Self-Adhesive Bitumen Web with Partial Bonding for Stress Relief
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Solution Overview
Problem
Existing self-adhesive bitumen sheets with full-surface bonding face challenges in vapor pressure equalization and thermal stress compensation, and require post-processing for seamless connection of adjacent sheets, leading to potential issues with tightness and adhesion.
Innovation Solution
A self-adhesive bitumen sheet with partial bonding on the underside, featuring non-adhesive strips parallel to the broad side and separated from the long sides, creating an adhesive ladder pattern, allowing for continuous connection without additional measures, and using a separating film to prevent self-adhesion during rolling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If full-surface bonding is used, then adhesion strength is improved, but vapor pressure equalization deteriorates and thermal stress compensation becomes impossible
Solution Approach 1:
The bonding surface is segmented into adhesive strips and non-adhesive strips alternating in the longitudinal direction. This segmentation allows vapor pressure to equalize through the non-adhesive regions while maintaining strong adhesion through the adhesive strips, thus resolving the contradiction between adhesion strength and vapor pressure equalization.
Solution Approach 2:
Different regions of the self-adhesive web are assigned different bonding properties: adhesive strips provide strong bonding to the substrate, while non-adhesive strips provide vapor permeability and thermal stress relief. This local differentiation of properties allows the system to simultaneously achieve strong adhesion and vapor pressure equalization.
2Ease of manufacture
If non-adhesive material is applied to prevent sticking, then self-adhesion during rolling is prevented, but post-processing is required to remove the material for seamless connection
Solution Approach 1:
The web is segmented into adhesive and non-adhesive strips, where the non-adhesive strips serve dual purposes: preventing self-adhesion during rolling and storage, and providing vapor permeability. This eliminates the need for additional release materials and their subsequent removal, reducing post-processing complexity.
Solution Approach 2:
The non-adhesive strips perform multiple functions simultaneously: they prevent self-adhesion during rolling, allow vapor pressure equalization, and provide thermal stress compensation. This multi-functionality eliminates the need for separate release materials and their removal processes.
3Reliability
If non-adhesive and non-melting material is used for coverage, then vapor pressure equalization is achieved, but connection between sheets requires post-processing
Solution Approach 1:
The web is divided into alternating adhesive and non-adhesive strips. The non-adhesive strips enable vapor pressure equalization, while the adhesive strips at the edges provide continuous bonding capability for seamless connection between sheets without requiring post-processing removal of release materials.
Solution Approach 2:
Different regions serve different functions: non-adhesive strips in the center provide vapor permeability, while adhesive strips at the edges provide bonding capability for continuous connection. This local differentiation allows both vapor pressure equalization and easy connection between sheets.
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
Enables effective compensation of thermal stresses and expansion, allows for seamless connection of sheets on both long and broad sides without post-processing, ensuring tightness and ease of installation while maintaining vapor pressure equalization.
Implementation Method 1
It has been found that this makes it impossible to equalize the vapor pressure
Implementation Method 2
Self-adhesive sheets have long been used in construction. They consist of bitumen, which is reinforced by an insert
Implementation Method 3
To prevent the rolled-up sheet from sticking in the self-adhesive areas, a separating film or laminated film must be applied to the underside over the whole or part of the surface
Data Source
Figure 1
Figure 2
AI summary
The bitumen self-adhesive strip (1) has strips (2) on the underside to achieve partial bonding, which are provided with a non-adhesive layer, which are attached parallel to the broad side of the self-adhesive strip and end at a distance from the long sides, the strips (2) are completely separate from each other. As a result, thermal stresses can be compensated for and adjacent webs can still be securely and easily connected to one another both on the long sides and on the short sides. The non-adhesive layer of the strips (2) can be formed by scattered sand. Preferably, the upper side is non-adhesive, e.g. sprinkled, with the exception of two edge strips (9, 10) parallel to the long sides, and the lower side has a non-adhesive strip (3) along one long side and an adhesive strip (4) on the other long side.