Paper Substrate Barrier Coating via Degraded Starch
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Solution Overview
Problem
The paper and packaging industry seeks to increase the bio-based content of barrier coating compositions without compromising the barrier properties of paper substrates, specifically water and oil resistance, as existing solutions face challenges in achieving stable formulations with high polysaccharide and synthetic polymer combinations.
Innovation Solution
A water-based barrier coating composition is applied to paper substrates, comprising an aqueous polymer dispersion obtained by emulsion polymerization, with specific ratios of ethylenically unsaturated monomers and degraded starch, which enhances water and oil resistance without using ethylenically unsaturated acid monomers, ensuring stability and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high amounts of polysaccharides (such as starch) are combined with synthetic polymers in barrier coating compositions, then the bio-based content is increased, but the formulation stability deteriorates and the coating composition tends to separate
Solution Approach 1:
The patent applies parameter changes by carefully controlling the molecular weight of degraded starch (Mn = 500 to 30,000 Da) and adjusting the composition ratios of monomers and polysaccharides. This optimization prevents phase separation while maintaining high bio-based content, resolving the contradiction between increasing polysaccharide content and maintaining formulation stability.
Solution Approach 2:
The patent creates a stable composite material system combining synthetic polymers (acrylic polymers) with degraded starch through specific compositional ratios and controlled polymerization. This composite approach enables high bio-based content while preventing the separation issue that typically occurs when combining polysaccharides with synthetic polymers.
2Reliability
If traditional film-forming polymers derived from fossil resources are used, then the barrier properties are achieved, but the bio-based content is low
Solution Approach 1:
The patent changes the compositional parameters by replacing a portion of fossil-based polymers with degraded starch (Mn = 500 to 30,000 Da) while maintaining the barrier performance through optimized monomer selection and polymerization conditions. This enables increased bio-based content without compromising barrier properties.
Solution Approach 2:
The patent applies local quality by using different materials for different functional requirements: degraded starch provides bio-based content and barrier properties, while specific monomers (styrene, alkyl acrylates) provide film-forming characteristics and stability. This localized functional assignment allows high bio-based content while maintaining reliable barrier performance.
3Ease of manufacture
If ethylenically unsaturated acid monomers are used in the polymerization, then the polymerization can proceed, but the coating composition becomes unstable and separates
Solution Approach 1:
The patent extracts (removes) ethylenically unsaturated acid monomers from the polymerization system while maintaining polymerization feasibility through alternative monomer combinations (styrene, alkyl acrylates, cycloalkyl acrylates). This elimination of acid monomers prevents coating composition separation and maintains stability.
Solution Approach 2:
The patent introduces degraded starch as an intermediary substance that mediates between the synthetic polymer components and the polysaccharide content. The degraded starch with specific molecular weight (Mn = 500 to 30,000 Da) acts as a stabilizing agent that prevents phase separation while allowing the polymerization to proceed with non-acid monomers.
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 effectively increases the bio-based content of barrier coatings while maintaining or improving water and oil resistance, as demonstrated by the stability and performance of the aqueous polymer dispersions in various examples, showing enhanced resistance without adverse effects on the paper substrate.
Implementation Method 1
an aqueous polymer dispersion having a solids content from 20 to 50 wt % and obtained by emulsion polymerization of: a) from 0 to 40% by weight of at least one ethylenically unsaturated monomer selected among styrene or substituted styrene, b) from 15 to 55% by weight of at least one ethylenically unsaturated monomer selected among C1-C10-alkyl (meth)acrylates or cycloalkyl (meth)acrylates, in the absence of ethylenically unsaturated acid monomers and in the presence of c) from 45 to 80% by weight of degraded starch
Data Source
AI summary
A method for improving the water and/or oil resistance of a paper substrate comprising: i) providing a paper substrate; ii) applying to the paper substrate a water-based barrier coating composition having a solids content from 10 to 55 wt % (% by weight) and comprising from 50 to 95 wt % of an aqueous polymer dispersion having a solids content from 20 to 50 wt % and obtained by emulsion polymerization of: a) from 0 to 40% by weight of at least one ethylenically unsaturated monomer selected among styrene or substituted styrene, b) from 15 to 55% by weight of at least one ethylenically unsaturated monomer selected among C1-C10-alkyl (meth)acrylates or cycloalkyl (meth)acrylates, in the absence of ethylenically unsaturated acid monomers and in the presence of c) from 45 to 80% by weight of degraded starch having a molecular weight Mn of 500 to 30,000 Da.