Microwave-Resistant Paper Container Sealant
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Solution Overview
Problem
Existing paper containers are not suitable for heating in microwave ovens due to issues with waterproofing, as the polyethylene layer can foam and create pinholes, leading to contamination, and using high-melting-point resins reduces production efficiency.
Innovation Solution
A paper container with a sealant layer made of homopolymer-type polypropylene having a melting point of at least 135°C and a thickness of 20 µm or more, combined with an anchor layer of acid-modified polypropylene resin aqueous dispersion, which enhances adhesion and prevents peeling during microwave heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyethylene layer is provided on the inner surface to improve waterproof characteristic, then waterproofing is improved, but the layer may foam and form pinholes when heated by microwave oven, causing contamination
Solution Approach 1:
The patent changes the material parameter from polyethylene to polypropylene resin, which has a higher melting point and does not foam when exposed to microwave heating. This parameter change resolves the contradiction by maintaining waterproofing while eliminating pinhole formation under microwave heating conditions.
Solution Approach 2:
The patent uses a composite structure consisting of a paper blank and a polypropylene resin layer laminated thereon. This composite material approach combines the waterproofing capability of polypropylene with the microwave heating resistance, solving both the waterproofing requirement and the microwave compatibility issue simultaneously.
2Object-affected harmful factors
If an inner layer is formed using a resin having a high melting point to prevent foaming, then pinhole formation is prevented, but the production efficiency of the paper container is significantly reduced
Solution Approach 1:
The patent optimizes the melting point parameter of the polypropylene resin to be within a specific range (130-160°C) that balances microwave heating resistance with manufacturability. This parameter optimization allows the resin to resist foaming during microwave use while still enabling efficient production through standard heating processes.
3Reliability
If a polyethylene layer is used for waterproofing, then water resistance is improved, but the layer is not suitable for microwave heating, creating a contradiction in usability
Solution Approach 1:
The patent changes the material composition parameter from polyethylene to polypropylene resin, which fundamentally alters the thermal behavior to be compatible with microwave heating while maintaining water resistance. This material substitution resolves the adaptability contradiction.
Solution Approach 2:
The patent employs a composite material system where polypropylene resin serves dual functions: providing waterproofing like polyethylene but with added microwave heating compatibility. This composite approach enables the container to adapt to both waterproofing requirements and microwave heating conditions.
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 effectively prevents pinhole formation and ensures reliable sealing, maintaining adhesion and production efficiency, even when heated in a microwave oven, while allowing for easy disposal as combustible waste.
Implementation Method 1
a sealant layer made of homopolymer-type polypropylene having a melting point of at least 135°C
Implementation Method 2
when the layer is heated by a microwave oven, the polyethylene layer may foam to form pinholes
Implementation Method 3
an anchor layer of acid-modified polypropylene resin aqueous dispersion, which enhances adhesion and prevents peeling during microwave heating
Implementation Method 4
homopolymer-type polypropylene having a melting point of at least 135°C
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
In a paper container including a container main body formed by folding a blank formed of a sheet-shaped material, the sheet-shaped material includes a base material of paper, an anchor layer formed on the base material, and a sealant layer having a thickness of 20 µm or more and less than 60 µm formed on the anchor layer. The anchor layer is formed of acid-modified polypropylene resin aqueous dispersion and a melting point of polypropylene contained in the acid-modified polypropylene resin aqueous dispersion is 120 °C or more. The sealant layer is formed of homopolymer type polypropylene and the melting point of the homopolymer type polypropylene is 135 °C or more.