Lubricant Oil Composition with High Molecular Weight Viscosity Index Improver
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Solution Overview
Problem
Conventional lubricating oils face challenges in achieving adequate fuel efficiency while maintaining lubricating performance under severe conditions, as reducing kinematic viscosity to improve fuel efficiency can lead to reduced lubricating performance and durability issues.
Innovation Solution
A lubricating oil composition with a specific combination of base oil and viscosity index improver, characterized by a kinematic viscosity at 100° C. of 1-10 mm2/s, a % Cp of 70 or greater, and a % CA of no greater than 2, along with a viscosity index improver with a weight-average molecular weight of 100,000 or greater, to achieve a high HTHS viscosity at 150° C. and low kinematic viscosity at 40° C. and 100° C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the kinematic viscosity of the lubricating oil is reduced to improve fuel efficiency, then fuel efficiency is improved, but the lubricating performance under severe conditions deteriorates
Solution Approach 1:
The invention changes the molecular weight parameter of the viscosity index improver to 100,000 or greater, which fundamentally alters the viscosity-temperature relationship. This parameter change enables the oil to maintain high viscosity at elevated temperatures (preserving lubricating performance) while having lower viscosity at operating temperatures (improving fuel efficiency).
Solution Approach 2:
The invention uses a composite approach by combining a base oil with specific viscosity index improvers having controlled molecular weights and PSSI values. This composite formulation creates a lubricating oil that exhibits dual characteristics: low kinematic viscosity for fuel efficiency and high HTHS viscosity for reliable lubrication under severe conditions.
2Reliability
If the HTHS viscosity at 150° C. is raised and kinematic viscosity at 40° C. is lowered to prevent wear and improve fuel efficiency, then fuel efficiency and durability are improved, but it becomes extremely difficult to satisfy all viscosity conditions with conventional lubricating oils
Solution Approach 1:
The invention introduces a specific parameter threshold for viscosity index improvers (molecular weight ≥100,000 and MW/PSSI ratio ≥1.0×10^4) that simplifies the formulation process. By focusing on these key parameters, the invention achieves multiple viscosity requirements simultaneously without requiring complex multi-component formulations.
Solution Approach 2:
The invention applies different quality requirements to different aspects of the viscosity index improver: high molecular weight for maintaining HTHS viscosity, and controlled PSSI for achieving appropriate kinematic viscosity. This localized quality approach allows satisfaction of multiple contradictory viscosity specifications through a single improver type.
Data Source
AI summary
The invention provides a lubricating oil composition comprising a lubricating base oil with a kinematic viscosity at 100° C. of 1-10 mm2/s, a % Cp; of 70 or greater and a % CA of no greater than 2 and a viscosity index improver having a weight-average molecular weight of 100,000 or greater and a ratio of weight-average molecular weight to PSSI of 1.0×104 or greater, at 0.1-50% by mass based on the total amount of the composition, and having a kinematic viscosity at 100° C. of 9.0-12.5 mm2/s and a HTHS viscosity at 150° C. of 2.8 mPa·s or greater. It further provides a lubricating oil composition comprising a lubricating base oil with a kinematic viscosity at 100° C. of 1-6 mm2/s, a % Cp of 70 or greater and a % CA of no greater than 2, a hydrocarbon-based viscosity index improver with a PSSI of no greater than 20, and a poly(meth)acrylate-based viscosity index improver.