Taro Olivo, Associate Editor10.30.23
As consumers continue to demand improved levels of noise control in many areas of their lives, nonwovens are fitting the bill. The ability of nonwovens to offer a lightweight substrate with exceptional sound absorption continue to win them a role as acoustic materials in automotive, construction, interior design and other applications. And, nonwovens producers are optimistic about the future of nonwovens in this role as the materials continue to replace foam and other insulation materials.
Recently, Dalco and Global Felt Technologies have expanded their acoustical products into many more automotive platforms and industrial applications. In the third quarter of this year the Union, SC plant added a new, state-of-the-art needlepunch line. The companies have also added an off-line die cutting operation to custom cut their needlepunch products into items that are currently being used in hybrid wheel well liner applications, a combination of injection molding and needlepunch whereby the die-cut needlepunch supplies the acoustical portion of the wheel well liner.
For the ICE (internal combustion engine) market, Dalco/Global Felt supply acoustical needlepunch nonwovens to minimize noise from the outside world penetrating the cabin of the vehicle, which can cause an unpleasant experience for the driver and passengers. “The customary ICE engine noise, in a way, masked some of this noise,” says Gale Shipley, automotive sales manager, Dalco Nonwovens/Global Felt Technologies. “With the automotive sector’s huge push to EVs, the engine noise has been eliminated. Any outside sounds and/or any internal loud music sounds need to be mitigated with nonwovens.”
According to Shipley, Dalco and Global Felt Technologies are seeing a volume surge for these acoustical products. In some cases, the market is requiring higher weights, and in others, a more customized fiber blend to achieve the result of decreased noise propagation whether outside to inside or inside to outside, Shipley adds.
Acoustics technology is also becoming more important in workplaces and homes. “As workplace spaces become smaller, acoustical office barriers are essential to minimize outside noises from interfering in phone calls, or now, the highly used Teams’ calls,” Shipley explains. “These barriers can be commodity-like or can be very high-end designed versions.”
In living spaces, acoustical nonwovens are used in sound barriers, walls, flooring and ceiling, between apartment or condo units as well as sound mitigation from in-home theater or gaming rooms, she adds.
Meanwhile, Dalco and Global Felt Technologies are seeing new market growth for acoustical nonwovens along with some unique part names. “A great example of a growing automotive market is the frunk, which is the front trunk of an EV,” Shipley points out. “Although current trunk products can fit this niche, the linear yards/vehicle will sometimes double in volume.”
Other growing markets are nonwoven dilour carpets, anti-slip carpet backing and battery pack insulative materials. The company’s Union, SC, plant has installed a piece of equipment that manufactures the unique anti-slip backing for carpets and for automotive floor mats.
Looking ahead, the company expects to see growth in the acoustical nonwovens market, and in nonwovens in general, driven by recyclability, sustainability and climate concerns. “The versatility of nonwovens—polymers, deniers, fiber shapes, etc. - lends to sustainable growth and is only limited by the imaginations of designers, engineers, and those rare, out-of-the-box-thinking entrepreneurs,” Shipley says.
Dr. Frank Heislitz, CEO, Freudenberg Performance Materials, says the high sound absorption of the acoustic pads is achieved by the specific ratio of fine and coarse staple fibers in the support layer, as well as the design and material of the flow layer. The interaction between these two layers is also precisely tailored. The support layer developed by Freudenberg Performance Materials is not mechanically sewn in comparison to conventional market products. This lowers weight while the volume remains the same: an important consideration in extending the range of electrically driven vehicles since, for example, heat output in winter can be reduced.
“The material of the flow layer which can also function as an oscillating mass offers further advantages in terms of absorption and weight,” says Dr. Heislitz. “Given the special engineering, the inner nonwoven surface is increased, which improves absorption while keeping the weight low. The flow layer can be used to bond the support layer on one or both sides as needed.”
In the automotive segment, sustainability is driving the change to new mobility. “In this segment, lightweight construction is an important issue in automotive engineering due to governmental regulations concerning CO2 emissions on the one hand,” he explains. “On the other hand, acoustic insulation is important due to less noise in the car interior of e-cars. Freudenberg’s nonwovens can be used very efficiently in lightweight construction and through its superior acoustic properties also the passenger’s comfort in the car interior is improving.”
