Thermal bonding is a technique for bonding a web of fibers in which a heat or ultrasonic treatment, with or without pressure, is used to activate a heat-sensitive material, according to INDA, the association of the nonwoven fabrics industry. The material may be in the form of homofil fibers, bicomponent fibers, and fusable powders, as part of the web. The bonding may be applied all over (e.g. through or area bonding) or restricted to predetermined, discrete sites (e.g. point bonding).

There are different types of thermal bonding systems that can be used:

Calender bonding thermally bonds a web of loose fibers by passing them through the nip of a pair of calender rollers, of which one or both are heated.

Through air bonding (or air through bonding) is a bonding system that that uses high temperature air to fuse the web’s fibers. There are two basic systems: blowing hot air through the web in a conveyor oven or passing heated air through the web on a rotating drum.

Ultrasonic bonding is the use of high frequency sound to generate localized heat through vibration and cause thermoplastic fibers to bond to one another.

Thermally bonded nonwovens can be thin—going into the core of feminine care products—or high loft materials that are a few inches thick.

According to INDA, in North America there are around 55 companies making thermal bonded nonwovens and just under 200 lines. Brad Kalil, INDA’s Director of Market Intelligence & Economic Insights, says a majority of thermal bonded nonwovens in North America—about two-thirds—is going towards the transportation and the home & office furnishing sectors. Then, about 10% goes to filtration and 10% goes to absorbent hygiene.

Kalil says there’s been a fair amount of investment in thermal bond in recent years, with about 15 new lines being added between 2017 and 2021. Some of these lines, which mainly target the automotive and home/office furnishing industries, include Daesol Materials Georgia (2017), Fis Fiber Industries (2017), Marves Industries (2017, 2019), Jones Nonwovens (2018).

Meanwhile, investment in thermal bond for hygiene has been minimal as spunmelt has grown its share in this market over the last couple of decades.

“In hygiene, carded thermal bonded lost share to spunmelt many years ago as spunmelt became more uniform at lower basis weights and so had a significant cost advantage,” says Pricie Hanna, managing partner, Price Hanna Consultants. “To my knowledge, the markets for carded thermal bonded have declined to insignificance so there is no need for further investment. Many carded thermal bonded lines have been converted to carded air through bonded.”

The following is a look at some recent activity in the thermal bonding technology. We will continue to update this article as new investments and activities are announced.

• Hempitecture, a Ketchum, Idaho-based company, will soon be manufacturing a non-toxic, no-VOC and more sustainable thermal insulation product for residential and commercial buildings. Once complete, Hempitecture’s 33,000 sq. ft. nonwovens plant will be the first hemp insulation designated facility in the U.S. Hempitecture has partnered with Dell’Orco and Villani for its opening and blending line, and its high-loft airlay and thermobonding line is being furnished by Technoplants.

• TWE Group is currently building a new air-though bonding line at its site in Belgium, which was formerly owned by Libeltex, and it also continues to invest in upgrading the capabilities of existing production lines. Most recently, the company upgraded an ATB line, constructed in 2019, to handle lower material weights at super high speeds.

Hygiene, TWE’s number one market, represents about half of the company’s sales, and the company has primarily made air through bonded nonwovens for acquisition and distribution layers but topsheet and backsheet materials are driving most of the growth in the unit.

“Softness is key for the ATB top and backsheet products and this has been enhanced with natural plant-based materials,” says CCO Ralf Berens. “A new area of growth is the development of core concepts as the market is more and more moving away from the classical fluff-based solutions.”

• Fitesa, one of the world’s largest nonwovens producers, has ATB and RB carded capabilities in the main regions where it operates: Latin America (Brazil), the U.S., and Europe (Italy).  Fitesa’s carded capability is mainly focused on the hygiene market.

“The carded technology provides single conditions to blend different raw materials into fabrics with unique liquid distribution and softness properties. These connect directly with important market trends and opportunities such as sustainability (using natural or bio-based fibers) and comfort,” says Mariana Mynarski, corporate marketing, Fitesa.
Most recently, Fitesa has made investments in its capabilities in Europe.

“In the hygiene market (our expertise), carded materials will continue to face challenges competing with spunlaid fabrics due to production cost/efficiency, especially in the challenging economic scenario ahead,” Mynarski says. “Growth will be driven by sustainability attributes, product innovation, and unique technical attributes.”