Novel Superabsorbents and the Method(s) of Obtaining the Same

• US 20130069000A1
• Filed: 06/29/2011
• Published: 03/21/2013
• Est. Priority Date: 07/02/2010
• Status: Active Grant

• Current Assignee: Indian Council of Agricultural Research (Government of India)
• Original Assignee: Indian Council of Agricultural Research (Government of India)
• Inventors: Anupama, Sarkar, Dhrugba Jyoti, Parmar, Balraj Singh
• Granted Patent: US 9,833,767 B2
• Time in Patent Office: Days
• US Class Current: 252/194
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: B01J 20/267 Cross-linked polymers
• CPC Class Codes: B01J 20/3028 Granulating, agglomerating or aggregating
• CPC Class Codes: C08F 220/56 Acrylamide; Methacrylamide
• CPC Class Codes: C08F 222/385 Monomers containing two or more (meth)acrylamide groups, e.g. N,N'-methylenebisacrylamide
• CPC Class Codes: C08F 251/00 Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
• CPC Class Codes: C08F 292/00 Macromolecular compounds obtained by polymerising monomers on to inorganic materials
• CPC Class Codes: C09K 17/40 containing mixtures of inorganic and organic compounds

Abstract

This invention relates to novel non-composite and composite superabsorbents, wherein the dry superabsorbents are xerogels, more particularly the bio-xerogels or the composites, particularly the biocomposites, more particularly the bionanocomposites and the method(s) of obtaining the same characterized by simultaneous in situ grafting and cross linking of ethylinically unsaturated monomers on to a single biopolymer of plant or animal origin, or on combination of different biopolymers or biopolymer(s) or/and clay(s), in a homogeneous polar phase, in the presence of initiator and crosslinker of chemical or non-chemical origin, at a temperature of 40 to 90° C., achieved by conventional or microwave heating, reaction time varying from instantaneous to 48 hours, involving use of alkali, either in situ or post reaction at room or elevated temperatures for achieving superior absorbency, in an inert or ambient reaction environment, to yield a neutral or near neutral product.

Claims

1-25. -25. (canceled)

26. Non-composite and composite superabsorbents comprising 3 to 85% of ethylinically unsaturated monomers cross linked on to a combination of biopolymers or single biopolymer with at least one inorganic filler in a homogeneous polar phase in presence of 0.005 to 6.5% of a chemical initiator or a non chemical initiator and a chemical cross linker.

27. The non-composite and composite superabsorbents as claimed in claim 26, wherein the unsaturated monomer is selected from acrylamide, acrylonitrile, acrylamido-propane sulfonic acid, acrylic acid, acrylate, or N-vinyl pyrrolidone in an amount of 10 to 70% of the mass of the backbone of the biopolymer.

28. The non-composite and composite superabsorbents as claimed in claim 26, wherein the biopolymer is selected from Sterculia urens, Cochlospermum religiosum, guar gum, tragacanth gum, Acacia gum, cellulose, modified cellulose, starch, modified starch, alginic acid and/or its derivatives, or combinations thereof.

29. The non-composite and composite superabsorbents as claimed in claim 26, wherein the at least one inorganic filler comprises a clay selected from kaolinite, halloysite, endalite, montmorillonite, beidellite, nontronite, talc, mica, vermiculite, illite, bentonite, chlorite or combinations thereof.

30. The non-composite and composite superabsorbents as claimed in claim 26, wherein the combination of biopolymers are prepared in the ratio of 80:

20 of a first biopolymer to a second biopolymer.

31. The non-composite and composite superabsorbents as claimed in claim 26, wherein the combination of biopolymers and the at least one inorganic filler are prepared in the ratio of 99:

1 to 1;

99.

32. The non-composite and composite superabsorbents as claimed in claim 26, wherein the chemical initiator comprises a polar solvent, wherein the polar solvent is selected from water soluble persulfates, peroxides, ammonium cerric nitrate, azo compounds, or combinations thereof.

33. The non-composite and composite superabsorbents as claimed in claim 26, wherein the non chemical initiator comprises electromagnetic radiation applied over a period of 0 to 24 hours, wherein the electromagnetic energy is selected from gamma rays and high energy ultraviolet rays.

34. The non-composite and composite superabsorbents as claimed in claim 26, wherein cross linking is carried out in the presence of either of bisacrylamide, glutaraldehyde, adipic acid, dihydrazide, or combinations thereof at a concentration of 0.05 to 10% mass by mass basis of the total reaction mass.

35. The non-composite and composite superabsorbents as claimed in claim 26, wherein homogenization of the backbone of the biopolymer, inorganic filler, monomer, initiator, and cross linker is achieved in a polar solvent selected from water, methanol, ethanol, propanol, or combinations thereof.

37. The superabsorbents as claimed in claim 26, for use in diverse fluid absorption and/or release situations such as in agriculture, medical, sanitary products, cosmetics and others, particularly the agricultural applications.

38. The non-composite and composite superabsorbents as claimed in claim 26, wherein the combination of biopolymers are prepared in a ratio of 50:

50 of a first biopolymer to a second biopolymer.

39. The non-composite and composite superabsorbents as claimed in claim 26, wherein the combination of biopolymers and the at least one inorganic filler are prepared in a ratio of 90:

10 to 10;

90.

40. The non-composite and composite superabsorbents as claimed in claim 29, wherein the at least one inorganic filler comprises a combination of at least two clays, a clay and zeolite, or a clay and carbonaceous materials, wherein the carbonaceous materials are selected from ash derived from wheat, ash derived from rice husk, biochar derived from sugarcane molasses, or combinations thereof.

41. The non-composite and composite superabsorbents as claimed in claim 32, wherein the chemical initiator further comprises a co-initiator at a concentration of 0.01 to 5%, on mass by mass basis of total reaction mass.

42. The non-composite and composite superabsorbents as claimed in claim 35, wherein homogenization of the backbone of the biopolymer, inorganic filler, monomer, initiator, and cross linker is achieved in pure water alone at 5 to 20 times the mass at a temperature of 25 to 90°

C.

43. The non-composite and composite superabsorbents as claimed in claim 35, wherein homogenization of the backbone of the biopolymer, inorganic filler, monomer, initiator, and cross linker is achieved through irradiation in a microwave oven for a period of 2 seconds to five minutes.

36. A method for producing composite and non-composite superabsorbents comprising:

grafting and cross linking in situ of ethylinically unsaturated monomers on to a combination of biopolymers or single biopolymer of plant or chemical and/or with at least one inorganic filler in a homogeneous polar phase, in presence of a chemical initiator, a temperature range of 40-90°

C. or a non chemical initiator, and a cross linker;

adding alkali in situ at room temperatures;

removing the excess alkali to achieve a neutral pH of a finished product;

subjecting the finished product to dehydration, and drying; and

pulverizing the final product to a desired particle size.

44. The method of claim 36, wherein the step of adding alkali comprises adding alkali subsequent to the reaction at room temperatures.

45. A non-composite and composite superabsorbents prepared from a composition comprising 3 to 85% of ethylinically unsaturated monomers cross linked on to a combination of biopolymers or single biopolymer with at least one inorganic filler in a homogeneous polar phase in presence of 0.005 to 6.5% of a chemical initiator or a non chemical initiator and a chemical cross linker.