High-branch type polyvinyl alcohol-acrylamide graft copolymer, preparing method thereof and applications of the copolymer

Abstract

The invention relates to a preparing method of a high-branch type polyvinyl alcohol-acrylamide graft copolymer. The preparing method includes: dissolving polyvinyl alcohol with water, feeding nitrogen, cooling, adding a catalyst, reacting for 10-30 min, adding dropwise a monomer mixture solution with the adding time being controlled to be 30-90 min and the reaction temperature during addition being controlled to be 65-95 DEG C, reacting at 85-95 DEG C for 20-30 min after the addition is finished, adding the catalyst, reacting at 80-95 DEG C for 15-25 min, adding the catalyst, sampling in the reaction process and measuring viscosity, adding a terminating agent when the viscosity at 25 DEG C reaches 1500-15000 mPa*s to stop the reaction, and adjusting the solid content. The graft copolymer has characteristics of high molecular weight, more branches, low viscosity, less gel, good retention property, and high interference resistance to hetero-ion, and can achieve satisfied enhancing effects even when being used as a papermaking dry strength agent in a bad high-temperature high-conductivity environment for manufacturing paper with pulp.

Description

technical field [0001] The invention relates to the fields of polymer synthesis and dry strength agents, in particular to a highly branched polyvinyl alcohol-acrylamide graft copolymer, its preparation method and its application as a dry strength agent. Background technique [0002] In view of the current situation that my country's papermaking raw materials mainly use waste paper pulp, coupled with being forced by the national policy of energy saving, emission reduction and environmental protection, papermaking enterprises have to vigorously promote clean production, resulting in closed circulation of white water, serious accumulation of garbage and impurities in the system, high temperature and high conductivity. Under the system, the amount of additives is large, the retention rate is low, and the paper strength is poor. In order to improve retention and improve paper quality, paper mills use dry strength agents in large quantities. [0003] Dry strength agents are an imp...

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Problems solved by technology

[0007] Chinese patent publication CN103333352A discloses a preparation method of a cross-linked graft modified polyvinyl alcohol surface enhancer, which is to mix polyvinyl alcohol with water to obtain a polyvinyl alcohol aqueous solution; heat the aqueous solution, and add ketone carbonyl-containing Vinyl monomers, cationic monomers, vinyl monomers containing long side chain groups, self-crosslinking monomers and other types of vinyl monomers, then add initiator aqueous solution dropwise, and adjust the pH with alkali after polymerization , add hydrazine or its derivatives and stir evenly to obtain a cross-linked graft modified polyvinyl alcohol surface enhancer; the strengthener and fiber bonding points obtained in this patent are less, and the retention rate is low, so it is not suitable for adding in pulp

The above patents all use the method of adding a cross-linking agent to prepare a branched or cross-linked dry strength agent. There is a common problem: the polymerization is difficult to control after adding a cross-linking agent, and the degree of branching is generally not high, because cross-linking Adding too many molecular chains of the linking agent is easy to cross-link the gel, and the water solubility becomes poor; while the cross-linking agent is added with less branched chains, the purpose of high branching cannot be achieved, and the reinforcing effect is poor

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