Viscosity Index Improver Solubility Parameter Control
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Solution Overview
Problem
Existing viscosity index improvers for engine oils are insufficient in reducing high-temperature high-shear viscosity at 80° C. while maintaining startability in cold temperatures, leading to issues like oil leakage and seizure.
Innovation Solution
A viscosity index improver comprising a (co)polymer with a polyolefin-based monomer and a base oil, where the absolute difference in solubility parameter between the polymer and the base oil is 0.8 to 2.0 (cal/cm3)1/2, providing excellent shear stability and a high viscosity index.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the viscosity of engine oil is lowered to reduce fuel consumption, then the HTHS viscosity at effective temperature is reduced, but oil leakage and seizure occur
Solution Approach 1:
The invention changes the chemical structure parameters of the viscosity index improver by specifying a solubility parameter difference between 0.8-2.0 (cal/cm³)¹/², which fundamentally alters how the additive interacts with the base oil across different temperatures, enabling simultaneous achievement of low HTHS viscosity and adequate film strength
Solution Approach 2:
The invention creates a composite lubricating oil system by carefully selecting the combination of base oil and viscosity index improver with specific solubility parameter relationships, resulting in a synergistic effect where the composite formulation achieves properties that neither component alone could provide
2Use of energy by moving object
If known viscosity index improvers are added to reduce HTHS viscosity, then the viscosity at effective temperature is reduced, but shear stability is insufficient
Solution Approach 1:
The invention identifies and controls the solubility parameter difference as the critical parameter governing shear stability, setting it within the specific range of 0.8-2.0 (cal/cm³)¹/² to optimize the balance between viscosity reduction and compositional stability under shear conditions
3Ease of operation
If viscosity is reduced for better cold startability, then low temperature viscosity is improved, but HTHS viscosity at effective temperature increases
Solution Approach 1:
The invention applies local quality by designing a viscosity index improver with specific solubility characteristics that selectively affect viscosity at different temperature ranges, providing different functional properties (low temperature flow vs. high temperature film strength) through a single additive component
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 achieves excellent shear stability, low high-temperature high-shear viscosity, and high viscosity index, ensuring effective engine oil performance across varying temperatures.
Implementation Method 1
the absolute value of difference in solubility parameter between the (co)polymer (A) and the base oil is 0.8 to 2.0 (cal/cm3)1/2
Data Source
AI summary
The present invention aims to provide a viscosity index improver excellent in shear stability and having a low HTHS viscosity and a high viscosity index. The viscosity index improver of the present invention contains a (co)polymer (A) containing a polyolefin-based monomer as an essential monomer unit, and a base oil, wherein the absolute value of difference in solubility parameter between the (co)polymer (A) and the base oil is 0.8 to 2.0 (cal/cm3)1/2.