Melamine, Cyanuramide, Triaminotriazine, S-Triazinetriamine, 108-78-1, 94977-27-2

MELAMINE

Melamine / Cyanuramide / Triaminotriazine / s-Triazinetriamine
CAS Number: 108-78-1 (primary); 94977-27-2 (secondary/alternate)
EC Number: 203-615-4

1. PRODUCT IDENTIFICATION AND CHEMICAL IDENTITY

Melamine is a nitrogen-rich organic compound belonging to the triazine family. Its chemical structure consists of a 1,3,5-triazine ring with three amino groups (-NH₂) attached at the 2, 4, and 6 positions. This highly stable, symmetric structure gives melamine its unique properties, including high thermal stability, chemical resistance, and the ability to form thermosetting resins with formaldehyde. Melamine is primarily used as a raw material for the production of melamine-formaldehyde (MF) resins, which are thermosetting polymers known for their hardness, durability, chemical resistance, and flame retardancy. It is a white, odorless, crystalline powder with a high nitrogen content (approximately 66% by weight), making it valuable in flame retardant systems and certain chemical applications. The compound is synthesized industrially from urea through thermal conversion at 350-400°C, with ammonia released as a byproduct. It is commercially available in 25 kg bags as the standard industrial packaging.

2. PHYSICAL AND CHEMICAL PROPERTIES

Melamine is a white, odorless, crystalline powder with a density of 1.574 g/cm³ at 20°C. It has a high melting point of approximately 354°C, but it does not truly melt; instead, it decomposes at temperatures above 345°C. It sublimes (transitions directly from solid to vapor) under vacuum at temperatures of 250-300°C. The compound has low solubility in water at room temperature (3.24 g/L at 20°C), but solubility increases significantly in hot water (53 g/L at 100°C). It is sparingly soluble in most organic solvents but slightly soluble in glycols such as ethylene glycol and glycerol. The high nitrogen content of approximately 66.6% by weight is a key characteristic of melamine, making it valuable in flame retardant applications and as a nitrogen source in certain chemical processes. The aqueous solution is slightly basic with a pH of 7.5-8.0. Melamine has a low electrical conductivity and is considered an insulating material, which is useful in electrical applications.

3. CHEMICAL PROPERTIES AND REACTIONS

Melamine's chemical behavior is dominated by its highly stable triazine ring and the three reactive amino groups (-NH₂) attached to the ring. These functional groups enable a wide range of chemical reactions.

Resin Formation (Reaction with Formaldehyde):

The most important chemical reaction of melamine is its polycondensation with formaldehyde to form melamine-formaldehyde (MF) thermosetting resins:

C₃H₆N₆ + 6 HCHO → C₃H₆N₆·(CH₂OH)₆ (methylol melamine formation)

The methylol derivatives then undergo condensation to form cross-linked three-dimensional polymer networks:

~NH-CH₂OH + H₂N~ → ~NH-CH₂-NH~ + H₂O (methylene bridge formation)

~NH-CH₂OH + HO-CH₂NH~ → ~NH-CH₂-O-CH₂-NH~ + H₂O (ether bridge formation)

The resulting MF resins are hard, thermoset, chemically resistant, and thermally stable.

Reaction with Acids:

Melamine forms salts with acids due to its basic nature (the amino groups can accept protons):

C₃H₆N₆ + HCl → C₃H₇N₆Cl (melamine hydrochloride)

C₃H₆N₆ + HNO₃ → C₃H₇N₆NO₃ (melamine nitrate)

Reaction with Metal Ions:

Melamine can form complexes with metal ions such as Ag⁺, Cu²⁺, and Zn²⁺ through coordination with its amino groups and ring nitrogen atoms.

Hydrolysis:

Under strongly acidic or alkaline conditions at high temperatures, melamine can undergo hydrolysis to form ammeline, ammelide, and ultimately cyanuric acid and ammonia:

C₃H₆N₆ + 3 H₂O → C₃H₃N₃O₃ + 3 NH₃ (cyanuric acid formation)

Thermal Decomposition:

At temperatures above 345°C, melamine decomposes to form cyanuric acid, ammonia, and other volatile nitrogen-containing compounds:

C₃H₆N₆ → C₃H₃N₃O₃ + 3 NH₃ (thermal decomposition)

4. PRODUCTION METHODS

Melamine is produced industrially primarily from urea through thermal conversion. The most common process involves the reaction of urea at elevated temperatures (350-400°C) under pressure, with ammonia released as a byproduct.

