Irradiation processing a corner in textiles The textile industry appears about ready to adopt ionizing irradiation as a technique to finish and cure fabrics. At least two big firms are expected to announce plans this fall to employ accelerators for grafting and cross-linking fibers to impart such features as permanent press and soil release. Identity of the companies is still confidential. But both are in about the same class as Deering Milliken, the first, and so far the only, company to routinely produce fabrics finished under the beam of beta rays (its cottonpolyester VISA). Milliken, with 20,000 employees, is slightly smaller than J. P. Stevens and Burlington Industries. Both are known to be working on irradiation processes, along with Cone Mills, Union Carbide, and FMC Corp.'s Avisco division. The story has a couple of technological plots, along with the corporate intrigue that is such a distinct feature of the textile industry. All of Milliken's competitors are trying to skirt that company's patent rights on beta irradiation, and there apparently are at least two ways of doing it. One is through irradiating the fabric at a point in the production process different from Milliken's. In Milliken's process, the fabric is irradiated at the mill, then sent to the garment maker for curing. Cone Mills, for one, is studying a technique developed by Henry A. Rutherford and William K. Walsh at North Carolina State University whereby the garment maker would do the irradiating. The other maneuver around Milliken is more chemical. Milliken's patents were the talk of the industry for their chemical completeness in covering what was thought to be all possible monomers that under irradiation would graft, by reactions involving free radicals, to the fiber. Milliken, it turns out, may not have been all that complete. If Cone Mills is successful with its process and can persuade garment makers to install electron accelerators in place of their curing ovens, the change will constitute one of the biggest revolutions in the textile industry. Traditionally, application of new technology has been left to the mills; that is, to the finishing plants. These firms add their chemicals to the fabrics and issue baking instructions to the cutters. The fabrics then go into ovens for processing that consumes heat, moisture, and manpower. During this processing the fabrics also emit odors. Irradiation would end all that. For irradiation is fast, neat,
easily controlled, and can be done at room temperature. Milliken, which is not leasing its irradiation process, says, however, that garment makers would balk at changing such ingrained habits. VISA, the company says, is already cleanly cured by the cutters. But the accelerator companies say the shift would be painless. All that's holding it back is attitude. The chemical battle of wits, however, claims most of the intrigue. Was Milliken really all that complete in covering all possible monomers that would graft to the fiber under irradiation? "Phooey," says one technical man to Milliken's claim. "The mistake Milliken made," he says, "is that they were working with old, conventional chemicals—the kind now being used in curing ovens. Or they looked at variations of these. What are needed, and what are being developed, are completely new off-
spring. That is, chemicals designed for irradiation curing." About the only chemical now known to work well in irradiation grafting is N-methylol acrylamide. NMA's special qualities were first reported by Walsh and Rutherford at North Carolina State. Du Pont and Milliken also were in on the early work. Milliken is using NMA routinely to impart durable press properties to its fabrics, but it may also be using alternative chemicals covered in its patents. In its process, the company irradiates the NMAtreated fabric to achieve grafting, then passes the fabric on to the garment maker for cross-linking through curing. The result is durable press. (See diagrams of irradiation processing.) Dr. Rutherford once reported that NMA has one significant drawback. It yellows the fabric by picking up chlorine. Milliken, however, denies that this happens. "We have had
Two routes to durable press fabrics— North Carolina State-Cone Miifs procésê (nuiyet in production)
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