Porous Algae-Resistant Roofing Granules with Controlled Leaching

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Solution Overview

Problem

Existing algae-resistant roofing granules lack control over algaecide leaching rates, making it difficult to tailor roofing products for specific local conditions and providing long-lasting protection against algae growth.

Innovation Solution

The process involves forming algae-resistant roofing granules with mineral particles of smaller average size, aggregated and treated with a binder, and processed using mechanical techniques like extrusion to create porous granules with controlled porosity, allowing for adjustable algaecide leaching rates by incorporating metal oxides such as cuprous oxide and zinc oxide through various methods, including coating and capillary action.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If algaecide is added to color granule coatings to provide long-term protection, then algae resistance duration is improved, but control over leaching rates is lost

Engineering Contradiction:

Improvealgae resistance durationVSAvoidleaching rate control

Core Design Contradiction:

Duration of action of stationary objectVSAdaptability or versatility

Solution Approach 1:

The granules incorporate porous ceramic coatings that control algaecide release through their porous structure. The porosity and composition of the ceramic coating can be engineered to achieve specific leaching rates, enabling both long-term protection and adaptability to different local conditions.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent employs multiple algaecides with different solubility characteristics and releases them at different rates from the granules. By changing the parameters of algaecide selection and ceramic coating composition, the system achieves both extended duration and controllable leaching profiles tailored to specific applications.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If mineral particles are crushed to achieve suitable size, then manufacturing process is simplified, but control over granule porosity is reduced

Engineering Contradiction:

Improvegranule size controlVSAvoidporosity control

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

Instead of crushing mineral particles and then attempting to control porosity, the patent forms granules from smaller mineral particles with binder first, then fires them to create the desired porous ceramic structure. This preliminary formation followed by controlled firing enables both ease of manufacture and precise porosity control.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The granules are formed as composite materials combining mineral particles with organic binder, which is then carbonized during firing to create a porous structure. This composite approach simplifies manufacturing while enabling sophisticated porosity control through the binder composition and firing parameters.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If single algaecide is used in granules, then manufacturing process is simplified, but adaptability to different local conditions is reduced

Engineering Contradiction:

Improvealgaecide incorporationVSAvoidlocal condition tailoring

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent divides the algaecide release function into multiple segments by incorporating different algaecides with distinct release characteristics. Each algaecide segment contributes differently to the overall release profile, enabling tailoring to local conditions while maintaining a unified granule manufacturing process.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The granule system achieves multi-functionality by combining multiple algaecides that release at different rates and under different conditions. This universal design allows a single granule formulation to adapt to various local environmental conditions, replacing the need for multiple specialized formulations.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

This approach enables the production of roofing granules with customizable algaecide release profiles, providing effective algae resistance tailored to specific geographic conditions and extending the protection duration beyond traditional methods.

Implementation Method 1

allowing for adjustable algaecide leaching rates

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

incorporating metal oxides such as cuprous oxide and zinc oxide through various methods, including coating and capillary action

Methodology Applied

Scientific EffectAlgaecidal action of metal oxides:

Data Source

PatentUS7811630B2Algae resistant roofing granules with controlled algaecide leaching rates, algae resistant shingles, and process for producing same

Publication Date: 2010.10.12 CERTAINTEED CORP

AI summary

Algae-resistant roofing granules are formed by extruding a mixture of mineral particles and a binder to form porous granule bodies, and algaecide is distributed in the pores. Release of the algaecide is controlled by the structure of the granules.