Title: PROCESS FOR THE PREPARATION OF LIGNIN BASED POLYURETHANE PRODUCTS

 Number/Link: WO2015/021541

Applicant/Assignee: Enerlab 2000

Publication date: 19-02-2015

“Gist”: Dried lignin is mixed with isocyanate before being reacted with a rigid polyol and HFC blowing agent to make rigid foams

Why it is interesting: Lignin is a cheap and abundantly available hydroxy-functional biopolymer and it is no surprise that many attempts are being made to incorporate it into polyurethane materials. This case claims that lignins, dried to a moisture content of (preferably) less than 1% (0.5% in the examples), can be mixed with isocyanates to form a relatively stable mixture with a decent potlife. The mixture can then be used to make polyurethane materials.  In the examples HFC-blown rigid PU and PIR foams are shown containing about 20% of dried lignin and with densities ranging between about 30 to 40 kg/m³.  Interesting development, however claim 41, which states that elastomers and even TPUs can be made with mixtures, is clearly over the top in my opinion.

Part of a typical lignin structure