Rubber Composition Mold Release Agent Silane Optimization
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Solution Overview
Problem
Rubber compositions used in tire treads face challenges in maintaining abrasion resistance and wet grip performance while preventing mold contamination, particularly due to the use of silica-rich formulations and adhesion imparting resins, which lead to increased mold contamination and productivity issues.
Innovation Solution
A rubber composition comprising specific amounts of stearic acid, metal salts of saturated fatty acids, mold release agents, silica, and silane coupling agents, optimized to minimize unreacted silane coupling agents and prevent mold contamination, while maintaining abrasion resistance and wet grip performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of silica and adhesion imparting resin is increased to improve wet grip performance and rolling resistance, then wet grip performance is improved, but mold contamination increases
Solution Approach 1:
A mold release agent is introduced as an intermediary substance between the rubber composition and the mold surface. This agent forms a release layer that prevents direct adhesion between the silica-rich rubber composition and the mold, thereby eliminating mold contamination while preserving the wet grip performance benefits of high silica content
Solution Approach 2:
The invention optimizes the concentration of mold release agent within a specific range (0.1 to 4.0 parts by mass per 100 parts of rubber composition) to achieve the optimal balance between preventing mold contamination and maintaining wet grip performance. This parameter optimization ensures sufficient release effect without compromising the adhesion properties provided by silica and resin
2Stability of the object's composition
If the amount of silane coupling agent is increased to improve silica dispersibility, then silica dispersibility is improved, but unreacted silane coupling agent remains and causes excessive adhesion on process roll and mold
Solution Approach 1:
The invention optimizes the concentration of silane coupling agent within a specific range (1.0 to 6.0 parts by mass per 100 parts of silica) to achieve complete reaction with silica surface hydroxyl groups. This parameter optimization ensures sufficient silica dispersibility while preventing excessive unreacted silane coupling agent that would cause adhesion problems
Solution Approach 2:
The mold release agent acts as a mediator that prevents direct contact between unreacted silane coupling agent and the mold surface. This intermediary layer eliminates the harmful adhesion effects of unreacted silane coupling agent while preserving the beneficial silica dispersibility improvements
3Reliability
If the amount of adhesion imparting resin is increased to improve wet grip performance, then wet grip performance is improved, but mold contamination increases
Solution Approach 1:
The mold release agent serves as an intermediary substance that prevents direct adhesion between the resin-containing rubber composition and the mold surface. This intermediary layer eliminates mold contamination caused by resin adhesion while preserving the wet grip performance benefits of increased resin content
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 prevents mold contamination, maintains abrasion resistance, and ensures consistent wet grip performance, improving productivity and tire quality.
Implementation Method 1
it is known that a silane coupling agent is compounded for improving dispersibility of silica, the silane coupling agent is known to, if the number of kneading is small and/or kneading time is short, or a deaeration process (process of promoting a coupling reaction by evacuating ethanol or water piled up in a container during kneading with a Banbury mixer for a few seconds) is not performed, remain in the kneaded product as a unreacted monomer
Implementation Method 2
the rubber composition comprises 2.5 to 8.0 parts by mass of at least one selected from the group consisting of: stearic acid, a metal salt of saturated fatty acid and a mold release agent
Data Source
AI summary
An object of the present invention is to provide a rubber composition which can prevent mold contamination while maintaining abrasion resistance and wet grip performance, and a tire which has a tread composed of the rubber composition. The rubber composition of the present invention comprises a predetermined amount of at least one selected from the group consisting of stearic acid, a metal salt of saturated fatty acid and a specific mold release agent, a specific resin, silica and a silane coupling agent, based on a diene rubber component, where an amount of an unreacted silane coupling agent in the rubber composition before vulcanization is within a predetermined range.