Polyester Resin-Coated Metal Sheet for Seamless Cans
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Solution Overview
Problem
Polyester resin-coated seamless cans experience ink exfoliation due to severe processing and residual stress issues, which affect decorative and photoluminescence properties during forming and heat treatment.
Innovation Solution
A polyester resin-coated metal sheet with non-oriented layers having a difference in melting temperature and tensile stress, and containing fine particles, which reduces residual stress and enhances adhesion and formability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If severe processing methods such as thin-wall drawing are used to reduce weight and material cost, then productivity and cost efficiency are improved, but the coating film is liable to undergo damaging such as film cracking and exfoliation
Solution Approach 1:
The coating film is divided into multiple layers with different properties: a base layer for adhesion and a surface layer for flexibility and damage resistance. This segmentation allows each layer to perform its specific function, preventing film cracking and exfoliation during severe processing while maintaining productivity
Solution Approach 2:
The patent uses a composite coating structure combining polyester resin with inorganic fine particles (such as silica) to create a material that exhibits both adhesion and flexibility. The composite nature allows the coating to withstand severe forming operations like thin-wall drawing without cracking or exfoliating
2Illumination intensity
If various decorations and printing techniques are applied to enhance design properties, then decorative property is improved, but ink exfoliation is liable to occur due to neck processing and mutual contact
Solution Approach 1:
The coating film is designed with predetermined flexibility and adhesion properties before printing and decoration processes. The multi-layer structure with controlled tensile stress differences ensures that the coating can accommodate subsequent neck processing and handling without causing ink exfoliation, even when decorative elements are applied
Solution Approach 2:
The patent controls specific parameters of the coating film including tensile stress at elongation, melting temperature differences between layers, and fine particle content. These parameter optimizations ensure the coating maintains both decorative quality and ink adhesion resistance during subsequent processing and handling
3Reliability
If the tensile stress difference between layers is reduced to prevent film damage, then coating film integrity is improved, but the ability to withstand severe forming processing may be compromised
Solution Approach 1:
Different layers of the coating film are designed with locally optimized properties: the base layer has higher adhesion strength for metal substrate bonding, while the surface layer has controlled tensile stress characteristics for flexibility. This local quality differentiation allows the coating to both withstand severe forming and maintain integrity without requiring uniform stress distribution throughout
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 ink exfoliation during severe processing, maintaining high decorative and photoluminescence properties while withstanding severe forming and heat treatment processes.
Implementation Method 1
a surface layer and an adjacent layer in contact with the surface layer have a difference therebetween in melting temperature of not less than 10° C.
Implementation Method 2
a difference therebetween in tensile stress at an elongation of 250% under an environmental temperature of 70° C. of less than 3 MPa
Implementation Method 3
it is possible to provide a polyester resin-coated metal sheet which shows excellent coating material adhesion capable of withstanding severe forming processing
Data Source
AI summary
[Problem] To provide a polyester resin-coated metal sheet which has excellent coating material adhesion capable of withstanding severe forming processing while retaining high decorative property and photoluminescence property and a container using the same. [Solution] The polyester resin-coated metal sheet of the present invention includes a metal sheet, and a non-oriented polyester resin formed of a plurality of layers provided on at least one surface of the metal sheet. A surface layer and an adjacent layer in contact with the surface layer, of the plurality of layers, have a difference therebetween in melting temperature of not less than 10° C., and a difference in tensile stress at an elongation of 250% under an environmental temperature of 70° C. of less than 3 MPa in tensile tests in a single-layer film state corresponding to each layer, and the surface layer contains fine particles.