How To Select The Right SIS Grade for Adhesive Applications?

Adhesives are widely used in packaging, construction, automotive, electronics, and medical sectors, covering applications such as tapes, labels, coatings, and various bonding and sealing uses. Each use case has different requirements for initial tack, holding power, melt viscosity, heat resistance, and slitting performance.

In adhesive manufacturing, choosing the right SIS (Styrene-Isoprene-Styrene) grade is crucial for achieving both performance and cost-effectiveness.

Key SIS Technical Parameters and Their Impact on Adhesive Properties:

1. SIS Structure (Linear vs. Star):

Star-shaped SIS generally results in adhesives with lower melt viscosity, stronger holding power, higher peel strength, and higher softening point—ideal for high-performance applications.

2. Block Ratio (S/I):

The ratio between polystyrene (S) and polyisoprene (I) segments significantly affects adhesive properties.

Higher S/I ratio usually leads to:

→ Lower initial tack

→ Greater holding power

→ Lower melt viscosity

→ Higher softening point

3. Molecular Weight:

Higher molecular weight SIS: higher viscosity, stronger cohesion, but lower flowability.

Lower molecular weight SIS: better flow and coating ability, but may reduce cohesion.

Select based on your application’s processing and performance needs.

4. Diblock (SI) Content:

Increasing SI content can lead to:

Higher initial tack

Higher holding power (up to a point)

Higher 180° peel strength (before declining)

Lower melt viscosity

Lower softening point

Better slitting performance

5. Other Technical Factors:

Glass transition temperature (Tg): Determines operating temperature range.

Thermal stability & aging resistance: Ensure long-term performance.

Chemical resistance: Crucial in specific environments.

Electrical properties: Key for insulation-grade adhesives.

Recommended SINOPEC SIS Grades & Their Features:

Initial Tack:

1105: Excellent tack, long holding time, for general pressure-sensitive tapes and labels.

1209: Mainly for hygiene hot-melt adhesives but also shows excellent cohesion and tack.

1126: High initial tack and great slitting performance—ideal for label adhesives.

Holding Power:

1105: Long-lasting hold, balancing with tack.

1209: Strong holding with low melt viscosity and heat resistance—great for demanding environments.

1125: Good overall performance with reliable holding and heat resistance.

Melt Viscosity:

1209 & 1125: Low melt viscosity enables efficient coating and production.

Other Benefits:

Heat resistance: 1209 and 1125 perform well in high-temperature conditions.

Slitting performance: 1126 and 1125 are suitable for high-speed, automated die-cutting processes.

If you're looking for SIS, SBS, SEBS, SEPS, or SSBR raw materials, feel free to DM us or leave a comment — our technical team is ready to assist with tailored recommendations.