Silicone Rubber Bladder for Tire Vulcanization
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Solution Overview
Problem
Conventional bladders for tire production face issues such as low strength, short service life, and the need for releasing agents during vulcanization, which affect tire quality and increase the number of steps, while also limiting the repetitive use of the bladder.
Innovation Solution
A silicone rubber composition comprising a straight-chain diorganopolysiloxane, organohydrogenpolysiloxane, dry silica, and a platinum group metal catalyst is used, providing improved strength, durability, and eliminating the need for releasing agents during tire building and vulcanization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional silicone rubber formulations are used for tire building bladders, then the bladder can be used for assembling green tires, but the cured silicone has low strength and short service life due to easy crack formation on the surface
Solution Approach 1:
The patent changes the chemical composition parameters of the silicone rubber by incorporating polyhydrosiloxane (5-50 parts by mass per 100 parts by mass of vinyl-containing polysiloxane) and controlling the molecular weight and structure of the base polymer. This compositional parameter change results in improved tear strength (not less than 30 kN/m) and extended service life through superior crack resistance while maintaining the required hardness and elasticity for tire building applications
Solution Approach 2:
The patent creates a composite silicone rubber material by combining vinyl-containing polysiloxane with polyhydrosiloxane and crosslinking agents. This composite formulation integrates the advantages of both components: the vinyl groups provide crosslinking sites for high strength, while the polyhydrosiloxane contributes to elongation and crack resistance, achieving tear strength of not less than 30 kN/m and service life exceeding conventional bladders
2Reliability
If butyl rubber formulations are used for tire vulcanization bladders, then heat resistance and elongation are ensured, but releasing agents must be applied to both the bladder surface and innerliner to prevent adhesion, increasing the number of steps and potentially affecting tire quality
Solution Approach 1:
The patent extracts and eliminates the releasing agent step from the tire vulcanization process by developing a silicone rubber bladder formulation that inherently prevents adhesion between the bladder and green tire. The specific composition with polyhydrosiloxane and controlled crosslinking creates a non-sticking surface that maintains reliability during vulcanization without requiring additional releasing agent application steps
Solution Approach 2:
The silicone rubber bladder formulation provides self-release functionality through its inherent material properties. The combination of polyhydrosiloxane and crosslinking agents creates a surface that naturally resists adhesion to the green tire during vulcanization, allowing the bladder to serve itself as both the structural element and the release mechanism, thereby eliminating the need for separate releasing agent applications
3Productivity
If conventional bladders are used for repeated vulcanization cycles, then the process can be maintained, but the repetitive use limit is only about 450 times due to material degradation and adhesion issues
Solution Approach 1:
The patent optimizes the crosslinking density and molecular structure parameters of the silicone rubber by controlling the ratio of vinyl-containing polysiloxane to polyhydrosiloxane and selecting appropriate crosslinking agents. This results in a balanced network structure that provides both durability for repeated use and flexibility to prevent crack formation, extending the repetitive use limit beyond 450 times while maintaining material reliability
Solution Approach 2:
The patent employs a composite silicone rubber system combining vinyl-containing polysiloxane, polyhydrosiloxane, and crosslinking agents that work synergistically. The vinyl groups form crosslinked networks for structural integrity and durability, while the polyhydrosiloxane provides chain flexibility and crack resistance. This composite structure enables the bladder to withstand repeated vulcanization cycles (exceeding 450 times) without degradation of mechanical properties or adhesion failures
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 silicone rubber composition achieves a higher tear strength, tensile strength, and elongation, extending the service life of the bladder and improving tire quality by preventing adhesion issues without the use of releasing agents, with a service life of over 500 times for passenger car tires.
Implementation Method 1
a straight-chain diorganopolysiloxane including two or more alkenyl groups bonded to silicon atoms in its molecule and having a weight average molecular weight of 300000 - 1200000; and 0.01-10 parts by mass of an organohydrogenpolysiloxane
Data Source
AI summary
A bladder for tire production comprises a silicone rubber composition comprising (A) 100 parts by mass of a specified straight-chain diorganopolysiloxane; (B) 0.01-10 parts by mass of a specified organohydrogenpolysiloxane; (C) 20-80 parts by mass of a dry silica; and (D) 0.1-1000 ppm of a platinum group metal catalyst as converted to a weight of a platinum group metal per a total mass of the components (A) and (B).