What are the main industrial use of ethylene glycol (1,2-Ethanediol)

Ethylene glycol (EG), also known as 1,2-Ethanediol, is a colorless, odorless, sweet-tasting viscous liquid with the molecular formula C₂H₂O₂. As one of the most basic diols, EG, due to its unique physical and chemical properties, has become an indispensable key raw material in the global chemical industry. Its industrial applications are extremely broad, particularly in polyester fiber manufacturing and high-performance antifreeze formulations. It is a key indicator of the development level of a country's fine chemical and synthetic materials industries.

Core Monomers in the Polyester Industry Chain: The Cornerstone of Polyester and Bottle Flakes

The largest industrial use of EG is as one of the main monomers in the synthesis of polyethylene terephthalate (PET). According to industry data, approximately 90% of global EG consumption is concentrated in the polyester industry chain.

1. A Critical Raw Material for Polyester Fiber Production

PET is produced by esterification or transesterification of EG with purified terephthalic acid (PTA) or dimethyl terephthalate (DMT).

Polyester Filament Yarn and Staple Fiber: Polyester fiber, commonly known as polyester, is widely used in clothing, home textiles (such as bed sheets and curtains), and industrial textiles (such as tire cord and conveyor belts) due to its excellent wrinkle resistance, dimensional stability, high strength, abrasion resistance, and quick-drying properties. The global textile industry's enormous demand for polyester has directly driven the continued expansion of EG production capacity.

Industry Driven: As an upstream raw material, EG's price fluctuations and supply stability directly impact the cost structure and market competitiveness of the midstream and downstream polyester industry.

2. Polyester Bottle Resin and Film

In addition to fiber, another major application of PET is the production of polyester bottle flakes and films.

Packaging Applications: PET bottle flakes offer excellent barrier properties, transparency, and lightweight advantages, making them a preferred material for packaging carbonated beverages, drinking water, cooking oil, and various foods.

Functional Films: Polyester films (such as BOPET film) play a key role in high-tech fields such as electronics, optical displays, photovoltaic backsheets, packaging, and magnetic recording materials.

An Irreplaceable Component in High-Performance Antifreeze and Coolants

A second important and critical industrial application of ethylene glycol is as a core raw material for antifreeze and coolants. This is primarily due to its ability to significantly lower the freezing point and simultaneously raise the boiling point of the solution when mixed with water.

1. Antifreeze for Automotive Cooling Systems

In cold regions, antifreeze is essential for automotive engine cooling systems to prevent damage to the radiator and engine components due to ice expansion.

Freezing Point Depression: While pure water has a freezing point of 0°C, the freezing point of an aqueous solution of EG decreases significantly with increasing EG concentration. For example, a 50% EG aqueous solution can lower the freezing point to approximately −37°C, effectively ensuring normal engine operation in extremely cold conditions.

Boiling Point Increase: EG's high boiling point (197.3°C) makes its aqueous solution boiling higher than pure water, helping prevent engine overheating under high load conditions and improving the efficiency and safety of the cooling system.

Corrosion Inhibition: Industrial-grade antifreeze also contains corrosion inhibitors to neutralize the acidic substances produced by EG oxidation, protecting metal components in the cooling system (such as aluminum, copper, and cast iron) from corrosion.

2. Industrial Cooling and Heat Transfer Medium

EG is also widely used as a heat transfer medium in large industrial facilities, refrigeration systems, HVAC systems, and aircraft de-icing fluids.

Aircraft De-icing: EG or its derivatives (such as diethylene glycol) are the main components of aircraft de-icing and anti-icing fluids, used to remove ice and snow from wings and fuselages to ensure flight safety.

Other Fine Chemical Applications

Ethylene glycol is also involved in the synthesis of a variety of fine chemicals and plays an important role in other industrial fields.

1. Solvents and Plasticizers

Solvents: EG has excellent solubility and is a good solvent for nitrocellulose, resins, inks, and certain organic dyes. Its derivatives, such as glycol ethers, combine the properties of ethers and alcohols and are widely used as high-performance solvents in the coatings, paints, and detergents industries.

2. Synthetic Intermediates

Unsaturated Polyester Resins (UPRs): Ethylene glycol is a key raw material for the production of unsaturated polyester resins, which are widely used in fiberglass reinforced plastic (FRP) products, building materials, and automotive parts.

Explosives: Ethylene glycol can be used in nitration reactions to prepare ethylene glycol nitrate (EGDN), a liquid explosive component with high energy properties.