Laurel and Hardy. Lewis and Clark. Some combinations just seem to go together. Aluminum panels and steel tube framing. Oak veneer and particleboard. Flexible foam and an ABS part. To readily bond these and many other combinations of high surface energy or porous materials, you have a wide selection of tape and adhesive options.
Other combinations, however, don't seem to go together as well: Oil and water, natural rubber and a polypropylene housing. These and other tough combinations like bonding EPDM rubber to a powder-coated surface, or bonding anything to oily metal without cleaning can be very challenging. But it does not have to be!
For the many product designers who consider EPDM, CR, SBR, natural rubber, and other TPV and TPE solids as hard to bond, 3M offers the easy way to bond with liquid, hot melt, and pressure sensitive adhesive choices that best meet production and end use requirements.
If you want instant World Record-type Strength adhesion over a smaller bond area, consider 3M™ Scotch-Weld™ Instant Adhesive PR100 with low viscosity for tight fitting parts. A simple pinch from a flexible container applies a precise drop or bead of cyanoacrylate, and world record power.
When 100% solids, fast bonding, and flow over a larger area are the answer 3M™ Hot Melt Adhesives offer a wide range of open times to meet your assembly needs.
For bonding EPDM, sponge rubber, or rubber sheeting to most porous surfaces with low soak-in, our SBR line of industrial adhesives can be used. This pioneering formulation dries quickly to a flexible, water resistant bond.
To illustrate the concept of surface energy, think of water on the unwaxed hood of a car. The unwaxed hood has high surface energy (HSE), and water on the hood flows into puddles. Surface energy ranges from high to low (Figures 1 & 2), and a waxed hood has low surface energy. The water beads up. Similar to water, adhesive on a high surface energy plastic, such as ABS or nylon, flows and "wets out" the surface. "Wetting out" is required to form a strong bond. Most adhesives and tapes on LSE plastics, such as polyethylene or polypropylene, however, have a tough time sticking.
Low Surface Energy - Figure 1
High Surface Energy - Figure 2
That could be a problem for engineers who want to take advantage of the lower cost of LSE plastics as compared to engineering grade plastics. But with 3M adhesives, there's no problem at all. You just need to tell us how much bond strength you need in the range from non-structural to structural. Typically, non-structural adhesives bond with less than 1,000 psi, and structural adhesives bond load-bearing parts of a product with strength of 1,000 psi and above.
If you want to bond nameplates and graphic overlays to polypropylene housings, for example, 3M offers a complete line of laminating adhesives that bond on contact after simply wiping dust off the substrates. These products can be die-cut for a precision fit, offering high shear and peel strengths, and resistance to chemicals, moisture, UV light, and high temperature. With a 200g load in shear and a half square inch of overlap, 2 mils of one of our low surface energy laminating adhesives holds at up to 444°F.
Other applications include attaching gaskets and cushions, membrane switches, underhood labels, decorative trim, instrument clusters, LCD windows, and assembly of plastic housings.
Select from 2.0 to 7.9-mil adhesive thickness to match the contact requirements of smooth, textured, or rough surfaces. Select specific products from lines of either adhesive transfer tapes or double-coated tapes. The carrier of a double-coated tape adds dimensional stability for handling ease.
At the high end of the strength spectrum, 3M™ Scotch-Weld™ Structural Adhesives are 2-part acrylics that bond LSE and HSE plastics with strength greater than the materials joined. In many assemblies, you eliminate the extra processing steps of screws and rivets, avoid the restrictions of plastic welding, and reduce surface preparation to simply wiping off dust or oil.
With a simple squeeze, the hand-held applicator simultaneously and accurately meters, mixes, and dispenses the 2-part formulation. Bond quality is consistent, and you eliminate metering guesswork, measuring time, and reduce adhesive waste.
Typical applications include assembly of a thermoplastic composite railing, bonding a polypropylene/EPDM alloy gasket into a swimming pool diverter valve, assembly of multi-layer polyethylene signage, and securing urethane rubber end caps into the bodies of polyethylene batons.
3M™ VHB™ Tapes offers the speed and convenience of a pressure sensitive adhesive with strength enough to replace rivets and screws in many applications. They bond high and low surface energy plastics to themselves and many other substrates. The white, closed cell acrylic foam carrier provides viscoelasticity to absorb impact, damp vibration, and flex with differential thermal expansion and contraction.
Used to be you had to take the time and effort of removing light oil from metal before trying to bond anything to it. Now with 3M, you've got non-structural and structural choices that bond as if the oil isn't even there, saving you time and money.
In addition to bonding LSE plastics (see above), 3M™ Laminating Adhesives bond plastic nameplates, metal rating plates, die-cut rubber or felt gaskets, foam cushions, graphic overlays and appliqués, film labels, and more to lightly oiled metal without surface preparation.
For the many designers who want thinner bond lines for thinner products using lighter weight materials, these laminating adhesives provide more strength with less adhesive on more substrates. While thin, these neat, dry adhesives conform to textures to bond and seal even against solvents and typical household cleaners. For success in electronics, appliances, medical devices, and other market applications involving exposure to heat, they can resist up to 350°F. That's enough to reliably withstand the heat from an electronics transformer.
For structural strength bonding, 3M™ Scotch-Weld™ Structural Adhesives cut through surface oil and cures at room temperature, saving the cleaning and energy cost of heat. Wherever metal meets metal in agricultural equipment, appliances, elevator panels, construction equipment, trailers, and millions of other products, toughened epoxies can increase bond line durability for long-term rugged use. Overlap shear strength of 4,400 psi and an average T-peel of 21 piw combine to provide one of the most powerful adhesives available.
Powder coating is applied electrostatically to metal, and heat-cured to form a protective and decorative layer that's tougher than conventional liquid paint. Metals such as aluminum or stainless steel are high surface energy (Figure 2 above), but once the metal is powder coated, you will be bonding to a low surface energy "skin". You have many choices in pressure sensitive adhesives, depending on how much holding power you want. If you have any questions about selecting the right 3M product for your application, a 3M technical specialist is always available to chat. For higher holding power in static and dynamic loads, 3M™ VHB™ Tapes often replace mechanical fasteners in applications such as bonding powder coated metal stiffeners in office desks and filing cabinets.
Metal Surfaces (High Surface Energy) - Figure 3
Silicone repels and makes a great gasket for keeping out water and solvents, even in very high heat environments. The problem for product and manufacturing engineers, however, is that silicone also tends to repel adhesive unless primed. At least, that's how it used to be.
3M silicone adhesive transfer tapes and double coated tapes bond silicone rubbers and foams to themselves and to other substrates on contact without priming. High shear strength, good peel strength, and high solvent resistance combine for success in such applications as gasketing, flexible keypad assembly, Buzz/Squeak/Rattle control, and splicing silicone liners. These silicone adhesive tapes can resists up to 500° F for high heat applications such as brake shim bonding.
Many tapes can feature a polyester liner to reduce liner waste by 50%, and save the time and cost of second liner removal and disposal. Stable liner release with low gms/in over time and a 12-month shelf life extends usability for a better return on your tape investment.
3M offers a wide range of innovative adhesives that can be selected for optimal bond area and anticipated loadings in joint designs.