NBR-PVC Sealing Rubber Composition for Fuel Clogging and Ozone Resistance
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Solution Overview
Problem
Sealing rubber materials used in fuel tanks face issues with insolubilized substances causing clogging and ozone resistance when using NBR compositions, and excluding stearic acid and wax components leads to production failures and compromised ozone resistance.
Innovation Solution
A sealing rubber material is developed by cross-linking an NBR composition with a specific PVC content range of 15.70 to 17.50wt%, eliminating insolubilized substance-generating causative substances and maintaining ozone resistance and ejectability, achieved by blending NBR with PVC in a 55/45 to 50/50 ratio and incorporating suitable additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stearic acid and wax components are excluded from the NBR composition to prevent insolubilized substance generation, then fuel filter clogging is reduced, but ozone resistance deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by introducing PVC resin as a substitute for stearic acid and wax components. The specific parameter change is the PVC content ratio (15-30 wt%) which provides ozone resistance through the chlorine-containing polymer structure while avoiding the insolubilization problem of traditional additives in fuel environments.
Solution Approach 2:
The patent creates a composite rubber material by blending NBR with PVC resin. This composite structure combines the fuel resistance of NBR with the ozone resistance of PVC, achieving both requirements simultaneously. The composite formulation includes specific ratios of NBR (70-85 parts) and PVC (15-30 parts) to balance both properties.
2Reliability
If stearic acid is excluded from the blending formulation to reduce insolubilized substances, then fuel filter clogging is reduced, but ejectability from kneader deteriorates
Solution Approach 1:
The patent changes the lubricant parameter by replacing stearic acid with specific plasticizers (adipic acid esters, sebacic acid esters, or phthalic acid esters) at controlled amounts (5-20 parts per 100 parts polymer). This substitution maintains adequate ejectability while preventing insolubilized substance generation in fuel environments.
3Object-affected harmful factors
If conventional NBR composition with stearic acid and wax is used to maintain ozone resistance, then ozone resistance is preserved, but insolubilized substance generation increases causing fuel filter clogging
Solution Approach 1:
The patent fundamentally changes the composition parameters by eliminating stearic acid and wax components entirely, and introducing PVC resin (15-30 parts per 100 parts NBR) as the primary ozone protection mechanism. The plasticizer content is also optimized (5-20 parts) to maintain processing properties without contributing to insolubilization.
Solution Approach 2:
The patent develops a composite NBR-PVC rubber composition where PVC resin provides ozone resistance through its chlorine-containing polymer structure, while the NBR matrix maintains fuel resistance. This composite approach eliminates the need for stearic acid and wax additives that cause insolubilization in fuel environments.
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 restricts the generation of insolubilized substances, enhances ozone resistance, and maintains excellent compression set properties, ensuring the rubber material's performance in fuel tanks under varying temperatures and compression states.
Implementation Method 1
a sealing rubber material obtained by cross-linking an NBR composition
Data Source
AI summary
It is aimed at providing an NBR composition, which composition is substantially free of containment of an insolubilized substance-generating causative substance so as to prevent generation of an insolubilized substance due to extraction by a fuel while which composition is excellent in ozone resistance, ejectability from kneader, and the like, and which composition realizes a first compression set and a second compression set which are both 46% or less. The present invention provides an NBR composition comprising a polymer obtained by mixing an acrylonitrile-butadiene rubber (NBR) with polyvinyl chloride (PVC); wherein the NBR composition is obtained without blending an insolubilized substance-generating causative substance, or, in case of blending, by blending an insolubilized substance-generating causative substance at an upper limit of 0.15 parts by weight or less, into 100 parts by weight of the polymer having a PVC content of 15.70 to 17.50wt%.