How It’s Made: Cotton and Thermal Bonded Nonwovens?

Thermally bonded nonwovens are fabrics made by melting or heating thermoplastic fibers such as polyester, polypropylene etc. When multiple fibers are intersected with the implementation of heat, it melts with each other. Further, when it cools down, a thermal bond forms between them. This brings strength to the fabric.

The thermal bonding nonwoven fabrics are light in weight or thick, or they can also be thick and heavy. These fabrics have numerous applications in the textile industry. The lightweight nonwoven is used in sheets or coverstocks, while the thicker fabric is used for insulating and cushioning. Cotton is used in the thermal bonded nonwoven to make the fabric soft for other purposes.

Methods Of Manufacturing Thermal Bonded Nonwovens

There are principle methods of preparing thermal bonding nonwoven. These stepwise methods are organized, resulting in a complete fabric that is ready for utilization in various applications. The thermal bonding process of nonwovens begins with thermoplastic fibers. It is also blended with non-thermoplastic fibers such as cotton. Further, it forms into a fiber batt with the help of air-laying machines. The webs undergo thermal processes through various methods.

Method -1 Calendering

The initial step of preparing the thermal bonding nonwoven fabrics is calendaring. The fiber webs are passed between the heat rolls in this process under significant pressure. Due to the pressure, the webs squeeze together. The pressure applied flattens the fiber web and makes it flat and thin.

The solid rolls result in melting the thermoplastic fiber producing a solid and stiff fabric. Point bonding is another process in this method. The bonding forms at the fiber’s intersection between the raised parts of the rolls. This results in flexible, flat and soft fabrics.

Method -2 Ultrasonic

The second method is Ultrasonic, where a device is used to produce heat. It uses ultrasonic energy, which replaces the top drum and produces fabrics like a calendering process. High-frequency vibrations accomplish ultrasonic bonding to the webs. Thermal energy is generated in a web that rises its temperature. It is further sufficient to weld fibers at the bonding site.

Method -3 Through Air Bonding

The through-air bonding is a thermal bonding process that involves heated air application at the non-woven fabric surface. Webs that are produced run through an oven and heat on one side. And on the other side, the negative pressure pulls the hot air. It lets the web melt and bond fibers. It allows the heat to pass through the entire web. The fabric produced is lofty and thick. But when the web is sandwiched while heating in between the belts, it results in thin fabrics.

These above methods are considered major for thermal bonding in nonwoven fabrics.

How Is Cotton Used In Thermal Bonded Nonwoven Fabrics?

Cotton is used to produce thermal bonding nonwoven fabrics. Cotton fibers are blended with thermoplastic fiber such as polypropylene, polyester, polyethylene, etc. Cotton-surfaced nonwovens are developed with cotton on one side or both sides; at times, the cotton content is also 41 to 75% of the entire fabric weight. The thermally-bonded three-layered laminates are soft and strong enough. It is also similar to cotton knits or hydroentangled fabrics.

Moreover, the cotton fibers are also blended up to 80% to produce a fine fabric. But the strength of the fabric is due to the presence of the melting process of thermoplastic fibers melting at the fiber intersections. Therefore, the more cotton is added, the fabric becomes less strong. But these cotton thermal bonded nonwoven fabrics are best suitable for manufacturing soft covers, cushioning etc.

These nonwoven fabrics have the best physical properties, such as excellent wetting, water adsorption wicking rates, and water retention properties. These also have extensibility and flexibility. The post-treatment process results in instantaneous elastic recoveries in fabrics from 83 to 93%, with an extension of 50%. These produced fabrics also have minimal linting characteristics.

The cotton used thermal bonded nonwoven fabrics are used in manufacturing various textile materials such as head covers and shoe covers, medical isolation gowns, bed sheets, pillowcases and other sheets. It is also utilized in consumer applications products such as towels, wipers, disposable underwear, and personal hygiene products. The textile industries highly supply thermal bonded non-woven products due to their massive demand in medical and industrial sectors.