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Self-driving cars are coming. Chemical makers are racing to keep up

Automakers will need cutting-edge chemicals, coatings, and materials to deliver on the promise of autonomous vehicles

by Craig Bettenhausen
October 25, 2020 | APPEARED IN VOLUME 98, ISSUE 41

 

09841-cover-nuro.jpg
Credit: Nuro
Nuro's driverless R2 vehicle is in testing in California. Its predecessor, the R1 (shown), delivered groceries in Scottsdale, Arizona.

In brief

A convergence of new technologies will finally bring self-driving cars to the mass market in the next decade. Experts think the robot vehicles will start by delivering packages within limited areas. Then, bit by bit, they’ll make it out onto the open road with humans inside. This future hinges on sensors that let computers see the road. The sensors need to become more robust and sensitive while coming down in cost. An increasingly electric fleet will also demand lighter-weight materials and designs alongside improvements in cooling and lubrication. It’s a big set of changes that will challenge the chemical industry—and create opportunities.

Talk with businesspeople and policy makers involved in mobility, and it becomes clear that self-driving cars are not a matter of if, but when. These vehicles will be front and center in a future where cars are connected, autonomous, shared, and electric—what advocates call CASE. Any one of those features would upend the auto industry, and they’re all coming at more or less the same time, perhaps as soon as the end of the decade.

Then again, we’ve been talking about self-driving, electric cars for a long time. What’s the hold up? “What’s been happening over the past couple of years has been the growing realization that this is actually a much more difficult problem than everybody thought,” says Sam Abuelsamid, a principal research analyst at Guidehouse Insights. “The technology is simply not mature enough. It’s making progress, but it’s not as good as human drivers yet.”

And well before the Ubers and Lyfts of the world replace their controversial gig workers with artificial intelligence—and before we give up our personal vehicles—autonomous package-delivery vehicles will hit the roads, Abuelsamid predicts. That’s because package routes can stay on slow, calm thoroughfares and minimize challenging tasks such as left turns. “Packages don’t care if it takes an extra 5 or 10 min to get there,” he says.

“If you don’t have to worry about carrying passengers . . . that actually lowers the bar for deploying these vehicles,” Abuelsamid adds. “People expect to be able to summon a ride and go from any arbitrary point to any other arbitrary point in the quickest time possible.” Insurance companies and government regulators are also less worried when there isn’t a human life in the car.

Indeed, a company called Nuro has self-driving delivery vehicles on the road now. The firm started with a grocery-delivery pilot program in Scottsdale, Arizona, in 2018. At first, it used self-driving Toyota Priuses with a backup driver. In December of that year, the driverless, golf-cart-sized R1 joined the pilot. R1s, and their successor, R2s have four gull-wing doors that open toward the sidewalk to reveal configurable parcel compartments.

Nuro has since moved on to a larger pilot in Houston, where automated Priuses are delivering groceries from Kroger in six zip codes and prescriptions from CVS in three zip codes. The pilot will expand to include Domino’s Pizza and Walmart soon, the firm says. R2s are distributing medical supplies in a COVID-19 field hospital in Sacramento, California.

Still, self-driving passenger vehicles are what most capture the public imagination. Several car companies and technology firms are testing self-driving taxis, though most have a staffer sitting in the driver’s seat. Tesla, Nissan, and others have varying levels of automation that drivers can turn on under certain conditions.

The management consulting firm McKinsey & Company predicts that robotaxis could handle 9% of all miles traveled in the US by 2030 and as much as half by 2040. “It is probably, in our view, the next big thing,” McKinsey partner Philipp Kampshoff says in a 2017 video on self-driving cars.

In a report released earlier this month, the firm says electrification and interiors present the strongest growth opportunities for the chemical industry. McKinsey also predicts declines in materials and chemicals related to engines, such as high-temperature plastics and rubbers, lubricants, and fuel additives.

This is actually a much more difficult problem than everybody thought.
Sam Abuelsamid, principal research analyst, Guidehouse Insights

Whether it’s packages or people moving, getting to this point has taken a lot of science and engineering.

