Acrylate polymer is usually a copolymer formed by copolymerizing several acrylate monomers. The monomer composition determines the physical, chemical and mechanical properties of the polymer. There are three kinds of monomers for synthesizing acrylate copolymer: viscous monomer (soft monomer), cohesive monomer (hard monomer) and functional monomer (modified monomer).(1) viscous monomer (soft monomer)Viscous monomers contribute to adhesion and softness. Common ones include ethyl acrylate, butyl acrylate, 2- ethylhexyl acrylate, etc. The soft monomer has low glass transition temperature, which can improve the elasticity and flexibility of the adhesive film.(2) Cohesive monomer (hard monomer)Cohesive monomers such as methyl methacrylate, methyl acrylate, styrene, vinyl acetate and the like have higher glass transition temperature and polarity, and can improve the hardness, strength, oil resistance, solvent resistance, scratch resistance and adhesion performance of emulsion polymers.(3) functional monomer (modified monomer)The introduction of modified monomer can make the polymer film have some special properties, such as (meth) acrylic acid, (meth) hydroxyethyl acrylate, glycidyl methacrylate, N- methylolacrylamide, etc. Adding a small amount (usually, 3% 7% of such modified monomers) can greatly improve the cohesive strength, mechanical properties, heat resistance and aging resistance of the copolymer.