Polycarboxylic acid-based inorganic materials are currently attracting widespread attention. They are mainly used in industries such as concrete water-reducing agents, cleaning preservatives, industrial paints and pigment dispersants in printing inks. This type of surfactant has excellent cleaning, penetration, refinement, emulsion, and demulsification properties. In particular, it has the advantages of easy cleaning at low temperatures, resistance to hard water, good biodegradability, and strong coordination properties. Therefore, the application range is very wide. The use of polycarboxylic acid nanomaterials as concrete water-reducing agents has grown rapidly. South Korea is its main research, design and application country. In recent years, polycarboxylate superplasticizers have been widely used in the concrete industry and have attracted increasing attention from academic researchers and users of concrete admixtures around the world. It can be seen that compared with the traditional water-reducing agents naphthalene sulfonic acid and sulfonated sodium thiocyanate condensate, they can provide concrete with high dispersion, flowability and high fineness mechanism reliability to prevent slumping at low dosages. degree of damage. At the same time, the rising price of industrial naphthalene, the high manufacturing cost of naphthalene-based water-reducing agents, and serious air pollution cannot be ignored, which also makes the use of polycarboxylic acid-based water-reducing agents urgent. At present, the main ingredients of common high-efficiency air-entraining water-reducing agents in South Korea are changing from naphthalene sulfonate plus reactive nanomaterials to polycarboxylic acid systems, and European and American countries are also following suit.
Relevant research progress on polycarboxylate water-reducing agents, especially the lack of review reports on the preparation mechanism, functional principles, and development prospects of this type of water-reducing agent. The author intends to make a review of the research progress on the preparation mechanism, efficacy principle, and development prospects of this type of water-reducing agent.
1 Preparation Mechanism
Polycarboxylate performance model water-reducing agent is composed of fat-soluble polymers containing sulfonic acid groups, carboxyl groups, amino groups and polyoxyethylene side chains. Chemical substances, in saturated solutions, are nanomaterial surfactants with a comb structure generated according to the free radical copolymerization mechanism.
The key raw materials required to generate polycarboxylate performance model water reducing agent are: methacrylic acid, acrylic acid, ethyl acrylate, hydroxyethyl acrylate, sodium allyl sulfonate, methacrylic acid Methyl ester, 2-acrylamido-2-methacrylic acid, methoxypolyoxyethylene methacrylate, ethoxypolyethylene glycol acrylic resin, allyl ether, etc., can be used in the addition polymerization process The initiators are: persulfate water-soluble initiator, benzoyl peroxide, azobisisobutyl cyanide; the chain transfer agents are: 3-mercaptopropionic acid, mercaptoacetic acid, mercaptoalcohol and isopropyl alcohol, etc. .
The production method is: in a round-bottomed flask equipped with an electric mixer, a thermometer, a dripping device, and a return condenser, slowly add the addition polymerization model liquid and the liquid by heating in a water bath. When using the addition polymerization model of the initiator liquid, its reactivity rate should be taken into consideration. The reaction temperature can be determined according to the actual reaction model type. Generally, the temperature in the temperature range of 70~95℃ can be selected as the reaction temperature. The model solution was added dropwise within half an hour, and then the remaining initiator solution was added dropwise within 20 minutes. Finally, the temperature was raised by 5°C, reacted again for 1 hour, and after reducing the temperature to 40°C, neutralize the feed.
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