Powder-coated metals could present a challenge when you need to bond two surfaces using adhesive. It's best to know exactly what you're dealing with before investing in a hot glue adhesive.
Powder Coating
Some people think that powder coating is a type of painting technique. This isn't the case at all. Powder coating is essentially a thin layer of plastic powder that has been sprayed onto metal and then cured under heat to form a protective skin. The most common types of plastic powders we use are thermoplastic or thermoset polymers. The hard finish is more robust than paint, and it has many benefits, including the ability to protect the metal from corrosion.
The Problem with Bonding Powder-Coated Metals
A powder-coated metal surface is a lot more difficult to bond than a painted or raw metal surface. An adhesive that may work on raw metal may not work on the powder coating. Some adhesives use a type of solvent to etch into the powder coating. This helps ensure a good bond. Some powder coatings are manufactured with a high resistance to solvents which stops the adhesive's etching mechanism from working. Choose an adhesive that is compatible with the resistance of the powder coating on your surface. TGIC polyesters are less solvent-resistant than epoxies.
All powder coatings use additives in their formulations to improve durability, control gloss, or improve UV stability. These additives can also affect the adhesive's effectiveness. A talc, wax, or slip agent additive, for example, can make it more difficult for an adhesive to bond to the surface. Always match the adhesive you choose to the surface properties and formulation of the powder coating. Adhesive manufacturers generally provide guidelines for selecting the right product according to your exact substrate conditions. Always verify the effectiveness of your adhesive by testing it on the surfaces before rolling out the solution across your plant. Here are some great options to investigate.
Hot Glue Adhesive
Infinity PUR MP75 is a general purpose, polyurethane reactive, hot melt adhesive. It is designed to bond to various substrates, including some metals. PUR MP75 is medium-fast-setting adhesive, which eliminates the need for pins and staples. This also reduces sanding and puttying after curing. The product has a UV indicator, which allows easier visibility under black lights. The Loctite H8000 Acrylic Adhesive is another high performance metal bonding adhesive. It offers a medium fixture time and has an excellent peel strength on a wide range of substrates, especially aluminium.
SuperTAC is another excellent option. This brand produces a range of hot glue adhesives to bond almost any type of substrate. If you're looking to bond metal, then SuperTAC 88 Metal and Plastic Glue Sticks are the product for you. These glue sticks offer a premium, aggressive formulation especially formulated for difficult to bond substrates. They do a great job on plastics, metals, and ceramic. SuperTAC 88 glue sticks are the perfect choice when you must deal with wide bonding needs that need aggressive tack.
Methacrylate Adhesive
ASI (or Adhesive Systems Incorporated) produces the MP 55350 Methacrylate MMA Adhesive. This is a two-part methacrylate with a non-sag viscosity. The product has a good work-life of up to 40 minutes and an open time of up to 90 minutes. MP 55350 bonds well to most metals, including aluminum, stainless, and coated metals. The adhesive is typically dispensed using a static mixer and cartridge gun.
Acrylic Adhesives
3M™ Scotch-Weld™ Low Odor Acrylic DP8805NS is a high performance, two-part acrylic adhesive. It has a lower odor than most other acrylic adhesives. This toughened acrylic offers excellent shear, peel, and impact performance. The acrylic has an exceptionally fast strength build rate and provides structural strength in minutes. The work-life is four to ten minutes, which means you will have to work faster than when using an epoxy adhesive. The product is proven to provide adhesion to many metals, even if it has a slightly oily surface. The adhesive comes in duo-pack cartridges as well as bulk containers.
Epoxy Adhesives
3M™ Scotch-Weld™ Epoxy Adhesives DP460 (off-white) is a high performance, two-part epoxy adhesive. It offers high durability and outstanding shear and peel adhesion. The adhesive maintains its hold even under the harshest environmental conditions. This product has a 60-minute work-life, which gives you plenty of time to adjust surfaces before curing takes place.
Urethane Adhesives
3M™Scotch-Weld™ Urethane Adhesives offers a range of products that provide excellent adhesion to primed, painted, or coated metal surfaces. These products are dual-component, polyurethane adhesives. They cure at room temperature or with heat and, once cured, form tough structural bonds that are impact-resistant. The adhesive primer (EC-3901) is recommended if you want to achieve maximum water and humidity resistance.
Make the Right Choice
Whether you choose a hot glue or any other type of glue, it is always important to understand the specifications and adhesive properties of the brand before you invest in using it.