Polyester Film Composition for Sterilization-Resistant Metal Lamination
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Solution Overview
Problem
Existing thermoplastic resin films used in laminated metal containers suffer from adhesion issues, discoloration during high-temperature sterilization, and limited productivity in manufacturing processes, particularly with non-stretched and longitudinally uniaxially stretched films.
Innovation Solution
A polyester film composed of polyethylene terephthalate and polybutylene terephthalate in specific ratios, manufactured through non-stretched and longitudinally uniaxially stretched processes with controlled stretching and heat-setting, ensuring adhesion and resistance to high-temperature sterilization without significant energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermoplastic resin films are used for laminated metal containers, then adhesion to metal sheets and corrosion resistance are improved, but the films form fine bubbles during high-temperature sterilization causing discoloration and appearance degradation
Solution Approach 1:
The patent changes the chemical composition parameters of the polyester film by incorporating specific ratios of PBT (10-40 mass%) and PC (5-20 mass%) along with PET, and adjusts the intrinsic viscosity parameters to specific ranges. These parameter changes enable the film to maintain adhesion to metal sheets while resisting bubble formation and discoloration during high-temperature sterilization processes.
Solution Approach 2:
The patent creates a composite polyester material by combining multiple polyester types (PET, PBT, PC) with specific compositional ratios. This composite structure leverages the complementary properties of each component: PET provides base adhesion, PBT enhances heat resistance, and PC prevents bubble formation, achieving both reliable adhesion and resistance to sterilization-induced discoloration.
2Productivity
If sequential biaxial stretching is used to produce polyester films, then productivity and thickness accuracy are improved, but equipment cost increases significantly
Solution Approach 1:
The patent modifies the stretching process parameters by specifying precise temperature ranges (50-80°C for longitudinal stretching, 60-90°C for transverse stretching) and stretch ratios (2-6 times longitudinally, 1.5-4 times transversely). These optimized parameters enable effective film production with reduced equipment complexity while maintaining high productivity and thickness accuracy.
3Use of energy by stationary object
If non-stretched polyester films are used, then equipment cost and energy consumption are reduced, but adhesion performance and film uniformity deteriorate
Solution Approach 1:
The patent changes the physical state parameters of the polyester film by implementing controlled stretching processes with specific temperature and stretch ratio parameters. This transforms the film from a non-stretched state with poor adhesion to a stretched state with enhanced molecular orientation and improved adhesion performance, while the optimized parameters keep energy consumption and equipment costs relatively low.
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 polyester film maintains appearance and adhesion after high-temperature sterilization, enabling stable and energy-efficient production of laminated metal sheets and containers.
Implementation Method 1
longitudinally uniaxially stretched
Implementation Method 2
heat-setting
Data Source
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AI summary
Provided are a polyester film and the like that can be stably manufactured with low energy consumption at any stage of the manufacturing process of the film, a laminated metal sheet, and a laminated metal container, and whose film appearance does not deteriorate particularly even after a high-temperature sterilization process. The polyester film contains a first polyester and a second polyester. The first polyester is polyethylene terephthalate or a polyethylene terephthalate copolymer of polyethylene terephthalate and a copolymer component. The second polyester is polybutylene terephthalate or a polyethylene terephthalate copolymer of polybutylene terephthalate and a copolymer component. The ratio of the first polyester to the second polyester is from 20:80 to 50:50 on a mass% basis, and the net intensities in the pole figures satisfy predetermined conditions.