Prime opportunity with sturdy Tyvek
Tyvek has a density that is half of paper at the same thickness and size. Sidhesh Kanade finds that it can be used for printing, die-cutting, and be slit, scored and laminated.
08 Oct 2013 | 6634 Views | By Sidhesh Kanade
Invented in 1955 by Dupont, Tyvek is a high-density non-woven polyethylene which bears the property of selective barrier and is recyclable. Tyvek is light weight and strong, having features of water, chemical, termite, rodent-resistance. In the five decades since its introduction, Tyvek has been put to several versatile applications like durable documents, tags and labels, travelers and military maps, protective envelopes for postal services, car covers for UV protection, etc.
The applications have also made their way to protective clothing which include laboratory coats and aprons; and suits for mechanics and painters, for one-time use. Apart from this, Tyvek has also made its mark in the fashion industry by being used in the crafting of clothes and accessories.
Tyvek as a print substrate
Tyvek has a density that is half of the paper at the same thickness and size. It is tougher than paper in terms of tear resistance, puncture resistance, scratch and rip resistant and also bears a higher strength-to-weight ratio than paper.
Tyvek is one of the printing materials with the highest opacity. The opacity range is 90-98%. Besides high opacity, Tyvek also has good dimensional stability. The dimensions of the sheet change by less than 0.01% between a relative humidity of 0-100% at a constant temperature.
Patnaik says, “Due to the light weight, smooth surface, high dimensional stability and opacity, together with the toughness and durability, Tyvek is well suited as a printing substrate. It can be printed by offset lithography, letterpress, flexography, gravure, screen process, dot matrix, thermal transfer, ion deposition, digital press applications and inkjet processes, using standard commercial printing equipment. Spunbonded Olefin can be printed either sheet- or web-fed.”
Tyvek as a packaging material
Tyvek is a unique packaging material providing light-weight, breathable and protection from thermal excursion with high strength.
Speaking on the latest trend in the application of Tyvek, Shyam Patnaik, segment leader for Tyvek at Dupont India, emphasises its increasing usage for perishable temperature sensitive products (PTSP).
“India is a country which experiences extreme climatic fluctuations, with the temperatures soaring as high as 45 degree celsius and with rainfall of more than 150mm in some regions. With such conditions, it is essential to use appropriate packaging, which is the sole barrier in avoiding spoilage. Tyvek with its heat reflecting properties, resistance to water and breathability serves as the ideal substrate for packaging in the PTSP segment,” says Patnaik.
Illustrating via a pie-chart (fig-1), Patnaik says, “We observe that 36.3% rejections of PTSPs, the highest of all, are caused as a result of spoilage due to extreme temperatures.”
Emphasising on the cause of rejections, Patnaik adds, “Most of the perishable products are spoiled when they are packed and kept in storage, waiting to be transported. When the products are exposed to heat for a long time, they begin to perspire, which results in the release of ethylene and carbon dioxide. This activates metabolism in such products, which in turn reduces the shelf life. ”
Tyvek absorbs little or no moisture and the liquid simply runs off its smooth surface as it is made from high-density polyethylene fibres. Being a non-woven fabric, it also enables scattering of light, posing less operational hazards during handling.
“When an electromagnetic radiation wave of multiple wavelengths, such as sunlight, falls on a packaged product, there can be three types of interactions. Either the wavelength would be absorbed and converted to heat, or the wavelength would be reflected or it would be transmitted through the object. When perishables are packed in Tyvek, which reflects 98% of the solar spectrum, it helps to keep away the heat and thus avoid perishability and enhances the shelf life,” says Patnaik.
With an example of a leading pharmaceutical company in India(fig-2), Patnaik observes the journey of a PTSP from its production to its delivery to the final destination, with once the PTSP being transported is wrapped in Tyvek as compared to when wrapped in traditional stretch wrap. “The observation illustrates that thermal fluctuation of PTSP wrapped in Tyvek was much lesser as compared to the one wrapped in stretch wrap film or no cover in the ambient condition. Thus Tyvek can be used as a better alternative in the transportations of PTSP’s, to prevent thermal excursion and thus ensuring longer life to PTSP products during transportation” concludes Patnaik.