Nonwoven Textiles: Types of Nonwoven Manufacturing Process

Nonwoven textiles are all around you, in products you use every day. As you go about your daily routine, nonwoven materials provide functionality and comfort in the form of wipes, filters, insulation, and medical products. Although nonwoven fabrics have been in use since the early 1900s, recent technological advancements have enabled an explosion in the diversity and applications of these versatile, engineered fabrics.

In this article, you will learn about the major types of nonwoven textiles. An overview of the manufacturing processes for creating nonwoven materials through mechanical, thermal, and chemical bonding will provide insight into how these fabrics achieve the desired balance of properties for their intended end uses. From disposable wipes to advanced composite materials used in aerospace, nonwovens have permeated nearly every industry. Read on to discover more about these remarkable, yet often unrecognized, fabrics that continue to improve lives through enhanced performance, lower cost, and reduced environmental impact.

Types of nonwoven textiles

the major types of nonwoven textiles, including spunbond, meltblown, needlepunched, and spunlaced fabrics.

Spunbond Nonwovens:

Spunbond nonwoven textiles are Durable and Versatile

As one of the most common and versatile nonwoven fabrics, spunbond nonwovens are durable, lightweight, and made from spun polypropylene or polyester fibers. They are highly useful for applications where strength, stability, and permeability are required.

Spunbond nonwovens are made through a spunmelt process, where molten polymer is extruded through spinnerets to form continuous filaments that are rapidly cooled and drawn. The filaments are then deposited onto a moving conveyor belt in a random swirl pattern and thermally bonded to form a strong, nonwoven web. This continuous process allows spunbond fabrics to be produced very efficiently in high volumes.

Some key characteristics of spunbond nonwovens include:

• Durability and strength: The thermal bonding process creates a durable fabric that maintains its strength even after processing or in end-use applications.
• Breathability and versatility: Spunbond fabrics provide an excellent balance of breathability and barrier protection. They can be tailored to specific needs by adjusting polymer type, filament diameter, web density, and bonding pattern.
• Cost-effectiveness: The spunmelt process is highly automated, requiring little manual intervention. This results in very cost-competitive fabrics.
• Recyclability: Spunbond polypropylene fabrics can be recycled and used again to make new spunbond fabrics. Some spunbond fabrics contain up to 100% recycled content.
• Wide range of applications: Spunbond nonwovens are utilized in products like diapers, medical gowns and drapes, filters, roofing materials, and geotextiles. They are valued for their strength, processability, and affordability.
• Spunbond nonwovens are prized for their exceptional functionality, durability, and cost-efficiency. Their unique properties have made them integral components of many important products used every day. Overall, spunbond fabrics will likely remain a vital part of the nonwovens industry for years to come.

Meltblown Nonwovens:

Meltblown nonwovens are composed of extremely fine fibers that are ideal for filtration applications. To produce meltblown fabrics, polymers are melted and blown into fibers as they pass through small orifices in a die. Hot air blows and attenuates the fibers into a random orientation, creating a thin, porous sheet.

Filtration properties:

Meltblown nonwovens are known for their effective filtration properties, as their fine fibers and interlocking web structure create a tortuous path that efficiently traps particles and contaminants. The fibers in meltblown fabrics are typically 1 to 10 microns in diameter, much smaller than standard spunbond fibers. This results in higher surface area and more interfiber spaces, which are ideal for capturing particles.

The meltblowing process utilizes a die with many small holes through which molten polymer is extruded and blown by hot air. As the fibers exit the die, the hot air stream blows and stretches them, creating thin fibers that intertwine and bond together as they land on a moving belt to form a web. Meltblown webs are usually soft, lightweight, and high loft. They can also be an inexpensive alternative to spunbond fabrics for some applications.

Common uses of meltblow nonwovens

Meltblown nonwovens are commonly used for disposable respirators, surgical masks, air filters, and other products where high performance filtration is required. They are also widely used as insulation in jackets, as medical fabrics, and in industrial wipes and fabrics. The meltblowing process can produce nonwoven sheets at high speeds and volumes, keeping costs low while achieving the necessary performance for filtration and other applications. With their fine, efficient fiber structure, meltblown nonwovens will likely continue to play an important role in filtration and as alternatives to traditional textiles.

Spunlace Nonwovens:

Spunlace Nonwovens are most Absorbent and Hydroentangled.

Manufacturing Process

The spunlace nonwoven fabric manufacturing process is also known as hydroentanglement. It is a mechanical bonding process that uses high-pressure water jets to entangle fibers and create a strong bond without the use of chemical binders. This results in a soft, absorbent, and flexible nonwoven material.

The spunlace process begins with fiber opening and blending. Staple fibers, such as rayon, polyester, cotton or wood pulp are opened, cleaned and mixed to the desired blend. The fibers are then formed into a web using carding machines. Next, the web goes through a series of high-pressure water jet treatment using entangling chambers.

