Preparation And Application Of Phenolic Resol Resin Modified By Wheat Straw Cmp Pulping Spent Liquor

This study evaluated the potential for partially replacing phenolwith wheat straw CMP pulping spent liquor in synthesis of phenolicresol resin and examined the strengthening effect of prepared resins onrecycled corrugating medium which was measured by using the synthe-tic products in the surface sizing of recycled corrugating medium.The wheat straw CMP pulping spent liquor at solids contents up to28.2%was modified by pheonlation prior to the manufacture of phenol-lic resol resin. An orthogonal test was applied to determine the influen-ce of manufacturing variables on the T peeling strength of phenolicresol resin which was syhthesized with phenolation products. Theoptimum condition for phenolation of wheat straw CMP pulping spentliquor appeared to be at105℃and for150min and the mole ratio ofsodium hydroxide to phenol was0.4:1. The characterization of phenola-tion products was accomplished by Fourier transform infrared (FT-IR).Pulping spent liquor-phenolic resol resin was prepared using thephenolation products as the substitution of phenol at varying ratios from15.0%to35.0%. Specifically, the effects of reaction conditions on theproperties of pulping spent liquor-phenolic resol resin were optimaizedby single factor experiment. The optimum reaction conditions forpreparing of pulping spent liquor-phenolic resol resin can be concludedas follows: the addition of pulping spent liquor was20.0%of phenol,the formaldehyde to phenol mole ratio was2.0:1, the mole ratio ofsodium hydroxide to phenol was0.4:1, the additon reaction temperaturewas65℃and reaction time was1.5h, the condensation reaction temper-ature was83℃and reaction time was2.5h. According to the optimumreaction conditions for preparing of pulping spent liquor-phenolic resolresin, pulping spent liquor-urea-phenolic resol resin was synthesized using urea to replace the other part of phenol at varying ratios from10.0%to35.0%. Pulping spent liquor-urea-glyoxal-phenolic resol resinwas prepared using glyoxal to substitute partial amount of formalde-hyde at replacement levels of3.0%~28.0%, and the other reactionparameters were similar to the synthesis of pulping spent liquor-urea-phenolic resol resin. The experimental results suggested that thepercentage of substitution of phenol with urea was25.0%, and substi-tuteon of formaldehyde by glyoxal was13.0%. According to the optim-um conditions for preparing of three kinds of modified phenolic resolresins, specimens for pulping spent liquor-phenolic resol resin, pulpingspent liquor-urea-phenolic resol resin and pulping spent liquor-urea-glyoxal-phenolic resol resin were prepared respectively. The pH value,viscosity, solid content, free phenol content, free formaldehyde contentand T peeling strength of these modified phenolic resol resins weredetermined and compared with the phenolic resol resin using purephenol in the synthesis. The results obtained from above showed thatthe physical properties of these modified phenolic resol resins weresimilar or even better than phenolic resol resin and the performace ofpulping spent liquor-urea-phenolic resol resin demomstrate the bestperformance among those resins.Those modified phenolic resol resins were characterized by usingFT-IR spectroscopy and thermogravimetric analysis (TGA). FT-IR spec-troscopy revealed that those modified phenolic resol resins had similarfunctional guoups with phenolic resol resin. Thermal stability of thosemodified phenolic resol resins were found to be inferior to phenolicresol resin, leading to a lowered decomposition temperature and a redu-ced amount of non-volatile content residue at elevated temperature.For the sake of evaluating strengthening effect of those modifiedphenolic resol resins, the synthetic products were used in the surfacesizing of recycled corrugating medium, and the strengthening propertiesof modified resol resins were measured by detecting the strengthproperties of recycled corrugating medium. Compared with recycledcorrugating medium without surface sizing, the strengrh properties (tensile strength and ring crush strength) were improved throughapplying surface sizing with modified phenolic resol resins. Theoptimum process conditions for application of prepared resol resins onstrengthening recycled corrugating medium were concluded as follows:the dosage of prepared resol resins was4.0%(based on dry weight ofhandsheet), cured temperature was140℃and cured time was25min.The strengthening effect of pulping spent liquor-urea-phenolic resolresin was the best among those prepared resol resins. It was suggestedthat a new way to realize the integrated utilization of pulping spentliquor could be achieved.