Organosolv Lignin-Modified Phenolic Resins

Abstract

Organosolv wheat straw lignin extracted using the CIMV process TM is a linear, low molecular weight, and natural phenolic oligomer. In this study, organosolv wheat straw lignin was tested as a substitute for 50% to 70% of the phenol in a phenol-formaldehyde-resol resin. The lignin was used without any chemical modification in a one-step synthesis reaction. Parameters such as reaction time and formaldehyde-to-phenol sources (phenol + lignin) mass ratios were optimized to achieve the requirements for industrial wood adhesives in terms of pH, viscosity, and dry matter. For the first time, the formaldehyde ratio was studied in order to reduce resin residual free formaldehyde below 1%. Lignin-phenol-formaldehyde resins were successfully synthesized up to a phenol substitution rate of 70% and showed physico-chemical properties close to standard phenol-formaldehyde resins. The thermo-mechanical properties analyzed in dynamic load thermo mechanical analysis were similar to those of the reference resins. Plywood panels manufactured using these lignin-based resins reached the specifications for industrial panels according to the French standard for exterior plywood panels. Moreover, the formaldehyde content of these plywoods was low enough to satisfy even the most rigorous legislation.

Lignin Behavior During the Autocatalyzed Methanol Pulping of Eucalyptus globulus Changes in Molecular Weight and Functionality

“…Therefore, the control of pulping conditions in order to obtain lignin with the desired properties can be of interest. In this case the high functional group content and the low content of impurity (particularly sugars and extractives) of organosolv lignins could result in higher reactivity towards formaldehyde, which would compensate for its low molecular weight (Cook and Sellers 1989;Sellers et al 1994). A high functionality means a higher chemical reactivity, which can be desirable for most applications.…”

High value‐added monomer chemicals and functional bio‐based materials derived from polymeric components of lignocellulose by organosolv fractionation

“…Softwood lignin is advantageous for the production of lignin phenol resins over hardwoods and herbaceous lignins, because it has a higher guaiacol unit content, and guaiacol units are more active than syringyl units . In the 1980s, red oak organosolv lignin could be used to replace 35% to 40% of the phenol (or phenolic resin solids) in phenol‐formaldehyde resins for bonding southern pine flake boards . The use of 20% organosolv lignin as a partial replacement for producing phenolic resins was once successfully implemented by North American manufacturers of automotive for brake pads and moldings .…”

Utilization of Lignin Modified by Brown-Rot Fungi. I. Properties of Flakeboard Produced with a Brown-rotted Lignin Modified Phenolic Adhesive

“…Based on the observed BRL-formaldehyde reactivity and the experience gained through previous work with organosolv-PF resin Seilers 1989), a PFresiri at a 35% (in weight) BRL Substitution of phenol was formulated (Table 2). For comparison, a typical PFflakeboard-type resin with a 2.5:1 formaldehyderphenol mole ratio was also formulated .…”