kumiseos

Kumiseos is a Finnish term that denotes the rubber compound used to produce elastic products. It refers to a formulated blend of elastomer polymers, fillers, reinforcing agents, curing systems, and processing aids selected to achieve targeted properties such as elasticity, strength, heat resistance, and wear performance.

The base of a kumiseos is usually one or more elastomer polymers. Common choices include natural rubber (NR) and synthetic rubbers such as styrene-butadiene rubber (SBR), butadiene rubber (BR), nitrile rubber (NBR), and ethylene propylene diene monomer (EPDM). Fillers and reinforcing agents, notably carbon black or silica, are added to adjust strength, durability, and abrassion resistance. Processing oils, plasticizers, antioxidants, antiozonants, and lubricants are used to tailor processability and aging resistance. The curing system, often sulfur-based with accelerators, or alternative peroxides, determines the vulcanization behavior and final elasticity.

Manufacturing involves mixing or milling the ingredients into a homogeneous compound, followed by shaping through calendering, extrusion, or molding, and finally vulcanization (curing) in a heated mold or press. Conditions vary by formulation and application but typically require controlled temperature and time to achieve complete crosslinking without degrading the polymer.

Applications of kumiseos span tires, seals, hoses, gaskets, belts, and vibration-damping components. Properties such as tensile strength, elongation, abrasion resistance, heat aging, and oil resistance are tested to meet performance standards. In Finnish industry, kumiseos is the general term for these formulations; in English, the equivalent concept is called a rubber compound.