High-tech computers and batteries get the attention, but the chemical industry is quietly bringing solutions to many of the less-obvious problems of autonomous driving. The demands of computer vision require a lot of chemistry support. A design shift in car interiors that emphasizes usable space will create a need for structural materials that are strong, lightweight, and attractive to the eye and touch. And the electric motors that are expected to move most self-driving cars need different fluids than internal combustion engines.

It’s a boom time for R&D. Most major carmakers are working on CASE vehicles, and new firms like Nuro that lack anchors in internal combustion are offering serious competition. For the most part, each one is working in isolation, developing its own systems with their own challenges. That dynamic means companies’ suppliers, including specialty chemical firms, need to customize offerings for each client. And they need to be ready to iterate along with a quickly evolving field.

09841-cover-waymo.jpg
Credit: Waymo
Waymo opened its fully driverless taxi service to the public in Phoenix earlier this month.

Paul Perrone says robotic driving systems are ready to do real, meaningful work now. His firm, Perrone Robotics, specializes in bounded-zone self-driving vehicles, such as its pilot shuttle service around the Fort Carson US Army base in Colorado. He expects autonomous driving to penetrate deep into the mobility market in the next few years. “In just the subset we operate in, the opportunity is enormous,” Perrone says.

He envisions mobile autonomous robots in widespread service on roads, on sidewalks, in the air, and in the water. However, “I think there are a lot of titanic failures to come,” Perrone warns. He expects some high-profile firms to run out of money before they have a product ready to deploy at scale.

Perrone likens the state of vehicle autonomy to the dawn of powered, heavier-than-air aviation. A number of groups were working on bold, bioinspired flying machines. The first invention in the air, though, was based on established technology from kites and boats. “The Wright brothers succeeded where others failed,” he says, “by building something they understood how to control.”

Aiding the sensors

To drive, a computer needs to see. In March 2018 in Arizona, a Volvo in a self-driving test by Uber struck and killed Elaine Herzberg, who was walking her bicycle across a road at night. Two years earlier, a Tesla car in self-driving mode killed its owner, Joshua Brown, when it failed to recognize the white side of a tractor trailer against a bright daytime sky. In both cases, the computer’s vision systems didn’t recognize the hazard in time for the artificial intelligence to apply the brakes. The human copilots didn’t either.

Levels of autonomy

Self-driving vehicles are ranked by how much control the computer has over driving.

Level 0: No automation.

Level 1: Cruise control and parking-assistant systems help the driver control the vehicle.

Level 2: Partial automation can control speed and steering under certain conditions.

Level 3: Conditional automation drives the car most of the time, but the human must be ready to take over at any moment.

Level 4: High automation drives the car almost all the time, but the human can take over if desired.

Level 5: Full automation; the car can handle all driving conditions. Humans are only passengers or absent entirely.

The autonomous cars currently being tested generally watch the road in three ways. They build a detailed depth map by scanning the area with near-infrared (NIR) lasers and measuring how they reflect, a technology called laser imaging, detection, and ranging, or lidar. Overlaid on that map is information from radar, which uses radio or microwave radiation to detect objects and determine their speed and direction. Cameras use visible light to add detail and identify objects.

All three imaging methods share a prosaic need: the sensors need to stay reasonably clean, though radar is less touchy on that point. Two ways to maintain clean sensors are nonstick and self-cleaning coatings. And for both, manufacturers can draw on existing expertise.

Coatings already enable nonstick cookware several ways, including using grafted siloxanes, fluorinated polymers, and micropatterned textures. Automotive surfaces can use some of the same science. “If you think about the proteins and carbohydrates you may cook with and the way they interact with that surface, it’s similar to a road environment and the insect that may hit your car,” says Peter Votruba-Drzal, senior global technical director in PPG Industries’ automotive division.

Self-cleaning coatings may also reduce maintenance and downtime. Substances such as titanium dioxide can catalytically break down gunk using solar energy, a trick already used in architectural glass to make office building exteriors stay cleaner.

The challenge with vehicle coatings is making them last, Votruba-Drzal says. “The frontier here is getting to the durability that’s required for its service life.”

Clean lenses on good sensors in working order get you only part of the way. The objects they’re looking at need to stand out in a way that registers with a computer’s vision. Road signs and markings rely on retroreflection, an optical trick that sends light more or less back to where it came from.

