Coated Paper Barrier Layer Using Saponified Polyvinyl Alcohol
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Solution Overview
Problem
Existing paper-based packaging materials face challenges such as inadequate barrier properties against oxygen, grease, and mineral oil, poor tear resistance, and non-recyclability due to high coating content and adhesive issues.
Innovation Solution
A coated paper comprising a base paper with a barrier layer made from at least partly saponified polyvinyl alcohol or its copolymers, which has an onset temperature of less than 210°C, enhancing barrier properties and recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyvinyl alcohol coating is applied to provide barrier properties against oil, grease, and oxygen, then barrier effect is improved, but water permeability increases due to hydrophilicity and swelling
Solution Approach 1:
The patent applies parameter changes by controlling the degree of saponification of polyvinyl alcohol within specific ranges (70-95% or 80-95%) to optimize the balance between barrier properties and water resistance. This chemical parameter adjustment modifies the polymer structure to reduce excessive hydrophilicity while maintaining effective barriers against oil, grease, and oxygen.
2Reliability
If high coating content is used to improve barrier properties, then barrier effect is enhanced, but recyclability deteriorates due to adhesive constituents and stickies formation
Solution Approach 1:
The patent reduces coating content to specific ranges (0.5-5 g/m² or 1-3 g/m²) while maintaining effective barrier properties through optimized polyvinyl alcohol formulations. This parameter optimization allows the packaging to remain recyclable in the paper cycle by minimizing adhesive constituents and preventing stickies formation that would interfere with recycling processes.
3Reliability
If conventional packaging materials are used to provide barrier properties, then barrier effect is achieved, but tear resistance and mechanical strength deteriorate
Solution Approach 1:
The patent creates a composite structure consisting of a paper or cardboard base material combined with a thin polyvinyl alcohol coating layer. This composite approach allows the bulk paper to provide mechanical strength and tear resistance, while the thin coating layer (0.5-5 g/m²) provides the necessary barrier properties against oxygen, grease, and mineral oil, achieving a synergistic combination of properties.
4Reliability
If polyvinyl alcohol coating is applied to improve barrier properties, then barrier effect is enhanced, but heat sealability and processability worsen due to high onset temperature
Solution Approach 1:
The patent modifies the thermal properties of polyvinyl alcohol by controlling the degree of saponification, which lowers the onset temperature and improves heat sealability. Additionally, the use of very thin coating layers (0.5-5 g/m²) reduces the thermal mass of the coating, enabling faster heating and cooling cycles that improve heat sealability and overall processability in packaging applications.
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 coated paper achieves improved oxygen, grease, and mineral oil barriers, increased tear resistance, and recyclability through the use of partly saponified polyvinyl alcohol, while maintaining compatibility with heat and cold sealing processes.
Implementation Method 1
the barrier layer comprising at least one polymer and being characterized in that the polymer comprises an at least partly saponified polyvinyl alcohol... improved oxygen, grease, and mineral oil barriers
Implementation Method 2
polyvinyl alcohols are very good at absorbing moisture, at swelling, and thus at creating pathways at molecular level through the barrier coating
Implementation Method 3
The ester groups in polyvinyl acetate can be alkaline saponified relatively easily, which converts the polymer into polyvinyl alcohol, making it hydrophilic and water-sensitive
Data Source
AI summary
The present invention relates to a coated paper comprising a base paper and a barrier layer applied thereto, the barrier layer comprising at least one polymer, the polymer comprising an at least partly saponified polyvinyl alcohol and/or an at least partly saponified polyvinyl alcohol copolymer, each of which has an onset temperature of less than 210° C. determined by DSC.