Paper Forming with Post-Shear GPAM Addition for Dry Strength
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Solution Overview
Problem
Existing papermaking processes using glyoxalated polyvinylamides for dry strength additives require addition before high shear operations, leading to high costs and limited shelf life, while not maximizing dry strength in paper products.
Innovation Solution
Addition of a glyoxalated polyvinylamide adduct (GPAM) after the last high shear operation and before the headbox in the papermaking process, allowing for comparable or greater dry strength with reduced amounts, enhancing process flexibility and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glyoxalated polyvinylamide is added to thick stock before high shear operation, then dry strength is maximized, but polymer cost and production cost increase
Solution Approach 1:
The patent applies preliminary action by pre-reacting polyvinylamide with glyoxal to form a reactive adduct before papermaking. This pre-prepared adduct then interacts with cellulosic fibers during the papermaking process, achieving maximized dry strength with reduced polymer dosage compared to direct addition of unmodified polyvinylamide.
Solution Approach 2:
The patent changes the chemical parameter of the polymer by modifying polyvinylamide with glyoxal to create a reactive adduct. This chemical modification enables the polymer to form stronger bonds with cellulosic fibers, thereby maximizing dry strength while reducing the required polymer concentration from typical levels to optimized levels.
2Strength
If glyoxalated polyvinylamide is added to thick stock, then dry strength is maximized, but shelf life is limited
Solution Approach 1:
The patent performs preliminary reaction between polyvinylamide and glyoxal to create a stable adduct that can be stored. This pre-reacted adduct has extended shelf life compared to unmodified polyvinylamide, while maintaining the ability to provide maximized dry strength when applied to cellulosic fibers during papermaking.
3Ease of operation
If high shear operation is performed before polymer addition, then mixing is improved, but polymer degradation occurs
Solution Approach 1:
The patent applies preliminary action by pre-forming the polyvinylamide-glyoxal adduct before the high shear mixing operation. This pre-formed adduct is then added to the diluted stock after high shear mixing has occurred, avoiding degradation while still achieving effective distribution and interaction with cellulosic fibers.
Solution Approach 2:
The patent inverts the conventional sequence by first performing high shear mixing to prepare the stock, then adding the pre-formed adduct. This reversal protects the polymer structure from high shear degradation while maintaining mixing efficiency for uniform distribution.
4Productivity
If glyoxalated polyvinylamide is added to thin stock, then drainage and retention improve, but dry strength is reduced
Solution Approach 1:
The patent changes the chemical parameter of the polymer adduct to optimize its interaction with cellulosic fibers. The modified adduct maintains improved drainage and retention characteristics when added to thin stock, while also achieving maximized dry strength through enhanced bonding with fibers, resolving the trade-off between drainage performance and strength development.
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 dry strength in paper products with minimized GPAM usage, improving process efficiency and reducing costs.
Implementation Method 1
The aqueous composition comprises an adduct formed from the reaction of glyoxal and a polyvinylamide prepolymer
Implementation Method 2
subjecting the diluted aqueous suspension to a high shear operation
Data Source
AI summary
Methods of forming paper products are provided herein. A method comprises providing an aqueous suspension of cellulosic fibers; diluting the aqueous suspension with water to form a diluted aqueous suspension having a solids content from about 0.3 wt % to about 1.8 wt %, based on a total weight of the diluted aqueous suspension; subjecting the diluted aqueous suspension to a high shear operation; adding an aqueous composition comprising an adduct formed from the reaction of glyoxal and a polyvinylamide prepolymer to the diluted aqueous suspension; forming the diluted aqueous suspension into a sheet; and drying the sheet. The aqueous composition is added after the diluted aqueous suspension is subjected to the high shear operation and before the diluted aqueous suspension is passed to a headbox. The method is free of any high shear operation after the aqueous composition is added and before the diluted aqueous suspension is passed to the headbox.