GB593735A - Improvements in or relating to the formation of aliphatic carboxylic acid esters of lignin material - Google Patents

Abstract

Lignin esters are produced by treating a solution of lignin in an organic solvent or solvent mixture in the presence of an organic base (which may be the solvent) with an aliphatic carboxylic acid halide or anhydride under anhydrous conditions. In examples, lignin dissolved in pyridine with or without dioxane is heated with acetic anhydride and caproyl, lauroyl, stearoyl and oleyl chlorides respectively. Up to five hydroxyl groups may be esterified. The crude ester may be purified by dissolving in a solvent and pouring into a solvent for impurities which is a non-solvent for the ester. Thus, the myristic penta-ester may be dissolved in ether and the solution poured into methanol which precipitates the purified ester; the process, however, converts the pentato the tetra-ester. A table is given showing the properties of a large number of esters. The esters are useful as internal mould lubricants, especially for powders containing wood fibre, either alone or with resins or modifying agents, and for thermoplastic and thermosetting compositions, such as phenolformaldehyde resin compositions.ALSO:Resinous lignin esters, in which the hydroxy groups of the lignin are esterified with aliphatic monobasic carboxylic acids are used as binders, plasticizers and internal lubricants in moulding compositions, particularly those containing woody material. Examples of lignin esters specified are: the acetate, butyrate, valerate, decanate, laurate, myristate, palmitate, stearate and oleate.