Coated Metal Plate Dent Resistance via Silane and Polyester
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Solution Overview
Problem
Existing coated metal sheets covered with organic resin for producing cans lack sufficient dent resistance, especially when exposed to corrosive contents, and often experience peeling issues during heat treatment, which compromises their applicability and durability.
Innovation Solution
A coated metal sheet with a surface coating film containing a polyester resin having a glass transition temperature of 20 to 55°C, combined with a phenol resin and an acid catalyst, is used, along with an organic resin layer, to enhance adhesion and resistance to heat, shocks, and corrosive substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chromic phosphate treatment is used to improve corrosion resistance and adhesion, then the metal sheet can be excellently applied to producing cans, but the treatment uses harmful chromium compound and the surface treatment film is easily cracked under external shocks
Solution Approach 1:
The patent introduces a silane coupling agent as an intermediary substance between the metal sheet surface and the organic resin coating. This coupling agent forms a transition layer that provides both chemical bonding to the metal surface and compatibility with the organic resin, thereby maintaining adhesion and corrosion resistance without using harmful chromium compounds. The silane coupling agent acts as a mediator that bridges the interface between metal and polymer, solving the environmental harm problem while preserving functional performance.
Solution Approach 2:
The patent changes the chemical composition parameters of the surface treatment by replacing chromium-based compounds with silane-based compounds. This parameter change involves selecting silane coupling agents with specific functional groups that can bond to metal surfaces and organic resins, thereby achieving the same protective function without the harmful effects of chromium. The treatment film composition is modified to include silane compounds instead of chromic phosphate, fundamentally altering the chemical nature of the surface treatment.
2Reliability
If the organic resin layer is applied to provide corrosion resistance, then the can can protect against corrosive contents, but the organic resin layer peels at the flange-forming portion during heat treatment
Solution Approach 1:
The patent applies preliminary surface treatment with silane coupling agent before applying the organic resin coating. This preliminary action creates a prepared surface that enhances the bonding between the metal substrate and the organic resin layer. The silane treatment is performed in advance to ensure proper adhesion foundations are established before the final coating is applied, preventing peeling during subsequent heat treatment processes.
Solution Approach 2:
The patent creates a composite surface treatment system consisting of multiple layers: the metal substrate, the silane coupling agent layer, and the organic resin coating. This composite structure combines the advantages of each material - the metal provides structural strength, the silane coupling agent provides chemical bonding capability, and the organic resin provides corrosion resistance. The composite material system ensures that the organic resin layer remains firmly attached during heat treatment while maintaining corrosion protection.
3Reliability
If the surface treatment film is made hard to improve corrosion resistance, then the metal sheet gains protective properties, but the film is easily cracked when subjected to formation working or external shocks
Solution Approach 1:
The patent employs a thin film approach with silane coupling agent rather than a thick hard coating. This thin film structure provides corrosion resistance while maintaining flexibility and ability to deform with the metal substrate during forming operations and under external shock. The thin silane layer conforms to the metal surface deformations without cracking, unlike harder thicker coatings that would fracture under similar 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 provides seamless cans with excellent dent resistance and applicability, preventing peeling during heat treatment and maintaining integrity even when filled with highly corrosive contents, while also being environmentally friendly and economically advantageous.
Implementation Method 1
forming, on at least one surface of a metal sheet, a coating film that contains a polyester resin having a glass transition temperature (hereinafter often "Tg") of 20 to 55°C, a phenol resin and an acid catalyst
Implementation Method 2
further forming thereon an organic resin layer
Data Source
Figure 1
AI summary
A coated metal sheet further covered with an organic resin obtained by forming, on at least one surface of a metal sheet, a coating film and further forming thereon an organic resin layer. The coating film contains a polyester resin having a glass transition temperature of 20 to 55°C, a phenol resin and an acid catalyst, in order to be able to provide the coated metal sheet further covered with the organic resin that is suited for producing cans and can lids having excellent applicability for producing cans and excellent dent resistance.