| 摘要 |
<p>1305664 Cation-exchange resins ASAHI KASEI KOGYO KK 19 April 1971 [17 Feb 1970] 21371/71 Heading C3P Potassium-selective cation-exchange resins are obtained by subjecting either a styrene/ ethyl vinyl benzene/divinyl benzene copolymer or an ethyl vinyl benzene/divinyl benzene copolymer, said copolymer containing 12-60 wt. per cent divinyl benzene and being cross-linked thereby, to (1) sulphonation at 0-50‹ C., followed by (2) nitration at 0-50‹ C., the nitration being effected by either a nitric acid/ sulphuric acid or a nitric acid/acetic acid mixture in which the weight ratio of nitric acid to sulphuric or acetic acid is in the range 1 :10 to 1:1.</p> |
