Syndiotactic Copolymer Viscosity Modifiers for Lubricating Oil

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Solution Overview

Problem

Existing viscosity index improvers based on propylene-based ethylene-propylene copolymers face a trade-off between thickening efficiency and low-temperature performance, with higher ethylene content improving TE but leading to crystallinity and gelation issues.

Innovation Solution

Development of syndiotactic propylene-based ethylene-propylene copolymers with specific ethylene and propylene content ratios and molecular weights, optimized for improved viscometrics and low-temperature performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If higher ethylene content is used in propylene-based ethylene-propylene copolymers, then thickening efficiency is improved, but crystallinity increases leading to gelation and poor low-temperature performance

Engineering Contradiction:

Improvethickening efficiencyVSAvoidlow-temperature performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the ethylene content within 2-20 wt% range and propylene content within 80-98 wt% range, along with controlling molecular weight (Mw) between 10-250 kg/mol and rr triad tacticity between 50-99%. These parameter optimizations enable the copolymer to achieve adequate thickening efficiency while preventing crystallinity and gelation, thereby maintaining good low-temperature performance.

Inventive Principle:

Principle #35Parameter changes

2Strength

If higher ethylene content is used to increase thickening power, then viscous properties are improved, but the polymer exhibits melting point and non-uniform appearance

Engineering Contradiction:

Improvethickening powerVSAvoiduniformity and solubility

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The patent resolves this contradiction by optimizing the ethylene content to 2-20 wt% (avoiding higher ethylene content that causes crystallinity) and controlling molecular weight parameters (Mw: 10-250 kg/mol). This parameter optimization ensures the copolymer maintains adequate thickening power while preventing phase separation, melting points, and non-uniform appearance in the lubricating oil composition.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If propylene-based copolymers with low ethylene content are used, then low-temperature performance is improved, but thickening efficiency decreases

Engineering Contradiction:

Improvelow-temperature performanceVSAvoidthickening efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent creates an optimized composite copolymer system combining propylene (80-98 wt%), ethylene (2-20 wt%), and controlling rr triad tacticity (50-99%). This composite structure with specific composition ratios and molecular weight parameters enables the material to simultaneously achieve good low-temperature performance and adequate thickening efficiency, overcoming the limitations of using low ethylene content alone.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP4426803B1Lubricating oil composition with viscosity modifier based on syndiotactic propylene-based ethylene-propylene copolymers with improved properties

Publication Date: 2025.09.10 CHEVRON ORONITE CO LLC

AI summary

Provided is a lubricating oil composition that includes a major amount of a lubricant base oil and a minor amount of a viscosity index improver comprising a syndiotactic propylene-based ethylene-propylene copolymer comprising: a) 2 to 20 % by weight of ethylene, b) 80 to 98 % by weight of propylene; c) 50 to 99% of rr triads; and d) Mw (LS) of 10 to 250 kg/mol.