Electronic Ink Roofing Membrane for UV-Stable Color Control

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Solution Overview

Problem

Existing roofing membranes with thermochromic pigments suffer from poor UV-stability, leading to rapid degradation and loss of color-changing ability, making them unsuitable for long-term outdoor use and economically unattractive.

Innovation Solution

A roofing membrane comprising a polymeric waterproofing layer with an electronic ink display that can change color based on user requirements, using electrophoretic, electrowetting, or electrofluidic displays, which are UV-stable and can be easily produced through conventional lamination, printing, or coating techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If thermochromic pigments are used in roofing membranes to enable temperature-dependent color changing, then the membrane can dynamically adjust heat absorption, but the UV-stability deteriorates rapidly leading to degradation and loss of color-changing ability

Engineering Contradiction:
Improvecolor changing abilityVSAvoidUV-stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the fundamental parameter of color adjustment from temperature-dependent (thermochromic) to electrically controllable. By using electrophoretic, electrowetting, or electrofluidic displays, the membrane color can be switched on demand between light-reflecting and dark-absorbing states, eliminating the degradation issue of thermochromic materials while maintaining adaptability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the chemical/physical mechanism of thermochromic pigments with an electrical control system. Electronic ink displays controlled by electrical signals substitute for temperature-responsive molecular changes, providing a more stable and controllable solution for color adjustment in roofing membranes.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Loss of energy

If white or light colored roofing membranes are used to reflect sunlight and reduce heat absorption, then operating costs decrease, but heating costs increase during colder seasons

Engineering Contradiction:
Improveheat absorptionVSAvoidseasonal adaptability
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent makes the roofing membrane dynamically adjustable by incorporating electronic ink displays that can change color on demand. The membrane transitions from a static white or light-colored surface to a dynamic system that can switch between light-reflecting and dark-absorbing states based on seasonal and daily temperature variations, optimizing energy efficiency year-round.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements a control system that monitors temperature conditions and adjusts the membrane color accordingly. Sensors detect environmental temperature, and the control unit activates the electronic ink display to change color - switching to light colors when cooling is needed and dark colors when heating is beneficial, creating a closed-loop feedback system for energy optimization.

Inventive Principle:
Principle #23Feedback

3Loss of energy

If black or dark colored roofing membranes are used to absorb heat energy during colder seasons, then heating costs decrease, but operating costs increase during hot climates

Engineering Contradiction:
Improveheat absorptionVSAvoidexcessive heat absorption
Core Design Contradiction:
Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The patent transforms the static dark-colored membrane into a dynamic system using electronic ink displays. The membrane can switch between dark (heat-absorbing) and light (heat-reflecting) states based on real-time temperature conditions, eliminating the harmful effect of excessive heat absorption during hot climates while maintaining beneficial heat absorption during colder periods.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control system continuously monitors temperature and adjusts the membrane color to prevent harmful heat absorption. When temperatures rise above a threshold, the system activates the electronic ink display to switch to light-reflecting mode, creating a feedback mechanism that prevents excessive heat gain during hot weather while allowing heat absorption when beneficial.

Inventive Principle:
Principle #23Feedback

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 membrane effectively controls heat absorption based on climate conditions, reducing operating costs and greenhouse gas emissions by dynamically adjusting color, while maintaining color-changing properties over several years.

Implementation Method 1

an electrophoretic ink display (3) covering at least a portion of the upper major surface of the waterproofing layer (2)

Methodology Applied
Scientific EffectElectrophoresis: Electrophoresis

Implementation Method 2

The electronic ink display covering at least a portion of the upper major surface of the waterproofing layer is selected from electrophoretic, electrowetting, or electrofluidic displays

Methodology Applied
Scientific EffectElectrowetting: Electrowetting

Implementation Method 3

The electronic ink display covering at least a portion of the upper major surface of the waterproofing layer is selected from electrophoretic, electrowetting, or electrofluidic displays

Methodology Applied
Scientific EffectElectrofluidic effect: Electrohydrodynamics

Implementation Method 4

White or light colored roofing membranes effectively reflect sunlight, which reduces the amount of heat energy absorbed into buildings they cover

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 5

The color of a pre-fabricated or liquid applied roofing membrane has a significant influence on the amount of heat energy absorbed into the membrane from the sunlight

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentEP4479605B1A roofing membrane having a controllable color change
Publication Date: 2025.12.31 SIKA TECH AG
  • EP4479605B1 patent drawingFigure 1~2

AI summary

The invention is directed to a roofing membrane (1) comprising a polymeric waterproofing layer (2) having upper and lower major surfaces and an electronic ink display (3) covering at least a portion of the upper major surface of the waterproofing layer (2). The invention is also directed to a method for producing a roofing membrane and to a method for covering a roof substrate using the roofing membrane of the present invention.