Non-acidic Phosphorus Compounds in Lubricants
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Solution Overview
Problem
Lubricants containing dispersed alkali metal borates suffer from shortened shelf life due to the reaction of acidic phosphorus compounds with borate particles and basic additives, leading to precipitate formation and additive 'dropout', which negatively impacts load-carrying and seal-leak protection properties.
Innovation Solution
A lubricating composition comprising a mixture of hydrated alkali metal borate, dihydrocarbyl polysulfide, and non-acidic phosphorus compounds, including trihydrocarbyl phosphite and dihydrocarbyl dithiophosphate, with specific ratios of sulfides, combined with optional additives to enhance stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If acidic phosphorus compounds are used in the lubricant formulation, then load-carrying ability and seal-leak protection are improved, but shelf life is shortened due to precipitate formation
Solution Approach 1:
The patent changes the chemical parameter of the phosphorus compound from acidic to non-acidic form. This parameter change eliminates the harmful reaction with borate particles and basic additives that causes precipitate formation, thereby extending shelf life while maintaining load-carrying ability through alternative chemical mechanisms
Solution Approach 2:
The patent replaces the problematic acidic phosphorus compounds with non-acidic alternatives that do not form precipitates. This substitution allows the use of simpler, more stable chemical formulations that maintain performance without the shelf-life limitations of acidic compounds
2Stability of the object's composition
If more dispersant or detergent additives are added to improve shelf life, then storage stability is improved, but other performance properties of the gear lubricant are negatively impacted
Solution Approach 1:
The patent extracts and removes the problematic acidic phosphorus compounds from the formulation that cause precipitate formation. By eliminating the root cause of instability, the need for additional dispersants or detergents is reduced, maintaining performance properties without compromise
Solution Approach 2:
The patent changes the acidity parameter of the phosphorus compound to non-acidic, which fundamentally alters the chemical interactions in the formulation. This parameter change improves storage stability intrinsically without requiring additional additives that could negatively impact performance
3Temperature
If the storage temperature is increased, then the reaction rate of precipitate formation increases, but this accelerates additive dropout
Solution Approach 1:
The patent applies preliminary anti-action by using non-acidic phosphorus compounds that prevent the harmful chemical reaction from occurring in the first place. Since the problematic reaction pathway is eliminated, temperature-induced acceleration of precipitate formation and additive dropout is prevented
Solution Approach 2:
The patent changes the chemical parameter of the phosphorus compound to non-acidic form, which fundamentally alters the temperature dependence of the system. The new formulation shows reduced sensitivity to storage temperature increases, maintaining shelf life across a broader temperature range
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 superior load-carrying and seal-leak protection properties while significantly improving storage stability without sacrificing performance, as evidenced by extended sedimentation times and consistent extreme pressure performance across various temperatures.
Implementation Method 1
The acidic phosphorus compounds, those with a hydrogen attached directly to a phosphorus or attached to a heteroatom which is in turn attached to a phosphorus, which were previously relied on for other performance benefits, appear to react with either the borate particles or with the basic dispersant and detergent additives that are used to stabilize the borate particles and to form a precipitate
Implementation Method 2
a lubricating composition comprising an oil of lubricating viscosity having dispersed therein a minor amount of a mixture of: (a) a hydrated alkali metal borate component; (b) a dihydrocarbyl polysulfide component; and (c) a non-acidic phosphorus component
Implementation Method 3
the basic dispersant and detergent additives that are used to stabilize the borate particles
Data Source
AI summary
A lubricating composition with improved storage stability comprising a major amount of an oil of lubricating viscosity, at least one alkali metal borate, at least one polysulfide mixture having at least 40% dihydrocarbyl tetrasulfide or higher sulfides, and at least one non-acidic phosphorus compound comprised of a trihydrocarbyl phosphate and a dihydrocarbyl dithiophosphate derivative is disclosed. In addition to improved storage stability, the composition has improved wear performance when the ratio of polysulfides is controlled.