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New Manufacturing Techniques Can Add a Variety of Apertures to Nonwoven Material
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| (fig. 1) Rollers, nubs, and anvil cause tears in web |
Nonwoven materials have been around for many years and used in a wide variety of consumer goods, particularly disposable diapers and other personal hygiene products. However, the manufacturing methods used to create porous nonwoven webs usually involved punching or puncturing, which created lint and debris, making it a slow and relatively costly process. However, Procter & Gamble has developed a new technology to create apertures within nonwoven webs through a high-speed process that combines stressing and controlled tearing.
Nonwoven webs are typically manufactured from synthetic fibers, usually a polyolefin such as polyester, polyethylene, or polypropylene. The fibers are interlaid together in no particular pattern using such methods as meltblowing and spunbonding. The result is a strong, inexpensive sheet or fabric suitable for any number of uses, including disposable diapers, bed clothing, furniture covers, and more.
To make a nonwoven web porous, apertures need to be added. However, the techniques commonly used to create the openings are either costly or create a texture that is rough against the skin, making it less than ideal for wearable goods. Thatīs why Procter & Gamble has developed a new technology that enables a manufacturer to control the size, shape, and placement of the apertures without creating lint, debris, or any unpleasant texture.
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| (fig. 2) Striking causes surface weakness with enough heat to stabilize fibers |
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| (fig. 3) Stretched membrane creates tears |
The method is a relatively simple one: the web membrane is passed between two rollers, one containing raised features, or nubs, to create the aperture pattern, the other a smooth surface, or anvil, for the nubs to strike against (Fig. 1). The process of the striking causes a surface weakness in the web while the friction creates enough heat to melt-stabilize the nonwoven fibers (Fig. 2). The web is then passed through another set of rollers, or ringroll, which stretch the membrane either across the direction of travel or along it, creating tears in the weakened patterns created by the first set of rollers (Fig. 3). These tears are controlled by the melt-stabilized fibers, making it easier to control porosity and create complex filters. By conditioning and modifying the nonwoven web, common nonwovens, along with nonwoven/film composites, can be used to create any number of finished products, enabling the lowest cost material to be used. The entire process is high speed and low energy, helping to further lower production costs while maintaining quality and consistency.
The soft, breathable, porous materials that can be manufactured with this process are ideal for a wide range of applications, including personal hygiene products, clothing, filtering systems, furniture coverings, medical products, and architectural fabrics, to name a few.
