Car tires may look like rubber lumps from the outside, but they contain various reinforcements that support the weight of the vehicle while enabling safe movement. Tire reinforcements are mainly composed of fabric-based tirecord and metal-based steelcord. A belt made of thin iron wires woven on the inside of the rubber tread reduces road impact during driving, while the carcass supports the load, maintains air pressure, and withstands external shocks.
The carcass forms the backbone of the tire and helps maintain its shape. Occasionally, the side of a tire bulges out like a bulge, which is due to the breakage of the tirecord that composes the carcass from external shocks such as potholes, causing internal pressure to expand and resulting in the phenomenon of cord protrusion.
Tirecords need to be lightweight yet strong, so they are primarily made from high-strength, low-weight polyester (PET) fabric. HS HYOSUNG's industrial materials subsidiary, HS Hyosung Advanced Materials, occupies about 50% of the global PET tirecord market. When Hyosung first produced domestic tirecords using nylon in 1968, it later developed PET tirecords in 1978 using its own technology by increasing the strength of polyester yarn originally used for medical purposes.
A single tire weighs about 10 kg, and the weight percentage of PET tirecord is around 5% (about 500 g). Making tirecords from polyester has lightened tires and increased fuel efficiency.
HS Hyosung Advanced Materials is outpacing its 2nd and 3rd ranked competitors by more than 30 percentage points. Top 10 tire corporations worldwide, including Michelin, Bridgestone, Goodyear, Continental, and Hankook Tire, use HS Hyosung Advanced Materials' PET tirecords. This means that one out of every two passenger car tires on the world's roads contains PET tirecord from HS Hyosung Advanced Materials.
In addition to tirecords, HS Hyosung Advanced Materials produces all types of tire reinforcements, including steelcord and bead wire (which secures the outermost part of the wheel, the rim). Sales from tire reinforcements account for about 40% of their annual revenue (32.02 trillion won in 2023).
The source of competitiveness lies in the yarn, which is the root of Hyosung. Tirecord material is essentially fabric woven from yarn. Creating polymerized high molecular weight PET chips from raw materials is the beginning of tirecord production. As environmentally friendly materials become increasingly important in tires, bio PET made from plant-based raw materials and materials extracted from recycled PET bottles are being used more frequently, replacing traditional petroleum-based PET.
The yarn goes through a spinning process to be made into its final form. A single strand of yarn consists of 300 to 400 filaments, thinner than human hair. The physical properties of the yarn vary depending on temperature, speed, and emulsions. Anseonghun, CEO of HS HYOSUNG, noted, "The physical properties of the yarn itself must be good for the subsequent processes to improve, making the spinning technology to draw the yarn the most basic and important process in tirecord production."
Two strands of yarn twisted together form the cord. Pulling on a single strand does not stretch much, but by twisting two strands through the twisting process, they stretch better and are less likely to break due to the twisting. A strand of twisting that is less than 1 mm thick can support over 20 kg.
In the weaving process, about 1,500 cords are attached together to be processed into a fabric form. Finally, to ensure that the tirecord adheres well to the tire rubber, a rubber component called latex is coated on the surface and heat-treated, completing the tirecord. The key is to ensure that the adhesion with the rubber remains intact even in extreme environments. Tire manufacturers cut the tirecord fabric into pieces and insert them into the tires.
Just as the pattern on the rubber tread on a tire varies, the physical properties of the tirecord used also differ by manufacturer. Lee Taejeong, executive director of HS Hyosung Advanced Materials, stated, "Just as semiconductors can be custom-made based on customer demands, tirecords are also made differently according to the physical properties required by tire companies." Each tire manufacturer has different standards for strength, shape stability, durability, and adhesion, leading to varying results.
As various vehicles such as electric cars and large sports utility vehicles (SUVs) are emerging, tire technology is also evolving. Developing high-strength, high-performance materials required for electric car tires and large SUV tires distinguishes tirecord manufacturers' competitiveness. Electric car tires and large SUV tires are larger in size. To enhance fuel efficiency, the technology lies in making tires lighter while maintaining the same strength. The secret to lightweight tires is to make the tirecords thinner and increase the rubber adhesion to reduce rubber usage.
HS Hyosung Advanced Materials uses aramid (Aromatic Polyamide) fibers, which are about five times stronger than steel and are not easily combustible, for electric vehicle tirecords. This is a hybrid tirecord (HTC) product made from a blend of aramid and nylon. Electric vehicle tires must support the weight of batteries weighing hundreds of kilograms and have excellent rolling resistance. Because electric vehicle tires use more tirecord than regular tires, they are considered high-value-added products.
Currently, electric vehicle tires and tirecords each account for about 10% of total tire production. Although the electric vehicle market has passed the initial rapid growth phase and is currently experiencing a chasm in demand, the demand for electric vehicles is expected to rise again due to the expansion of charging infrastructure and countries' carbon neutrality goals.
This executive noted, "By 2030, the share of electric vehicles in total automobiles is expected to rise to 50%, and the share of electric vehicle tires is expected to reach 30%, so the demand for high-performance tirecords dedicated to electric vehicles is expected to increase accordingly."