聚羧酸减水剂的常温合成工艺

Synthesis process of polycarboxylic water reducer at ambient temperature

目前聚羧酸减水剂的合成工艺主要以加热为主,低温合成工艺报道较少。本文为了解决这一问题,以异戊烯醇聚氧乙烯醚(TPEG)、丙烯酸(AA)为主要聚合单体,研究分析反应温度、保温时间、A/B液滴加时间、酸醚比、引发剂过硫酸铵用量(APS)等因素对合成减水剂产品性能的影响。并利用正交试验,筛选出常温条件下较优的合成工艺:酸醚比n(AA)∶n(TPEG)=3.5∶1,引发剂过硫酸铵用量(按TPEG单体质量分数计)为0.5%,反应温度30℃,A液滴加2.25h,B液滴加3.5h,保温时间1.5h。合成减水剂产品在水灰比0.29,掺量0.25%的条件下,水泥净浆初始流动度达到240mm,1h后净浆流动度损失5mm,相同掺量下与其他减水剂产品相比具有更好的分散性和分散保持性。

The synthesis process of polycarboxylic water reducer was mainly composed of heating. The synthesis process at ambient temperature has been less reported. To solve this problem,the paper researched the influences of reaction temperature,holding time,feeding time of A and B,acid ether ratio,and ammonium persulfate（APS）weight on the performance of polycarboxylic water reducer that was synthesized by using methyl allyl polyethenoxy ether（TPEG）and acrylic acid（AA）as the main polymeric monomers. Orthogonal experiments showed that when the temperature is 30℃,holding time is 1.5 hours,feeding time of A is 2.25 hours,feeding time of B is 3.5 hours,n（AA）∶n（TPEG）=3.5∶1,and APS ratio is 0.5%,the polycarboxylic water reducer achieves optimum performance. When water-binder ratio is 0.29 and a dosage of 0.25% of such obtained water reducer is used,the initial cement paste fluidity reaches 240 mm and the slump loss is 5mm after 1 hour. It has better dispersity and dispersion stability than other polycarboxylic water reducers at the same dosage.