Research On Key Technology Of AKD

AKD,short for Alkyl Ketene Dimmer,is a waxy white solid with melting temperature of 40-50 deg C,soluble in organic solvents including ethanol,benzene,and chloroform,capable of resisting penetrating agent including weak acid and weak base.AKD is mainly used as a sizing agent in paper pulp industry,for curbing the paper's tendency to absorb liquids,in using of food packaging and other related uses.At present,the production of Alkyl Ketene Dimmer is mainly in countries including United States,Japan,France,Germany,Sweden,Britain,Holland,Switzerland and China.The United States,which has a long history of Alkyl Ketene Dimmer production,is the first country to produce it,and also the main producing country in the world.The research and development of Alkyl Ketene Dimmer starts relatively late in China,and with a general small scale,the competitiveness of production companies is weak.The production process of AKD is consisted by two parts: stearic acid acyl chloride reaction and condensation reaction of stearic acid acyl chloride.In traditional process,the condensation of stearic acid acyl chloride can be divided into two types,with-solvent and without-solvent,depending on whether the toluene solvent is added into the process.As the solvent is hard to be separated from the product,and the solvent(toluene)is toxic,with-solvent process cannot be used for food packaging and other high-grade paper production,thus the application of products is greatly limited.On the contrary,products from without-solvent process have high purity,containing no toxic substances,resulting in good quality and a wide range of applications,making this process a direction of technology development.In this work,the technical condition of acyl chloride reaction and the rheological characteristics of mixture at condensation stage during AKD synthesis were studied.Based on the results,further supplementary study and verification experiments were performed,accumulating data and operating experience for next step's industrial production,providing technical support and theoretical basis for the composing of process technical documents of industrial production installations.