Nonwovens: Current Trends & Opportunities

The future of nonwovens promises to be interesting and potentially very rewarding.

By Dr. Behnam Pourdeyhimi, Technical Editor

While the nonwoven and textile industries share some common heritage, the nonwoven industry has grown to present a broad array of engineered-fiber and polymer-based products that are driven by high-speed, low-cost, innovative, value-added processes. The nonwoven industry created an ecosystem that is built on automation, reducing the dependence on low cost labor — hence, the industry has not had to set up manufacturing facilities in low-labor cost regions in the world. Nonwovens are typically made and converted where they are sold thereby minimizing shipping costs.

The industry has adapted technologies from the pulp and paper, and extrusion industries, for example, to create the desired products at reasonable cost. Automated converting has been a major part of the nonwoven supply chain for many years, and today, the industry can produce in excess of 1,000 diapers per minute.

Clearly, high speed, large volume and low unit cost of production demands full automation. This in turn, means that short runs and flexibility in offerings becomes limited.

Today’s nonwoven segments of the industry include raw material suppliers, roll goods producers, the converters/fabricators of the end use products, a machinery industry supporting the previous three categories, auxiliary material suppliers, winding, slitting, packaging equipment makers, among other segments. This list does not offer as clear a picture as one might imagine, because the picture is further clouded by varying degrees of vertical and horizontal integration within the industry. Globally, the picture is further complicated by the local market and economic nuances.

What is clear however, is that the nonwovens industry continues to be adaptive, creative and relentlessly opportunistic. This means that in the immediate years to come, there may be an array of products that can replace more traditional textiles — some may see this an opportunity, while others may see this as a threat.

Sustainability

While a move to sustainable production is partly driven by regulations and taxation, the nonwoven industry has always been at the forefront leading the charge for sustainability. At ITMA 2015, sustainability was one of the major themes that dominated some of the educational sessions, discussions and awards. The topic also was evident in the themes presented by a number of key manufacturers. Almost entirely, the nonwovens exhibitors at ITMA 2015 had some degree of focus on sustainability.

Words like sustainability, recycle, reduce and reuse, are more than buzzwords in the nonwovens world, they are real. Add to these words also reinvent. Given macro-trends globally, reinvention of existing products and processes is more real than ever.

In January 2018, the European Commission adopted the world’s first comprehensive Plastics Strategy. In May, the commission released “The Single-Use Plastics: New Measures to Reduce Marine Litter” report, which proposed new rules to reduce the 10 most found plastic waste items on Europe’s beaches that account for 43 percent of total marine litter. The 10 items are:

1. Cotton buds;
2. Cutlery, plates, straws and stirrers;
3. Sticks for balloons and balloons;
4. Food containers;
5. Beverage cups;
6. Beverage containers;
7. Cigarette butts;
8. Plastic carrier bags;
9. Crisp packets and candy wrappers; and
10. Wet wipes and sanitary items.

The actions recommended to reduce this waste includes:

• Ban — replace with sustainable alternatives;
• Education and extended producer responsibility (EPR);
• Reduction of use;
• Increased recycling efforts;
• New labeling to encourage proper disposal; and
• Redesign.

This ban on single-use plastics has already impacted the nonwoven industry. Item 10 on the list, the nonwoven wet wipes and sanitary items, were subjected to EPR. This is a policy approach that extends the producer’s responsibility for a product beyond the current scope — for worker health and safety, consumer safety and production costs — to also include management of product after the product has been used by consumers. EPR policies generally shift the waste management cost or physical collection partially or fully from local governments to producers. Policies can also involve incentives for producers to take environmental considerations into account when designing their products.

EPR was first pioneered in Europe more than 20 years ago. Since then, the vast majority of European Union Member States have introduced EPR for packaging.

EPR is not an option for such products as baby wipes and sanitary products. These products are made using a mixture of cellulose and a man-made fiber such as polyester (PET) or polypropylene (PP), and are produced mostly using carding and hydroentangling methods.

Complying with the European Union ruling requires a different solution for wet wipes and sanitary items. The nonwovens industry offers alternatives for producing sustainable wipes and other products. For example, a major innovation was offered by Austria-based Andritz AG. The high-performance Wetlace™ process for flushable, dispersible, and biodegradable wipes was showcased back in 2015. Similarly, Germany-based Trützschler Nonwovens GmbH, in collaboration with The Voith Group, Germany, offers solutions that can replace existing fossil-based polymeric fiber products with cellulose and other bio-based polymers such as polylactic acid (PLA) to overcome the EU ban.

