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OMNIRAD 1173

Omnirad 1173 is a highly efficient Type I α-hydroxy ketone photoinitiator used in UV-curable coatings, inks, adhesives, varnishes, and 3D-printing resins, appearing as a clear to pale yellow liquid with excellent compatibility across acrylate systems.
Upon UV exposure—particularly in the 300–365 nm range—Omnirad 1173 undergoes rapid Norrish Type I cleavage to generate benzoyl and α-hydroxyalkyl radicals, enabling fast polymerization, strong crosslinking, and high-performance cured films with minimal yellowing.
Omnirad 1173's low odor, low volatility, and ability to cure thin and moderately thick films make Omnirad 1173 a preferred photoinitiator for applications requiring high clarity, good surface cure, and reliable performance under both mercury and many LED curing systems.

CAS Number: 7473-98-5
EC Number: 231-272-0
Molecular Formula: C10H12O2
Molecular Weight: 164.20 g/mol

Synonyms: 1-Hydroxy-1-methylethyl phenyl ketone, 1-Phenyl-2-hydroxy-2-methyl-1-propanone, 1-Phenyl-2-methyl-2-hydroxypropanone, 2-Benzoyl-2-hydroxypropane, 2-Benzoyl-2-propanol, 2-Hydroxy-2-benzoylpropane, 2-Hydroxy-2-methyl-1-phenyl-1-propanone, 2-Hydroxy-2-methyl-1-phenylpropan-1-one, 2-Hydroxy-2-methyl-1-phenylpropane-1-one, 2-Hydroxy-2-methyl-1-phenylpropanone, 2-Hydroxy-2-methyl-1-propiophenone, 2-Hydroxy-2-methyl-propylphenone, 2-Hydroxy-2-methylphenylpropanone, 2-Hydroxy-2-methylpropiophenone, 2-Hydroxy-2,2-dimethylacetophenone, 2-Hydroxy-methylphenylpropan-1-one, 2-Methyl-2-hydroxy-1-phenyl-1-propanone, 2-Methyl-3-phenyl-3-oxopropan-2-ol, 2,2-Dimethyl-2-hydroxyacetophenone, Hydroxy dimethyl acetophenone, NSC 401744, α-Hydroxy-α-methylpropiophenone, α-Hydroxy-α,α-dimethylacetophenone, α-Hydroxyisobutyrophenone, α,α-Dimethyl-α-hydroxyacetophenone

Omnirad 1173 is a highly efficient Type I free-radical photoinitiator used in UV-curable formulations to initiate polymerization under ultraviolet or LED light.
Omnirad 1173 appears as a clear to pale yellow liquid, offering excellent compatibility with a wide range of oligomers, monomers, and reactive diluents used in coatings, inks, adhesives, varnishes, wood finishes, and 3D-printing resins.

Omnirad 1173 is valued for its low viscosity, high solubility, and rapid photolysis, generating benzoyl and α-hydroxyalkyl radicals upon UV exposure, which efficiently initiate polymerization of acrylates and other unsaturated systems.
Omnirad 1173's low odor, minimal yellowing tendency, and ability to cure both thin and moderately thick films make it suitable for transparent coatings, overprint varnishes, and high-clarity systems where color retention is critical.

The photoinitiator performs well in 300–365 nm UV ranges, and is compatible with medium-pressure mercury lamps and many LED sources.
Because Omnirad 1173 has relatively low volatility and migration properties, Omnirad 1173 is also used in electronics coatings and other high-performance applications where thermal stability and optical clarity are essential.

Overall, Omnirad 1173 is regarded as a versatile, fast-acting photoinitiator that delivers consistent curing performance, excellent formulation compatibility, and high efficiency in UV-curable technologies.

Omnirad 1173 is a highly efficient, low yellowing, Type I photoinitiator used to initiate radical polymerization of unsaturated oligomers e.g. acrylates, after exposure to UV light.
Omnirad 1173 can be used in combination with mono or multi functional monomers as reactive diluents.

Omnirad 1173 is a versatile highly efficient liquid photo initiator which is used to initiate the photo polymerization of chemically unsaturated prepolymers – e.g., acrylates – in combination with mono- or multifunctional monomers.

