Study On Preparation And Bonding Strength Of Environmental PF Resins Adhesives

Resole resins are prepared by polycondensation reaction under alkaline condition using phenolics and aldehydes as raw material. Resol resins can be used as wood adhesives due to their good water resistence, fairly electric insulated and low price. However, there are some issues of PF resins adhesives, such as high free phenol and free formaldehyde, high curing temperature and long curing time, as well as low bonding strength caused by tight arrangement of benzene ring. In order to solve these problem, PF resins adhesives were prepared by phenol and formaldehyde using Ba(OH)2as catalyst, and urea was added as modifier. The effect of synthesis parameters and urea addition on free phenol and free fprmaldehyde were studied. Then curing process of PF resins adhesives was studied by Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR). And curing agents were added to improve the curing performance of PF resins adhesives. The effect of synthesis parameters and modifier on bonding strength was also studied, and Fourier Transform Infrared Spectroscopy (FTIR) and Thermal Gravimetric Analysis (TGA) were used to analyse heat performance of PF resins adhesive. The results were as follows:(1) Good process was obtained by altering synthesis parameters and urea dosage. Both free phenol and free formaldehyde were redused under0.3%.(2) MgO and Na2CO3were added separately to improved curing performance of PF resins. It turned out that Na2CO3was the better agent which can lower curing temperature and reduse curing time.(3) Organic silicon and H3BO3were added to improve glueability of PF resins adhesives. The bonding strengths of organic silicon-modified PF resins and H3BO3-modified PF resins were increased from1.5MPa to6.1MPa and8.2MPa.