Copper Tin Red Pigment for Cadmium-Free Glass Coloration
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Solution Overview
Problem
The challenge in achieving a deep, vivid red color in glass and enamel compositions without using cadmium, lead, or chromium, as traditional red pigments often result in brownish tones and contain heavy metals that are environmentally hazardous.
Innovation Solution
Development of low-firing, high-durability glass and enamel compositions that utilize a red copper ruby glass pigment, formed by a redox reaction between copper and tin ions, which are applied to substrates through various printing methods and fired to achieve a cadmium-free, lead-free red color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional red pigments (iron oxide, lead oxide, cadmium sulfide) are used to impart red color to glass and enamel, then a red color can be achieved, but the color becomes brownish and environmentally hazardous heavy metals are introduced
Solution Approach 1:
The patent changes the chemical parameters by using copper oxide (CuO) and tin oxide (SnO2) as the colorant system instead of traditional iron oxide, lead oxide, or cadmium sulfide. This parameter substitution achieves deep vivid red color while eliminating harmful heavy metals from the composition.
Solution Approach 2:
The patent converts the potentially harmful effect of copper (which can give green or blue colors) into a beneficial deep red color by controlling the redox reaction conditions and using tin oxide as a reducing agent. The copper ions are reduced to metallic copper particles that provide the desired red coloration.
2Illumination intensity
If iron oxide is used to impart red color, then a red tone is achieved, but unwanted side effects occur
Solution Approach 1:
The patent extracts and removes iron oxide from the colorant system entirely, replacing it with a copper-tin based system. This eliminates the unwanted side effects associated with iron oxide while maintaining the red coloration through the formation of metallic copper particles.
3Illumination intensity
If cadmium-containing pigments are used to achieve red color, then a vivid red can be obtained, but environmental scrutiny increases due to heavy metal content
Solution Approach 1:
The patent uses readily available copper oxide and tin oxide as inexpensive, non-hazardous alternatives to expensive and hazardous cadmium-based pigments. The copper-tin system provides comparable or superior red coloration without the environmental hazards of cadmium.
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 allows for the production of a true red color on glass, metal, and ceramic substrates using a cadmium-free formulation, with the ability to apply the pigment through screen printing, spraying, or thermoplastic printing, and can be used to directly color plastics, ensuring a stable and environmentally friendly red coloration.
Implementation Method 1
Partles or clusters of metallic copper are formed in a redox reaction between copper ions and tin ions
Data Source
AI summary
This invention relates to lead free and cadmium free copper-containing glass frits that can be used as pigments to color other glass frits or to impart color to solid substrates such as glass, ceramic or metals, or to impart color to a thermoplastic mass. The compositions comprise silica, alkali metal oxides, alkaline earth metal oxides, tin oxide and copper oxide. The resulting compositions can be used to decorate and protect automotive, beverage, architectural, pharmaceutical and other glass substrates, generally imparting a red color.