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Method for preparing polycarboxylic acid grafted copolymer superplasticizer

A technology of graft copolymer and high-efficiency water-reducing agent, which is applied in the field of concrete admixtures, can solve the problems of limited reduction, lowering of apparent activation energy, and the inability to achieve optimal performance of polycarboxylate water-reducing agent.

Inactive Publication Date: 2014-08-06
CHINA UNIV OF MINING & TECH (BEIJING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

A redox system with high initiating activity has been used, generally an initiating system composed of a single initiator-single reducing agent, which can reduce the apparent activation energy, but the reduction is limited. The performance of the polycarboxylate superplasticizer prepared at low temperature not optimal

Method used

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  • Method for preparing polycarboxylic acid grafted copolymer superplasticizer
  • Method for preparing polycarboxylic acid grafted copolymer superplasticizer
  • Method for preparing polycarboxylic acid grafted copolymer superplasticizer

Examples

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preparation example Construction

[0112] Specifically, the preparation method includes the following synthesis steps:

[0113] Under low temperature conditions (5-30°C), add initiator I, substance a, substance b, chain transfer agent and reducing agent R aqueous solution into the reaction kettle, stir and react for 1-2h, then neutralize with alkaline solution to pH=6-8, white or light yellow liquid is obtained. Wherein, the alkaline substance used in the alkaline solution is preferably one or more of sodium hydroxide, potassium hydroxide, ethylenediamine and triethanolamine.

[0114] The adding mode of described initiator I, substance a, substance b, chain transfer agent and reducing agent R is as follows:

[0115] Method 1: In the polymerization reaction, the initiator I, substance a, substance b, chain transfer agent and reducing agent R are dissolved in water and then added at one time.

[0116] Method 2: In the polymerization reaction, dissolve substance a, substance b, chain transfer agent, reducing age...

Embodiment 1

[0123] Add 23.75 g of methallyl polyoxyethylene ether (m=12), 0.87 g of ammonium persulfate and 143.8 g of water into a 500 mL four-necked round bottom flask equipped with a thermometer, a stirrer and a spherical condenser. Adjust the temperature of the water bath to 30°C, stir until the methallyl polyoxyethylene ether and ammonium persulfate are dissolved, and use a peristaltic pump to separately mix a solution consisting of 9.12g of acrylic acid and 15.5g of water, 0.081g of sodium bisulfite, 0.001 A solution consisting of 1 g of ferrous sulfate, 0.273 g of 3-mercaptopropionic acid and 15.8 g of water was added dropwise to the four-necked flask within 3 hours. After the dropwise addition, the reaction was stirred for 1.5h. Add 30% sodium hydroxide solution to neutralize to a pH value of 7, and replenish water to obtain a light white liquid with a concentration of 40%. That is to prepare polycarboxylic acid graft copolymer high-efficiency water reducer PC1 at low temperature...

Embodiment 2

[0125] Add 90g of methallyl polyoxyethylene ether (m=51), 159g of methoxypolyethylene glycol acrylate (n =35), 6.8% hydrogen peroxide 12.54g and 138.2g water. Adjust the temperature of the water bath to 5°C, stir until methallyl polyoxyethylene ether and methoxypolyethylene glycol acrylate are dissolved, and use a peristaltic pump to separately mix the solution consisting of 44.91g of acrylic acid and 25g of water and 0.159g of ascorbic acid , 1.17g of sodium thiosulfate, 1.56g of mercaptoacetic acid and 38.2g of water were added dropwise to the four-necked flask within 3 hours. After the dropwise addition, the reaction was stirred for 1.5h. Add 30% potassium hydroxide solution to neutralize until the pH value is 7, and replenish water to obtain a light yellow liquid with a concentration of 40%. That is to prepare the polycarboxylic acid graft copolymer high-efficiency water reducer PC2 at low temperature for the composite initiation system of the present invention.

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Abstract

The invention discloses a method for preparing a polycarboxylic acid grafted copolymer superplasticizer. In the method, the preparation is implemented at the low temperature of 5-30 DEG C; a used initiating system is a complex initiating system which adopts the combination of one initiator I and various reducers R, or one reducer R and various initiators I or various initiators I and various reducers R, wherein the initiator (s) I is (are) selected from hydrogen peroxide, persulfate salt LS2O8 and a water-soluble azo initiator W, and the reducer (s) R is (are) selected from ascorbic acid and certain kinds of inorganic salt. The preparation method is simple, excellent in repetition stability and low in cost, does not require heating, and avoids toxicity and pollution; the prepared superplasticizer is high in water-reducing rate, and excellent in adaptability and slump-retaining capability, thereby being suitable for popularization and application.

Description

technical field [0001] The invention relates to the technical field of concrete admixtures, in particular to a method for preparing polycarboxylic acid graft copolymer high-efficiency water reducers. Background technique [0002] As the main building material, concrete plays an important role in the construction and development of national infrastructure. Concrete is usually composed of stones, sand, cement and water. With the development of society and the advancement of science and technology, ready-mixed concrete, that is, ready-mixed concrete, has developed rapidly. As a concrete chemical admixture, polycarboxylate superplasticizer can effectively reduce the water consumption per cubic meter of concrete, increase the fluidity of ready-mixed concrete, and improve the workability of concrete, making it an essential component of concrete. [0003] The polycarboxylate superplasticizer has a comb-shaped structure, and is synthesized at a synthesis temperature of 50-90°C with...

Claims

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Application Information

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IPC IPC(8): C08F290/06C08F220/06C08F228/02C08F220/28C08F218/08C08F212/14C08F230/02C08F220/58C08F4/40C08F4/04C04B24/26C04B24/16C04B103/30
Inventor 王栋民张力冉王浩王启宝逄建军李娟张述雄赵计辉
Owner CHINA UNIV OF MINING & TECH (BEIJING)
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