Block Copolymer Viscosity Control for Asphalt Fine Particle Dispersion
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Solution Overview
Problem
Existing asphalt compositions struggle to effectively disperse and agglomerate fine particles in reused aggregates, leading to reduced strength and increased energy consumption in production, as seen in Japanese Patents 9-12898 and 2004-59781.
Innovation Solution
A block copolymer with specific viscosity, magnesium, and calcium content, comprising a polymer block mainly composed of vinyl aromatic and conjugated diene monomer units, is used to enhance the dispersibility of fine particles in asphalt compositions, improving the strength and production efficiency of modified asphalt mixtures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional block copolymers are used in asphalt compositions, then the basic asphalt properties are maintained, but the dispersibility of fine particles in reused aggregates is insufficient and production energy consumption increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the viscosity of the block copolymer (5-45 mPa·s at 25°C in toluene), magnesium content (1-200 ppm), and calcium content (100-500 ppm). These parameter optimizations enable the copolymer to effectively disperse fine particles in reused aggregates, improving asphalt mixture strength while reducing production energy consumption
Solution Approach 2:
The patent uses a composite block copolymer structure combining polymer block (A) mainly composed of vinyl aromatic monomer units and polymer block (B) mainly composed of conjugated diene monomer units. This composite structure provides both compatibility with asphalt and effective fine particle dispersion, resolving the contradiction between maintaining asphalt properties and improving dispersibility
2Productivity
If block copolymer with high dissolution rate is used, then energy consumption during production is reduced, but the dispersibility and agglomeration control of fine particles is insufficient
Solution Approach 1:
The patent optimizes the viscosity parameter to 5-45 mPa·s at 25°C, which balances dissolution rate and dispersibility. This viscosity range ensures rapid dissolution in asphalt while maintaining sufficient dispersing power for fine particles, achieving both high productivity and composition stability
3Quantity of substance
If reused aggregates with fine particles are used, then material utilization is improved, but the dispersibility of fine particles deteriorates leading to reduced asphalt mixture strength
Solution Approach 1:
The block copolymer acts as an intermediary substance between asphalt and fine particles in reused aggregates. The copolymer's specific viscosity and metal element content enable it to adsorb onto fine particle surfaces while maintaining compatibility with asphalt, achieving effective dispersion and restoring asphalt mixture strength
Solution Approach 2:
The patent introduces magnesium (1-200 ppm) and calcium (100-500 ppm) elements in the block copolymer, which enhance the interaction with fine particles. These parameter changes improve the copolymer's ability to disperse fine particles in reused aggregates, maintaining high material utilization while achieving required strength
Data Source
AI summary
[Technical Problem] An object of the present invention is to provide a block copolymer that, when added to an asphalt, can improve the dispersibility of a fine particle in an asphalt composition containing a fine particle aggregate, thereby improving the strength of a modified asphalt mixture. [Solution to Problem] Provided is a block copolymer that can yield an asphalt composition having good dispersibility of a fine particle aggregate and yield a modified asphalt mixture having excellent strength. A block copolymer (P) comprising a polymer block (A) mainly composed of a vinyl aromatic monomer unit and a polymer block (B) mainly composed of a conjugated diene monomer unit, the block copolymer (P) satisfying the following <condition (1)> to <condition (3)>: <Condition (1)> a 5% by mass toluene solution viscosity at 25°C is 5 mPa·s or more and 45 mPa·s or less; <Condition (2)> a content of a magnesium element is 1 to 200 ppm; <Condition (3)> a content of a calcium element is 100 to 500 ppm.