For applications in buildings, Freudenberg offers SoundTex, a thin acoustic nonwoven that is applied to the back of perforated structures to absorb sound. It is used extensively in a number of applications where acoustics are a prime consideration for either artistic or purely functional reasons. Typical examples include airports, office buildings, municipal halls, theaters, convention centers, subway stations, partitions and furniture in offices all over the world.
With its porous sound absorber, SoundTex converts the sound energy into thermal energy due to viscous friction. “The ultra-thin structure of our acoustic nonwoven makes handling and installation easy,” says Dr. Heislitz. “With a thickness of only 0.27 mm, it provides architects and designers with maximum flexibility by reducing shipping and storage costs at the same time.”
SoundTex can be supplied in roll or sheet form, eliminating the need for manual cutting and fitting. This feature also allows greater use of automated production processes.
“Acoustic nonwovens are air-permeable and do not interfere with certain ventilation processes,” says Dr. Heislitz. “This feature provides architects and designers with greater flexibility in positioning air inlets and vents. Even applications involving heating and cooling systems have proved to be very efficient.”
“As is common knowledge, the distinctive attributes of porous materials are highly advantageous for noise control applications,” says Selahattin Onur, R&D manager, Merkas. “Within this context, sound propagation through fibrous materials serves as the inspiration for projects to develop acoustic insulation products created through the utilization of our ATB lines.”
Initial findings revealed that the standard materials produced via Merkas’ ATB lines exhibited noteworthy sound transmission characteristics. Nevertheless, it became evident that their acoustic absorption performance did not reach the expected point. To enhance the acoustic absorption properties, Merkas modernized the process by altering the fiber orientation design integrated to the industrial ATB line. This innovation enabled to the company achieve desired characteristics of sound insulation performance from adapted structure. “Thus, for all practical purposes, the sound insulation range is created using carded air through bonding technology, coupled with a pioneering invention in fiber orientation,” Onur explains.
Since 2021, Merkas has been working on an acoustic project, called Flucpore, with applications in construction, automotive and everyday life. With Flucpore TB products, the company is focused on automotive applications. One of its key innovations involves altering the alignment of fibers to achieve a high loft and light weight. “This innovation aims to provide materials with improved acoustic properties and greater versatility,” says Guldem Yucel, R&D engineer.
Another technical advantage of the Flucpore acoustic insulation series is the unique recovery resilience of their fibers, which resembles foam. “This characteristic provides these fibers with a competitive edge, offering enhanced breathability, reusability, increased loft and a substantial product without excessive bulkiness, offering light weight with excellent sound absorption capacity,” Yucel explains.
Its production range is available from 330 gsm to 1000 gsm to meet specific application areas. This feature holds particular significance for automotive industries, Yucel adds. As part of this project, Merkas is also exploring the application of 2D embossing on an 80 gsm product to enhance its acoustic absorption properties.
Merkas’ plans for the future include expanding its TB range with already existing products named the FP 103, FP 104, FP 105 and FP TB series. Within this scope, its ultimate objective is to reduce product weight while enhancing acoustic performance. Thus, it is collaborating with suppliers and conducting trials to identify areas that require development in accordance with customer needs, both in production and application domains. “We intend to broaden our market presence by conducting experiments with leveraging the flexibility and innovative capabilities of our production lines, and we are experimenting towards creating lighter structures by using thinner raw materials and reducing the fiber diameter to achieve the greatest possible acoustic control,” Yucel says.
According to Onur, the critical domains where noise control is necessary can be categorized into four distinct groups: residential, commercial, automotive and industrial. In residential areas, it is crucial for maintaining a peaceful and comfortable living environment. This includes reducing noise from traffic, neighbors and other sources to ensure that residents can rest, work and engage in daily activities without disruptions.
“Effective acoustic design is necessary to create a productive and pleasant atmosphere. This requires minimizing echo, controlling background noise, and isolating confidential discussions,” says Onur. “Commercial spaces such as markets, hospitals, auditoriums, schools, and dining establishments require effective sound management. The architectural design of buildings and the isolation of sound sources in these locations can contribute to achieving optimal acoustic conditions.”
In industrial settings, sound generated can be intently managed through redesigning of machinery to reduce sound emissions, the physical isolation of machinery within particular chambers to contain sound, and the use of noise barriers to deflect and absorb sound waves, he adds.
