Influence Of Surfactants And Functional Monomer On The Process And Performance Of Vinyl Acetate-acrylate Emulsion Polymerization

Vinyl acetate-acrylate latex presents advantages of being low cost, good leveling and good workability etc and thus has been applied in various fields. To abtain vinyl acetate-acrylate latex, Alkyl phenol ethoxylates (APEO) has been normally used in preparation. However, many countries have prohibited using alkyl phenol ethoxylates (APEO) due to their toxicity and biodegradability. Substitutions of green surfactants for APEO become a research domain. In this article, choosing environmental friendly alcohol ethoxylates (AEO-9), sulfosuccinic acid alkyl polyoxyethylene monoester disodium salt (A-102) and sorbitan monooleate (Tween 80) instead of traditional alkyl phenol ethoxylates (APEO) as surfactants in polymerization to obtain green emulsion. The effects of these surfactants and functional monomer on properties of emulsion and latex film were explored. Modifying the type and ratio of functional monomer to improve the properties of vinyl acetate-acrylate latex, as well as to make up for the shortcoming of green surfactants.The optimum conditions for vinyl acetate-acrylate emulsion polymerization was prepared by pre-emulsified technique, adopting semi-continuous seeded emulsion polymerization methods. Reaction temperature is 80℃. Stirring speed is 250 r/min and monomer addition time is 3 h. The appropriate amount of the initiator and buffer are 7.5‰and 4‰.The results show that the structures of the surfactants affect the properties of latex film greatly even if they have the same HLB value. Due to its hydrophobic benzene ring, the latex film prepared by NP-10/SDS obtained low water absorption and film surface energy. However, green surfactants such as AEO-9/SDS and A-102/SDS can’t reach these excellent performances. In the practical production, we can add some hydrophobic monomer to improve the properties of latex film prepared by AEO-9/SDS. When the ratio of hydrophilic functional monomer is AA (acrylic acid): HEA (hydroxyethyl acrylate) = 1.25: 2, the latex prepared by NP-10/SDS of which average particle size is 194.6 nm, while surface energy and water absorption of latex film are 35.3256 mJ/m2 and 15.32 %. After using AEO-9/SDS as surfactants, the average particle size is 142.5 nm, while surface energy and water absorption of latex film are 48.6117 mJ/m2 and 40.89 %. It is found that the best ratio of functional monomer is AA: HEA: V (alkyl acrylate with long chain) = 1.25: 2: 5. In this ratio the latex prepared by AEO-9/SDS presents average particle size of being 114.8 nm, and its surface energy and water absorption of latex film are 38.3143 mJ/m2 and 15.28 %.