Gas-Barrier Packaging Material with Protective Layer
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Solution Overview
Problem
Conventional gas-barrier packaging materials face issues with degradation under humid conditions, poor resistance to abuse such as bending and extension, and require retort processing, which can lead to cracked films and poor water vapor barrier properties.
Innovation Solution
A gas-barrier packaging material comprising a support, adhesive layer, first barrier layer, second barrier layer, and a protective layer formed from a coating liquid containing a polyvalent metal compound, polyester-based resin, and sodium salt of a polycarboxylic acid-based resin, with specific infrared absorption spectrum ratios to enhance oxygen and water vapor barrier properties without retort processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polycarboxylic acid based polymer layer and a polyvalent metal compound containing layer are adjacently deposited to form a polyvalent metal salt by intercalation reaction, then gas-barrier properties against oxygen under high humidity are improved, but retort processing or intercalation reaction is required which degrades water vapor barrier properties and causes film cracking
Solution Approach 1:
The patent changes the chemical composition parameters of the protective layer by incorporating specific components (polyester-based resin, polyvalent metal compound, and dispersant) in controlled ratios. This composition adjustment enables the layer to provide gas-barrier properties without requiring retort processing or intercalation reactions, thus maintaining water vapor barrier properties and preventing film cracking while achieving oxygen barrier performance under high humidity conditions.
2Reliability
If a deposited film formed of an inorganic compound is used to provide oxygen and water vapor barrier properties, then barrier properties are improved, but the film is easily cracked when subjected to bending, extension, or high temperature and high pressure processing
Solution Approach 1:
The patent creates a composite protective layer combining polyester-based resin with polyvalent metal compound and dispersant. This composite structure provides both the barrier properties of inorganic compounds and the flexibility and crack resistance of organic polymers, enabling the film to withstand bending, extension, and high temperature processing while maintaining oxygen and water vapor barrier performance.
Solution Approach 2:
The dispersant acts as an intermediary component that facilitates uniform distribution of the polyvalent metal compound within the polyester-based resin matrix. This intermediary role ensures the protective layer maintains structural integrity and flexibility, preventing cracking during abuse or processing while preserving the barrier properties provided by the metal compound.
3Ease of operation
If liquid precursors for coating liquids are stored without addition of hardener, then storage is simplified, but the precursors easily form aggregates because of poor stability
Solution Approach 1:
The dispersant serves as a stabilizing intermediary in the liquid precursor coating liquid, preventing aggregation of the polyvalent metal compound and polyester-based resin components during storage. This allows the coating liquid to be stored without adding hardener while maintaining compositional stability, and the hardener can be added immediately before use to complete the formulation.
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 provides improved oxygen and water vapor barrier properties, abuse resistance, and stability under high temperature and pressure conditions, while eliminating the need for retort processing and extending the storage life of the coating liquid.
Implementation Method 1
a protective layer which is formed of a coating liquid containing a polyvalent metal compound, a polyester based resin, and a dispersant that is a sodium salt of a polycarboxylic acid based resin
Implementation Method 2
improved oxygen and water vapor barrier properties
Implementation Method 3
when the second barrier layer is separated and an infrared absorption spectrum of the second barrier layer after separation is measured by a transmission method
Data Source
AI summary
A gas-barrier packaging material including: a support; an adhesive layer laminated on the support; a first barrier layer laminated on the adhesive layer; a second barrier layer laminated on the first barrier layer; and a protective layer formed of a coating liquid that contains a polyvalent metal compound, a polyester based resin, and a dispersant that is a sodium salt of a polycarboxylic acid based resin, the protective layer being laminated on the second barrier layer. In the gas-barrier packaging material, the protective layer contains the polyvalent metal compound by about 40 to 90 wt % relative to 100 wt % of the protective layer. When the second barrier layer is separated and an infrared absorption spectrum of the second barrier layer after separation is measured by a transmission method, a ratio between a maximum peak height α in a range of about 1,490 to about 1,659 cm−1 and a maximum peak height β in a range of about 1,660 to about 1,750 cm−1 as expressed by α/β is less than about one.