Low Vinyl Copolymers via Potassium Alcoholate Catalyst
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Solution Overview
Problem
Existing methods for producing random copolymers of conjugated dienes and vinyl aromatic monomers result in high vinyl content and block styrene, which adversely affect the elastic-hysteresis characteristics of rubber products, such as rolling resistance and wet grip, due to the use of alkali metal salts and polar additives that lead to gel formation and equipment clogging.
Innovation Solution
The method involves copolymerization of conjugated dienes and vinyl aromatic monomers using an organolithium initiator in the presence of a potassium alcoholate and an electron donor system, followed by modification with cyclosiloxanes or lactams, at temperatures between 70 to 130°C, to achieve a low vinyl content and random distribution of monomer units, reducing polymerization time and gel formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkali metal salts and polar additives are used in copolymerization, then polymerization can proceed, but high vinyl content and block styrene are formed which adversely affect elastic-hysteresis characteristics
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by using organolithium compounds combined with specific additives (amino alcohols, ethers, esters) instead of conventional alkali metal salts. This parameter change enables precise control of vinyl content (1-10 mol%) and eliminates block styrene formation, thereby improving elastic-hysteresis characteristics while maintaining manufacturability
Solution Approach 2:
The patent introduces intermediary substances (amino alcohols, ethers, esters) that mediate between the organolithium catalyst and monomers. These intermediaries control the polymerization process to achieve random copolymer structure with low vinyl content, preventing the formation of block styrene and improving rubber elasticity without requiring harsh alkali metal salts
2Ease of manufacture
If conventional catalyst systems are used, then copolymerization can be performed, but gel formation and equipment clogging occur
Solution Approach 1:
The patent extracts and eliminates the harmful components (alkali metal salts and polar additives that cause gel formation) from the catalyst system. By using organolithium compounds with specific organic additives, the process achieves clean polymerization without gel formation or equipment clogging, maintaining ease of manufacture while removing harmful byproducts
Solution Approach 2:
The patent employs disposable-like catalyst systems where organolithium compounds are used in controlled amounts and consumed during polymerization. The specific additives (amino alcohols, ethers, esters) act as single-use mediators that control the reaction and are incorporated into the polymer structure or remain as harmless residues, preventing gel formation without requiring complex catalyst recovery systems
3Productivity
If high vinyl content copolymers are produced, then polymerization is easier, but rolling resistance and wet grip properties deteriorate
Solution Approach 1:
The patent changes the vinyl content parameter from conventional high levels (typically >15 mol%) to low levels (1-10 mol%) by modifying the catalyst system. This parameter change dramatically improves rolling resistance and wet grip properties while the organolithium-based catalyst maintains high polymerization efficiency, eliminating the trade-off between productivity and performance
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
This approach results in copolymers with excellent affinity to silica and carbon fillers, improving the elastic-hysteresis properties of rubber products, including reduced rolling resistance and enhanced wet grip, while simplifying the polymerization process and eliminating equipment clogging issues.
Implementation Method 1
copolymerization of conjugated dienes and vinyl aromatic monomers using an organolithium initiator
Implementation Method 2
presence of a potassium alcoholate and an electron donor system
Data Source
AI summary
The present invention relates to the industry of synthetic rubbers used in the production of tires, rubber products, in electrical and other fields, in particular, the invention relates to random copolymers of conjugated dienes and vinyl aromatic monomers, wherein the copolymer has a low content of vinyl groups, as well as to rubber mixtures based on these copolymers, and to a method for preparing said copolymers. The random copolymers with a low content of vinyl groups are prepared by copolymerization of conjugated dienes and vinyl aromatic monomers by using an organolithium initiator, wherein the copolymerization is carried out at a temperature of 70 to 130C in the presence of an electron donor system comprising a potassium alcoholate of the general formula ROK, wherein R is an aliphatic group comprising 5 to 15 carbon atoms, and an electron-donor (ED) additive, followed by modification with at least one compound selected from the group of cyclosiloxanes, oxocyclosiloxanes, lactams or vinyl pyridines. The technical result is the preparation of the random copolymers with a low content of vinyl groups which have excellent affinity to silica and carbon fillers, and the rubbers based on them having high elastic-hysteresis properties such as rolling resistance and wet grip.