High residual content (HRC) kraft/soda lignin as an ingredient in wood adhesives

Abstract

Most processes currently being proposed and/or used for the production of lignin from kraft or soda black liquors are capable of producing two main types of lignin: high residual content (HRC) lignin and low residual content (LRC) lignin. Surprisingly, it was discovered that HRC lignin, is a suitable ingredient in alkaline adhesives, particularly wood adhesives of the phenolic type (e.g. resole resins). This biomaterial is environmentally green and remarkably low cost, which makes it an industrially viable material to be used as a novel and major ingredient in phenolic adhesives for the manufacture of exterior grade plywood, laminated veneer lumber, oriented strand board (OSB) and other wood products—this was successfully demonstrated in a number of laboratory experiments as well as several different mill trials. The composition, preparation and application of such wood adhesives are hereby disclosed.

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