| 摘要 |
1414918 Sequestering agents CIBA-GEIGY (UK) Ltd 4 Feb 1974 [14 Feb 1973] 7181/73 Heading C1C [Also in Division C7] Water is treated to inhibit scale deposition by addition thereto of a hydrolysed copolymer of maleic anhydride with a mono-ethylenically unsaturated monomer or monomer mixture, the molar ratio maleic anhydride : other monomers being from 2À5 : 1 to 100 : 1 and the copolymer M.W. being up to 1000. Said monomer may be acrylic acid, methacrylic acid, crotonic acid, itaconic acid, aconitic acid (esters), itaconic anhydride ethyl acrylate, methyl methacrylate, acrylonitrile, acrylamide, vinyl acetate, styrene, α-methyl styrene, methyl vinyl ketone, acrolein, ethylene, and/or propylene. The polymer may be hydrolyzed by water, acid or alkali; 0À1- 100 p.p.m. is added to water in a boiler or seawater evaporator, e.g. of metal such as A1 or brass. A dispersing or threshold agent may be added, e.g. polyacrylic acid (salt), hydrolysed polyacrylonitrile, polymethacrylic acid, polyacrylamide or its acrylic or methacrylic copolymers, lignin sulphonic acid, tannin, naphthalene sulphonic acid/HCHO, starch, or carboxymethylcellulose, polymaleic acid, alkyl- or amino alkyl-phosphonic acid or alkali metal phosphate. There may also be added a precipitating agent, e.g. alkali metal orthophosphate, carbonate, hydroxide, oxygen-scavengers. such as a.m. sulphite or N 2 H 4 , sequestering agents such as NTA or EDTA, corrosion inhibitors such as cyclohexylamine, morpholine, distearylamine/ethylene oxide, stearylamine, Na 2 SO 4 , MgSO 4 , or antifoaming agents, e.g. distearyl sebacamide, or adipamide, fatty alcohols or their ethylene oxide condensates. |
