Debunking Myths About Bonding Tapes for Transportation

Myth #1: Screws, rivets, and mechanical fasteners are stronger than tapes.

Fact: Tapes can provide a significant advantage over traditional mechanical fasteners. This is why tapes are preferred in a variety of automotive applications, including in commercial and utility segments such as within trucks, buses, and trailers. Tapes are often the go-to materials that are used to secure roof and body side panels, exterior trims, emblems, as well as instrumentation.

Key advantages of using tapes are reduced time and labor for application, fewer surface irregularities, fewer seams, a cleaner appearance, ease of installation, proper adhesion, and long-term reliability. Tapes also can reduce and absorb the impact of vibration and noise, provide waterproofing, and eliminate potential sources of corrosion and cracking.

An added benefit is that Norbond Tapes, such as A7700 (black), A7600 (grey) or A7450 (white) provide discreet color options for seamless integration and desired aesthetics. They eliminate surface deformation, exposed fasteners and the need for cosmetic caps.

Based on the above-mentioned considerations, it is clear that mechanical fasteners are the less-preferred choice because using them involves more parts, greater assembly times, and increased labor and tooling costs. Additionally, unlike tapes, mechanical fasteners cannot make assemblies water-tight, which often leads to premature rusting or failure of the fasteners and connecting parts. Screws, clips, or rivets can also compromise aesthetic appearance by increasing forces and stresses near where the fastener is applied.

Myth #2: All tapes are the same.

Fact: Although the concept of “stickiness” seems like a basic metric, the performance of a bonding tape is dependent on several factors such as peel, tensile, and shear adhesion. This is very important to remember when making material selections.

To test for peel adhesion, the tape is pulled away from a surface at a specific angle, per ASTM D330, which is the most common industry test. This test measures the bond strength to a singular surface.

However, this test only tells part of the story. To better understand how a tape will endure forces like vibrations, motion, or shifting loads, shear adhesion and tensile strength are important considerations. These are measured under very different test conditions (ASTM D1002 and ASTM D897, respectively) and better reflect how a tape will respond to real-world stresses, sliding, or pulling forces.

Myth #3: Foam carrier or film carrier: It makes no difference.

Fact: In general, the choice of carrier materials affects the tape’s in-plane tensile and tear strength and can enable conformability of the tape to rough or irregular surfaces. Carrier materials can be either foams or films.

Within transportation applications, tapes are typically two-sided, and contain a substrate or carrier, which forms the body or core of the tape. Tapes have adhesives on either side of the substrate that bond the two parts, or adherends, together. In these applications, foam tapes are advantageous to film tapes. Foam tapes are highly conformable and provide air- and water-tight seals. Foam tapes may also distribute loads over larger surface areas to reduce stress and they also exhibit viscoelasticity, which is the ability of the tape to flow or relax when subjected to high stresses or temperatures, thereby reducing stress over time. In contrast, film tapes may not be suitable for transportation applications, since they concentrate loads at the immediate contact point between the substrate and the adhesive layer, causing high stresses that may lead to failure.

Foam carriers can be polyethylene, polyurethane or acrylic. Polyethylene carriers are generally used for basic mounting applications and offer good conformability to irregular surfaces and static shear resistance. Polyurethane carriers consist of highly engineered closed-cell foams that contain flexible cross-links that allow for high strength, resilience and some viscoelastic properties. Acrylic foams are viscoelastic and provide high elongation and excellent stress relaxation properties.

Myth #4 Silicone adhesives are the best choice for transportation applications.

Fact: Adhesives can be heat-activated or pressure-sensitive acrylic, rubber or silicone. Silicone adhesives may not be well-suited for attachment applications in transportation. Although they have good high-temperature adhesion, they may lack stiffness at room- and sub-ambient temperatures. Furthermore, they may require primers or other surface treatments to enable them to adhere to certain materials.

Rubber adhesives may also not be the most appropriate choice for transportation applications since they may age poorly, have low resistance to ultraviolet radiation, and have lower cohesive strength compared to acrylic or silicone adhesives.

Acrylic adhesives are the best choice for transportation applications since they have good adhesion to a wide range of materials, good aging and resistance to ultraviolet radiation, and an ability to operate over a wider temperature range, compared to silicone or rubber adhesives.

Myth #5: Tapes won’t hold up in extreme weather conditions or under severe operational conditions vehicles are exposed to.

