Wet-Shrink Paper Packaging for Heat-Free Article Binding
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Solution Overview
Problem
Plastic shrink-wrap is unsustainable and requires high heat for shrinking, while paper lacks the ability to shrink upon heating, limiting its use as a versatile packaging material for irregularly shaped articles.
Innovation Solution
A paper packaging material with at least 3% wet shrinkage in the CD direction, enhanced by long fibers and high wet tensile strength, is used to wrap articles by wetting and drying, allowing shrinkage around the articles without heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plastic shrink-wrap is used, then the packaging material shrinks around products when heated providing tight binding, but the process requires high heat and generates CO2
Solution Approach 1:
The patent changes the physical state parameter of the packaging material from dry to wet, enabling shrinkage without heat. The paper packaging material is wetted before wrapping, allowing it to shrink around products through evaporation of water rather than thermal heating, thus eliminating the need for high temperature while maintaining binding strength
Solution Approach 2:
The patent replaces the thermal heating mechanism with a moisture-based mechanism. Instead of using heat to cause plastic shrinkage, the invention uses water absorption and evaporation to cause paper shrinkage, substituting a mechanical/chemical process for a thermal one, thereby reducing energy consumption and CO2 emissions
2Object-generated harmful factors
If paper packaging is used, then the material is sustainable and requires no heat, but the paper lacks shrinkage ability when wetted
Solution Approach 1:
The patent modifies the physical parameters of the paper packaging material by controlling fiber length (at least 1.5mm, preferably at least 2mm) and wet tensile strength (at least 10% of dry tensile strength). These parameter changes enable the paper to shrink effectively when wetted while maintaining structural integrity, giving it the shrinkage capability previously only achievable with plastic
Solution Approach 2:
The patent creates a composite paper packaging material with specific properties that combine sustainability with shrinkage capability. The material uses long fibers and controlled wet strength characteristics to achieve both environmental benefits and functional performance, effectively merging the advantages of biodegradability with shrink-wrap functionality
3Adaptability or versatility
If paper is wetted to enable shrinkage, then the material can bind articles, but the wet paper may tear due to reduced strength
Solution Approach 1:
The patent carefully controls the wet tensile strength parameter to be at least 10% of the dry tensile strength. This parameter optimization ensures that the paper maintains sufficient strength when wetted to prevent tearing during wrapping and shrinking, while still achieving the necessary shrinkage for binding articles tightly
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 paper packaging material effectively binds and holds articles together, providing a sustainable alternative to plastic shrink-wrap with reduced energy consumption.
Implementation Method 1
Paper is sensitive to humidity. A change in the humidity will result in a (anisotropic) dimensional change of the paper... the inventors have selected paper properties to enhance dimensional instability of the paper to select a paper packaging material that preferentially maximises expansion and contraction of the paper upon wetting and subsequent drying
Implementation Method 2
The packaging material may be dried by blowing unheated air over the packaging. Alternatively the packaging material is dried by the application of heat or blowing heated air over the packaging
Data Source
AI summary
The present invention provides a packaging material comprising paper having a wet shrinkage in the CD direction of at least 3% and a method of wrapping articles with said packaging material, wetting the packaging material, wrapping said articles with said wetted packaging material, and drying the packaging material such that it shrinks to tightly bind the wrapped articles.