CNT Impression Roller Surface for Uniform ESA Rotogravure Conductivity
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Solution Overview
Problem
Existing impression rollers for electrostatically assisted (ESA) rotogravure printing face issues with inhomogeneous electric resistance profiles, leading to inconsistent ink transfer and poor impression quality, and are complex to fabricate, with known solutions either being incompatible with ESA rotogravure or failing to maintain constant resistance under varying tensions.
Innovation Solution
An impression roller with a stiff cylindrical core coated with a nanocomposite surface comprising a basic polymer matrix, amorphous carbon, and multi-walled carbon nanotubes, which allows for precise control of electric conductivity and mechanical properties, ensuring a homogeneous and predictable resistance profile even under different tensions and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a layer of semiconductor material with conducting elements is used to control electric resistance, then the electric resistance value can be adjusted, but the fabrication process becomes complex and the resistance profile becomes inhomogeneous
Solution Approach 1:
The patent applies composite materials by combining a polymer matrix with carbon nanotubes to create a nanocomposite impression roller surface. This composite structure provides both the desired electrical conductivity and mechanical properties while maintaining fabrication simplicity. The carbon nanotubes dispersed in the polymer matrix create a homogeneous conductive network throughout the roller surface, eliminating the need for separate semiconductor layers and conducting elements.
Solution Approach 2:
The patent changes the material parameters by using carbon nanotubes with specific aspect ratios, lengths, and concentrations within the polymer matrix. By controlling these parameters during fabrication, the patent achieves predictable and homogeneous electric resistance profiles. The carbon nanotube concentration and distribution can be precisely controlled during mixing and curing, allowing for consistent electrical properties across the roller surface.
2Reliability
If the electric resistance value is set under an initial tension value, then the resistance can be controlled, but the resistance value deviates when operational tension differs from the initial tension
Solution Approach 1:
The patent addresses tension sensitivity by carefully selecting polymer matrix materials with appropriate elastic moduli and carbon nanotube aspect ratios. These parameter selections ensure that the nanocomposite structure maintains its electrical properties across a range of operational tensions. The carbon nanotube network's three-dimensional connectivity provides mechanical robustness that prevents significant resistance changes during roller operation.
Solution Approach 2:
The composite structure of carbon nanotubes embedded in the polymer matrix creates a mechanically robust electrical network. The carbon nanotubes form a percolating conductive pathway that is less sensitive to mechanical deformation compared to surface-mounted conducting elements. This composite architecture maintains electrical connectivity even when the roller experiences tension variations during operation.
3Manufacturing precision
If carbon nanotubes are used to improve surface roughness for ink holding, then the microscopic surface properties are enhanced, but the electric conductivity and resistance control are compromised
Solution Approach 1:
The patent successfully combines surface roughness enhancement with electrical conductivity control through the nanocomposite structure. The carbon nanotubes create a microscopically rough surface that improves ink adhesion and holding, while simultaneously forming a conductive network within the polymer matrix. The dual functionality is achieved because the carbon nanotubes serve both as surface texture elements and as electrical conductors throughout the impression roller surface.
Solution Approach 2:
The patent applies local quality by allowing the carbon nanotube distribution and orientation to vary locally across the roller surface. This creates regions with optimized surface roughness for ink holding while maintaining overall electrical conductivity. The nanocomposite structure allows different local zones to have slightly different properties while maintaining homogeneous electrical resistance across the entire roller surface.
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
The solution provides a more reliable and simpler method for fabricating impression rollers with improved electrical, mechanical, and thermal properties, ensuring consistent ink transfer and extended operational stability, reducing wear and overheating, and allowing operation at lower control tensions.
Implementation Method 1
said impression surface comprises a basic polymer matrix and an amorphous carbon and/or graphite and in which said impression surface comprises carbon nanotubes (CNT)
Implementation Method 2
The electrostatic load that is present on the surface of the impression roller makes it possible that capillary forces are overcome and the ink/colouring agent is completely transferred to the substrate
Implementation Method 3
as a consequence of the adhesion forces and/or capillary forces, the ink or colouring agent is not always completely transferred from the engraving holes to the substrate
Implementation Method 4
improved electrical, mechanical, and thermal properties
Data Source
AI summary
The present invention relates to rollers for industrial applications, such as impression rollers appropriate for ESA rotogravure. The invention relates to an impression roller that is appropriate for ESA rotogravure, in which the impression roller is provided with a stiff and essentially cylindrical roller core that is provided at its casing with an elastic and electrically guiding impression surface; in which said impression surface comprises a basic polymer matrix and an amorphous carbon and/or graphite and in which said impression surface comprises carbon nanotubes (CNT). In a second and third aspect, the invention relates to a method for fabricating a corresponding impression roller or roller casing. A fourth and fifth aspect of the invention relates to the use of an impression roller. A sixth aspect of the invention relates to a method for assembling a mix for fabricating an impression roller. A seventh aspect of the present invention relates to the use of carbon nanotubes in a roller surface belonging to an impression roller that is appropriate for ESA rotogravure. An eighth aspect relates to the use of carbon nanotubes in a roller element surface belonging to a roller element.