Structured Polymer Coating for Paper Machine Press Belt Water Management
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Solution Overview
Problem
Existing transfer and shoe press belts for paper machines lack efficiency in supporting high-speed paper webs, require improved production methods for extended service life, and struggle with embossing and water balance control.
Innovation Solution
A transfer or shoe press belt with a structured polymer coating on the paper or machine side, featuring a large number of elevations and depressions, applied using a spray or curtain coating process, and ground to maintain a textured surface for enhanced contact and water management, utilizing a reactive multi-component system with a viscosity suitable for processing temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a woven backing fabric with polymeric coating is used to ensure structural strength, then the belt can support high-speed paper webs, but the manufacturing process becomes complex and service life is limited
Solution Approach 1:
The belt combines a woven backing fabric carrier with a polymeric coating layer (polyurethane or polyurea) to create a composite structure. The carrier provides mechanical strength and flexibility for high-speed operation, while the coating layer provides surface properties for paper contact and water management. This composite approach resolves the contradiction by integrating multiple material functions into a single belt structure that can handle high speeds without excessive complexity.
2Adaptability or versatility
If grooves are introduced into the coating to create structure for embossing and water control, then embossing capability and water balance control are improved, but the manufacturing process becomes more difficult
Solution Approach 1:
The belt is provided with pre-formed grooves or channels in the polymeric coating layer before the belt enters service. These grooves can be created during the manufacturing process by molding or machining the coating layer. The preliminary structuring allows the belt to immediately provide embossing patterns and water drainage paths when put into operation, resolving the contradiction between versatility and manufacturing ease by preparing the structure in advance rather than requiring complex in-service adjustments.
3Reliability
If the coating is made smooth for good paper contact, then support for paper web is improved, but water drainage and embossing capability are reduced
Solution Approach 1:
The belt design incorporates both smooth areas and grooved areas in the polymeric coating layer. The smooth portions provide excellent contact with the paper web for reliable support and transfer, while the grooved portions provide channels for water drainage and embossing patterns. This local differentiation of surface quality resolves the contradiction by allowing different regions of the belt to perform different functions - smooth zones for paper contact and grooved zones for water management and embossing.
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 belt provides excellent support for high-speed paper webs, extends service life through protective polymer coatings, and enables effective embossing and water balance control, preventing 'aquaplaning' and ensuring efficient drainage.
Implementation Method 1
a structured top layer which is obtained in particular by applying the coating material by a spraying or curtain coating or extrusion process
Implementation Method 2
a coating material which is characterized by a viscosity of less than 3000 mPa s at a processing temperature in the range of 20°C to 120°C
Data Source
Figure 1~5
Figure 6~7
AI summary
The invention relates to a transfer or shoe press belt with a paper side (1) intended for the support of a paper or felt web and a machine side (2) facing away from the paper side, and with a carrier (3) and a structured cover layer (4) arranged on the paper side and/or machine side of the carrier (3), the cover layer consisting of or comprising at least one polymer, in particular polyurea and/or polyurethane, and which is characterized, at least on its side facing away from the carrier (3), by a structured surface with a plurality of protrusions (5) and depressions (6) and is ground on its side facing away from the carrier (3). Furthermore, the invention relates to a method for manufacturing a transfer or shoe press belt and the use of such a belt as a press belt, in particular a transfer or shoe press belt, in a paper machine.