Automotive Adhesives and Sealants
The way people travel in vehicles has evolved tremendously over the last century. From plush interiors to high-speed powertrains, cars have become increasingly advanced.
But the most significant advancement is a shift to lighter materials. This has required novel assembly techniques that utilize structural adhesives instead of traditional steel fasteners.
Urethanes
The rapid transition to lightweight vehicles that maximize speed and power requires innovative assembly techniques. Structural adhesives, which offer outstanding bonding qualities to composite materials and metals where welding isn’t suitable, are increasingly being used by automotive professionals to keep vehicle weight to a minimum. They also allow cars to be designed with aesthetically pleasing shapes and reduce the risk of loose parts during driving.
Urethanes are available in a wide range of formulations to suit different applications. Some are supplied in side-by-side, fixed-ratio cartridges and require dynamic mixing to be dispensed; others can be pumped from pre-mixed containers or with metering equipment. They can be rigid or elastic and cure at room temperature or with heat.
Unlike some other varieties of auto adhesives and sealants, urethanes do not contain isocyanates, which can cause a chemical reaction that results in bubbling during the curing process. This feature makes urethanes ideal for bonding glass to automobile components such as windshields, since it eliminates the need for mechanical fasteners and reduces vehicle weight.
In addition to bonding plastics to metallic substrates, urethanes are ideal for sealing joints and seams in the chassis of automobiles, where they provide strength and resilience. They are also excellent for potting electronic components and sealing the edges of filters. As a result, they are frequently used for attaching interior car panels, such as dashboards and instrument panels.
Epoxies
With their innate ability to resist a relentless weight and withstand chemical or physical influences, epoxy adhesives are a natural fit for automotive bonding, coating, sealing, and encapsulation. Formulations that are fast curing, flame retardant, high temperature resistant, and cryogenically serviceable have further fuelled their penetration into the industry.
Structural adhesives help automakers meet the challenge of reducing vehicle weight, automotive adhesives and sealants while adding design freedom and improving structural rigidity, component performance, and safety. They are ideal for bonded BIW construction – especially in the hem bonding of hoods, trunks and doors – and are designed to work with both aluminum and structural steel and bond dissimilar substrates. Some also have excellent impact resistance and low outgassing.
Moreover, many are compatible with paint, draw and lube oils. And because they cure quickly – often in standard automotive bake cycles and e-coat ovens – they can simplify manufacturing processes.
Aside from their structural applications, automotive epoxy adhesives are also popular in finishing and a wide range of assembly tasks. They can repair vinyl tears in upholstery; seal windshields and headlights; insulate electrical wiring; and stick emblems and side molding strips in place. They are also a key ingredient in creating custom finishes for body, chassis and powertrain components. And finally, they can provide a more lightweight method for joining plastic and composite parts, resulting in a lighter vehicle, better stress distribution, and improved NVH.
Water-Based Sealants
Among the many automotive adhesives and sealants used are those that form strong, water-resistant bonds between surfaces. These include the silane/siloxane and fluoropolymer families of materials. Silanols are better at repelling water, while fluoropolymers excel in repelling automotive adhesives and sealants oil. These sealants come in both solvent and water based versions with different quality levels and price points.
Another use for automotive adhesives and sealants is to prevent leaks in medium and heavy commercial vehicles that are used in utility operations such as trash collection, emergency services, etc. These vehicles are often exposed to harsh environments, including ice, snow, and rain, which require high-performance automotive adhesives and sealants that have superior durability, even after exposure to extreme temperatures.
Adhesives and sealants are used throughout the vehicle to secure parts, provide insulation, and create functional components. They are applied to substrates such as glass, ceramic, metals, plastics and a variety of composite materials. They also withstand environmental conditions such as temperature, stress (compressive or tensile), chemical exposure and impact. Additionally, they may need to perform special functions such as fire resistance, sound insulation, UV stability or display a particular surface appearance. Automotive adhesives and sealants are available in a variety of formulations, including solvent-borne, hot-melt and reactive, to address these diverse needs.
Other Types
Several other types of automotive adhesives and sealants exist that cater to special needs of the automotive industry. For example, methyl methacrylate (MMA) adhesives are extremely strong and durable, which makes them ideal for work on vehicles. They have the ability to bond with a wide range of materials and are safe around electrical parts. They come in one and two-part varieties and are popular for use on rust, scratches, dents, and holes.
MMAs also offer the advantage of rapid curing, which reduces manufacturing downtime. Unlike epoxies, which gain strength gradually as they cure, these adhesives can be applied and fixtured right away. This can significantly cut down on the time required to complete vehicle assembly and repair.
The global automotive adhesives and sealants market is growing at a healthy rate, primarily due to surging demand for lightweight vehicles that can save on fuel consumption. Furthermore, stringent safety standards and regulations are also driving the growth of this market.
Adhesives are widely used for bonding a variety of components in cars and trucks, including door skins, armrests, headliners, consoles, and load floors. They also help to enhance passenger comfort and add plushness to interiors by laminating leather, plastic, and vinyl surfaces. Moreover, they can be used for sealing and repairing cracks and gaps in the chassis. They can even help in absorbing vibrations from the engine and road, which is important for driver safety.
