In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure O=P(OR)3, a central phosphate molecule with alkyl or aromatic substituents. They can be considered as esters of phosphoric acid.
Like most functional groups, organophosphates can be used in a diverse range of forms, with important examples including insecticides, herbicides, nerve agents, and flame retardants. OPEs have been widely used in various products as flame retardants, plasticizers, and performance additives to engine oil. The popularity of OPEs as flame retardants came as a substitution for the highly regulated brominated flame retardants. The low cost of production and compatibility to diverse polymers made OPEs to be widely used in industry including textile, furniture, electronics as plasticizers and flame retardants. These compounds are added to the final product physically rather than by chemical bond except in polymerisation.
With LANKEM we have fantastic range of OPEs. They can be used in various applications such as Agro, Coatings and Metal Cutting Fluids.
The Lanphos range of phosphate esters is a versatile class of surfactants, possessing many of the surfactant properties useful in the formulation of Industrial and Institutional cleaners than other anionic surfactants, including:
- Detergency
- Foaming
- Emulsification
- Dispersing
- Wetting
- Solubilising
In addition to these, the Lanphos phosphate esters also possess properties not as commonly found in other classes of anionic surfactant, which include:
- Defoaming
- Hydrotropicity
- High electrolyte tolerance
- Lubricity
- Corrosion inhibition
Because of the unique chemical structure of phosphate esters, it is possible to design multifunctional surfactants with the required balance of the above properties to give optimum performance in a wide range of applications in the formulation of Industrial and Institutional Cleaners.
The following is a brief introduction to the parameters which you can change in the manufacturing process and chemical composition of phosphate esters that gives rise to these properties.
Effect of Phosphorylating Route
These two phosphorylating agents give products with entirely different compositions. The following table provides typical compositions (in % weight/weight) of products made by these routes.
The choice of phosphorylating agent is essential as the monoester and diester phosphate esters have differing properties. The following table lists the typical differences:
| | Phosphorous Pentoxide | Polyphosphoric Acid |
| Monoester % | 30 – 75% | 80 – 90% |
| Diester % | 60 – 20% | 2% |
| Phosphoric acid % | 0.50% | 5 – 10% |
| Free nonionic % | 5 – 15% | 1 – 10% |
| Monoester | Diester | |
| Hydrotropicity | Excellent | Poor |
| Electrolyte tolerance | Excellent | Poor |
| Detergency | Fair | Good |
| Wetting | Fair | Excellent |
| Emulsification | Excellent (emulsion polymer) | Excellent (oils) |
| Foaming | Higher | Lower |
| Dispersing | Fair | Excellent |
The choice of hydrophobe has as significant an effect on the performance of phosphate esters as does the synthesis route. As previously stated, you can base phosphate esters on ethoxylated nonionic surfactants; however, there are some applications where unethoxylated products are used, such as fatty alcohols. The following table lists some of the properties that you can obtain with the various hydrophobes available:
| Hydrophobe | Properties |
| Fatty alcohol’s (C8 – C18) | Very low foaming/defoaming |
| Poly Aromatic | Excellent Dispersing |
| (C8 – C10) | Excellent wetting, good detergency low(ish) foaming |
| (C10 – C14) | Fair wetting, good detergency, high(ish) foaming, good emulsification (emulsion polymer) |
| (C14 – C18) | Poor wetting, poor detergency, excellent lubricity, good emulsification (oil) |
| Phenol | Excellent hydrotropicity, good lubricant additive |
In addition to the chemical nature of the hydrophobe, the degree of ethoxylation also greatly effects the performance of phosphate esters. The following table lists some of the general trends observed when changing the level of ethylene oxide:
| EO Content | Properties |
| 1 – 5 moles ethylene oxide | Good wetting, good emulsification (oils) |
| 5 – 15 moles ethylene oxide | Good emulsification (emulsion polymer), good dispersing, high electrolyte tolerance |
The Lanphos range of phosphate esters is specially developed optimising the above parameters to give exceptional performance in a wide range of applications using the expertise gained over many years of product development. Lankem is open to developing products that meet specific customer needs.
