The Rheological Property And Adhesion Process Of Polyolefin-Based Hot Melt Medical Adhesive

Polyolefin hot melt medical adhesive applied for bonding polyolefin medical material and pats was prepared by melt blending random copolymerized polypropylene (PPR), viscosity modifiers, antioxidants and inorganic fillers in certain proportion. This paper mainly focuses on the melt viscosity of the hot melt adhesive and its application in bonding polyolefin medical parts. A proper adhesion process is developed.Be based on melt viscosity of the hot melt adhesive, the effect of shear rate and temperature on the melt viscosity of the main polymer in the hot melt adhesive was investigated firstly. The results show that as the shear rate increases from 100s-1, the melt viscosity decreases rapidly starting from 2100Pa·s and then stabilized at about 64Pa·s, with the temperature increasing, the melt viscosity of the main polymer reduces at first and then rise slightly, with the lowest point at about 165℃. The viscosity at 165℃ was 52Pa·s at 5000s-1 shear rate and 27Pa-s at 10000s-1 shear rate. The effects of viscosity modifiers, antioxidants and inorganic fillers on the rheological property of the hot melt adhesive were also investigated. The effect of additive amount of the adhesive components on the property of the polyolefin hot melt adhesive have been revealed:with the increase of addition amount of viscosity modifiers, the shear viscosity of hot melt adhesive and melt stiffness decreased, as the amount of antioxidant increased, the shear viscosity and melt stiffness of hot melt adhesive showed almost no change under conditions investigated, the addition of inorganic fillers (organically modified montmorillonite) led to almost no change in the shear viscosity of hot melt adhesive but caused an increase in the melt stiffness of the adhesive. Such an increase in the melt stiffness of the polyolefin hot melt adhesive provides a better thermo-resistance of the hot melt adhesive during steam sterilization.According to rheological property of hot melt adhesive, the adhesion process was researched. Adhesive-bonded joints with different structures were designed and produced by 3-D printing. Subuliform adhesive-bonded joint was found to be unique in connecting the plastic medical tubes with the same diameter or even different diameters in a certain range. To overcome the difficulty of apply the hot melt adhesive due to its high melt viscosity, a pre-assembling and heating approach for tube adhesion/connection was built up, i.e. assembling the bonding joint, hot melt adhesive tubing film and polypropylene catheter together at room temperature; then the hot melt adhesive film was allowed to melt by heating the overall system. The adhesion process was completed after the system was subjected to cooling at ambient temperature. This method allows finishing simultaneously the adhesion/connection and steam sterilization of medical tubes in one step.A variety of methods were employed to evaluate the adhesive bonding performance of the hot-melt adhesive. Excellent bonding strength and sealing performance of the hot melt adhesive for polypropylene medical devices was verified. The hot melt adhesive was found to fully meet the medical requirements for real application.