Omnirad 1173 is a multifunctional liquid photoinitiator for converting UV-curable varnishes to acrylics on paper, metal, and plastic surfaces.
Omnirad 1173 is particularly recommended for UV coatings, with only slight yellowing even after prolonged exposure to sunlight.

Omnirad 1173 has good compatibility and is easily mixed with other photoinitiators and prepolymers.
Omnirad 1173 is used in conjunction with the light stabilizer Sinolstab292, which further reduces yellowing of acrylic system polyurethane under outdoor sunlight.

Omnirad 1173 is a highly efficient, low yellwoing type I photoinitiator.
Omnirad 1173 provides surface-, through-, LED and high speed cure.
Omnirad 1173 is used to initiate radical polymerization of unsaturated oligomers such as acrylates after exposure to UV light.

Omnirad 1173 can be used in combination with mono or multi functional monomers as reactive diluents.
Omnirad 1173 is suitable for clear-, white-, pigmented- and water-based systems.

Omnirad 1173 is recommended for use in adhesives & graphic arts.
The shelf life of Omnirad 1173 is 36 months.

Omnirad 1173 is a widely used Type I alpha-hydroxy ketone photoinitiator designed for high-efficiency free-radical polymerization in UV-curable coatings, inks, adhesives, sealants, and 3D-printing resins.
Omnirad 1173 is supplied as a low-viscosity, water-clear to slightly yellow liquid that blends easily with a broad range of acrylate monomers and oligomers, making it one of the most versatile and formulation-friendly photoinitiators in the UV-curing industry.

Upon exposure to UV light—particularly in the 300–365 nm absorption range—Omnirad 1173 undergoes rapid Norrish Type I α-cleavage, generating highly reactive benzoyl and α-hydroxyalkyl radicals.
These radicals initiate fast and efficient crosslinking of multifunctional acrylates, resulting in coatings and films with excellent hardness, scratch resistance, adhesion, and chemical durability.
Because of its fast photolysis and broad compatibility, Omnirad 1173 is especially preferred for thin-film applications, clear coatings, overprint varnishes, plastic coatings, optical layers, and wood finishes where color stability and high transparency are required.

Omnirad 1173’s low odor, low volatility, and reduced yellowing tendency make it suitable for sensitive applications, including electronics coatings, optical adhesives, and high-end packaging inks.
Omnirad 1173 also exhibits good performance under many modern LED curing systems, contributing to high reactivity even in oxygen-rich environments, which typically inhibit surface cure in free-radical processes.

In addition, Omnirad 1173's liquid form simplifies handling, metering, and incorporation into formulations, eliminating the dusting and dispersion issues associated with solid photoinitiators.
Omnirad 1173 is often used alone but can be combined with other photoinitiators—such as phosphine oxides or benzophenone derivatives—to optimize depth cure, surface cure, or spectral response.

Market Overview of Omnirad 1173:
The global market for Omnirad 1173 is strongly driven by the rapid expansion of UV-curable technologies, particularly in high-performance coatings, printing inks, adhesives, and 3D-printing resins.
As industries increasingly shift toward energy-efficient, solvent-free, and fast-curing production processes, demand for liquid photoinitiators such as Omnirad 1173 continues to grow.
UV-curable systems enable manufacturers to reduce drying times, lower VOC emissions, minimize energy use, and increase production throughput—all major incentives in modern manufacturing environments.

A key driver of the Omnirad 1173 market is the rise of LED-UV curing, which offers lower heat generation, longer lamp life, and reduced energy consumption compared to traditional mercury lamps.
Because Omnirad 1173 exhibits strong absorption in the near-UV region (especially 300–365 nm), formulators increasingly prefer it for LED-curable printing inks, overprint varnishes, and high-performance coatings for plastics, electronics, and packaging materials.

Geographically, Asia-Pacific remains the largest and fastest-growing market, fueled by strong manufacturing bases in China, South Korea, India, and Southeast Asia where UV-curable coatings and inks support automotive, electronics, packaging, and decorative materials industries.
Europe and North America maintain steady demand, particularly in high-end applications such as advanced electronics coatings, optical adhesives, 3D printing, and industrial wood coatings.
Regulatory pressures favoring low-VOC, low-odor, and environmentally friendly technologies also strengthen the adoption of Omnirad 1173 in both regions.

