css button by Css3Menu.com

Products >> Performance Chemicals >> Agri Culture >> Formulation >>Emulsifiable Concentrate(EC) Formulation

Emulsifiable Concentrate(EC) Formulation

How To Develop An Emulsifiable Concentrate (EC) Formulation

The keys to the expeditious, successful development of an Emulsifiable Concentrate (EC) formulation are planning and superb execution. It begins by asking a series of questions; the answers to which should have implications upon the development effort.

QUESTION: What is an Emulsifiable Concentrate (EC) formulation? 
An Emulsifiable Concentrate (EC) formulation is a solution of technical, organic solvent, emulsifiers, and additives.
IMPLICATION: If the formulation components are not in solution, it is not an EC. Since solubility is affected by temperature (usually, the lower the temperature, the poorer the solubility), it is necessary to specify temperature conditions under which the formulation remains in solution.

 

QUESTION: What performance factors should I consider during EC development?

It is important that the formulation be:

  1. Efficacious = the formulation must perform the task for which it was formulated;

  2. Chemically Stable = the active ingredient should not chemically degrade during the expected shelf life of the formulation;

  3. Physically Stable = the formulation components remain in solution over the expected shelf life of the formulation. Emulsification properties do not deteriorate as the product ages;

  4. Emulsification Stable = the active ingredient remains uniformly distributed in the water phase at the application rate using water of variable hardness, over the time frame and under the environmental conditions applied. Milk, which is a dispersion of fat in water, can be used as a qualitative
    standard;

  5. Physically and Chemically Stable When Tank Mixed With Other Formulations


QUESTION: What Affects Emulsion Performance?
Factors which affect emulsion performance begin with the Emulsifiable Concentrate composition and extend into the application equipment:

  1. If a super-saturated solution of the technical in solvent has been processed, crystallization may occur in the aqueous media upon dilution;

  2. If a polar solvent is used to dissolve a solid technical, crystal may for in the spray tank as a function of water temperature. The colder the water temperature, the greater the chance to form crystals;

  3. The failure of the product formula to accommodate lot to lot variability of formulation components (including technical);

  4. Application of the formulation under conditions not considered during development or subsequently tested;

  5. Incompatibility with commercial packaging (for example, the EC dissolves plasticizers used during extrusion molding which change the 'solvent' composition);

  6. Incompatibility with application seals and gaskets;

  7. Spray equipment has not been adequately cleaned between applications or has not been properly calibrated;

  8. The order of addition in which individual formulations are added to the spray tank;

QUESTION: How do I go about selecting the EC formulation emulsifier(s)?
Surfactants are selected based upon their ability to emulsify the 'solvent' into water. As alluded to above, there are factors that impact emulsion performance: water hardness, dilution rate, time, temperature, and presence of another formulation in the spray tank.
Since it is impossible to evaluate all performance factors during development, it is best to establish 'standard' conditions which best reflect overall application conditions. For example:

  • water hardness = 342ppm (standardized composition)

  • dilution rate = 5%W/W

  • time frame = overnight

  • temperature = 23°C

  • presence of another formulation in the spray tank = No


Although McCutcheon's "Emulsifier & Detergents" list in excess of 20,000 different surfactants, the basic EC emulsifier system consists of no more than four (4) components:

  1. Solid Technical

  2. Antifoam

  3. Bactericide*

  4. Surfactant

  5. Density/Viscosity Modifier System

  6. Freeze/Thaw Additive

  7. Water Diluent

* Required only where hydroxycellulose viscosity modifiers are used

 

Solid Technical : Unlike Dust and Wettable Powder formulations, where the technical can demonstrate unspecified physical properties, Suspension Concentrate formulations are premised upon two factors:

  1. a water-insoluble anionic surfactant

  2. a highly water-soluble ethoxylated nonionic surfactant

  3. a low water-soluble ethoxylated nonionic surfactant

  4. a highly water-soluble block co-polymer nonionic surfactant

 

where, upon dilution in water, the anionic surfactant is present in the 'solvent' phase and the block co-polymer nonionic surfactant is present in the water phase.

The ethoxylated nonionic surfactants function at the interface between water and the organic solvent. By their chemical composition, one end of the surfactant molecule is soluble in water; and one end is soluble in the organic 'solvent'. Ethoxylated nonionic surfactants differ, in general, based upon the composition of the hydrophobe and moles of ethylene oxide (degree of water solubility). It is by means of "balancing" the water soluble and oil soluble surfactant components (ethoxylated nonionic surfactants in combination with the anionic and block co-polymer nonionic) at the 'solvent' interface that a physically stable emulsion is formed in water.