Detailed Production Process (High-Pressure Urea Process):

1. Urea Feed: Urea is melted and fed into a reactor operating at 350-400°C and 10-100 atm pressure.

2. Thermal Conversion: Urea undergoes thermal decomposition to form isocyanic acid and ammonia:

   CO(NH₂)₂ → HNCO + NH₃ (isocyanic acid formation)

   Isocyanic acid then polymerizes to form melamine:

   6 HNCO → C₃H₆N₆ + 3 CO₂ (melamine formation)

3. Quenching and Cooling: The melamine-containing gas stream is rapidly cooled to prevent further decomposition and to solidify the melamine.

4. Crystallization: The crude melamine is crystallized from solution to remove impurities.

5. Purification: The crystallized melamine is purified through recrystallization or by dissolution and reprecipitation to achieve the desired purity.

6. Drying: The purified melamine crystals are dried to remove residual moisture.

7. Grinding and Packaging: The dried melamine is ground to the desired particle size and packaged in 25 kg bags, FIBCs, or bulk containers.

Chemical Reactions:

The overall reaction for melamine production from urea can be summarized as:

6 CO(NH₂)₂ → C₃H₆N₆ + 6 NH₃ + 3 CO₂

5. MELAMINE CONCENTRATIONS AND GRADES

6. APPLICATIONS AND INDUSTRIAL USES

Melamine is a versatile chemical intermediate with applications across multiple industries. Its most important use is in the production of melamine-formaldehyde (MF) thermosetting resins, which are known for their hardness, durability, chemical resistance, and flame retardancy.

6.1. Furniture and Construction Industry

Melamine-formaldehyde resins are the primary material for laminated surfaces in furniture and construction. The resins are applied to decorative paper, which is then pressed onto particleboard or MDF at high temperature and pressure. The resulting surface is extremely hard, scratch-resistant, chemical-resistant, and heat-resistant. These laminates are widely used for kitchen countertops, furniture surfaces, flooring, and decorative panels. The melamine coating provides excellent resistance to moisture, stains, and abrasion, making it ideal for high-wear applications.

6.2. Household and Professional Products

Melamine tableware is a significant application in the household products sector. The lightweight, break-resistant properties of melamine-formaldehyde resins make them ideal for plates, bowls, cups, and trays. These products are widely used in outdoor dining, casual dining, and institutional settings (e.g., schools, hospitals, prisons). Melamine foam is a unique product that is highly microporous and has excellent cleaning and sound absorption properties. Melamine foam is used in cleaning sponges for removing stubborn stains and in acoustic insulation for soundproofing applications.

6.3. Electrical and Electronics Industry

Melamine-formaldehyde resins are valued in the electrical industry for their excellent dielectric properties (electrical insulation) and heat resistance. They are used in switches, circuit breakers, connectors, and other electrical components. Melamine is also used as a flame retardant additive in various materials, including plastics, coatings, and textiles. The high nitrogen content (66%) makes it effective in flame retardant systems where it releases nitrogen gas upon heating, diluting flammable gases and reducing combustion. MF resins are used in high-performance coatings for automotive and industrial applications, providing hardness, scratch resistance, and chemical resistance.

6.4. Chemical Industry

Melamine-formaldehyde resins are the largest application of melamine in the chemical industry. These resins are used in adhesives, coatings, and laminates. MF resins are also used in textiles to provide wrinkle resistance, dimensional stability, and flame retardancy. In leather processing, they are used as tanning agents and coating materials. In the paper industry, MF resins are used as wet-strength additives to improve paper strength when wet. Melamine is also a raw material for the production of various specialty chemicals, including certain pharmaceutical intermediates and agrochemicals.

6.5. Flame Retardant Applications

Melamine is widely used as a flame retardant additive due to its high nitrogen content (66%). When heated, melamine releases nitrogen gas, which dilutes flammable gases and reduces the availability of oxygen, thus suppressing combustion. Melamine is used in intumescent coatings, which expand when heated to form a protective char layer on steel structures and other materials. It is also used as a flame retardant additive in polyurethane foams, thermoplastics, and thermosets. In textile finishing, melamine provides flame retardancy to fabrics. In rubber compounds, melamine is used as a flame retardant filler in conveyor belts, cables, and other applications.