Another market segment experiencing growth is additive manufacturing (3D printing), especially SLA and DLP technologies, where photoinitiators are essential for resin-based systems.
Omnirad 1173 is widely used due to its rapid polymerization rate and excellent clarity, making it suitable for both functional prototypes and end-use parts.

Despite competition from alternative photoinitiators such as TPO, TPO-L, and blended photoinitiator packages, Omnirad 1173 maintains a strong market presence because of its high efficiency, excellent compatibility, low yellowing tendency, and ease of incorporation into diverse formulations.
Continued advancements in LED curing, flexible packaging, digital printing, and eco-friendly coatings ensure that demand for Omnirad 1173 will remain robust in the coming years.

Applications of Omnirad 1173:
Omnirad 1173 is one of the most widely used photoinitiators in UV-curable technologies due to its high efficiency, low odor, and excellent compatibility with acrylate-based systems.
Omnirad 1173's primary use is in UV-curable coatings, where it enables rapid polymerization of clear and pigmented systems for plastics, wood, paper, metals, and electronic components.
Omnirad 1173 is especially valued in overprint varnishes (OPVs), plastic coatings, wood finishes, and protective topcoats, where fast cure speed, low yellowing, and high optical clarity are essential.

In the printing industry, Omnirad 1173 is widely used in UV-curable inks, including flexographic, screen, lithographic, and digital inkjet formulations.
Omnirad 1173 helps achieve instant curing, high gloss, excellent adhesion, and scratch resistance, making it suitable for packaging, labels, commercial printing, and high-speed industrial printing lines.

A rapidly growing application is in 3D-printing resins—especially SLA and DLP systems—where Omnirad 1173 provides fast initiation, smooth layer formation, and high-resolution curing.
Omnirad 1173's low color and liquid form allow formulators to produce highly transparent or pigmented resins without affecting optical performance.

In adhesives and pressure-sensitive applications, Omnirad 1173 enables quick bonding and crosslinking for UV-curable glues used in electronics assembly, medical devices, optical components, label stock, and industrial laminates.
Omnirad 1173's rapid cure response helps reduce cycle times and supports automated manufacturing processes.

Beyond conventional applications, Omnirad 1173 is also used in electronic coatings, conformal coatings, photoresists, and specialized radiation-curable polymer systems, where low migration, low odor, and compatibility with multifunctional acrylates are critical.

In terms of chemical structure and properties, Omnirad 1173 is highly effective and, most importantly, does not cause yellowing.
This property is of great importance for unsaturated polyester systems and UV curing systems composed of multifunctional monomers.

In these complex chemical systems, Omnirad 1173 acts as an elegant conductor, methodically directing the curing reaction.
Not only does Omnirad 1173 have the advantage of low odor, preventing unpleasant pungent odors during use, but it also exhibits excellent color stability.

This color stability acts as a faithful guardian of the color kingdom, ensuring the cured product retains Omnirad 1173's original color for a long time without annoying yellowing problems.
Omnirad 1173's also worth noting that it has excellent compatibility and can be easily combined with other photoinitiators, like puzzle pieces, to achieve even greater effects.

In a wide range of practical applications, Omnirad 1173 has proven to be extremely versatile.
Take acrylic photocuring varnish systems as an example.

They can be used on everything from delicate wood products and robust metal equipment to common paper and various types of plastics.
If we look at the evolution of the furniture manufacturing industry over the years, in the early days before the advent of this highly effective photoinitiator, varnish on wood surfaces often took a long time to cure, and the varnish was prone to discoloration and other problems.
The introduction of Omnirad 1173 was like a powerful booster shot into the industry, significantly improving production efficiency and product quality.

In modern industry, UV plastic coatings, UV wood coatings, UV paper inks, and other areas are inseparable from the presence of Omnirad 1173.
Omnirad 1173 is a hero behind the scenes in these areas, quietly driving the development of the industry.

