Preparation And Properties Study Of Stearyl Acrylate Copolymer Through Emulsion Polymerization

Acrylate copolymer emulsion is very easily to obtain through conventional emulsion polymerization.Because of their excellent performance and environment friendly,they have been widely used in coating materials,adhesives,textile finishing coatings as well as other fields for decades.Long-chain alkyl acrylate copolymer,not only has super hydrophobicity,extremely low surface energy,but also have much better‘vapor permeability’than commercial acrylic copolymer latices,which is favored in the application of textile finishing coatings and non-silicon release agents.However,due to its strong hydrophobicity,long-chain alkyl acrylate monomers are difficult to achieve"monomer droplets→water phase→micelles or latex particles"diffusion during the emulsion polymerization process,resulting in a low monomer conversion percentage,it is difficult to exceed 50%,which limits the applications of acrylic copolymer latices containing long-chain alkyl acrylate.In this paper,a long carbon chain emulsifier is used as main emulsifier,through the hydrophobic interaction between long carbon chain emulsifier and stearyl acrylate（SA）,SA monomer was’ferried’from monomer droplet to micelle or latex particle surface to assist it to successfully realize emulsion copolymerization with other acrylate monomers.The release property and extinction property of stearyl acrylate copolymer latex film were explored,and the novel latex products are expected to be applied in the release agent and extinction coating.The main work of this paper is as follows:（1）Due to the high boiling point of SA（400.2°C）.The determination of its true conversion rate can no longer follow the existing national standard for determination（drying weight loss method）,and for this problem,this paper first compares the accuracy and convenience of three monomer conversion determination methods（drying weight loss method,Soxhlet extraction method and ¹HNMR calculation method）.The results showed that Soxhlet extraction was more suitable for the determination of monomer conversion during emulsion polymerization of high boiling point monomers.（2）In order to facilitate the study of emulsion polymerization containing SA,styrene monomer was introduced into the emulsion polymerization system for copolymerization.Under the combined action of long carbon chain anionic emulsifier N-3203N and nonionic emulsifier N-390,a pre-emulsification semi-continuous emulsion polymerization process was used to prepare styrene-acrylate emulsion copolymer.The effects of emulsifier dosage（N-390 dosage remained unchanged,and N-3203N dosage changed）and initiator dosage on the stability of emulsion polymerization and monomer conversion were investigated in detail.The results showed that when the dosage of N-3203N was 4 wt%and the dosage of APS was 0.6 wt%,the emulsion polymerization stability was the best,and the SA conversion percentage could reach 86.92%.（3）Based on the study of SA participating in styrene-acrylate emulsion copolymerization,butyl acrylate,methyl methacrylate,stearyl acrylate and acrylic acid are used as monomers,and long carbon chain emulsifiers N-3203N and N-390 are used as compound emulsification agents,using APS as initiator and Na HCO₃as p H buffer,a pure-acrylate emulsion copolymer with good flexibility,good polymerization stability and high SA conversion was successfully prepared by pre-emulsification semi-continuous emulsion polymerization process.The copolymers were characterized by FTIR,DSC,TG and XRD.Continuously improving the polymerization conditions to improve the polymerization stability,the results show that:when the amount of N-3203N is 4 wt%,the amount of APS is 0.5 wt%,and the amount of Na HCO₃is 0.2 wt%,the obtained emulsion has the best polymerization stability and the highest monomer conversion percentage.At this time,the coagulation percentage of the polymerization process reached a minimum of1.27%,and the SA conversion percentage can reached to 83.98%.（4）The above-mentioned pure acrylic emulsion copolymer was used in the release agent and extinction coating,and the isolation performance and extinction performance of the copolymer film were studied.With the increase of SA content,the surface tension and gloss of the copolymer latex film and the 180°peel strength between the tape and the latex film decreased significantly.When the SA content increased from 0 wt%to 30 wt%,the surface tension of the latex film decreased from 38 m N/m to 32 m N/m,the180°peel strength of the tape on the latex film decreased from 8.6 N/24mm to0 N/24mm,and the gloss decreased from 88.7°to 47.3°.The results show that the introduction of SA can improve the isolation performance and extinction performance of acrylate copolymer latex film,and the obtained latex is expected to be used for the preparation of release agent and extinction coating.