Preparation method of polycarboxylate superplasticizer with high water reducing rate

Abstract

The invention discloses a preparation method of a polycarboxylate superplasticizer with a high water reducing rate. The polycarboxylate superplasticizer is prepared through adopting the preparation method comprising the following steps: according to parts by mass, with an unsaturated polyether macromonomer and an unsaturated sulfonic acid micromonomer as dropwise adding components 1, an azo initiator, a peroxide initiator and an initiation accelerant as dropwise adding component 2, acrylic acid as a dropwise adding component 3 and a molecular weight modifier as a dropwise adding component 4, feeding the unsaturated polyether macromonomer and the unsaturated sulfonic acid micromonomer as well as deionized water into a reactor, stirring and increasing the temperature; when the temperature rises to a dropwise adding temperature, orderly dropwise adding the dropwise adding components 1-4 to the reactor at a constant speed for 3-5 hours; after the dropwise adding is finished, preserving heat for 0.5 hour to 1.5 hours to obtain a copolymerization product; and after the reaction is finished, adding an aqueous solution of sodium hydroxide for neutralization to obtain the polycarboxylate superplasticizer having the pH value in the range from 6 to 7. The preparation method disclosed by the invention is simple in reaction process, easy to control the reaction and low in production cost; the product obtained through the reaction is high in water-reducing rate and good in slump loss resistant and slow-release properties.

Description

technical field [0001] The invention belongs to the technical field of chemical building materials, in particular to a preparation method of a high water-reducing polycarboxylate water-reducer. Background technique [0002] Since the 1930s, concrete admixtures have developed rapidly. At present, there are many types of concrete superplasticizers on the market with different functions. Different types of superplasticizers can achieve different effects. Water reducers are usually divided into ordinary water reducers (first generation), high-efficiency water reducers (second generation) and high-performance water reducers (third generation). [0003] The first generation of water reducers are mainly lignin sulfonates, which have a wide range of sources and simple and mature synthesis processes; however, this type of water reducer has a small water reducing rate, a large amount of air entrainment, low strength, and serious retardation , The scope of application is small. [0...

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Problems solved by technology

[0003] The first generation of water reducers are mainly lignin sulfonates, which have a wide range of sources and simple and mature synthesis processes; however, this type of water reducer has a small water reducing rate, a large amount of air entrainment, low strength, and serious retardation , the scope of application is small

[0004] The second type of water reducer is mainly naphthalene, aliphatic, and amino water reducers. This type of water reducer has a general water addition rate and a mature synthesis process; however, there are many toxic substances in the synthesis process, the amount of air-entraining is small, and it has color, etc. shortcoming

Among them, azobisisobutyronitrile and azobisisoheptanonitrile are easy to decompose, and are prone to danger during transportation, storage and use, and the conversion rate of the product is low

[0007] In the Chinese invention patent application CN102875047A "A Polycarboxylate High-efficiency Water-Reducer and Its Preparation Method", the synthesis method of the polycarboxylate water-reducer is complicated, the requirements for process equipment are high, and the synthesis time is relatively long. Invisibly increase the cost of production