Liquid Polybutadiene

How it’s Made: Polymerization of Butadiene

The term polybutadiene refers not to just one compound but to a group of polymers formed by the polymerization of 1,3-butadiene. This organic compound is used almost exclusively in the production of synthetic rubber and can be produced from various fossil fuels or synthesized renewably from ethanol.

As it’s polymerized, 1,3-butadiene forms varying ratios of cis, trans, and vinyl polybutadiene, which can be controlled using various catalysts to produce a material best suited to a particular application. Polybutadiene may also be functionalized, or modified, to further tailor its properties.

To manufacture liquid polybutadiene rather than solid polybutadiene, catalysts and processes that produce lower molecular weight are used, which mainly include anionic polymerization and radical polymerization.

Applications of Liquid Polybutadiene

As a liquid synthetic rubber and additive that provides excellent material properties, liquid polybutadiene is used in a wide variety of applications.

Liquid polybutadiene is commonly used in car tires, where it provides abrasion resistance, lower rolling resistance, longer tire lifespan, and better fuel economy. It also sees use as an additive in automotive sealants and structural polymer adhesives thanks to its favorable material properties.

Liquid polybutadiene may also be used as a plasticizer or added to heavy-duty hoses, thermoset polyurethane products, printing plates, footwear, hot melt adhesives, pressure-sensitive adhesives, electronics insulation, and other rubber or plastic products.

In coatings, liquid polybutadiene can be used to reduce levels of volatile organic compounds (VOCs). Adding solid fillers increases viscosity and makes the coating difficult to use, so liquid polybutadiene is an ideal alternative for low-VOC coatings.

The use of liquid polybutadiene in coatings enhances film flexibility, improves water and chemical resistance, and ensures stable performance even in low-temperature environments.

Liquid Polybutadiene from Kuraray

Kuraray offers several grades of liquid polybutadiene (L-BR) for use in a wide range of applications, and also provides liquid polyisoprene (L-IR) and liquid polystyrene-butadiene (L-SBR) under the KURARAY LIQUID RUBBER product line.

Kuraray’s liquid polybutadienes offer a low-VOC liquid rubber that is transparent, colorless, and almost completely odorless. Depending on their molecular weight, they can be used as a reactive plasticizer and can replace either rubber or process oil in many formulations.

When used as a plasticizer, the good flowability of Kuraray’s liquid polybutadienes reduces Mooney viscosity and allows for more efficient mixing, saving both time and power. KURARAY LIQUID RUBBER grades are also co-vulcanizable with base rubbers, significantly reducing migration. Together, these properties improve production efficiency, lower power consumption, increase the longevity of mixing equipment and products, and reduce emissions.

Low Vinyl Liquid Butadiene Rubber

Liquid butadiene rubber refers to liquid polybutadiene, a synthetic liquid rubber made from butadiene. These grades of liquid polybutadiene, which are designed with molecular weights lower than solid rubbers and higher than conventional plasticizers, are excellent reactive plasticizers that can co-vulcanize with rubber and prevent bleeding and migration. With a wide variety of viscosities and molecular weights, these grades are suitable for applications from automobile tires to rubber components. Their low glass transition temperatures (Tg), resulting from low vinyl content, make them especially well-suited for use in rubber products designed for cold climates—such as winter tires, snowmobile treads, and conveyor belts.

High Vinyl Liquid Butadiene Rubber

Kuraray’s two grades of high vinyl liquid butadiene rubber can be used as coagents for peroxide curing of EPDM rubber, due to their high vinyl content, which enhances crosslinking efficiency. In EPDM rubber formulations, coagents such as TAC (triallyl cyanurate) are used to enhance cure rate and improve compression set. However, by using these grades as coagents, it is possible to suppress concerns associated with TAC, such as bleeding, odor, and VOC emissions, while achieving excellent cure kinetics and optimum compression set.

Silane-Modified Liquid Butadiene Rubber (GS-L-BR)

This functionalized variant of liquid butadiene rubber, like other KURARAY LIQUID RUBBER products, is an ideal additive in tire rubber. By improving the dispersion of silica, a common filler in tire rubber, GS-L-BR enhances abrasion resistance, fuel economy, grip performance, and longevity.

Safety & Handling

Liquid polybutadiene is a relatively safe substance that is easily processed with typical safety precautions. Avoid contact with skin and eyes, use in well-ventilated areas, and do not ingest. If liquid polybutadiene catches fire, it can produce toxic fumes—it should be extinguished immediately using proper protective equipment. Spilled polybutadiene can simply be cleaned with an absorbent material and properly disposed of. For more information, always consult a safety data sheet before handling a new chemical.