High-Molecular-Weight GPAM–CMC Composition for Alkaline Paper Dry Strength
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Solution Overview
Problem
Existing reactive strength resins like GPAM are ineffective in high pH and alkalinity conditions, particularly with precipitated calcium carbonate fillers, and do not provide sufficient dry strength enhancement for certain paper grades, leading to issues in repulping and dispersibility.
Innovation Solution
A composition combining high molecular weight cationic glyoxalated polyacrylamide (GPAM) with an anionic polysaccharide promoter, such as carboxymethylcellulose (CMC), is used to enhance dry strength in paper products, providing improved tensile strength, resistance to rupture, and resistance to compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If GPAM is used to enhance paper wet strength through covalent bonds, then wet strength is improved, but repulping and dispersibility become difficult requiring excessive mechanical force or harsh chemicals
Solution Approach 1:
The patent changes the molecular weight parameter of GPAM from conventional low molecular weight (below 25,000 Da) to high molecular weight (above 50,000 Da, preferably 100,000-1,000,000 Da). This parameter change modifies the balance between wet strength and repulping properties, providing sufficient wet strength while improving repulping and dispersibility compared to conventional low molecular weight GPAM
2Strength
If GPAM is used to increase dry strength, then dry strength is enhanced, but performance is adversely affected by high pH and high alkalinity levels above 8.0 and 200 ppm respectively
Solution Approach 1:
The patent changes the molecular weight parameter of GPAM to high molecular weight (above 50,000 Da, preferably 100,000-1,000,000 Da), which improves performance under high pH and alkalinity conditions compared to conventional low molecular weight GPAM. The high molecular weight structure provides better stability and effectiveness in challenging paper machine conditions with PCC filler and recycled pulp
3Ease of manufacture
If low molecular weight GPAM (below 25,000 Da) is used, then the polymer structure is simpler and easier to manufacture, but insufficient dry strength enhancement is achieved for certain paper grades
Solution Approach 1:
The patent changes the molecular weight parameter from low (below 25,000 Da) to high (above 50,000 Da, preferably 100,000-1,000,000 Da). This parameter change directly addresses the insufficient dry strength enhancement problem while maintaining manufacturability through established glyoxalation processes applied to high molecular weight cationic polyacrylamide base polymers
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 combination of high molecular weight GPAM and CMC significantly enhances dry strength properties in paper products, offering increased tensile strength, burst resistance, and tear resistance compared to lower molecular weight GPAM systems.
Implementation Method 1
Upon drying of the treated paper sheet, GPAM is believed to form covalent bonds with paper cellulose to increase paper dry strength
Implementation Method 2
a cationic glyoxalated polyacrylamide ('GPAM') comprising a high molecular weight base polymer and at least one anionic polysaccharide promoter ('APP') for enhancing the strength of paper and board
Data Source
AI summary
Compositions and processes for strengthening paper products are provided. The inventive compositions comprise a combination at least one cationic glyoxalated polyacrylamide (“GPAM”) comprising a high molecular weight base polymer and at least one anionic polysaccharide promoter (“APP”). The inventive process for manufacturing paper products with enhanced dry strength properties comprises adding to a fiber stock comprising cellulosic fibers at least one cationic glyoxalated polyacrylamide (“GPAM”) comprising a high molecular weight base polymer; and at least one anionic polysaccharide promoter (“APP”).