These processes can produce wipes by combining wetlaid and hydroentanglement technologies proven to producing nonwovens and nonwoven wipes from 100-percent natural and/or renewable raw materials without chemical binders. The processes also expand the range of potential offerings allowing carbon and glass to also be processed on the same machinery.

Patterning allows producers to differentiate their products clearly with an almost unlimited number of possible patterns. An example of a 100-percent cellulose based flushable wipe featuring unique artwork is shown in Figure 1.

These wetlaid/hydroentangled processes are economically viable in that they have a much higher throughput than the current carding/hydroentangling systems they are replacing. While capital costs may be higher, the total system cost is lower because of the higher throughput and this should translate to no increase in cost to the consumer. Indeed, it may result in lower total unit cost if the volumes are large enough — and for the markets of interest, they indeed are.

Another major area of focus is reuse. There is significant industry activity around zero waste as well as recycling. This is a real challenge for industries such as the nonwovens industry where large volume production also means large volume edge trim and other waste. Reuse will be a major area of focus for many companies. Activities will focus on finding new applications for such waste or complete reuse of the same product. The challenge will be with mixed materials and also bicomponent fiber recycling/reuse. New approaches, new compatibilizers and new chemistries will be needed to recycle mixed materials.

There will be also much more significant focus on the use of biopolymers such as PLA, polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), and their blends, and when possible, cellulose fibers. It’s likely that a generation of new products will replace the existing state-of-the-art. One key is that these new materials have to also be economically sustainable — today, the industry has many sustainable solutions that are not yet economically sustainable and that will remain a challenge unless regulations and taxation outweigh the material costs. In the more niche markets, these new bio-friendly products will appear first, as was seen with the PLA-based coffee/tea filters and single-use coffee pods.

From Disposable To Reusable

There are several drivers that will lead to the use of nonwovens in traditional textile products. These are:

• The recent advances in printing technology. This may lead to the replacement of multicolored woven fabrics made using multicolored yarns with simple woven fabrics that can be printed to mimic the finer structures. These products may result in significant savings because of the ability to do short runs and offer mass-customization like never before. The right kind of nonwoven structure would be an ideal candidate for such printed materials.
• The need for controlling costs, while offering unique fabrics that offer the right kind of performance. This is where nonwovens will excel. Imagine for example, a structure that can utilize polyethylene (PE) to provide a cool touch on one side, with PET on the other surface that offers a warm touch. PE fibers available today such as Dyneema and Spectra, are all high performance and very expensive. A bicomponent spunbond can easily be made using materials that are not used today in the textile industry offering performance and differentiation at lower cost if the volumes are justified. A printed nonwoven can replace many traditional structures. One correctly sized piece of nonwoven machinery can replace hundreds of looms and offer savings in capital costs, power consumption and lower carbon foot prints. The time is right. But, are such structures available today?

Durable Products

The meaning of the word durable, a popular word at the current time, is not always clear. Nonwovens can be long-lasting or have a short lifecycle. Most nonwovens are engineered to be single-use products, and function adequately for the applications for which they’re designed. Products such as automotive nonwovens and geosynthetic nonwovens are intended to last for a long time, and are often called durable. The nonwoven industry prefers to refer to these longer lasting products as long-life nonwovens, rather than durable products.

The industry also has multi-use nonwovens. For example, many commercial wipes used in Europe today are multi-use — that is, they can be used to wipe a surface, then be washed, rinsed and cleaned to be reused many times over.

From the perspective of functional clothing, materials need to withstand multiple launderings without loss of functionality or appearance. There is a distinction here: Long-life nonwovens are not necessarily washable, although they can function for a very long time. Durable, washable nonwovens are a different class altogether, and there are not too many such products on the market … yet. Watch out for functional nonwovens products in technical clothing applications because these will emerge a lot sooner than many imagine. The technology of choice will depend on the assets in place, the applications, and the functions required, among other factors. However, spunbond hydroentangled structures will be optimal for such applications because of their strength, durability and flexibility in the choice of materials. Polymer to fabric allows the use of polymers that are not commonly used, and this can lead to performance attributes that would differentiate these structures from the pack.