Market research data shows that products using Omnirad 1173 have significantly improved in terms of quality consistency and market acceptance.
This is due not only to Omnirad 1173's excellent performance but also to the adaptability of the colorless system to specific needs.

In addition, Omnirad 1173 complements 907 and exhibits a synergistic effect, particularly when used in conjunction with TPO and 819 in UV-curable coatings and inks, transparent wood coatings, plastics and metals, and overprint varnishes.
Omnirad 1173's safe to assume that these complex industrial application scenarios would be problematic without the presence of Omnirad 1173.

For example, in the printing of plastic films, if color is unstable or the curing is incomplete, Omnirad 1173 rejection rate will increase significantly, resulting in significant economic losses for the company.
Applying Omnirad 1173 is like wearing a solid layer of armor for these industries, ensuring smooth production and high product quality.

From a deeper chemical perspective, the molecular structure of Omnirad 1173 dictates that it can efficiently generate free radicals under UV light irradiation, thus initiating a polymerization reaction.
This sensitive chemical reaction mechanism is the key reason why it stands out among many photoinitiators.
Moreover, Omnirad 1173's adsorption and reactivity on different material surfaces have also undergone extensive experimental research and optimization, providing a solid theoretical basis for its wide application.

Omnirad 1173 may be used after adequate testing for applications such as UV-curable clear coatings based on acrylates for paper, metal and plastic materials.
As a liquid UV curing agent with excellent compatibility, Omnirad 1173 is especially easy to incorporate.

Omnirad 1173 is therefore highly suitable for blends with other photo initiators.
Omnirad 1173 is especially recommended when UV coatings are required to exhibit only minimal yellowing even after prolonged exposure to sunlight.
Yellowing of urethane acrylates may be further reduced by addition of hindered amine light stabilizer Omnistab LS 292.

Benefits of Omnirad 1173:
Omnirad 1173 offers a combination of high reactivity, excellent compatibility, and superior optical performance, making it one of the most widely used photoinitiators in UV-curable technologies.
Omnirad 1173's fast α-cleavage mechanism produces highly reactive radicals that initiate polymerization rapidly, enabling extremely short cure times even under low-intensity UV or LED lamps.

This makes Omnirad 1173 ideal for high-speed production lines and applications requiring immediate hardening or handling.
One of Omnirad 1173's most significant advantages is low yellowing, allowing formulators to achieve water-clear, color-stable coatings and inks.

This is particularly important for transparent varnishes, wood finishes, electronics coatings, and optical adhesives where visual clarity is essential.
The liquid nature of Omnirad 1173 also provides easy handling and incorporation, eliminating dusting issues common with solid photoinitiators and ensuring uniform distribution in acrylate systems.

Omnirad 1173 demonstrates excellent compatibility with a wide range of monomers, oligomers, and reactive diluents, giving formulators exceptional flexibility in designing coatings, inks, and adhesives with tailored mechanical and chemical resistance.
Omnirad 1173 also performs well in oxygen-inhibited environments, improving surface cure and reducing tackiness in thin films.
Because it cures efficiently under both traditional mercury lamps and many LED sources, Omnirad 1173 supports the transition to energy-efficient, low-heat LED curing systems.

From a performance perspective, the photoinitiator helps achieve hard, scratch-resistant, chemically durable films with strong adhesion to plastics, wood, paper, metals, and electronic substrates.
Omnirad 1173 also contributes to improved gloss, smoothness, and mechanical integrity of cured films.
Overall, Omnirad 1173 provides a combination of high curing efficiency, optical clarity, formulation versatility, and processing convenience, making it a preferred photoinitiator in modern UV-curable technologies.

Production of Omnirad 1173:
The production of Omnirad 1173 involves a multi-step organic synthesis designed to create a high-purity α-hydroxy ketone with strong photoinitiating efficiency.
Manufacturing typically begins with the preparation of the aromatic precursor—most commonly acetophenone derivatives—which undergo controlled functionalization to introduce the α-methyl and α-hydroxy substituents that define the molecule’s photochemical reactivity.
These steps generally include Friedel–Crafts acylation, selective alkylation, or ketone modification reactions performed in closed reactors under carefully regulated temperature, pH, and catalyst conditions to ensure high conversion and minimal side-product formation.

