Synthesis Of Acrylate Pressure Sensitive Adhesives With Core-shell Structure

Water-based acrylic pressure-sensitive adhesives(PSA)are widely used in packaging,aerospace,furniture appliances,construction and advertising consumables,and medical applications because of their simple production process,good adhesive properties,and environmental friendliness.PSA usually undergo long-term exposure to ultraviolet light,rain,and other complicated environments during use,which requires that they have high cohesive strength and good weatherability.The highly water-resistant whitening of PSA,in particular hot water or hot steam whitening,is necessary in some fields of application.Hydrophilic emulsifiers and wetting agents in emulsion-type acrylate PSA make their water resistance properties,especially high temperature and high humidity aging properties,poor.At the same time,due to the linear molecular structure of acrylate copolymers,cross-linking density is low.The cohesive strength is poor,and the molecular structure is more easily destroyed under moist heat conditions,thereby affecting its mechanical properties and performance.Therefore,from the perspective of molecular structure,designing a new type of structural water-based acrylic heat-resistant aging pressure-sensitive adhesives not only has high academic value,but also can meet the extensive needs of industrial applications.In this study,sodium dodecyl sulfate(SDS)was used as emulsifier,isooctyl acrylate,butyl acrylate,methyl methacrylate and itaconic acid(ITA)as reaction monomers to synthesize a latex with a particle size of 1 μm.As a nuclear emulsion;compounded with CO-436 and DB-45 2:1 as an emulsifier with isooctyl acrylate,butyl acrylate,methyl methacrylate,acrylamide(AM)or dehydrated glycerol methacrylate(GMA)synthesizes a latex with a particle size of 80 nm as the shell latex for the reaction monomers;the polymerization process of the two emulsions,the amount of functional monomer added,and the mixing ratio were studied for the new emulsion cross-linking of the last two emulsions.The effects of the mechanical properties and moisture and heat aging resistance of the core-shell structural emulsions were evaluated,and the prepared core-shell emulsion structures were characterized.IR spectra showed that the functional groups were cross-linked.The particle size distribution characterized the size of the core and shell emulsions at 1 μm and 80 nm respectively.Differential scanning calorimetry showed that the core-shell structure emulsion polymer contained two glass transition temperatures.Scanning electron microscopy characterized the core-shell cross-linked structure.The study found that when SDS was added in an amount of 1%(based on the total monomer mass),ITA was added at 7 ‰ and 500 rpm was used to prepare the core emulsion;the total amount of CO-436 and DB-45 was 7%,AM or GMA.Adding the amount of 4 ‰,1200 rpm to prepare the shell emulsion;when the ratio of shell to core is 20:1,the obtained core-shell latex liquid has the best resistance to moist heat aging.In addition,the system with GMA added has better moisture and heat aging resistance than the system with AM.