Chloroprene rubber (CR): properties and applications

Chloroprene rubber (CR, polychloroprene) is a synthetic elastomer produced by polymerisation of the monomer chloroprene (2-chlorobutadiene-1,3). In Russia and the CIS, this material is known as "nairit", while in Western countries the eponym "neoprene" is widespread; it is also known as baypren, butachlor and skyrene. Thanks to its unique combination of properties — resistance to open flame, oils, gasoline, ozone and weathering — chloroprene rubber occupies a special place among synthetic elastomers, serving as a bridge between general-purpose rubbers and high-performance specialty elastomers.

History

Research into chloroprene synthesis began in the 1930s at DuPont (USA). In 1931, chemists under the direction of Wallace Carothers synthesised the monomer, and by 1932 they had launched industrial production of the rubber under the Neoprene brand. During World War II, neoprene replaced natural rubber in various rubber technical products.

Chemical Structure

The chloroprene monomer (2-chlorobutadiene-1,3) has the formula CH₂=CCl–CH=CH₂. The main structural unit of the polymer is [–CH₂–CCl=CH—CH₂–]n. The presence of a chlorine atom attached to the carbon backbone imparts polarity to the molecular chain. Polar polymers exhibit better compatibility and, consequently, high resistance to non-polar solvents such as oils, gasoline and fats. The structure is dominated by 1,4-additions with a small proportion of 1,2- and 3,4-additions that affect crystallisation and elasticity.

Production Technology

CR production is based on emulsion polymerisation of the chloroprene monomer. The monomer is emulsified in water using surfactants, after which an initiator is introduced. The process takes place in an aqueous medium to control heat release and prevent undesirable side reactions. Historically, the chloroprene monomer was obtained from acetylene and hydrogen chloride with a cuprous chloride catalyst. Currently, it is produced from butadiene and chlorine followed by sodium hydroxide treatment. Polymerisation is carried out by a radical mechanism in aqueous emulsion at temperatures of 10–45 °C.

Physical, Mechanical and Chemical Properties

Chloroprene rubber possesses a unique set of properties:

Density. The density of CR is 1.20–1.24 g/cm³.

Temperature Range. Chloroprene rubber can be used at temperatures from –55 °C to +90 °C, although the actual temperature range depends on the specific chemical composition of the material. Other sources cite an operating range of –40 °C to +120 °C.

Flame Resistance. Thanks to the chlorine content in the main chain, CR is flame-retardant and self-extinguishing.

Oil and Solvent Resistance. CR has moderate fuel and oil resistance, as well as good resistance to ozone, weathering and chemical reagents. The material is not recommended for exposure to strong oxidising acids, esters, ketones, chlorinated aromatic and nitro hydrocarbons.

Mechanical Strength. CR has good mechanical properties, second only to natural rubber in fatigue and tear resistance. Hardness ranges from 40 to 90 Shore A, tensile strength from 500 to 3,000 PSI, and elongation from 100% to 800%.

Ozone Resistance. CR has high ozone resistance, which distinguishes it favourably from many other elastomers.

Crystallisation. Chloroprene rubbers tend to crystallise, with the rate depending on the grade and modifier type.

Advantages and Disadvantages

Key Advantages:

• Flame retardancy and self-extinguishing properties

• High ozone and weather resistance

• Good resistance to oils, gasoline and fats

• Wide operating temperature range

• Good mechanical properties

• Excellent adhesion to fabrics and metals

Main Disadvantages:

• Limited resistance to strong oxidising acids, ketones and esters

• Tendency to crystallise at low temperatures

• Higher cost compared to general-purpose rubbers

• Limited market availability

Grades and Classification

Chloroprene rubbers are divided into several main types depending on the regulator-modifier used:

• Sulfur-modified — regulated by sulfur and thiuram, offering increased cohesive strength and good adhesion.

• Mercaptan-modified — regulated by dodecyl mercaptan, offering improved ageing and storage stability.

• Xanthogen-modified — regulated by xanthates, offering reduced elasticity and improved adhesion to fabrics.

Main trade names include DuPont Neoprene (W, G, T series), Lanxess Baypren, Denka Chloroprene (M, A), Tosoh SKYPRENE, as well as Chinese grades CR232, CR244, CR322.

Applications

Chloroprene rubber finds wide application in various industries:

Cable Industry. Insulation and jacketing of wires and cables, including fire-resistant cables.

Automotive Industry. Production of belts, hoses, motor mounts, CV boots, braking and steering system components.

Construction. Production of window sealing profiles, sealants, roofing membranes, weather-resistant gaskets and expansion joint materials.

Rubber Technical Products. Production of V-belts, moulded and non-moulded products, hoses, belts, gaskets and sports goods.

Adhesives and Sealants. Polychloroprene adhesives are particularly widespread in footwear production, used in solution form.

Chemical Industry. Manufacture of products requiring ozone, gasoline-oil, weather and fire resistance.

Medical Products. Production of orthopaedic braces (wrist, knee), medical gloves.

Electronics. Laptop sleeves, insulating materials.

Global Market

The global chloroprene rubber market shows steady growth. In 2025, the market was valued at USD 1.23–1.78 billion. It is projected to grow to USD 1.62–2.26 billion by 2031 at a CAGR of 3.7–4.8%.

The Asia-Pacific region dominates the market with a 48.34% share in 2025, with a projected growth of 5.22% per year. Japan is the largest market with a share of about 40%, followed by Europe and North America with a combined share of about 45%.

Key players in the global market include DENKA, ARLANXEO, COG, Tosoh Corporation, Shanna Synthetic Rubber. The top 5 producers control about 75% of the market.

The main market growth drivers include: vehicle electrification (battery cooling system seals, high-voltage cable jackets, fire-barrier components); growth in infrastructure projects (weather-resistant gaskets, bearings, expansion joint materials); modernisation of electrical grids and cable systems.

Conclusion

Chloroprene rubber (neoprene) is a unique synthetic elastomer combining flame resistance, ozone resistance, oil resistance and a wide operating temperature range. Thanks to these properties, it finds application in the cable industry, automotive, construction, rubber technical products and adhesives. Despite its higher cost compared to general-purpose rubbers, chloroprene rubber remains an indispensable material in demanding applications requiring enhanced performance characteristics. Growing demand for electric vehicles, infrastructure projects and waterborne adhesives ensures sustainable growth of the CR market in the long term.