Once the core ketone structure is formed, the intermediate may undergo hydroxylation or rearrangement reactions in the presence of acid or base catalysts to generate the characteristic α-hydroxy group essential for Norrish Type I photolysis.
Reaction solvents such as aromatic hydrocarbons, esters, or alcohols are used to control viscosity, promote mixing, and improve reaction kinetics.
After the main synthetic step, the mixture is subjected to neutralization, solvent removal, vacuum distillation, and fine filtration to eliminate trace impurities, unreacted feedstock, and low-molecular-weight by-products.

The purification phase is critical, as photoinitiator performance is highly sensitive to contaminants that can inhibit radical formation, cause yellowing, or reduce curing speed.
Manufacturers employ high-efficiency fractional distillation, activated carbon polishing, and final product clarification to achieve the required optical clarity and chemical purity.
Stabilizers or antioxidants may be added in trace amounts to protect the initiator from premature oxidation during storage.

The final product—a clear to pale yellow, low-viscosity liquid—is then subjected to rigorous quality-control testing, including spectral absorption analysis (UV–Vis), GC/HPLC purity profiling, viscosity measurement, color evaluation, and photoreactivity assessment under standardized UV light sources.
Once approved, Omnirad 1173 is packaged in light-protected, airtight containers to prevent degradation from UV exposure and oxidation.

Through this carefully controlled manufacturing process, producers ensure that Omnirad 1173 meets the high performance, purity, and consistency requirements needed for UV-curable coatings, inks, adhesives, and 3D-printing formulations.

Synthesis of Omnirad 1173:
The synthesis of Omnirad 1173 follows a controlled organic pathway designed to build the α-hydroxy ketone structure responsible for its photoinitiating performance.
Production begins with an aromatic acetophenone precursor, typically acetophenone or a closely related substituted derivative.

This precursor undergoes α-alkylation, where a methyl group is introduced at the carbon adjacent to the carbonyl, creating 2-methylacetophenone.
This transformation is typically carried out using alkylating reagents in the presence of strong bases or Lewis-acid catalysts under carefully regulated reaction conditions to control selectivity and suppress side reactions.

The resulting α-methyl ketone intermediate is then subjected to a controlled hydroxylation step, where a hydroxyl group is introduced at the same α-carbon.
This step may be achieved by reaction with peracids, peroxides, or other electrophilic oxygenating agents that can selectively convert the α-position into the hydroxy functional group without over-oxidation.
The hydroxylation reaction is often performed in inert, temperature-regulated reactors to minimize decomposition or formation of unwanted by-products.

Following hydroxylation, the crude product contains Omnirad 1173 along with residual reactants, solvents, and trace impurities.
The material is therefore processed through neutralization, solvent stripping, and vacuum distillation, which purifies the α-hydroxy ketone and removes low-boiling and thermally sensitive components.
Additional polishing steps—such as activated carbon treatment or fine filtration—ensure the final product meets the stringent clarity and purity requirements demanded by UV-curable applications.

Once purified, Omnirad 1173 undergoes quality-control testing, including UV-Vis absorption profiling, GC/HPLC purity analysis, color evaluation, and photoreactivity assessment.
Only batches that demonstrate correct spectral response and high photoinitiation efficiency are released for use.
The final product is packaged in light-protected containers to prevent photodegradation during storage and shipping.

Through this multistep synthesis—combining alkylation, selective hydroxylation, and high-purity refinement—manufacturers produce Omnirad 1173 with the performance consistency required for coatings, 3D-printing resins, inks, and advanced UV-curable systems.

History of Omnirad 1173:
The history of Omnirad 1173 is closely tied to the development of UV-curing technology, which began gaining industrial momentum in the late 1960s and early 1970s.
During this era, manufacturers sought alternatives to solvent-based coatings and inks, which created VOC emissions, long drying times, and high energy consumption.

