Multifunctional carboxylic-acid comb-shape graft copolymer concrete superplasticizer

Abstract

The multifunctional super concrete plasticizing agent of carboxylic acid comb grafting copolymer is prepared through the water free radical copolymerization of the following monomers: monomer A with the general expression I in 10-40 wt%, monomer B with the general expression II in 30-70 wt%, monomer C with the general expression III in 10-50 wt%, monomer D with the general expression IV in 3-15 wt%, monomer F with the general expression VI in 0-15 wt%, and reactive defoaming agent E in 0.2-2 wt% of the sum of foregoing five kinds of monomer. The present invention can reduce the shrinkage of concrete, and has good adaptability on cement and admixture material, good dispersivity and slump maintaining performance, high weeping resistance and resolution resistance, small pumping drag, product yield near 100 % and no waste produced in the production process.

Description

technical field [0001] The invention relates to a multifunctional carboxylic acid comb-shaped graft copolymer that can be used as a concrete superplasticizer and a preparation method thereof, belonging to the technical field of concrete admixtures Background technique [0002] Concrete is a very widely used structural material in civil engineering, construction, water conservancy and many projects. In modern building construction, ready-mixed concrete has accelerated the construction progress and With the improvement of engineering quality, the application is becoming more and more common, and concrete superplasticizer is the fifth component that is indispensable for preparing ready-mixed concrete. [0003] Concrete superplasticizer, also known as high-efficiency water reducer, mainly plays three different roles in concrete production technology: ① Improve the workability of concrete construction, reduce physical labor intensity, and facilitate mechanization without changing...

AI Technical Summary

Problems solved by technology

EP1304314, US5911820, US6444780 use mercaptoethanol, dodecyl mercaptan and mercaptopropionic acid to prepare low-molecular-weight water-based polymers as chain transfer agents, but mercaptoethanol and dodecyl mercaptan have stench and pollute the environment, while mercaptopropionic acid is very expensive Expensive, and these substances do not function as necessary components of the product

In addition, polymerize in a water-isopropanol mixed solvent, and use isopropanol to control the molecular weight of the product. This method requires a cumbersome post-treatment process for removing isopropanol. The part of isopropanol remaining in the copolymer not only has Odor, and will affect the application performance of the product

[0009] In addition, a concrete superplasticizer with excellent performance must have both good dispersibility and good dispersibility retention ability. CN1261599 discloses the synthesis of ethyl vinyl ether-maleic anhydride copolymer in methyl ethyl ketone or tetrahydrofuran medium. Grafting with polyether in a dehydrating solvent, the product has good slump retention performance, but the dispersion performance is not good, and organic solvent is used as the reaction medium, which is not only uneconomical but also not conducive to environmental protection

[0010] CN1058474 has reported a kind of new dispersive composition that is used for the excellent slump loss characteristic of cement, and this composition is by alkenyl ether, dialkenyl ether and maleic anhydride as monomer, with Azobisisobutyronitrile is polymerized in toluene solvent as an initiator. The product has good slump retention ability, but the dispersion performance is not very satisfactory, and the production process is not conducive to environmental protection

[0011] EP0924174 has synthesized different polymers with two kinds of branched chains with different lengths. The polymer with long branched chains has good dispersion due to the large steric hindrance, but the slump retention is not good. Chain copolymers have good slump retention performance, but poor dispersion

When two different copolymers are mixed in different proportions, the composite has both a certain dispersion and a certain slump retention ability, but its dispersibility and slump retention ability are far from enough

[0012] US5362829 has synthesized a copolymer with two different branch chains of different lengths, wherein the long branch chain provides dispersibility, while the short branch chain provides slump retention capacity, but the number of EO repeating units of the longest branch chain increased by this patent Also only 23, so the dispersion is not too good

[0013] EP1138697, US5583183, US5703174, US5633298, and US5393343 have reported using expensive primary amino-terminated monomethyl polyether as a raw material, utilizing active primary amino groups and carboxyl groups to carry out grafting reactions, but the product price is relatively expensive, which is not conducive to Promote

[0014] In addition, in order to solve the slump loss of concrete, US5362324 and US5661206 have reported the synthesis of ester crosslinked bodies, which have good slump properties due to chain scission and molecular weight reduction under the alkaline medium of cement. High degree of retention, but the dispersion is not very good

[0015] To sum up, there are many problems about polycarboxylate superplasticizers at present. The synthesis process of these products is not satisfactory, it is not clean and economical, and its application performance is not completely satisfactory. Relatively single, although some products have good dispersibility, but the dispersibility retention ability is not good, some products have a certain slump retention ability, but the dispersibility is not good, and the price is very expensive

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