Grease Composition with Semi-Crystalline Polyalphaolefin for Shear Stability
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Solution Overview
Problem
Existing lubricating greases suffer from low shear stability, leading to a decrease in consistency, lubricating film thickness, increased wear, and reduced service life, despite efforts to improve viscosity and maintain manufacturing processes.
Innovation Solution
A lubricating grease formulation comprising 50-95.8% base oil, 4-20% thickeners such as urea thickeners, metal complex soaps, and 0.2-40% semi-crystalline polyalphaolefin with 15-45% crystallinity, enhancing shear stability by structuring properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-viscosity base oil components are used to increase shear stability, then shear stability is improved, but base oil viscosity increases
Solution Approach 1:
The patent changes the chemical composition parameters of the base oil by incorporating specific ester components (dimer acid esters, trimellitic acid esters, hemimellitic acid esters, pyromellitic acid esters) with controlled viscosity ranges. This allows achieving high shear stability through molecular structure optimization rather than simply increasing overall viscosity, thus resolving the contradiction between shear stability and viscosity.
Solution Approach 2:
The patent creates a composite base oil system by combining multiple ester types (dimer acid esters, trimellitic acid esters, hemimellitic acid esters, pyromellitic acid esters) with specific additives. This composite approach provides synergistic effects where the combination delivers superior shear stability compared to individual components, without requiring excessive viscosity increase.
2Reliability
If modified manufacturing processes or special shear-stable thickener concepts are used to increase shear stability, then shear stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent specifies precise compositional parameters for the base oil (viscosity range 100-1000 mm²/s at 40°C, specific ester content ratios) and additive packages. By controlling these parameters within defined ranges, the patent achieves shear stability through formulation optimization rather than complex manufacturing processes, maintaining production simplicity while improving performance.
3Strength
If grease consistency is increased to improve load-bearing capacity, then load-bearing capacity is improved, but shear stability decreases
Solution Approach 1:
The patent optimizes the consistency range to 200-400 NLGI and carefully controls the thickener content (4-20% by weight). This balanced parameter selection ensures sufficient load-bearing capacity while preventing excessive consistency that would harm shear stability. The specific ester-based base oil composition further enhances this balance by providing film strength without compromising structural stability.
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 combination significantly improves shear stability, maintaining grease consistency and extending the service life of lubricated components.
Implementation Method 1
0.2-40% semi-crystalline polyalphaolefin with 15-45% crystallinity, enhancing shear stability by structuring properties
Data Source
Figure 1
AI summary
The invention relates to a lubricating grease containing a) 50 wt.% to 95.8 wt.%, based on the total weight of the lubricating grease, at least one base oil, b) 4 wt.% to 20 wt.%, based on the total weight of the lubricating grease, at least one thickening agent selected from urea thickeners, metal complex soaps, in particular lithium complex soaps, aluminum complex soaps, calcium complex soaps, metal simple soaps of the elements of the first main group of the periodic table, in particular lithium simple soaps and mixtures thereof, c) 0.2 wt.% to 40 wt.%%, based on the total weight of the lubricating grease, at least one semi-crystalline polyalphaolefin with at least one melting peak, measured according to DIN EN ISO 11357-3:2018 above 10°C and a degree of crystallinity of 15% to 45%, wherein the degree of crystallinity of the semi-crystalline polyalphaolefin is determined by determining the enthalpy of fusion of the semi-crystalline polyalphaolefin according to DIN EN ISO 11357-3:2018 and dividing by 2.93 J/g.