Multilayer Vessel with N-MXD6 Polyamide for Heat Sterilization
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Solution Overview
Problem
Multilayer vessels made of plastic, particularly those using cycloolefin polymer (COP) and Polymetaxylylene adipamide (N-MXD6), face issues with gas barrier performance and transparency after heat sterilization due to crystallization and blushing, which degrades their performance and appearance.
Innovation Solution
A multilayer vessel design featuring a polyamide resin composition with metaxylylenediamine and straight chain aliphatic α,ω-dicarboxylic acid, combined with calcium hypophosphite, which maintains excellent gas barrier performance and transparency even after heat sterilization by controlling the phosphorus and calcium molar ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If N-MXD6 is used for the gas barrier layer in a multilayer vessel with COP layers, then gas barrier performance is improved, but crystallization occurs during heat forming and sterilization causing blushing and deformation
Solution Approach 1:
The patent modifies the chemical composition parameters of the polyamide resin by controlling the molar ratio of metaxylylenediamine (70-90 mol%) combined with specific dicarboxylic acids (adipic acid 30-60 mol%, isophthalic acid 70-40 mol%). This parameter optimization allows the resin to maintain crystallinity for gas barrier while suppressing excessive crystallization during heat treatment, preventing blushing and deformation.
Solution Approach 2:
The patent creates a composite material system by blending N-MXD6 polyamide resin with specific dicarboxylic acids (adipic acid and isophthalic acid) in controlled ratios. This composite approach combines the high gas barrier properties of N-MXD6 with the thermal stability contributions from the dicarboxylic acid components, achieving both performance and manufacturing reliability.
2Weight of moving object
If plastic vessels are used instead of glass vessels, then weight is reduced and impact resistance is improved, but gas barrier performance deteriorates
Solution Approach 1:
The patent employs a multilayer composite structure where plastic layers (COP for impact resistance and light weight) are combined with a specifically formulated polyamide resin layer (N-MXD6 blended with dicarboxylic acids) that provides superior gas barrier performance. This composite approach allows the vessel to achieve glass-like gas barrier properties while maintaining the inherent advantages of plastic materials.
Solution Approach 2:
The patent applies the gas barrier function locally to the intermediate layer of the multilayer vessel structure. The polyamide resin layer with optimized composition is positioned between the COP layers specifically to provide gas barrier protection, while the outer COP layers maintain impact resistance and light weight properties. Each layer performs its specific function optimally.
3Reliability
If heat sterilization is applied to multilayer vessels with N-MXD6 gas barrier layer, then sterilization is achieved, but blushing occurs degrading transparency
Solution Approach 1:
The patent optimizes the chemical composition parameters of the polyamide resin by incorporating specific dicarboxylic acids (adipic acid 30-60 mol%, isophthalic acid 70-40 mol%) combined with metaxylylenediamine. This compositional parameter control modifies the crystallization behavior during heat sterilization, allowing the material to withstand sterilization temperatures without excessive crystallization that causes blushing, thereby maintaining transparency while achieving sterilization.
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 ensures the multilayer vessel retains high gas barrier performance and transparency, similar to glass vessels, while preventing blushing and deformation, making it suitable for medical packaging that requires heat sterilization.
Implementation Method 1
N-MXD6, however, very quickly crystallizes at 250 to 320° C., which is a temperature range for heat forming of the polyolefin resin such as COP.
Implementation Method 2
Other known methods include a method of adding a nucleation agent for crystallization to N-MXD6; and a method of blending a crystalline polyamide resin such as nylon 6, which acts as a nucleation agent for crystallization in the process of heat sterilization, with N-MXD6.
Data Source
AI summary
Provided is a multilayer vessel excellent in gas barrier performance and transparency and its application. The multilayer vessel contains a layer (X) that contains at least one type of polyolefin resin as the major ingredient; and a layer (Y) that contains a polyamide resin (A) as the major ingredient, the polyamide resin (A) being composed of a structural unit derived from diamine, and a structural unit derived from dicarboxylic acid, 70 mol % or more of the structural unit derived from diamine being derived from metaxylylenediamine, meanwhile 30 to 60 mol % of the structural unit derived from dicarboxylic acid being derived from straight chain aliphatic α,ω-dicarboxylic acid having 4 to 20 carbon atoms, and 70 to 40 mol % being derived from isophthalic acid.