Multi-branched amphoteric polycarboxylic acid high-performance water-reducing agent synthesizing method

Abstract

The invention relates to a water-reducing agent used for fresh mortar and concrete, in particular to a multi-branched amphoteric polycarboxylic acid high-performance water-reducing agent which has high water-reducing efficiency and good slump loss resistant property, as well as a preparation method thereof. The method comprises the following steps: a single a or B and a single c react to generate an ester A; the single c and a single d react to generate an ester B; filling water, the single a or the single b, the single c, the ester A, and the ester B into four reaction bottles according to a certain ratio, and then adding a mixture solution E; and instantly, dripping a mixture C solution and a mixture solution D, and carrying out polymerization and neutralization reaction so as to obtain the water-reducing agent. The water-reducing agent provided by the invention introduces a cationic group, has a novel pellet-shaped multi-branched molecular structure, better dispersivity, and good slump loss resistant property, can be easily poured and compressed, can be extensively applied in various kinds of cement, greatly solves the problem that the polycarboxylic acid water-reducing agent is sensitive to the cement and can not be applied, has a suitable air content and greatly improved resistance to freezing and thawing, and greatly prolongs the service life of the concrete.

Description

technical field [0001] 本发明涉及一种用于新拌砂浆、混凝土等的减水剂,尤其涉及一种具有高减水率、优异保坍性能的多支化两性聚羧酸高性能减水剂及其制备方法。 Background technique [0002] 减水剂是配制混凝土时使用的一种外加剂,主要作用有以下几个方面:增加水化效率,减少单位用水量,增加强度,节省水泥用量;改善尚未凝固的混凝土的和易性,防止混凝土成分的离析;提高抗渗性,避免混凝土建筑结构漏水,增加耐久性,增加耐化学腐蚀性能;减少混凝土凝固的收缩率,防止混凝土构件产生裂纹;提高抗冻性,有利于冬季施工。 [0003] 第三代聚羧酸减水剂的减水率、坍落度损失、混凝土收缩比等指标都优于第二代萘系减水剂。聚羧酸系减水剂作为继萘系、蜜胺系、脂肪族系和氨基磺酸盐系减水剂之后研制生产成功的新型高性能减水剂,以其在掺量较低时就能产生理想的减水和增强效果、对混凝土凝结时间影响较小、坍落度保持性较好、与水泥和掺合料适应性相对较好、对混凝土干缩性影响较小、生产过程中不使用甲醛和不排出废液、碱含量低等突出特点,从一开始就受到研究者和部分应用者的推崇。由于我国水泥品种较多,聚羧酸系减水剂并不是适应所有水泥,再加上在工程中的应用经验相对还较缺乏,对其性能认识尚不够深刻,满足不了追求高减水率和高保坍性的要求,给聚羧酸系减水剂应用范围的扩大和全面快速推广带来了一定阻力。 [0004] 针对上述现象和一些工程应用中存在的问题,国内对解决混凝土坍落度损失方面取得了一定的效果,但并不是很理想。许多专家学者致力于这方面的研究。到目前为止,缓慢释放理论和特殊高分子阴离子表面活性剂作用机理能更高地应用解释坍落度损失的原理。尤其是缓慢释放理论,在反应性高分子中,以酯基、酰胺基等的形式存在的基团在混凝土的碱性成分的作用下发生水解反应,从不溶于水的高分子变为水溶性高分子分散剂进入溶液中,这种水溶性高分子聚合物被吸附在水泥粒子表面,使水泥粒子不断处于分散状态,从而维持了其分散性。由于水解反应仅在其表面,因此溶解过程是缓慢进行的,需要一定的时间,从而有效地防止坍落度损失。 [0005] 我们发现,由中心支点向外扩散聚合球团状多支化的高分子结构更适合于解释缓慢释放理论:水解反应在其表面,溶解过程是缓慢进行的,需要一定的时间,从而有效地防...

AI Technical Summary

Problems solved by technology

[0007] The cationic group is introduced into the multi-branched structure, so that the polycarboxylic acid macromolecules have both anions and cations, which solves the problem that the current hyperbranched structure polycarboxylate high-performance water reducer only adsorbs cations in cement hydrate, but not anions. It also solves the problem that the current amphoteric polycarboxylate high-performance water reducer does not have multi-branched polymerization

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