Multi-Ply Paperboard Couching Without Starch Bonding
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Solution Overview
Problem
Existing methods for producing multi-ply paperboards face challenges in achieving high strength and cost-effectiveness, particularly in the bond strength between plies, and there is a need for optimization in the production process.
Innovation Solution
A method involving the spraying of water substantially free from bonding chemicals like starch onto the surfaces of paperboard plies in a full-scale paperboard machine, followed by couching to merge the plies without external heat, enhancing mechanical properties such as z-directional tensile strength and internal bond strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bonding chemicals like starch are used to bond plies together, then bond strength between plies is improved, but production cost increases
Solution Approach 1:
The invention extracts and removes bonding chemicals (starch) from the multi-ply paperboard production process. By eliminating the starch application step and relying solely on mechanical couching pressure and fiber-to-fiber bonding, the process achieves adequate bond strength without the added cost of chemical bonding agents, directly resolving the contradiction between bond strength and production cost
Solution Approach 2:
The paperboard plies bond to each other through their own inherent properties - the fibers naturally interlock and bond under the couching pressure without requiring external bonding chemicals. The system uses its own materials (cellulose fibers) to achieve the bonding function, eliminating the need for starch and reducing production costs while maintaining acceptable bond strength
2Strength
If water is sprayed onto ply surfaces before couching, then z-directional tensile strength is enhanced, but production process complexity increases
Solution Approach 1:
The invention changes the moisture parameter of the ply surfaces by spraying water before couching. This moisture adjustment optimizes the bonding characteristics during the couching process, enhancing z-directional tensile strength. The parameter change is simple and direct - adding water to modify surface properties for better bonding, without requiring complex process changes
Solution Approach 2:
Water is sprayed onto the ply surfaces in advance of the couching operation. This preliminary wetting action prepares the fiber surfaces for optimal bonding during couching by adjusting moisture content before the plies are pressed together. The preparation is done beforehand, simplifying the overall process while achieving the desired strength enhancement
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 method achieves comparable or improved mechanical properties without the use of bonding chemicals, reducing production costs and maintaining or enhancing z-directional tensile strength and internal bond strength.
Implementation Method 1
spraying water substantially free from bonding chemicals onto a surface of the first ply web or second ply web to obtain a wetted surface
Implementation Method 2
merging the wetted surface with a surface of the other web by couching
Data Source
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AI summary
There is provided a method of forming a multi-ply paperboard comprising at least a first ply and a second ply in a full-scale paperboard machine, wherein the method comprises the following steps: - forming a first ply web and a second ply web in a wire section of the paperboard machine; - spraying water substantially free from bonding chemicals onto a surface of the first ply web or second ply web to obtain a wetted surface in the wire section; and - merging the wetted surface with a surface of the other web by couching.