Polyamide-EVOH Laminate for Stand-Up Pouch Fall Resistance
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Solution Overview
Problem
Existing stand-up pouches with EVOH barrier layers suffer from low bag falling resistance after retort treatment, leading to potential leakage during transportation and display.
Innovation Solution
A laminate structure with specific elastic modulus ratios in orthogonal directions, including a polyamide-based resin layer and EVOH layer, and a heat sealing layer with a thermoplastic elastomer, ensuring a product of tensile elastic moduli in different directions is 0.22 (GPa)^3 or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stand-up pouch uses an Al foil barrier layer, then oxygen barrier property is improved, but microwave oven usability deteriorates
Solution Approach 1:
The patent removes the Al foil barrier layer from the laminate structure and replaces it with a polyamide-based resin layer containing EVOH. This extraction of the microwave-incompatible material resolves the contradiction by eliminating the barrier to microwave heating while maintaining oxygen barrier functionality through the alternative material composition.
Solution Approach 2:
The patent changes the material composition parameters of the barrier layer by using polyamide-based resin with EVOH instead of Al foil. This parameter change enables microwave compatibility while preserving the essential oxygen barrier function, thus resolving the contradiction between barrier performance and microwave usability.
2Strength
If the elastic modulus of the laminate is increased to improve stiffness, then self-supporting property is improved, but bag falling resistance deteriorates
Solution Approach 1:
The patent optimizes the elastic modulus parameters of the laminate by controlling the ratio between the elastic modulus in the reference direction (A) and the 45-degree direction (B). By setting A/B within 0.1 to 10, the laminate achieves balanced mechanical properties that simultaneously provide self-supporting capability and impact resistance, resolving the contradiction between stiffness and falling resistance.
Solution Approach 2:
The patent employs a composite laminate structure combining polyamide-based resin, EVOH layer, and heat sealing layer with specific elastic modulus characteristics. This composite construction allows the material to exhibit both high self-supporting property and excellent bag falling resistance by leveraging the complementary properties of different material layers.
3Reliability
If thermoplastic elastomer concentration in heat sealing layer is increased to improve bag falling resistance, then impact resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent simplifies the manufacturing process by specifying a clear concentration range for thermoplastic elastomer in the heat sealing layer (0.1 to 60 parts by mass per 100 parts of polypropylene). This parameter specification provides straightforward manufacturing guidance while achieving the desired bag falling resistance, avoiding excessive manufacturing complexity.
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 laminate provides excellent bag falling resistance and maintains low oxygen permeability after retort treatment, ensuring the pouch's integrity during handling and storage.
Implementation Method 1
a concentration of the thermoplastic elastomer on the heat sealing resin (D) layer is lower on a surface layer at an opposite side of the protection layer (A) side than on a surface layer at the protection layer (A) side
Implementation Method 2
the elastic modulus of the laminate is too high, so that the stand-up pouch disclosed in Patent Literature 2 has low bag falling resistance after the retort treatment
Implementation Method 3
the barrier layer has a polyamide-based resin layer and an ethylene-vinyl alcohol-based copolymer layer... low oxygen permeability after retort treatment
Data Source
AI summary
The present invention relates to a laminate including a protection layer, a barrier layer, and a heat sealing layer, in which a product of a tensile elastic modulus A in a reference direction, a tensile elastic modulus B in a direction forming an angle of 45° with respect to the reference direction, and a tensile elastic modulus C in a direction forming an angle of 90° with respect to the reference direction is 0.22 (GPa)3 or less, and a value of the tensile elastic modulus B to the tensile elastic modulus A, a value of the tensile elastic modulus C to the tensile elastic modulus A, and a value of the tensile elastic modulus C to the tensile elastic modulus B are each 0.1 to 10.