Multilayer Packaging Bag Seals With Oriented Crystals for Drop Strength
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Solution Overview
Problem
Existing packaging bags made from multilayer films with heat-sealable resin layers lack sufficient bag drop strength and recyclability, particularly those using mono-materials like polypropylene, which are prone to breakage when dropped and have poor recyclability due to mixed material configurations.
Innovation Solution
A multilayer film structure is designed with oriented crystals present in the seal portion, comprising a heat-sealable resin layer and a stretched film for reinforcing strength, using olefin resin and a reinforcing resin with a higher melting point, and a substrate film for recyclability, ensuring the presence of oriented crystals during heat sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a multilayer film with different materials (biaxially oriented PET, biaxially oriented nylon, Al, and CPP) is used, then impact resistance is improved, but recyclability deteriorates
Solution Approach 1:
The invention uses a propylene-based resin composition where the base resin, impact copolymer, and LLDPE are all propylene-based materials. This homogeneity in material composition maintains recyclability while the impact copolymer provides the necessary impact resistance, resolving the contradiction between using different materials for strength and material uniformity for recyclability.
Solution Approach 2:
The invention creates a composite resin composition combining base propylene resin, impact copolymer (containing rubber component), and LLDPE. This composite structure provides enhanced impact resistance through the rubber component and LLDPE while maintaining overall propylene-based composition for recyclability, thus resolving the contradiction between strength and ease of manufacture.
2Ease of manufacture
If a polypropylene monomaterial pouch is used, then recyclability is improved, but impact resistance deteriorates
Solution Approach 1:
The invention maintains homogeneity by using only propylene-based materials (base resin, impact copolymer, LLDPE) in the resin composition, ensuring the pouch remains a monomaterial structure suitable for recycling while achieving improved impact resistance through the specific composition and oriented crystal formation.
Solution Approach 2:
The invention changes the physical and chemical parameters of the propylene-based resin composition by incorporating impact copolymer with rubber component and LLDPE, and by controlling crystallization to form oriented crystals. These parameter changes enhance impact resistance while maintaining recyclability through monomaterial composition.
3Ease of operation
If impact polypropylene is blended with linear low-density polyethylene, then heat sealability is improved, but bag drop strength deteriorates
Solution Approach 1:
The invention optimizes the parameters of the resin composition by controlling the types and amounts of base resin, impact copolymer, and LLDPE, and by controlling the crystallization process to form oriented crystals. This resolves the contradiction by achieving both heat sealability and improved bag drop strength through parameter optimization.
Solution Approach 2:
The invention performs preliminary action by forming oriented crystals in the resin composition before film formation and sealing. This pre-formed oriented crystal structure provides enhanced bag drop strength while maintaining the heat sealability of the propylene-based resin composition.
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 packaging bag exhibits significantly improved bag drop strength and maintains recyclability by using a predominantly olefin resin composition, with oriented crystals remaining in the seal portion, enhancing durability and allowing for efficient recycling.
Implementation Method 1
oriented crystals are present in a seal portion formed by bonding the heat-sealable resin layers
Implementation Method 2
oriented crystals are present in a seal portion (that is, a bonded portion of the multilayer films)
Data Source
AI summary
In a packaging bag (10) including multilayer films for packaging (5) including a heat-sealable resin layer (3) on a surface and formed by bonding two of the heat-sealable resin layers (3) of the multilayer films for packaging (5), oriented crystals are present in a seal portion (7) formed by bonding the heat-sealable resin layers (3).