Fast-Curing Systems

Highly reactive two-component epoxy adhesives have several advantages. These adhesives can come to a practical handling strength in minutes at room temperatures and can develop useful bond strengths at ambient temperatures as low as —20°C. The various uses for these adhesives include 

Bonding difficult-to-clamp fixtures such as surface mounting electrical receptacles, brackets, and racks to masonry walls 

Rapid production line assembling, such as bonding together sections of reinforced plastic car bodies 

Bonding traffic buttons to highways when minimum traffic delay is important 

Cold weather construction uses such as pressure grouting, pipe joint sealing, and bridge support structure repair12 

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Silicon—Ca.rbon Thermoset. The Sycar resins of Hercules are sihcon—carbon thermosets cured through the hydrosilation of sihcon hydride and sihcon vinyl groups with a trace amount of platinum catalyst. The material is a fast-cure system (<15 min at 180°C) and shows low moisture absorption that outperforms conventional thermosets such as polyimides and epoxies. Furthermore, the Sycar material provides excellent mechanical and physical properties used in printed wiring board (PWB) laminates and encapsulants such as flow coatable or glob-top coating of chip-on-board type apphcations. 

A Review of Fast-Cure Systems for VAMAC Elastomers, Technical Bulletin E.I. DuPont de Nemours and Company, Inc., Document reference VAM020507, 2002. 

Different mixtures of anaerobic adhesives are available that offer a variety of curing times, strengths, and compatibilities. A typical cure time is 20 min for cure to begin, vibration resistance in about 1 h. Some fast cure systems will have about 20% cure in a few minutes and are almost cured in about 2 h. Some instant cure systems are ready for use within seconds. 

Provides fast cure system with ultra low formaldehyde reactants... 

Enns and Gillham, 1976) tgei T, t) from damping of a Good for fast-curing systems... 

Some of the multifunctional crosslinking monomers used in emulsion polymerization include pentaerythritol tetraacrylate and trimethylolpropane triacrylate (high boiling, low viscosity, fast cure system for vinyl acrylic latex paints) [34]. 

After base resin appUcation, the infrared eviration zones TRS/ADZ evaporate the water contained in the base resin. Then the hardener is applied in the second roller system (UMA). This technique allows one to use a very fast curing system, because the two components are mixed immediately before the film is laid down on the coated panels. A special conveyor (TRK) then moves the panels to the lamination section where a heated laminating calendar (KKL) presses the paper supplied by the unwinding unit FAA to the panels. 

Based on these results, one can expect to obtain a fast curing system containing multi-functional N-cyanourea groups. The dicyanourea compound prepared from di(P-isocyanatophenyl) methane and cyanamide melts at 85 C and has an onset curing temperature at 122 C from DSC study. This compound after being heated at 125 C, turns to a yellow rigid form in a minute. 

Unlike epoxies, which cme by an ionic polymerization mechanism, modified acrylics cure by free-radical addition. Therefore, careful proportioning of components is not required. In two-component systems, no mixing is required because the adhesive is applied to one substrate, the activator to the other, and the substrates are joined. Handling strength is rapidly achieved with this fast-curing system. 

AEM polymers, both terpolymers and copolymers, must be cured under pressure to avoid sponging. Pressures of 413.7 kPa and higher, preferably higher, are recommended for curing Vamac compounds without sponging. High viscosity compounds with fast cure systems can be molded at the lower end of the pressure range. If compression set is not a consideration, the viscosity of a terpolymer-based compound can be increased sufficiently with ionic crosslinks to be cured at atmospheric pressure [3]. 

Very fast diamine cure systems with good bin stability have been developed for AEM terpolymers. These fast, safe (scorch) cure systems have the potential to improve productivity by reducing press cure time and post-cure time, thus reducing compound cost. The basic components of the fast cure systems are shown in Table 6.18. 

Use the peroxide or peroxide/diamine fast curing system... 

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