In the entangling chambers, multiple rows of water jets shoot columns of pressurized water at the web. The water jets physically entangle the fibers, tangling them together to form a fabric. As the web passes through subsequent chambers, the level of entanglement increases producing a stronger and more uniform fabric.

The entangled web then moves onto a vacuum slot to remove excess water. It is then dried using heated rollers and wound into rolls. Some spunlace fabrics receive additional finishing treatments such as embossing or dyeing before being sent to converters for various end-uses.

Properties

Spunlace nonwovens are highly absorbent, soft and drapable. They are also very versatile and can be engineered to suit different needs. Key properties include:

• High wet strength and absorbency: The hydroentangled fibers form a porous structure that can quickly absorb and retain liquids.
• Soft and flexible: Spunlace fabrics have a texture similar to woven textiles and are very pliable.
• Durable: The mechanical bonding of spunlace nonwovens produces strong yet lightweight fabrics.
• Versatile: Spunlace fabrics come in a range of basis weights suited for various applications like wipes, medical fabrics, and hygiene products.
• Eco-friendly: Spunlace nonwovens are made from natural fibers and don’t require chemical binders. They are biodegradable and compostable.

Spunlacing is a popular nonwoven manufacturing process that creates soft, absorbent and high-performance fabrics for hygiene, medical, and industrial uses. The hydroentanglement bonding technique results in durable and eco-friendly nonwoven materials with properties that rival traditional textiles.

Needle punch Nonwovens:

Needlepunch Nonwovens are Felted and Fluffy

Needlepunch nonwovens are produced by mechanically entangling fibers using barbed needles. This interlocks the fibers to form a felt-like material without the use of binders or adhesives. Needlepunch fabrics can be made of natural fibers like wool, synthetic fibers such as polyester or polypropylene, or blends of multiple fibers.

The basic steps in the needlepunch process are:

1. Fiber opening and blending. Fibers from bales are opened, blended and fed into the carding machine.
2. Carding. Carding untangles the fibers and aligns them in one direction to form a web.
3. Crosslapping. Webs from multiple cards are layered at right angles to strengthen the material.
4. Needling. Barbed needles repeatedly penetrate the web, pushing fibers into and around each other to form an interlocked network.
5. Finishing. The needlepunched fabric goes through processes like dyeing, printing, coating or laminating depending on the end use.
6. Felted needlepunch fabrics have a dense, felt-like structure. They are generally made of wool or other animal fibers that can felt together. Felted fabrics are thick, fuzzy and provide good insulation.
7. Fluffy needlepunch fabrics have a more open, voluminous structure created by needling lightweight, crimped fibers. They have a high bulk-to-weight ratio and are used for applications like furniture padding, filtration and insulation.

The main properties of needlepunched nonwovens include:

Absorbency: Can absorb and retain moisture depending on fiber type. Wool felts are very absorbent.

Bulkiness: Fluffy needlepunch fabrics provide high bulk relative to weight.

Durability: Interlocked fiber structure provides good strength and abrasion resistance.

Insulation: Air pockets in the felt provide thermal insulation. Dense wool felts insulate well.

Permeability: Degree of permeability depends on fiber type, needling density and thickness. Can be engineered for specific filtration requirements.

Needlepunch nonwovens have a wide range of applications like automotive insulation, carpet backings, geotextiles, industrial wipes and medical/hygiene products. Proper selection of fibers and optimizing the needling process produces needlepunched fabrics with desired properties for the end use.

Thermal Bond Nonwovens:

Fusing Fibers With Heat

Thermal Bonding Process

Thermal bonding is a manufacturing process where heat and pressure are applied to fuse fibers together into a fabric. Thermal bonding is used to produce nonwoven fabrics with good strength, durability and absorbency. The basic steps in the thermal bonding process are:

1. Fiber opening and blending: Fibers from bales are opened, blended and fed into the carding machine. This process opens up fibers and aligns them in one direction.
2. Web formation: The carded fiber web is cross-lapped to form a isotropic web. The web can also be strengthened by increasing the basis weight. The web goes through a drafting process to improve uniformity.
3. Bonding: The web then passes through the bonding unit where heated calender rollers apply heat and pressure to fuse fibers at multiple points. The bonding temperature depends on the fiber type, lower for heat-sensitive fibers like polypropylene and higher for polyester. The bonding pattern can be changed to produce fabrics with different properties.
4. Winding: The bonded fabric is wound into rolls and ready for slitting, packaging and shipping.

Types of Thermal Bonded Nonwovens

• Spunbond nonwovens: Made from spunbond technology, using spunlaid webs bonded by hot calender rollers. Produces high strength fabrics with good uniformity. Uses: disposable products, geotextiles, furniture pads.
• Meltblown nonwovens: Made from meltblown technology where molten polymer fibers are blown onto a moving belt and bonded. Produces lightweight fabrics with good barrier properties. Uses: filtration, sorbents, insulation.
• Thermal laminates: Two or more webs are bonded together under heat and pressure to form a laminate. Provides enhanced strength, absorbency or other properties compared to individual webs. Uses: medical disposables, industrial wipes.
• Airlaid nonwovens: Made from latex, cellulose or synthetic fibers that are air laid into a web and thermally bonded. Highly absorbent, high bulk fabrics. Uses: Absorbent cores in diapers, feminine hygiene products.

