Lubricant Composition with Dual Viscosity Index Improvers
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Solution Overview
Problem
Conventional lubricating base oils and viscosity index improvers fail to achieve optimal fuel efficiency and low-temperature viscosity characteristics, leading to issues such as wear and seizing under high-temperature, high-shear conditions, and increase production costs due to the need for expensive synthetic oils.
Innovation Solution
A lubricating oil composition comprising a lubricating base oil with specific kinematic viscosity and viscosity index, combined with first and second viscosity index improvers, and a friction modifier, which maintains high-temperature high-shear viscosity while reducing kinematic viscosities at lower temperatures without using synthetic or low-viscosity mineral oils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional lubricating base oils and viscosity index improvers are used to reduce kinematic viscosity and increase viscosity index for fuel efficiency, then fuel efficiency improves, but lubricating performance under severe conditions deteriorates leading to wear and seizing
Solution Approach 1:
The invention changes the chemical composition parameters of the viscosity index improver by specifying a polymethacrylate structure with particular molecular weight (10,000-100,000) and methacrylate unit content (80-99 mol%). This specific parameter range achieves optimal balance between viscosity index improvement and high-temperature viscosity maintenance, resolving the contradiction between fuel efficiency and lubricating performance
Solution Approach 2:
The invention uses a composite approach by combining specific base oils (group II or group III with viscosity index 80-120 and kinematic viscosity at 100°C of 2.0-10.0 mm²/s) with the specially formulated polymethacrylate viscosity index improver. This composite material system achieves synergistic effect where the base oil provides foundational lubrication and the polymethacrylate enhances viscosity index while maintaining high-temperature film strength
2Ease of operation
If synthetic oils such as poly-α-olefin base oils or ester base oils are used to achieve excellent low-temperature viscosity characteristics, then low-temperature performance improves, but production cost increases
Solution Approach 1:
The invention replaces expensive synthetic base oils with cheaper conventional base oils (group II or group III mineral oils) that have shorter service life characteristics but can be effectively extended through the addition of polymethacrylate viscosity index improver. This substitution achieves similar low-temperature performance at lower cost by using a cost-effective base oil combined with a targeted additive approach
3Loss of energy
If low-viscosity mineral oil base oils are used to reduce product viscosity, then kinematic viscosity decreases improving fuel efficiency, but viscosity index decreases and NOACK evaporation increases
Solution Approach 1:
The polymethacrylate viscosity index improver acts as an intermediary substance that mediates between the low-viscosity base oil and the required performance specifications. It absorbs the negative effects of low base oil viscosity by providing viscosity index enhancement and evaporation control, allowing the use of low-viscosity group II or group III base oils while maintaining compositional stability
Data Source
AI summary
The invention provides a lubricating oil composition comprising:a lubricating base oil having a kinematic viscosity at 100° C. of 1-10 mm2/s, a % Cp of 70 or greater and a % CA of not greater than 2;a first viscosity index improver of 0.01-10% by mass, based on the total weight of the composition, wherein the first viscosity index improver is a poly(meth)acrylate having a weight-average molecular weight of not greater than 100,000; anda second viscosity index improver of 0.01-50% by mass, based on the total weight of the composition, wherein the second viscosity index improver is a polymer having a weight-average molecular weight of 100,000 or greater and containing a structural unit represented by the following formula (1) in a proportion of 0.5-70 mol %,the composition having a kinematic viscosity at 100° C. of 4-12 mm2/s and a viscosity index of 140-300.wherein R1 represents hydrogen or a methyl group and R2 represents a C16 or greater straight-chain or branched hydrocarbon, or an oxygen- and/or nitrogen-containing C16 or greater straight-chain or branched organic group.