Pneumatic Tire Bead Reinforcing Layer Antioxidant Gradient
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Solution Overview
Problem
Conventional bead reinforcing layers in pneumatic tires suffer from antioxidant migration from adjacent members, leading to performance deteriorations such as increased heat generation, decreased rigidity, and reduced steering stability.
Innovation Solution
A pneumatic tire design where the bead reinforcing layer and adjacent members contain a specific range of amine type antioxidants, with a content ratio of 0.3 to 8 parts by mass in the bead reinforcing layer and 3 to 8 parts by mass in adjacent members, along with specific rubber composition properties like tan δ and E* values, to suppress antioxidant migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adjacent members (sidewalls or clinches) containing large amount of amine type antioxidant are disposed adjacent to the bead reinforcing layer to improve ozone resistance, then crack resistance against ozone cracks is improved, but antioxidant migrates from the adjacent member to the bead reinforcing layer causing performance deterioration
Solution Approach 1:
The patent applies local quality by giving different antioxidant contents to different parts of the tire structure. The bead reinforcing layer is assigned a specific antioxidant content range (0.3 to 8 parts by mass per 100 parts by mass of rubber component), while adjacent members are assigned higher content, creating a controlled gradient that prevents excessive migration while maintaining ozone resistance where needed.
Solution Approach 2:
The patent resolves the contradiction by changing the parameter of antioxidant content distribution. By specifying that the ratio B/A (where B is antioxidant content in adjacent member and A is antioxidant content in bead reinforcing layer) should satisfy 3 ≤ B/A ≤ 8, the patent optimizes the parameter to prevent harmful migration while maintaining protective function in adjacent members.
2Loss of substance
If antioxidant content in bead reinforcing layer is increased to suppress migration, then antioxidant migration is reduced, but heat generation increases and rigidity decreases
Solution Approach 1:
The patent optimizes the antioxidant content parameter in the bead reinforcing layer to a specific range (0.3 to 8 parts by mass per 100 parts by mass of rubber component). This parameter optimization prevents excessive antioxidant accumulation that would cause heat generation and rigidity loss, while still providing sufficient antioxidant to suppress migration from adjacent members.
3Loss of substance
If antioxidant content in bead reinforcing layer is increased to suppress migration, then antioxidant migration is reduced, but steering stability decreases
Solution Approach 1:
The patent maintains steering stability by controlling the antioxidant content parameter in the bead reinforcing layer within the range of 0.3 to 8 parts by mass per 100 parts by mass of rubber component. This parameter control prevents excessive antioxidant content that would degrade the rubber composition and affect steering stability, while still suppressing harmful migration.
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 tire exhibits suppressed antioxidant migration, maintaining high rigidity and steering stability while reducing heat generation, thereby enhancing durability and fuel efficiency.
Implementation Method 1
the bead reinforcing layer and adjacent members adjacent to the bead reinforcing layer are each composed of a rubber composition containing an amine type antioxidant
Implementation Method 2
it is necessary to maintain crack resistance against ozone cracks and the like for a long period of time
Implementation Method 3
the rubber composition constituting the bead reinforcing layer has a tan δ at 70° C. of 0.14 or less
Data Source
AI summary
A pneumatic tire having a tread, a sidewall, a bead portion having a bead core, a bead reinforcing layer reinforcing the bead portion, and a carcass ply moored on a bead core of the bead portion, wherein the bead reinforcing layer and adjacent members adjacent to the bead reinforcing layer are each composed of a rubber composition containing an amine type antioxidant, 0.3 to 8 parts by mass of the amine type antioxidant is contained in the bead reinforcing layer based on 100 parts by mass of the rubber component, and the adjacent member adjacent to the bead reinforcing layer and the bead reinforcing layer satisfy the following formula:2≤B/A≤8A: Content (wt %) of amine type antioxidant in bead reinforcing layer.B: Content (wt %) of amine type antioxidant in the adjacent member.