Grease Composition with Diurea Thickener for Shear Stability
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Solution Overview
Problem
Existing greases suffer from excessive softening due to shear stress, leading to issues like leakage, scattering, insufficient lubrication, and increased churning torque, which can cause damage to machine parts and overheating.
Innovation Solution
A grease composition using a mixture of diurea compounds with specific molecular ratios and a base oil, formulated to maintain a stable crystal structure through controlled heating and holding times, ensuring excellent shear stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If grease is subjected to strong shearing at the lubrication portion, then the fluidity of the grease bulk inside the bearing is improved, but the three-dimensional network structure of the thickener is destroyed and the grease softens excessively
Solution Approach 1:
The invention changes the chemical composition parameters of the thickener by using a specific mixture of diurea compounds with different alkyl chain lengths (C8, C10, C12, C14, C16, C18) in controlled ratios. This compositional parameter change allows the grease to achieve optimal balance between fluidity under shear and structural stability, preventing excessive softening while maintaining lubrication effectiveness.
Solution Approach 2:
The invention employs a composite thickener system consisting of multiple diurea compounds with different molecular structures and chain lengths. This composite approach creates a synergistic effect where the mixture of different diurea compounds forms a more stable three-dimensional network structure that resists shear-induced breakdown better than single-compound thickeners, thereby maintaining hardness while allowing necessary fluidity.
2Ease of operation
If the thickener network structure is destroyed by shear, then grease softening occurs, but this leads to leakage and scattering of grease
Solution Approach 1:
By adjusting the compositional parameters of the diurea thickener mixture and controlling the base oil content, the invention optimizes the grease consistency to achieve proper balance between flowability for distribution and retention for preventing leakage. The specific thickener composition allows the grease to flow when needed but maintain structural integrity to prevent excessive softening and leakage.
3Stability of the object's composition
If grease softens due to shear, then lubricant distribution becomes uneven, but this causes insufficient lubrication and part damage
Solution Approach 1:
The invention optimizes the chemical composition parameters of the thickener and base oil ratio to maintain grease consistency that ensures reliable lubrication. The specific diurea compound mixture creates a stable network structure that distributes lubricant evenly under shear conditions, preventing both excessive softening and insufficient lubrication, thereby ensuring continuous protective film formation on machine parts.
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 grease composition exhibits enhanced mechanical stability, reducing leakage and scattering, maintaining effective lubrication, and preventing overheating by retaining structural integrity under shear stress.
Implementation Method 1
the three-dimensional network structure of the thickener in the grease is destroyed and cannot return to its original hardness
Implementation Method 2
it begins to flow when a significant external force exceeding the yield value is applied, and when it begins to flow, it exhibits the same lubricating action as lubricating oil
Data Source
AI summary
A grease composition including(a) a thickener containing a mixture of the following formulas (I), (II), and (III):(I): R1-NHCONH—R2-NHCONH—R1,(II): R3-NHCONH—R2-NHCONH—R3, and(III): R1-NHCONH—R2-NHCONH—R3,where R1 is a cyclohexyl group, R2 is a C6-15 divalent aromatic hydrocarbon group, R3 is a C8-20 linear or branched alkyl group or alkenyl group, and {R1/(R1+R3)}×100 is 80 to 0 mol %, and(b) a base oil,wherein a 60-stroke worked penetration measured by a method specified in JIS K 2220.7 is 300 to 350, anda penetration in a roll stability test measured after applying shearing at 120° C. for 24 hours using a tester conforming to ASTM D 1831 is 440 or less.