A guide to bisphenol A — what it is, why epoxy and polycarbonate producers buy it, and how it's specified — from a US-based distributor.
Bisphenol A (BPA) is a white crystalline solid used as a difunctional monomer for epoxy resins and polycarbonate. It is made by condensing phenol with acetone. Stratus Chemical supplies industrial-grade bisphenol A at 99.80% minimum purity, in bags and supersacks, with COA and SDS.
| Chemical name | Bisphenol A |
|---|---|
| IUPAC name | 4,4′-(Propane-2,2-diyl)diphenol |
| CAS number | 80-05-7 |
| EC / EINECS number | 201-245-8 |
| Molecular formula | C15H16O2 |
| Molecular weight | 228.29 g/mol |
| Synonyms | BPA, 4,4′-isopropylidenediphenol, 2,2-bis(4-hydroxyphenyl)propane, p,p′-isopropylidenebisphenol |
| Appearance | White flake, prill, or crystalline solid |
| Grade supplied | Industrial / polymer grade |
| Packaging | Bags, supersacks |
| Item | Specification |
|---|---|
| Purity (dry basis), wt% | ≥ 99.80 |
| Phenol, ppm | ≤ 100 |
| Water, wt% | ≤ 0.100 |
| Freezing point, °C | ≥ 156.5 |
| Methanol color, APHA | ≤ 20.0 |
| Iron, ppm | ≤ 1.00 |
| Ash, ppm | < 20 |
| Molten color, APHA | ≤ 30 |
Bisphenol A is a diphenol: two phenol rings joined through the central carbon of a propane bridge, leaving a hydroxyl group at the para position of each ring. It is produced by the acid-catalyzed condensation of two moles of phenol with one mole of acetone, historically over hydrochloric acid and now generally over a sulfonated ion-exchange resin, with water as the byproduct. Because phenol and acetone are both large-volume petrochemicals, BPA pricing moves with those two markets rather than independently.
Those two hydroxyl groups are the entire commercial point of the molecule. They give BPA a functionality of two, so it can react at both ends and extend a polymer chain rather than terminating it. At the same time, the two aromatic rings and the bulky quaternary carbon between them make the resulting backbone stiff and thermally stable. A difunctional monomer that also contributes rigidity and heat resistance is an unusual combination, and it is why BPA became the standard building block for two very large polymer families.
The largest single use. BPA is reacted with epichlorohydrin under alkaline conditions to produce diglycidyl ether of bisphenol A, universally abbreviated DGEBA, which is the backbone of most commercial epoxy resins. Varying the BPA-to-epichlorohydrin ratio controls molecular weight and takes the product from a liquid resin through to a solid one. These resins go into protective and marine coatings, tank and pipe linings, structural and construction adhesives, flooring, fiber-reinforced composites, and the copper-clad laminates used for printed circuit boards. The rigidity, adhesion, and chemical resistance that make epoxies worth specifying trace directly back to the BPA unit in the chain.
The second major outlet. BPA is polymerized with phosgene, or by melt transesterification with diphenyl carbonate, to give polycarbonate — a transparent engineering thermoplastic with high impact strength and good dimensional stability. It is used in glazing and safety equipment, automotive lighting and interior components, electrical and electronic housings, and optical media.
Smaller volumes go into unsaturated polyester, polysulfone, and polyetherimide resins, and into the manufacture of certain phenolic antioxidants, flame-retardant intermediates, and PVC heat stabilizers.
