Recommended Silicone Selection for Silicone Blended with MTMS in Ceramic Coatings
Priority recommendation: hydroxyl-terminated modified polydimethylsiloxane (hydroxyl silicone oil); methyl hydrogen silicone oil as alternative option. The standard applicable viscosity ranges from 350 to 1000 cSt, with customized options of 100–350 cSt or 1000–5000 cSt for special formulation requirements.
1. Preferred Option: Hydroxyl-Functional Silicone Oil
- Advantages: Reactive hydroxyl groups (-OH) undergo crosslinking reaction with methoxy groups (-OCH₃) on MTMS to form stable covalent bonding network, preventing silicone migration, oil bleeding and deterioration against boiling water after long-term coating service.
- Application: High-temperature bake ceramic coatings (280~450°C curing), non-stick ceramic finishes requiring long-term weather resistance and chemical resistance, heat resistance up to 350~400°C with low yellowing and thermal degradation, improving coating leveling, surface slip and scratch resistance.
2. Alternative: Methyl Hydrogen Silicone Oil
- Advantages: Active Si-H bonds enable crosslinking with MTMS and other raw materials with catalyst addition to elevate coating crosslink density and thermal endurance.
- Application: Ceramic anti-fouling coating, hydrophobic ceramic topcoat and primer for enhanced substrate adhesion.
- Note: Strictly control hydrogen content to avoid undesirable side reactions with organic paint components.
3. Conventional Dimethyl Silicone Oil – Not Recommended for Regular Formulation
Non-functional conventional dimethyl silicone features no reactive groups to crosslink with MTMS, prone to migration and oil exudation under high temperature, resulting in poor durability of non-stick property and insufficient boiling resistance. Only acceptable for temporary surface treatment and low-grade non-high-temperature ceramic coatings.
Viscosity Selection Guide (25℃, Unit: cSt)
| Viscosity Range | Application Scenario | Core Property | Typical Dosage |
|---|---|---|---|
| 100~350 cSt | Leveling agent, defoamer, thin-film coating | Good fluidity and dispersion, moderate volatility | 0.5%~2.0% |
| 350~1000 cSt | General-purpose ceramic paint & non-stick coating | Balanced fluidity and film-forming performance, outstanding anti-blocking property | 1.0%~3.0% |
| 1000~5000 cSt | High-build coating, high-gloss & abrasion-resistant ceramic finish | Strong film-forming capacity, enhanced coating hardness and service life | 2.0%~5.0% |
Core selection note: 350~1000 cSt is the most widely adopted viscosity grade balancing workability and finished coating performance. Low-viscosity grade (<350 cSt) optimizes leveling yet compromises film thickness and durability; high-viscosity grade (>1000 cSt) strengthens coating integrity but demands thorough homogenization during MTMS blending.
Operational Guidelines & Precautions
- Mix Ratio: Silicone oil dosage accounts for 1%~5% of MTMS by mass, adjustable per finished coating specification.
- Crosslink Condition: Add organotin catalyst to accelerate condensation crosslink between hydroxyl silicone and MTMS.
- Construction: Homogenize fully under agitation prior to spray, brush or dip coating, cure following standard baking schedule of ceramic paint.
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Formulation Tuning:
- Blend partial phenyl-modified silicone for elevated thermal stability (heat resistance over 400℃);
- Supplement 0.5%~1.0% amino-modified silicone to boost substrate adhesion;
- Hydroxyl silicone is preferred for waterborne ceramic coatings instead of conventional dimethyl silicone.
Final Recommendation Summary
Select hydroxyl-terminated polydimethylsiloxane (hydroxyl silicone oil): 500 cSt for universal formulation, 1000 cSt for high-performance upgraded formula. Recommended addition dosage: 1.5%~3.0% against MTMS mass. Optimize finished coating durability with matched catalyst and specified curing baking process.
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