Amphiphilic Comb Polymers for High-Solids Paper Coating
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Solution Overview
Problem
Existing paper coating sauces face challenges in achieving optimal viscosity under low and high shear gradients, leading to issues with pumpability, filterability, and blade pressure during high-speed coating processes, while also experiencing water and water-soluble substance migration, which affects rheology and efficiency.
Innovation Solution
Development of amphiphilic comb polymers with a (meth)acrylic skeleton, containing hydrophobic and hydroxy or methoxy polyalkylene glycol monomers, partially or totally neutralized by neutralizing agents, which are non-water-soluble in acid form but become water-soluble upon neutralization, providing increased Brookfield viscosity and reduced ACAV viscosity, enhancing water retention and suitability for high solids and high-speed coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the solids content of the coating sauce is increased to improve productivity and coating quality, then the economic and qualitative advantages are achieved, but the shear viscosity increases leading to higher blade pressures and potential sauce overflows
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer additive, specifically using comb polymers with hydrophobic monomers (20-60% by weight) and polyalkylene glycol monomers (30-70% by weight) in specific ratios. This compositional parameter change allows the sauce to achieve high solids content (up to 35% dry extract) while maintaining controlled viscosity and blade pressure through the amphiphilic nature of the polymer
Solution Approach 2:
The patent employs composite polymer structures combining hydrophobic segments (styrene or C1-C4 acrylic esters) with hydrophilic polyalkylene glycol segments in a comb configuration. This composite material approach creates amphiphilic polymers that can interact with both water and organic components in the coating sauce, enabling high solids content formulations with optimized rheological properties and reduced blade pressure
2Ease of operation
If the Brookfield viscosity is increased to improve pumpability and prevent foaming, then the sauce handleability is improved, but the viscosity under high shear gradient also increases requiring higher blade pressures
Solution Approach 1:
The patent utilizes the dynamic rheological behavior of comb polymers that exhibit different viscosity responses under different shear conditions. The polymer structure provides pseudoplastic flow characteristics where viscosity decreases under high shear (coating) conditions while maintaining higher viscosity at low shear (pumping) conditions, enabling easy handling without excessive blade pressure
Solution Approach 2:
The patent optimizes the molecular weight and composition parameters of the comb polymer to achieve the desired rheological profile. By controlling the polymer architecture and monomer ratios, the sauce achieves optimal pumpability through increased low-shear viscosity while the high-shear viscosity remains controlled, preventing excessive blade pressure during coating application
3Ease of operation
If water-soluble polymers are used to increase Brookfield viscosity, then the handleability is improved, but the viscosity under high shear gradient increases leading to excessive blade pressure
Solution Approach 1:
The patent replaces conventional water-soluble polymers with amphiphilic comb polymers that have both hydrophobic and hydrophilic segments. This composite material approach creates a polymer that can associate through hydrophobic interactions while maintaining water solubility, resulting in enhanced low-shear viscosity without the excessive viscosity increase at high shear that characterizes conventional water-soluble polymers, thereby reducing blade pressure requirements
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
These polymers effectively increase Brookfield viscosity at low shear rates, reduce ACAV viscosity at high shear rates, and improve water retention, making them ideal for high-speed and high-solids coating processes without the drawbacks of prior art, such as excessive blade pressure and rheology changes.
Implementation Method 1
The polymer is amphiphilic, as it is rich in both hydrophobic monomer and polylakylene glycol monomer
Implementation Method 2
increasing the viscosity of sauces under low shear gradients and decreasing it under high gradients
Implementation Method 3
decreasing it under high gradients... viscosity under high shear gradient, as expressed by an ACAV viscosity value
Implementation Method 4
improving the water retention of said sauces... in which water and water-soluble substances migrate little within the sheet of paper
Data Source
AI summary
The invention consists of non-water-soluble comb-structured polymers having a (meth)acrylic backbone onto which are grafted side chains containing at least one hydrophobic monomer of the styrene or (meth)acrylic ester type in the C1 to C4 positions and at least one hydroxy or methoxy polyalkylene glycol monomer. The monomer contents are such that the polymer is amphiphilic, as it is rich in both hydrophobic monomer and polyalkylene glycol monomer. These products, used in paper coating slurries, increase Brookfield™ viscosity, decrease ACAV viscosity, and improve water retention, making them particularly well-suited for coatings with high solids content and/or high deposition rates.