Patterned Calender Roll for Smooth Tissue With Bulk Retention
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Solution Overview
Problem
Conventional calendering processes result in significant loss of Sheet Bulk and stiffness when producing spirally wound tissue products, leading to a decrease in Roll Bulk and undesirable firmness, which affects the overall quality and consumer preference of tissue rolls.
Innovation Solution
The use of a patterned calender roll with male elements covering 60 to 95% of the surface area, providing a nip with variable loading to reduce Z-direction variability and maintain Sheet Bulk while achieving surface smoothness, involves a cylindrical roll with landing areas and male elements having a specific elevation difference, and a resilient roll to create a calender nip without excessive compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional calendering is used to smooth the tissue surface, then surface smoothness is improved, but sheet bulk is significantly reduced
Solution Approach 1:
The calender roll surface is divided into different zones with distinct functions: smooth landing areas for bulk retention and patterned male elements for localized smoothing. This local differentiation allows the tissue web to be smoothed only where needed while preserving bulk in other areas.
Solution Approach 2:
The calender roll surface is segmented into discrete male elements (protrusions) separated by landing areas (depressions). This segmentation creates a patterned surface that applies compression locally rather than uniformly, enabling selective smoothing while maintaining overall sheet bulk.
2Manufacturing precision
If conventional calendering is used to achieve surface smoothness, then the tissue product becomes smoother, but the roll bulk is reduced
Solution Approach 1:
The patterned calender roll applies smoothing action only at specific locations (male elements) while leaving other areas (landing areas) to preserve bulk. This localized approach produces tissue with adequate surface smoothness that maintains higher roll bulk when wound.
3Manufacturing precision
If conventional calendering is used to smooth the tissue, then surface smoothness is improved, but the tissue becomes stiffer
Solution Approach 1:
The calender surface is segmented into male elements and landing areas, creating a patterned compression effect. This segmented approach smooths the tissue surface while the intermittent nature of compression (rather than continuous) prevents excessive stiffening, maintaining tissue flexibility.
4Manufacturing precision
If conventional calendering is used to improve surface smoothness, then the tissue surface is smoother, but the roll firmness becomes undesirable
Solution Approach 1:
The patterned calender roll provides localized smoothing through male elements while landing areas allow bulk retention. This creates tissue with balanced properties: smooth enough surface for consumer acceptance combined with adequate roll firmness for handling and dispensing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in tissue products with improved Sheet Bulk, Surface Smoothness, and Roll Structure, maintaining caliper and bulk retention when wound into rolls, offering a balance of softness and firmness, thus enhancing the quality and aesthetics of spirally wound tissue products.
Implementation Method 1
The male elements, which may generally be any shape, have a surface area greater than about 300 mm2, such as from about 300 to about 8,000 mm2 and more preferably from about 1,750 to about 3,000 mm2 and cover from about 60 to about 98 percent of the surface of the roll and more preferably from about 70 to 95 percent of the surface of the roll
Data Source
AI summary
The novel tissue products of the present invention are generally produced by calendering a tissue basesheet using at least one patterned roll. In one embodiment the patterned roll replaces the flat steel roll commonly used in calendering. The elements on the patterned roll provide a means of providing a nip having variable loading that yields a web having a smooth surface without subjecting the web to excessive compression forces and preventing excessive caliper loss. Thus, webs converted according to the present invention have comparable or better surface smoothness compared to webs converted using conventional calendering means and also retain a greater percentage of their caliper and bulk.