Nitrile Rubber Composition for Ozone-Resistant Auto Seals
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Solution Overview
Problem
Rubber molded products used in automobile components face deterioration due to ozone exposure, requiring enhanced ozone resistance to meet increasing performance demands.
Innovation Solution
A rubber composition comprising 100 parts of nitrile rubber with 19-30% acrylonitrile units, 10-300 parts of white filler, 0.3-10 parts of paraffin wax, 0.5-5 parts of dithiocarbamic acid salt-based antioxidant, and optional microcrystalline wax-based antioxidant, along with a plasticizer and carbon black, is developed to achieve excellent ozone resistance through vulcanization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nitrile rubber composition is used, then basic sealing function is achieved, but ozone resistance is insufficient
Solution Approach 1:
The patent introduces a specific antioxidant (dithiocarbamic acid salt-based) as an intermediary substance that mediates between the rubber matrix and ozone. This antioxidant acts as a sacrificial protector, reacting with ozone before it can attack the rubber polymer chains, thereby preventing oxidation deterioration while maintaining the rubber's sealing function.
Solution Approach 2:
The patent optimizes the acrylonitrile content parameter within a specific range (19-30 mass%) to achieve the right balance between ozone resistance and other performance characteristics. By controlling this compositional parameter, the rubber gains sufficient polarity and chemical resistance while maintaining adequate elasticity and processing properties.
2Reliability
If white filler is added to enhance ozone resistance, then oxidation resistance improves, but processing difficulty increases
Solution Approach 1:
The patent specifies a controlled amount of white filler (10-300 parts per 100 parts of rubber) to achieve sufficient oxidation resistance without excessive filler loading. This parameter optimization ensures that the filler provides protective function while maintaining reasonable processing characteristics and avoiding overly stiff or difficult-to-process compound.
Solution Approach 2:
The patent creates a composite rubber composition by combining nitrile rubber with white filler particles dispersed throughout the matrix. This composite structure provides the protective barrier against oxidation while the rubber matrix maintains flexibility and processability, achieving a balance between enhanced durability and manufacturability.
3Ease of operation
If paraffin wax is added to improve surface properties, then handling characteristics improve, but crosslinking uniformity deteriorates
Solution Approach 1:
The patent controls the paraffin wax content within a specific range (0.3-10 parts per 100 parts of rubber) to provide sufficient surface lubricity and handling improvement without excessive wax interference. This parameter control ensures that the wax migrates to the surface where it aids handling, while the bulk composition maintains uniform crosslinking characteristics.
Solution Approach 2:
The patent allows paraffin wax to concentrate at the surface region of the rubber compound, providing local improvement in handling characteristics at the interface with molds or processing equipment. The bulk interior maintains relatively uniform composition for consistent crosslinking, achieving spatial differentiation of properties to satisfy both handling and manufacturing precision requirements.
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 rubber composition effectively enhances the ozone resistance of molded products, making them suitable for use in automobile components such as seals and gaskets, while maintaining heat resistance and handling properties.
Implementation Method 1
one of the causes of the deterioration of a rubber molded product includes oxidation deterioration due to ozone present in air
Implementation Method 2
it has been found that when a rubber composition contains both a white filler and a paraffin wax, the paraffin wax migrates to the surface of a rubber molded product during storage
Data Source
AI summary
A rubber composition includes: 100 parts by mass of a nitrile rubber (A); 10 to 300 parts by mass of a white filler (B); 0.3 to 10 parts by mass of a paraffin wax (C); and 0.5 to 5 parts by mass of a dithiocarbamic acid salt-based antioxidant (D). The nitrile rubber (A) has a content of an acrylonitrile unit of 19 to 30 mass %, and the paraffin wax (C) has a melting point of 45 to 100° C.