Rigid Foams Containing Lignin

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

Part of a typical lignin structure

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Renewable Polyols from “Distillers Grains”

Title: PRODUCTION OF POLYOLS USING DISTILLERS GRAINS AND PROTEINS AND LIGNIN EXTRACTED FROM DISTILLERS GRAINS

 Number/Link: US2014/200324

Applicant/Assignee: EMGPI PROC and PITTSBURG STATE UNIVERSITY 

Publication date: 17-07-2014

Gist”: Dried distillers grains are transamidated and then alkoxylated to form a polyol useful for rigid polyurethane spray foams.

Why it is interesting: ‘Distillers grains’ are a by-product of ethanol production and are currently avaible in huge quatities due to the state-sponsored bio-ethanol production in the US.  Most of the product is used as animal feeds because of the high levels of nutrients. Dried distillers grain (DDGS) contains about 30% protein, about 30% fibers (cellulose, hemicellulose and lignin) and about 30% lipids, ash and water. According to this invention DDGS can be turned into polyols by first reacting the (solid) DDGS with diethanolamine at elevated temperature and pressure (about 200°C and 3.5 MPa) and breaking down the proteins in amino-amides. The resulting liquid can subsequentlly be epoxidized with propylene oxide resulting in a polyol which is supposedly highly reactive and useful for polyurethane rigid spray foams.
Personally I find it hard to believe that a decent reproducible foam can be made with such a horrible mixture.

Transamidation of protein with subsequent epoxidation.

Transamidation of protein with subsequent epoxidation.

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