Silated Core Polysulfides for Filled Elastomer Bonding
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Solution Overview
Problem
Existing silane coupling agents for mineral-filled elastomers have low reactivity due to steric hindrance, leading to weak links between the polymer and silica, resulting in poor wear characteristics and high rolling resistance in rubber applications.
Innovation Solution
Development of silated core polysulfides with a Y-core structure and multiple polysulfide groups attached to a primary carbon atom, allowing for multiple points of sulfur attachment to the polymer and filler, reducing steric hindrance and enhancing reactivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polysulfide groups are attached directly to aromatic or cyclic aliphatic cores, then the coupling agent can bond to both silica and polymer, but steric hindrance reduces reactivity with the polymer
Solution Approach 1:
The patent applies local quality by differentiating the chemical environment at different locations within the coupling agent molecule. The polysulfide groups are positioned in specific local environments (attached to sp3 hybridized carbon atoms with appropriate substitution patterns) that optimize their reactivity with polymer while maintaining bonding to the core structure. This localized optimization of chemical environment resolves the contradiction between maintaining coupling effectiveness and enhancing reactivity.
Solution Approach 2:
The patent changes key chemical parameters of the coupling agent structure: the hybridization state of carbon atoms (from sp2 in aromatic/cyclic structures to sp3 in acyclic structures), the substitution pattern (primary vs secondary vs tertiary carbon), and the overall molecular geometry. These parameter changes transform the coupling agent from a low-reactivity state (sterically hindered) to a high-reactivity state while preserving its dual bonding capability.
2Device complexity
If simple bis polysulfide silanes are used with short methylene chains, then the structure is simpler, but the single C-S and S-S linkages create weak links that contribute to wear
Solution Approach 1:
The patent applies segmentation by dividing the coupling agent into distinct functional segments: a core structure segment, multiple polysulfide chain segments, and multiple silane segments. Each segment performs a specific function, and the modular architecture allows for multiple independent bonding points. This segmentation replaces the single weak linkage with multiple distributed linkages, significantly improving overall bond strength and wear resistance.
Solution Approach 2:
The patent creates a composite molecular structure that combines multiple chemical functionalities (polysulfide groups, silane groups, hydrocarbon chains) into a single coupling agent molecule. This composite structure integrates the benefits of each functional group: polysulfide groups for polymer bonding, silane groups for silica bonding, and hydrocarbon chains for structural flexibility. The composite nature allows simultaneous achievement of multiple bonding functions with enhanced overall strength.
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 silated core polysulfides improve the physical properties and wear characteristics of mineral-filled elastomers, including reduced rolling resistance in tire applications, by providing multiple points of attachment and increased reactivity.
Implementation Method 1
hydrolysis of the alkoxysilyl groups and subsequent condensation with silica hydroxyl groups
Implementation Method 2
hydrolysis of the alkoxysilyl groups and subsequent condensation with silica hydroxyl groups
Implementation Method 3
chemical bond formation between the silane sulfur and the polymer
Implementation Method 4
The reaction of the silane sulfur with the polymer occurs when the S-S bonds are broken and the resulting fragment adds to the polymer
Data Source
Figure 1
AI summary
This invention relates to novel sulfur-containing silane coupling agents, and organic polymers containing carbon-carbon double bonds. These novel silanes can be carried on organic and inorganic fillers. The invention also relates to articles of manufacture, particularly tires, made from the elastomer compositions described herein.