Tackifying action

M. Sherriff, R.W. Knibbs, and P.G. Langley, "Mechanism for the Action of Tackifying Resins in Pressure-Sensitive Adhesives," J. Appl. Polym. Sci., 3423... 

Stearic acid is a usual processing aid in butyl rubber formulations, acting as lubricant and minimizing mill sticking apart from this action, it also plays the role of activator in the curing system. Hydrocarbon or phenolic tackifying resins are sometimes provided in compounds to assist the adhesion in confection or splicing. 

Figures 5.5 and 5.6 illustrate the potential effect of slip agents on performance of antiblocking agents and vice versa. Further details on this subject can be found in Section 8.3. Other additives which potentially affect blocking force primarily include plasticizers and tackifiers, but stabilizers, lubricants, antistatics, surface agents, and cmatives may also potentially affect blocking. Tackifiers are intentionally added to increase blocking, and as such are not the subject of this book. Plasticizers are frequently the very reason to use antiblocking additives, as, for example, in the case of soft polyvinylchloride. A monographic book on plasticizers contains detailed information on plasticizers and their action.

Tackifiers increase the tackiness and the setting speed of adhesives. They increase tackiness by softening the polyvinyl acetate polymer, both in the wet and in the dry adhesive film. They accelerate setting speed by raising the total solids content of the emulsion. This action has the twofold result of crowding the aqueous phase and making the emulsion less mechanically stable. 

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