Patent GB-693760-A (GB)
Title: Improvements relating to methods for the preparation of fusible lignin resins
IPC: C08H5/02
Filed: 1950-05-31
Abstract: Lignin resins are prepared from lignin or lignin containing material (e.g. wood-hydrolysis lignin, lignin sulphonic acid, sulphite waste liquor, peat or lignite, or mixtures of these materials) by heating with alkali hydroxide solution at above 100 DEG  C. to dryness, dissolving the dried material in water. and precipitating lignin resin from the solution by acidification thereof.  The alkali hydroxide solution used may be a solution of alkali hydroxide in sulphite cellulose waste liquor.  The alkali hydroxide may be replaced in part by alkali carbonate or alkaline earth oxides and the heating may be carried out in presence of phenols, amines or monohydric or polyhydric alcohols.  The precipitation may be by strong mineral acids or weak acids (e.g. CO2 or SO2).  The liquid remaining after precipitation by weak acids may be (a) causticized with slaked lime, filtered from insoluble calcium salts and heated to dryness with further lignin; (b) treated with mineral acid to precipitate any remaining lignin; (c) evaporated, causticized with slaked lime, and heated with further lignin to dryness; (d) causticized with slaked lime, heated to dryness with further lignin dissolved in water and the liquor remaining after precipitation of the lignin resin roasted, causticized and then heated with further lignin to dryness.  The precipitated lignin may be mixed with lignin-dissolving materials, e.g. monohydric or polyhydric alcohols (e.g. glycols or glycerine), esters (e.g. glycerine esters), ethers or ketones or with the condensable components of synthetic resins, e.g. phenols, amines, amides, aldehydes (e.g. hexamethylene tetramine, formaldehyde, acetaldehyde or furfural) or the condensates produced therefrom.  The lignin resins may be used in the manufacture of moulding compounds, ply-wood, laminated wood board or board formed from wood chips.  In examples: (1) Wood hydrolysis lignin is heated with aqueous sodium hydroxide to dryness, the product dissolved in water and lignin precipitated by sulphuric acid.  The lignin is fused by heating and is worked into a suspension with water which is heated to boiling-point.  The lignin may then be heated with an alkali condensed phenol-formaldehyde resin or mixed with glycerine, sodium hydroxide, water, wood meal and kaolin to form a moulding composition.  (2) Wood hydrolysis lignin is heated with a sodium hydroxide solution to dryness and lignin resin precipitated with carbonic acid.  This resin is suspended in water, sulphuric acid added and the solution treated with slaked lime, filtered from precipitated calcium carbonate and heated to dryness with wood hydrolysis lignin after addition of sodium hydroxide.  (3) Lignin resin obtained as in (2) is treated with mineral acid and the remaining liquor evaporated in vacuo and roasted, the salt deposit taken up with water, calcium oxide added and the alkaline liquor obtained after filtration heated with wood hydrolysis lignin after addition of sodium hydroxide.  (4) Lignin obtained by wood hydrolysis with sulphuric acid is heated to dryness with aqueous sodium hydroxide and phenol.  The dried product is dissolved in water and lignin precipitated with a mineral acid.  The product may be worked up as in example (1).  (5) A mixture of peat, sodium hydroxide solution and sulphite waste liquor is heated to dryness and the product dissolved in water which is saturated with sulphur dioxide to precipitate lignin resin.  This resin is suspended in water, sulphuric acid added and the lignin resin is precipitated by heating. (6) Sulphite waste liquor is heated with sodium hydroxide solution to dryness and the product dissolved in water from which lignin is precipitated by sulphurous acid.  The product is suspended in water which is acidified and the lignin resin fused.ALSO:Lignin resins are prepared from lignin or lignin-containing material (e.g. wood-hydrolysis lignin, lignin sulphonic acid, sulphite waste liquor, peat or lignite, or mixtures of these materials) by heating with alkali hydroxide solution at above 100 DEG  C. to dryness, dissolving the dried material in water, and precipitating lignin resin from the solution by acidification thereof.  The alkali hydroxide solution used may be a solution of alkali hydroxide in sulphite cellulose waste liquor.  The alkali hydroxide may be replaced in part by alkali carbonate or alkaline earth oxides and the heating may be carried out in presence of phenols, amines or monohydric or polyhydric alcohols. The precipitation may be by strong mineral acids or weak acids (e.g. CO2 or SO2).  The liquid remaining after precipitation by weak acids may be (a) causticized with slaked lime, filtered from insoluble calcium salts and heated to dryness with further lignin; (b) treated with mineral acid to precipitate any remaining lignin; (c) evaporated, causticized with slaked lime and heated with further lignin to dryness; (d) causticized with slaked lime, heated to dryness with further lignin dissolved in water and the liquor remaining after precipitation of the lignin resin roasted, causticized and then heated with further lignin to dryness.  The precipitated lignin may be mixed with lignin-dissolving materials, e.g. monohydric or polyhydric alcohols (e.g. glycols or glycerine), esters (e.g. glycerine esters), ethers or ketones or condensable components of synthetic resins, e.g. phenols, amines, amides, aldehydes, ketones, or the condensates produced therefrom. The lignin resins may be used in the manufacture of moulding compounds, ply-wood, laminated wood board or board formed from wood chips.  In examples: (1) wood hydrolysis lignin is heated with aqueous sodium hydroxide to dryness, the product dissolved in water and lignin precipitated by sulphuric acid.  The lignin is fused by heating and is worked into a suspension with water which is heated to boiling-point.  The lignin may then be heated with an alkali condensed phenol formaldehyde resin or mixed with glycerine, sodium hydroxide, water, wood meal and kaolin to form a moulding composition.  (2) Wood hydrolysis lignin is heated with a sodium hydroxide solution to dryness and lignin resin precipitated with carbonic acid.  This resin is suspended in water, sulphuric acid added and the solution treated with slaked lime, filtered from precipitated calcium carbonate and heated to dryness with wood hydrolysis lignin after addition of sodium hydroxide.  (3) Lignin resin obtained as in (2) is treated with mineral acid and the remaining liquor evaporated in vacuo and roasted, the salt deposit taken up with water, calcium oxide added and the alkaline liquor obtained after filtration heated with wood hydrolysis lignin after addition of sodium hydroxide.  (4) Lignin obtained by wood hydrolysis with sulphuric acid is heated to dryness with aqueous sodium hydroxide and phenol.  The dried product is dissolved in water and lignin precipitated with a mineral acid.  The product may be worked up as in example (1). (5) A mixture of peat, sodium hydroxide solution and sulphite waste liquor is heated to dryness and the product dissolved in water which is saturated with sulphur dioxide to precipitate lignin resin.  This resin is suspended in water, sulphuric acid added and the lignin resin is precipitated by heating. (6) Sulphite waste liquor is heated with sodium hydroxide solution to dryness and the product dissolved in water from which lignin is precipitated by sulphurous acid.  The product is suspended in water which is acidified and the lignin resin fused.