In search of lofty spunbond webs for applications including hygiene and health care: Pegas invention uses thermal calender entrained air




CLOVERDALE, CA, April 17, 2014-

Many market applications utilizing nonwoven fabrics benefit from webs which are soft and thick or lofty while also having good mechanical properties such as strength. Many treatment methods have been developed to enhance the loft of nonwoven webs such as through-air bonding, hydroentangling, three-dimensional fiber crimping and creping. Web softness can also be obtained by a variety of technical approaches but is uniquely made challenging due to the difficulty in measuring the property and the complexity associated with product consumer perceptions. It is believed that consumer perceived softness combines tactile signals, auditory signals and visual signals. Tactile softness may be impacted by various materials properties such as loft, fiber thickness and density, microscopic pliability, fiber flexibility within the matrix, surface friction, bonding technique and other factors. Web loft also plays a role in the visual impression of softness along with other features and properties such as color, opacity, light reflectivity, refractivity or absorption.

In this patent application by Pegas Nonwovens, low-weight, high-loft, soft and strong spunbonded nonwovens are produced utilizing the process and method of the invention. Central to the invention is a specific, thermal bonding pattern which capitalizes on the available entrained air surrounding the calendar to add web caliper during bonding. In a key embodiment, the bonding pattern protrusions resemble airfoils or aircraft wings. The protrusion shapes, positioning and configurations channel the airflows during calendering in a manner to reposition the spunbond fibers, fluff the web and add loft. The technology can be utilized at a line speed over 800 m/min. to produce spunbond webs at a basis weights as low as 10-20 gsm. The process uses a low amount of energy, requires no added equipment and does not sacrifice the mechanical properties for loft in low weight webs.


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