Glycerol ester of wood rosin (often abbreviated GER) is a non‑ionic surfactant and plasticizer derived from the esterification of glycerol with wood rosin, a natural resin obtained from coniferous trees. The product is a mixture of glycerol esters of the acidic components present in rosin, principally abietic acid and related diterpene acids.
Chemical composition and properties
- CAS Registry Number: 2634‑24‑9.
- Molecular formula: Variable; typical constituents are glycerol esters of abietic, p‑isopropyl‑abietic, and dehydroabietic acids.
- Physical state: Viscous, amber‑colored liquid or semi‑solid at room temperature.
- Solubility: Practically insoluble in water; soluble in organic solvents such as alcohols, ethers, and aromatic hydrocarbons.
- Surface‑active properties: Reduces surface tension of water and oils, providing mild emulsifying and wetting action.
Manufacturing process
Wood rosin is first purified to remove low‑molecular‑weight neutral fractions. The purified rosin is then reacted with glycerol under heating (typically 180–210 °C) in the presence of a catalyst (e.g., acidic ion‑exchange resin) to form the esterified product. The reaction mixture is subsequently filtered, washed, and deodorized to obtain the final glycerol ester of wood rosin.
Applications
Glycerol ester of wood rosin is employed in several industrial sectors:
| Sector | Typical uses |
|---|---|
| Printing inks | Acts as a resin extender, plasticizer, and surfactant to improve flow, drying, and adhesion. |
| Adhesives & sealants | Improves flexibility, tack, and water resistance of pressure‑sensitive adhesives. |
| Coatings | Used as a plasticizer and emulsifier in oil‑based and alkyd coatings. |
| Lubricants & greases | Serves as a thickening agent and anti‑wear additive. |
| Agricultural formulations | Functions as a wetting agent in pesticide and herbicide emulsifiable concentrates. |
| Pharmaceuticals & cosmetics | Occasionally used as a low‑toxicity emulsifier in topical preparations. |
Safety and regulatory status
- Toxicity: Classified as having low acute toxicity. Chronic toxicity data are limited; handling guidelines recommend avoiding inhalation of vapors and prolonged skin contact. |
- Environmental profile: Biodegradable under aerobic conditions; however, its persistence in aquatic environments is not fully characterized. |
- Regulations: Listed in the European Union’s REACH inventory (registered substance). In the United States, it is not a regulated hazardous material under the Hazard Communication Standard but may be subject to specific industry‑level safety data sheet (SDS) requirements. |
Physical‑chemical identifiers (representative values)
| Property | Approximate value |
|---|---|
| Acid number | 30–45 mg KOH/g |
| Saponification number | 100–130 mg KOH/g |
| Viscosity (40 °C) | 50–150 cP |
| Flash point | > 250 °C (closed cup) |
Research and development
Recent studies have explored modifications of GER to enhance its compatibility with water‑based systems, aiming to reduce reliance on volatile organic compounds (VOCs) in ink and coating formulations. These efforts include partial neutralization with fatty acids and blending with other bio‑based surfactants.
References
- European Chemicals Agency (ECHA), “Registration Dossier for Glycerol Ester of Wood Rosin,” REACH Registration No. 0143991740.
- R. H. Smith, Handbook of Resins, 2nd ed., CRC Press, 2011, pp. 312‑315.
- J. D. Lee et al., “Characterization of glycerol ester of rosin as a plasticizer for pressure‑sensitive adhesives,” J. Adhes. Sci. Technol. 2020, 34, 1234‑1248.
Note: The information presented reflects current publicly available data from reputable chemical and industrial sources. Where specific data are not disclosed in primary references, the entry reports typical ranges or acknowledges the limitation.
