Soft Roll Starch Application for Fiber Web Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The deteriorating quality of waste paper fibers used in producing testliner and corrugated medium papers due to increased recycling cycles leads to reduced strength properties, necessitating an efficient method to enhance web strength while maintaining economic viability.
Innovation Solution
A method involving the application of starch to a moving fiber web using rolls with a hardness of 15 P&J or lower, utilizing slot or slide dies for precise starch transfer, ensuring uniform distribution and avoiding wear issues, with adjustable starch properties and nip load to optimize strength enhancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If starch is applied using conventional soft rolls (hardness > 20 P&J) in a size press, then the starch can be applied to the fiber web, but the starch transfer efficiency is insufficient and web strength is not adequately enhanced
Solution Approach 1:
The patent changes the physical parameter of roll hardness from conventional soft rolls (>20 P&J) to hard rolls (15 P&J or lower, preferably 5-12 P&J). This parameter change enables more effective starch transfer to the web surface while maintaining roll durability and consistent performance under high lineload conditions.
2Productivity
If the roll hardness is increased to improve starch transfer, then starch application efficiency improves, but the rolls may experience increased wear and reduced service life
Solution Approach 1:
The patent optimizes the roll hardness parameter to a specific range (15 P&J or lower, preferably 5-12 P&J) that balances starch transfer efficiency with roll durability. This optimized parameter enables effective starch application while minimizing wear, allowing the rolls to maintain performance over extended service periods.
3Strength
If the lineload in the treatment nip is reduced to protect the rolls, then roll wear decreases, but the starch transfer to the web becomes insufficient
Solution Approach 1:
The patent changes the roll hardness parameter to enable operation at higher lineloads (30-140 kN/m, preferably 60-120 kN/m) without excessive wear. The harder rolls can withstand these increased forces, allowing sufficient starch transfer to occur under high compression conditions that match modern high-speed production requirements.
4Speed
If conventional soft rolls are used in the size press, then the rolls are durable, but the starch cannot be transferred efficiently to the fiber web at high production speeds
Solution Approach 1:
The patent changes the roll hardness to match the demands of high-speed production. The harder rolls (15 P&J or lower) maintain their shape and surface properties under high-speed operating conditions, ensuring consistent starch transfer efficiency even at production speeds exceeding 1000 m/min where soft rolls would deform and lose effectiveness.
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 effectively increases the strength of the fiber web, stabilizes production, and reduces downtime by ensuring efficient starch application and distribution, even at high production speeds, thereby improving the quality of testliner and corrugated medium papers.
Implementation Method 1
The starch is applied first to the first roll and/or the second roll via a slot die and/or a slide die and then transferred to the fiber web in the treatment nip
Implementation Method 2
the fiber web is passed through a treatment nip formed by the first roll and the second roll
Implementation Method 3
The deteriorated fiber quality, e.g. the reduced fiber length, can be partially compensated by the treatment of the fiber web with synthetic binders like polymer-latex. Alternatively, the fiber web can be treated with natural binders like starch
Data Source
AI summary
A method and a device for the application of starch on a moving fiber web, especially on a packaging paper web such as a testliner or a corrugated medium web, include first applying starch to a first roll and/or a second roll and passing the fiber web through a treatment nip formed by the first roll and the second roll. At least one of the first or the second roll, preferably both rolls, have a hardness of 15 P&J (Pusey & Jones) or lower, preferably 5 P&J or lower and most preferably 1 P&J or lower. The starch is applied to the first roll and/or the second roll by a slot die and/or a slide die and then transferred to the fiber web in the treatment nip.