It is important to note that the above use of the term 'solvent' refers to the sum total of the organic phase and can change with solvent composition and active ingredient concentration. In other words, a Permethrin 100g/L EC (using Aromatic 100 Solvent) may not have the same surfactant requirement as a Permethrin 100g/L EC (using Aromatic 200 Solvent) or a Permethrin 400g/L EC (using Aromatic 100 Solvent) because all three possess different 'solvent' compositions. 

Although there are an infinite number of 'solvent' compositions which require specific surfactant compositions to form physically stable emulsions, it is not necessary to have available an infinite number of surfactants with which to formulate. The emulsifier requirement for a 'solvent' dispersed in water can be accomplished by blending the four generic surfactants identified above. 

The only limiting factor with emulsifier selection is that it meet the definition of an Emulsifiable Concentrate (and whatever regulatory requirements are associated with the field of application).An example of a standard emulsifier system would be the following:

    1. Calcium Dodecylbenzenesulfonate (CaDDBSA) - anionic surfactant

    2. Nonylphenolethoxylate-6 moles (NPE6) - low water solubility ethoxylated nonionic

    3. Nonylphenolethoxylate-30 moles (NPE30) - high water solubility ethoxylated nonionic

    4. Atlas® G-5000 - high water solubility EO/PO block co-polymer nonionic Alternative emulsifiers can be substituted 1:1 for their equivalent above and evaluated.


QUESTION: How Do I Calculate A Formula?
The formula calculation should be considered as two phases:

    1. Development - Since each emulsifier used during the initial 
      development may have slightly different specific gravities, all potential emulsifier blends can be considered as having a specific gravity of 1.05 gm/mL. This one assumption will greatly reduce the amount of time required to develop a separate formula for each emulsifier combination.

    2. Final Formula - At this time, the individual emulsifier specific
      gravities are considered, at their relative ratios determined during development, in the formula calculation. The final formula should not deviate significantly from the development formula.


See TECHNICAL BULLETIN 99-01: "How To Calculate An Emulsifiable Concentrate Or Suspension Concentrate Formula"

QUESTION: How Do I Blend The Emulsifiers?
Depending upon whether the number of emulsifiers to blended are two, three, or four, will dictate the time (and sample) requirement to accomplish the task. Obviously, the more emulsifiers involved in the evaluation, the more extensive the evaluation.


See TECHNICAL BULLETIN 99-03: "Experimental Design: Blending Surfactants To Optimize Emulsification Properties"


QUESTION: How Do I Develop An Emulsifiable Concentrate Formulation?
Up to this point we have dealt with the "excellent planning" involved with EC development; now comes the "superb execution."

Step 1. Prepare the Development Formula for each surfactant in the formulation in sufficient quantity to accomplish all blending requirements. Using Permethrin 100g/L EC blending emulsifiers "A" and "B" as an example:


Sp. Gr. Composition "A"

 

"B"

1.222 permethrin(95%) 11.53 11.53
1.05 Surfactant "A" 8.50  
1.05 Surfactant "B"   8.50
0.872 Aromatic 100 Solvent 79.97 79.97
  Total 100.00 100.00

 

Formulation Specific Gravity = 0.915 gm/mL
Formulation %W/W A.I. = 10.95%

Step 2. Weigh the proportional weights of each surfactant solution into an 8-dram vial (total weight = 1.00gm) and mix until uniform. NOTE: The proportions are listed in the above TECHNICAL BULLETIN 99-03.
Step 3. Volumetrically add 19 ml of 342ppm hardness water to the 8-dram vial, cap andmix vigorously;
Step 4. Make initial observations as whether 'solvent' has formed an emulsion in water (Does it look like milk?) or immediately separates into two phases.
Step 5. Place the 8-dram vials, containing emulsion, at 23°C overnight and measure the %V/V separation when left undisturbed. 
Step 6. Correlate emulsion stability with emulsifier composition and evaluate additional emulsifier blends if warranted. Again, TECHNICAL BULLETIN 99-03 will identify alternative emulsifier blends.
Step 7. Versatility of the optimum emulsifier ratio to accommodate different application conditions (dilution rate, temperature, water hardness, etc.) can be addressed one of two ways:

  • Evaluate the optimum emulsifier ratio under the application conditions of interest and rate performance; or

  • Re-evaluate the emulsifiers ratios under the alternative application conditions and identify emulsifier ratios which are common to both (or more) conditions. This may lead to the determination that sacrifice must be made in product 
    performance under each condition in order to have the 'best' emulsifier ratio to accommodate both conditions.

