As electric vehicle sales increase and plastic continues to displace steel and aluminum in vehicle manufacturing, multimaterial products with electromagnetic shielding and flame retardancy from a mix of plastics with metal alloys are expected to become more popular.
Once the total cost of ownership for EVs becomes lower than that of internal combustion-engine vehicles, the market will expand and fuel material developments even further, Todd Glogovsky, executive vice president of sales and technology at Asahi Kasei Plastics North America Inc., told Plastics News.
"The cost to produce the batteries is decreasing every year — something like 20 percent a year," Glogovsky said, adding that consumer cost will ultimately drive the market.
"It's exciting," he added. "Injection molding is a process that the auto industry has a lot of history in. Materials that are capable in that process that meet the performance requirements are going to be evaluated," like polyphenylene ether blends, polystyrene and nylon.
"These combinations bring different levels of performance but all can be flame retardant," he said. "Performance always has to come first. ... Having multiple options is going to be a benefit.
"Polypropylene from a weight standpoint is probably one of the lower-density materials; it is not affected by moisture," Glogovsky said. "Polyphenylene ether combines both very stable, tight dimensions and high-temperature performance with no moisture issues, and it's easily flame retardant."
Asahi Kasei is also looking at thermoforming material grades for larger parts, he said.
"You're looking at parts that could be anywhere from 15-20 pounds," Glogovsky said. "Some of these bases are so big, thermoforming becomes an option for small production runs."
The scope of applications for those materials is still being defined, he said, as the market is still developing.
Flammability requirements change design, while electrical properties also become more important in EV development, Glogovsky said.
Top and bottom battery covers have to be weight- and flammability-managed, while the bottom tray is typically flame retardant, he said.
"The top cover is still being discussed," Glogovsky added. "Most of the temperature requirements are for the cooling systems, coolant tubes or cooling water.
"As this market expands, productivity will become more important, so [will] cycle times," he said, and supply chain disruptions will become an even bigger challenge.
Many raw materials needed for EV applications are processed outside of the U.S. in places like Australia and China.
"Even though the polymers themselves and the glass reinforces are local, a lot of these flame retardant [minerals] are produced offshore," Glogovsky said. "The global supply chain will become more critical with the EV market."
Asahi Kasei has had to change its inventory levels, carrying more safety stock than normal, he said. Congestion at ports has increased lead time from four to eight weeks.
"The challenge is transporting [materials] and getting ahold of sea containers," Glogovsky said. "We also see delays with loading. … All these links in the supply chain have been a challenge. The end result is you have to carry more inventory, and how do you do that when there are issues bringing product in?"
Bumps in the materials supply chain will remain a dominant discussion for all plastics suppliers, as costs for everything — from gasoline to steel and polymers — continue to rise, he said.
"[This] seems to be a continuous event putting a lot of stress on everyone. ... It's really a challenging period."