What Is Light Aromatic Naphtha?
Light aromatic naphtha, often referred to as Aromatic 100 type solvent, is a narrow petroleum cut made up almost entirely of C8 to C10 aromatic hydrocarbons. It is a clear, colourless liquid with a mild characteristic aromatic odour and it flows freely at room temperature. Unlike a single chemical, it is a defined mixture whose behaviour is described by distillation range, aromatic content and solvency rather than by a single melting point.
Its CAS number is 64742-95-6. The main constituents are trimethylbenzenes, xylenes, ethylbenzene and cumene, with minor amounts of higher alkylbenzenes. Because the aromatic ring is present, the solvent dissolves resins, rubbers and oils that aliphatic hydrocarbons such as mineral spirits cannot touch, while the relatively high boiling range keeps evaporation slow enough for good film flow and levelling.
Typical Properties and Composition
| Property | Typical value |
|---|---|
| CAS number | 64742-95-6 |
| Chemical nature | complex mixture of C8 to C10 aromatic hydrocarbons |
| Main components | trimethylbenzene, xylene, ethylbenzene, cumene |
| Appearance | clear, colourless liquid |
| Odour | mild aromatic |
| Boiling range, ASTM D86 | approximately 155 to 185 degrees C |
| Flash point, closed cup, ASTM D93 | approximately 40 to 45 degrees C |
| Auto-ignition temperature | above 400 degrees C |
| Relative density at 20 degrees C | about 0.86 to 0.88 |
| Aromatic content | typically above 99 percent |
| Kauri-butanol value | about 90 and higher |
| Water solubility | practically insoluble, floats on water |
Because the cut is defined by its distillation range rather than by a single specification, boiling range, flash point and density vary slightly between producers and between seasonal batches. Buyers should fix the distillation window, aromatic content and sulphur level in the purchase specification, and treat the table above as indicative.
Why It Dissolves So Many Resins
Solvency in this solvent comes from the aromatic ring, which interacts strongly with the aromatic and polar groups present in alkyd, acrylic, epoxy, polyester, chlorinated rubber and vinyl resins. The practical consequences are a high Kauri-butanol value, a low aniline point and good tolerance for the resin solutions used in coatings, inks and adhesives.
Its evaporation profile is the second half of the story. A distillation window around 155 to 185 degrees C gives a slower evaporation rate than toluene or xylene, so a coating keeps enough open time to flow out and level, and an ink keeps enough solvent to avoid drying in the press nip. Aromatic naphtha is therefore frequently blended with faster aromatics to dial in the exact drying curve that a coating or ink line needs.
Rubber, Adhesive and Sealant Applications
In rubber compounding the solvent acts as a softener and processing aid. It swells the elastomer, lowers compound viscosity and hardness, and makes mixing, calendering, moulding and extrusion easier. It also improves tack, which helps the adhesion of rubber to fabric, cord, metal inserts and other rubber plies, and it contributes to flexibility and low-temperature performance in the finished article.
In adhesives and sealants it dissolves the base polymer and any tackifying resin so the adhesive can be applied at a controlled viscosity. Because it evaporates evenly, the dried film is uniform and the bond strength is repeatable across wood, leather, plastics, metal and foil substrates. The same combination of solvency and controlled evaporation is used in contact cements, pressure-sensitive adhesive coatings and solvent-borne sealants.
Coatings, Inks and Chemical Uses
Coatings and paints. It dissolves resins, pigments and additives to give a coating good flow and levelling, helps form a smooth uniform film, and speeds up drying after application, which shortens handling time and reduces dust pickup on the wet film.
Printing inks. It dissolves resins and colourants so the ink has the flow and transfer properties needed for even deposition, and it allows the drying rate to be tuned so the ink neither dries in the press nor smudges on the printed surface.
Chemical feedstock. Aromatic naphtha is a raw material for the production of benzene, toluene and xylene through separation and reforming routes, and it serves as an extraction solvent in purification steps where a selective aromatic phase is required.
Other uses. It appears in industrial cleaning and degreasing blends, in agrochemical and oilfield formulations as a carrier solvent, and as a diluent in resin and polymer processing where a slower aromatic solvent is preferred to xylene.
Handling, Storage and Safety
Light aromatic naphtha is a flammable liquid: its closed-cup flash point lies in the 40 to 45 degrees C band and its vapour is heavier than air, so ignition sources, hot surfaces and static discharge must be controlled. Drums and tanks should be bonded and earthed during transfer, and work areas should be ventilated because inhalation of the vapour causes irritation and drowsiness. Skin contact defats the skin and should be avoided with nitrile gloves and suitable protective clothing.
Store the product in steel drums or dedicated tanks under a nitrogen or dry-air blanket, away from oxidising agents, strong acids and direct sunlight, at temperatures below 40 degrees C. Keep containers closed to limit evaporation and moisture ingress. With these precautions, shelf life is typically twelve to twenty-four months in sealed, well-ventilated storage.
Frequently Asked Questions
Q: What is light aromatic naphtha used for?
Its main uses are as a solvent in coatings and paints, printing inks, adhesives and rubber processing, and as a feedstock or extraction solvent for benzene, toluene and xylene production.
Q: What is the CAS number of light aromatic naphtha?
The CAS number is 64742-95-6, the petroleum naphtha cut that is rich in C8 to C10 aromatic hydrocarbons.
Q: How does it differ from xylene or toluene?
It is a mixture rather than a single compound, and it boils higher than xylene and toluene, so it evaporates more slowly and gives longer open time in coatings and inks.
Q: Is light aromatic naphtha flammable?
Yes. It is a flammable liquid with a closed-cup flash point in the 40 to 45 degrees C range, and it must be handled with bonding, earthing and ventilation.
Q: Can it replace aliphatic mineral spirits?
It dissolves aromatic-ring and polar resins that aliphatic spirits cannot, but its stronger odour and higher solvency mean it is usually blended rather than substituted one for one.
Q: What should be fixed in the purchase specification?
Distillation range, aromatic content, flash point, density, colour and sulphur level should all be specified, because the cut varies between producers and batches.