The Research On "phenol-melamine-formaldehyde" Co-condensed Resins

Urea-formaldehyde(UF), Phenol-formaldehyde(PF) and Melamine-formaldehyde(MF) resins are the main adhesives in wood industry. PF is becoming the leading exterior-graded adhesive because of its good weatherability, water resistance, temperature resistance and high adhesive strength. But Because the yield of petroleum has reduced as a result of energy sources crisis, the cost of its by-product -Phenol is higher and higher; Besides, long solidification time, high solidification temperature and its toxicity restrict the application of PF, consequently, nowadays, in order to replace proportion of phenol, study on the modification of PF with other material is one of the hotspots in the research field.In this study, we discussed the formula and technics of PMF from the point of co-condensation, and carried through optimized examinations, finally, developed a kind of high cost-performance exterior-grade co-condensed resins, which has tremendous market development potential, and can be used as dipped resins in the manufacture of bamboo curtain plywood.Today the research on PMF resins around the world has just begun and few summary science literatures on its mechanism has been published.The main study includes:(1) Study the basic formula of PF and MF, design and optimize the formula of PMF.(2) Design and optimize the technics of PMF.(3) Compare the performance of co-condensed resins PMF with that of conventional blended resins.(4) Study the transformation of its structure formation with fourier transform infrared spectroscope.For this kind of PMF resins, the study indicated that:(1) The best formula of PMF is: n(Fi)/n(P)=1.69; n(M)/n(P)=2.74; n(F2)/n(M)=2.25; n(NaOH)/n(P)=0.29.This kind of PMF resin has good performances, which keeps the good performances of PF resins. The content of toxicant in PMF resins, such as free phenol and free formaldehyde, is lower than that in PF resins. Moreover, the color of PMF is tint, which is similar to the nature color of wood or bamboo and remedy PF resins' shortcomings. At the same time, it overcomes some disadvantages of MF resins, such as bad flexility, bad water dissolution abilities and stabilities. Properties of bamboo curtain plywood bonded with PMF can measure up JG/T 156-2004.(2)The best technics of synthesizeing PMF is:the proportion of the first added formaldehyde is seventy-five percent; adding water when added the first part formaldehyde; the condensation temperature is 92℃.(3)The cost of materials is lower than that of PF, just 68.19% of the cost of PF.(4)Compare with the conventional blended resins, co-condensed PMF resins, the technics of PMF is simple, at the same time, properties of bamboo curtain plywood bonded with PMF is better than that of blended resins.