EP Grease Additive Composition for Antiwear and Corrosion

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Solution Overview

Problem

Thiadiazole poly(ether)glycol complexes used in extreme pressure greases exhibit high surface affinity to metal surfaces, causing undesirable discoloration and interfering with antiwear additive effectiveness, while existing formulations with molybdenum compounds lack optimal performance in preventing wear and corrosion.

Innovation Solution

A lubricant composition comprising a thiadiazole poly(ether)glycol complex, molybdenum dihydrocarbyldithiophosphate, and zinc dihydrocarbyldithiophosphate, maintained in specific weight ratios, to provide exceptional antiwear and corrosion resistance without negative impacts on wear and corrosion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If thiadiazole poly(ether)glycol complexes are used as EP additives, then extreme pressure properties are improved, but copper discoloration and interference with antiwear additives occur

Engineering Contradiction:

Improveextreme pressure propertiesVSAvoidcopper discoloration and wear

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent introduces molybdenum dihydrocarbyldithiophosphate and zinc dihydrocarbyldithiophosphate as intermediary substances that mediate between the thiadiazole poly(ether)glycol complex and the metal surfaces. These intermediaries form protective films that prevent direct contact between the high-surface-affinity thiadiazole complex and the metal surfaces, thereby eliminating copper discoloration while maintaining extreme pressure protection.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical composition parameters by introducing specific ratios of molybdenum (77-450 ppm) and zinc (600-1000 ppm) dihydrocarbyldithiophosphates alongside the thiadiazole poly(ether)glycol complex. This parameter modification alters the surface interaction characteristics, reducing the harmful surface affinity effects while preserving the extreme pressure benefits.

Inventive Principle:

Principle #35Parameter changes

2Strength

If high surface affinity additives are used to improve extreme pressure properties, then antiwear effectiveness is reduced due to coating formation

Engineering Contradiction:

Improveextreme pressure propertiesVSAvoidantiwear effectiveness

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

Molybdenum and zinc dihydrocarbyldithiophosphates serve as intermediary substances that form protective films on metal surfaces first, creating a barrier that prevents thiadiazole poly(ether)glycol complex from forming interfering coatings. This intermediary action ensures that antiwear additives can function effectively while extreme pressure properties are maintained.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite additive system combining thiadiazole poly(ether)glycol complex with molybdenum and zinc dihydrocarbyldithiophosphates in specific ratios. This composite formulation synergistically combines the extreme pressure benefits of thiadiazoles with the antiwear capabilities of molybdenum and zinc compounds, achieving both functions simultaneously.

Inventive Principle:

Principle #40Composite materials

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 composition achieves excellent Timken OK loads, acceptable wear scars, and minimal copper corrosion, demonstrating superior extreme pressure and antiwear properties compared to alternative additives and formulations.

Implementation Method 1

Thiadiazoles are compounds that are effective EP additives... their high surface affinity to metals surfaces produces coatings

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

EP greases lubricate under highly loaded conditions and require highly effective EP additives to prevent scoring and welding

Methodology Applied

Scientific EffectBoundary lubrication: Lubrication

Data Source

PatentEP2231681B1Additive composition for EP greases with excellent antiwear and corrosion properties

Publication Date: 2013.11.06 VANDERBILT CHEMICALS LLC

AI summary

A lubricant composition is provided as follows: At least 90% of a base grease; (a) a thiadiazole poly(ether)glycol complex in an amount which provides about 1500 to 3500 ppm sulfur; (b) molybdenum dihydrocarbyldithiophosphate in amount which provides about 77 to 450 ppm molybdenum; and (c) zinc dihydrocarbyldithiophosphate in an amount which provides about 600 to 1000 ppm zinc. An additive composition for grease, consisting of components (a), (b) and (c), is also provided.