Polyalkyl(meth)acrylate Comb Polymers for Engine Oil Viscosity
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Solution Overview
Problem
Current viscosity index improvers for lubricant oils face challenges in achieving high thickening efficiency and high-temperature high-shear stability while maintaining low treat rates, leading to increased costs and deposit formation issues in engine oils.
Innovation Solution
Development of polyalkyl(meth)acrylate based comb polymers with weight-average molecular weights of 700,000 g/mol or greater and number-average molecular weights of 130,000 g/mol or greater, characterized by a specific molecular weight ratio that enhances thickening efficiency and high-temperature high-shear performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the thickening efficiency of a VI improver is increased, then the kinematic viscosity at 100°C improves, but the high-temperature high-shear viscosity increases which leads to reduced fuel economy
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight distribution parameters (Mw and Mn) of the comb polymer to achieve the desired balance between thickening efficiency and fuel economy. The specific parameter ranges (Mw ≥ 700,000 g/mol and Mn ≥ 130,000 g/mol) are optimized to provide high KV100 improvement while maintaining low HTHS100 values
Solution Approach 2:
The invention uses a composite molecular structure combining a polybutadiene backbone with polyalkyl(meth)acrylate side chains to create a comb polymer architecture. This composite structure provides both the thickening efficiency needed for high KV100 and the low shear sensitivity required for good fuel economy performance
2Quantity of substance
If the treat rate of VI improver is reduced to lower costs, then the amount of additive decreases, but achieving sufficient thickening efficiency becomes more difficult
Solution Approach 1:
The patent changes the molecular weight parameters of the polymer to achieve higher thickening efficiency per unit mass. By setting Mw ≥ 700,000 g/mol and Mn ≥ 130,000 g/mol, the polymer provides superior thickening efficiency that allows reduction of treat rate while maintaining adequate KV100 improvement
3Ease of manufacture
If conventional VI improvers are used to improve kinematic viscosity, then thickening efficiency is achieved, but deposit formation increases in engine oils
Solution Approach 1:
The comb polymer structure with polybutadiene backbone and polyalkyl(meth)acrylate side chains provides a composite material that delivers effective thickening while the specific molecular architecture reduces deposit formation compared to conventional linear polymers
Solution Approach 2:
By optimizing the molecular weight distribution parameters (Mw and Mn) within specific ranges, the patent achieves thickening efficiency while the controlled polymer structure minimizes deposit formation tendencies
Data Source
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AI summary
The present invention is directed to polyalkyl(meth)acrylate based comb polymers with weight-average molecular weights of 700.000 g/mol or greater and number-average molecular weights of 130.000 g/mol or greater, their preparation, lubricant compositions comprising such comb polymers and their use to improve the high temperature-high shear performance of lubricant compositions, especially of engine oil (EO) compositions.