Preparation Of Rosin Modified Acrylate Block Copolvmer Via RAFT Emulsion Polymerization And Its Application In Water-based Pressure-Sensitive Adhesive

Acrylate emulsion has been widely used in adhesives and other fields because of its simple and convenient preparation process,low production cost and little environmental pollution.To further improve the overall performance of acrylic emulsion pressure-sensitive adhesive(PSA),especially the adhesion to difficult-to-stick materials(polyethylene,polypropylene,etc.),tackifying resins(rosin,etc.)are often added to improve PSA and adherends wettability,thereby increasing their tack and peel strength.China has very rich rosin resources,the use of rosin and its derivatives to modify acrylate emulsion PSA not only opens a new way for the research and utilization of rosin deep processing but also provides a new approach to improve the overall performance of acrylate emulsion PSA.Meanwhile,these researches expand the application of acrylic emulsion PSA.In this paper,RAFT emulsion polymerization method was used to prepare rosin modified acrylate emulsion PSA.Poly(nBA-random-DAEMA)random copolymers and PSt-b-Poly(nBA-random-DAEMA)-b-PSt block copolymer were designed and synthesized,which were used as the base resin of acrylate emulsion PSA.The effect of copolymerization of rosin-based monomer(Dehydroabietic Ethyl Methacrylate,DAEMA)on the macro-adhesive properties of acrylate emulsion PSA was studied.The main results obtained are as follows:1.A series of Poly(nBA-random-DAEMA)random copolymers and PSt-b-Poly(nBA-random-DAEMA)-b-PSt block copolymers were successfully synthesized through RAFT emulsion polymerization.The conversion rate of copolymer was greater than 90%and the emulsion stability was good.The actual molecular weight of the copolymer was basically consistent with the theoretical molecular weight,and the molecular weight distribution was narrow.The random copolymer PDI<2 and the block copolymer PDI<3.6.2.In the study of the film formation process of rosin-modified acrylate emulsion,it was found that when the amount of surfynol 104E was 0.13 wt%of the emulsion,the surface tension of the emulsion decreased from 72 mN/m to 52 mN/m.At this time,the emulsion began to exhibit the wetting performance on the PET film.Drying at room temperature or 120? had little effect on the adhesive properties of the dry film.3.The effect of DAEMA on the macro-adhesive properties of triblock copolymer SB AS was explored.The peel strength of the SBAS emulsion PSA was significantly improved with the increase of DAEMA block content.When the block content of DAEMA was 3.33 wt%,the peel strength of the PSA reached 8.9 N/24mm,which was 1.4 times higher than the peel strength before modification.With the increase of the block content of DAEMA,the tack was maintained at about 3#,and the shear time was more than 2 h.4.The effect of DAEMA on the macro-adhesive properties of homopolymer PnBA was discussed.Both the shear time and the peel strength of the SBAS emulsion PSA were significantly improved with the increase of DAEMA block content.When the block content of DAEMA was 6.67 wt%,the shear time of PSA reached 5m58s,which was 5m21s longer than that before modification,and the peel strength of the PSA reached 2.4 N/24mm,which was 1.2 times higher than the peel strength before modification.With the increase of the block content of DAEMA,the tack was maintained at about 9#.5.The effect of DAEMA on the macro-adhesive properties of SBAS and PnBA mixtures was researched.Whether the DAEMA was added to SBAS or PnBA,as the block content of DAEMA increased,the tack of the acrylate emulsion PSA hardly changed,while the shear time and peel strength increased.When the block content of DAEMA in SBAS was 2.67 wt%and the block content of DAEMA in PnBA was 5 wt%,the shear time of PSA reached 7m22s,which was 4m30s longer than that before modification,and the peel strength of the PSA reached 3.2 N/24mm,which was 0.6 times higher than the peel strength before modification.6.The modification effects of DAEMA and commercial rosins on acrylate emulsion PSAs were compared,and it was found that the copolymerization modification effect of DAEMA is better than that of commercial rosins.Commercial rosins were often used to improve the mobility of the copolymer,thereby increasing the tack.Unlike the Commercial rosins,the DAEMA not only improved the tack of the PSA,but also significantly improved the shear time and peel strength.The comprehensive performance of the rosin-modified PSA was more excellent,which may benefit from the significant influence of the molecular-level blending structure on the performance of the PSA.