Parts and labor

Autonomous and electric cars bring a new set of chemical challenges to automotive chemistry. Here are a few technologies for which new materials are making an impact.

Composite structural surfaces

If the car does the driving, the humans can work or play. That means interior components such as seats need to take up less room, and people will be more aware of their look and feel. Covestro says its Maezio carbon fiber–polycarbonate tapes can provide both strength and an attractive finish, all with less mass than the metal, plastic, and fabric of today’s components. Depending on the object’s design, carbon fiber tapes can be stronger than magnesium or aluminum, at two-thirds or half the density, respectively. As a thermoplastic composite, the tapes are also easier to manufacture and recycle than the typical thermoset composite.

Coolants and lubricants for electric motors

The fluids in some electric-vehicle motors are based on hydrocarbons, much like motor oil is today. But they face a long list of requirements. For one thing, the fluids pull heat away from the motors and lubricate them at the same time. So they need to be thermally conductive and electrically insulating. They also need to hold up to heat and shear for a long time, as vehicle makers aim for fluids that last the whole lifetime of the vehicle. And they need to be chemically compatible with a range of metals, plastics, and ceramics. Afton Chemical says specialty additives will be key to meeting all those needs.

IR-reflective body paint

New coatings from PPG Industries look like any of a full range of colors to the human eye but appear bright white in the near-infrared (NIR) wavelengths used by computer vision systems. A special primer coat is highly reflective in the IR range, especially in the NIR around 905 nm. Inorganic pigments in the next coating layer transmit most or all NIR light, which humans can’t see, but absorb in the visible light ranges needed to create color. As a bonus, the coatings help cars stay cooler in warm weather—reducing the demand for air-conditioning and thus extending the range of electric vehicles.

Machine-readable road markings

Even the lowest levels of computer-assisted driving, such as a warning when you drift out of your lane, require cameras to read the road. To be more visible, road markings and signs use retroreflection, an optical effect in which light is sent back to its source. Many lane lines use glass beads embedded in the marking material to retroreflect the light from headlamps and sensors. Ceramic beads from 3M with higher refractive indices, light-colored cores, and varying sizes return more light in more road conditions back to the driver—be it a human or an algorithm. Signs and some lane tapes use prisms instead, which are more efficient but also more expensive.

Silicone sealants for sensors

Autonomous vehicles use a combination of lidar, radar, and cameras to see. Those devices contain sensitive electronics that need to be protected from dirt and dust for the lifetime of the vehicle. But with all the high-voltage electricity flying around electric motors and artificial intelligence systems, those sealants also need to provide grounding and electrical shielding. And they must allow heat to dissipate from the processors. Silver and carbon black can enhance or suppress conductivity of silicones, and ceramic oxides can support thermal conductivity, Dow says, if the manufacturer knows how to integrate them into the silicon-oxygen polymer matrix.

Thermoplastics for battery cases

As batteries get bigger and more powerful to overcome driver anxiety about the vehicles’ range, the casings and adhesives that hold and protect them have to get better too. They need to be strong, fire resistant, and electrically insulating while also being lightweight—a tall order for metals. Thermoplastics can do the job, according to Sabic, because of the low temperature in a battery compared with an internal combustion engine. Which is good, because regulations requiring electric-vehicle batteries to be recyclable are on the books in Europe and in the works elsewhere, taking thermoset polymers out of the game.

Credit: Chris Philpot
09841-cover-graphic.jpg
Credit: Chris Philpot

Parts and labor

Autonomous and electric cars bring a new set of chemical challenges to automotive chemistry. Here are a few technologies for which new materials are making an impact.

IR-reflective body paint

New coatings from PPG Industries look like any of a full range of colors to the human eye but appear bright white in the near-infrared (NIR) wavelengths used by computer vision systems. A special primer coat is highly reflective in the IR range, especially in the NIR around 905 nm. Inorganic pigments in the next coating layer transmit most or all NIR light, which humans can’t see, but absorb in the visible light ranges needed to create color. As a bonus, the coatings help cars stay cooler in warm weather—reducing the demand for air-conditioning and thus extending the range of electric vehicles.

