GENERAL APPLICATION

Metallized products are used in industrial, specialty and protective clothing applications. There are various ways to combine metals with textile materials for specific applications.
Metallized fabrics provide good abrasion resistance, reflectivity over extended time, wear resistance and molten metal splash resistance.

Coating/Laminating

Textile fabrics are used as substrates in metallized protective materials. Woven, knit and nonwoven fabrics may be coated or laminated with metal surfaces. Substrate fabrics can be made of aramids, carbon based fibers, PBI, glass, cotton, rayon and others. Aluminum is widely used in metallized fabrics.

In aluminized fabric, aluminum molecules are deposited on a PET film. Examples are Mylar from DuPont and Hostaphana from Hoechst. The aluminized film can reflect up to 90% of radiant heat. Gold can be used for reflection of up to 100%, but it is expensive.

Laminated metallized fabrics can be made of several layers of materials. A typical five-ply dual mirror
aluminized fabric has the following layers: aluminum, protective film, a second layer of aluminum, heat stable adhesive and fabric.

Blending

Metal sliver can be blended with synthetic or natural fibers to produce conductive textiles. Stainless steel sliver used for this purpose usually has 4.8 or 12 micron fiber diameters and weighs approximately 1.2 or 4 grams. The fiber length may vary from 1.5 to 6 inches. There are several methods to produce metal fibers including bundle drawing (most common), wire drawing, shaving, shearing, melt spinning, melt extracting and stretch casting. For maximum conductivity, the steel fiber is introduced at the last drawing operation. Protective fabrics made from metal-based blended fibres are suitable to protect individuals from the hazardous effects of electrostatic discharge and electromagnetic radiation.

Composite Yarns

Multi-filament metal fibre yarns can be twisted or wrapped with textile yarns to produce composite yarns. These yarns are suitable for cut resistant apparel items, antistatic brushes for business machines, lightning strike protection and antistatic filter bags. The most widely used metal yarns are 12 microns/91 filaments, 25 microns/91 filaments.

Nonwoven Metal Based Fabrics

Chopped metal fibres can be air or wet laid with textile fibers to form nonwoven textiles. For air layering, 1 inch fiber length and 4-38 micron fiber diameters are used. For wet layering, fiber lengths of 0.125 to 0.5 inch have been successfully used. Binders or sintering may be used for stabilization. During sintering, the organic binder fibers are burned off, leaving a 100% metallic fiber structure. In general, fiber diameters of 4-15 microns in 0.125-0.250 inch lengths are suitable for this process
Test methods and characteristics to evaluate the metallized products include the following:

• Military Specification, MIL-C-87076A, for Aluminized, Twill Weave, Aramid, Coated Cloth
• MIL-C-24924A Class I (fire proximity garments)

Applications in technical textiles:

Following Attributes of fibres make them suitable for applications in technical textiles:
• Electrical Conductivity
• Electro Magnetic Shielding
• Anti-Microbial
• Heat Resistance
• Strength
•Chemical Reactivity
• Corrosion Resistance
• Flexibility (compared to wire or steel wool textile structures)
• Weldability

Existing and Potential Applications:

Given the above product characteristics, some existing and potential applications are as follows:

Existing Applications:

1 Anti-static protective clothing garments in the Petro-chemical, pilot suits, fire workers suits, etc.
a. Anti-static fabric panels for garments
b. ESD shoe soles and Overshoes
c. Sewing threads for connection of fabric panels for improved sleeve-to-sleeve
ESD compliance.
2. Shielding fabrics for utility workers in high field areas.
3. Muscle stimulation electrodes.
4. ESD Brushes.
5. Bulk container bags for powders and pellets.