Formulators evaluating epoxy systems usually end up comparing these two, so it is worth stating the trade-off plainly.
| Bisphenol A | Bisphenol F | |
|---|---|---|
| Bridge between rings | Propane (two methyl groups) | Single methylene |
| Liquid resin viscosity at 25 °C | Higher, typically 11,000–14,000 mPa·s | Lower, typically 2,000–4,500 mPa·s |
| Crystallization in storage | More prone | More resistant |
| Rigidity and glass transition | Higher | Slightly lower |
| Availability and cost | Volume standard, lower cost | Specialty, higher cost |
| Typical uses | General-purpose epoxy coatings, adhesives, laminates | Solvent-free and high-solids coatings, thick-film linings |
Bisphenol A is the default for good reasons: it is the cheapest route to a stiff, high-performance epoxy and it is available in volume from many sources. Where it loses is viscosity. A standard liquid DGEBA resin is thick enough that solvent-free and high-build formulations become difficult to apply, and it will crystallize in a drum left in a cold warehouse, which is a genuine nuisance on site. Bisphenol F resin solves both problems and gives marginally better chemical resistance, but it costs more, comes from fewer sources, and gives up a little heat resistance. Many commercial systems split the difference and use a blend.
Bisphenol A is among the most extensively studied industrial chemicals in commerce, and it carries restrictions in food-contact and certain consumer applications in a number of jurisdictions. It is also listed as a substance of very high concern under EU REACH. Requirements differ by market and have changed repeatedly, so buyers supplying into a regulated end use should confirm the current position for their own market and application rather than relying on a general statement. Stratus Chemical supplies bisphenol A for industrial polymer, resin, and coatings manufacture.
Store cool, dry, and out of direct sunlight in closed containers, away from oxidizing agents and strong bases. The two color specifications on the data sheet exist because BPA discolors: prolonged exposure to heat and air develops color, and dissolved iron picked up from unlined equipment or damaged packaging accelerates it. That is also why the iron limit is set as low as 1 ppm — it is a color control as much as a purity measure. Where BPA is handled molten, minimize hold time and hold temperature, and blanket with nitrogen if the system allows it.
In flake and prill form the material can cake under humid conditions or under stacking pressure, so keep pallets covered and rotate stock. Dust generated during transfer should be controlled at the source. Consult the SDS for the full hazard classification and personal protective equipment requirements before handling.
COA and SDS are provided with every shipment.
Bisphenol A (BPA) is used almost entirely as a monomer for polymers. Its largest use is in epoxy resins, where it is reacted with epichlorohydrin to make the resins behind protective coatings, structural adhesives, composites, and electrical laminates. Its second largest use is polycarbonate. Stratus Chemical supplies industrial-grade bisphenol A to US resin and coatings manufacturers.
The CAS number for bisphenol A is 80-05-7 and its EC number is 201-245-8. Its molecular formula is C15H16O2 and its molecular weight is 228.29 g/mol. It is also listed under the names 4,4′-isopropylidenediphenol and 2,2-bis(4-hydroxyphenyl)propane.
Bisphenol A is made by the acid-catalyzed condensation of two moles of phenol with one mole of acetone, traditionally over hydrochloric acid and now generally over a sulfonated ion-exchange resin catalyst. Water is the byproduct. Because both feedstocks are large-volume petrochemicals, bisphenol A pricing tends to track phenol and acetone markets.
Bisphenol A has a propane bridge between its two phenol rings, while bisphenol F has a single methylene bridge. Epoxy resin made from bisphenol A is the industry standard and gives higher rigidity and glass transition temperature, but it is more viscous and prone to crystallizing in storage. Bisphenol F epoxy is much less viscous, which suits solvent-free and high-solids coatings, and it resists crystallization better.
Freezing point is the classical purity indicator for bisphenol A. Pure bisphenol A freezes at about 157 °C, and isomers or residual phenol depress that point measurably, so a specification of 156.5 °C minimum corresponds to very high purity. It is a fast bulk check that complements the chromatographic assay.
Bisphenol A should be stored cool, dry, and out of direct sunlight in closed containers, away from oxidizing agents and sources of iron contamination. It discolors on prolonged exposure to heat and air, which is why commercial grades carry both a methanol color and a molten color specification. Flake and prill forms can cake under humidity or stacking pressure.
Stratus Chemical supplies industrial-grade bisphenol A at 99.80% minimum purity on a dry basis, with phenol at 100 ppm maximum and iron at 1.00 ppm maximum, in bags and supersacks. Tell us your form and volume requirement and we will respond with pricing and availability within one business day.
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