Argotec Inc. is investing several million dollars into growth for thermoplastic polyurethane and other specialty films.
The firm recently completed a 10,000-square-foot warehouse in Greenfield, Mass., where it is headquartered and runs its two plants. By the first quarter of 2006, it will start a new line dedicated to thin films made of aliphatic TPUs. The line will be enclosed in its own hard-wall clean room, said Paul Darby, vice president of sales and marketing, in a recent telephone interview.
Argotec is exploiting high-value properties exhibited by difficult-to-extrude TPU thin films. They are strong yet elastic, and resist abrasion, chemicals and ultraviolet light. Making them thin - about 2-10 mils in thickness - saves weight, makes them easier to conform to shapes they cover and improves clarity.
Darby cited several markets in which TPU films are making their mark.
Types with particularly good clarity are noteworthy in security applications. They bond glass to polycarbonate or acrylic sheet, glass to glass and glass to other substrates to create impact-resistant shields for banks, prisons, aircraft windows and armored vehicles.
Soft varieties of TPU films often are made with a matte finish, making it easier to vacuum laminate them into layers for impact-resistant textiles. Soft grades find use as an adhesive layer between glass and electronics in touch-screen monitors - a use that capitalizes on TPU film's high electrical-insulation values. Soft grades also show up in medical textiles used inside and outside operating rooms, said Darby.
Hard film grades can be highly transparent. With a pressure-sensitive adhesive applied to one film side, a hard film can be draped on a surface to protect it from abrasion, chemicals and UV light. The films are conformable, allowing them to match complex shapes such as the leading edge of airplane propellers, where the film protects the expensive props from wind-borne dust better than any paint can, according to Darby. As protective layers, TPU films typically are called on to last five years.
Argotec generally uses flat-die extrusion for its thin TPU films. It has spent years developing the technology in-house. Dave Collette, recently promoted to vice president of manufacturing and technology, said his firm is not wedded to any particular material or equipment supplier, choosing from each what best suits Argotec's needs. Low melt strength, viscosity, gauge control and the need to minimize gels are among the challenges in TPU extrusion.
Flat-die extrusion is preferred over blown film because the former provides higher quality, according to Collette. Flat-die TPU films usually have fewer unsightly gels. Flat-die extrusion avoids processing aids that can interfere with subsequent adhesive coating. As well, in-line gauge control and roll-stock surface control are easier, which is especially important for high-gloss films. For some uses, such as casting the film on a carrier like a polyethylene film, flat-die extrusion is the only real choice. TPU films on carriers are handled easily by laminators, coaters and converters.
Argotec is, however, capable of making blown film TPUs when high output rates are called for.
Chemistry choices allow Argotec to tailor film properties. Polyether-based TPU films have exceptional clarity and resist yellowing in strong light. They are water-stable and generally soft.
Polyester-based TPU films outperform polyether types in tear resistance, elasticity, tensile strength and chemical resistance. Polycaprolactone TPU combines the properties from each of those to bridge the performance gap between polyethers and polyesters.
Within each type of TPU, Argotec can choose a range of surface hardnesses. Overall they range from a low of 70 Shore A to a high of 60 Shore D.
Besides the general class of aliphatic TPUs, Argotec can make aromatic TPU films for applications where possible film yellowing is not a drawback.
TPU films account for perhaps 90 percent of Argotec's business, but the private company also works with other difficult materials like copolyester and ether-amides. Recently it added foamed TPU sheet to its slate. Its closed-cell structure and strength are opening markets in marine, seating and other areas.
Argotec's new warehouse complements its two facilities in Greenfield totaling 75,000 square feet. One of the plants already is a hard-wall clean-room environment. Officials declined to comment on annual sales and employment levels for the private, 17-year-old company.