Wood Bark Barrier Coating for Moisture-Resistant Paper

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Solution Overview

Problem

Traditional water-based barrier coatings for fibrous products, which rely on petrochemistry-based binders, are not environmentally desirable and natural polymer alternatives are moisture-sensitive, limiting their use in applications like food packaging.

Innovation Solution

A barrier coating layer comprising a wood bark-derived component, such as suberin or betulin, with a fiber content less than 40% of the dry weight, combined with pigments and binders, providing a thin, breathable, and moisture-resistant layer for fibrous substrates like paper and paperboard.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If natural polymers are used to replace petrochemistry-based binders, then environmental sustainability is improved, but moisture resistance deteriorates

Engineering Contradiction:
Improveenvironmental sustainabilityVSAvoidmoisture resistance
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent uses a composite coating composition combining natural polymer binders (starch, cellulose, hemicellulose) with wood bark-derived extractives (suberin, betulin, procyanidins) and optional inorganic pigments. This composite approach allows the natural polymers to provide environmental sustainability while the wood bark components contribute moisture barrier properties, resolving the contradiction between eco-friendliness and moisture resistance.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical composition parameters of the coating by incorporating specific wood bark-derived components containing suberin, betulin, and procyanidins. These components change the physical and chemical parameters of the natural polymer matrix, enhancing its moisture barrier properties without compromising its biodegradability and environmental sustainability.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If fiber content in barrier coating layer is reduced below 40%, then moisture barrier performance is improved, but coating strength deteriorates

Engineering Contradiction:
Improvemoisture barrier performanceVSAvoidcoating strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent creates a composite coating system where low fiber content (below 40%) is compensated by the synergistic interaction between natural polymer binders and wood bark-derived extractives. The suberin, betulin, and procyanidins from wood bark form a dense, hydrophobic matrix that provides both moisture barrier performance and mechanical strength, eliminating the need for high fiber content.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent concentrates the moisture barrier functionality in specific regions of the coating matrix where wood bark-derived components (suberin, betulin) are present, rather than relying on uniform fiber distribution. This local concentration of hydrophobic components creates effective moisture barrier zones even with low overall fiber content, while the natural polymer binder maintains overall coating integrity.

Inventive Principle:
Principle #3Local quality

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 solution achieves enhanced moisture and water vapor resistance with a thin, breathable coating, allowing for effective gas transmission while using renewable components, even in small amounts of wood bark-derived materials, suitable for packaging applications.

Implementation Method 1

The barrier coating layer comprises a wood bark-derived component... providing resistance to grease, moisture or oxygen... enhanced moisture and water vapor resistance

Methodology Applied
Scientific EffectHydrophobicity: Hydrophobe

Implementation Method 2

The barrier coating layer is breathable or porous... allowing for effective gas transmission

Methodology Applied
Scientific EffectPermeation: Permeation

Data Source

PatentUS20240392509A1A fibrous product and a method of coating a fibrous substrate
Publication Date: 2024.11.28 METSA BOARD

AI summary

According to an example aspect of the present invention, there is provided a fibrous product comprising a barrier coating layer, wherein the barrier coating layer comprises a wood bark-derived component, and a fiber content, particularly cellulosic fiber content, of the barrier coating layer is less than 40% of the dry weight of the layer.