Studies On The Preparation And Synthesis Mechanism Of Formic Acid Lignin-based Adhesive

Various newly pulping techniques are emerging in today's quick development of Pulp & Paper making industry. In the past hundreds of years, the traditional alkali pulping has led an important role, but which has its own unconquerable weakness. So organic solvent pulping emerges as the times require, and formic acid pulping is one of the organic solvents pulping which is now popular. Formic acid pulping has made great progress after more than ten years researching, which has a high adaptability to raw materials compared with alkali pulping. Formic acid can be reused after the black liquor purified, which saves water and energy as well as the cost of the recycle black liquor. The structure of formic acid lignin is close to the raw material's, and it contains more active functions than alkali lignin (AL). Being a new pulping technique, formic acid pulping has a bright future because of its circulative, low pollution, low energy dissipation and water dissipation.This thesis contains the following contents: the structure of formic acid pulping black liquor lignin (FL) as well as the alkali pulping black liquor lignin is studied. PO is selected as a reagent to make the modified FL (MFL) in order to enhance the hydroxyl and activity of the lignin in this study. PU made by TDI and PEG, which is partly replaced with FL and MFL is studied. Using FL liquefied in Phenol (PFL) to synthesize PF can reduce the cost of PF while highlight the value of lignin. The composite system can change the capability of the resin adhesives. The resin adhesives are analyzed by using gel permeation chromatography (GPC). Fourier transform infrared (FTIR) and Differential Scanning calorimeters (DSC) to clarify the mechanism of lignin-based adhesive. The following results are obtained.(1) The content of phydroxyphenylpropane unit and syringylpane unit are larger in formic acid pulping black liquor than that in alkali pulping. So FL is more available than AL in the synthesis.(2) It was found that the concentration of hydroxyl group in the modified lignin was increased...