Meanwhile, automobiles produce a range of acoustic transmission depending on their velocity and environmental conditions. Acoustic management in automotive aims to minimize the transmission of exterior noises originating from tire, engine and exhaust sources into the vehicle’s interior, as well as the sounds resulting from the interaction of metal and plastic components within the vehicle. “Controlling the noise inside a modern vehicle is critical for manufacturers due to interior noise currently being a competitive quality characteristic of automobiles,” says Onur. “Furthermore, the constraints on automotive noise control are associated with the material’s weight and thickness, which must be optimized to reduce the vehicle’s overall weight.”
Additionally, with the growing demand for electric vehicles, the production and sales of electric cars have surged. The battery of the car is heavier than the other parts. In response to the weight of the battery system, which constitutes the heaviest component in electric vehicles, the design of electric cars necessitates a focus on lightweight materials. This incorporation of lightweight materials helps offset the battery weight and, consequently, reduces the overall weight of electric cars, Onur adds.
To effectively address to this challenge, Merkas has developed a sound absorption range featuring a lightweight fiber network structure. The fibrillar and porous structure of the product helps to trap and dissipate sound energy, reducing reflections and controlling reverberation. Hence, this approach has the potential to result in elevated sound quality and the establishment of a more balanced acoustic environment.
Tenowo’s nonwovens used for NVH automotive applications can be used for A+B side scrims for hood liners, dash inner- and outer parts, tunnel- and underbody insulation, battery insulation pads, carpet and headliner hybrid parts, as well as beauty cover parts for E- and combustion engines in cars. “Our nonwovens are part of a sandwich construction in combination with different foams, recycled shoddy pads, mineral wool or other core materials,” explains Detlev Käppel, director, Sales Department, Tenowo. “In combination we can provide sound absorption advantages at different frequency levels at a low total weight for the finished part.”
The company’s nonwovens designed with special air flow resistance are enhanced by Tenowo’s own developed finishing/coating step in order to reach a specific air flow resistance. “[This product] helps our customers to reduce weight for its core materials and therefore can save costs by simultaneously reaching required acoustic targets by the OEM level,” he says.
Meanwhile, Tenowo’s Zetaloft+ nonwovens are used as a substitution for other acoustic core materials such as foam. The product can also be used in car seats also where it can substitute spacer fabrics.
Outside of automotive applications, requests for recyclable and sustainable materials in workplace and office areas are always discussed, Käppel says. Nonwovens, mostly thermally bonded high-loft grades like Tenowo´s Zetaloft+, can provide both recyclability and acoustic performance. “Our products are certified according to GRS (global recycled standard) which helps our customers to qualify their finished end product,” he says. “Also, end of life ‘take back’ and a full circular economy concept is the entrance for new developments.”
From Käppel’s point of view, nonwovens are the product of choice when it comes down to 100% recyclable and sustainable raw material concepts, even with fibers being produced by recycled materials, such as PET bottle flakes. “The products can outperform different kinds of core material such as foams by similar performance and cost level. Compared to other products on the market (cross laid), Zetaloft+ nonwovens consist of vertical oriented fibers which provide advantages for ‘recovery force’ and other specification parameters.”
Looking ahead, Tenowo hopes that the entire industry takes the sustainability idea seriously, as sometimes it requires more cost. “The automotive industry especially struggles sometimes to acknowledge this given fact,” he says. “The simple answer is, you can’t have all advantages, being sustainable at lower cost. All industry partners must commit to certain compromises when we want to preserve our environment and future to ensure a better life.”
Dalco Nonwovens/Global Felt Technologies
Dalco Nonwovens and Global Felt Technologies produce needlepunch nonwovens for many markets including those targeted for enhanced acoustics. Their acoustics products are used in several markets with the largest sectors in automotive and flooring, and they can be specialty engineered, utilizing various deniers of fibers and various blends of fibers to target the acoustical signature needed for a specific application.Recently, Dalco and Global Felt Technologies have expanded their acoustical products into many more automotive platforms and industrial applications. In the third quarter of this year the Union, SC plant added a new, state-of-the-art needlepunch line. The companies have also added an off-line die cutting operation to custom cut their needlepunch products into items that are currently being used in hybrid wheel well liner applications, a combination of injection molding and needlepunch whereby the die-cut needlepunch supplies the acoustical portion of the wheel well liner.
