Caprolactam is an intermediate primarily used in the production of nylon 6 fibres and resins. Around 68% of caprolactam is consumed in the production of nylon fibres for textile, carpet and industrial yarns with the rest used in engineering resins and films.
Nylon 6 textile fibres are easy to dye to give deep and bright shades while offering high strength and light weight. They can be combined with elastane/spandex fibres to give good stretch-fit properties. Applications are wide such as apparel, sportswear, swimwear, casual and fashion wear, and hosiery. 
Carpets and rugs made from nylon 6 are available in a large number of styles, structures, colours and patterns. They offer good wear and abrasion properties,
are resistant to staining and easy to clean. The fibres can also be recycled back to caprolactam.
Heavy duty bias tyres for truck and bus, industrial, off-the-road and agricultural applications use nylon 6 tyre cords. Nylon 6 offers strong and durable properties and high fatigue resistance making it suitable for vehicles carrying heavy loads over bad roads. It has other industrial fibre uses such as fishing lines, ropes, nets and tarpaulins.
In the US, textiles such as sportswear, leisure wear and hosiery account for 47% of fibre applications; carpets for 30%; and industrial yarns for 23%.
Nylon 6 resins are increasingly used as engineering plastics due to a combination of high stiffness and strength at elevated temperatures with toughness at low temperatures, resulting in high fatigue resistance and good welding behaviour. They are increasingly replacing metal in automotive applications such air intake manifolds. Their resistance to oils and greases has led to their use in engine covers, gears and bearings.
Packaging films manufactured from nylon 6 have a good combination of mechanical, optical and barrier properties. In particular, they provide good barrier resistance to water vapour and oxygen to extend the shelf life of products. Applications include food packaging, agricultural film and medical packaging.
Small amounts of caprolactam are also used in cross-linking for polyurethanes and in the synthesis of lysine.
The nylon 6 fibres market is mature and has been in decline in the western world at the expense of growth in Asia. The fibres sector has also seen competition from other materials such as nylon 6,6 and polyester. As a result, nylon 6 fibres are expected to only grow at 1%/year globally.
However, the engineering resin sector is much more buoyant, especially as automotive manufacturers try to reduce the weight of vehicles by replacing metals with plastics. Growth for nylon 6 engineering resins is much more robust up to 5%/year.
Overall long-term growth for caprolactam is estimated by consultants to be around 3%/year. Growth in Europe and North America will be slow-to-stagnant but it will be much stronger in Asia, particularly China where growth rates of 7-8%/year are forecast.
In Europe, consumption of caprolactam is unlikely to change as nylon textile fibre production is continuing to fall at about the same rate as engineering resin demand is growing. European textile fibre producers have steadily lost market share to lower cost Asian competitors and clothing designers, who are increasingly sourcing products in China, Taiwan, Indonesia and Vietnam.
UK-based consultant Tecnon OrbiChem puts West European demand and production during 2007 at 929,000 tonnes and 1.16m tonnes respectively, compared with 905,000 tonnes and 1.14m tonnes during 2006. East European output rose slightly, to 462,000 tonnes in 2007, from 454,000 tonnes in 2006, while demand lifted to 177,000 tonnes from 165,000 tonnes.
Caprolactam is a widely traded product with Europe one of the main exporting regions to Asia. West European exports to China, Taiwan and South Korea dipped in 2007 to 131,000 tonnes from 141,000 tonnes in the previous year, while East European exports were unchanged at 315,000 tonnes in 2006 and 2007, estimates Tecnon OrbiChem.
A major issue for European producers is the continual rise in Chinese caprolactam capacity. According to China Chemical Reporter (CCR), Chinese capacity could increase from 357,000 tonnes/year in 2006 to 770,000 tonnes by 2010.
Production of caprolactam in China was 291,000 tonnes in 2006, said CCR. Apparent consumption was 736,000 tonnes in 2006 requiring imports of 445,000 tonnes. With nylon fibre growth of 8%/year, Chinese demand for caprolactam is forecast to reach 1.04m tonnes in 2010.
Updated: May 2008. Source: ICB Chemical Profile, 12 May 2008.
Caprolactam
Process Technologies
Conventional caprolactam technology is based on the key intermediate cyclohexanone, which is usually produced by the oxidation of cyclohexane, but can also be made from phenol or toluene. Separately, hydroxylamine sulphate is manufactured by the oxidation of ammonia to nitrous oxide followed by hydrogenation in the presence of sulphuric acid. The hydroxylamine sulphate is then reacted with the cyclohexanone to produce cyclohexanone oxime. This is followed by a Beckmann rearrangement using oleum to yield caprolactam.
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