Synthesis And Application Of The Modified Phenolic Resin Wood Adhesives

In recent years, outdoor plywood panels have been greatly used for meeting the consumption demand with the rapid development of China’s economy. Generally, outdoor plywood panels use phenolic resin as adhesive, indicating the broad application prospects of phenolic resin. Therefore, the synthesis of phenolic resin with excellent quality and high-performance ratio becomes a hot topic today.The objective of this thesis is to synthesize phenol-urea-formaldehyde resins with the quality of high-performance ratio, good water resistance and long storage by using phenol, urea and formaldehyde. Effects of the synthesis process parameters on structure, curing characteristics and physical properties were comprehensively discussed by optimizing the synthesis procedure and using modern analytical methods. When melamine, methanol, resorcinol, organic silicon or others were added as modifiers, the influence on physical property and chemical property was also studied.Several conclusions are obtained:the optimum condition was determined, the F/P molar ratio was3:1, the additive amount of urea was68.3%of phenol and it was added in the middle of the reaction, co-condensation reaction time was30min at the temperature of95℃. Bonding strength of resin improved significantly when melamine was added, furthermore, adding2%melamine made bonding strength increase by12%and storage period shorten22%. When the content of methanol in formaldehyde was less than or equal to9.96%, it almost had no effect on bonding strength while the storage period of the resin can be improved by40%. If resorcinol was added in the synthesis stage of the co-condensation reaction, resin bonding strength can be greatly improved, by an amount of0.58%, bonding strength can be increased by25%and the storage period of resin was also extended. Adding organic silicon in different stages of the synthesis, when3%o silicone was used in the co-condensation stage, the resin showed the best quality of bonding strength with an increase of26.67%. For veneer moisture content of15%to17%, resin glued plywood bonding strength can reach the national standard after aging and preloading.