For the ICE (internal combustion engine) market, Dalco/Global Felt supply acoustical needlepunch nonwovens to minimize noise from the outside world penetrating the cabin of the vehicle, which can cause an unpleasant experience for the driver and passengers. “The customary ICE engine noise, in a way, masked some of this noise,” says Gale Shipley, automotive sales manager, Dalco Nonwovens/Global Felt Technologies. “With the automotive sector’s huge push to EVs, the engine noise has been eliminated. Any outside sounds and/or any internal loud music sounds need to be mitigated with nonwovens.”
According to Shipley, Dalco and Global Felt Technologies are seeing a volume surge for these acoustical products. In some cases, the market is requiring higher weights, and in others, a more customized fiber blend to achieve the result of decreased noise propagation whether outside to inside or inside to outside, Shipley adds.
Acoustics technology is also becoming more important in workplaces and homes. “As workplace spaces become smaller, acoustical office barriers are essential to minimize outside noises from interfering in phone calls, or now, the highly used Teams’ calls,” Shipley explains. “These barriers can be commodity-like or can be very high-end designed versions.”
In living spaces, acoustical nonwovens are used in sound barriers, walls, flooring and ceiling, between apartment or condo units as well as sound mitigation from in-home theater or gaming rooms, she adds.
Meanwhile, Dalco and Global Felt Technologies are seeing new market growth for acoustical nonwovens along with some unique part names. “A great example of a growing automotive market is the frunk, which is the front trunk of an EV,” Shipley points out. “Although current trunk products can fit this niche, the linear yards/vehicle will sometimes double in volume.”
Other growing markets are nonwoven dilour carpets, anti-slip carpet backing and battery pack insulative materials. The company’s Union, SC, plant has installed a piece of equipment that manufactures the unique anti-slip backing for carpets and for automotive floor mats.
Looking ahead, the company expects to see growth in the acoustical nonwovens market, and in nonwovens in general, driven by recyclability, sustainability and climate concerns. “The versatility of nonwovens—polymers, deniers, fiber shapes, etc. - lends to sustainable growth and is only limited by the imaginations of designers, engineers, and those rare, out-of-the-box-thinking entrepreneurs,” Shipley says.
Freudenberg Performance Materials
Freudenberg Performance Materials’ automotive acoustic pads offer weight savings of more than 20% compared to conventional products, as well as remarkable sound absorbing performance, according to the company. Their excellent thermal insulation properties due to high air/fiber ratio are designed for new e-mobility. The pads can be customized based on the customer’s requirements since the material thickness and the selected fibers alter the properties of the nonwoven material. The materials used are “fine-tuned” to ideally cover the specific frequency spectrum desired by car manufacturers. They are easy to process processing for the following applications: insides of doors, trunk lining, headliner, A, B and C pillars, wheel arch liners.Dr. Frank Heislitz, CEO, Freudenberg Performance Materials, says the high sound absorption of the acoustic pads is achieved by the specific ratio of fine and coarse staple fibers in the support layer, as well as the design and material of the flow layer. The interaction between these two layers is also precisely tailored. The support layer developed by Freudenberg Performance Materials is not mechanically sewn in comparison to conventional market products. This lowers weight while the volume remains the same: an important consideration in extending the range of electrically driven vehicles since, for example, heat output in winter can be reduced.
“The material of the flow layer which can also function as an oscillating mass offers further advantages in terms of absorption and weight,” says Dr. Heislitz. “Given the special engineering, the inner nonwoven surface is increased, which improves absorption while keeping the weight low. The flow layer can be used to bond the support layer on one or both sides as needed.”
In the automotive segment, sustainability is driving the change to new mobility. “In this segment, lightweight construction is an important issue in automotive engineering due to governmental regulations concerning CO2 emissions on the one hand,” he explains. “On the other hand, acoustic insulation is important due to less noise in the car interior of e-cars. Freudenberg’s nonwovens can be used very efficiently in lightweight construction and through its superior acoustic properties also the passenger’s comfort in the car interior is improving.”
For applications in buildings, Freudenberg offers SoundTex, a thin acoustic nonwoven that is applied to the back of perforated structures to absorb sound. It is used extensively in a number of applications where acoustics are a prime consideration for either artistic or purely functional reasons. Typical examples include airports, office buildings, municipal halls, theaters, convention centers, subway stations, partitions and furniture in offices all over the world.
