Patent EA-002495-B1 (EA)
Title: Method of preparation of products which absorb water intermolecularly
Inventor: VALKANAS GEORGE N
IPC: C08F8/00
Filed: 1998-10-23
Abstract: 1. Method for the preparation of a particulate, stable macroplegmatic polymer product, capable of intermolecularly absorbing about 100 to 300 times its weight of water, said method comprising the steps of: (i) subjecting a polymer having aromatic groups, in a form of a 10-30% solution in chlorinated solvent(s), to a crosslinking reaction with 2,5-dichloromethyl-1,4-dimethylbenzene, to obtain an insoluble macroplegmatic gel; (ii) extruding and cutting said insoluble macroplegmatic gel to obtain discrete macroplegmatic gel particles of a main dimension of 3 to 5 centimeters; (iii) reacting said macroplegmatic gel particles, suspended in chlorinated solvent(s), with strong acidic agent(s) to introduce anionic groups in a high density and obtain highly anionic macroplegmatic gel particles. 2. Method according to claim 1, wherein subjecting said highly anionic macroplegmatic gel particles to a work-up procedure comprising removing solvent(s) by vacuum distillation, washing with methanol or ethanol, neutralizing in about 30% aqueous sodium or potassium hydroxide, shrinking/dehydrating in 15-25% aqeous sodium chloride to a water content of about 10%, and deodorizing by heating under vacuum in a temperature up to about 160 degree C. 3. Method according to claim 2 wherein said shrinking/dehydration in (iv) is carried out by subjecting said highly anionic macroplegmatic gel particles to an electric field of 20V. 4. Method according to claim 1, wherein said polymer having aromatic groups is selected from the group comprising polystyrene, hydrogenated styrene butadiene rubber (SBR), styrene-acrylonitrile copolymers and mixtures and/or copolymers thereof. 5. Method according to claim 1, wherein said crosslinking reaction in (i) is carried out in a melt of said polymer. 6. Method according to claim 1, wherein said reaction in (i) is carried out in a temperature ranging from room temperature to about 50 degree C and optionally using, as further catalysts, SbCl5 and/or TiCl4, in catalytically effective amounts. 7. Method according to claim 1, wherein said sulfonating agent(s) being selected from chlorosulfonic acid, suflur trioxide or oleum sulfuric acid, each in amolar ratio of equivalent suflur trioxide of 1,5-2,2 mol per mol of aromatic groups contained in said insoluble macroplegmatic gel particles and any nitration agent is nitric acid. 8. Method according to claim 7 wherein said reaction with sulfonating agent(s) produces further crosslinking of said macroplegmatic gel particles, through the formation of sulphone bridges, said further crosslinking being controlled with the addition of acetic acid as a crosslinking inhibitor in a proportion of 10-15%. 9. Method according to claims 4 and 7, wherein in the case that said polymer having aromatic groups comprises styrene-acrylonitrile copolymer(s), then carboxylic groups are formed as additional anionic groups, from the hydrolysis of cyano groups in the sulfonation reaction conditions. 10. Method according to claim 1 wherein said extrusion is carried out by pressing said macroplegmatic gel through an extruder comprising an array of parallel tubes of length of about 1 meter and diameter of about 3 to 4 centimeters and a cutting system at one end of the tubes, to form said particles. 11. A stable product obtained according to any of the preceding claims, which is mixed with a soil to act constantly as humidity regulator and fertility promoter thereof.