Fact: Norbond Tapes are specially engineered to maintain their form, fit, and function over the lifetime of a vehicle. Since commercial vehicles are driven over longer distances and used by more operators over longer periods, they are especially vulnerable to severe operational and environmental conditions. With proven success over more than 50 years, our OEM-approved automotive products have been designed to achieve the longevity and durability performance essential to manufacturers in this market.

Norbond Tapes can generally maintain bond integrity from -30ᵒF (down to -40ᵒF for select products) to 200ᵒF, with the ability to also withstand short-term heat spikes (<5 min) up to 300ᵒF. From sub-zero temperatures to sweltering heat, these tapes are designed to withstand cycles of thermal expansion and contraction without becoming brittle or soft.

Additionally, the close-cell foam core of our bonding tapes helps to resist water, moisture, wind, and other environmental stressors, making them ideal for both interior and exterior applications.

Generally, Norbond Products are designed to last.

Long-term static shear tests have demonstrated that these products have the ability to withstand sustained mechanical loads and resist creep over time, making them ideal for applications such as skin bonding, trim attachment, and roof bows. They are proven to withstand dynamic bending, tensile, stretching, shock and vibration loads as the vehicle traverses over rough surfaces or if exposed to high dynamic pressure and wind by operation at high speeds. Additionally, these tapes maintain dimensional stability and maintain clean interfaces between assemblies that last for the lifetime of the vehicle when exposed to air, ultraviolet radiation, salt spray and other adverse conditions.

Now that we’ve debunked some common myths and misconceptions, it is clear why Norbond Tapes are the premier choice for transportation applications.

Let’s explore some options that combine polyurethane or acrylic foam cores with high-performance pressure-sensitive adhesives to meet the needs of modern vehicle construction across trailers, busses, trucks and specialty equipment.

1. Norbond V2800 Series Bonding Tapes combine a black polyurethane foam substrate with a high-performance, pressure-sensitive acrylic adhesive on both sides that provides a strong, long-lasting bond. The V2800 Series Tape is specially designed to reduce the distribution of stress at pressure points, thereby minimizing distortion. It has high tensile/shear adhesion and is a good choice for shorter length components (less than 3 feet). Using a conformable, closed-cell polyurethane foam, it has excellent environmental resistance, and prevents corrosion of dissimilar materials by eliminating the contact between them. Norbond V2800 is available in a variety of standard thicknesses from (0.030 in to 0.120 in) and in widths from 6 mm (0.25 in) up to 1,422 mm (56 in). 
   
   V2800 is durable in all weather conditions and provides resistance against UV light, extreme temperatures, fungi, oxidation and ozone. Because of this, Norbond V2800 is an ideal choice for severe exterior bonding applications such as, emblems and ornamentation, trailer roof bows, panel stiffeners, and body side moldings.
    
2. Norbond A7600/ A7700 Series are high-performance, double-sided acrylic foam bonding tapes with outstanding viscoelastic and adhesion properties. A7600 features a gray acrylic foam core that allows for the product to hide in the sight line, while A7700 features a black acrylic foam core. These products are well-suited for high- and medium-surface energy materials, such as metals or ABS plastics, and offer ideal bonding performance for many interior and exterior industrial applications.
   
   Formulated for durable, long-lasting adhesion, A7600 and A7700 exceed industry standards for shear strength and bonding to high surface energy substrates, even at elevated temperatures. They have high elongation/expansion capability, and quick adhesion build (80% of ultimate adhesion at 20 minutes). They have excellent performance in peel, tensile and dynamic shear adhesion, and provide resistance and absorption of dynamic loads. They are available at a standard thickness of 1.1 mm (.043 in), and various widths from 6 mm (0.25 in) up to 800 mm (31.5 in). These products are best suited for interior and exterior trailer skin bonding, and general bonding applications.
    
3. Norbond A7450 (white) and A7350 (gray) provide a robust solution in applications that are more demanding. These acrylic foam tapes offer elevated peel and tensile adhesion, making them ideal for bonding where stresses are increased due to welds, thicker metals, or heavy-duty mechanical loads. With excellent environmental and thermal resistance, these tapes are trusted in structural joints, where reliability under shifting conditions is crucial.

Benefits such as quick stick adhesion, NVH reduction, improved aesthetics, durability and high-performance, when exposed to environmental and operational extremes, make Norbond Tapes ideal for transportation assemblies. These tapes balance mechanical durability, surface compatibility, visual requirements, and environmental resistance. For more information on the variety of Saint-Gobain Tapes for numerous transportation applications, explore our solutions for the automotive and transportation industry or contact us today.