With its porous sound absorber, SoundTex converts the sound energy into thermal energy due to viscous friction. “The ultra-thin structure of our acoustic nonwoven makes handling and installation easy,” says Dr. Heislitz. “With a thickness of only 0.27 mm, it provides architects and designers with maximum flexibility by reducing shipping and storage costs at the same time.”
SoundTex can be supplied in roll or sheet form, eliminating the need for manual cutting and fitting. This feature also allows greater use of automated production processes.
“Acoustic nonwovens are air-permeable and do not interfere with certain ventilation processes,” says Dr. Heislitz. “This feature provides architects and designers with greater flexibility in positioning air inlets and vents. Even applications involving heating and cooling systems have proved to be very efficient.”
Hassan Group / Merkas
In its specialized manufacturing process, Merkas has the capability to produce high-volume, tailor-made nonwoven structures using a combination of synthetic and natural fibers, including bio-based raw materials. Within this specialized field, the web formation/nonwoven technical textile production process comprises the alignment of fibers through a carding process and web consolidation followed by air-through thermal bonding technology (ATB).“As is common knowledge, the distinctive attributes of porous materials are highly advantageous for noise control applications,” says Selahattin Onur, R&D manager, Merkas. “Within this context, sound propagation through fibrous materials serves as the inspiration for projects to develop acoustic insulation products created through the utilization of our ATB lines.”
Initial findings revealed that the standard materials produced via Merkas’ ATB lines exhibited noteworthy sound transmission characteristics. Nevertheless, it became evident that their acoustic absorption performance did not reach the expected point. To enhance the acoustic absorption properties, Merkas modernized the process by altering the fiber orientation design integrated to the industrial ATB line. This innovation enabled to the company achieve desired characteristics of sound insulation performance from adapted structure. “Thus, for all practical purposes, the sound insulation range is created using carded air through bonding technology, coupled with a pioneering invention in fiber orientation,” Onur explains.
Since 2021, Merkas has been working on an acoustic project, called Flucpore, with applications in construction, automotive and everyday life. With Flucpore TB products, the company is focused on automotive applications. One of its key innovations involves altering the alignment of fibers to achieve a high loft and light weight. “This innovation aims to provide materials with improved acoustic properties and greater versatility,” says Guldem Yucel, R&D engineer.
Another technical advantage of the Flucpore acoustic insulation series is the unique recovery resilience of their fibers, which resembles foam. “This characteristic provides these fibers with a competitive edge, offering enhanced breathability, reusability, increased loft and a substantial product without excessive bulkiness, offering light weight with excellent sound absorption capacity,” Yucel explains.
Its production range is available from 330 gsm to 1000 gsm to meet specific application areas. This feature holds particular significance for automotive industries, Yucel adds. As part of this project, Merkas is also exploring the application of 2D embossing on an 80 gsm product to enhance its acoustic absorption properties.
Merkas’ plans for the future include expanding its TB range with already existing products named the FP 103, FP 104, FP 105 and FP TB series. Within this scope, its ultimate objective is to reduce product weight while enhancing acoustic performance. Thus, it is collaborating with suppliers and conducting trials to identify areas that require development in accordance with customer needs, both in production and application domains. “We intend to broaden our market presence by conducting experiments with leveraging the flexibility and innovative capabilities of our production lines, and we are experimenting towards creating lighter structures by using thinner raw materials and reducing the fiber diameter to achieve the greatest possible acoustic control,” Yucel says.
According to Onur, the critical domains where noise control is necessary can be categorized into four distinct groups: residential, commercial, automotive and industrial. In residential areas, it is crucial for maintaining a peaceful and comfortable living environment. This includes reducing noise from traffic, neighbors and other sources to ensure that residents can rest, work and engage in daily activities without disruptions.
“Effective acoustic design is necessary to create a productive and pleasant atmosphere. This requires minimizing echo, controlling background noise, and isolating confidential discussions,” says Onur. “Commercial spaces such as markets, hospitals, auditoriums, schools, and dining establishments require effective sound management. The architectural design of buildings and the isolation of sound sources in these locations can contribute to achieving optimal acoustic conditions.”
