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May 10, 2020 - 2 min

STPE Technology 101

Published by Catherine Lavoie Canuel

Silyl Terminated Polyesther (STPE), the Hybrid Product

STPE is a hybrid product of silicone and polyurethane technologies. Combining these materials brings together the most desirable features of each and creates a durable, high-quality product. STPE technology is engineered to make high-performance products that are also safe for workers and the environment. Other common names for this chemical formula include MS polymer, SPUR, polyether, STP and SMP.

Benefits of STPE Technology

As mentioned, these products are engineered for high performance, and to be a safe and environmentally friendly solution with extremely low VOC content. STPE-based products offer excellent curing speed and perform well under nearly any weather conditions. If the project is carried out in extremely dry conditions, multiple rainy days or anything in between, STPE technology performs consistently. There is no possibility of outgassing, and it can even be applied under water for emergency touch-ups.

As for project considerations, STPE technology is perfect for works that require flexibility in design. Typically, it does not require primers, offers a broad adhesion profile for many types of projects, and is compatible with a wide range of substrates. Upon completion, STPE materials are more paintable than any silicone sealant available.

Comparison With Silicones and Urethanes

When comparing STPE materials to silicones and urethanes, there are many qualities that stand out. STPE-based technologies will typically surpass the elongation characteristics of silicones. They have good adhesion to a wider range of materials and offer better UV resistance than most urethanes. They are also competitive in price with both urethanes and silicones.

By combining the finest qualities of silicones and urethanes, STPE technology offers the best of both worlds. When looking for a product that provides design flexibility with fast curing speed and low VOC content, these products are the perfect solution.

SOPREMA offers great products using STPE technology.

Table 1: Performance Comparison of MS, Polyurethane and Silicone Sealants*

Property MS polymer Polyurethane Silicone
Environmental friendliness 10 5 9
Non-bubbling 10 6 10
Low-temperature gunnability 10 8 10
Slump resistance 10 10 10
Quick curing 10 7 10
Storage stability 10 7 9
Body (tooling) 8 10 8
Weather resistance 8 6 10
Adhesion to various substrates 10 5 8
Mechanical properties 10 10 10
Heat resistance and mechanical stability 9 8 10
Non-dirt pickup 10 10 5
Stain resistance 8 8 5
Paintability with water-based paint 10 10 3
Scale : 10 = excellent; 1 = very poor