Traditionally, solvent-borne adhesives have been the go-to solution for certain automotive interior applications. These versatile adhesives have enabled fast production speeds and efficient automotive door and instrument panel assembly in particular.
However, new government regulations are causing automotive manufacturers to consider other adhesive options instead. Let’s take a closer look at why this is the case.
Why are Automotive Manufacturers Considering Other Adhesive Options for Door and Instrument Panel Assembly?
While solvent-borne adhesives will remain a viable option for various applications in other markets, they do contain volatile organic compounds (VOCs). VOCs are organic chemicals that evaporate into the air and can cause adverse environmental and health effects. In order to minimize their usage, the government has issued federal, state and local ordinances and permits.
These put a cap on the amount of VOCs a company is able to produce. As a result, automotive manufacturers that use solvent-borne adhesives will experience limited production and revenue capabilities per site.
To avoid this, they are turning to other options, such as water-borne adhesives.
Why Use Water-Borne Adhesives for Door and Instrument Panel Assembly?
Water-borne adhesives can vent to air. This means they do not require special permitting or handling costs like solvent-borne adhesives, which keeps operational costs lower and production capabilities higher.
Water-borne adhesives also have a near-zero VOC percentage. They are safer to handle than solvent-borne adhesives.
Furthermore, manufacturers that currently have solvent-borne adhesive equipment are able to use it for water-borne adhesives with only slight adjustments. Like solvent-borne adhesives, water-borne adhesives are able to be spray and roll coated. As a result, it makes for a simple transition from solvent-borne to water-borne adhesives.
How are Water-Borne Adhesives Able to Keep Up with New Materials and Production Speed Demands?
- New Materials Used in Door and Instrument Panel Assembly
Historically, plastics such as polycarbonates and ABS have been used in door and instrument panel assembly. However, as automotive manufacturers respond to demands to produce lighter weight, more fuel-efficient vehicles, polyolefins are replacing these plastics. Polyolefins:
- Offer a great deal of rigidity and strength at a lower basis weight than many other plastics
- Are more cost effective to produce than traditional plastics
While solvent-borne adhesives exhibit excellent adhesion to polyolefins and unprimed polypropylene in particular, this is not the case for many other adhesive options. Yet with proper formulation, water-borne adhesives can adhere to new materials, including polyolefins and unprimed polyproplylene.
- Fast Production Line Speeds
Solvent-borne adhesives are comprised of only 20-30% solids. This means that 70-80% of the adhesive is comprised of solvents, which evaporate into the air. Their quick evaporation has enabled fast production line speeds.
While water evaporates slower than solvents, water-borne adhesives are 40-70% solids, depending on the application. This means that there is less evaporation with water-borne adhesives than with solvent-borne adhesives, ensuring fast production line speeds are still met.
Smart Innovation at Work
However, it’s important to note that even water-borne adhesives are not without their environmental and health concerns. Historically, these one and two-part urethane products have contained isocyanates.
Bostik is currently working on a water-borne adhesive product that will not use urethanes in its formulation. As a result, this product will be a smart, safe option for automotive door and instrument panel assembly. For more information on Bostik’s innovative capabilities, call 800-7-BOSTIK.