Crosslinkable Acrylic Rubber Composition for Thermal Oxidation Stability
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Solution Overview
Problem
Existing crosslinkable acrylic rubber compositions fail to adequately suppress softening and hardening degradation during thermal oxidative processes, leading to a decrease in mechanical strength, and require additional steps that increase production costs.
Innovation Solution
A crosslinkable acrylic rubber composition comprising acrylic rubber with carbamic acid ester and carboxyl groups, phenothiazine-based antioxidants, and a crosslinking accelerator, which forms a specific crosslinked structure that minimizes degradation and eliminates the need for additional crosslinking agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If amine-based antioxidants are used to improve heat resistance, then thermal stability is improved, but mechanical strength decreases due to thermal oxidative degradation
Solution Approach 1:
The patent combines phenothiazine-based antioxidant and crosslinking accelerator functions into a single compound structure. This merged molecule simultaneously provides thermal oxidation resistance and enables crosslinking to maintain mechanical strength at high temperatures, resolving the contradiction between heat resistance improvement and mechanical strength preservation.
Solution Approach 2:
The invention creates a composite functional material by incorporating both antioxidant and crosslinking accelerator capabilities into one compound. This composite approach allows the material to exhibit both thermal stability and structural integrity under thermal oxidative conditions, addressing the limitation of conventional single-function additives.
2Strength
If crosslinking structure is formed to maintain mechanical strength, then heat resistance is improved, but softening degradation occurs in early stage of thermal oxidative degradation
Solution Approach 1:
The phenothiazine-based compound is incorporated into the rubber composition before crosslinking occurs. This preliminary presence of the antioxidant function prevents softening degradation during the early stages of thermal oxidative degradation, protecting the crosslinking structure from compositional instability before the crosslinking is fully established.
3Duration of action of stationary object
If phenothiazine-based antioxidant is used to suppress hardening degradation, then long-term stability is improved, but dispersibility in rubber decreases
Solution Approach 1:
The invention modifies the molecular structure parameters of the phenothiazine-based compound by introducing specific substituents (R1-R6 groups) that balance polarity and molecular size. This parameter optimization enables sufficient dispersibility in the rubber matrix while maintaining the long-term antioxidant activity needed to suppress hardening degradation during service.
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 effectively suppresses both early-stage softening and late-stage hardening degradation, maintaining mechanical strength and reducing production complexity by integrating the antioxidant directly into the rubber structure.
Implementation Method 1
the carbamic ester group is decomposed by heat and the action of a nitrogen-containing basic organic compound to liberate the amino group
Implementation Method 2
reacts with the active site derived from an α,β-unsaturated carboxylic acid monomer to form a complementary crosslinked structure
Implementation Method 3
phenothiazine-based antioxidants... suppresses both early-stage softening and late-stage hardening degradation
Data Source
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AI summary
A crosslinkable acrylic rubber composition comprising: (A) acrylic rubber containing a carbamic acid ester group and a carboxyl group; (B) a phenothiazine-based antioxidant represented by the following general formula [I]: [wherein R3 is a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or an acyl group represented by the following general formula: (wherein R4 is a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms), and R5 is an aralkyl group having 7 to 20 carbon atoms]; and (C) a crosslinking accelerator. The crosslinkable acrylic rubber composition that can suppress significant softening degradation of an acrylic rubber crosslinked product observed in the early stage of thermal oxidative degradation and hardening degradation observed in the later stage thereof, and that can minimize the decrease in its mechanical strength.