Novolac phenolic resins, process of synthesis of said phenolic resins and use thereof

Phenolic resin synthesis process, characterized in that it comprises the steps of:

• a) dissolving lignin in phenol, at a variable temperature ranging from 25 to 150° C.;
• b) adjusting pH to a variable range from 0 to 2.0;
• c) adding aldehyde, at a variable temperature ranging from 40 to 70° C.;
• d) adjusting the temperature to a variable range from 95 to 105° C., to start reflux at atmospheric pressure;
• e) optionally adding aldehyde, under reflux;
• f) condensing the obtained product, still under reflux, at a preferred temperature of 100° C., until an amount of less than 1.0% of free aldehyde is present in the reflux water;
• g) distilling the obtained product under atmospheric pressure and at a variable temperature ranging from 100 to 200° C.;
• h) applying a vacuum of, at least, 500 mmHg to the obtained product at a temperature ranging from 150 to 200° C.;
• i) solidifying the obtained product at room temperature;
• and
• j) adding a curing agent to the product of step (i).