Polymer made of lignin, and method for making it

A method for producing a three-dimensional aromatic nuclei-containing, sulfur-containing polymer derived from lignin and exhibiting a weight loss of less than 10% when heated to 200.degree. C for 1/2 hour in an inert gas, said method comprising:

• heating, in a homogeneous reaction mixture, at least one lignin preparation which is a member of the group consisting of thioglycolic acid-lignin, sulfate-lignin, alkali-lignin, lignosulfonic acid, hydrolysis lignin, chlorinated lignin, ammonium-, alkali-, and alkaline-earth salts of said lignins and lignosulfonic acid, sulfite and sulfate pulp liquor from which carbohydrates have been removed, and lignin degradation products having a suitable activating substituent
• with
• at least one member of the group consisting of sulfur and a sulfur-containing compound from the group consisting of inorganic sulfides, mercaptans, thioepoxides, thioketones, organic sulfides, disulfides, and sulfur-containing lignin degradation products or mixtures thereof, the amount of elemental sulfur or the sulfur in said sulfur-containing compound comprising from 10-200% by weight of said lignin preparation, at a temperature of about 190.degree.-350.degree. C, for a time sufficient to form the polymer but not longer than 20 hours, wherein the hydrogen atoms of the aromatic rings of the phenyl propane units of lignin or of the conversion products of the phenyl propane units of lignin are partially or completely substituted by thioether bonds.