Introduction
This category of products mainly consists of methanol and hydroxymethyl melamine reacting in different molar ratios to form highly methylated, partially methylated, and highly imido methylated melamine resin products. This series of products can react with functional polymers with hydroxyl, carboxyl, and amide groups to produce flexible, scratch resistant, and adhesive products, which are widely used in coating systems based on acrylic acid, polyester, alkyd, epoxy resin, and polyurethane.
| High solid methyl etherified melamine resin products |
| MT 300 | White waxy solid | ≥98 | – | ≤0.1 | – | Fully methylated hexahydroxymethyl melamine resin |
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| MT 303 | Colorless viscous liquid | ≥98 | 2000-6000 | ≤0.3 | – | Highly methylated hexahydroxymethyl melamine resin |
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| MT 303lf | Colorless viscous liquid | ≥98 | 2000-6000 | ≤0.1 | – | low free formaldehyde303 |
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| MT 303w | Colorless viscous liquid | ≥96 | 2000-6000 | ≤0.5 | – | 303 |
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| High iminomethylated dense amine resin |
| MT 325 | Colorless viscous liquid | 78-82 | 2500-4500 | ≤0.75 |
| Fast curing, no need for strong acid catalysis, low formaldehyde emission |
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| MT 327 | Colorless viscous liquid | 88-92 | 5100-16000 | ≤0.8 |
| Fast curing, no need for strong acid catalysis, low formaldehyde emission |
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| MT 385 | Colorless viscous liquid | 76-81 | 1000-1600 | ≤0.4 |
| Fast curing, no need for strong acid catalysis, low formaldehyde emission |
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| Part of the methylated melamine resin |
| MT 370 | Colorless viscous liquid | 86-90 | 5100-10200 | ≤3.5 |
| No need for curing, no need for strong acid catalysis |
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| MT 380 | Colorless viscous liquid | 76-82 | 1200-3500 | ≤2.5 |
| No need for curing, no need for strong acid catalysis |
Methylated Melamine Resins: Technical Overview
| Category | Specifications |
| Definition | Thermosetting amino resins formed by reacting melamine with formaldehyde and methanol, used as crosslinkers in coatings and adhesives |
| Chemical Structure | Polymeric methylol melamine ethers |
Types of Methylated Melamine Resins
| Type | Methylation Degree | Solubility | Curing Conditions |
| Partially Methylated | 50-70% methyl groups | Water-soluble | Acid catalyst, 120-150°C |
| Fully Methylated | >90% methyl groups | Organic solvent-soluble | Self-crosslinking, 140-180°C |
| High-Imino | Low methylation, high NH groups | Water/organic soluble | Low-temperature cure (100-130°C) |
Key Properties & Performance
| Property | Typical Value | Test Method |
| Non-Volatile Content | 80-100% | ISO 3251 |
| Viscosity (25°C) | 500-3000 mPa·s | ISO 3219 |
| Free Formaldehyde | <1% | DIN EN ISO 9397 |
| Gel Time (150°C) | 3-10 minutes | ASTM D2471 |
Comparison with Other Amino Resins
| Parameter | Methylated Melamine | Urea-Formaldehyde | Benzoguanamine |
| Weather Resistance | Excellent | Poor | Good |
| Chemical Resistance | High (acids, alkalis) | Moderate | Moderate |
| Flexibility | Moderate | Brittle | Good |
| Cost | High | Low | Very High |
Formulation Guidelines
| Component | Role | Typical Loading (wt%) |
| Melamine Resin | Crosslinker | 10-30% (on resin solids) |
| Hydroxyl Polymer (e.g., polyester, acrylic) | Main resin | 70-90% |
| Acid Catalyst (e.g., p-TSA) | Cure accelerator | 0.1-1.0% |
| Flow Additives | Surface leveling | 0.5-2.0% |
Industrial Applications
| Industry | Use Case | Resin Type Preferred |
| Automotive | Clearcoats, basecoats | Fully methylated, high-gloss |
| Coil Coatings | Pre-painted metal | Partially methylated, flexible |
| Wood Coatings | Furniture lacquers | High-imino, fast-cure |
| Can Coatings | Food-contact linings | Fully methylated, FDA-compliant |
Curing Mechanism & Conditions
| Stage | Process | Temperature/Time |
| Methylol Condensation | Ether crosslinking | 100-140°C, 10-30 min |
| Self-Crosslinking | Residual –CH₂OH groups react | >150°C, 5-15 min |
| Post-Cure | Full network formation | 24h at ambient |
Advantages & Limitations
| Advantage | Technical Benefit | Limitation | Challenge |
| High hardness | Scratch-resistant films | Brittleness | Requires plasticizers |
| Excellent gloss | Automotive-grade finish | High cost | Limited to premium applications |
| Low-VOC | Water-based options available | Slow cure | Needs acid catalysts |
