Polyether Paper Coating Deflocculant for pH-Independent Viscosity

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Solution Overview

Problem

Conventional paper coating compositions face challenges in maintaining stability and effectiveness across a wide pH range and high shear stress conditions, leading to issues with viscosity and particle flocculation, which affect printability and gloss.

Innovation Solution

The use of polyethers obtained by reacting diglycidyl ether with a water-soluble polyol containing polyoxyethylene chains, which act as deflocculants, water retention agents, and gloss enhancers, providing stability and improved performance regardless of pH and shear stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If conventional dispersing agents (complex phosphates, polyphosphoric acid salts, polycarboxylic acid salts) are used to reduce viscosity and maintain processing viscosity, then viscosity control is improved, but the composition becomes sensitive to pH value changes

Engineering Contradiction:

Improveviscosity stabilityVSAvoidpH independence

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent changes the chemical parameter of the dispersing agent from ionic compounds (phosphates, polyphosphoric acid salts, polycarboxylic acid salts) to non-ionic polyethers with polyoxyethylene chains. This parameter change eliminates pH sensitivity while maintaining viscosity control effectiveness, as the non-ionic polyether dispersing agents do not ionize and thus are not affected by pH variations in the coating composition.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conventional water retention agents (carboxymethyl cellulose) are used to prevent dewatering, then water retention is improved, but the composition becomes sensitive to pH value changes

Engineering Contradiction:

Improvewater retention performanceVSAvoidpH independence

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the ionic water retention agent carboxymethyl cellulose with non-ionic polyethers containing polyoxyethylene chains. This parameter change maintains water retention functionality while eliminating pH sensitivity, as the non-ionic polyether molecules do not ionize and thus their water retention performance remains consistent across different pH values.

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If conventional ionic substances are used in aqueous dispersions to improve optical brightening activation and water retention, then optical properties are improved, but effectiveness becomes dependent on pH value

Engineering Contradiction:

Improveoptical brighteningVSAvoidpH independence

Core Design Contradiction:

Illumination intensityVSAdaptability or versatility

Solution Approach 1:

The patent changes from ionic substances to non-ionic polyethers with polyoxyethylene chains. This parameter change maintains optical brightening effectiveness while eliminating pH dependency, as the non-ionic polyether molecules do not ionize and thus their optical properties remain consistent across different pH values.

Inventive Principle:

Principle #35Parameter changes

4Quantity of substance

If high solid contents are used in paper coating compositions to improve coating density, then coating quality is improved, but viscosity increases and processing becomes difficult

Engineering Contradiction:

Improvesolid contentVSAvoidprocessing viscosity

Core Design Contradiction:

Quantity of substanceVSEase of operation

Solution Approach 1:

The patent introduces non-ionic polyethers with polyoxyethylene chains as intermediary dispersing agents. These polyethers act as mediators between the high solid content and processing viscosity requirements, enabling the formulation of coatings with high pigment loads while maintaining manageable viscosity through the steric hindrance and solvation effects of the polyoxyethylene chains.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 polyether-based paper coating compositions exhibit stable viscosity and prevent particle flocculation, resulting in enhanced printability, brightness, and gloss, with improved water retention and rheological stability across different batches.

Implementation Method 1

specific polyethers containing polyoxyethylene chains... are suitable as deflocculants... the resulting paper coating compositions are stable over a wide viscosity range

Methodology Applied

Scientific EffectSteric hindrance:

Implementation Method 2

Water retention agents prevent dewatering of the coating composition upon contact with the surface of the paper sheet... the polyethers... act as... water retention agents

Methodology Applied

Scientific EffectHydrophilic interaction: Hydrophile

Implementation Method 3

the polyethers... act as... gloss enhancers... impart good printability and brightness to the coated paper

Methodology Applied

Scientific EffectSurface smoothing:

Implementation Method 4

Rheology modifiers are added to modulate the paper coating viscosity... the resulting paper coating compositions are stable over a wide viscosity range

Methodology Applied

Scientific EffectRheological control: Rheopecty

Data Source

PatentEP2616497B1Paper coating compositions

Publication Date: 2015.05.13 LAMBERTI SPA

AI summary

Paper coating compositions contain specific polyethers which are obtained by reacting a diglycidyl ether with a water soluble polyol containing at least one polyoxyethylene chain acting as deflocculants, water retention agents and gloss enhancers.