Historically, there have been two major efforts in forming durable fabrics. PGI Nonwovens, now part of Evansville, Ind.-based Berry Global Inc., introduced the line of Miratec® fabrics not so long ago. These staple-fiber-based products were carded and hydroentangled with additional chemical bonding. The hydroentangling was performed using PGI’s unique Apex® technology that could create textures and structures equivalent to any textiles. Miratec featured blends of fibers and could perform equal or better than its woven counterparts. Most of these fabrics contained additional binders to ensure that the fabrics would not un-entangle during laundering. Consequently, these fabrics did not have the hand or drape required for most uses, and consequently, their use remained limited.

The other durable nonwovens effort was by Germany-based Freudenberg Group utilizing the bicomponent spunbond technology coupled with hydroentangling.¹ Spunbond bicomponent extrusion technology involves spinning continuous filaments composed of two polymers that are deposited onto a forming belt and bonded either mechanically, thermally or chemically. Fine fiber spunbond process often is only capable of producing fibers larger than 10 to 15 microns. The key to this technology will be forming a structure composed of smaller fibers than usual and that only means that exotic fiber types will be needed for these applications. One of the key patents in this area is held by Freudenberg (Robert Groten, et al), which details the process for splitting segmented pie fibers in a continuous process using hydroentangling — a process that uses high pressure water-jet curtains to mechanically move, wrap and entangle fibers.² During the process, the water jets split the bicomponent segments resulting in two different, wedge-shaped fibers (See Figure 2). The term splittable refers to bicomponent fibers that have one single common interface and where the two components are exposed to air on the surface of the fibers. Classical examples of splittable fibers include segmented pie (see Figure 3), segmented ribbon and side-by-side. Mechanical splitting requires the fiber components to have little affinity to one another; therefore, the selection of polymers and polymer ratios plays a key role in the ability to split and quality of the split fiber.³

Freudenberg’s fabric was marketed as Evolon® — originally a 16 segmented pie — and is the first commercially available spunbond reusable, durable microdenier fabric. The latest version of Evolon, a 32 segmented pie, is an amazing structure that provides a smooth uniform surface ideal for printing applications.

The fiber size after splitting is dependent on the diameter of the original fiber, the number of segments and the spinning parameters. There are a few limitations to the segmented pie structure. However, wedged shaped fibers formed during the splitting tend to pack densely, and often this may lead to low tear resistance. A hybrid structure composed of two or more bicomponent fibers can lead to more permeability and higher tear resistance. One such structure is the Madeline durable nonwoven produced by Turkey-based Mogul Co. Ltd.

Spunbond microfibers are also formed by removing one of the components in a bicomponent structure using caustic and other solvents. The most common cross section used is the islands-in-the-sea where the sea is removed leaving the islands behind. As the number of islands increases, the size of the resulting fibers decreases. Because this method requires the removal of a component there are often environmental concerns along with additional costs because of the removal process and waste of the sea polymer. Additionally, the challenge with these structures is that the islands tend to stay bundled.

Microfiber nonwovens are used in suede and leather products, durable wipes and automotive components such as headliners, but have made little headway in durable, washable, technical clothing applications. This is partly because microdenier fabrics thus far have lacked adequate drape and stretch, and are difficult to dye — they cannot produce deep shades.

Emerging Durable Nonwoven Fabrics

There have been a number of attempts to overcome the shortcomings of the existing micro-denier and staple fiber durable nonwovens, which have resulted in a number of new developments. Below, is a glimpse into the future and what some new technologies may offer in a durable nonwoven structure.

Structures With Super Moisture Transport. Products such as Coolmax®, 4DG, and other structures use fiber shape as a means to create capillarity for rapid moisture transport.

Coolmax® is essentially a flat fiber with a superior surface finish to allow the transport of moisture. Because of its shape, it also packs differently compared to round fibers leading to more capillarity.

4DG (Deep Grooved) fiber originally developed by Eastman Chemical Co., Kingsport, Tenn., and Cincinnati-based Procter & Gamble Company (P&G), is formed by controlling the shape of the spinnerets and consequently, fibers are normally larger than what is commonly used in apparel, and not ideal for technical clothing applications unless used in a blended structure.

A new, emerging structure is known as the winged fiber or nano-channel fiber (See Figure 4).⁴ While it was originally created for use in a spunbond nonwoven, the filaments or even the staple fibers can easily be utilized in critical applications where Coolmax and other similar structures are used. Here, the filaments are formed as a bicomponent fiber where the winged component is wrapped by a sacrificial sheath much the same as islands in the sea. The shape is controlled through the spinpack design and not the spinneret.

