Lignosulphonate modified ketonic resins

Abstract

PurposeThe purpose of this paper is to describe how lignosulphonate modified ketone formaldehyde resins containing functional groups such as hydroxyl, carbonyl, phenol, were produced via in situ modification of ketone/formaldehyde resins. Cyclohexanone‐formaldehyde (CF‐R), acetophenone‐formaldehyde (AF‐R) and methyl ethyl ketone‐formaldehyde (MEKFR) resins were in situ modified with lignosulphonate in the presence of sodium hydroxide. The paper reports the synthesis of lignosulphonate‐modified resins with a one step method of in situ modification of ketonic resin. The roles of the types of the ketone, lignosulphonate concentration, the solubility, molecular weight and thermal properties of the product were investigated.Design/methodology/approachKetone, formalin (37 per cent aqueous solution), lignosulphonate were mixed and 20 per cent aqueous NaOH solution was added to produce the resin.FindingsThere was improvement of the properties of the lignosulphonate modified ketonic resins produced from waste black liquor. The lignosulphonate modified ketone‐formaldehyde resins were soluble in common organic solvents.Research limitations/implicationsThe reaction mixture must be stirred continuously. Subsequently, 37 per cent formalin was added dropwise in total while refluxing. The amount of aqueous NaOH solution is limited since the formed resin may become insoluble in common organic solvents. The water was removed from MEKFR, successively by evaporating with rotary evaporator.Practical implicationsThis study provides the application of ketonic resins. The modified ketonic resins containing lignosulphonate groups may also promote the adhesive strength of a coating. The cell walls of various cell types of plants, for example, wood fibres, vessels, and tracheid, have lignin as an important constituent. It constitutes 20‐30 per cent of the weight of wood.Originality/valueLignosulphonate modified ketonic resins have been synthesized in the presence of a base catalyst. These resins have higher Tg or Tm values and molecular weight than CFR and AFR alone and also have thermoset property. Environmental and ecological concerns have increased the attention paid by the chemical industry to renewable raw materials.