PIGMENT ORANGE 64

Description:
Pigment Orange 64 is an organic pigment widely used for its bright orange color in inks, plastics, paints, coatings, and printing applications. 
It belongs to the azo pigment class, characterized by the presence of azo groups (-N=N-) linking aromatic rings, which give the pigment its vivid color and good stability.

It is known for its good lightfastness, heat stability, and chemical resistance, making it suitable for a variety of industrial and artistic uses.
CAS Number: 12227-43-9
Synonyms:
C.I. Pigment Orange 64,C.I. 12075,Benzidine Orange,Diarylide Orange,Pigment Orange B, 3,3'-Dimethyl-4,4'-benzidine-based azo pigment

Abstract
Pigment Orange 64 (PO64) is a synthetic azo pigment extensively utilized in a variety of industrial applications such as coatings, plastics, inks, and rubber due to its vibrant orange hue, excellent color strength, and good resistance to weathering and heat. 
This article provides a comprehensive scientific review of PO64, covering its chemical structure and molecular characteristics, synthetic pathways, physicochemical and performance properties, industrial applications, environmental and health considerations, and analytical techniques for its characterization. 
The document also discusses comparative pigments and future trends in pigment technology. Understanding these facets is essential for optimizing the use of PO64 in advanced materials and ensuring compliance with environmental and safety regulations.

Keywords
Pigment Orange 64, azo pigment, organic pigment, pigment synthesis, color properties, industrial pigments, environmental impact, pigment analysis.

Introduction
Organic pigments represent a vital class of colorants extensively employed in industrial sectors such as coatings, plastics, printing inks, and textiles.
Among these, azo pigments constitute the largest group, characterized by their versatile chemical structure featuring azo (-N=N-) linkages between aromatic systems. 
Pigment Orange 64 (PO64) is a prominent member of this group, known for its bright orange coloration, high tinting strength, and durability.

Since its commercial introduction, PO64 has gained widespread application due to its superior fastness properties compared to conventional orange pigments. 
The pigment’s molecular design, incorporating chlorinated aromatic rings and pyrazolone coupling components, confers enhanced thermal and chemical stability, making it suitable for demanding applications.

This article aims to provide a thorough scientific overview of PO64, exploring its chemical structure, synthesis methods, physicochemical properties, performance under various conditions, and its applications across industries. 
Additionally, environmental, toxicological, and regulatory considerations are discussed alongside analytical methodologies used for pigment characterization.

Chemical Structure and Molecular Characteristics
Pigment Orange 64 (CAS number 5468-75-7) belongs to the diazo class of azo pigments. 
Its molecular formula is C30H24Cl2N6O4, with an approximate molecular weight of 595.46 g/mol. 
The pigment molecule features two azo groups (-N=N-) bridging aromatic rings, specifically chlorinated phenyl groups and pyrazolone rings.

Molecular Architecture
The core structure of PO64 consists of a symmetrical azo compound synthesized by diazotization of chlorinated anilines followed by azo coupling with pyrazolone derivatives. 
The presence of chlorine atoms on the phenyl rings significantly influences the electron density, contributing to the pigment’s characteristic absorption in the visible spectrum, resulting in its vivid orange color.

The pyrazolone moiety provides resonance stabilization of the azo bond and contributes to the pigment's thermal and light stability. 
This conjugated system facilitates strong absorption in the visible region, making PO64 a highly chromatic pigment.

Polymorphism and Crystallinity
Pigments often exist in polymorphic forms, affecting their hue, dispersibility, and stability. PO64 typically crystallizes in an orthorhombic system with well-defined crystal habits, contributing to its dispersibility and optical properties. The pigment's crystalline nature also influences its thermal stability and resistance to chemical degradation.

Synthesis and Production Methods
The industrial synthesis of Pigment Orange 64 involves a multi-step chemical process focusing on diazotization and azo coupling reactions.

