PAO Base Stock Composition for Low-Viscosity Engine Oil Blending

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Solution Overview

Problem

Existing low-viscosity Group IV PAO base stocks used in high-quality engine oils require lower viscosity, higher viscosity index, and lower Noack volatility, along with improved blending properties to meet the demands of modern automotive engines.

Innovation Solution

The use of oligomers of linear C14 and C16 mono-olefins, produced through oligomerization with a Lewis acid catalyst system, including BF3 and ethanol/ethyl acetate, to create a base stock comprising predominantly dimers and optionally trimers, which are branched and have specific branch connectivity, resulting in high viscosity index, low viscosity, and low pour point.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional low-viscosity Group IV PAO base stocks are used, then good performance is achieved, but viscosity index is insufficient and Noack volatility is too high

Engineering Contradiction:
ImproveperformanceVSAvoidviscosity index
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent changes the molecular parameters of the base stock by using C14 and C16 alpha-olefin monomers with specific carbon chain lengths to produce dimers and trimers with optimized molecular weights and structures, achieving higher viscosity index and lower Noack volatility while maintaining good performance

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite base stock composition by blending dimers (60-80 wt%) and trimers (20-40 wt%) of specific carbon chain lengths, combining the advantages of both oligomer types to achieve superior viscosity index and volatility characteristics that neither component alone can provide

Inventive Principle:
Principle #40Composite materials

2Quantity of substance

If base stocks with lower viscosity are formulated, then KV100 requirement is met, but pour point increases

Engineering Contradiction:
ImproveviscosityVSAvoidpour point
Core Design Contradiction:
Quantity of substanceVSTemperature

Solution Approach 1:

The patent applies local quality by creating a specific molecular structure distribution within the base stock, where dimers and trimers with controlled branching ratios (0.15-0.35) are used to optimize local molecular packing and intermolecular forces, achieving low pour point while maintaining low viscosity

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the structural parameters of the base stock molecules by controlling the branching ratio and molecular weight distribution of dimer and trimer components, creating an optimal balance between viscosity and pour point characteristics

Inventive Principle:
Principle #35Parameter changes

3Quantity of substance

If highly branched oligomers are used to reduce viscosity, then KV100 is reduced, but blending performance deteriorates

Engineering Contradiction:
ImproveviscosityVSAvoidblending performance
Core Design Contradiction:
Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The patent optimizes the branching ratio parameter to a specific range (0.15-0.35) that balances molecular compactness for low viscosity with structural regularity for good blending performance, avoiding both excessive linearity and excessive branching

Inventive Principle:
Principle #35Parameter changes

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 base stock exhibits improved viscosity index, low Noack volatility, and high pour point, enabling it to blend effectively with conventional PAO base stocks to form high-quality, low-viscosity engine oils, particularly in 0W grades, while maintaining desirable lubricant properties.

Implementation Method 1

produced through oligomerization with a Lewis acid catalyst system, including BF3 and ethanol/ethyl acetate

Methodology Applied
Scientific EffectCatalysis: Catalysis

Data Source

PatentEP3856879B1Base stocks and oil compositions containing the same
Publication Date: 2026.03.25 EXXONMOBIL CHEMICAL PATENTS INC
  • EP3856879B1 patent drawingFigure 1~2
  • EP3856879B1 patent drawingFigure 3~4
  • EP3856879B1 patent drawingFigure 5~6

AI summary

This disclosure relates to base stocks comprising a C28-C32 hydrocarbon fraction and optionally a C42-C48 hydrocarbon fraction produced by dimerization and trimerization of a linear C14 mono-olefin, a linear C16 mono-olefin, or a mixture thereof, in the presence of a Lewis acid, oil compositions comprising such base stock(s), and processes for making such base stocks.