Silica-Filled Rubber Composition With Better Kneading Processability
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Solution Overview
Problem
Existing rubber compositions containing highly modified solution-polymerized styrene-butadiene copolymers and fine fillers like silica face kneading difficulties, leading to increased Mooney viscosity, reduced productivity, and poor dispersion, which hinder the production of tires with improved low fuel consumption and mechanical strength.
Innovation Solution
Incorporating a specific liquid conjugated diene-based polymer with a modified solution-polymerized styrene-butadiene copolymer and silica filler, optimized for content ratios and surface area, to enhance processability and elastic modulus in rubber compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a highly modified solution-polymerized styrene-butadiene copolymer with high Si-containing functional group concentration is used to improve filler dispersibility and low fuel consumption performance, then the dispersibility of silica is improved, but the Mooney viscosity increases remarkably during kneading and processability deteriorates
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance between the modified S-SBR and silica filler. The silane coupling agent contains both organofunctional groups that interact with the rubber polymer and inorganic functional groups that bond with silica, thereby mediating the interface between rubber and filler to improve dispersibility without causing excessive viscosity increase during kneading
2Strength
If fine silica with small particle size is used to increase tire material elasticity and cope with thinning, then the elastic modulus is improved, but the kneading difficulty increases and productivity deteriorates
Solution Approach 1:
The silane coupling agent is pre-added to the rubber composition before the fine silica is introduced during kneading. This preliminary action prepares the rubber matrix with appropriate surface properties and viscosity characteristics, enabling the fine silica to be incorporated more easily without causing excessive kneading difficulty or productivity loss
3Loss of energy
If a highly modified solution-polymerized styrene-butadiene copolymer is used to improve low fuel consumption performance, then the heat generation is reduced, but the sheet formed after kneading is easy to tear and manufacturing reliability decreases
Solution Approach 1:
The silane coupling agent serves as a mediator that strengthens the interfacial bonding between the modified S-SBR and silica filler. This improved interface prevents sheet tearing during subsequent processing operations while maintaining the low heat generation characteristics of the highly modified rubber composition
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 rubber composition achieves improved processability, low heat generation, and enhanced elastic modulus, resulting in tires with better low fuel consumption performance and mechanical strength.
Implementation Method 1
a liquid conjugated diene-based polymer (C) having a weight average molecular weight in a range of 3,000 to 200,000
Implementation Method 2
a modified solution-polymerized styrene-butadiene copolymer (A1) having a Si-containing functional group... excellent in interaction with carbon black or silica
Data Source
AI summary
Provided are: a tire that is produced such that at least a portion thereof is formed from a rubber composition or a crosslinked product of the rubber composition even when the rubber composition contains a highly modified solution-polymerized styrene-butadiene copolymer having a specific content of Si derived from a Si-containing functional group as a solid rubber, which is expected to be improved in low fuel consumption performance, and further contains a fine filler (for example, fine silica) as a filler, the processability is improved, and further the rubber composition or a crosslinked product of the rubber composition has an inherent good elastic modulus; a tire tread formed at least partially using the rubber composition; and a pneumatic tire formed at least partially using the rubber composition. A rubber composition, containing 60 to 150 parts by mass of silica (B1) as a filler (B) and 5 to 30 parts by mass of a liquid conjugated diene-based polymer (C) having a weight average molecular weight in a range of 3,000 to 200,000 with respect to 100 parts by mass of a solid rubber (A) containing 60 mass% or more of a modified solution-polymerized styrene-butadiene copolymer (A1) having a Si-containing functional group, in which a content of Si derived from the Si-containing functional group contained in the modified solution-polymerized styrene-butadiene copolymer (A1) is 220 to 800 ppm, and the silica (B1) has a specific surface area (CTAB) of 180 to 500 m2/g.