Silica-Modified Rubber Composition for Tire Tread
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Solution Overview
Problem
Conventional rubber compositions for tire treads, despite containing modified polymers and mercaptosilane, fail to achieve optimal low rolling resistance, wet performance, and processability due to silica dispersion issues and high crosslinking.
Innovation Solution
A rubber composition incorporating a specific modified conjugated diene rubber, silica, and a polysiloxane silane coupling agent with a defined formula, which enhances silica dispersion and interaction, thereby improving wet performance, rolling resistance, and processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silica is simply added to the rubber component, then the rubber composition can be prepared, but the silica is not dispersed properly and the effect of reducing rolling resistance or improving wet performance cannot be sufficiently achieved
Solution Approach 1:
The patent uses a silane coupling agent as an intermediary substance between silica and rubber component. The silane coupling agent has affinity with both silica and rubber, facilitating proper dispersion of silica in the rubber matrix and enabling the silica to effectively reduce rolling resistance and improve wet performance.
Solution Approach 2:
The patent modifies the chemical parameters by introducing a silane coupling agent that changes the interaction parameters between silica and rubber. This chemical modification enables better compatibility and dispersion of silica particles in the rubber component.
2Stability of the object's composition
If a silane coupling agent is used to disperse silica, then silica dispersion improves, but crosslinking (rubber burning) occurs at the storage stage or before vulcanization
Solution Approach 1:
The patent applies silane modification to the rubber component in advance during compounding, but controls the conditions so that the silane coupling agent does not react with silica until the vulcanization stage. This preliminary preparation without premature reaction maintains scorch resistance while enabling good silica dispersion at the appropriate time.
Solution Approach 2:
The patent uses the silane-modified rubber component as a protective measure that prevents premature crosslinking. The modified rubber acts as a cushion against early crosslinking reactions, maintaining processability during storage and processing while ensuring proper silica interaction during vulcanization.
3Reliability
If conventional mercaptosilane is used, then silica can react with the rubber component, but the low rolling resistance, wet performance, and processability do not satisfy the currently required levels
Solution Approach 1:
The patent changes the chemical structure parameters of the silane coupling agent by introducing a specific molecular structure with silicon atoms and appropriate functional groups. This structural parameter change improves both the affinity with silica and the compatibility with rubber, achieving better wet performance, lower rolling resistance, and improved processability simultaneously.
Solution Approach 2:
The patent creates a composite system consisting of silane-modified rubber component, silica, and coupler. This composite material approach combines the advantages of each component to achieve superior overall performance in wet performance, rolling resistance, and processability that cannot be achieved with conventional mercaptosilane alone.
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 excellent wet performance, low rolling resistance, and improved processability by effectively dispersing silica and maintaining vulcanization stability, leading to enhanced tire performance.
Implementation Method 1
a silane coupling agent; the silane coupling agent being a polysiloxane represented by the following formula (1)... the modified part having a functional group which interacts with the silica
Implementation Method 2
the modified part having a functional group which interacts with the silica... capable of reacting with silica
Data Source
Figure 1
AI summary
The present invention provides a rubber composition for a tire tread having excellent wet performance and low rolling resistance when formed into a tire as well as excellent processability. The present invention is a rubber composition for a tire tread containing a diene rubber component containing at least 20 mass% of a modified conjugated diene rubber, a silica, and a silane coupling agent; the modified conjugated diene rubber having at least one modified part and at least one conjugated diene rubber part; the conjugated diene rubber part having a conjugated diene copolymer block and an isoprene block containing from 70 mass% to 100 mass% of isoprene units in each conjugated diene rubber part; the modified part bonding to an end of the conjugated diene rubber part; the modified part having a functional group which interacts with the silica; the silane coupling agent being a polysiloxane represented by the following formula (1); a content of the silica being from 60 to 200 parts by mass per 100 parts by mass of the diene rubber component; and a content of the silcane coupling agent being from 1.0 to 20 mass% of the content of the silica; and a pneumatic tire having tire treads formed using the rubber composition. (A)a(B)b(C)c(D)d(R1)eSiO(4-2a-b-c-d-e)/2 (1) [Formula (1) is an average composition formula, and in formula (1), A is a divalent organic group containing a sulfide group; B is a monovalent hydrocarbon group having from 5 to 10 carbon atoms; C is a hydrolyzable group; D is an organic group containing a mercapto group; R1 is a monovalent hydrocarbon group having from 1 to 4 carbon atoms; and a to e satisfy the relational expressions 0≤a<1, 0≤b<1, 0<c<3, 0<d <1, 0≤ e<2, and 0<2a+b+c+d+e<4. However, either a or b is not 0.]