The idea of using natural products in adhesives is not new. Animal blood, fish bones or skin and casein adhesives are one of the oldest materials used as wood adhesives. They were displaced by higher performance synthetic polymers in the 1950s. However, due to cost and environmental concerns, the natural products are now regaining a prominent position in Research and Development programmes of the morte highlander technique global adhesives producers.
A primary objective is to develop new synthetic materials using natural resources as a starting point which will provide similar or enhanced properties to their petroleum-based counterparts. One of the naturally occurring polymers that is achieving significant attention is lignin. However the abundant lignin currently available as a waste product of the pulp and paper industry IS hardly of any use as its terminations have heavily damaged by the brutal cellulose extraction process named kraft and very much in use among the Pulp and Paper Industry.
Lignin is a natural low molecular weight linear phenolic polymer which has the roles of strengthing and waterproofing the cell walls of plants and trees. Its has fragile terminations attaching it to the cellulosic parts of the plant cells. In Pulp mills and biorefineries, lignin IS séparantes from the cellulosic parts, however with more or les brutal or soft extraction processes.
Lignin removed via the kraft process (sulfate pulping) is usually burned for its fuel value, providing energy to run the mill and its associated processes.
But lignin removed via soft extraction processes such as organosolv ( usine organic acids ta low température and pressure) or more recently biotech bases extraction (using enzymes) has been proven to be useable to replace petrochemicals components in adhesives, elastomers and plastics such as polyurethane. In 2012, carbon fibre could also be produced from Lignin.
At the current stage of development of soft process biorefineries, pure enough and functional lignin for these applications is not yet available in commercial quantities.
Let´s focus in this article on a very promising organosolv process developed by a French start-up company CIMV, based on a portfolio of eight patents stemming from research housed in the Ensiacet Toulouse laboratory.
The following process description comes from CIMV’s website
The CIMV process extracts and purify the three principal components of lignocellulosic biomass after cleanly separating them – with no deterioration – into three intermediary products for both chemical and biotechnology industries :
- BioligninTM (phenolic polymer )
- Cellulose and Glucose.
- Sugars syrup (monomers, dimers of xylose and other C5 sugars).
A lignin is a biopolymer that is complex to extract and hence used. CIMV is currently the only technology to market a pure, non deteriorated lignin under the BioligninTM trademark. The chemical structure was formally established for the first time by mass spectrometry and high resolution nuclear magnetic resonance. These are linear oligomers with low molecular weight, behaving exactly like homologue oligomers and phenolic polymers obtained from petrochemistry. Biolignin requires few processing stages and also serves as a raw material for manufacturing many products currently made from refining and oil processing.
The advantages of CIMV BioligninTM :
- Direct substitute for phenol in most of its industrial applications (REACH Directive).
- Massive reduction in greenhouse gas emissions: direct substitute for petroleum-based products.
- Product that industry can use directly.
- Perfectly defined base product.
CIMV BioligninTM commercial applications :
Glues with no formaldehyde or phenol: fibreboards, laminates and plywoods. Green plastics industry: polyurethanes, polyesters, phenolic resins, epoxy resins. As a matter of fact CIMV has initiated a full range aof application development programs in collaborative partnership with end-users industries such as wood panel manufacturers and epoxy resin manufacturers . This applicative research has proven that CIMV´s Biolignin* from its pilot biorefinery in France could replace petrochemicals phenol in phenol-formaldhehyde adhesive blends.