Solvent-based acrylic adhesives are considered the performance adhesives in the PSA industry.
Acrylic adhesives are naturally UV stable and suitable for long term applications due to being resistant to oxidation. Acrylic adhesives are known to have a great bond to a variety of materials, including LSE substrates with proper formulation. In other instances, acrylics can be formulated to have very high cohesive strength and very low tack and adhesion for delicate applications. The temperature range on an acrylic adhesive can vary greatly depending on the monomers selected and additives in the formulation, however due to the flow and lack of oxidation, acrylics are suitable for a very wide temperature range. Acrylics can be designed to work at much higher temperatures than synthetic rubber-based adhesives. Solvent-based acrylic PSAs are employed in many long term, high performance applications where the product simply needs to stick. One of NECAL’s most prominent strengths is coating solvent-based acrylic adhesives at 4-5 mils thick with a good, bubble free condition.
The Rubber based adhesives that NECAL formulates and coats are based on synthetic, elastomeric rubbers, and are excellent, general purpose materials. These adhesives can be formulated to bond to a broad range of materials, including Low Surface Energy (LSE) materials such as polyethylene materials. These adhesives are inherently resistant to shear forces. The NECAL Rubber based adhesives can be formulated to modify the application and operation temperature range, with a general operational temperature around 0°C to 100°C. These synthetic rubbers do not have inherent UV stability, and will be more susceptible to color changes and breakdown in UV light. These rubber-based adhesives are also susceptible to degradation by plasticizers, such as those typically found in monomeric vinyl films.
DRY FILM HEAT-ACTIVATED
NECAL also produces a family of Dry Film Heat-Activated Adhesives. These thermoplastic adhesives are tack-free at room and slightly elevated temperatures, then bond substrates when at higher temperatures. This allows for materials to be laminated with the Heat Activated Adhesive and then reactivated with heat to bond a second substrate. Between the initial and final laminations, the Heat Activated Adhesive will not stick to any other material, improving process efficiencies as the adhesive will only bond when activated with high heat.
Water-based acrylics share many of the same properties as solvent-based acrylics. The properties such as wide temperature range, UV and thermal stability spill over to the water-based acrylics. Another positive is that the water-based acrylics do not have the additional solvent cost and thus are typically at costs below solvent-based acrylic and rubber adhesives. Water-based acrylics do need to be suspended in water via surfactants and other additives, where these additives do reduce the performance of the water-based adhesives. Typically, water-based adhesives will have lower shear resistance, adhesion, and tack and temperature range compared to the solvent-based acrylics. These products can be formulated to improve properties such as LSE substrate adhesion, reduced tack, increased cohesive strength. Water-based acrylics are not normally coated as thick as the solvent based, but strides have been made to increase the thicknesses a coater can obtain. Overall, water-based acrylics are a very good option when low cost, UV and oxidation resistance, and a wide operational temperature range is required, without the need of a thick adhesive.
When selecting an adhesive chemistry NECAL will work with clients to identify the application parameters and critical-to-quality characteristics with the following questions:
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