Sulfurized Polyolefin Oligomer Copper Corrosion
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Solution Overview
Problem
Sulfurized isobutylene oligomers used in lubricants provide effective extreme pressure performance but are detrimental to copper and copper alloys, causing unacceptable corrosion, and are insoluble in certain base oils like API Group IV polyalphaolefin (PAO) oils, limiting their application.
Innovation Solution
A sulfurized polyolefin oligomer is synthesized through a three-step process involving reacting a C2 to C18 olefin with a sulfur halide, followed by reaction with an alkali metal hydrosulfide and alkali metal hydroxide in an aqueous solution, and then treated with an aqueous alkaline solution to form a sulfurized polyolefin oligomer with improved solubility and reduced copper corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If sulfurized isobutylene oligomers are used as extreme pressure additives, then extreme pressure performance is improved, but copper corrosion increases
Solution Approach 1:
The patent modifies the chemical structure of sulfurized isobutylene oligomers by controlling the sulfur content to be between 30-50 weight percent and adjusting the molecular weight to be between 300-800. These parameter changes reduce the corrosiveness to copper while preserving extreme pressure performance. The specific sulfur content range optimizes the balance between protective film formation and corrosion inhibition.
2Strength
If sulfurized isobutylene oligomers are used, then extreme pressure performance is improved, but solubility in API Group IV base oils deteriorates
Solution Approach 1:
The patent controls the molecular weight of the sulfurized polyolefin oligomer to be between 300-800, which optimizes solubility in API Group IV polyalphaolefin base oils. This molecular weight range prevents excessive viscosity and ensures complete dissolution while maintaining the extreme pressure protective properties of the sulfurized additive.
3Strength
If traditional sulfurized additives are used, then copper corrosion protection is poor, but extreme pressure performance is good
Solution Approach 1:
The patent creates a composite chemical structure combining sulfurized polyolefin oligomers with specific molecular weight and sulfur content characteristics. This composite approach integrates multiple functional properties: extreme pressure protection through sulfur content, corrosion inhibition through molecular structure optimization, and solubility through controlled oligomer size, achieving a multi-functional additive system.
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 resulting sulfurized polyolefin oligomer exhibits low copper corrosion and solubility in both API Group III and Group IV base oils, enhancing its suitability for use in gear oils and other lubricating compositions while maintaining extreme pressure performance.
Implementation Method 1
a copper coupon immersed in the sulfurized polyolefin oligomer for about 180 minutes at about 121°C pursuant to ASTM D130 exhibits about 15 mg or less of copper weight loss
Implementation Method 2
reacting the intermediate sulfurized olefin reaction product with an alkali metal hydrosulfide, an alkali metal hydroxide, and sulfur in an aqueous solution to form a sulfurized polyolefin reaction product; and (c) treating the sulfurized polyolefin reaction product with an aqueous alkaline solution
Data Source
Figure 1~2
AI summary
A sulfurized extreme pressure additive and lubricant including the same providing good copper corrosion and seal compatibility.