Preparation method of star polycarboxylic acid high-performance water reducing agent

Abstract

This invention relates to a method for preparing a star-shaped polycarboxylate superplasticizer by the first esterification step with polyol and (meth)acrylic acid as main reactants and the second polymerization step. In the first step, the star-shaped polymerizable active ends were synthesized by esterification between polyol and (meth)acrylic acid in the presence of catalyst. In the second step, the final star-shaped polycarboxylate superplasticizer was prepared by radical polymerization among the product obtained in first step, unsaturated polyoxyethylene ethers, molecular weight regulator and unsaturated carboxylic acid in the presence of initiator. The production process of this invention exhibits some characteristics including simple, easily controllable, high polymerization degree, low cost and pollution free. The star-shaped molecular structure of polycarboxylate superplasticizer can be achieved through synthesizing active “core” by esterification and “arm” by radical polymerization. It showed better cement paste fluidity and fluidity retention, which manifested as better adaptability to cement and application performance in concrete, than both traditional linear and comb-shaped polycarboxylate superplasticizer at common or lower dosage.

Description

technical field

[0001] The present invention relates to the technical field of a polycarboxylate high-performance water reducer for cement concrete, in particular to a polycarboxylate superplasticizer with a star structure synthesized by esterification of polyols and acrylic monomers to generate active cores and then copolymerized. The specific preparation method of performance water reducer. Background technique

[0002] In recent years, with the rapid development of the construction industry and the continuous improvement of the design level, people have put forward higher requirements for cement admixtures. In the past ten years, new technologies such as large formwork, slip form, pumped concrete, vacuum water-absorbing concrete, and shotcrete have appeared in the field of construction; in the supply of concrete, methods such as commercial concrete and centralized mixing have emerged; There are high-rise, super high-rise, long-span, folded plate, thin shell, frame light ...

Examples

Embodiment 1

[0025] First, 20.13g of trimethylolpropane was added to the reactor, the temperature was raised to 40°C, 0.02g of hydroquinone methyl ether, 38.74g of methacrylic acid, and 0.88g of sulfamic acid were successively added to the reactor, and each feeding interval Stir for 20 minutes, add 17.66g of toluene when the temperature rises to 80°C, continue to raise the temperature to 150°C for esterification reaction, separate the water obtained during the reaction, and remove the water-carrying agent by vacuuming after 2 hours of reaction , to obtain the esterification reaction product; take 0.23g of the esterification reaction product and add it to the reactor, then add 72.97g of water, raise the temperature to 50°C and stir for 30 minutes until it is evenly mixed, then add 50g of allyl polyoxygen to the reactor in turn Vinyl ether (molecular weight = 500), 0.46g mercaptoacetic acid, 10.81g acrylic acid, 3.8g initiator ammonium persulfate solution with a mass fraction of 30%, and the ...

Embodiment 2

[0027] After the polycarboxylate superplasticizer with a concentration of 40% obtained in Example 1 was stored at 6°C for 30 days, its implementation effect was measured.

Embodiment 3

[0029] First, 10.93g of mannitol was added to the reactor, the temperature was raised to 80°C, 2.16g of hydroquinone, 43.24g of acrylic acid, and 5.42g of p-toluenesulfonic acid were successively added to the reactor, and the stirring time between each addition was 5 minutes. When the temperature rises to 100°C, add 16.25g of cyclohexane, and continue to heat up to 140°C for esterification reaction. During the reaction, the water obtained from the reaction is separated out. After 3 hours of reaction, the water-carrying agent is removed by vacuuming to obtain the ester reaction product; take 0.53g esterification reaction product and join in the reactor, add 51.75g ​​water again, raise the temperature to 65 ℃ and stir for 10 minutes until it is mixed evenly, add 60g isobutenyl polyoxyethylene ether (molecular weight =3000), 3.04g n-dodecyl mercaptan, 0.6g acrylic acid and 4.09g maleic anhydride mixture, 142.87g mass fraction is 1% initiator ammonium persulfate solution, and the s...

technical field

[0001] The present invention relates to the technical field of a polycarboxylate high-performance water reducer for cement concrete, in particular to a polycarboxylate superplasticizer with a star structure synthesized by esterification of polyols and acrylic monomers to generate active cores and then copolymerized. The specific preparation method of performance water reducer. Background technique

[0002] In recent years, with the rapid development of the construction industry and the continuous improvement of the design level, people have put forward higher requirements for cement admixtures. In the past ten years, new technologies such as large formwork, slip form, pumped concrete, vacuum water-absorbing concrete, and shotcrete have appeared in the field of construction; in the supply of concrete, methods such as commercial concrete and centralized mixing have emerged; There are high-rise, super high-rise, long-span, folded plate, thin shell, frame light ...

Examples

Embodiment 1

[0025] First, 20.13g of trimethylolpropane was added to the reactor, the temperature was raised to 40°C, 0.02g of hydroquinone methyl ether, 38.74g of methacrylic acid, and 0.88g of sulfamic acid were successively added to the reactor, and each feeding interval Stir for 20 minutes, add 17.66g of toluene when the temperature rises to 80°C, continue to raise the temperature to 150°C for esterification reaction, separate the water obtained during the reaction, and remove the water-carrying agent by vacuuming after 2 hours of reaction , to obtain the esterification reaction product; take 0.23g of the esterification reaction product and add it to the reactor, then add 72.97g of water, raise the temperature to 50°C and stir for 30 minutes until it is evenly mixed, then add 50g of allyl polyoxygen to the reactor in turn Vinyl ether (molecular weight = 500), 0.46g mercaptoacetic acid, 10.81g acrylic acid, 3.8g initiator ammonium persulfate solution with a mass fraction of 30%, and the ...

Embodiment 2

[0027] After the polycarboxylate superplasticizer with a concentration of 40% obtained in Example 1 was stored at 6°C for 30 days, its implementation effect was measured.

Embodiment 3

[0029] First, 10.93g of mannitol was added to the reactor, the temperature was raised to 80°C, 2.16g of hydroquinone, 43.24g of acrylic acid, and 5.42g of p-toluenesulfonic acid were successively added to the reactor, and the stirring time between each addition was 5 minutes. When the temperature rises to 100°C, add 16.25g of cyclohexane, and continue to heat up to 140°C for esterification reaction. During the reaction, the water obtained from the reaction is separated out. After 3 hours of reaction, the water-carrying agent is removed by vacuuming to obtain the ester reaction product; take 0.53g esterification reaction product and join in the reactor, add 51.75g ​​water again, raise the temperature to 65 ℃ and stir for 10 minutes until it is mixed evenly, add 60g isobutenyl polyoxyethylene ether (molecular weight =3000), 3.04g n-dodecyl mercaptan, 0.6g acrylic acid and 4.09g maleic anhydride mixture, 142.87g mass fraction is 1% initiator ammonium persulfate solution, and the s...

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