Thermoplastics for battery cases

As batteries get bigger and more powerful to overcome driver anxiety about the vehicles’ range, the casings and adhesives that hold and protect them have to get better too. They need to be strong, fire resistant, and electrically insulating while also being lightweight—a tall order for metals. Thermoplastics can do the job, according to Sabic, because of the low temperature in a battery compared with an internal combustion engine. Which is good, because regulations requiring electric-vehicle batteries to be recyclable are on the books in Europe and in the works elsewhere, taking thermoset polymers out of the game.

Machine-readable road markings

Even the lowest levels of computer-assisted driving, such as a warning when you drift out of your lane, require cameras to read the road. To be more visible, road markings and signs use retroreflection, an optical effect in which light is sent back to its source. Many lane lines use glass beads embedded in the marking material to retroreflect the light from headlamps and sensors. Ceramic beads from 3M with higher refractive indices, light-colored cores, and varying sizes return more light in more road conditions back to the driver—be it a human or an algorithm. Signs and some lane tapes use prisms instead, which are more efficient but also more expensive.

Composite structural surfaces

If the car does the driving, the humans can work or play. That means interior components such as seats need to take up less room, and people will be more aware of their look and feel. Covestro says its Maezio carbon fiber–polycarbonate tapes can provide both strength and an attractive finish, all with less mass than the metal, plastic, and fabric of today’s components. Depending on the object’s design, carbon fiber tapes can be stronger than magnesium or aluminum, at two-thirds or half the density, respectively. As a thermoplastic composite, the tapes are also easier to manufacture and recycle than the typical thermoset composite.

Silicone sealants for sensors

Autonomous vehicles use a combination of lidar, radar, and cameras to see. Those devices contain sensitive electronics that need to be protected from dirt and dust for the lifetime of the vehicle. But with all the high-voltage electricity flying around electric motors and artificial intelligence systems, those sealants also need to provide grounding and electrical shielding. And they must allow heat to dissipate from the processors. Silver and carbon black can enhance or suppress conductivity of silicones, and ceramic oxides can support thermal conductivity, Dow says, if the manufacturer knows how to integrate them into the silicon-oxygen polymer matrix.

Coolants and lubricants for electric motors

The fluids in some electric-vehicle motors are based on hydrocarbons, much like motor oil is today. But they face a long list of requirements. For one thing, the fluids pull heat away from the motors and lubricate them at the same time. So they need to be thermally conductive and electrically insulating. They also need to hold up to heat and shear for a long time, as vehicle makers aim for fluids that last the whole lifetime of the vehicle. And they need to be chemically compatible with a range of metals, plastics, and ceramics. Afton Chemical says specialty additives will be key to meeting all those needs.

Most road signs use prismatic sheeting, in which light reflects off three perpendicular surfaces and ends up reversing direction. That material is generally too expensive for the miles and miles of lane lines that stretch across the globe. Instead, road crews embed little beads into the lane-line material, which is a tape or thermoplastic resin in most cases.

Basic beads are made of glass. Light bends as it enters the bead, reflects off the lane-line resin, and bends again when exiting the bead. The result is similar to prismatic sheets’, though the cone of light returning from beads is more diffuse.

Although humans are decent at picking out lane lines, even when they’re faint from fading or rain, computer vision systems struggle. So lane lines need better beads. 3M and other companies have come out with beads made of metal oxide ceramics with higher refractive indices that work well in wet conditions. The ceramics also last longer, 3M says.

In road markings, everyone wants the same things: white and yellow. Cars are more colorful. The trouble is that some popular car colors, especially black, absorb a broad spectrum of light wavelengths, including the NIR that’s central to computer vision systems. Eggplants helped solve the problem.

“If you look at an eggplant, you see the dark purple skin,” Votruba-Drzal says. “But if in the middle of summer you touch that skin, you’ll notice it’s cool. The reason it’s cool is because it’s IR transparent, and underneath that purple skin is the white flesh of the eggplant, so it’s IR reflective.”

Chemists and engineers first adapted the eggplant concept to aerospace coatings, for which they used it to control heat in airplanes. On the ground, it’s perfect for making cars simultaneously rich in color for humans and bright white for machines.

