Fibre Reinforced Prepreg for Chimney Lining
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Solution Overview
Problem
Current chimney lining materials face issues such as health hazards from harmful components, limited stability, short shelf life, and low thermal resistance, which restrict their applicability and increase application costs, particularly due to water content and sensitivity to temperature.
Innovation Solution
A prepreg composition using a liquid polyisocyanate mixture with more than 50% MDI-based di- and polyisocyanates, combined with powdery inorganic hydroxides, which forms a self-supporting polycarbamide matrix upon heat treatment, offering high thermal resistance and self-extinguishing properties without water and health hazards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chimney lining materials (metal tubes, ceramic tubes, plastic tubes) are used, then corrosion resistance or heat resistance is improved, but installation complexity increases, flexibility decreases, or temperature applicability is limited
Solution Approach 1:
The invention changes the physical state of the lining material from rigid (metal, ceramic, plastic tubes) to flexible prepreg form that can be pulled through the chimney. The material transitions from solid tube form to a flexible band that can be installed without demolition, then cured in place to achieve the desired corrosion and heat resistance properties.
Solution Approach 2:
The invention uses composite materials consisting of inorganic hydroxide particles dispersed in a polyisocyanate binder matrix. This composite structure provides both the flexibility needed for easy installation and the corrosion resistance required for reliable chimney lining, combining properties that were previously mutually exclusive.
2Ease of operation
If existing prepreg materials are used, then installation ease is improved, but thermal resistance decreases and shelf life is limited due to water content and temperature sensitivity
Solution Approach 1:
The invention changes the chemical composition parameters of the prepreg material by using polyisocyanate binders instead of traditional organic resins. This parameter change enables the material to withstand higher temperatures and eliminates water content issues, while maintaining the installation ease benefits of flexible prepreg form.
Solution Approach 2:
The invention creates a prepreg material that does not require refrigeration or short shelf life management. The polyisocyanate-based composition remains stable at room temperature for extended periods, eliminating the need for cold chain logistics and making the material economically viable for widespread use.
3Ease of manufacture
If prepreg materials with water content are used, then processing flexibility is improved, but stability decreases due to sensitivity to temperature and shelf life limitations
Solution Approach 1:
The invention extracts water and other volatile components from the prepreg composition, replacing them with water-free polyisocyanate binders. This extraction eliminates the stability problems associated with water content while preserving the processing flexibility needed for manufacturing and installation.
Solution Approach 2:
The polyisocyanate binder creates an inert, water-free chemical environment within the prepreg structure. This inert atmosphere prevents hydrolysis and other water-related degradation reactions, ensuring long-term compositional stability while maintaining the material's flexibility for easy installation.
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 a prepreg that is storable at room temperature for an indefinite period, exhibits high thermal resistance, and has strong self-extinguishing characteristics, significantly improving shelf life and reducing application costs while maintaining gas and vapor tightness.
Implementation Method 1
a prepreg composition using a liquid polyisocyanate mixture with more than 50% MDI-based di- and polyisocyanates, combined with powdery inorganic hydroxides, which forms a self-supporting polycarbamide matrix upon heat treatment
Implementation Method 2
which forms a self-supporting polycarbamide matrix upon heat treatment
Data Source
Figure 1
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AI summary
SUMMARY The present invention relates to polyisocyanate-based impregnating resin system, which is a liquid polyisocyanate mixture, containing more than 50 % by weight MDI based di- and polyisocyanates, and one or more, originally powdery inorganic hydroxides. The resin system of the invention is suitable for the preparation of prepregs. The invention relates also to the prepreg that can be manufactured with the use of the resin system, and use thereof. Among the uses of the invention one important is the use of the prepreg for lining chimneys.