| 摘要 |
<P>PROBLEM TO BE SOLVED: To make a further improvement and stabilization of paper strengthening performance of an acrylamide-based paper strengthening agent having a branched structure. Ž<P>SOLUTION: The paper strengthening agent is composed of an aqueous solution of an amphoteric acrylamide polymer. In an elution curve of differential refraction as determined by GPC (gel permeation chromatography) analysis, the amphoteric acrylamide polymer has an area ratio (s1/S) of an area (s1) partitioned by the elution curve of differential refraction and a straight line indicating a signal strength of 40 parallel to a baseline in the case when a baseline is 0 and a signal strength of the peak top of the elution curve of differential refraction is 100 to the entire area (S) partitioned by the elution curve of differential refraction and the baseline; and an area ratio (s2/S) of an area (s2) partitioned by the elution curve of differential refraction and a straight line indicating a signal strength of 60 parallel to the baseline to the entire area (S), each of which satisfies the following conditions (1) and (2), respectively: (1) the area ratio (s1/S)≥0.4 and (2) the area ratio (s2/S)≥0.2. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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