Solar-Reflective Roofing Granules with Nanocoatings

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Solution Overview

Problem

Asphalt shingles experience high thermal stresses due to low solar heat reflectance, leading to increased surface temperatures and cooling loads, especially in dark-colored shingles, which affects their service life and aesthetic appeal.

Innovation Solution

Development of solar heat-reflective roofing granules with a base particle coated with a first layer of metal oxide colorant and a second layer of solar heat-reflective nano-pigments or multilayer infrared-reflective films, providing high reflectance in the near-infrared range while maintaining visibility and color.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional pigment-coated mineral rocks are used as roofing granules, then aesthetic appearance is provided, but solar heat reflectance is low and surface temperature increases

Engineering Contradiction:

Improvesurface temperatureVSAvoidmanufacturing process complexity

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The coating is divided into multiple functional layers: a base coating layer providing aesthetic appearance and a top coating layer providing solar heat reflectance. This segmentation allows each layer to be optimized for its specific function while maintaining both requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses composite coating materials comprising multiple pigments and binders in different layers. The base coating contains aesthetic pigments while the top coating contains solar-reflective pigments, creating a composite structure that achieves both appearance and thermal performance.

Inventive Principle:

Principle #40Composite materials

2Duration of action of stationary object

If dark-colored granules are used for aesthetic appeal, then visual attractiveness is improved, but solar heat absorption increases and service life decreases

Engineering Contradiction:

Improveservice lifeVSAvoidsolar heat absorption

Core Design Contradiction:

Duration of action of stationary objectVSIllumination intensity

Solution Approach 1:

The two-layer coating structure separates the aesthetic function (base layer) from the thermal protection function (top layer). This allows dark colors to be used for appearance while the top layer blocks solar heat, extending service life.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the coating structure have different properties: the base coating provides color and aesthetics while the top coating provides thermal reflection. This local differentiation of functions resolves the contradiction between appearance and durability.

Inventive Principle:

Principle #3Local quality

3Temperature

If solar reflective paint with titanium dioxide pigment is applied, then thermal stresses are reduced, but aesthetic appearance becomes undesirable

Engineering Contradiction:

Improvethermal stressVSAvoidaesthetic appearance

Core Design Contradiction:

TemperatureVSIllumination intensity

Solution Approach 1:

The coating is segmented into a base layer for aesthetics and a top layer for thermal reflection. This allows conventional aesthetic pigments to be used in the base layer while solar-reflective pigments are applied in the top layer, achieving both requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent creates a composite coating system where the base coating contains aesthetic pigments and the top coating contains solar-reflective pigments. This composite approach enables both aesthetic appeal and thermal stress reduction simultaneously.

Inventive Principle:

Principle #40Composite materials

4Ease of manufacture

If conventional single-layer coating is used, then manufacturing is simple, but both aesthetic and thermal performance cannot be optimized simultaneously

Engineering Contradiction:

Improvecoating application simplicityVSAvoiddual functionality

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The coating system is segmented into two application steps: base coating for aesthetics and top coating for thermal performance. This segmentation enables dual functionality while maintaining reasonable manufacturing simplicity through standardized coating processes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs composite coating materials with different compositions in each layer. The base coating uses aesthetic pigments while the top coating uses solar-reflective pigments, creating a versatile system that achieves multiple performance targets.

Inventive Principle:

Principle #40Composite materials

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 granules significantly reduce solar heat absorption, lowering surface temperatures and extending the service life of asphalt shingles while maintaining an attractive appearance, thus addressing thermal stress and heat-island effects.

Implementation Method 1

a second layer of solar heat-reflective nano-pigments or multilayer infrared-reflective films... providing high reflectance in the near-infrared range

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

maintaining visibility and color

Methodology Applied

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

Data Source

PatentUS10443241B2Solar heat-reflective roofing granules, solar heat-reflective shingles, and process for producing same

Publication Date: 2019.10.15 CERTAINTEED LLC

AI summary

Solar-reflective roofing granules having improved solar heat-resistance are formed by coating colored mineral particles with a coating composition including titanium dioxide nanoparticles.