Cold-Shrink Article Using Fluoroelastomer and Epichlorohydrin
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Solution Overview
Problem
Conventional cold-shrink articles lack stability at elevated temperatures and resistance to acidic, caustic substances, and hydrocarbon fluids, which limits their effectiveness in harsh environments.
Innovation Solution
The development of elastomeric compositions incorporating a fluoroelastomer and epichlorohydrin, along with optional additives like pigments and energy-beam absorbents, which form cold-shrink articles that maintain integrity and resistance to tearing at elevated temperatures and in chemically challenging conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional elastomeric compositions (EPDM rubber or silicone rubber) are used to form cold-shrink articles, then the articles can be expanded and contracted without breakage at low temperatures, but the articles lack stability at elevated temperatures and resistance to acidic, caustic substances, and hydrocarbon fluids
Solution Approach 1:
The patent uses a composite elastomeric composition comprising fluoroelastomer (20-80 parts by weight), epichlorohydrin polymer (20-80 parts by weight), and optional additives including plasticizers, fillers, and crosslinking agents. This composite material combines the heat resistance of fluoroelastomer with the chemical stability of epichlorohydrin polymer, achieving both high-temperature stability (maintaining integrity at 150°C for extended periods) and resistance to acidic, caustic, and hydrocarbon environments while retaining elastic properties for expansion and contraction
2Strength
If the cold-shrink article is designed to shrink fully to a relaxed state, then the article achieves maximum engagement with the substrate, but the article may tear or crack at elevated temperatures during expansion and contraction
Solution Approach 1:
The patent modifies the material parameters by selecting specific fluoroelastomer types (e.g., Viton® A, B, G, or copolymers of vinylidene fluoride with tetrafluoroethylene and hexafluoropropylene) and epichlorohydrin polymer grades, along with optimizing the compositional ratios and adding plasticizers (1-20 parts by weight) to enhance flexibility. This enables the article to maintain tear resistance at 150°C while preserving the ability to expand 200-300% and contract without cracking
Solution Approach 2:
The patent incorporates crosslinking agents (1-10 parts by weight per 100 parts elastomer) and antioxidants (1-5 parts by weight per 100 parts elastomer) in advance to pre-strengthen the material structure. This prior reinforcement through crosslinking creates a more robust molecular network that cushions against thermal degradation and mechanical stress during expansion/contraction cycles at elevated temperatures, preventing tear propagation
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 resulting cold-shrink articles exhibit enhanced chemical resistance and tear properties, resisting tearing at 150°C for extended periods and showing minimal weight increase when exposed to diesel fuel or hydraulic fluid, ensuring durability and performance in demanding environments.
Implementation Method 1
The elastomeric composition may be crosslinked by exposure to an energy beam such as, for example, an electron beam or gamma radiation
Implementation Method 2
The support core is typically designed to collapse on demand and allow shrinkage of the cold-shrink article into contact with a substrate positioned inside the support core
Data Source
AI summary
An elastomeric composition that includes a fluorelastomer and an epichlorohydrin. The elastomeric composition can be formed into cold-shrink articles that are resistant to tearing at elevated temperatures.