Mineral-Filled Paper Coating for Recyclable Flexible Packaging
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Solution Overview
Problem
Current paper packaging materials, particularly those used in flexible packaging, face challenges with permeability to oils, fats, and gases, leading to compromised mechanical properties and difficulty in recycling due to the use of plastic coatings, which are not biodegradable and require significant industrial adaptations.
Innovation Solution
A paper composition comprising 60-95% short fibers, 2-15% mineral load, and additional components like modified starch and polyvinyl alcohol for sealing, providing good mechanical properties and barrier against fats, suitable for biodegradation and composting, and applicable in existing machinery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plastic-based coatings are used on paper to provide barrier and sealing properties, then the packaging achieves good barrier against oils, fats, and gases, but the packaging becomes difficult to recycle and separate polymers from fibers
Solution Approach 1:
The invention extracts the harmful plastic coating component from the paper packaging system and replaces it with a mineral-based coating (calcium carbonate). This extraction eliminates the recycling problem while maintaining the necessary barrier properties through the mineral coating and optimized fiber composition.
Solution Approach 2:
The invention changes the chemical composition parameters of the coating from organic polymers to inorganic mineral materials (calcium carbonate). This parameter change transforms the material from non-recyclable plastic to recyclable mineral coating, while the specific particle size and concentration parameters are optimized to maintain barrier effectiveness.
2Adaptability or versatility
If paper is used to replace plastic in flexible packaging, then the packaging becomes biodegradable and compostable, but the paper lacks sufficient mechanical strength, flexibility, and tensile strength
Solution Approach 1:
The invention creates a composite paper material by combining short wood fibers (60-95%) with mineral load (2-15%, specifically calcium carbonate). This composite structure provides both the biodegradability of natural fibers and the mechanical strength enhancement from the mineral reinforcement, achieving properties comparable to plastic films.
Solution Approach 2:
The invention applies local quality enhancement by adding mineral load specifically to reinforce the paper structure where mechanical strength is needed, while maintaining the natural biodegradable character of the fiber matrix. The mineral particles are distributed to provide localized reinforcement without compromising the overall biodegradability.
3Ease of manufacture
If paper with low mechanical strength is used, then the paper can be manufactured with current technology, but the paper is thicker than plastic films and cannot be shaped without causing fiber cracks and loss of strength
Solution Approach 1:
The invention changes the physical parameters of the paper by incorporating mineral load, which increases mechanical strength and reduces thickness. The calcium carbonate particles reinforce the fiber network, allowing the paper to achieve plastic-film-like thickness while maintaining structural integrity during shaping operations.
Solution Approach 2:
The composite paper structure with mineral reinforcement allows the material to be thinner and more flexible than conventional low-strength papers, enabling it to be shaped without fiber cracks while remaining manufacturable with current papermaking technology.
4Strength
If short fibers are used in paper composition, then the paper achieves good mechanical properties and printability, but the paper permeability to oils and fats increases
Solution Approach 1:
The invention uses a composite structure combining short fibers with mineral load (calcium carbonate) to address the permeability issue. The mineral particles fill the spaces between fibers and create a more dense structure that reduces oil and fat permeation, while the short fiber composition maintains mechanical strength and printability.
Solution Approach 2:
The mineral load is distributed throughout the paper structure to locally enhance barrier properties against oils and fats, while the short fiber matrix maintains the mechanical properties and surface quality needed for printing. The local reinforcement with mineral particles creates barrier pathways without compromising overall mechanical performance.
Data Source
Figure 1~2
AI summary
The present invention relates to a paper comprising short fibres and a mineral filler. The paper of the present invention has good mechanical properties, good printability and recyclability. A coated paper is also described, comprising the paper of the invention and a barrier composition. Coated paper also has good sealing properties and a grease barrier. Paper packaging comprising the paper or coated paper of the present invention is also disclosed, wherein the packaging is biodegradable and compostable. The use of paper or coated paper for application in primary and secondary flexible packaging is also described. A method for obtaining the paper and a method for manufacturing the coated paper of the present invention are also disclosed.