Lanthanide Conversion Coating for Hydrogen Sulfide Control in Metal Cans
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Solution Overview
Problem
Metal cans used for packaging liquids that produce hydrogen sulfide suffer from corrosion and tainting due to the production of volatile sulfur compounds, leading to issues like 'rotten egg' odor and spoilage.
Innovation Solution
A metal can with a conversion coating layer comprising lanthanide series elements, Group VIB metals, Group IIIB metals, and phosphorous-containing polymers, combined with a film-forming layer, which reduces oxidation and subsequent hydrogen sulfide production, thereby preventing corrosion and tainting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal cans are used for packaging liquids containing sulfur dioxide or metabisulphite, then the liquid can be stabilized and protected from bacterial and yeast growth, but hydrogen sulfide is produced causing corrosion, rotten egg odor, and tainting of the liquid
Solution Approach 1:
A conversion coating layer comprising lanthanide series elements, Group VIB metals, Group IIIB metals, Group IVB metals, and phosphorous-containing polymers is applied as an intermediary barrier between the metal can substrate and the liquid contents. This coating prevents direct contact between the metal surface and sulfur-containing compounds, thereby eliminating hydrogen sulfide production while maintaining liquid stability
Solution Approach 2:
The conversion coating uses a composite material system combining multiple metal elements (lanthanide series, Group VIB, IIIB, IVB) with phosphorous-containing polymeric materials. This composite structure provides enhanced corrosion resistance and prevents hydrogen sulfide generation while allowing the liquid to maintain its stabilized state
2Reliability
If sulfur dioxide and metabisulphite are added to the liquid, then growth of unwanted bacteria and yeast is prevented, but volatile sulfur compounds are produced causing corrosion and tainting
Solution Approach 1:
The conversion coating acts as a protective intermediary layer that allows the liquid to retain its sulfur dioxide and metabisulphite contents for microbial protection while preventing these compounds from reacting with the metal can to produce harmful volatile sulfur compounds
Solution Approach 2:
The conversion coating creates an inert chemical environment between the metal substrate and the liquid contents, preventing chemical reactions that would otherwise produce hydrogen sulfide and other volatile sulfur compounds, while allowing the liquid's own preservative atmosphere to remain intact
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 maintains hydrogen sulfide concentrations below 35 ppb for at least two months, reducing corrosion and spoilage of contents like wine.
Implementation Method 1
reduces oxidation and subsequent hydrogen sulfide production, thereby preventing corrosion and tainting
Implementation Method 2
The solution effectively maintains hydrogen sulfide concentrations below 35 ppb for at least two months
Data Source
AI summary
This disclosure relates to use of a conversion coating for reduction or prevention of hydrogen sulfide production in cans holding hydrogen sulfide producing liquids, such as wine. This disclosure also relates to metal cans comprising a conversion coating layer deposited on at least a portion of the inside surface of the metal can, a film-forming layer deposited on such conversion coating layer, and a hydrogen sulfide producing liquid deposited inside the metal can.