Diene Elastomer Pendant Groups Prevent Plasticizer Exudation
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Solution Overview
Problem
Rubber compositions for tires face compatibility issues and exudation problems due to the use of plasticizers, which affect the glass transition temperature and performance over time.
Innovation Solution
A diene elastomer with pendant groups of the formula *-SiR1R2-A-B, where R1 and R2 are alkyl or aryl groups, A is a C3-C35 aliphatic radical, and B is a C1-C6 hydrocarbon radical, is used, which is incorporated into the elastomer chain through hydrosilylation, increasing compatibility and preventing plasticizer crystallization and exudation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If plasticizers are added to rubber compositions to shift glass transition temperature and improve processability, then the elastomer becomes more compatible and easier to process, but the plasticizer may crystallize or exude from the material over time
Solution Approach 1:
The patent combines the plasticizer function directly into the elastomer chain by grafting pendant groups containing plasticizing moieties (such as ester groups) onto the polymer backbone. This merging eliminates the need for separate plasticizer additives, preventing crystallization and exudation while maintaining the desired glass transition temperature and processability benefits.
Solution Approach 2:
The invention creates a composite structure where the elastomer chain incorporates both the polymer backbone and plasticizing functional groups as an integrated unit. This composite approach allows the material to exhibit both structural integrity and plasticizing effect simultaneously, with the pendant groups distributed along the chain providing continuous plasticization without phase separation.
2Temperature
If plasticizers are added to modify glass transition temperature, then the desired thermal properties are achieved, but compatibility issues arise between the plasticizer and elastomer
Solution Approach 1:
By grafting plasticizing groups directly onto the elastomer chain, the invention merges the plasticizer and polymer into a single compatible system. The pendant groups are chemically bonded to the backbone, ensuring uniform distribution and thermodynamic compatibility, thereby achieving precise control over glass transition temperature without phase separation or incompatibility issues.
3Ease of operation
If plasticizers are used to improve processability, then uncured state handling is enhanced, but exudation towards the outside of the tire or internal mixtures occurs over time
Solution Approach 1:
The invention merges the plasticizer functionality into the elastomer chain itself through pendant groups, creating an intrinsic plasticizing effect. Since the plasticizing groups are covalently bonded to the polymer backbone, they cannot migrate or exude from the material, eliminating plasticizer loss while maintaining improved processability in the uncured state.
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 solution enhances the compatibility of the plasticizer with the elastomer, reduces crystallization, and prevents exudation, maintaining performance and properties of the tire over time by stabilizing the glass transition temperature and reducing plasticizer loss.
Implementation Method 1
The elastomer can in particular be obtained by hydrosilylation of an E diene elastomer, by reacting said E diene elastomer with a hydrogen silane of the following formula (II): H-SiR1R2-A-B, in the presence of a hydrosilylation catalyst.
Data Source
AI summary
The present invention relates to a diene elastomer, characterised in that it includes units from dienes distributed along the chain having a pendant group of the following formula (I): *-SiR1R2-A- B, in which A and B are such that the melting temperature of the non-hydrosilylated analogue, H-A-B, is less than 70°C, and the elastomer includes 10 to 40 wt % of pendant groups of formula (I) in relation to the total weight of the elastomer. The present invention also relates to a method for preparing such a diene elastomer and to the compositions including same, in particular rubber compositions for tyres.