NBR Rubber-Metal Laminate Composition for Protrusion and Sealing
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Solution Overview
Problem
Existing rubber laminated metal compositions face challenges in maintaining protrusion properties and sealing efficiency while avoiding increased hardness, which affects the vibration control characteristics of brake shim materials.
Innovation Solution
An NBR composition incorporating 1 to 3 parts by weight of sulfur and 1 to 15 parts by weight of a disulfide compound (e.g., 4,4′-dithiodimorpholine) per 100 parts by weight of NBR, which enhances protrusion properties without increasing hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the compounding amount of sulfur is increased to enhance crosslinking density, then protrusion properties are improved, but rubber hardness increases and kneading processability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by introducing a disulfide compound (specifically 4,4′-dithiodimorpholine) as a vulcanizing agent alternative or supplement to traditional sulfur. This parameter change enables achieving the desired crosslinking density and protrusion properties without the adverse effect of increased rubber hardness, thereby maintaining kneading processability while improving the target property.
2Strength
If the compounding amount of filler such as carbon black or silica is increased to improve protrusion properties, then protrusion properties are improved, but rubber hardness increases and sealing properties are lowered
Solution Approach 1:
The patent modifies the vulcanizing agent composition by incorporating a disulfide compound (4,4′-dithiodimorpholine) in specific amounts (0.1 to 5 parts by weight based on 100 parts of NBR). This parameter change in the chemical composition enables improvement of protrusion properties through enhanced crosslinking without requiring excessive filler addition, thereby preventing the associated increase in hardness that would compromise sealing properties.
3Strength
If the compounding amount of morpholine disulfide is increased to enhance protrusion properties, then protrusion properties are improved, but premature vulcanization occurs causing scorching phenomenon
Solution Approach 1:
The patent optimizes the compounding amount of morpholine disulfide (or 4,4′-dithiodimorpholine) to a specific range (0.1 to 5 parts by weight based on 100 parts of NBR). This parameter optimization ensures sufficient crosslinking for improved protrusion properties while preventing premature vulcanization and scorching, thereby maintaining reliable vulcanization control.
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
This solution effectively improves protrusion properties without compromising kneading processability or sealing properties, maintaining the vibration control characteristics of brake shim materials.
Implementation Method 1
comprising 1 to 3 parts by weight of sulfur and 1 to 15 parts by weight of a disulfide compound represented by the general formula RN—S—S—NR based on 100 parts by weight of NBR
Data Source
AI summary
An NBR composition for rubber laminated metal having 1 to 3 parts by weight of sulfur and 1 to 15 parts by weight of a disulfide compound such as 4,4′-dithiodimorpholine or dithiodicaprolactam represented by the general formula RN—S—S—NR (wherein RN is a cyclic linking group formed together with the N atom bonded to the S atom), based on 100 parts by weight of NBR. The rubber composition that can improve the protrusion properties of a rubber layer when used for, for example, a gasket or a brake shim material that is a laminated composite metal laminated with another metal plate.