Lubricant Composition Viscosity Index Improver Copolymer
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Solution Overview
Problem
Current lubricant compositions for vehicle transmissions exhibit insufficient shear stability and low-temperature characteristics, leading to viscosity reduction issues over long-term use and poor fuel economy due to inadequate viscosity index improvement.
Innovation Solution
A lubricant composition comprising a high-purity mineral base oil with a kinematic viscosity of 1.4 to 2.5 mm^2/s and a viscosity index improver containing a copolymer with specific alkyl (meth)acrylate monomers, such as 2-tetradecyloctadecyl (meth)acrylate, that maintains a high viscosity index and reduces viscosity reduction over time, while ensuring low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a lubricant with lower viscosity is used to reduce viscosity resistance and improve fuel economy, then fuel economy is improved, but oil leakage and seizure problems occur
Solution Approach 1:
The patent changes the chemical composition parameters of the viscosity index improver, specifically using a copolymer with methacrylic acid alkyl ester having C1-C4 linear alkyl group in controlled amounts (0.1-10 mass%) combined with other vinyl monomers. This compositional parameter change allows the lubricant to maintain lower base viscosity for fuel economy while the specific polymer structure provides sufficient viscosity stability to prevent oil leakage and seizure.
Solution Approach 2:
The patent creates a composite viscosity index improver system by combining multiple monomer types in specific ratios - methacrylic acid alkyl ester (C1-C4) at 0.1-10 mass%, and other vinyl monomers at 90-99.9 mass%. This composite polymer structure achieves both low-temperature fluidity (for fuel economy) and high-temperature viscosity maintenance (to prevent leakage and seizure).
2Use of energy by moving object
If a viscosity index improver is added to improve fuel economy through higher viscosity index, then fuel economy is improved, but shear stability after long hour drive becomes insufficient
Solution Approach 1:
The patent optimizes the molecular weight parameters and compositional ratios of the copolymer viscosity index improver. By controlling the methacrylic acid alkyl ester content at 0.1-10 mass% and adjusting the polymerization conditions to achieve specific molecular weights, the lubricant achieves high viscosity index for fuel economy while the optimized polymer structure resists shear degradation during long-term operation.
Solution Approach 2:
The patent uses a cost-effective copolymer composition with specific monomer ratios that provides adequate performance at reasonable cost. The methacrylic acid alkyl ester component (0.1-10 mass%) contributes to viscosity improvement while the majority composition (90-99.9% other vinyl monomers) ensures structural stability, creating an economical solution that maintains shear stability over extended service periods.
3Use of energy by moving object
If a viscosity index improver is added to improve fuel economy through higher viscosity index, then fuel economy is improved, but low-temperature characteristics at start-up become insufficient
Solution Approach 1:
The patent carefully controls the compositional parameters of the copolymer, specifically limiting methacrylic acid alkyl ester (C1-C4) to 0.1-10 mass% and using other vinyl monomers for the remaining 90-99.9 mass%. This parameter optimization ensures the lubricant maintains lower viscosity at cold start temperatures for adequate flow and lubrication, while still achieving high viscosity index at operating temperatures for fuel economy improvement.
Solution Approach 2:
The patent applies local quality by having different portions of the polymer structure serve different functions: the methacrylic acid alkyl ester segments (0.1-10 mass%) contribute to viscosity index improvement at high temperatures, while the other vinyl monomer segments (90-99.9 mass%) ensure low-temperature fluidity. This spatial/compositional differentiation allows simultaneous optimization of both fuel economy and cold-start performance.
Data Source
AI summary
The present invention provides a viscosity index improver having an excellent viscosity index improving effect, a lubricant composition having excellent low-temperature viscosity in which the viscosity reduction due to long-term use is small, and a method for producing the lubricant composition. A viscosity index improver of the present invention contains a copolymer (A) containing, as monomer units, an alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms, and an alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms, wherein the alkyl group of the alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms has a molar-average carbon number (Q) of 29 or more, and the alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms is contained as a monomer unit in an amount of 38 to 75% by weight based on the weight of the copolymer (A) .