Raw Materials
Aromatic amines: Primarily 2-chloroaniline or its derivatives, serving as diazotization precursors.
Coupling agents: Pyrazolone derivatives such as 1-phenyl-3-methyl-5-pyrazolone.
Acids and reagents: Hydrochloric acid for diazotization, sodium nitrite as the nitrosating agent.

Diazotization
The aromatic amine undergoes diazotization in acidic aqueous media, where sodium nitrite reacts with the protonated amine to form a diazonium salt. 
The reaction temperature is typically maintained between 0–5 °C to stabilize the diazonium intermediate and prevent decomposition.

Azo Coupling
The diazonium salt reacts with the pyrazolone coupling component under controlled pH (usually slightly alkaline, pH ~7-9) to form the azo pigment. 
The reaction is exothermic and requires careful temperature control to ensure optimal particle formation.

Isolation and Purification
The crude pigment precipitates during the coupling reaction and is filtered, washed thoroughly to remove inorganic salts and residual reactants, and then dried. 
Milling or micronization reduces particle size to achieve the required dispersion properties.

Surface Treatment
To improve dispersibility and compatibility with different media, the pigment surface may be treated with dispersants or coatings such as silica or aluminum hydroxide.

Physicochemical Properties
Appearance and Color
PO64 appears as a reddish-orange to bright orange powder with high color strength. 
It exhibits excellent tinting strength and is favored for its intense chroma in various matrices.

Particle Size and Morphology
Typical particle sizes range from 0.2 to 0.5 micrometers. Electron microscopy reveals irregularly shaped crystals with smooth surfaces that facilitate uniform dispersion in media.

Thermal Stability
Thermogravimetric analysis indicates that PO64 maintains stability up to approximately 300 °C, beyond which decomposition initiates. 
This thermal resistance is adequate for processing in thermoplastics and high-temperature coatings.

Solubility
PO64 is practically insoluble in water and most organic solvents, which is desirable for color fastness and migration resistance. 
Minor solubility in solvents like dimethylformamide (DMF) is observed.

Spectral Properties
UV-Vis spectroscopy: Exhibits absorption maxima around 450 nm, corresponding to the azo chromophores.

FTIR spectroscopy: Characteristic peaks include azo N=N stretching (~1400 cm^-1), aromatic C=C stretches (~1600 cm^-1), and carbonyl stretching (~1650 cm^-1) from pyrazolone groups.

Raman spectroscopy: Confirms the conjugated azo system and aromatic substitutions.

Performance Characteristics
Lightfastness
PO64 exhibits excellent resistance to photodegradation. 
Accelerated weathering tests using Xenon arc lamps demonstrate minimal color change (ΔE < 2) after 500 hours, making it suitable for outdoor applications.

Chemical Resistance
The pigment withstands exposure to acids, bases, and common solvents used in coatings and plastics without significant discoloration or degradation.

Heat Stability
The pigment can tolerate high processing temperatures typical in polymer extrusion (up to ~280 °C) with negligible loss of color or decomposition.

Dispersibility and Compatibility
PO64 disperses readily in acrylic, polyester, and polyurethane binders, yielding homogenous color without bleeding. 
Its compatibility extends to various polymer matrices including polypropylene, polyethylene, and PVC.

Applications of Pigment Orange 64
Coatings
Widely used in automotive and industrial coatings, PO64 imparts vibrant coloration with durability against UV exposure, chemical attack, and mechanical wear.

Plastics
PO64 is incorporated into masterbatches for coloring thermoplastics, providing excellent weatherability and color consistency in molded parts, films, and fibers.

Printing Inks
Used in flexographic, gravure, and screen printing inks, PO64 enhances print brightness and fastness properties.

Rubber and Textiles
In rubber formulations, it improves aesthetic appeal without compromising mechanical properties. Textile printing utilizes PO64 for bright orange hues resistant to washing and light exposure.

SAFETY INFORMATION ABOUT PIGMENT ORANGE 64

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