Flame retardant fabrics from Pincroft
Flame-retardant clothing is essential in many industries to protect workers from sparks and splashes and legislation demands the use of top quality materials. A producer of treated fabrics used in this kind of workwear is Pincroft Dyeing & Printing, based in North West England.
Ever stricter safety requirements have strengthened the need for flame-retardant workware, says Roger Bellfield, Technical Director of Carrington Career & Workwear, which is part of the Pincroft group. Pincroft finishes fabrics to comply with the two key standards in the field, explains Bellfield: EN531, which covers general industrial workers, and EN470 part 1, for welding and allied trades such as foundry workers.
Pincroft’s lines include technical flame-retardant and insulating fabrics under the Flamemaster and Proban brand names. These start out as normal cotton and cotton polyester fabrics and gain their protective qualities through treatment with Rhodia’s Proban system. After colouring, treating and finishing, the fabrics are sold on to garment manufacturers.
“Proban is the most effective system for the treatment of apparel,” says Bellfield.
It was first launched almost 50 years ago, but research and development has continued to improve the quality of the treated product. One of the benefits is that today’s flame-retardant fabrics handle better than those of old.
“The treated fabric has changed from being fairly stiff to soft,” he says. This broadens the potential market, allowing a wide range of lighter weight treated garments to be worn in comfort. According to Bellfield, the fabrics are ideal for areas where workers are exposed to heat or flames. Typical uses are in welding and shipbuilding as they can resist sparks and molten metal splashes. Another popular application is in the electricity supply sector, as they can withstand electric arc flashes.
Firemen are often issued with uniforms impregnated with Proban, though it would not be used in the thick outer uniforms they wear when out on a call. These are made from inherently flameproof materials such as Du Pont’s Nomex – also worn by racing drivers.
Flame-retardant finishing follows on from the normal fabric finishing process. Rolls of loomstate fabric arrive at the
Next step is to add the flame-retardant treatment. This involves impregnating the fabric with chemicals using Rhodia’s patented system. Proban chemicals are padded on, then dried off though a Monforts stenter and cured in ammonia gas in Rhodia-designed equipment. It takes just a few minutes to convert the chemical from a monomer to a polymer embedded within the fabric’s fibres. A meticulous washing-off process follows, to neutralise the chemicals, and remove all traces of ammonia, explains Bellfield.The polymer formation process is irreversible, with the Proban fully impregnated into the fabric – rather than simply being coated on. It is inert, completely insoluble and cannot be removed by washing.
The equipment is cost-effective to run, says Bellfield. The ammonia gas part of the process runs at atmospheric temperatures. Full heat exchange equipment is however used in the stenter and dyeing stages. Koenig equipment recovers heat from the drying and thermosol machinery. In addition, Pincroft's finishing stenters have scrubbers and Koenig ionisers to prevent smells and fumes from exiting into the atmosphere. “Obviously this is of major benefit environmentally and provides for energy savings amounting to some 30%,” says Bellfield.
Fabric finishing is now far more efficient than with the similar, but older, machinery that Pincroft has replaced in recent years. Production of technical textiles such as these has an additional burden compared to other types of fabrics. Production quality control has to be very high, explains Bellfield, given that lives could be at risk otherwise. Effectiveness of the treatment cannot be determined visually – the treated fabric looks and feels just the same as an untreated one. The simple but effective means of testing is to apply a gas flame test to a sample from every batch.
Rhodia also checks to ensure that quality is of the highest order. Proban is sold on a licensee-only basis and textile companies have to demonstrate that they have the necessary skills in order to obtain a licence. Only then does Rhodia supply the technology, chemicals, training and ongoing technical support. Licencees also have to submit samples on a regular basis, providing further corroboration of the quality and protection.
