Hydrogenated Block Copolymer Viscosity Index Improver

The patent applies parameter changes by carefully controlling the hydrogenation degree of the polybutadiene blocks, maintaining it between 5-50% rather than complete hydrogenation. This partial hydrogenation approach modifies the physical and chemical parameters of the polymer to achieve a balance: sufficient thickening power is retained while crystallinity is suppressed, preventing solidification at low temperatures. The controlled hydrogenation level is a key parameter that resolves the contradiction between thickening effectiveness and low-temperature fluidity.

The invention uses composite materials by creating a block copolymer structure that combines different polymer blocks with distinct functions: polybutadiene blocks (partially hydrogenated) provide thickening characteristics, while polystyrene blocks provide structural framework and control viscosity. This composite block copolymer architecture allows each component to contribute its strengths while mitigating the weaknesses of individual materials, specifically preventing the solidification issue that plagues fully hydrogenated polymers.

The patent employs parameter changes by adjusting multiple critical parameters: the hydrogenation degree of polybutadiene blocks (5-50%), the molecular weight distribution of different blocks, and the overall copolymer composition. These parameter adjustments allow precise control over the polymer's behavior across different temperature ranges, enabling high viscosity index improvement while maintaining acceptable low-temperature pumping characteristics below specified limits.

The invention applies local quality by creating distinct functional regions within the block copolymer structure. The polybutadiene-rich blocks provide localized thickening power at operating temperatures, while the polystyrene blocks and partially hydrogenated regions provide localized flexibility and prevent excessive viscosity buildup at low temperatures. This spatial differentiation of functional properties within the polymer structure resolves the contradiction between high-temperature viscosity support and low-temperature pumpability.

The patent applies segmentation by dividing the polymer synthesis into distinct modular stages: first forming polystyrene blocks, then adding polybutadiene blocks with controlled hydrogenation, and finally assembling the complete block copolymer structure. This segmented approach allows each synthesis step to be optimized independently, using well-established polymerization techniques for each block type, thereby reducing overall manufacturing complexity and cost while maintaining high thickening power.

The invention uses parameter changes to simplify manufacturing by controlling the hydrogenation degree within an optimal range (5-50%) rather than requiring complete hydrogenation. This parameter optimization reduces the severity of the hydrogenation process, lowers energy consumption, and simplifies process control, all of which contribute to reduced production costs while preserving the necessary thickening characteristics.