Drawn-Ironed Can Coating for High-Speed Forming Without Peeling
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Solution Overview
Problem
Existing methods for producing drawn/ironed cans using coated metal sheets with high glass transition temperature polyester resin coatings face issues such as coating film defects during processing and peeling during heat treatment, leading to reduced flavor sorption resistance and increased metal exposure.
Innovation Solution
A method involving high-speed drawing and ironing at 2000 mm/sec with a coated metal sheet having an inner surface coating film made of a polyester resin with a glass transition temperature of 55°C or higher, containing a curing agent, and optionally an outer surface coating film, to prevent coating film defects and peeling, ensuring excellent flavor sorption resistance and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyester resin with high glass transition temperature is used to form the inner surface coating film, then flavor sorption resistance is improved, but coating film defects and peeling occur during processing
Solution Approach 1:
The patent applies parameter changes by controlling the glass transition temperature of the polyester resin within a specific range (55-120°C) and adjusting the ironing rate (40-80%) and processing speed (2000-5000 mm/sec) to optimize both flavor sorption resistance and coating film coverage, preventing defects and peeling during processing
Solution Approach 2:
The patent employs dynamics by using high-speed processing (2000-5000 mm/sec) to dynamically control the coating film behavior during drawing and ironing, allowing the coating to properly adhere and cover the can inner surface while maintaining the desired flavor sorption resistance properties
2Manufacturing precision
If high-speed drawing and ironing is performed, then coating film defects are prevented, but processing speed must be precisely controlled
Solution Approach 1:
The patent specifies precise parameter ranges including processing speed (2000-5000 mm/sec), ironing rate (40-80%), and glass transition temperature (55-120°C) to achieve optimal coating film coverage while preventing defects, balancing manufacturing precision with controlled processing complexity
3Stability of the object's composition
If the coating film is subjected to heat treatment, then residual stress is reduced, but coating film peeling may occur
Solution Approach 1:
The patent controls the glass transition temperature of the polyester resin within 55-120°C and adjusts the ironing rate and processing speed to manage residual stress in the coating film, preventing peeling during heat treatment while maintaining coating film coverage and integrity
Solution Approach 2:
The patent uses dynamic processing at high speeds (2000-5000 mm/sec) to control the coating film's response to heat treatment, allowing residual stress to be managed without causing peeling, thus maintaining both stability and manufacturing precision
4Reliability
If a thick coating film is formed, then flavor sorption resistance is improved, but film thickness control becomes difficult and economic efficiency decreases
Solution Approach 1:
The patent optimizes the glass transition temperature of the polyester resin (55-120°C) and controls processing parameters (ironing rate 40-80%, speed 2000-5000 mm/sec) to achieve adequate flavor sorption resistance with controlled film thickness, improving ease of manufacture and economic efficiency
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 method produces drawn/ironed cans with improved coating film coverage and corrosion resistance, preventing metal exposure and maintaining flavor sorption resistance, even after heat treatment, by using high-speed processing to soften the coating film and reduce residual stress.
Implementation Method 1
a glass transition temperature of 55°C or higher
Implementation Method 2
high-speed drawing and ironing at 2000 mm/sec... by using high-speed processing to soften the coating film and reduce residual stress
Data Source
AI summary
The disclosure relates to a method for producing a drawn/ironed can, including drawing and ironing a coated metal sheet, the coated metal sheet having an inner surface coating film at least on a surface to be a can inner surface. A glass transition temperature (Tg) of a polyester resin contained in the inner surface coating film is 55° C. or higher, an ironing rate in the drawing and ironing is 40% or greater, and a processing speed during ironing in the drawing and ironing is 2000 mm/sec or higher. Thus, even in a case where a coated metal sheet having a coating film with excellent flavor sorption resistance and contains a polyester resin having a high glass transition temperature as a main component is used, occurrence of a coating film defect during molding and occurrence of coating film peeling due to heat treatment can be suppressed.