Polycondensates of sulfonated coal tar fractions
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United States of America Patent
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May 17, 1988
Grant Date -
N/A
app pub date -
Jan 2, 1987
filing date -
Jan 2, 1987
priority date (Note) -
Expired
status (Latency Note)
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Abstract
A simpler and new process for the polycondensation of a sulfonated coal tar fraction comprising: sulfonating a coal tar fraction having a distillation range of 200.degree. to 240.degree. at normal pressure, with an excess of 20-30% mole of sulfuric acid, as opposed to 105% in the prior art, for 4-8 hours at a temperature of 160.degree. C..+-.10.degree. C. under reflux. The product is diluted with water to render it fluid at about 80.degree. C. and molar ratio of formaldehyde per mole of the sulfonated coal tar fraction is then added gradually at a temperature of about 85.degree. C..+-.5.degree. C., then gradually heated for about 1 to 4 hours at 100.degree. to 106.degree. C., and then further raised to 106.degree. C.-120.degree. C. for 2 to 4 hours. The product is then cooled and neutralized. With this process, new polycondensates with improved properties are produced. The polycondensation including neutralization is completed within 16 hours from the time the formaldehyde is added.
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