Oil dispersion (OD)
An oil dispersion (OD) formulation is a solid active ingredient dispersed in oil. The oil can vary from paraffinic to aromatic solvent types and vegetable oil or methylated seed oils. Ideally the active ingredient is uniformly suspended in the oil phase.
ODs are an excellent delivery system for water sensitive active ingredients such as sulfonylureas. However, ODs have extended to other active ingredients due to their better spray retention, spreading and foliar uptake as the carrier oil often acts as an adjuvant.
Benefits
- Especially suited to hydrolytically unstable actives allowing them to be formulated as liquid formulations
- The oil continuous phase acts as a built-in adjuvant
- The oil adjuvant can provide both penetration enhancement and spray retention enhancement
- Does not need preserving (water free)
Limitations
- Can suffer from more sedimentation compared to water based systems
- Difficult to formulate
The Formulator's Toolbox (Full Version)
Oil Dispersion Step-by-Step Guide
Formulating with Water Sensitive Herbicides
Developing microbial oil dispersion (OD) formulations
Products recommended for OD
Aqueous dispersants are used in some cases in order to improve stability in the spray tank after dilution in water. If the active ingredient is insoluble in water and needs to be suspended for a length of time, the aqueous dispersant will prevent flocculation of these solid particles and improve overall stability.
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Atlox Metasperse™ 550S
A modified styrene acrylic polymeric aqueous dispersant in powder form. Particularly suited for highly loaded solid formulations such as WP or WDG, ideally combined with Multiwet MO-85P.
Atlox™ 4915
A polymeric amphoteric aqueous dispersant optimised for performance in electrolyte conditions and water free composition allows for use in OD formulations. Additional benefits as adjuvant for...
Emulsifiers are necessary in order to emulsify the continuous oil phase into water when the OD formulation is diluted prior to being sprayed. Emulsifiers are selected based upon their ability to spontaneously form this emulsion. Their performance is primarily dictated by the nature of the surfactant and their collective effect on how they arrange themselves at the oil/water interface.
Atlas™ G-1086
A single emulsifier for vegetable and closely related oils. Initial testing shows good compatibility with microbes and an OMRI Listed version is available.
Atplus™ 300F
Recommended emulsifier package for crop oil concentrates
Atplus™ 309F-LM
A single emulsifier system for mineral and paraffinic oils. It has low moisture content which acts to minimise antagonistic interactions with some active ingredients.
Atlox™ 4838B
An oil-soluble anionic emulsifier for improved stability and blooming of formulations upon dilution. Commonly used as part of a triangle screen formulation approach.
Non-aqueous dispersants disperse the active ingredient in the oil continuous phase and provide long term stability. In an OD formulation, solid particles are susceptible to flocculation, leading to an increase in particle size and formulation instability. To prevent this, the use of a polymeric dispersant is highly recommended.
Atlox™ 4916
A low HLB polymeric emulsifier and non-aqueous dispersant, with a unique star structure, which provides exceptional stability. As an emulsifier it is commonly used in combination with Atlas™ G-5002L.
Atlox™ 4914
A nonionic random polymeric surfactant with low HLB value which can be used as an emulsifier or non-aqueous dispersant. Multiple PEG anchoring groups allow for good long term stability in complex...
Atlox™ LP-1
An anionic polymeric surfactant recommended for use as a non-aqueous dispersant. Carboxylic acid based anchoring groups give optimum performance with inorganics such as micronutrients.
Zephrym™ PD2206
A nonionic non-aqueous dispersant for oil dispersions. Polyethylene oxide based anchoring groups optimise performance for synthetic organic active ingredients.
Oil composition and quality may impact formulation performance either upon production or upon extended storage. Variations from oil to oil can commonly occur depending on the source so strict specifications should be applied to the chosen oil and stuck to throughout the lifetime of that material. Croda’s range of Seatons Refined Oils are 100% natural and renewable. They are also impurity free and have a good compatibility with many active ingredients, making them great options for crop care formulations.
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Seatons refined linseed oil
Seatons refined linseed oil is a simple and effective alternative to mineral oil. It is non-flammable, impurity free and has good compatibility with many agrochemical active ingredients. Natural oils...
Seatons refined rapeseed oil
Seatons refined rapeseed oil is a simple and effective alternative to mineral oil. It is non-flammable, impurity free and has good compatibility with many agrochemical active ingredients. Natural oils...
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Seatons refined soyabean oil
Seatons refined soyabean oil is a simple and effective alternative to mineral oil. It is non-flammable, impurity free and has good compatibility with many agrochemical active ingredients. Natural oils...
Rheology modifiers are an essential part of an OD formulation. If the formulation is not stabilised effectively, the solid active ingredient(s) will sediment forming a hard pack layer preventing re-dispersion. A common way to reduce this sedimentation is to increase the viscosity of the continuous phase using a rheology modifier.
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Atlox Rheostrux™ 100
Formulations containing Atlox Rheostrux 100 have improved storage stability, superior rheology profiles, reduced processing times and improved suspensibility.
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Atlox Rheostrux™ 200
Formulations containing Atlox Rheostrux 200 have improved storage stability, superior rheology profiles, reduced processing times and improved suspensibility.
