甲基萘磺酸甲醛缩合物减水剂的合成工艺

以工业甲基萘为原料,通过磺化、水解、缩合与中和反应合成了甲基萘磺酸甲醛缩合物(MNSF),考察了反应工艺参数对产物作为混凝土减水剂的分散性能的影响.结果表明,合成MNSF最优工艺为:n(甲基萘)n∶(浓硫酸)n∶(水解加水量)n∶(甲醛)∶n(缩合加水量)=11∶.25(∶1.25～1.5)0∶.924∶.6;磺化反应温度160～165℃,时间3～3.5 h;水解反应温度110～120℃,时间15～30 min;缩合反应的加醛量与温度是该段影响产品分散性能的主要因素,缩合反应温度110℃,时间4 h;水解前后酸度应控制在30%左右.MNSF在掺量为水泥质量的0.5%时,砂浆减水率达到16%,比萘磺酸甲醛缩合物钠盐(FDN)高4%,抗折和抗压强度与FDN相近.

Synthesis of Methylnaphthalene Sulfonic Formaldehyde Polycondensate

Methylnaphthalene sulfonic formaldehyde condensate(MNSF) was synthesized from industrial methylnaphthalene by four steps:firstly,sulfonated by H2SO4,then hydrolysised by H2O,nextly condensated by HCHO and neutralized by NaOH.The factors influencing the dispersion ability of MNSF used as superplasticizer were investigated.The optimum reaction conditions were described as below: the mole ratio of material is n(methylnaphthalene)∶n(H2SO4)∶n(H2O of hydrolysis)∶n(HCHO)∶n(H2O of condensation)=1∶1.25∶(1.25～1.5)∶0.92∶4.6;sulfonation temperature was 160～165 ℃,sulfonation time was 3～3.5 h;hydrolysis temperature was 110～120 ℃,hydrolysis time was 15～30 min;condensation temperature was 110 ℃,condensation time was 4 h;the acidity value before and after hydrolysis was controlled near 30%.When the dosage of MNSF was 0.5%,the water-reducing ratio reached 16%,and 4% more than that of FDN,the flexural and compression strength of the added MNSF cement mortar approached that of FDN.