A kind of four-arm star block polycarboxylic acid superplasticizer and its preparation method and application

Abstract

The invention discloses a four-arm star-shaped block polycarboxylic acid superplasticizer and its preparation method and application. The superplasticizer is first capped with a halogen-containing carboxylic acid derivative having four hydroxyl molecules, and then A star-shaped four-arm block superplasticizer is finally synthesized by acidolysis, separation and purification of polymers with halogen-terminated four-arm molecules as the structural core and non-traditional unsaturated carboxylic acid derivatives as arms. The invention does not use traditional unsaturated carboxylic acid polymerization, can improve the controllability of structure, and reduce the irritation of unsaturated carboxylic acid in production. The water reducer synthesized by the invention has excellent molecular structure controllability. The product of the invention is solid, has low dosage, high dispersibility, high fluidity, and has the characteristics of convenient transportation and storage, low water absorption and corrosiveness.

Description

technical field [0001] The invention belongs to the field of superplasticizers, in particular to a four-arm star-shaped block polycarboxylic acid superplasticizer and a preparation method and application thereof. Background technique [0002] Because polycarboxylate superplasticizer (PCE) has the characteristics of low dosage and high water reduction rate (>40%), it can significantly improve the working performance, mechanical properties and durability of concrete, and has become a high-performance or ultra-high-performance concrete. One of the essential components in mix design. [0003] At present, the industrially produced polycarboxylic acid-based high-performance superplasticizers are mainly composed of unsaturated monomers containing carboxyl groups, unsaturated polyethers and other monomers through free radical copolymerization. Multi-branched comb-structured polymers of acid radicals, ammonium radicals and polyether macromonomers. [0004] The star-shaped carbox...

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Problems solved by technology

[0006] For example, Shou Chongqi et al. (2011) synthesized N-hydroxyethyl-3-amino-N,N-propionic acid methyl ester, then introduced bromine-containing terminal groups through transesterification, and finally initiated atom transfer radical polymerization , to obtain a four-arm polycarboxylate superplasticizer, but its disadvantages are also obvious. The non-conjugated bromine-containing end group obtained by transesterification has a low activity of the central initiator to initiate polymerization, resulting in a polymerization process in the The central molecule initiates less, and the thermally induced self-polymerization occupies a certain amount, which cannot give full play to the steric hindrance advantages provided by the star initiator.

[0007] Pei Jikai et al. (2018) used double metal cyanide complexes to catalyze the polymerization of ethylene oxide to obtain high-molecular-weight isobutylene-based polyoxyethylene ether, and then copolymerized with acrylic acid to obtain star-shaped side chains. The polymerization method used is still traditional Free radical copolymerization, it is difficult to design the structure of the polymer, and the reactivity ratio still exists

[0008] Chinese patent ZL 201610122451.1 discloses a preparation method of star-shaped polycarboxylic acid-based water reducer, using polyols to carry out esterification reactions with carboxyl-containing trithioesters, dithioacids, etc. The central compound of the transfer group is then copolymerized with unsaturated acid and polyether to obtain a polycarboxylate water reducer with controllable structure, but due to the excessive amount of alkyl groups such as trithioester used in the preparation, the hydrophobicity Strong, low solubility in water, difficult to regulate chain transfer

[0009] Chinese patent ZL 201610122454.5 discloses a preparation method of a star-shaped polycarboxylate water reducer with controllable molecular structure. A compound with a multi-halogen end group, and then initiates atom transfer radical polymerization on it, and sodium methacryl sulfonate, allyl polyoxyethylene ether, allyl sodium sulfonate, vinylbenzene sulfonate, methyl Sodium allyl sulfonate, sodium methoxyallyl sulfonate, potassium allyl sulfonate, potassium styrene sulfonate, potassium vinyl sulfonate, potassium methallyl sulfonate, methallyl Potassium oxysulfonate, etc. are copolymerized into copolymers, but limited to the solubility of different monomers and initiators, and the complexation of groups on the polymer to metal ions, the molecular structure can be regulated, but the synthesized star Type polycarboxylate superplasticizer has the advantages of low dosage, high water reducing rate, small slump and good cement compatibility.

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