Introduction
Nonwoven fabric production is relatively new. Over the last few decades, it has created a very healthy impression. In the USA and Europe, nonwoven companies continuously increase their production capacities and installed new plants and modern equipment. According to the statistics of 1978 compared with 1947. The uses of nonwovens are both disposable and durable. Disposable products are for sanitary and medical uses, i.e., hygiene products and surgical dressings. Durable uses are apparel and furniture padding, thermal insulation material, reinforcing materials, linings, decorative textiles, household textiles, and industrial and technical materials such as geotextiles. The most important reason for the increased use of nonwovens is their economical manufacturing process. Viscose, polyester, polypropylene, cotton, wood pulp, and waste fibers are the most used fibers for nonwoven production.
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Production Process
Nonwoven can be produced from:
- Staple fiber webs
- Spun-laid continuous filament
For the production of nonwovens from staple fibers, a carding process is required for fiber separation and web formation. The webs produced by this system are known as dry-laid webs. Dry-laid webs are subdivided according to fiber orientation into three types.
- Parallel laid
- Cross laid
- Random laid
The carded or opened fiber can be processed to random or isotropic webs by means of sucking on to screen cage or condenser (air-laid)
Another system of web preparation is wet-laid. In the preparation of this, a fiber slurry is collected on a wire mesh, condensed to form a web, and finally dried.
An essential feature of web production is to produce a uniform web. The quality of the nonwoven is dependent on the properties of the fiber, the fiber orientation on the web, the mass of fiber per unit area, and the technique of fiber bonding.
Several web bonding methods are used for the production of nonwoven fabric.
1. Adhesive Bonding
- by saturation padding
- by printing
- by foam
- by spraying
2. Thermal Bonding
- by applying heat on
- thermostatic fibers
- bicomponent fibers
- thermoplastic power
3. Mechanical Bonding
- by needle punching
- water jet entanglement
4. Stitch Bonding
Powder Bonding Technique
The basic concept of the powder bonding technique for the production of nonwoven was developed by Eastman Chemicals, USA. Under an agreement with Bonar Fabrics of S. Carolina (USA), Eastman Chemicals developed its commercial viability. The powder bonding process has increased in use since 1987, with new high-performance lines installed in the USA and UK. The advantages of this process are softness, strength, and diversity over a wide range of weights. Bonar Carelle of the UK produces ultrasoft fabrics. The ultrasoft fabrics are manufactured in a dense or condensed form. By the application of heat, they achieve an increase in thickness (loft) of up to 10 times their thickness in the condensed form. (figure 1 and 2)
Mechanism of Production
Ultrasoft fabrics are produced from dry-laid carded fibers with the application of a fine, low-melt adhesive powder binder to the web. Multilayer fabrics can also be produced by this process.
To create a three-dimensional image, the dense Ultrasoft is printed with a picture or pattern. Then, when the material is heated and lofted, the printed fibers distribute themselves through the depth of the lofted structure. Because the very little lateral movement of the fibers occurs, the image remains sharp in the X and Y dimensions, while the increase in thickness creates the 3D effect.
By introducing “loft” or “bulk” in the fabric at a later stage in the manufacturing process of garments and other products, the performance and cost factors are improved. There is a reduction in transport, storage and waste costs and there is easier handling of material.
Flow Chart of Dry Powder Bonding Process for Nonwoven
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| Flowchart of Powder Bonding Production ©Textile Pad |
Typical Powder Bonding Line for Making Nonwoven Using Pet Powder
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| Powder Bonding Line ©Textile Pad |