Delayed Curing Resin Composition for Pipe Liners
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Solution Overview
Problem
Epoxy resin compositions have limited storage stability and short pot life due to rapid reactivity of nitrogen-containing hardeners, leading to premature curing and handling challenges, especially when applied in wet conditions, which affects adhesion and shelf life.
Innovation Solution
A delayed curing resin composition combining cyclic anhydrides, bisphenol A, and bisphenol F resins with a proprietary activator component that allows for extended shelf life up to six months and delayed curing until elevated temperature, enabling full blending and wetting of liners without immediate curing, even on saturated surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If nitrogen-containing hardeners are used to cure epoxy resins, then curing reactivity and structural properties are improved, but storage stability deteriorates due to premature reaction at room temperature
Solution Approach 1:
The patent divides the curing system into separate components: the epoxy resin containing nitrogen-containing hardener and the epoxide are stored separately and only mixed shortly before processing. This segmentation prevents premature reaction while maintaining the ability to achieve complete curing when needed.
Solution Approach 2:
The patent controls the reactivity by adjusting parameters such as the type of nitrogen-containing base (primary, secondary, or tertiary amines), the epoxide to amine ratio, and the molecular weight of the hardener. These parameter changes allow optimization of both storage stability and curing reactivity.
2Productivity
If high reactivity hardeners are used to achieve fast curing, then productivity is improved, but pot life is reduced making handling difficult
Solution Approach 1:
The patent adjusts the pot life by selecting appropriate nitrogen-containing bases with different reactivity levels, controlling the epoxide to amine ratio, and adjusting the molecular weight of the hardener. These parameter changes enable optimization of both curing speed and working time.
Solution Approach 2:
The patent uses a controlled amount of reactive nitrogen-containing hardener that provides sufficient curing capability when needed but limits premature reaction during storage and handling, achieving a balance between curing speed and pot life.
3Ease of operation
If epoxy resin and hardener are mixed in advance for extended processing, then ease of operation is improved, but storage stability deteriorates due to curing reaction
Solution Approach 1:
The patent maintains the epoxy resin and hardener as separate components during storage and transport, only mixing them shortly before processing. This segmentation allows extended shelf life while enabling complete mixing and processing when needed.
Solution Approach 2:
The patent prepares the epoxy resin with the nitrogen-containing hardener already incorporated in a controlled manner, allowing the mixture to be stored stably for extended periods while maintaining the capability to proceed to complete curing when processed.
4Stability of the object's composition
If adsorption techniques are used to control chemical reactions, then storage stability is improved, but reactivity at curing temperature may deteriorate
Solution Approach 1:
The patent selects nitrogen-containing bases and adjusts parameters such as the epoxide to amine ratio and molecular weight to achieve the desired balance between storage stability and curing reactivity, without requiring adsorption techniques.
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 composition provides a long pot life, allowing for extended storage and transportation of wetted liners without exothermic reactions, ensuring reliable adhesion and curing on wet surfaces, with potential for 100-150 years of service life in pipes, and eliminating the need for refrigerated transport and rushed installations.
Implementation Method 1
the epoxy includes a first base resin matrix formed from a bisphenol material such as bisphenol A (BPA) and at least a second catalyst or hardener... After the two parts are mixed together, they begin a curing process that is typically triggered by exposure to heat, humidity or a ultra-violet light source, whereby the mixed material quickly begins to solidify
Implementation Method 2
a resin composition that allows the resin and catalyst to be mixed for an extended period creating a long pot life composition which cures only when subjected to elevated temperature
Data Source
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AI summary
A resin composition and method for installing a pipe liner that allows the liner to be fully wet out with a resin and activator and stored for a period of up to six months prior to installation and curing. A method of lining a pipe with a delayed curing resin composition is also provided that includes fully wetting out a liner with a blended two part epoxy composition such that the liner can be transported in a wet out fashion, placed in a pipe to be lined and repositioned as needed without concern for the resin composition to begin curing.