Suspension concentrate (SC)
Suspension concentrate (SC) formulations, also known as "flowables" (F), consist of having a solid active ingredient dispersed in the water while emulsifiable concentrate (EC) formulations combine an active ingredient dissolved in a solvent with emulsifiers.
SCs have grown in popularity due to benefits such as the absence of dust, ease of use, and effectiveness when compared to other formulation types such as ECs and wettable powder (WP) - powder formulations that form a suspension when mixed with water before spraying.
To formulate a stable SC in agrochemicals such as pesticides, the solid particles of the active ingredient must remain insoluble and suspended under all temperature conditions.
Benefits
- Water based hence it provides good safety and user convenience
- Suitable for many active ingredients with low water solubility
- Absence of dust
- Absence of flammable liquids
- Small particle size of the active ingredient
- Adjuvants can be built-in for bio enhancement
Limitations
- Not compatible with water soluble active ingredients
- Crystal growth can be a problem if the active is partially soluble in water
- Long term stability issues Stability upon dilution
The processing of SC formulations involves several key steps, including preparing xanthan gum, creating the mill base, bead milling, adding preservative, and observing for flocculation that may impact particle size distribution and formulation stability. Additionally, a rheology modifier is included to finalise the formulation. Polysaccharide thickeners build viscosity within the continuous phase through controlled incompatibility with water. Explore our existing SC formulation recipes here.
Products recommended for SC
The use of polymeric dispersants is highly recommended due to their higher molecular weight, large repulsive barrier and many anchoring groups per molecule. This enables highly loaded, stable suspension concentrates to be formulated. We have a range of dispersants each with a specific area of high performance.
Atlox™ 4917
Atlox™ 4919
Atlox™ 4915
Atlox™ 4913
Atlox Metasperse™ 500L
Atlox Metasperse™ 650S
Atlox™ PN-100
Zephrym™ PD3315
It is important to include a wetting agent as during the milling process, fresh surfaces are generated which are generally of non-polar nature and will flocculate together rapidly. This could lead to increased viscosity and even mill blockage. Including a wetting agent overcomes this as it replaces air and prevents agglomeration, allowing dispersants to perform. Wetting agents can also provide some dispersion.
Atlas™ G-5002L
Atlas™ G-5004 LD
Atlox™ 4894
If an SC is not properly structured, the formulation can breakdown resulting in solid particles settling to the bottom of the formulation. This leads to reduced shelf life stability and poor performance in the field. The inclusion of a rheology modifier helps overcome this issue by increasing the viscosity of the formulation, providing improved stability.
Atlox Rheostrux™ 300A
In comparison to OD formulations, where the continuous oil phase acts as an adjuvant, SC formulations can be considered less efficacious due to the continuous phase being water. To enhance the bioavailability of the active ingredient, adjuvants can be incorporated in SC formulations.