Copolyester Sealing Layer for Blister Package Bonding
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Solution Overview
Problem
Blister packages with laminate structures face challenges in bonding with strain-hardened aluminum foil, particularly when using thermoplastic materials like uncoated PET or biaxially oriented Nylon, leading to poor bonding performance and increased manufacturing complexity and cost with additional coating layers.
Innovation Solution
A multilayer film with a first formable layer of a thermoplastic material and a sealing layer of a copolyester material, where the sealing layer has crystallinity between 5% to 20% as measured by differential scanning calorimetry, allowing direct heat-sealing to a lacquer layer on strain-hardened aluminum foil without additional coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an additional coating layer (e.g., Vinoyl 15/45M) is added to improve bonding performance, then bonding strength is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the additional coating layer from the laminate structure. By formulating the copolyester sealing layer with specific composition (5-20% crystallinity) and properties, the bonding function previously requiring a separate coating layer is integrated directly into the sealing layer itself, thereby removing the need for Vinoyl 15/45M or similar coating layers while maintaining bonding strength
Solution Approach 2:
The patent merges the sealing function and bonding function into a single copolyester sealing layer. This layer combines the heat-sealing properties needed for forming the blister package with the bonding properties needed to adhere to the lacquer layer on aluminum foil, eliminating the need for separate coating layers and simplifying the manufacturing process
2Ease of manufacture
If thermoplastic materials like uncoated PET or biaxially oriented Nylon are used, then manufacturing cost is reduced, but bonding performance deteriorates
Solution Approach 1:
The patent changes the key parameter of crystallinity to a specific range (5-20%) in the copolyester sealing layer. This parameter optimization enables the material to achieve both cost-effectiveness (using common thermoplastic materials) and superior bonding performance (through controlled crystallinity that enhances adhesion to lacquer layers), resolving the contradiction between low cost and high bonding performance
Solution Approach 2:
The patent uses copolyester as a composite material that combines the advantages of different polymers. The copolyester structure provides both the heat-sealing capabilities of thermoplastics and enhanced bonding properties, allowing direct adhesion to lacquer layers without requiring additional coating layers or expensive specialized materials
3Strength
If additional coating layers are applied to formable films, then bonding performance is improved, but manufacturing time and process complexity increase
Solution Approach 1:
The patent removes the additional coating layer application step from the manufacturing process. By incorporating bonding capabilities directly into the copolyester sealing layer through compositional design (5-20% crystallinity), the separate coating application process is eliminated, reducing manufacturing time and process complexity while maintaining bonding performance
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
This solution enhances the bonding strength and reduces manufacturing complexity and cost by eliminating the need for additional coatings, while maintaining the integrity of the blister package construction.
Implementation Method 1
a sealing layer of a copolyester material... which is heat-sealable to a lacquer layer on strain-hardened aluminum foil
Data Source
AI summary
Embodiments of the disclosure relate to a blister package having a laminate structure that is heat-sealable to a lacquer layer on strain-hardened aluminum foil. The blister package includes a lid layer comprising a strain-hardened aluminum foil, a lacquer layer on a sealing surface of the strain-hardened aluminum foil and a laminate structure sealed directly to the lacquer layer. The laminate structure includes a multilayer film and a plurality of wells formed therethrough. The multilayer film includes a first formable layer of a thermoplastic material and a sealing layer of a copolyester material. The sealing layer overlies the first formable layer and has an outer surface opposite the first formable layer. The sealing layer has crystallinity from 5% to 20% as measured by differential scanning calorimetry (DSC). The outer surface of the sealing layer is sealed directly against the lacquer layer.