A kind of preparation method of polycarboxylate water reducer

Abstract

The invention discloses a preparation method of a polycarboxylate water reducer. The main steps are: preparing the prepared raw materials into material A, material B and material C respectively; Inject nitrogen to replace the air in the reaction vessel; then material B and material C are simultaneously started and continuously added to the reaction vessel through metering equipment, the addition time of material B is 2 to 4 hours, and the addition time of material C is shorter than that of material B. It takes 15 to 45 minutes. After adding all the materials C, continue to stir and react for 30 to 90 minutes. Finally, add an alkali solution to adjust the pH value to 5 to 7; adjust the speed of adding materials B and C to the reaction vessel to keep the temperature in the reaction vessel Between 5 and 40°C; the present invention provides a preparation method of a polycarboxylate water reducer that does not require an external heat source by optimizing the redox initiation system, introducing high-activity small monomers, and adjusting the feeding process of raw materials. The performance of the polycarboxylate superplasticizer has been greatly improved.

Description

technical field [0001] The invention belongs to the field of water reducer preparation, in particular to a preparation method of polycarboxylate water reducer. Background technique [0002] In recent years, after years of development, the production of polycarboxylate superplasticizers in my country has gradually taken the lead in the world from imitation at the beginning. In 2011, my country's polycarboxylate superplasticizers had reached 35% of the market share. With the further improvement of people's requirements for the environment and environmental protection, polycarboxylate superplasticizer will replace other traditional admixtures. But at the same time, my country still lags behind the international leading level in the research and development of polycarboxylate superplasticizers, and more energy needs to be invested. [0003] The main component of polycarboxylate superplasticizer is polycarboxylate. The polymer structure of polycarboxylate determines the performa...

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Problems solved by technology

[0008] The current conventional production process is to add the raw materials into the reaction vessel at one time. Since the raw materials include alkenyl polyether macromonomers with relatively large molecular weights, and alkenyl polyether monomers such as acrylic acid and methacrylic acid with relatively small molecular weights, For small monomers, the reactivity ratio of alkenyl polyether macromonomers is lower than that of other alkenyl small monomers, that is, the conversion ratios of macromonomers and small monomers are different, and the actual composition of the copolymer is different from that of monomers. In addition, the distribution of macromonomers and small monomers in the linear polymer formed by copolymerization is uneven, and the content of small monomers with high polymerization activity in the product is high, and the content of macromonomers with low polymerization activity is high. Low, the latter is the opposite, which leads to a greater difference between the polymer structure of polycarboxylate and the ideal structure of alternating polymerization according to the proportion of monomers

[0009] CN104262547A discloses a method for synthesizing polycarboxylate water reducer with prenol polyether at low temperature. In this application, heating is used to dissolve prenol polyether, and the temperature of the system is adjusted to 10°C to 45°C. 4 to 12 hours to complete, heating can speed up the dissolution of prenol polyether, but it requires additional heating

[0010] CN103965413A discloses a low-temperature synthesis method of polycarboxylate high-performance water reducer, dissolving unsaturated polyoxyethylene ether in deionized water, stirring evenly, and then unsaturated monocarboxylic acid or partially unsaturated sulfonate monomer The solution is added, then the reducing agent and the chain transfer agent are added in sequence, and finally the oxidant aqueous solution is added dropwise to react; the polyoxyethylene ether is an alkenyl polyether macromonomer; the low-temperature synthesis method is to combine an alkenyl polyether macromonomer with Small monomers such as unsaturated monocarboxylic acid or partially unsaturated sulfonate are added to the reaction vessel at one time. The reaction in this low-temperature synthesis method is the copolymerization of alkenyl polyether macromonomers and alkenyl small monomers. The copolymerization activity of polyether-based macromonomers and small alkenyl monomers is quite different. This process of investing all small alkenyl monomers at one time will inevitably lead to homopolymerization of small monomers with high activity first, and then with Copolymerization of polyoxyethylene ether macromonomers cannot form a uniform long side chain distribution structure of alternating copolymerization, resulting in poor product performance, and it is difficult to ensure a high conversion rate of polyoxyethylene ether macromonomers with poor activity

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