A low-valence variable valence cation-modified polycarboxylate water-reducing agent masterbatch and a low-temperature preparation method thereof

Abstract

The invention discloses a low-valence variable-valence cation modification polycarboxylate superplasticizer master batch and a low temperature preparation method thereof. The modification master batch is used for an enterprise of additives in the non-heating production condition or a cold region, and with the limit of 40% of the mass of the master batch, the master batch is prepared from, by mass, 340-360 parts of a polyether macromonomer, 32.0-50.0 parts of acrylic acid, 1.3-3.0 parts of a chain transfer agent, 3.0-5.0 parts of an oxidizing agent, 0.55-3.50 parts of a reducing agent, 0.020-0.070 part of a low-valence variable-valence cation compound, 0.1-0.5 part of a stabilizer, 10-15 parts of sodium hydroxide and the balance water, wherein the total mass of all the synthesis raw materials is 1,000 parts. The synthesis polycarboxylate superplasticizer has the advantages that the polycarboxylate superplasticizer can be polymerized under the low temperature, side chain distribution is uniform, the molecular weight distribution range is wide, the water reduction rate of the master batch is high, and the adaptability is wide.

Description

technical field [0001] The invention relates to a polycarboxylate water-reducer for cement-based cementitious materials, which is suitable for non-heating production conditions or cold regional climates, and specifically relates to a low-valence variable cation modified polycarboxylate water-reducer parent very low temperature preparation method. Background technique [0002] With the proposal of the national green building materials strategy, the normal temperature synthesis technology of polycarboxylate superplasticizers has tended to be mature. The peroxide used in the synthetic heating process is abandoned as an initiator. The normal temperature synthesis mostly uses an oxidation-reduction system to reduce the activation energy of decomposition. The concept usually refers to 15 ~ 25 ℃. When the temperature is lower than 15°C, the common oxidation-reduction system is not enough to ensure the initiation effect. At this time, strong reducing agents such as chalk and sodium...

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Problems solved by technology

When the temperature is lower than 15°C, the common oxidation-reduction system is not enough to ensure the initiation effect. At this time, strong reducing agents such as chalk and sodium bicarbonate that can release a large amount of heat when contacting with water are often used, but the oxidizing agent-strong reducing agent system is in A large number of free radicals will be released in a short period of time, and the polymerization rate and chain growth rate are significantly greater than the chain termination rate. The mismatch between the above three will easily lead to the formation of disordered structures in the water reducer molecules. Due to the short half-life of the strong reducing agent in the middle and later stages of synthesis and the large consumption of acrylic acid in the early stage, the grafting of branch chains is chaotic and disorderly, and the effect of water reducing agent becomes poor.

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