Infrared heat increases productivity of flameproof textiles

11 May '09

3 min read

High-quality home textiles for curtains, armchairs and sofas should not only look decorative, they also have to be hard-wearing and flameproof. Textiles usually get flame-retardant by a coating with special chemicals or saline solutions.

By retrofitting a new, Heraeus medium wave infrared system at their South Ockenden factory, Essex Flameproofing have been able to treble the capacity of the drying process used in the production of fire retarding upholstery and curtains. At the same time, they have also significantly reduced energy consumption.

Forgotten candles or a short circuit in the toaster - just at home it can burn fast if one does not pay attention. Curtains and home textiles should not contribute to the spreading of a fire and therefore they have to be equipped with flame-retardant properties.

Essex Flameproofing is a long-established company which works with designers and specifiers, fabric manufacturers, major retailers and upholsterers to impart fire-retarding properties to furniture and fittings. This is achieved by treating the fabric of the upholstery or curtains with flame-retardant chemicals to comply with British and foreign standards and flame retarding regulations. The application of the relevant chemicals/coatings is a wet process and drying is, necessarily, an important production stage.

Upholstery is made fire-resistant by spraying the back of the upholstery cloth with a latex flame-retardant coating, which must then be dried. Previously this was achieved by heating the coated upholstery web with a long wave infrared system. However, to meet increasing demand for the company's expertise, it was decided to investigate ways of speeding up the drying process.

As a result, a new Heraeus medium wave infrared system was retrofitted at the Ockenden factory. This consists of an aluminium framework, which houses 21, 4.5kW emitters, which are arranged to be switched on and off in seven banks of three emitters, to match the heating profile to the product to be dried. Such has been the success of the new system, which is ready to run within one minute of switch-on, that coated upholstery fabric can be dried in a single pass whereas three passes were often required with the previous system. This is partly due to the efficiency of medium wave infrared in water removal, as radiation at medium wave frequency is readily absorbed by water molecules and the energy is rapidly converted into heat.

The new system also finds further employment when it is used to provide extra capacity to dry treated curtains. Curtains are made fire-retardant by spraying them with a salt-based solution, which soaks into the fibres. When curtains come Scotch guarded, or when fabrics have low permeability, the uptake of the solution needs to be assisted by passing the wetted curtain through nip rollers. Normally, curtains are dried on their own line, but when there is capacity on the new Heraeus system, they are passed through for drying, again at twice to three times the speed.

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