Often the strongest glue for plastic may not be the best adhesive for plastic. There are a variety of factors to consider when choosing the best plastic glue. Obviously, bond strength is at the top.
For most plastic bonding applications cyanoacrylate adhesives, UV curable adhesives, MMAs, as well as some epoxy and structural adhesives are options. The large variety of adhesives available can make selecting the best adhesive for plastic seem difficult.
To determine which adhesive for plastic will have the highest bond strength, it is often necessary to know the exact nature of the plastic. The type of plastic as well as the surface condition of that plastic and what the bond must resist.
Permabond cyanoacrylate adhesive bonds most ABS (Acrylonitrile butadiene styrene), PMMA (acrylic), Nylon, Phenolic, Polyamide, Polycarbonate, PVC (both rigid and flexible). For cyanoacrylate adhesive to show good bond strength on polyethylene or polypropylene use Permabond POP primer.
All Permabond plastic bonding UV curable adhesives bond well to most ABS (Acrylonitrile butadiene styrene), Nylon, Phenolic, Polyamide, Polycarbonate, PVC (both rigid and flexible). Special plastic bonding UV curable adhesives are available for acrylic.
One part epoxy adhesives are generally viable because the minimum cure temperature of the epoxy tends to be higher than the maximum temperature resistance of many plastics. Higher temperature resistant plastics such as PEEK and PBT can be bonded with special heat cure epoxy.
Two part epoxy adhesives can be used to bond certain plastics. Special grades of plastic bonding epoxy are available from Permabond where high strength performance is required. Modified epoxy adhesives are two part epoxy adhesives that provide much higher flexibility than traditional two part epoxy adhesives.
Structural acrylics will also bond most plastics. Many types are available including surface activated, bead on bead, and two component. MMAs (methyl methacrylate adhesives) are an effective way of bonding plastic substrates and offer impressive adhesion strength – often substrates break before the adhesive bond is broken.
Specialty grade acrylics such as Permabond TA4610 are available to bond polypropylene, polyethylene, and other polyolefins with no need for a primer.
Many applications have more than simply bond strength as a requirement. Some of the other factors most engineers must address include appearance, application and cure process, chemical resistance, and temperature resistance.
UV plastic adhesives can provide invisible bonds, which are often desirable on clear plastics. Dual cure grades are available for colored plastics. Cyanoacrylates also provide clear bonds. For best results on dark colored plastics when using a cyanoacrylate adhesive, choose a low odor, non-blooming grade.
Cyanoacrylates (instant adhesives) are desirable due to the near instantaneous fixture strength. However, in some applications, more time is needed to apply or accurately align components. UV adhesives provide that but note that many plastic bonding UV curable adhesives can also cure with visible light (normal room lighting) so if considerable time is needed for alignment or dispensing, be sure to shield the parts from light.
Adhesive Type Resistance to Non-Polar Solvents
Examples of Non-Polar solvents include motor oil, gasoline, and toluene.
Adhesive Type Resistance to Polar Solvents
Examples of polar solvents include water, ethylene glycol, isopropyl alcohol, and acetone.
Adhesive Type Standard Heat Resistant Adhesive High Heat Resistant Adhesive
If your plastic isn’t listed, please contact Permabond for a recommendation.