| 摘要 |
A process of stabilizing a polymeric N-vinyl pyrrolidone against discoloration comprises incorporating with said pyrrolidone 0.01 to 0.5 per cent by weight of a hydrazine having the general formul R-NH.NH2, R1NHNHR, R1R1N.NHR, R2CX.NHNH2 or R.CONHNH. CO.R2 wherein R is hydrogen or an alkyl, hydroxyalkyl or ammonium alkanoate radical, R1 represents an alkyl, hydroxyalkyl or an ammonium alkanoate radical, R2 represents NH2 or an alkyl radical and X represents oxygen or sulphur. The polymer may be a homopolymer of N-vinyl pyrrolidone (which may have methyl or ethyl ring substituents), or a grafted polymer wherein the water-soluble component is a polymer of N-vinyl pyrrolidone, a copolymer containing -CHX-CH2- units, where X is halogen, carbalkoxy, cyano, acyloxy, aryl, alkoxy or phenoxy. A number of derivatives of hydrazine, semicarbazide and thiosemicarbazide within the scope of the above formul are listed. In examples: (1) portions of an aqueous solution of polymeric N-vinyl pyrrolidone are heated alone and in admixture with hydrazine, b -hydroxyethyl hydrazine, the ammonium salt of hydrazinodiacetic acid and acetyl hydrazine respectively, and the light transmission of the solutions at various stages is determined; (4) aqueous polymeric N-vinyl pyrrolidone containing dimethylhydrazine is spray-dried; (7) a 7 per cent solution of a copolymer of acrylonitrile and N-vinyl-pyrrolidone in an aqueous mixture of zinc and magnesium chlorides and hydrazine is spun into filaments in a coagulating bath; (8) a grafted copolymer of acrylonitrile and polymeric N-vinyl-pyrrolidone prepared according to Example (17) of Specification 715,194 is dissolved in dimethyl formamide containing 2-hydroxy-ethyl hydrazine and is spun into filaments. |
