Study On Preparation And Properties Of UV-curable Adhesive

The ultraviolet cured adhesive is one of fine polymers of energy conservationand environmental protection which was developed in1970s. The advantages ofquick-solidification, non-contamination, excellent-adhesive performance andsafety-production have drawn enormous attention in recent years. In China, becauseof people’s environmental protection consciousness and the enactment of energyconservation and emission reduction regulations, development and applications ofultraviolet cured adhesive are more and more concerned as environment-friendly“green technology”, of which the market share is growing.In this paper urethane acrylates (PUA) of prepolymers were prepared by bulkpolymerization, and the synthesis process was discussed in detail. UV adhesives usedon glass substrate and materials low surface energy (such as PET) were confected.The elemental formulas of the adhesives were studied and the factors of adhesivebonding performance and curing rate were discussed.Urethane acrylates prepolymer were synthesized by polyols, isocyanate, methylmethacrylate hydroxyl ethyl ester as raw materials. The synthesis technology wasinvestigated including the influences of reaction temperature, catalyst dosage and-NCO/-OH on the prepolymer performance and the optimum synthesis method wasgiven. The results showed that the reaction rate was fast and the prepolymers had ahigh doublebond content while keeping the second step temperature at50-55℃,NCO/OH ratio at0.9:1.1and catalyst content at0.3-0.6%. The surface tension ofprepolymers could be as low as38.4mN/m.Formula design of UV adhesive used for bonding glass was conducted andcomprehensive performance was obtained. The results showed when the prepolymers1#:2#=2:1(quality score,50%), diluent monomers IBOA: TPGDA=7:3(45%),photoinitiators TPO (4%to5%), silane coupling agent (0.5%-1%), the bondingperformances of adhesive are best, approaching substrate fracture. The adhesive wasfound with surface tension of30.4mN/m, curing rate of2.6s, adhesive attraction ofgrade1, light transmittance of90.4%and fog degree of0.1%. It exhibits not onlystrong physical and mechanical performance but also excellent optical properties.The formulation of UV adhesive for bonding PET with low surface energy was studied and the influence factors of bonding performance and curing rate wereexamined. The thermo-gravimetric measurement and acid/alkali resistance ofsolidified film were performed. The surfaces of PET chips before and after adhesivewere scanned by SEM. The results showed that when the prepolymers ratio2#:CN996j75was2:3with a dosage from50%to60%, active diluent monomer ratioIBOA:HDDA was1:1, photoinitiators ratio TPO:907was1:1with a dosage from4%to5%, dosage of silane coupling agent KH550was control between0.4%and0.5%,the adhesive curing rate was the fastest and the bonding strength was great,approaching substrate fracture. The bonding strength of adhesive can be improved bytreating the bonding surface with ethanol/alkali. The acid resistance of UV curing gluefilm is better than its alkalis resistance. The film exhibit good heat stability with thehighest working temperature of166.4℃. The adhesion capacity of UV adhesive forbonding PET was also confirmed by SEM.