| 摘要 |
<p>Lignin is obtained in a depolymerized, soluble form from various hardwoods such as aspen by a process in which the hardwood in divided form is cooked with steam at carefully selected combinations of temperature and time, within the range 170-240.degree.C and 2-80 minutes, and then solvent extracting the cooked wood material. It has been found that lignin undergoes a depolymerization reaction in situ in the hardwood on steam cooking, followed by a condensation and possible repolymerization reaction. The process of the present invention conducts the depolymerization reaction but substantially prevents the subsequent condensation reactions, by careful choice of time and temperature cooking conditions. The lignin so obtained in depolymerized form is useful as a chemical raw material.</p> |