6.6. Agriculture and Food Industry

IMPORTANT WARNING: Melamine is strictly PROHIBITED in food products and animal feed. The 2007-2008 incidents (pet food contamination and Chinese milk powder contamination) where melamine was illegally added to mimic protein content resulted in severe health issues, including kidney stones, kidney failure, and death in animals and children. Melamine is not a suitable nitrogen source for agricultural applications (fertilizers) due to its low solubility and slow nitrogen release. Conventional nitrogen fertilizers such as urea and ammonium nitrate are far more effective and cost-efficient. All national and international regulations strictly ban the use of melamine in food products and animal feed.

7. HEALTH EFFECTS AND TOXICOLOGY

Melamine has moderate acute toxicity but serious chronic health effects, particularly on the kidneys. Its toxicity is primarily due to the formation of cyanuric acid-melamine crystals in the kidneys.

7.1. Toxicological Data

7.2. Health Effects

Acute Exposure:

Chronic Exposure:

• Nephrotoxicity (Kidney Damage): Melamine's primary chronic toxicity is on the kidneys. High doses or prolonged exposure can lead to the formation of melamine-cyanurate crystals in the renal tubules, causing kidney stones, kidney damage, and potentially kidney failure.

• Melamine-Cyanurate Crystal Formation: Melamine and cyanuric acid (a melamine-related compound) can form insoluble crystals in the kidneys. These crystals can obstruct renal tubules, leading to tubular necrosis, kidney failure, and death.

• Human Exposures (2008 Chinese Milk Scandal): The 2008 Chinese milk powder scandal, where melamine was illegally added to milk powder to boost its apparent protein content, resulted in approximately 300,000 illnesses, 50,000 hospitalizations, and at least 6 deaths in infants. Affected infants suffered from kidney stones and kidney failure.

• Occupational Exposure: Workers in melamine production and processing facilities should avoid inhaling melamine dust. Proper dust control measures (local exhaust ventilation, dust collection systems) and personal protective equipment (dust masks, safety goggles) are recommended.

8. FIRST AID MEASURES

9. SAFETY INFORMATION (GHS CLASSIFICATION)

Signal Word: WARNING

Hazard Statements (H-Codes):

Precautionary Statements (P-Codes):

10. FIREFIGHTING MEASURES

11. ACCIDENTAL RELEASE MEASURES

12. STORAGE AND HANDLING

Melamine should be stored in cool, dry, well-ventilated areas, away from ignition sources and incompatible materials (strong oxidizing agents, strong acids). It is slightly hygroscopic and may cake if exposed to moisture, affecting its handling and dispersibility. Storage areas should be designed to minimize dust accumulation and prevent dust explosion hazards. Explosion-proof electrical equipment and proper grounding should be used. Containers should be kept tightly closed to prevent moisture absorption and contamination. Shelf life under proper storage conditions is typically 24-36 months.

Handling Notes:

• Avoid dust generation (use enclosed systems, local exhaust ventilation)

• Static electricity accumulation may occur; ground all equipment

• Use explosion-proof equipment in dusty areas

• Avoid breathing dust (use dust mask or respirator)

• Avoid contact with skin and eyes (use protective gloves and goggles)

• Keep away from ignition sources (combustible dust hazard)

• Do not allow material to become wet (may cake and become difficult to handle)

13. TRANSPORT INFORMATION

Melamine is not classified as a dangerous good for transport. It is shipped in 25 kg bags, FIBCs, or bulk containers. During transport, protect from moisture, impact, and excessive heat. Ensure proper labeling and documentation.

14. REGULATORY INFORMATION

Regulatory Status:

Food Contact Regulations:

15. OTHER NAMES AND SYNONYMS

Database Identifiers:

16. ENVIRONMENTAL INFORMATION

Melamine has low toxicity to aquatic organisms but is slowly biodegradable, meaning it may persist in the environment. It has low potential for bioaccumulation. In soil and water, melamine may persist for extended periods due to its slow degradation rate. Waste disposal should be carried out according to local, state, and federal regulations. Incineration at a permitted facility is recommended.

17. INDUSTRY SECTOR SUITABILITY TABLE

18. COMMON NAMES AND INDUSTRY TERMINOLOGY

19. DOWNSTREAM AND UPSTREAM PRODUCTS

19.1. Raw Materials (Upstream)

19.2. Derivative Products (Downstream)

20. SUMMARY AND CRITICAL WARNINGS

SUMMARY:

Melamine (C₃H₆N₆, CAS 108-78-1) is a nitrogen-rich heterocyclic organic compound belonging to the triazine family. It is a white, odorless, crystalline powder with a molecular weight of 126.12 g/mol, density of 1.574 g/cm³, melting point of approximately 354°C (decomposes), and low water solubility (3.24 g/L at 20°C). It has a high nitrogen content of approximately 66% by weight, making it valuable in flame retardant applications. It is produced industrially from urea through thermal conversion at 350-400°C. The most important application is in melamine-formaldehyde (MF) thermosetting resins, which are used in laminates, furniture coatings, kitchen worktops, tableware, cleaning sponges, electrical insulation, and flame retardant systems. It is also used as a flame retardant additive, in textile finishing, and in specialty chemicals. Melamine is strictly PROHIBITED in food products and animal feed due to severe health risks (kidney stones, kidney failure). The 2008 Chinese milk scandal resulted in global bans and strict regulations. Health hazards include mild skin and eye irritation, respiratory irritation, and chronic kidney damage. IARC Group 3 (not classifiable as to carcinogenicity to humans). Not classified as a dangerous good for transport. Stored in cool, dry, well-ventilated areas away from ignition sources. Packaging: 25 kg bags (standard), FIBCs, or bulk containers.

Key Properties:

Major Application Areas:

Key Safety Points:

• NEPHROTOXIC (KIDNEY TOXIN): Prolonged or repeated exposure may cause kidney damage

• PROHIBITED IN FOOD: Strictly prohibited in food products and animal feed (global regulation)

• DUST EXPLOSION: Combustible dust; may form explosive dust-air mixtures

• MILD IRRITANT: Causes mild skin and eye irritation

• RESPIRATORY IRRITANT: May cause respiratory irritation at high dust concentrations

• STORAGE: Store in cool, dry, well-ventilated area away from ignition sources

• PPE REQUIRED: Dust mask, safety goggles, protective gloves (for dust handling)

• IARC CLASSIFICATION: Group 3 (not classifiable as to carcinogenicity to humans)

CRITICAL WARNINGS:

Prohibition in Food and Feed: Melamine is STRICTLY PROHIBITED in food products and animal feed worldwide. The 2008 Chinese milk scandal, where melamine was illegally added to infant formula and milk powder to inflate protein content, resulted in approximately 300,000 illnesses, 50,000 hospitalizations, and at least 6 deaths in infants. All national and international regulations (including FDA, EU, China, and many others) strictly ban the use of melamine in food and feed products.

Nephrotoxicity (Kidney Damage): Melamine can cause severe kidney damage through the formation of insoluble melamine-cyanurate crystals in the renal tubules. These crystals can obstruct the renal tubules, causing tubular necrosis, kidney stones, kidney failure, and death. The risk is higher with co-exposure to cyanuric acid, which can occur in certain industrial settings or through metabolic conversion in the body. Chronic occupational exposure to melamine dust requires regular medical monitoring of kidney function.

Tableware Safety: Melamine tableware is considered safe for normal household use when used appropriately. However, users should avoid:

• Heating in microwave ovens (may cause degradation and migration of melamine into food)

• Prolonged contact with acidic or hot foods (>70-80°C), which may increase migration of melamine into food

• Using damaged or scratched tableware (may increase migration)

• Using for high-temperature applications (e.g., oven use)

Food Contact Regulations: Melamine is approved for indirect food contact applications (food contact materials) in many jurisdictions. However, specific migration limits (SML) apply:

• EU: 2.5 mg/kg food (EU 10/2011)

• USA: FDA 21 CFR 177.1460 (indirect food additive)

• China: 2.5 mg/kg food (GB 9685-2016)

Agricultural Applications: Melamine is NOT a suitable agricultural nitrogen source (fertilizer). Its low solubility and slow nitrogen release make it far less effective than conventional nitrogen fertilizers such as urea and ammonium nitrate. Additionally, its regulatory restrictions and high cost make it economically unviable for agricultural use.

Dust Explosion Hazard: Melamine dust can form explosive dust-air mixtures when dispersed in air at sufficient concentrations. All equipment should be grounded to prevent static charge accumulation, and dust collection systems should be used to minimize airborne dust. Explosion-proof electrical equipment is required in areas where dust may be present.

Important Disclaimer: This Technical Data Sheet (TDS) is for informational purposes only. The information provided is based on available data and is believed to be accurate. However, the user is solely responsible for determining the suitability of the product for their specific application and for complying with all applicable regulations and safety requirements. For complete safety, handling, storage, and regulatory compliance information, always refer to the official Safety Data Sheet (SDS/MSDS) provided by the manufacturer/supplier. Users are responsible for testing the product in their own processes and applications. All local, national, and international regulations must be followed when working with melamine. Melamine is strictly PROHIBITED in food products and animal feed.