As a bonus, the IR-reflective coatings also help vehicles stay cool in hot weather. In an electric car, where the air-conditioning that is needed to keep passengers cool is a major battery drain, that reduced heat absorption translates to greater range. And range anxiety—worry about an electric car running down its battery and getting stuck—is an often-cited barrier to broad adoption of electric vehicles.

Related pigments still in the works are radar-transparent colors for plastic body panels. If you look on the bumpers of most late-model cars—both conventional ones with bumper-impact warnings and fully autonomous vehicles—you’ll see a set of little circular badges. Those are radar units, and they stick out because the body panels block too much of the radar signal. Radar-transparent body panels would let automakers drop those intrusions from their sleek, futuristic designs.

Lidar, radar, and camera systems are complex. To keep them working well, they need housings that isolate them from dirt and dust and shield them from electrical interference coming from the batteries, motors, accessories, and other sensors. Electrically conductive silicone sealants play a role here, completing grounding and shielding circuits that run through the sensor housings.

Dow and other silicone manufacturers generally instill conductivity by adding particles of silver and other metals, or carbon black into their sealants.

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Another demand on sealants is thermal management. “The vehicle of the future is going to be a high-end computer on wheels,” says Jeroen Bello, Dow’s global marketing director for mobility. “The vehicle is really the most harsh environment for electronics. The car can heat up or be very cold. You have the vibration; you have the UV.” And as computer components get smaller and computationally denser, they give off more heat per square centimeter that needs to dissipate.

Many device designs include coating circuit boards in a nonconductive silicone sealant. But a permanently clean circuit board is of no help if it overheats, so these coatings also need to conduct heat away.

This category of silicone must be electrically insulating so it doesn’t short out the board it protects. Bello says ceramic oxide blends help silicone wick away the heat.

Bello says sharing chemical details isn’t giving away the farm. Silicone makers keep to themselves the nuances of particle shape and size, blending methods, and curing chemistry. “We’ve been in this space for decades,” he says. “It’s a very comfortable zone. The electrification of the car enables us to expand our portfolio, have the solutions for today, and work on the solutions for the future.”

Surfaces and structure

Imagine you’re in a fully self-driving car. You could watch the road, the gauges, and the indicator lights. But after a while, you won’t. Florian Dorin, who leads the mobility team for Covestro’s thermoplastic composite business, expects rider attention to shift to the interior of the car. People traveling but not driving will notice the textures and patterns of the seats, floors, and ceilings. And they’ll start to demand that a greater share of that interior space be available for their use.

At the same time, industry insiders expect accelerated demand for lighter-weight materials to maximize range and energy efficiency. Chemical companies like Covestro aim to get ahead of the trend by developing thin, strong, low-density materials for interior components of self-driving cars.

A door panel in a 2007 Honda Odyssey might have six to seven layers of sheet metal, plastics, foam, and finish. “It looks like a big fat onion; it’s a real thick part,” Dorin says. He says Covestro’s Maezio structural tape combines structure and finish in one material, which might let designers make a door with just three layers, saving weight and opening more room in the interior. A composite of carbon fiber and polycarbonate resin, the tape is strong and aesthetically pleasing, he says.

09841-cover-cruise.jpg
Credit: General Motors
On Oct. 15, California gave General Motors permission to remove the backup drivers from some of its self-driving car tests in San Francisco.

Covestro engineers are also exploring polycarbonate as a structural material on its own. The firm is working on a sandwich of regular and expanded polycarbonate foam that could offer strength and thermal insulation for door and floor panels. And making a multifunctional part out of a single polymer would aid recyclability, Dorin says.

Polycarbonate’s thermoplastic nature also helps recyclability. Thermoplastics become moldable above their glass transition temperature. For polycarbonate, that’s around 145 °C, which is high enough that the material stays rigid in automotive conditions. But in a recycling facility, polycarbonate can be remolded repeatedly, unlike thermoset plastics, which harden irreversibly.

Electricity and beyond

You can make an autonomous car with a conventional engine or hybrid power train. But most experts expect all-electric vehicles to rule the road. The computers and sensors in a self-driving car already need higher-voltage systems than a standard 12 V car battery can offer. And the environmental arguments for electric vehicles are strong.

