Study On Preparation And Curing Properties Of Phenolic Resins For Interior Wood Panel Adhesives

Resol phenolic resins are prepared by condensation under alkaline catalyst. With excellent bonding strength, good chemical stability and water resistance, Phenolic formaldehyde (PF) resins are used as wood panels for furniture and interior decoration. But PF resins contain high free phenol and formaldehyde content, which is serious pollution to environment and threat to human health. In addition, PF resins are hard,brittle and easy to crack, as well as high curing temperature and long curing time. Therefore, it has great practical significance to prepare environmental friendly PF adhesives with good performance.In this study, PF resins were prepared with phenol and formaldehyde as raw material, barium hydroxide alkaline as catalyst and urea as modifier. Effects of synthesis parameters and urea content on free phenol and free fprmaldehyde were studied. Granular activated carbon was modified by sodium hydroxide and nitric acid and the pore structure and the acidic functional groups on the surface of modified GAC were determined by BET nitrogen adsorption method and Bothem titration method, respectively. Effect of modified GAC content, adsorption time and adsorption temperature on adsorption capability for free formaldehyde were studied. And then melamine were added to improve the curing performance, curing kinetics and curing process were analyzed by DSC, and the effects of melamine on the phenolic resin adhesive properties and thermal stability properties were studied. The results were as below:(1) Good process was obtained by studying the synthesis parameters and urea content, free phenol and formaldehyde concentrations were reduced to less than 0.3%.(2) Pore structure and surface functional groups of GAC modified by NaOH were only changed a little, while the surface area and surface functional groups of GAC modified by HNO3 were all significantly increased. Moreover, the adsorption of GAC modified by HNO3 on free formaldehyde in PF resins had better adsorption capacity than that of GAC modified by NaOH.(3) PF resins were modified with melamine to improve curing performance. The curing kinetics of the system was analyzed by differential scanning calorimetry and the apparent activation energy was calculated by Kissinger and Ozawa equation. It turned out that melamine lowered curing temperature and reduce curing time.