Grafted Polyvinyl Alcohol Polymer for Re-pulpable Tissue
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Solution Overview
Problem
Conventional papermaking additives that enhance wet strength and water repellency lead to issues during recycling, as they form hydrophilic residues that re-agglomerate in paper mills, causing clogs and hindering water dispersibility, which is crucial for both wet applications and recycling processes.
Innovation Solution
A novel grafted polyvinyl alcohol polymer with a balanced hydrophilicity and hydrophobicity, comprising a polyvinyl alcohol main chain and side chains of aliphatic monocarboxylic acid, dicarboxylic acid, and reactive quaternary ammonium salt units, which provides temporary water repellency and water absorption delay properties, allowing for easy water dispersibility and recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polymer additives are used to improve wet strength and water repellency, then wet strength and water repellency are improved, but the paper becomes difficult to disperse in water during recycling
Solution Approach 1:
The patent changes the chemical parameters of the polymer additive by controlling the degree of hydrolysis of polyvinyl alcohol (specifically 74-88%) and grafting specific monomers (aliphatic monocarboxylic acid, dicarboxylic acid, and reactive quaternary ammonium salt). These parameter changes enable the polymer to provide wet strength while maintaining water dispersibility during recycling, resolving the contradiction between improved wet strength and ease of water dispersal.
2Object-affected harmful factors
If conventional polymer additives are used to provide water repellency, then water repellency is improved, but hydrophilic residues form during recycling that cause clogs
Solution Approach 1:
The patent modifies the chemical composition parameters of the polymer by selecting specific monomers with appropriate hydrophobic-hydrophilic balance. The combination of aliphatic monocarboxylic acid, dicarboxylic acid, and reactive quaternary ammonium salt grafts onto polyvinyl alcohol creates a polymer that provides temporary water repellency without leaving problematic hydrophilic residues during recycling.
Solution Approach 2:
The patent creates a composite polymer structure by grafting multiple different monomer types onto the polyvinyl alcohol backbone. This composite structure combines the water repellency properties of hydrophobic groups with the solubility and dispersibility properties of carboxylic acid and quaternary ammonium groups, achieving water repellency without residue formation.
3Strength
If covalent bonding additives are used to attach to paper fibers, then wet strength is improved, but the additives prevent re-pulping and recycling
Solution Approach 1:
The patent changes the bonding mechanism parameter from permanent covalent bonds to temporary electrostatic and hydrogen bonding interactions. By controlling the degree of hydrolysis and selecting specific ionic groups (carboxylic acid and quaternary ammonium salt), the polymer forms strong temporary bonds that provide wet strength but can be easily broken during re-pulping, enabling recycling.
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 polymer enhances wet and dry tensile strength while ensuring complete dispersion in water, preventing clogs and facilitating recycling by converting from a solid to a water-dispersible state, thus addressing the limitations of existing additives.
Implementation Method 1
A novel grafted polyvinyl alcohol polymer that is a fine-tuned balance between hydrophilicity and hydrophobicity
Implementation Method 2
A novel grafted polyvinyl alcohol polymer that is a fine-tuned balance between hydrophilicity and hydrophobicity
Implementation Method 3
resin that is water dispersible and easily adsorbed onto cellulosic substrates
Implementation Method 4
allowing for easy water dispersibility and recyclability
Data Source
AI summary
A grafted polyvinyl alcohol polymer has a balance between hydrophilicity and hydrophobicity. The grafted polyvinyl alcohol polymer has a chemical functionality that allows for adsorption onto the pulp fibers, polymer film formation upon drying, repelling water upon wetting, polymer film swelling and breaking for prolonged wetting by water. When incorporated into paper products, the polymer can provide a paper having improved wet strength, temporary water repellency, and/or is dispersible in aqueous solutions.