Across the globe there is great demand for disposable paper products such as sanitary tissue and facial tissue. In the North American market, the demand is increasing for higher quality products offered at a reasonable price point. The quality attributes most important for consumers of disposable sanitary tissue is softness and strength. Another attribute desired by consumers is low lint, which refers to the amount of fibers that are liberated from the product during use.
Fabric crepe is the process of using speed differential between a forming and structured fabric to facilitate filling the valleys of the structured fabric with fiber, and folding the web in the Z-direction to create thickness and influence surface topography. Conventional creping is the use of a doctor blade to remove a web that is adhered to a steam heated cylinder (yankee dryer), coated with an adhesive chemistry, in conjunction with speed differential between the yankee dryer and reel drum to fold the web in the Z-direction to create thickness, drape, and to influence the surface topography of the web. The process of calendering, pressing the web between cylinders, will also affect surface topography. The surface topography can also be influenced by the coarseness and stiffness of the fibers used in the web, degree of fiber refining, as well as embossing in the converting process. Added chemical softeners and lotions can also affect the perception of smoothness by creating a lubricious surface coating that reduces friction between the web and the skin of the consumer.
Lint, or the amount of fibers liberated from the web during use can be affected by many things such as the overall strength of the web, the incorporation of natural or synthetic binders (especially in outer surface of the web which is exposed to direct contact with the consumer), the smoothness of the outer surface of the web, the size of the fibers or stratification of the fibers throughout the web, and the geometry of the creping doctor used to crepe the sheet from the yankee dryer.
USPTO Backgrounds
USPTO Backgrounds