Hot air non-woven fabric belongs to a type of hot air bonded (hot-rolled, hot air) non-woven fabric. Hot air non-woven fabric is produced by using hot air from a drying equipment to penetrate the fiber web after the fibers are combed, allowing it to be heated and bonded together. Let’s take a look at what hot air non-woven fabric is.
Principle of hot air bonding
Hot air bonding refers to the production method of using hot air to penetrate the fiber mesh on drying equipment and melt it by heating, resulting in bonding. The heating method used is different, and the performance and style of the products produced are also different. Generally, products made by hot air bonding have characteristics such as fluffiness, softness, good elasticity, and strong warmth retention, but their strength is low and they are prone to deformation.
In the production of hot air bonding, a certain proportion of low melting point bonding fibers or two-component fibers are often mixed into the fiber web, or a powder spreading device is used to apply a certain amount of bonding powder to the fiber web before it enters the drying room. The melting point of powder is lower than that of fibers, and it quickly melts when heated, causing adhesion between fibers. The heating temperature for hot air bonding is generally lower than the melting point of the main fiber. Therefore, in the selection of fibers, the matching of thermal properties between the main fiber and the bonding fiber should be considered, and the difference between the melting point of the bonding fiber and the melting point of the main fiber should be maximized to minimize the thermal shrinkage rate of the main fiber and maintain its original properties.
Main raw materials
ES fiber is the most ideal thermal bonding fiber, mainly used for non-woven fabric thermal bonding processing. When the combed fiber network is subjected to hot rolling or hot air penetration for thermal bonding, low melting point components form melt adhesion at the intersections of the fibers, while after cooling, non intersection fibers remain in their original state. This is a form of “point bonding” rather than “zone bonding”, thus the product has characteristics such as fluffiness, softness, high strength, oil absorption, and blood sucking. In recent years, the rapid development of thermal bonding applications relies entirely on these new synthetic fiber materials.
After mixing ES fibers with PP fibers, heat bonding or needle punching treatment is carried out to crosslink and bond ES fibers, which has the advantage of not requiring adhesives and substrate fabrics.
Production process
Overview of Three Production Processes
One step method: Open the package, mix and loosen → Vibration quantitative cotton feeding → Double Xilin Double Dove → Wide width high-speed combing into a net → Hot air oven → Automatic coiling → Slitting
Two step method: opening and mixing cotton → cotton feeding machine → pre combing machine → web laying machine → main combing machine → hot air oven → coiling machine → slitting machine
Craftsmanship and Products
Hot bonded nonwoven fabrics can be achieved through different heating methods. The bonding method and process, fiber type and combing process, and web structure will ultimately affect the performance and appearance of non-woven fabrics.
For fiber webs containing low melting point fibers or two-component fibers, hot rolling bonding or hot air bonding can be used. For ordinary thermoplastic fibers and fiber webs mixed with non thermoplastic fibers, hot rolling bonding can be used. Under the same web forming process, the thermal bonding process has a significant impact on the performance of non-woven fabrics and determines the purpose of the product.
The main factors affecting the performance of hot air bonded nonwoven fabrics are:
In the process of hot air bonding, the carrier of heat is hot air. As the hot air penetrates the fiber mesh, it transfers heat to the fibers, causing them to melt and produce bonding. Therefore, the temperature, pressure, fiber heating time, and cooling rate of the hot air will directly affect the performance and quality of the product.
As the temperature of the hot air increases, the longitudinal and transverse strength of the product also increases, but the softness of the product decreases and the hand feel becomes harder. Table 1 shows the changes in strength and flexibility with temperature during the production of 16g/m products.
Hot air pressure is an important parameter that affects hot air bonding products. Generally, as the quantity and thickness of the fiber web increase, the pressure should be correspondingly increased to allow the hot air to pass through the fiber web smoothly. However, before the fiber web is bonded, excessive pressure can damage its original structure and cause unevenness. The heating time of the fiber web depends on the production speed. To ensure sufficient melting of fibers, there must be sufficient heating time. In production, when changing the production speed, it is necessary to increase the hot air temperature and pressure accordingly to ensure the stability of the product.
Product application
Hot air bonding products have the characteristics of high fluffiness, good elasticity, soft hand feel, strong warmth retention, good breathability and permeability, but their strength is low and they are prone to deformation. With the development of the market, hot air bonding products are widely used in the manufacturing of disposable products with their unique style, such as baby diapers, adult incontinence pads, fabrics for women’s hygiene products, napkins, bath towels, disposable tablecloths, etc; Thick products are used to make anti cold clothing, bedding, baby sleeping bags, mattresses, sofa cushions, etc. High density hot melt adhesive products can be used to make filter materials, sound insulation materials, shock absorption materials, etc.
Dongguan Liansheng Nonwoven Fabric Co., Ltd., a manufacturer of non-woven fabrics and non-woven fabrics, is worthy of your trust!
Post time: Aug-11-2024