Fossil fuels are versatile resources that provide electricity, transportation, and feedstock for many synthetic materials around us. For example, polyurethane (PU) and polyvinyl chloride (PVC), commonly used to create synthetic leathers, are petrochemical-derived raw materials used in everyday products. However, our widespread dependence on fossil-fuel-based materials has caused detrimental consequences for the planet. So, what exactly are petrochemical-derived raw materials, and how are they used to create synthetic plastic-based leathers?
"Currently, artificial leathers have limited recyclability potential...instead, as the materials wear, they continuously shed microplastics, infiltrating the air and water around us."
Where do fossil fuels come from?
Millions of years ago, silt, sand, and rock buried ancient algae and plankton beneath the ocean floor. Over time, organic and inorganic material layers accumulated while pressure and temperature increased. This constant exposure to high heat and pressure transformed the organic material into coal, crude oil, and natural gas.
The two most common fossil fuel extraction methods, mining and drilling, utilize heavy machinery. For example, coal mining takes place in surface mines or underground mines. Both mining techniques require large machines to remove plants, rocks, and soil above to access the coal below. Further, petroleum and natural gas extraction utilizes drills that bore into the earth’s surface. Upon reaching the oil reservoir, pumps and other extraction methods carry the oil above ground.
While fossil fuels derive from natural organisms, their extraction processes contribute to immense environmental degradation. Mines can stretch for miles, clearing forests, removing mountaintops, and destroying wildlife habitats. In addition, oil rigs are typically the size of a ten-story building and often disturb sensitive marine habitats. The lifecycle of these structures can last for decades, causing long-term environmental disruption.
Hydraulic fracturing, or fracking, is one of the most controversial extraction methods. This process injects a highly pressurized mixture of water, sand, and chemicals into gas wells. The induced stress causes cracks in solid shale rock formations to emerge, releasing trapped natural gas and oil. However, fracking produces water waste, and the chemicals used can poison groundwater and drinking water supplies. Additionally, tremors resulting from the fracking process may cause small earthquakes that disrupt transportation pipelines.
After extraction, a network of trucks, ships, and railroads transports natural gas and petroleum to refineries. Here, Crude oil undergoes a distillation process that separates distinct compounds by their boiling points. Next, the compounds are broken down further into simple hydrocarbons, which become the building blocks of polymers. Unfortunately, petroleum refineries use an extensive amount of energy and produce toxic air pollutants and greenhouse gases.
How are synthetic leathers produced?
Synthetic leather creation requires a variety of petroleum-derived components. First, the manufacturer mixes a polyurethane (PU) with a solvent–typically DMF–together, creating a PU resin. Second, they coat the PU resin onto a backer, typically made from polyamide or polyester. Third, to mimic the visual appearance of tumbled leather, the manufacturer applies textured release paper onto the PU resin. Last, the resulting PU-based synthetic leather goes through final processing, dyeing, and finishing to achieve the desired color and finishing effects.
The production of synthetic leather also raises many environmental concerns. The necessary polyamide, polyester substrates, and polyurethane-based coatings derive from fossil fuels. As previously mentioned, their extraction process destroys habitats and pollutes groundwater. Further, the transportation refining process of oil and gas requires tons of energy and releases potent greenhouse gasses into the atmosphere. Finally, fossil fuels are non-renewable resources. They take millions of years to form underneath the surface but only decades to extract. The Earth has a limited supply of fossil fuels that is rapidly dwindling.
Synthetic leather creation and its finishing processes cause further harm to surrounding communities. In fact, during the manufacturing process, the most common solvent used in synthetic leathers, DMF, is frequently released into the air. Research shows that workers and the local communities exposed to DMF have an increased risk of cardiac injury, liver dysfunction, and kidney dysfunction. Finally, some synthetic leather dyeing facilities lack proper wastewater disposal, polluting local drinking water.
Currently, artificial leathers have limited recyclability potential. Their composition, a diverse mixture of synthetic substrates and coatings, creates a complicated and sometimes energy-intensive recycling process. Moreover, artificial leather lacks biodegradability. Instead, as the materials wear, they continuously shed microplastics, infiltrating the air and water around us.
Are there ethical leather alternatives?
Companies value petrochemical-based synthetic leathers for their high performance, durability, and relatively affordable price points. They mimic the texture and look of authentic leather without slaughtering an animal and at a fraction of the cost. Simultaneously, these materials come at a high environmental cost.
While fossil-fuel-based synthetic leathers remain the most common vegan leather on the market, innovative biobased material development is emerging. These new materials target alternative feedstocks–from plants, fungi, microbes, and minerals–curbing our reliance on fossil fuels. While still in production, these novel technologies already show promise as sustainable and ethical material alternatives.
Note: Bucha Bio rebranded to Rheom Materials in January 2024 to better reflect their process and offerings. The new name combines the Greek word "rhéō" (meaning "flow") and "form," describing how a melt-extruder works, where the biopolymers flow into place and then solidify, or form, the final product.
