HTBN (Hydroxyl-Terminated Butadiene-Acrylonitrile Rubber; Hydroxyl-Terminated Liquid Nitrile Rubber) commonly known as nitrile hydroxyl rubber, is a telechelic liquid rubber with reactive hydroxyl groups (–OH) at both ends of the molecular chain and a main chain copolymerized from butadiene and acrylonitrile.

• Structure: Copolymer of butadiene and acrylonitrile, end-capped with hydroxyl groups; nitrile groups (–CN) impart oil/solvent resistance, and terminal hydroxyl groups enable cross-linking with isocyanates, epoxies, etc.

• Appearance: Pale yellow to amber transparent viscous liquid.

• Typical Key Specifications:

• Molecular weight: 3,500–6,000

• Acrylonitrile content: 10%–28% (high nitrile ≥20%, medium nitrile 13%–17%)

• Hydroxyl value: 0.3–1.0 mmol/g

• Viscosity (40°C): ≤300 Pa·s (increases with nitrile content)

Core Advantages: Excellent oil resistance, aging resistance, low-temperature flexibility, strong adhesion, room-temperature curability, combining the processability of liquid rubber with the durability of solid nitrile rubber.

Differences from CTBN/HTPB

1. Toughening of Epoxy Resins/Thermosetting Resins (Most Mainstream)

• As an epoxy toughening agent (replacing CTBN),  it improves the peel strength, impact resistance, and humidity-heat resistance of epoxies while reducing brittleness; suitable for structural adhesives, composite materials, and electronic encapsulation.

• Mechanism: Pre-reacts with epoxy to form a sea-island structure, where the rubber phase absorbs impact energy without significantly lowering Tg.

2. Polyurethane (PU) Elastomers and Adhesives

• Cross-links with MDI/TDI and other isocyanates to prepare oil-resistant PU elastomers, seals, rubber rollers, and conveyor belts; superior to ordinary PU in oil resistance, aging resistance, and low-temperature flexibility.

• Solvent-free room-temperature curable adhesives: Bonds metals, rubbers, plastics, and composite materials for automotive, marine, and aerospace structural bonding.

3. Oil-Resistant/Anti-Corrosion Coatings and Sealing Materials

• Oil-resistant and anti-corrosion coatings for ships, marine engineering, and chemical equipment: Resists seawater, salt spray, acids, alkalis, and fuel erosion.

• Automotive oil seals, O-rings, chassis seals, oil pipeline liners, and hydraulic system seals; oil resistance + high and low temperature resistance (–40°C to 120°C).

4. Electrical/Electronic Potting and Insulation

• Potting compounds and insulating sealing materials for electrical/electronic components: Moisture-proof, shockproof, weather-resistant, and electrically insulating, used for high-voltage devices, sensors, and power modules.

5. Aerospace

• Grain cladding/thermal insulation layers for solid rocket motors, and impact-resistant modification of aerospace composites; extreme environment resistance + high mechanical properties.

6. Rubber/Plastic Modification

• Reactive plasticizer for nitrile, neoprene, and butyl rubbers: Improves processability, enhances interfacial adhesion, and resists migration.

• Oil-resistant modifier for PVC, nylon, etc.: Replaces DOP/DBP, solves plasticizer migration, and improves oil and cold resistance.