Electrolyte Tolerant Detergents
Phosphate esters can commonly find use in the formulation of highly built detergents. The high electrolyte solubility of these products allows detergents containing high levels of builders, such as caustic soda, silicates, and sequestrants, to be formulated without the need for a hydrotrope. Products for this application include:
- Lanphos PE245
- Lanphos PE36
- Lanphos TE43
Hydrotropes
Phosphate esters-based hydrotrope are amongst the most effective products, allowing the formulation of products containing up to 30% caustic soda.
The following products are in our current range:
- Lanphos TEP4
- Lanphos TEP4K
Lanphos Phosphate Ester Recommended Ffor Agrochemicals Applications
Emulsifiers – Phosphate esters find use in the formulation of emulsifiable concentrates. However, they more commonly find application in more specialised formulations such as suspo-emulsions (suspension concentrates produced in an emulsion). In these formulations, the combination of good emulsification with dispersing makes them an ideal surfactant. Products used include Lanphos PE35 and Lanphos PE36 Dispersants – Phosphate esters find use as the primary dispersant in the formulation of suspension concentrates and water-dispersible granules. They allow the formulation of stable dispersions with high solid contents.
Products used include:
- Lanphos PET22
- Lanphos PE35
- Compatibility Agents – Phosphate esters can be used to allow the spray application of pesticide at the same time as micronutrients such as manganese sulphate. In this application, it is the hydrotropic and electrolyte tolerance that makes phosphate esters suitable.
Products used include:
- Lanphos TEP4
- Lanphos TEP4K
- Lanphos PE310
Phosphate Ester in Metal Working Fluid:
Phosphate esters find application in the formulation of metal working as versatile multipurpose additives. The capability to modify their characteristics by selecting the optimum hydrophobe, ethylene oxide content and monoester to diester ratio allow products with the optimum surface-active properties to be provided for a wide range of metalworking fluid applications.
The key characteristics are:
- Emulsification
- Lubrication / Extreme pressure additive
- Corrosion inhibition
- Low foaming
- Detergency
- Hydrotropes
These characteristics can be optimized for use in the formulation of a wide range of metalworking products, including:
- Neat oils
- Soluble oils
- Semisynthetic MWF
- Synthetic MWF
- Metal cleaning formulation
Phosphate Ester in Polymerisation/Dispersion:
Phosphate Ester offers high stability towards temperature, electrolytes, and pH. They also help emulsions smooth working in hard water and ensure fine particles, high solids, and high molecular weight. It is compatible with most of the monomers and ensures durability to emulsions.
- Products Used
- Lanphos PS 10
- Lanphos PET 11
Typical products used in the formulation of metalworking fluids include:
1. Lanphos PE74 – Oil-soluble phosphate ester is a highly effective emulsifier that provides excellent lubrication in oil and water-based systems. Also, it imparts good anti-corrosion properties and low foaming characteristics to water-based lubricant systems. Lanphos PE74 can best be used in the formulation of soluble oils and semi-synthetic metalworking fluids but can also find uses in neat oils.
2. Lanphos TEP4 – Water-soluble phosphate ester is a highly effective lubricant for water-based systems, imparting good anti-corrosion properties and low foaming characteristics to water-based lubricant systems. Lanphos TEP4 can be used in the formulation of synthetic metalworking fluids. Also, it provides hydrotrope properties and can be used in the formulation of highly built-metal cleaning products.
3. Lanphos PE35 – Oil-soluble phosphate ester with moderate water solubility and good emulsification characteristics that provides good lubrication in oil and water-based systems. Also, it imparts good anti-corrosion properties and low foaming characteristics to water-based lubricant systems. Lanphos PE35 can best be used in the formulation of soluble oils and semi-synthetic and synthetic metal working fluids, particularly for aluminum cutting and forming fluids. Lanphos PE35 can also be used in the formulation of highly built metal cleaning products often, in combination with Lanphos TEP4.