Thermal bonding is a versatile, efficient and economical process for manufacturing a wide range of nonwoven fabrics to suit different end-use applications. Proper selection of fibers, bonding patterns and operating conditions can produce nonwovens with the desired properties.

Composite Nonwoven Fabrics:

Combining the Benefits

Combining Fibers

Composite nonwoven fabrics utilize a combination of fibers to achieve specific properties for end-use applications. By blending fibers, manufacturers can create nonwovens with customized characteristics that single component fibers alone cannot provide.

Polymer and Natural Fiber Blends

Blending synthetic polymer fibers with natural fibers like cotton or wool creates nonwovens that are both durable and breathable. Polypropylene or polyethylene fibers provide strength and abrasion resistance while natural fibers increase air permeability and absorbency. These types of composite nonwovens are often used for hygiene products, wipes, and medical applications.

Microfiber and Spunlace

Microfiber nonwovens, made up of extremely fine synthetic filaments, can be combined with a spunlace process to produce a fabric with exceptional softness, drapability, and fluid barrier properties. Spunlacing, also known as hydroentanglement, uses high-pressure water jets to entangle the fibers into a fabric. Adding microfiber filaments to wood pulp or rayon produces a nonwoven that is soft as silk yet still economical. These composite fabrics are ideal for clothing, furnishings, and industrial wipes.

Meltblown and Spunbond

The meltblown process produces nonwovens with very fine fibers and pores, resulting in high barrier and filtration properties. Combining meltblown fibers with the larger fibers of spunbond nonwovens creates a composite fabric with a good balance of barrier, strength, and cost-effectiveness. These “SMS” fabrics, containing spunbond-meltblown-spunbond layers, are widely used for hygiene products, medical gowns and drapes, and protective apparel.

In summary, composite nonwovens fuse the benefits of different fiber types and nonwoven manufacturing processes into multifunctional fabrics tailored for specific end-uses. By strategically combining fibers and production methods, nonwoven manufacturers can create materials with customized properties unattainable using a single method or component. The possibilities for developing innovative composite nonwoven fabrics are extensive.

The Nonwoven Manufacturing Process:

From Fibers to Fabric

The manufacturing of nonwoven textiles involves a multi-step process to convert fibers into fabric. This process includes several stages to produce a final nonwoven product with specific properties for the intended end use.

Fiber Selection and Opening

The first step is selecting fibers based on the desired characteristics of the final nonwoven product. The fibers are then opened and blended, a process that separates compressed fibers and mixes different fiber types. Common fiber types for nonwovens include polypropylene, polyester, rayon, and wood pulp.

Web Formation

The opened fibers are formed into a web, a thin sheet of interlocked fibers. The main web formation methods are dry laid, wet laid, and polymer laid.

• Dry laid webs are formed by carding the fibers and using air to deposit the fibers onto a moving belt. This method is used to produce nonwovens like felts.
• Wet laid webs are formed using water to disperse and deposit the fibers onto a moving screen, then dried. This produces nonwovens such as paper and other cellulosic fabrics. – Polymer laid webs are formed by extruding polymer fibers directly onto a moving belt. This method is used to make nonwovens such as spunbond and meltblown fabrics.

Bonding

The web is bonded using mechanical, thermal, or chemical techniques to provide strength and structure.

• Mechanical bonding uses needles to physically interlock fibers. This produces needlepunched nonwovens used as filters, geotextiles, and furnishing fabrics.
• Thermal bonding applies heat to melt fibers and fuse them together, as in spunlace and spunbond nonwovens.
• Chemical bonding uses adhesives and binders to join fibers. This method produces nonwovens such as wet wipes, medical fabrics, and paper products.

Finishing

Optional finishing treatments may be applied to improve properties like absorbency, flame resistance, stain resistance, or softness. Finishes are selected based on the end use requirements of the nonwoven product.

Winding and Packaging

The finished nonwoven fabric is wound onto rolls and packaged for distribution and sale. Nonwoven roll goods are converted into end products by manufacturers for use by both consumers and industrial customers.

In summary, the key steps to produce nonwoven textiles are fiber selection and opening, web formation using dry laid, wet laid or polymer laid methods, bonding via mechanical, thermal or chemical techniques, optional finishing, and winding and packaging the final nonwoven fabric.

Conclusion

In conclusion, nonwoven textiles offer a versatile and sustainable alternative to traditional woven fabrics. The variety of nonwoven manufacturing processes allow for customization to suit different applications and performance requirements. Nonwoven textiles continue to expand into new areas due to their versatility, cost-effectiveness, and environmentally-friendly nature. As a consumer, understanding the types of nonwovens and how they are made can help you make more informed choices. The next time you use a wipe, medical fabric or other nonwoven product, you can appreciate the technology and innovation that went into creating that engineered fabric.