In industrial settings, sound generated can be intently managed through redesigning of machinery to reduce sound emissions, the physical isolation of machinery within particular chambers to contain sound, and the use of noise barriers to deflect and absorb sound waves, he adds.
Meanwhile, automobiles produce a range of acoustic transmission depending on their velocity and environmental conditions. Acoustic management in automotive aims to minimize the transmission of exterior noises originating from tire, engine and exhaust sources into the vehicle’s interior, as well as the sounds resulting from the interaction of metal and plastic components within the vehicle. “Controlling the noise inside a modern vehicle is critical for manufacturers due to interior noise currently being a competitive quality characteristic of automobiles,” says Onur. “Furthermore, the constraints on automotive noise control are associated with the material’s weight and thickness, which must be optimized to reduce the vehicle’s overall weight.”
Additionally, with the growing demand for electric vehicles, the production and sales of electric cars have surged. The battery of the car is heavier than the other parts. In response to the weight of the battery system, which constitutes the heaviest component in electric vehicles, the design of electric cars necessitates a focus on lightweight materials. This incorporation of lightweight materials helps offset the battery weight and, consequently, reduces the overall weight of electric cars, Onur adds.
To effectively address to this challenge, Merkas has developed a sound absorption range featuring a lightweight fiber network structure. The fibrillar and porous structure of the product helps to trap and dissipate sound energy, reducing reflections and controlling reverberation. Hence, this approach has the potential to result in elevated sound quality and the establishment of a more balanced acoustic environment.
Tenowo
Most of Hof, Germany-based Tenowo’s products end up in the automotive industry, but the company also serves the construction and furniture industries with its acoustic nonwovens. The company’s expertise for acoustic applications is based on three pillars: nonwovens for NVH (Noise, Vibration, and Harshness) auto applications (needlepunched, spunlaced, binder bonded technology); nonwovens designed with special air flow resistance (based on hybrid technology and its own IP for chemical finishing); and thermally bonded high-loft nonwovens with designated thickness and acoustic performance under its brand name Zetaloft+.Tenowo’s nonwovens used for NVH automotive applications can be used for A+B side scrims for hood liners, dash inner- and outer parts, tunnel- and underbody insulation, battery insulation pads, carpet and headliner hybrid parts, as well as beauty cover parts for E- and combustion engines in cars. “Our nonwovens are part of a sandwich construction in combination with different foams, recycled shoddy pads, mineral wool or other core materials,” explains Detlev Käppel, director, Sales Department, Tenowo. “In combination we can provide sound absorption advantages at different frequency levels at a low total weight for the finished part.”
The company’s nonwovens designed with special air flow resistance are enhanced by Tenowo’s own developed finishing/coating step in order to reach a specific air flow resistance. “[This product] helps our customers to reduce weight for its core materials and therefore can save costs by simultaneously reaching required acoustic targets by the OEM level,” he says.
Meanwhile, Tenowo’s Zetaloft+ nonwovens are used as a substitution for other acoustic core materials such as foam. The product can also be used in car seats also where it can substitute spacer fabrics.
Outside of automotive applications, requests for recyclable and sustainable materials in workplace and office areas are always discussed, Käppel says. Nonwovens, mostly thermally bonded high-loft grades like Tenowo´s Zetaloft+, can provide both recyclability and acoustic performance. “Our products are certified according to GRS (global recycled standard) which helps our customers to qualify their finished end product,” he says. “Also, end of life ‘take back’ and a full circular economy concept is the entrance for new developments.”
From Käppel’s point of view, nonwovens are the product of choice when it comes down to 100% recyclable and sustainable raw material concepts, even with fibers being produced by recycled materials, such as PET bottle flakes. “The products can outperform different kinds of core material such as foams by similar performance and cost level. Compared to other products on the market (cross laid), Zetaloft+ nonwovens consist of vertical oriented fibers which provide advantages for ‘recovery force’ and other specification parameters.”
Looking ahead, Tenowo hopes that the entire industry takes the sustainability idea seriously, as sometimes it requires more cost. “The automotive industry especially struggles sometimes to acknowledge this given fact,” he says. “The simple answer is, you can’t have all advantages, being sustainable at lower cost. All industry partners must commit to certain compromises when we want to preserve our environment and future to ensure a better life.”
