Application of Self-Healing Materials to Tires

Structured review of Wizard-type additive incorporation into PU and rubber materials for AGV applications. Record examining mechanism, dispersion challenges, heat generation impact, probability of success, and prioritization.

https://www.yushiro.co.jp/products/wizard

1. What Wizard Plus Is Suitable For

■ Rubber Tires (NR / BR / SBR)

Primary Action

• Energy dissipation through reversible bonding
• Not a reinforcing filler
• Positioned as a crack growth suppression agent

Challenges

• Dispersion is the largest barrier
• Risk of increased heat generation
• Possible interference with curing systems

Probability of Success

• Moderate (application-limited)

■ PU (Polyurethane)

Compatibility with Material Characteristics

• Polar polymer
• Possesses a hydrogen-bond network
• Has a physically crosslinked structure

Evaluation

• Mechanistically highly compatible
• High probability of success

Implementation Method

• For cast PU, addition during polymerization is standard

2. Structuring for AGV Applications

AGVs are evaluated on different criteria than passenger vehicles.

Dominant Factors

• Low speed, high torque
• Pivot turning
• Micro-crack propagation
• Chipping

In other words, “failure mode” is more important than absolute wear volume.

Wizard-type additives act on this failure behavior.

3. AGV × PU Conclusion

■ Main Hardness Range

• Shore A 85–95
• Optimal zone: A 88–92

■ Expected Effects

• Reduction of chipping
• Improved fatigue life
• More uniform wear pattern
• Reduced dust generation
• Improved resistance to pivot turning

■ Addition Method

• Cast PU: addition during polymerization
• Recommended dosage: 0.5–1.5 wt%

→ Primary target application

4. AGV × Rubber Conclusion

■ Promising Rubbers

• ENR
• Low-AN NBR
• NR-dominant formulations (secondary option)

■ Expected Effects

• Reduced fatigue crack propagation
• Suppression of chunking wear
• Surface stabilization

■ Challenges

• Compatibility
• Dispersion
• Increased heat generation
• Cure interference

■ Addition Method

• Low-concentration masterbatch (recommended)
• Suggested range: 0.1 / 0.3 / 0.6 phr

→ Viable as a research theme

5. Decisive Differences Between PU and Rubber

6. Strategic Structuring

• For early implementation → PU AGV
• For material innovation theme → Rubber AGV
• Passenger vehicle application is currently irrational
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7. Current Rational Priority

1. Validate addition during polymerization in PU AGV tires
2. Validate micro-dosage addition in ENR / NBR-based rubber AGV
3. Consider CNF combination in the next phase