Early photoinitiators such as benzoin ethers provided basic UV reactivity but suffered from yellowing, odor issues, and limited compatibility with newer acrylate formulations.
As demand grew for cleaner, faster, and more efficient curing systems, researchers began synthesizing a new class of α-hydroxy ketone photoinitiators, engineered to deliver higher reactivity and lower coloration.

By the 1980s, Omnirad 1173 emerged as one of the most successful molecules in this new generation.
Omnirad 1173 offered several advantages that quickly made it a preferred option: low odor, low yellowing, high solubility, and exceptional curing speed under mercury-lamp UV sources.
Omnirad 1173's liquid form further differentiated it from earlier solid photoinitiators, offering easier incorporation and eliminating dusting problems in manufacturing environments.

The widespread industrial adoption of UV-curing technology through the 1990s—particularly in printing, packaging, electronics, and wood coatings—cemented Omnirad 1173's position as a workhorse photoinitiator.
When LED curing began to expand in the early 2000s, Omnirad 1173 retained its relevance due to its ability to absorb in the near-UV region, enabling strong performance under many LED wavelengths.
This versatility allowed the photoinitiator to remain a staple ingredient even as curing technology evolved.

Today, Omnirad 1173 is recognized as one of the most important and historically influential photoinitiators in the UV-curable industry.
Omnirad 1173's combination of speed, clarity, and formulation compatibility has made it a benchmark reference point for both traditional mercury-lamp systems and newer LED-based curing platforms.

Stability and Reactivity of Omnirad 1173:

Chemical Stability:
Omnirad 1173 is stable under normal ambient conditions and maintains its reactivity profile when stored properly in sealed, light-protected containers.

Reactivity:
Omnirad 1173 is not highly reactive under standard handling conditions but can decompose when exposed to strong UV light, intense heat, or incompatible chemicals.

Conditions to Avoid:
Direct sunlight, ultraviolet radiation, strong oxidizing agents, and elevated temperatures may accelerate degradation or discoloration.

Hazardous Decomposition Products:
Thermal or photolytic decomposition may release irritating fumes, including carbon monoxide, carbon dioxide, and low levels of organic vapors.

Hazardous Polymerization:
Polymerization is not expected to occur.

Handling and Storage of Omnirad 1173:

Handling:
Use only in well-ventilated areas and avoid contact with eyes and skin.
Do not expose Omnirad 1173 to open UV sources during mixing or transfer.
Avoid inhaling vapors or aerosols that may form during heating.

Storage:
Store in tightly sealed, opaque containers to prevent light exposure.
Keep in a cool, dry location away from heat sources, ignition points, and incompatible chemicals.
Prevent moisture ingress and maintain containers upright at all times.

Incompatibilities:
Avoid storage near strong oxidizers, strong acids, and reactive peroxide compounds.

First Aid Measures of Omnirad 1173:

Inhalation:
Move the affected person to fresh air and allow them to breathe comfortably.
Seek medical attention if coughing, dizziness, or respiratory irritation persists.

Skin Contact:
Wash the skin thoroughly with mild soap and water.
Remove contaminated clothing.
If redness or irritation develops, obtain medical advice.

Eye Contact:
Immediately flush eyes with clean water for at least 15 minutes, holding eyelids open.
Get medical assistance if irritation continues or vision changes occur.

Ingestion:
Rinse mouth with water.
Do not induce vomiting unless advised by medical personnel.
Seek medical attention promptly.

Firefighting Measures of Omnirad 1173:

Suitable Extinguishing Media:
Use dry chemical, CO₂, foam, or water spray depending on surrounding fire conditions.

Specific Hazards:
Although Omnirad 1173 is not highly flammable, heating may produce irritating or toxic fumes.
Containers exposed to fire may rupture due to pressure buildup.

Protective Equipment:
Firefighters should wear self-contained breathing apparatus (SCBA) and full protective clothing to avoid exposure to combustion vapors.

Accidental Release Measures of Omnirad 1173:

Personal Precautions:
Wear protective gloves and eye protection.
Ensure adequate ventilation.
Prevent direct contact with liquid and avoid breathing vapors.

Environmental Precautions:
Prevent entry into drains, surface water, or soil.
Large releases should be contained to avoid environmental impact.

