Polybutadiene rubbers are highly elastic and have a very high degree of resistance to dynamic stress, and retain these properties even at extremely low temperatures. Blending natural rubber or styrene butadiene rubber with Buna CB improves the abrasion resistance, crack resistance and heat build-up under dynamic load.

Butadiene rubbers are produced by the solution polymerization process with the aid of organometallic catalysts. The catalyst system, which is characterized by the particular metal (neodymium, cobalt, lithium or titanium), influences the microstructure and macrostructure of the polymers and therefore the properties. LANXESS currently produces Nd, Co and Li grades.

The Li-BR grades have a medium cis-1,4 content and a considerably higher glass transition temperature, and are entirely amorphous. These grades have a very narrow molecular weight distribution and low degree of branching.

Name    Plant    Type    ML 1+4    Remark
Buna CB 21    Dormagen    Nd-BR    73    highly linear
Buna CB 22    Dormagen / Pt. Jérôme / Orange    Nd-BR    63    highly linear
Buna CB 23    Dormagen / Orange    Nd-BR    51    linear
Buna CB 24    Dormagen / Pt. Jérôme / Orange    Nd-BR    44    linear
Buna CB 25    Dormagen     Nd-BR    44    long chain branched
Buna CB 29 MES    Dormagen     Nd-BR    37    oil extended
Buna CB Nd 40    Cabo    Nd-BR    41,5    linear
Buna CB Nd 40 H    Cabo    Nd-BR    44    linear
Buna CB Nd 60    Cabo    Nd-BR    63    linear
Buna CB 55 NF    Pt. Jérôme    Li-BR    55    linear
Buna CB 60    Pt. Jérôme    Li-BR    60    star branched
Buna CB 45 B    Cabo    Li-BR    45    linear
Buna CB 55 B    Cabo    Li-BR    55    linear
Buna CB 55 H    Cabo    Li-BR    54    linear
Buna CB 55 L    Cabo    Li-BR    51    linear
Buna CB 70 B    Cabo    Li-BR    70    linear
Buna CB 1220    Orange    Co-BR    40    branched
Buna CB 1221    Orange    Co-BR    53    branched
Buna CB 1203    Orange    Co-BR    43    branched
Buna CB 45    Orange    Li-BR    45    linear

Applications
Typical applications are tires, conveyor belts, caterpillar tread blocks, footwear soles, V-belts; they can be blended with NR for goods having thick sections and needing high resistance to reversion, e.g. buffers, roll covers needing high abrasion resistance; seals, profiles and other goods, particularly those produced by injection molding. Provided that the compounds are formulated and processed correctly, the vulcanizates have good resistance to aging, reversion, abrasion and flex cracking, good low temperature flexibility and high resilience.

Key Properties

• good resistance to aging and reversion

• excellent abrasion resistance

• low dynamic fatigue resistance good low-temperature flexibility

• high resilience