Polymer Blends with Natural Wax for Low Water Vapor Permeability
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Solution Overview
Problem
Existing polymer films used in food packaging do not provide a sufficient water vapor barrier, with permeability levels exceeding the requirements for many applications, particularly requiring a barrier of less than 500 g·μm·m²·d⁻¹.
Innovation Solution
A polymer mixture comprising 98-99.99% of a polycondensate derived from α,ω-C18-C30 dicarboxylic acids or their derivatives and α,ω-C2-C30 diols, combined with 0.01-2% natural wax, which is synthesized through direct polycondensation and further processed to achieve low water vapor permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional polymer films are used for food packaging, then they provide basic packaging functionality, but they do not provide sufficient water vapor barrier (permeability exceeds 500 g·μm·m²·d⁻¹)
Solution Approach 1:
The patent combines polycondensates derived from long-chain dicarboxylic acids (C18-C30) and diols (C2-C30) with natural waxes to create a composite material system. This composite structure leverages the complementary properties of both components: the polycondensate provides structural integrity while the natural wax fills intermolecular spaces and reduces free volume, achieving water vapor permeability below 200 g·μm·m²·d⁻¹ that satisfies food packaging requirements
2Object-affected harmful factors
If beeswax is added to starchy, short-chain polyesters, then water vapor barrier improves to 1600-5700 g·μm·m⁻², but the polymer chain structure remains short-chain with limited inherent barrier properties
Solution Approach 1:
The patent fundamentally changes the polymer chain structure by using long-chain dicarboxylic acids (C18-C30) and diols (C2-C30) as monomers, creating polycondensates with extended molecular chains. This structural parameter change increases chain flexibility and reduces crystallinity, creating more free volume that can be effectively filled by natural wax additives, thereby achieving superior water vapor barrier properties compared to short-chain polyesters
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 polymer mixture achieves a significantly lower water vapor permeability, meeting the requirements for food packaging applications with permeability levels below 200 g·μm·m²·d⁻¹, enhancing the barrier properties of films and coated papers.
Implementation Method 1
the polymer mixtures according to the invention have such low water vapor permeability
Data Source
AI summary
The present invention relates to a polymer mixture containing: i) 98 to 99.99 wt.%, based on components i to ii, of a polycondensate obtainable from the monomers: a) at least one α,ω-C18-C30 dicarboxylic acid or a corresponding dicarboxylic acid derivative and b) at least one α,ω-C2-C30 diol, or obtainable from the monomer: a') an ω-hydroxy-α-C10-C26 carboxylic acid; ii) 0.01 to 2 wt.%, based on components i to ii, of at least one natural wax.