Poly(meth)acrylate Viscosity Index Improver for Lubricants
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Solution Overview
Problem
Conventional poly(meth)acrylate-based viscosity index improvers for lubricating oils face challenges in achieving a balance between maintaining high shear viscosity at 150°C and lowering it at 100°C, while also providing sufficient fuel saving properties and shear stability, especially in internal combustion engines and transmission lubricating oils.
Innovation Solution
A poly(meth)acrylate-based viscosity index improver with a specific structure, comprising a core portion and three or more arm portions, where the polymer chain contains 15 to 45% of a methyl group and 10% or more of an alkyl group with 18 or more carbon atoms, and has a weight-average molecular weight of 100000 or more with a Mw/Mn ratio of 1.6 or less, is developed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional poly(meth)acrylate-based viscosity index improvers are used to increase viscosity index, then fuel saving property is improved, but high shear viscosity at 100°C cannot be lowered while maintaining high shear viscosity at 150°C
Solution Approach 1:
The viscosity index improver is segmented into a core portion and multiple arm portions (three or more), where each arm portion consists of a polymer chain with specific compositional ratios. This segmentation allows different parts of the molecule to contribute differently to viscosity at various temperatures, enabling simultaneous optimization of high shear viscosity at both 100°C and 150°C while maintaining fuel saving properties.
2Use of energy by moving object
If viscosity of lubricating oil for transmission is lowered to decrease viscosity resistance, then fuel saving property is improved, but oil leak and seizure problems arise
Solution Approach 1:
The invention changes the compositional parameters of the polymer chain, specifically controlling the ratio of structural units with different R2 groups (methyl group: 15-45 mass%, alkyl group with 18+ carbon atoms: 10 mass% or more). This parameter optimization allows the lubricating oil to achieve lower viscosity resistance for fuel saving while maintaining adequate viscosity at operating temperatures to prevent oil leak and seizure, thus improving both fuel efficiency and reliability.
3Use of energy by moving object
If conventional viscosity index improvers are used to improve viscosity index, then fuel saving property is improved, but shear stability is insufficient
Solution Approach 1:
The viscosity index improver is designed as a composite molecular structure combining a core portion with multiple arm portions, where each arm portion has a specific composition of structural units. This composite structure provides both the viscosity index improvement needed for fuel saving and the shear stability required for sustained performance, as the diverse structural units work together to maintain compositional stability under shear conditions.
Data Source
AI summary
The present invention provides a poly(meth)acrylate-based viscosity index improver comprising a core portion and three or more arm portions, wherein each of the arm portions consists of a polymer chain comprising a structural unit represented by the following formula (1), and one end of the polymer chain is bonded to the core portion, and wherein a weight-average molecular weight Mw is 100000 or more, and a ratio of the weight-average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, is 1.6 or less. [R1 represents hydrogen or a methyl group, and R2 represents a C1 to C36 alkyl group.]