Polyester Multilayer Packaging Bag for Microwave Heat and Easy Opening
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Solution Overview
Problem
Existing packaging bags for microwave heating lack sufficient heat resistance, mechanical strength, flexibility, and easy openability, particularly when containing viscous foods with high oil and salt content, and often delaminate during manual opening.
Innovation Solution
A packaging bag formed with a polyester-based multilayer film comprising a biaxially stretched polyethylene terephthalate innermost layer, a polybutylene terephthalate intermediate layer, and optionally a polyethylene terephthalate outermost layer, with heat sealing portions amorphized or low-crystallized by laser light irradiation, and a slit in the intermediate layer to facilitate easy opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an olefin-based resin is used for the heat sealing innermost layer, then the packaging bag has satisfactory heat resistance for normal use, but it lacks sufficient heat resistance for high-power microwave heating or viscous food with large amount of oil and salt content
Solution Approach 1:
The patent changes the material parameter of the heat sealing layer from olefin-based resin to polyester resin, which has higher heat resistance properties. This parameter change enables the packaging bag to withstand high-power microwave heating and viscous food with large amounts of oil and salt content while maintaining satisfactory heat resistance for normal use.
Solution Approach 2:
The patent employs a multilayer film structure combining polyester resin and olefin-based resin in specific configurations. The polyester resin layer provides high heat resistance for the heat sealing function, while the olefin-based resin layer contributes to other protective functions, creating a composite material system that achieves both high heat resistance and comprehensive protection.
2Ease of operation
If a slit is formed in one of the films constituting the multilayer film to allow easy manual opening, then the packaging bag can be opened by hand, but the multilayer film cannot be cut integrally and delamination occurs
Solution Approach 1:
The patent applies local quality by forming a slit only in the olefin-based resin layer while keeping the polyester resin layer intact. This localized modification allows the slit to function as an opening guide without compromising the overall laminate strength, preventing delamination during manual opening while maintaining easy openability.
Solution Approach 2:
The patent segments the film structure by creating a slit in one layer (olefin-based resin) while maintaining the integrity of other layers (polyester resin). This segmentation allows different layers to have different functions: the slit layer provides easy opening guidance, while the intact layers maintain laminate strength and prevent delamination.
3Strength
If the laminate strength of the multilayer film is increased to prevent delamination, then the multilayer film can be cut integrally, but the packaging bag lacks flexibility and may be broken when subjected to drop impact or bent
Solution Approach 1:
The patent uses composite materials with polyester resin and olefin-based resin in a multilayer configuration where each layer contributes different properties. The polyester resin provides high strength and heat resistance, while the olefin-based resin provides flexibility and impact resistance. This composite structure achieves both high laminate strength for integral cutting and sufficient flexibility to withstand drop impact and bending.
Solution Approach 2:
The patent optimizes the thickness parameters and material composition ratios of each layer to achieve the desired balance. By carefully controlling the thickness of the polyester resin layer (providing strength) and the olefin-based resin layer (providing flexibility), the packaging bag achieves both high laminate strength for integral cutting and sufficient flexibility to withstand mechanical stress.
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 excellent heat resistance, mechanical strength, and easy openability, allowing integral tearing without tools, and withstands high-power microwave heating and retort sterilization.
Implementation Method 1
a heat sealing portion that is amorphized or low-crystallized by laser light irradiation
Implementation Method 2
a heat sealing portion that is amorphized or low-crystallized by laser light irradiation
Implementation Method 3
a heat sealing portion that is amorphized or low-crystallized by laser light irradiation
Implementation Method 4
heat sealing properties by laser light irradiation
Data Source
AI summary
A packaging bag including a polyester-based multilayer film. The multilayer film includes at least: an innermost layer formed of a biaxially stretched polyethylene terephthalate film; a layer formed of polybutylene terephthalate; and/or a layer formed of a blend of polyethylene terephthalate and polybutylene terephthalate. The biaxially stretched polyethylene terephthalate film has a heat sealing portion that is amorphized or low-crystallized by laser light irradiation. The packaging bag is formed by allowing the innermost layers of the polyester-based multilayer film to be opposed to and superimposed on each other, and heat sealing the heat sealing portions.