Method for preparing polyacrylic acid or sodium polyacrylate

Abstract

The invention discloses a method for preparing polyacrylic acid or sodium polyacrylate. The method comprises the following steps: 5 to 35 mass percent of crylic acid, 0 to 14 mass percent of sodium hydroxide, 0.5 to 6 mass percent of persulfate, 0.2 to 3 mass percent of sodium bisulfite , 0.05 to 3 mass percent of L-ascorbic acid, 0.5 to 10 mass percent of sodium hypophosphite and 50 to 90 mass percent of water are mixed to have polymerization reaction for over one hour at a temperature of between 25 and 60 DEG C to obtain the polyacrylic acid or the sodium polyacrylate; the viscosity-averagemolecular weight of the polyacrylic acid or the sodium polyacrylate is between 800 and 50,000; and the conversion rate of the polyacrylic acid or the sodium polyacrylate can reach over 96 percent. The method has the advantages that the polyacrylic acid or the sodium polyacrylate with low molecular weight is synthesized once, has low starting reaction temperature, less energy consumption, rapid reaction speed, high utilization efficiency of equipment, a simple process and convenient operation.

Description

technical field [0001] The invention relates to a method for preparing an organic polymer, in particular to a method for preparing an organic polymer using a carbon-carbon unsaturated bond as a raw material. Background technique [0002] At present, a large number of domestic patent documents (such as document numbers CN1106355C, CN1141262C, CN101172718A, CN1754840A, etc.) have reported the method of using low molecular weight polyacrylic acid or copolymers as one of the components to compound the production of scale inhibitors, scale removers or corrosion inhibitors, But do not relate to the preparation method of low molecular weight polyacrylic acid (sodium) in these patent documents. [0003] There are also domestic patent documents (such as CN1654369A, CN101103048A, CN1085568A, CN1986581A, etc.) to report the preparation method of low molecular weight polyacrylic acid (sodium), but these methods all require polymerization at a higher starting temperature, and when carryi...

AI Technical Summary

Problems solved by technology

It can be seen that the existing methods and processes not only have complex and cumbersome procedures, but also have high energy consumption and low equipment efficiency.

[0004] Existing methods for preparing low-molecular-weight polyacrylic acid (sodium) also include the following: (1) adopting sulfur-based compounds to prepare as a molecular weight regulator, this method is basically no longer used at present because the product has a bad smell; 2) Virahol is adopted as molecular weight regulator (such as U.S. Patent US4301266, 1981, BASF A.-G. Muenster, A.andRohmann, M), this method needs high temperature (greater than 120 ℃) ​​high pressure in the reaction process, reaction conditions Harsh, and need to distill out excess isopropanol in the post process, this process energy consumption is loaded down with trivial details; (3) adopt metal salt (such as Cu 2+ ) as an initiating system (such as U.S. Patent US4314044, 1982, Rohm and Haas Co, Hughes, K.A, Kine, B.B. and Swift, G.), the reaction conditions of this process also need to meet higher temperature (greater than 90 ° C), and need It is completed in the case of continuous feeding, and the energy consumption is cumbersome, while Cu 2+ It is easy to cause environmental pollution again; (4) adopt water-soluble azo compound to make initiator (such as Japanese Patent JP6438403,1989, Kao Corporation, Kondo Akihiro, Igarashi Zheng, Tsudori Riki), this method needs to prepare specific Azo compounds, the process is complicated; (5) Sodium hypophosphite is used as a molecular weight regulator, and the monomer is acrylic acid (sodium), and the copolymerization method is not adopted