Lead Pigment Coating for Weathered Metal Sheet Appearance

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Solution Overview

Problem

Lead aprons and sealing strips made of lead or lead alloys form white lead carbonates when exposed to weather, which are difficult to remove and affect the appearance and longevity of roofing materials, necessitating a solution to maintain the characteristic lead color and luster while preventing corrosion.

Innovation Solution

A metal sheet with a surface coating of colorless paint containing lead pigments or particles, sized between 0.3 μm and 200 μm, is applied to mimic the color and luster of lead, preventing the formation of white lead carbonate and providing weather protection, while being adaptable to existing lead parts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If lead aprons and sealing strips are made of lead or lead alloys, then the characteristic lead color and luster are achieved, but white lead carbonate forms on the surface when exposed to weather, which is difficult to remove and affects appearance

Engineering Contradiction:
Improvelead color and lusterVSAvoidwhite lead carbonate formation
Core Design Contradiction:
Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

A clear paint coating is applied as an intermediary layer between the lead surface and the environment. This coating contains lead particles (0.3-200 μm) that optically mimic the lead surface appearance while the paint matrix prevents actual lead carbonate formation by blocking environmental exposure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The coating is designed to change its optical properties to match lead appearance. By incorporating lead particles of specific size ranges (0.3-200 μm) in a clear paint, the coating reflects and refracts light to produce the characteristic blue-grey lead color and metallic luster without being actual lead metal.

Inventive Principle:
Principle #32Color changes

2Reliability

If a paint coating is applied to lead surfaces, then weather protection is provided and white lead carbonate formation is prevented, but the characteristic lead color and luster are lost

Engineering Contradiction:
Improveweather protectionVSAvoidlead color and luster
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The coating is a composite material combining clear paint (for weather protection) with embedded lead particles (for optical appearance). This composite structure provides both the protective function of paint and the aesthetic function of lead surface, resolving the contradiction between protection and appearance.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The clear paint acts as a protective intermediary that allows the lead particles within it to display their characteristic appearance. The paint matrix protects the lead particles from environmental exposure while the particles themselves provide the optical properties of lead, achieving both protection and appearance simultaneously.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If existing lead parts are to be adapted to match surrounding areas, then color matching is achieved, but the process becomes complex and time-consuming

Engineering Contradiction:
Improvecolor matchingVSAvoidsurface treatment time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The clear paint coating with embedded lead particles naturally produces the characteristic lead color and luster, providing automatic color matching for existing lead parts. This eliminates the need for complex color matching processes, as the coating inherently replicates the appearance of lead regardless of the specific lead alloy composition underneath.

Inventive Principle:
Principle #32Color changes

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 maintains the visual appearance of lead while extending the lifespan of metal sheets, ensuring recyclability and providing effective weather protection, ensuring the metal sheets retain their lead-like appearance and functionality.

Implementation Method 1

the pigments or particles (60) made of lead having a grain size distribution of 0.3 μm to 200 μm with a specific surface area of 1.0 m2/g to 1.5 m2/g. This creates a paint as a coating medium that gives the visual impression of a lead layer.

Methodology Applied
Scientific EffectLight reflection and scattering: Reflection

Data Source

PatentEP2077302B1Sheet metal with a paint coating, which has the colour and brightness of lead
Publication Date: 2016.08.31 ROHR STOLBERG GMBH
  • EP2077302B1 patent drawingFigure 1~4
  • EP2077302B1 patent drawingFigure 5
  • EP2077302B1 patent drawingFigure 6

AI summary

? The metal sheet (10) is made from a flat even formable shaped body (20) such as a plate or foil made from metallic material such as copper, zinc, aluminium, preferably lead. It is in a compound with other metallic materials or in a compound with a plastic sheet or in compound comprising foil and thin plate string or pressed lead base material or a tin-plated lead containing base material. There is a coating (50) with a colour that matches the lead.