Skyprene Chloroprene Rubber Grades for Adhesive Applications

Polychloroprene rubber (CR) is widely recognized as a foundational polymer in high-performance dry contact adhesives due to its exceptional initial tack, oil resistance, flame retardancy, and superior bonding strength. However, selecting the appropriate CR grade requires a precise balance between crystallization rate, Mooney viscosity, solution thixotropy, and environmental compliance.

This article breaks down the Skyprene Adhesive Applications series into three primary categories—General-Purpose, Heat Resistant (Carboxylated), and Eco-Friendly—to assist formulators in optimizing adhesive performance.

1.General-Purpose Grades: Balancing Crystallization Rate and Viscosity

General-purpose grades are classified primarily by their crystallization speed and Mooney viscosity, which directly govern green strength, open time (tack retention time), and sprayability.

Fast Crystallization Grades (G-Series)

High Initial Strength & Spraying Performance: Grades such as G-40S, G-40S-1, G-40T, G-70, G-41H, G-42, G-55, and G-66 offer rapid strength development.

• Specialized Functional Varieties:

Low Viscosity Spraying: SKYPRENE G-42 features lower Mooney viscosity (36-48), making it an ideal base for sprayable formulations.

MMA Grafting: G-40S-1 is engineered for MMA-grafted adhesives, specifically targeting soft PVC and synthetic leather bonding with minimal solution coloration.

Improved Mastication: G-41H utilizes a thiram-stabilized system, facilitating easier mastication and superior phase-separation resistance.

Crosslinking & Rheology Control: G-55 exhibits higher reactivity toward isocyanates, while G-66 provides higher thixotropy and reduced solution fluidity for anti-sagging applications.

Medium Crystallization Grades (Y-Series)

Versatile Processing: Y-30S, Y-30H, Y-30HA, and Y-31 offer a balanced crystallization rate, allowing for longer tack retention compared to the G-series while maintaining good heat resistance.

Viscosity Hierarchy: Ranging from Y-31 (Mooney 90-110, lower viscosity) to Y-30HA (high solution viscosity up to 1900-2600mPa·s, these grades allow formulators to tune solid content and rheology.

Crystallization-Resistant Grades (B-Series)

Extended Open Time: SKYPRENE B-30S, B-31, B-10, and B-5 exhibit slow crystallization or non-crystallizing behavior.

Tack Retention Modifiers: B-5 and B-10 are primarily used as blending modifiers to extend the tack retention time of faster-crystallizing bases without compromising ultimate flexibility.

2. Heat Resistant Grades: Carboxylated CR Polymers

For high-temperature applications (such as automotive interiors or structural laminates exceeding 80℃, carboxylated grades - 510, 510L, 570, 580, and 580H—are recommended.

3. Eco-Friendly Grades: Toluene-Free Formulation Stability

To comply with environmental regulations reducing aromatic solvents (Benzene, Toluene, Xylene - BTX), formulators must transition toward mixed solvent systems (e.g., Cyclohexane, Ethyl Acetate, Normal Hexane, Acetone). However, replacing toluene often induces phase separation during storage.

To resolve this issue, Eco-Friendly grades were developed: Y-30SN, Y-30SAN, Y-30HAN, and G-40TN.

Storage Stability Comparison

Standard SKYPRENE Y-30S in Toluene-Free Solvent: Shows clear phase separation after 1 month of storage at 23℃.

Eco Grade Y-30SN in Toluene-Free Solvent: Demonstrates zero phase separation even after 3 months of storage at 23℃, maintaining complete solution homogeneity.

Peel Strength Retention: Y-30SN delivers equivalent or higher initial peel strength (99 -171 N/25mm) and heat strength (62 N/25mm at 80℃) compared to standard toluene-containing systems.

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