Synthesis Of Pitch Resin From Mid-low-temperature Coal Tar Pitch

Carbon material is an important functional and structural material, so there arebroad application prospects in aviation, aerospace, biomedical material, chemicalindustry and other fields. In the preparation of carbon materials, people use theappropriate binder to realize the process of kneading, molding, baking graphitization,etc. The carbon materials are produced for meeting different needs. The pitch resin isequipped with high carbon yield and good affinity to the carbon materials. Becausethe mid-low-temperature coal tar have high yields and processing capacity solid, thereis a large number of inexpensive mid-low-temperature coal tar pitch. It is verymeaningful about deep processing mid-low-temperature coal tar pitch.A pitch resin has been synthesized by using mid-low-temperature coal tar pitchas raw materials and paraformaldehyde as cross-linking agent at the presence ofp-toluenesulfonic acid. In the experiments, the effects of various technologic factorssuch as addition of cross-linker and catalyst, reaction temperature and reaction timeon the properties of the pitch resin is studied in detail. On the basis of single-factortest, it carried out the orthogonal optimizing experiment in order to find optimalsynthetic conditions. And the thermal conversion experiment of the pitch resin wascarried out. The raw materials and their products are characterized by infraredspectrometer, thermo gravimetric analyzer, light microscope, scanning electronmicroscope and x-ray diffractometer. These studies provided some valuableinformation for the preparations and applications of the pitch resin.The experimental results indicated that the softening point, coking value andβ-resin of the pitch resin had been obviously improved by increasing the reactiontemperature and the addition of catalyst in the synthesis process. The orthogonalexperiments showed that the softening point of the pitch resin was between112.8℃and153.4℃, the coking value was between27.42%and37.63%, β-resin was between25.27%and43.03%. The bond strength of the mid-low-temperature coal tar pitch andpitch resin had been obviously improved by the quality ratio of raw material andmagnesia. The determination of bond strength had the maximum value when thequality ratio of raw material and magnesia for2.5:15. The bond strength of themid-low-temperature coal tar pitch had been obviously improved by increasing thereaction temperature, could increase by as much as16. The bond strength of pitchresin had been decreased with increasing the reaction temperature, it was decreasingby as much as7. The bond strength of pitch resin was higher than the bond strength ofthe mid-low-temperature coal tar pitch. Through TG and DTG analysis, it found that pyrolysis condensation process of pitch resin were different from mid-low-temperature coal tar pitch, and the temperature of starting weight loss and thetemperature responded to the peak rate of the weight loss wave increase by40℃, themost mass loss rate was decreasing by as much as0.05mg/min, and the total mass lossrate relatively decreased by as much as9%. Through FT-IR and NMR analysisshowed that the intensity of absorption peak of aromatic content were hardly changed,the mid-low-temperature coal tar pitch and paraformaldehyde occurred substitutionreaction, Hβand Hγof the aromatic ring side chains increased, and there were alcoholsand unsaturated hydrocarbons in the products. The photograph of mid-low-temperature coal tar pitch coke had light extinction clutter, uneven surface and nonegrain orientation. The photograph of pitch resin coke had complete extinction andsmooth surface. Through XRD analysis showed that pitch resin coke was easiergraphitization than mid-low-temperature coal tar pitch coke, and synthesis conditionof pitch resin affected graphitization and entropy of coke.