Preparation method of vinyl acetate-acrylate copolymerization emulsion

Abstract

The invention discloses a preparation method of vinyl acetate-acrylate copolymerization emulsion, comprising the steps of adding 55-65 parts of water by weight, 0.01-4 parts of surfactant by weight, 0.5-2 parts of pH stabilizer by weight and 0.1-1 part of alkyl alcohol by weight into a reaction kettle with an agitator, a thermometer, a nitrogen tube and a reflux condenser, adding part of mixed monomers of mixed chain transfer agents, adequately emulsifying, raising temperature to a reaction temperature, adding part of initiators, reacting for 0.5 hour, and obtaining the seed emulsion when the emulsion has blue lights; dripping the rest mixed monomers into the reaction kettle with the seed emulsion, finishing dripping within 3 hours, synchronously supplementing the rest initiators, after finishing feeding, keeping the reaction temperature, reacting for 3 hours, raising temperature to 85 DEG C, continuously reacting for 0.5 hour so as to reduce the content of residual monomers, and then adding a neutralizing agent, adjusting the pH value of the emulsion to be neutral, cooling down and discharging material, and filtering to obtain the nanometer-sized emulsion. The obtained emulsion has a particle diameter smaller than 100nm and has excellent storage stability and other comprehensive performances.

Description

technical field [0001] The invention relates to a preparation method of nanometer vinyl acetate-acrylate copolymer emulsion, which belongs to the field of polymer synthesis. The copolymer emulsion is used in the fields of wood processing, fabric bonding, packaging materials and architectural decoration. technical background [0002] Vinyl acetate-acrylate copolymer emulsion is to use vinyl acetate and acrylate to copolymerize to improve the performance of the emulsion. The acrylate monomer can be selected according to the performance requirements. Usually, a certain amount of methacrylic acid is added as a functional monomer to improve the performance of the emulsion. Emulsion stability, paint film heat resistance, and the obtained copolymer emulsion. Because polyvinyl acetate and its copolymerized emulsion are water-dispersed, non-toxic, and environmentally friendly; they have the advantages of strong adhesion to porous materials such as wood, paper, cotton cloth, ceramics...

AI Technical Summary

Problems solved by technology

At present, nanometerization has been realized in pure acrylate emulsions or other modified acrylate emulsions such as polyurethane-modified acrylate emulsions, and has been well applied. However, due to the special nature of vinyl acetate monomers, vinyl acetate and its copolymer emulsions Sex has not yet been nanosized

The main reasons are: First, compared with acrylate monomers, vinyl acetate monomers have a relatively large solubility in water, so the nucleation in the water phase during the polymerization process is one of the nucleation methods that cannot be ignored. In the seed emulsion polymerization method, after the seed polymerization process is completed, there will still be new nucleation with the addition of monomers. Because of the existence of new nucleation, if the new nucleation cannot absorb enough dispersion stabilizer to stabilize, will result in an increase in particle size

The second, because vinyl acetate monomer has the existence of acetate group, therefore cause the initiator activity of this monomer to be lower, but once generate growth free radical, because the existence of ester bond can not stabilize the free radical of generation, thus cause growth free radical to have Very high reactivity, easy to transfer to monomers, polymer chains, and dispersion stabilizers, resulting in poor dispersion stability and increased particle size

However, due to the particularity of vinyl acetate monomer, there are still certain difficulties in the preparation of nanoscale emulsions.