by What is Epoxidized Soybean Oil?
Epoxidized soybean oil (ESBO) is a common industrial chemical produced by adding epichlorohydrin to the double bonds found in unsaturated fatty acids present in soybean oil. This process, known as epoxidation, produces an oxirane ring or epoxide group in the chemical structure. It contains these epoxide groups which give it unique performance properties that are useful for several applications.
Chemical Structure and Properties
The epoxidation of soybean oil results in the formation of an oxirane ring at the location of carbon-carbon double bonds originally present in the unsaturated fatty acids. This confers new reactivity to ESBO that allows it to function as a reactive plasticizer and modifier. The epoxide groups make epoxidized soybean oil more polar and reactive compared to Epoxidized Soybean Oil. It has a higher epoxide equivalent weight range of 165-190 and oxirane oxygen content range of 4.8-5.8%. The increased polarity allows ESBO to plasticize polar resins and polymers more effectively. Its reactivity also enables further chemical reactions and linkages not possible with unmodified soybean oil.
Uses as a Plasticizer
One of the most common applications of epoxidized soybean oil is as a plasticizer for polymers like polyvinyl chloride (PVC). When added to PVC, the epoxide groups in ESBO can react with and become chemically bonded to the PVC polymer chains. This makes ESBO a reactive plasticizer that becomes permanently embedded in the material. As a result, products made with ESBO plasticized PVC have improved properties like reduced extractability, greater compatibility, higher heat resistance and lower permeability to gases compared to regular phthalate plasticizers. ESBO plasticized PVC is used widely in applications such as pipes, siding, healthcare products, flooring and wire and cable insulation where these attributes are important.
Uses in Coatings and Adhesives
The epoxide functionality of epoxidized soybean oil allows it to be used as both a reactive diluent and a crosslinking agent in liquid epoxy coatings, adhesives and sealants. Its interactions with other resins and crosslinkers extend the pot life while improving properties like adhesion, flexibility, chemical resistance and humidity resistance of the cured product. ESBO is incorporated in several commercially available two-component and one-component epoxy adhesives as well as 100% solids UV-curable liquid coatings. The coatings industry utilizes its advantages for applications on metal substrates, concrete flooring and glass fiber reinforced plastic components.
Performance as a Polyurethane Modifier
In the polyurethane industry, epoxidized soybean oil finds application as a polyol component which becomes an integral part of the urethane polymer through reaction of its epoxide groups. This modifies the physical characteristics of the resultant flexible and semi-rigid foams as well as thermoplastic elastomers. Foams made with ESBO polyols exhibit lower density and superior tensile strength, tear resistance and indentation force deflection. TPEs get enhanced low temperature flexibility from ESBO. Its hydroxyl groups also promote self-extinguishing properties in foams used in automotive and furniture applications. Overall, ESBO inclusion improves mechanical performance and complies with flammability standards.
Other Notable Uses
Apart from the major roles above, ESBO finds some specialized usage in areas like:
– Concrete admixtures – ESBO acts as a water reducing agent and increases early strength in concretes.
– Construction sealers – It provides good moisture resistance, flexibility and adhesion in sealers for basements and parking structures.
– Thermoplastic applications – ESBO can be utilized to develop biodegradable and compostable blends with polyethylene, thermoplastic starch and polybutylene succinate.
– Packaging – Its compatibility with various materials allows ESBO to be evaluated as a potential replacement for biphenyl additive in food contact applications.
Epoxidized soybean oil derived from sustainable soybean oil is a very versatile industrial chemical that performs as a plasticizer, reactive diluent and polyol due to epoxide reactivity imparted via its production process. It yields enhanced properties in various polymer systems and finds wide commercial utilization
