木质素改性酚醛树脂结合镁碳砖的研究

Research on magnesia carbon bricks bonded by lignin modified phenol formaldehyde resin

为了降低酚醛树脂的生产成本并提高其低温结合强度,以木质素磺酸钙为原料部分替代苯酚,以氢氧化钠为催化剂,合成了木质素改性酚醛树脂(LPF),并将其作为结合剂用于镁碳砖的制备,通过研究不同木质素磺酸钙用量(其质量分数分别为10%、20%、30%、40%、50%)、不同催化剂用量(外加质量分数分别为1%、2%、3%、4%、5%)以及不同反应时间(分别为1、1.5、2、2.5、3 h)合成的LPF对镁碳砖200℃24 h烘后常温性能的影响,优化了LPF的合成工艺条件,同时对比了LPF结合和传统酚醛树脂结合镁碳砖于200℃24 h烘后和1 200℃3 h处理后的常温物理性能和高温抗折强度。结果表明,适于制备镁碳砖的LPF的最佳合成工艺条件为:木质素磺酸钙质量分数为30%,催化剂质量分数为1%,反应时间为2 h。用最佳工艺合成的LPF制备的镁碳砖,经200和1 200℃分别处理后的体积密度为2.84和2.82 g·cm-3,显气孔率为9.6%和14.6%,抗折强度为17.8和6.4 MPa,耐压强度为72.3和48.7 MPa;1 400℃下的高温抗折强度为7.3 MPa。与传统酚醛树脂结合镁碳砖相比,其性能均有所提高。

In order to reduce the cost and to improve the low temperature bonding strength of phenol formal- dehyde resin （PF）,the lignin modified phenol formaldehyde resin （LPF） was synthesized using calcium lignosulfonate as a partial replacement of phenol,and sodium hydroxide as catalyzer. Then the magnesia carbon bricks were prepared using the LPF as binder. Different process conditions of LPF such as calcium lignosulfonate additions （ 10% ,20% ,30% ,40% and 50%, in mass,the same hereinafter）, catalyzer addi- tions （extra added,1%,2%,3%,4% and 5%） and reaction times （1 h,1.5 h,2 h,2.5 h and 3 h） were in- vestigated. Effects of prepared LPF on properties of magnesia carbon brick （ baked at 200 ℃ for 24 h） were researched in order to modify the synthesizing conditions of LPF. Cold physical properties and hot modulus of rupture of magnesia carbon bricks bonded by LPF and by traditional PF after baked at 200 ℃ for 24 h and fired at ! 200 ℃ for 3 h were compared, respectively. The results show that the optimal synthe- sizing conditions of LPF for preparing magnesia carbon bricks are 30% calcium lignosulfonate, ：1% catalyzer,2 h reaction time. The magnesia carbon bricks bonded by the optimal LPF achieve. （：1）the bulk densities 2.84 g·cm^-3 and 2.82 g·cm^-3, apparent porosities 9.6% and 14.6%, moduli of rupture ：17.8 MPa and 6.4 MPa,crushing strengths ？2.3 MPa and 48. ？ MPa,after baked at 200 ℃ and fired at 1 200 ℃, respectively; （2）the hot modulus of rupture 7.3 MPa after fired at t 400 ℃. The above properties above are higher than those of the magnesia carbon brick bonded by PF.