Study On The Alkali-Soluble Resin Of Methacrylic Acid And Methyl Methacrylate As Stabilizer In Butyl Acrylate And Butyl Methacrylate Emulsion Polymerization

An alkali-soluble resin(ASR)is a special type of copolymer that can be classified as anionic ionomers of molecular weight ranging from 500-20000.It is able to stabilize particles via the electrosteric mechanism.Use of alkali-soluble resin in emulsion polymerization imparts Newtonian flow behaviour,excellent mechanical stability,good pigment dispersity and excellent wetting properties to the latexes,which makes them suitable for use in the printing inks.However,for all the papers published so far,the ASR used contains labile C-H bondsBased on methyl methacrylate(MMA),methylacrylic acid(MAA)as the main monomer,azodiisobutyronitrile(AIBN)as polymerization initiator,isopropyl alcohol as the reaction medium,ethyl hexyl thioglycolate(EHTG)as chain transfer agent.An ASR without labile C-H bonds was synthesized by polymeriation at 80℃.The effects of alkali-soluble resins(ASR)as colloidal stabilizers in emulsion homopolymerizations of butyl acrylate(BA)and butyl methacrylate(BMA)have been investigated using ASR synthesized by solution polymerization.For BA and BMA emulsion polymerizations with solution ASR,BA and BMA as the monomer,ASR as stabilizer,sodium dodecyl sulfate(SDS)as the stabilizer,ammonia as neutralizing agent,sodium persulfate(NaPS)as initiator,the reaction was carried out at 80℃.Two different processes were used:(1)all ASR solution was present in the reaction vessel at the start of the reaction and all the monomers were fed continuously,and(2)20 wt%of the total ASR solution was present in the reaction vessel at the start of the reaction and the remaining 80 wt%ASR solution was fed simultaneously with all the monomer.The experimental results showed that all the particles in the emulsion polymerization of butyl acrylate(BA)and butyl methacrylate(BMA)by using alkali-soluble resins(ASR)underwent nucleation-growth process,and the dispersion was mono-dispersed without secondary nucleation.Based on the simplified model calculation,it was found that the rate of BA/BMA z-mer free radical entering the ASR aggregate in the aqueous phase was 105-106 times of the continuously increasing rate,and particles are mainly nucleated from radical entry into ASR aggregates,and the nucleation mechanism was similar to micellar nucleation,and the ASR aggregate was the main loci of emulsion polymerization nucleation.