Multilayer roofing sheet with mechanical interlock laminate structure

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Solution Overview

Problem

Asphalt-based roofing membranes have low solar reflectivity, leading to high roof temperatures and increased energy consumption, especially in hot climates, as they absorb significant solar radiation, which is a challenge in meeting energy efficiency standards like California's 70% solar reflectance requirement.

Innovation Solution

A multilayer roofing sheet with a textured lower surface and a fusible upper layer, where the upper layer comprises a polymer film with a colorant system like titanium dioxide, and the lower layer includes fibers or non-woven webs, enhancing mechanical interlock and adhesion between layers, and the process involves heating the fusible upper layer to penetrate into the textured lower surface for bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If asphalt-based roofing membranes are used, then waterproofing function is provided, but solar reflectivity is low leading to high roof temperatures

Engineering Contradiction:

Improveroof temperatureVSAvoidenergy consumption for air-conditioning

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The patent creates a composite roofing membrane by bonding an upper sheet (containing polymer film and fibrous or foamed material) to a lower sheet (asphalt-based waterproofing layer). The upper sheet provides high solar reflectivity (exceeding 70% solar reflectance) while the lower sheet provides waterproofing function, thus resolving the contradiction between temperature control and waterproofing.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The roofing membrane is divided into distinct functional layers: an upper sheet with polymer film and fibrous/foamed material for solar reflection and thermal insulation, and a lower sheet for waterproofing. This segmentation allows each layer to optimize its specific function, with the upper layer reflecting solar radiation and the lower layer providing waterproof protection.

Inventive Principle:

Principle #1Segmentation

2Temperature

If multilayer structure is created for improved solar reflectivity, then adhesion between layers becomes challenging

Engineering Contradiction:

Improvesolar reflectivityVSAvoidadhesion between layers

Core Design Contradiction:

TemperatureVSStrength

Solution Approach 1:

The patent applies different surface characteristics to different parts of the sheets: the lower surface of the upper sheet is made textured or porous to facilitate mechanical interlocking, while the upper surface of the lower sheet is made fusible to enable thermal bonding. These localized quality variations ensure strong adhesion between layers while maintaining the desired solar reflectivity properties.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the physical parameters of the sheet surfaces to optimize bonding: the lower surface of the upper sheet is given a textured or porous structure, and the upper surface of the lower sheet is made fusible. These parameter changes enable effective thermal and mechanical bonding between layers, resolving the adhesion challenge in multilayer construction.

Inventive Principle:

Principle #35Parameter changes

3Strength

If textured lower surface is added to upper sheet, then mechanical interlock is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvemechanical interlockVSAvoidmanufacturing process complexity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent employs a porous or textured lower surface on the upper sheet, which can be formed using standard foam fabrication or texturing techniques. This approach provides effective mechanical interlocking with the fusible layer while utilizing established manufacturing methods, thus minimizing the increase in manufacturing complexity.

Inventive Principle:

Principle #31Porous 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 solution provides improved solar reflectivity, mechanical strength, and adhesion between layers, reducing thermal stresses and energy consumption while meeting energy efficiency standards, such as exceeding 70% solar reflectance.

Implementation Method 1

heating the fusible upper layer to penetrate into the textured lower surface for bonding

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

heating the fusible upper layer to penetrate into the textured lower surface

Methodology Applied

Scientific EffectThermal penetration: Conduction (thermal)

Data Source

PatentUS9540820B2Multilayer roofing sheet with mechanical interlock laminate structure

Publication Date: 2017.01.10 CERTAINTEED LLC

AI summary

A multilayer roofing sheet includes a laminate formed from an upper sheet having a textured lower surface and a lower sheet having a fusible upper surface mechanically interlocked together.