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Pigment Orange 36 is a bright, high-performance organic pigment used widely in plastics, coatings, and inks due to its excellent weather and lightfastness properties.
It belongs to the Benzimidazolone class of pigments.
CAS Number: 12236-62-3
Synonyms
Permanent Orange RL,Benzimidazolone Orange H5G,CI Pigment Orange 36,PO36,Irgazin Orange RLC (commercial name),Hostaperm Orange GR (commercial name)
Introduction and Overview
Pigment Orange 36 (PO36), also known by its Colour Index designation C.I. Pigment Orange 36 (C.I. 11780), is a high-performance organic pigment widely used in industrial coatings, plastics, inks, and automotive paints.
It belongs to the class of benzimidazolone pigments, recognized for their excellent heat stability, weather fastness, and vibrant chroma.
PO36 offers a reddish-orange hue that is deeper and more saturated than other orange pigments like PO13 and PO34.
The discovery of benzimidazolone pigments in the 20th century marked a significant advancement in pigment technology, providing an option for durable, non-toxic, and aesthetically versatile colorants. Pigment Orange 36 has become a mainstay in high-end applications where performance and color intensity are critical.
Chemical Identity and Structure
IUPAC Name: 1-[(4-chloro-2-nitrophenyl)azo]-2-naphthol-3-carboxylic acid, calcium salt
Molecular Formula: C17H9ClN2O4
Molecular Weight: ~341.72 g/mol
CAS Number: 12236-62-3
Chemical Class: Azo, Benzimidazolone
Color Index: C.I. 11780
PO36 is synthesized from diazotized 4-chloro-2-nitroaniline, coupled with 2-hydroxy-3-naphthoic acid (BON acid), forming a stable azo bond.
The presence of the benzimidazolone moiety enhances its resistance to solvents and UV radiation.
Synthesis and Manufacturing Processes
The synthesis of PO36 involves several critical steps:
Diazotization: 4-chloro-2-nitroaniline is diazotized using sodium nitrite in acidic medium.
Coupling: The diazonium salt is then coupled with BON acid under controlled pH and temperature.
Filtration and Washing: The pigment precipitate is filtered and washed to remove inorganic salts and unreacted materials.
Conditioning: The crude pigment is treated with surfactants and dispersants to improve dispersion properties.
Drying and Milling: Final drying and milling yield a consistent particle size suitable for industrial applications.
Process optimization focuses on enhancing yield, purity, and particle size distribution to ensure consistency and quality.
Physical and Chemical Properties
Appearance: Red-orange powder
Density: 1.6–1.9 g/cm³
Melting Point: Decomposes before melting
Heat Stability: >200°C
Lightfastness: 7-8 (Blue Wool Scale)
Solvent Resistance: Excellent
Oil Absorption: 35–45 g/100g pigment
pH Stability: Stable across a wide pH range
These properties make PO36 suitable for demanding applications requiring thermal and photochemical stability.
Spectral and Analytical Characterization
UV-Vis Spectroscopy: Maximum absorption around 480–500 nm, characteristic of its azo chromophore.
FTIR: Peaks corresponding to N=N (azo), C=O (carbonyl), and aromatic stretching modes.
NMR (Solid-state): Confirms structural integrity and substitution pattern.
XRD: Amorphous to semi-crystalline nature depending on processing.
SEM/TEM: Particle morphology typically in the range of 50–200 nm.
TGA/DSC: Thermal decomposition onset at ~300°C.
Such techniques are crucial for quality control and regulatory compliance.
Conclusion and Future Prospects
Pigment Orange 36 remains a cornerstone in the palette of industrial colorants due to its vivid hue, exceptional fastness properties, and adaptability.
As industries shift toward sustainability, research into bio-based precursors, eco-friendly processing, and hybrid pigment systems will shape its evolution.
Its role in high-performance coatings and advanced composites is expected to grow, especially in automotive, aerospace, and packaging sectors.
Continued regulatory support and innovation will ensure PO36 retains its relevance in the decades to come.
SAFETY INFORMATION ABOUT PIGMENT ORANGE 36
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
