Comb Copolymer Viscosity Modifier for Lubricant Shear Stability
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Solution Overview
Problem
Conventional viscosity index improvers for lubricant oils face challenges in achieving optimal viscosity modification across a wide temperature range with minimal additive use and maintaining shear stability, often requiring high additive concentrations and compromising on low-temperature properties.
Innovation Solution
A comb copolymer viscosity modifier composed of hydrogenated polybutadiene-based (alk)acrylate ester macromonomers, C3-C8 alkyl (alk)acrylate ester monomers, and C12-C24 alkyl (alk)acrylate ester monomers, which are polymerized to create a polymer with specific weight percentages of each component, enhancing viscosity index and shear stability without premature polymer degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional viscosity index improvers are used to increase viscosity index, then viscosity modification is achieved, but shear stability deteriorates due to chain breakage under high shear
Solution Approach 1:
The patent applies segmentation by dividing the polymer structure into a backbone and multiple side chains (comb structure). This segmentation creates a configuration where the backbone provides shear stability while the side chains contribute to viscosity index, resolving the contradiction between viscosity improvement and shear stability maintenance.
Solution Approach 2:
The patent uses composite materials by combining different monomer units (styrene, butadiene, and alcohol-containing comonomers) to create a copolymer with integrated properties. The composite structure allows simultaneous achievement of high viscosity index and shear stability through the synergistic contribution of different polymer segments.
2Quantity of substance
If high additive concentrations are used to achieve optimal viscosity modification, then viscosity index improves, but low-temperature properties worsen
Solution Approach 1:
The patent applies parameter changes by incorporating comonomers with specific alcohol groups that modify the polymer's interaction with the base oil. This changes the physical-chemical parameters of the viscosity index improver, enabling effective viscosity modification at lower concentrations while preserving low-temperature fluidity and properties.
3Quantity of substance
If polymer molecular weight is increased to enhance viscosity, then viscosity index improves, but shear stability deteriorates due to chain breakage
Solution Approach 1:
The patent applies segmentation by creating a comb-like structure where the polymer chain is divided into a backbone and multiple attached side chains. This segmented architecture provides resistance to shear forces while maintaining high molecular weight, thereby improving viscosity index without sacrificing shear stability.
4Quantity of substance
If short-chain comonomer component is increased to raise viscosity index, then viscosity modification improves, but solubility at low temperatures deteriorates
Solution Approach 1:
The patent applies parameter changes by selecting comonomers with specific alcohol groups (such as fatty alcohols) that modify the polymer's solubility characteristics. This changes the chemical parameters of the copolymer, enabling it to maintain both high viscosity index and good solubility across a wide temperature range including low temperatures.
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 comb copolymer viscosity modifier effectively modifies lubricant oil viscosity across a wide temperature range, achieving high-temperature high-shear viscosities and kinematic viscosities while maintaining low-temperature properties with reduced additive usage, thus improving the overall performance and stability of lubricant compositions.
Implementation Method 1
The viscosities of polymer solutions in mineral oils or synthetic oils can be dependent upon the molecular weight, to some degree. This also may have the consequence that temperature dependence of the viscosity decreases or the VI increases with rising molecular weight
Implementation Method 2
In connection with the temperature increase, reference is also made to disentanglement of collapsed knots to give the extended worm-like molecule
Implementation Method 3
A comb copolymer viscosity modifier made by polymerization comprising at least, or consisting essentially of, the following monomers: (a) a hydrogenated polybutadiene-based (alk)acrylate ester macromonomer
Implementation Method 4
a hydrogenated polybutadiene-based (alk)acrylate ester macromonomer
Data Source
AI summary
A comb copolymer viscosity modifier may be made by polymerization comprising at least, or consisting essentially of, the following monomers: (a) a hydrogenated polybutadiene-based (alk)acrylate ester macromonomer (which repeat units may comprise from 7.0 wt % to 18 wt % of the repeat units of the comb copolymer viscosity modifier); (b) a C3-C8 alkyl (alk)acrylate ester monomer (which repeat units may comprise from 40 wt % to 71 wt % or from 45 wt % to 64 wt % of the repeat units of the comb copolymer viscosity modifier); and (c) a C12-C24 alkyl (alk)acrylate ester monomer, wherein repeat units based on the C12-C24 alkyl (alk)acrylate ester monomer comprise at least 21.0 wt % (and optionally up to 35.0 wt %) of repeat units of the comb copolymer viscosity modifier. Lubricant compositions comprising the comb copolymer viscosity modifier, as well as uses thereof and methods for modifying viscosity, are also contemplated herein.