 Superabsorbent polymer particles with improved surface (58) Field of Classification Search ............... .. 424/443, emssqinking and their nse in absorbent en~ne1es_ The super424/489, 445; 522/88, 121, 129, 40, 41, absorbent polymer particles comprise polymer chain seg522/42, 43, 44, 46, 117; 525/329-1; 526/316; ments, wherein at least a part ofthe polymer chain segments 428/500 are covalently cross-linked to each other and wherein at least See aPP11Ca11O11 file for Complete Search h151O1'Y~ a part of the cross-links include the reaction product of cross(56) R efer en e e S Cit e d linking molecules having at least two C:C double bonds and

further include the reaction product of radical former molecules. These cross-links are present at surfaces of the superabsorbent polymer particles.

11 Claims, 2 Drawing Sheets

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