Consequently, fibers as little as 1 denier or less are possible and with a density of less than 0.7 grams per cubic centimeter, these fibers can be light, offer warmth and moisture management like no other fiber. With this technology, the fibers are formed into the final product and a finishing step removes the sacrificial sheath to release the winged fibers. The fibers do not inter-digitate, but stay apart resulting in higher permeability and capillarity. The fibers can reach a specific surface area of 20 square meters per gram (m2/g) as compared with 0.2 m2/g for a round fiber of the same size.

The nonwovens structure made using winged fibers is durable, drapable and will be an interesting component in activewear (See Figure 5). Whether as a knitted fabric, woven or nonwoven, the high surface area will translate to much faster wicking and therefore, for next-to-skin applications requiring moisture management, this structure can offer unrivaled performance.

Note that structures made with fibers such as the winged fiber also can be used to form durable wipes, filters, and suede and leather products.

High Strength Micro and Nanofiber Structures. Nonwovens are not necessarily known for their strength because they tend to be associated with disposable products. However, high-performance nonwovens are used to stabilize structures such as roads and embankments, although they are often heavy and not necessarily drapable.

It was recently discovered that through mechanical actions — shearing and hydroentangling — islands-in-the-sea fibers can be fibrillated (See Figure 6).^5-6 If the sea component is fractured and fibrillated, the sea remains in the structure not only making the process more economical and environmentally friendly, but the fractured/fibrillated sea elements wrap the fibers and can act as a binder when and if melted.⁷

This allows the formation of structures composed of sub-micron fibers that are superior in terms of tear and tensile strength and abrasion properties, and offers properties not easily achievable.⁸ As a coated substrate, they can be formed into shelters, tents and awnings.⁹ Figure 7 shows a full-size tent recently delivered to Tyndel Air Force Base.

High-speed textile printing is going to be a game-changer for the traditional textile industry and also the nonwoven industry. The reduction in SKUs and the ability to do mass-customization and on-demand printing will change the textile industry as we know it. Durable nonwovens will also likely find a home in the more traditional areas of textiles where printed durable nonwovens will replace many of the textiles as we know them. The new generation of Evolon, the Madeline fabric and the new emerging fabric structures utilizing the winged fiber or fibrillated islands-in-the-sea demonstrated by The Nonwovens Institute, Raleigh, N.C., will be game-changers in this regard.

Macro trends in sustainability will drive major new product and process innovations in nonwovens. Also, new developments in durable nonwovens may emerge as the next generation of technical textiles for many critical applications. These structures are also strong, and possess significantly higher surface area than existing fabrics that will enable functionalities that are not available today.

Note that some of the developments may also impact wovens and knits because the fiber technologies developed for new nonwovens can readily be spun into filaments and staple fiber that can be used to make woven and knitted fabrics, forming the basis for the next generation of technical clothing fabrics.

The emerging nonwovens however, will not be your father’s nonwoven, and will be different from nonwovens in use today. The future of nonwovens promises to be interesting and potentially very rewarding. The IDEA show in March will highlight some of these new innovations.

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References:

¹ Groten, R., Grissett, G. “Advances made in Micro-Denier Durable Nonwovens”, Presented at TechTextil, March 29, 2006, Atlanta, Georgia, U.S.A.

² Nakajima, T, Advanced Fiber Science, Woodhead publishing Limited, 1992, pp 108-109.

³ Durany A, Anantharamaiah N, Pourdeyhimi B, “Micro and nanofiber nonwovens produced by means of fibrillating/fracturing Islands-in-the-Sea fibers”(2009) J Mater Sci 44(21 ):5926

⁴ High Surface Area Fiber and Textiles Made from the Same, US Patent 8,129,019

⁵ Nagendra, A., Verenich, S., Pourdeyhimi, B., Durable Nonwoven Fabrics via Fracturing Bicomponent Islands-in-the-Sea Filaments. JEFF, Volume 3, Issue 3, 2008

⁶ Fedorova, N; “Investigation of the utility of islands-in-the-sea bicomponent fiber technology in the spunbond process”, (2007) Dissertation, Fiber and Polymer Science, North Carolina State University

⁷ Micro and Nano-Fiber Fabrics by Fibrillating Islands in the Sea Fibers, US Patents 7,981,226 and 8,420,556

⁸ High Strength, Durable Fabrics Produced by Fibrillating Multilobal Fibers, US Patent 7,883,772

⁹ Fedorova, N; Pourdeyhimi, B. High Strength Nylon Micro- and Nanofiber Based Nonwovens via Spunbonding, Journal of Applied Polymer Science, 2007, Vol. 104, 3434

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February 20, 2019