Coating Additives

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
MT 303	Colorless viscous liquid	≥98	2000-6000	≤0.3	–	Highly methylated hexahydroxymethyl melamine resin
MT 303lf	Colorless viscous liquid	≥98	2000-6000	≤0.1	–	low free formaldehyde303
MT 303w	Colorless viscous liquid	≥96	2000-6000	≤0.5	–	303
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
MT 327	Colorless viscous liquid	88-92	5100-16000	≤0.8		Fast curing, no need for strong acid catalysis, low formaldehyde emission
MT 385	Colorless viscous liquid	76-81	1000-1600	≤0.4		Fast curing, no need for strong acid catalysis, low formaldehyde emission
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
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

 

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