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Thermoplastic elastomers for the production of seals are the most widely represented on the Russian market. Considering the extreme operating conditions of seals — from winter temperatures as low as –50 °C in Irkutsk to southern regions of Russia, where black seals can heat up to +70 °C under direct sunlight — TPE grades for window and door seals represent one of the most technically demanding yet underestimated material categories. Due to the high level of competition among TPE manufacturers in Russia, quality in this segment is often sacrificed in the pursuit of lower prices, leading to unsatisfactory performance of certain grades.
Based on our experience and in accordance with the requirements of GOST 30778-2001 and GOST 31362-2007, the key performance characteristics of TPEs for seal production include:
- residual compression set;
- shrinkage after long-term exposure to low and elevated temperatures;
- increase in hardness at sub-zero temperatures;
- resistance to cracking at high temperatures;
- modulus of elasticity;
- resistance to thermal ageing, ozone ageing, and UV ageing.
At the same time, most consumers of TPE do not conduct incoming inspection of these critical properties. In practice, the majority of incoming quality control is limited to just three indicators: hardness, density, and melt flow rate (MFR or PTR).
These parameters provide only indirect information about material quality. For example:
- An MFR above 20 g/10 min makes it difficult to produce seals with precise geometry. A high MFR is often a sign of insufficient SEBS rubber content in the formulation.
- High density typically indicates excessive filler content, which reduces cost but negatively affects performance.
As a result, the market often offers TPE grades with identical hardness, density, and MFR values, but with dramatically different functional properties that are crucial for seal durability and reliability.