Electrification arguably affects the chemical industry more than automation does. No more glycol-based engine coolant or additive-rich transmission fluid. Conventional motor oil is also out, but we’ll still have lubricants. And batteries, rich in chemistry in their own right, need to be housed in tough and lightweight cases.

The relatively low temperatures in electric vehicle batteries, up to about 60 °C, make thermoplastics a good choice for battery casings and separators, says Mark Armstrong, a senior scientist working on plastics at the chemical maker Sabic. Sabic’s entries in this market include its Noryl thermoplastics, which combine polystyrene with either polyphenylene oxide or polyphenylene ether; the ratio of polymers changes the glass transition and melting temperatures.

Unlike metal battery cases, ones made of thermoplastic can include additives that impart useful properties, such as fiberglass for strength, fire retardants, or steel fibers for electrical shielding, Armstrong says. Other blends can conduct heat or electricity or insulate against either one. Steel, aluminum, and magnesium still have places in battery and motor systems, but specialty polymers offer engineers a menu of material properties at lower weight, an omnipresent goal in electric vehicles.

With batteries, it’s temperature gradients; that’s the thing that kills them.
Adam Banks, e-mobility marketing manager, Afton Chemical

Motors in autonomous vehicles are both opportunity and threat for makers of automotive fluid. “It’s the electrified part that has the most direct bearing on fuels and lubricants additives,” says Adam Banks, e-mobility marketing manager for Afton Chemical, which specializes in fuel and lubricant additives.

Afton has been dealing with creeping electrification since the hybrid Prius and Honda Insight launched in the late 1990s. A hybrid’s internal combustion engine has a hard job, Banks explains. It has to cope with cold starts at high speeds if the electric motor takes it all the way to the highway before the engine kicks on. “That’s quite a violent way to wake up in the morning if you’re an engine,” Banks says.

Or the gasoline engine might sit unused for weeks if the hybrid’s owner mostly does short trips between spots with charging stations, leading water to condense and build up.

Harsh demands on fluids are not all bad for Afton, because its business is chemical additives that make fluids perform better. Electrification will eventually bring overall fluid volumes down, Banks says, but volumes were decreasing anyway as chemical and mechanical innovation extends the useful lives of lubricants, hydraulic fluids, and coolants.

Coming electric motor technology could offset some of the decline in chemical use. The electric motors in automotive use today are dry—they don’t use bulk lubricant, and they’re cooled passively or with fluid channels on their outsides. Banks says newer electric motors will put oil in direct contact with moving parts to lubricate and cool them. Future electric cars may also have multiple gears, creating a need for transmission fluid that isn’t present in today’s electric cars.

A few years on, Banks says, fluids for directly cooling batteries could represent another high-volume segment for Afton. Today’s electric cars cool the batteries by running a water-glycol blend over metal fins sticking out of the cells. But that approach might not remove heat fast enough to protect the cells under rapid charging and discharging. “With batteries, it’s temperature gradients; that’s the thing that kills them,” Banks says.

Already, the McLaren Speedtail, a hybrid supercar released this year, pumps a nonconductive oil through its battery pack to keep an even, managed temperature as current blasts out of the batteries into the motors.

Companies offering performance chemicals and materials need to be quick on their feet in today’s fast-changing mobility market. Even working directly with automakers during the design phase isn’t enough. Banks says Afton has ramped up its proactive R&D in the past 4 years to anticipate customers’ needs rather than wait for them to show up with a problem.

The challenges are big, but so is the opportunity for firms that can serve up the materials that bring an automaker’s designs to life. “This is your vision of the future” is what Covestro’s Dorin says he tells his customers. “And we are here because we have the materials solution to make this vision come true.”

CORRECTION:

This story was updated on Nov. 2, 2020, to correct two errors. Electric vehicle batteries, not motors, operate at temperatures of up to about 60 °C. Motors can get up to around 95 °C. Also, the story incorrectly attributed to Mark Armstrong of Sabic a statement that fiberglass imparts fire retardation to thermoplastics. Other firms make that claim, but Sabic does not.

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