Survey of Chemical Substances in Consumer Products, No. 63 2005 – Mapping and release of chemical substances from products made of chloroprene

Mapping and release of chemical substances from products made of chloroprene

1 Introduction

Chloroprene rubber is used in products such as boots, waders, surf and dive suits, gloves, socks and similar products for leisure activities. Neoprene is also used as a synonym for chloroprene. Neoprene is the raw material company of DuPont Dow Elastomers' trade mark for chloroprene (polychloroprene). The Danish consumption of chloroprene rubber for consumer products is unknown; however, on a global basis the consumption of chloroprene is estimated at approx. ½ million tons per year (IDA). The products can smell very strongly of "chemistry". Some chloroprene products are worn tightly against large surfaces of the skin. Consequently, there is a risk that volatile substances in chloroprene may be inhaled by the user or absorbed by the skin.

Chloroprene rubber in finished products is vulcanised using zinc oxide. A complicated, chemical process occurring during vulcanisation of chloroprene rubber forms cross links between the rubber chain molecules that improve the elasticity of the rubber, remove its adhesiveness and make the rubber dimensionally stable. The chloroprene monomer differs from the

isoprene monomer, which is the building stone in natural rubber, in that a methyl group is exchanged with a chlorine atom. This means that chloroprene rubber is far more weather resistant than natural rubber and that its resistance to oil, petrol and chemicals is also good. For most chloroprene products, this involves either fabric-reinforced or fabric-covered types. Nylon or polyester is typically used as fabric. For suits, gloves, supports, etc. based on chloroprene, the rubber is also constructed of closed cells to obtain good product insulation properties.

On a global basis, raw polychloroprene rubber is manufactured by a total of five raw material suppliers: DuPont (Neoprene), Bayer (Baypren), Enichem (Butachlor), Denka Kagaku (Denka) and Tosoh (Skyprene). According to according to the literature (John S. Dicks, p. 133), DuPont accounts for more than 75% of the chloroprene production capacity. The raw material suppliers also produce several chloroprene rubber variants to provide the finished products with special properties. Special attention is paid to the ability of chloroprene to crystallise making the material rigid and inflexible. Thus, sulphur-modified polychloroprene types with improved storage and in-use properties are manufactured since they crystallise slowly. There are also mercaptan-modified types which crystallise either quickly or very slowly. Polychloroprene is also available as a copolymer with methacrylic acid in the form of latex. This variant is used for example to produce rubber gloves.