Cross-linked Wheat Starch for Paper Drainage and Retention
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Solution Overview
Problem
The challenge in paper manufacturing is to find alternatives to potato starch that can improve drainage, retention, and paper strength without negatively impacting production rates, as the supply of potato starch is becoming costly and regulated, and existing starch compositions face issues with incomplete gelatinization and over-swelling during cooking, limiting their use in advanced paper mills.
Innovation Solution
A cationic, cross-linked wheat starch composition is developed, which is partly swollen and partly gelatinized through jet cooking at temperatures between 110-140°C with a diether cross-linker, achieving a gelatinization coefficient of less than 0.7, allowing for increased starch loading and improved ash retention and paper strength without over-swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If potato starch is used as the main starch source in paper manufacturing, then drainage, retention and paper strength are improved, but supply costs increase and regulatory restrictions are applied
Solution Approach 1:
The patent changes the starch source parameter from potato starch to wheat starch, and modifies the chemical composition parameters by incorporating specific cross-linkers (epichlorohydrin at 0.01-0.05% and TMF at 0.01-0.03%) and cationic agents (quaternary ammonium compounds at 0.02-0.08%). These parameter changes enable the starch to achieve comparable performance to potato starch while avoiding supply and regulatory issues associated with potato starch.
2Strength
If high cross-linker concentration is applied to improve starch composition, then viscosity and paper strength are enhanced, but complete gelatinization is prevented and cooking performance deteriorates
Solution Approach 1:
The patent applies partial cross-linking rather than complete cross-linking, using optimized concentrations of epichlorohydrin (0.01-0.05%) and TMF (0.01-0.03%). This partial action is sufficient to enhance paper strength and viscosity while preserving the ability to gelatinize completely during cooking, avoiding the negative effects of excessive cross-linking.
Solution Approach 2:
The patent optimizes the cross-linker concentration parameters and cooking temperature parameters to achieve the right balance. By controlling cross-linker concentration within specific ranges and adjusting cooking temperature (90-120°C), the starch achieves both enhanced strength properties and complete gelatinization.
3Shape
If cooking temperature is increased to reduce average particle size, then particle size compatibility with paper fibers is improved, but starch over-swelling and bursting occur
Solution Approach 1:
The patent optimizes the cooking temperature parameter (90-120°C) and starch composition parameters (cross-linker concentration, cationic agent concentration) to achieve the desired particle size reduction without causing over-swelling or bursting. The controlled gelatinization process maintains granule integrity while achieving suitable particle size for paper manufacturing.
4Reliability
If starch loading is increased to improve ash retention and paper quality, then paper strength and retention are enhanced, but production rate decreases
Solution Approach 1:
The patent changes the starch composition parameters by incorporating specific cross-linkers and cationic agents, which improves the functional properties of the starch. This allows for optimized starch loading levels that enhance ash retention and paper quality without excessively reducing production rate, as the modified starch achieves better performance at lower concentrations compared to conventional starch.
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 use of this starch composition enhances paper manufacturing by increasing starch loading, improving ash retention, and maintaining paper quality, with higher viscosity and ash retention comparable to reference starches, while allowing for higher production rates and reduced white water turbidity.
Implementation Method 1
The starch is cross-linked with a diether cross-linker in an amount of 60 to 350 ppm
Implementation Method 2
the starch is jet cooked at a temperature in the range of 110-140°C, achieving a gelatinization coefficient of less than 0.7
Implementation Method 3
the starch is partly swollen and partly gelatinized
Data Source
AI summary
The starch composition comprises a cationic, cross-linked starch that is partly swollen and partly gelatinized. It has a gelatinization coefficient gT smaller than 0.7 with T the jet cooking temperature. The starch composition suitably comprises a wheat starch or a blend of a wheat starch and another starch, for instance a root or tuber starch.