Cleanup Procedure:
Absorb spilled material with inert absorbents such as sand, clay, or industrial absorbents.
Place collected material in appropriate disposal containers.
Clean the area using detergent and water to remove residues.

Exposure Controls / Personal Protective Equipment of Omnirad 1173:

Engineering Controls:
Use local exhaust ventilation or general mechanical ventilation to reduce vapor accumulation, especially during curing or heating operations.

Respiratory Protection:
Not typically required under normal conditions.
Use a respirator with organic vapor cartridges if vapors mist or fumes are generated above recommended limits.

Eye Protection:
Wear chemical splash goggles or safety glasses with side shields.

Skin Protection:
Use chemical-resistant gloves (nitrile, neoprene) and long-sleeved protective clothing to minimize exposure.

Hygiene Measures:
Wash hands thoroughly after handling.
Do not eat, drink, or smoke while working with the material.

Identifiers of Omnirad 1173:
Product Name: Omnirad 1173
Chemical Name: 2-Hydroxy-2-methylpropiophenone
Synonyms: HMPP, Darocur 1173, Irgacure 1173
Chemical Type: Type I photoinitiator (α-hydroxy ketone)
CAS Number: 7473-98-5
EC Number: 231-272-0
Molecular Formula: C₁₀H₁₂O₂
Molecular Weight: 164.20 g/mol
Appearance: Clear to pale yellow liquid
Odor: Mild, characteristic
Solubility: Soluble in organic solvents; low water solubility
Primary Use: UV-curable coatings, inks, adhesives, 3D-printing resins
Packaging: Light-protected HDPE or metal containers

Chemical Name : 2-hydroxy-2-methyl-1-phenyl-propan-1-one
Molecular weight : 164.2 g/mol g/mol
CAS No. : 7473-98-5

Name: Omnirad 1173
Chemical Identity: α-Hydroxy ketone photoinitiator
IUPAC Name: 2-Hydroxy-2-methylpropanophenone
CAS: 7473-98-5
EC No.: 231-272-0
Formula: C₁₀H₁₂O₂
Physical Form: Clear liquid
Color: Colorless to light yellow
Odor: Mild aromatic odor
Solubility: Soluble in organic monomers/solvents
Primary Function: Free-radical photoinitiator for UV/LED curing
Usage Areas: Coatings, inks, adhesives, 3D-printing resins

Properties of Omnirad 1173:
Appearance: Clear, low-viscosity liquid
Color: Colorless to pale yellow
Odor: Mild aromatic/ketonic odor
Solubility: Miscible with acrylate monomers and organic solvents; low water solubility
Photoreactivity: Undergoes fast Type I α-cleavage to generate radical species
UV Absorption: Strong absorption in the 300–365 nm region
Volatility: Low, suitable for high-performance coatings
Stability: Light-sensitive; degrades upon UV exposure
Compatibility: Highly compatible with acrylates, oligomers, and reactive diluents
Migration Tendency: Low compared to many solid photoinitiators
Color Stability: Minimal yellowing in cured films

Physical form colorless to slightly yellow liquid
Odor slight
Density at 20 °C (68 °F) ~ 1.08 g/cm3
Melting point 4 °C (39 °F)
Boiling point at 0.13 mbar 80–81 °C (176–178 °F)
Flash point > 100 °C (212 °F)
Viscosity at 20 °C (68 °F) ~ 25 mPa . s

Specifications of Omnirad 1173:
Product Type: Type I photoinitiator (α-hydroxy ketone)
Chemical Name: 2-Hydroxy-2-methylpropiophenone
Purity: Typically ≥ 98% (supplier-dependent)
Physical Form: Clear liquid
Color Index: Max. pale yellow
Odor Level: Mild aromatic odor
Density (25°C): ~1.03 g/cm³
Viscosity: Low-viscosity liquid
Refractive Index (20–25°C): ~1.53
UV Absorption Peak: Approx. 325 nm
Water Content: Very low; product is hydrophobic
Packaging: Light-protected HDPE or metal containers
Shelf Life: 12–24 months in sealed containers
Storage Conditions: Cool, dry, and protected from UV exposure