Vulcanizable Rubber Composition with Microdispersed Polyolefin Resin
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Solution Overview
Problem
Current vulcanizable rubber compositions face limitations in reducing specific gravity while maintaining strength and roll workability due to poor compatibility of thermally expandable capsules with ethylene/α-olefin/nonconjugated polyene copolymer rubber, leading to reduced strength and compression set when attempting to decrease the amount of reinforcing agents with high specific gravity.
Innovation Solution
A vulcanizable rubber composition comprising ethylene/α-olefin/nonconjugated polyene copolymer rubber, microdispersed polyolefin resin, and a blowing agent, specifically a thermally expandable capsule with controlled particle diameter and compounding amounts, which allows for reduced specific gravity without compromising mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the amount of reinforcing agent with high specific gravity is reduced to decrease specific gravity, then weight reduction is achieved, but strength and roll workability deteriorate
Solution Approach 1:
The patent changes the physical state of the polyolefin resin from solid to microdispersed liquid phase in the rubber matrix. This parameter change allows the resin to be distributed uniformly at the molecular level, providing reinforcement without the need for high concentrations of traditional reinforcing agents, thus reducing specific gravity while maintaining strength.
Solution Approach 2:
The patent creates a composite material system comprising rubber, microdispersed polyolefin resin, and blowing agent. The polyolefin resin forms a fine dispersed phase within the rubber matrix, creating a multi-phase composite structure that provides both weight reduction and mechanical strength through the synergistic effect of the components.
2Weight of moving object
If thermally expandable capsule is incorporated in large amount to reduce specific gravity, then weight reduction is achieved, but strength and compression set deteriorate due to poor compatibility
Solution Approach 1:
The patent introduces polyolefin resin as an intermediary substance that is microdispersed throughout the rubber matrix. This intermediary phase improves the compatibility between the blowing agent capsules and the rubber matrix, allowing better stress distribution and maintaining mechanical properties even at high blowing agent concentrations.
Solution Approach 2:
The patent changes the dispersion state of the polyolefin resin to microdispersed phase with controlled particle size. This parameter change creates a fine distribution network that enhances interfacial adhesion between the blowing agent capsules and rubber matrix, improving compatibility and preventing deterioration of mechanical properties.
3Weight of moving object
If chemical blowing agent is used to achieve foaming, then specific gravity reduction is achieved, but large bubbles form between weather strip and metal core
Solution Approach 1:
The patent replaces chemical blowing agents with thermally expandable capsules as the foaming mechanism. This substitution eliminates the uncontrolled gas generation that causes large bubbles, as the capsules provide controlled, uniform expansion through thermal energy alone, resulting in fine and uniform cell structure.
Solution Approach 2:
The patent utilizes the phase transition of thermally expandable capsules from contracted to expanded state upon heating. This phase transition provides controlled and uniform gas generation throughout the rubber matrix, creating fine bubbles instead of large bubbles, as the expansion occurs progressively rather than through rapid chemical gas evolution.
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 achieves a specific gravity of 0.5 to 0.8, maintaining tensile strength, elongation, and compression set, while ensuring good roll workability and extrusion processability, enabling further weight reduction in rubber products.
Implementation Method 1
a thermally expandable capsule... the blowing agent (C) is present in an amount of from 2 to 6 parts by mass per 100 parts by mass of the ethylene/α-olefin/nonconjugated polyene copolymer rubber (A)
Implementation Method 2
the polyolefin resin (B) is microdispersed in a melted state in the ethylene/α-olefin/nonconjugated polyene copolymer rubber (A), the polyolefin resin (B) having an average dispersed particle diameter of 2 μm or less
Data Source
AI summary
The present invention provides a vulcanizable rubber composition containing (A) an ethylene/α-olefin/nonconjugated polyene copolymer rubber, (B) a polyolefin resin and (C) a blowing agent, wherein the polyolefin resin (B) is microdispersed in a melted state in the ethylene/α-olefin/nonconjugated polyene copolymer rubber (A), the polyolefin resin (B) having an average dispersed particle diameter of 2 μm or less, the polyolefin resin (B) is present in an amount of from 5 to 15 parts by mass per 100 parts by mass of the ethylene/α-olefin/nonconjugated polyene copolymer rubber (A), the blowing agent (C) is present in an amount of from 2 to 6 parts by mass per 10 parts by mass of the ethylene/α-olefin/nonconjugated polyene copolymer rubber (A), and the vulcanizable rubber composition has a specific gravity of from 1.05 to 1.15 and a Mooney viscosity (Vm) at 125° C. of from 25 to 55.