Heat-cured adhesives

Resolution Performance Products, Starting Formulation 4018, High Strength Room Temperature or Heat Cure Adhesive, Houston, Tx, August 2003. 

Heat cured adhesive systems are generally more resistant than room temperature cured systems. 

Room temperature curing, two-part epoxy adhesives are usually considered to have a lower level of outdoor performance than the heat cured adhesives. Their performance, however, can be improved by heat treatment following the room temperature cure. 

Heat curing adhesives are less sensitive to surface preparation than room temperature curing adhesives. 

Adhesive tapes are also suitable as fixing aids for the manufacturing of bonded joints to secure adherends against moving (in the case of heat-curing adhesives, however, applicable only to a limited extent). 

When bonding pure zinc, its low recrystallization temperature (10-80 °C, depending on the metallurgical condition) has to be taken into account, which limits the application of heat-curing adhesives. 

Heat-curing adhesive Adhesive requiring a predetermined temperature-time profile for curing. 

Type of adhesive Adhesives based on different adhesive raw materials with special processing properties (e.g., hot-melt adhesives, pressure-sensitive adhesives), different purposes of use (e.g., wallpaper paste, wood glue), processing temperatures (e.g., cold glue, heat-curing adhesives), availabilities (e.g., adhesive films, solvent-based adhesive). 

Acrylate adhesives differ from other polymer types in their ability to be cured rapidly by exposure to UV and/or visible light. Their main advantage over heat-curing adhesives is in bonding heat-sensitive electronic devices in 5-30 seconds at room... 

Heat-cured adhesives. Heat curing by convection in box ovens is the most widely used and simplestmethod for curing adhesives. Heat is applied until a temperature is reached at which polymerization occurs and continues until the polymerization is complete. Time-temperature curing schedules are developed for each adhesive for which optimum properties are achieved. F or each of their adhesives, suppliers provide several cure schedules that are considered equivalent relative to final properties. The user may also develop... 

Composite materials, like adhesives, are permeable to water. Moisture can therefore diffuse to the adherend/adhesive interface, which is a problem more in initial joint fabrication when a heat-cured adhesive is employed than when the joint is in service. Thus the moisture content of the composite at the time of joining should be low (say 1%) or else moisture may be drawn to the interface by... 

However, often the temperature required to cure the adhesive will adversely affect heat-sensitive plastic parts. Also, heat-curing adhesives are generally more rigid than those that cure at room temperature, and the resulting modulus is too high for many plasticbonding applications. As a result, most adhesives recommended for bonding plastic substrates cure at room temperature. 

In a review of previous work, DeLollis concluded that the nitrile-phenolic is the most durable adhesive, surviving all environmental exposures. The nylon-epoxy adhesive performed well on exposure to medium-humidity environments, but was susceptible to high humidities. The nitrile-epoxies showed good resistance to most outdoor exposures except the seacoast environment, where bonds failed after four years. Epoxy/polyamide bonds gave good results after four years exposure to an industrial environment and joints exposed to a tropical climate had retained about 33% of their initial strength after three years. This performance should be compared with that of some heat-cured adhesives, for which the bonds are completely degraded by tropical exposure. 

It may be necessary to provide means for cooling heat-cured adhesives during storage and even extending temperature control as far as the factory floor. These products can cure in the pail when subjected to storage temperatures that are too high. 

Durability Performance with Different Surface Pretreatments Using a Heat-Curing Adhesive... 

Heating and other curing equipment (ovens, lamps, UV sources). For some heat-cured adhesives, their cure temperature can be chosen to match another stage in the manufacturing process, e.g. adhesives which cure during the paint-stoving operation of automobile manufacture. 

Manufacturers Comments Black, heat curing adhesive with excellent resistance to thermal shock, chemicals and water. High thermal stability. 15% min. total solids - Roll coat, spray and brush grade. 

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