Step 8. Recalculate the Development Formula, using the exact %W/W of each emulsifier and their respective specific gravities, to determine the Final Formula. 
Step 9. Prepare sufficient quantity of the Final Formula to evaluate both Emulsifiable Concentrate and Emulsion Performance Criteria identified above.

QUESTION: Is the formulation development complete?
The short answer is: "No"; the reasons being that::

  1. Alternative suppliers for all raw materials should always be identified and confirmed. Obviously, this can become quite involved as the number of raw materials and their suppliers increase;

  2. Periodically, at least on a yearly basis, formula performance should be confirmed using raw materials that reflect current supplier production;


GENERAL RECOMMENDATIONS FOR EMULSIFIABLE CONCENTRATE FORMULATION



JEEMOX Pair FORMULATION SOLVENT RATIO DOSAGE (%)
771
A
772
B
Pendimethalin (30) Aromax 80/20, 75/25, 70/30 5-6
771
A
772
B
Phosalone (35) Aromax/C IX 80/20,70/30 5
771
A
772
B
Phosalone (24)+Cypermethrin (4) Aromax/C IX 80/20,70/30 8
771
A
772
B
Chloropyriphos (20) Mixed Xylene 70/30,60/40 5
771
A
772
B
Chloropyriphos (20) Aromax 30/70,20/80 5
771
A
772
B
Chloropyriphos (20) Aromax/C IX 60/40,50/50 5
771
A
772
B
Fenvalerate (20) Solvent C IX 50/50,40/60 6-7
771
A
772
B
Fenvalerare (20) Xylene 60/40,50/50 6-7.
771
A
772
B
Kitazin (46) Xylene/C IX 80/20,70/30 5
771
A
772
B
Butachlor (50) Kerosene 20/80,10/90 4-5
771
A
772
B
Cypermethrin (10) Solvent C IX 60/40,50/50 6-7
771
A
772
B
Cypermethrin (10) Mixed Xylene 80/20,70/30 6-7
771
A
772
B
Cypermethrin (25) Solvent C IX 50/50,40/60 6-7
771
A
772
B
Cypermethrin (25) Mixed Xylene 70/30,60/40 6-7
771
A
772
B
Alphamethrin (10) Mixed Xylene 60/40,50/50 8
771
A
772
B
Anilophos (30) Aromax/Remax 90/10,80/20 7-8
771
A
772
B
Profenofos (50) Xylene/ C IX 80/20, 70/30, 60/40 5
771
A
772
B
Endosulphan (35) Aromax/ C IX 60/40, 55/45, 50/50 5
771
A
772
B
Lambda Cyhalothrin (2.5) Aromax/ C IX 70/30, 60/40, 55/45, 50/50 8
771
A
772
B
Lambda Cyhalothrin (5.0) Aromax/ C IX 70/30, 60/40, 55/45, 50/50 8
771
A
772
B
Butachlor (50) Kerosene 50/50, 40/60, 35/65 4-5
771
A
772
B
Chloropyriphos (20) Aromax 60/40, 50/50, 40/60 5
771
A
772
B
Ethion (50) Aromax 60/40, 50/50, 40/60 5
771
A
772
B
Malathion (50) Aromax 60/40, 50/50, 40/60 5
771
A
772
B
Trichlopyr Butoxy Ethyl Ester Xylene/C IX 80/20, 70/30, 60/40 10
772
A
772
B
Chloropyriphos (50) +Cypermethrin (5) Solvent C IX 50/50,40/60, 30/70 8
772
A
772
B
Chloropyriphos (50) +Cypermethrin (5) C IX+ Aromax 50/50,40/60 8
772
A
772
B
Chloropyriphos (50) +Cypermethrin (5) Aromax 40/60,30/70 8
603
8
340
9
Propargite Aromax/C IX 60/40, 50/50, 40/60 8
771
A
771
B
Pendimethalin (30) Aromax 80/20, 75/25, 70/30
5-6
771
A
771
B
Phosalone (35) Aromax/C IX 80/20,70/30 5
771
A
771
B
Phosalone (24)+Cypermethrin(4) Aromax/C IX 80/20,70/30 8
771
A
771
B
Chloropyriphos (20) Mixed Xylene 70/30,60/40 5
771
A
771
B
Chloropyriphos (20) Aromax 30/70,20/80 5
771
A
771
B
Chloropyriphos (20) Aromax/C IX 60/40,50/50 5
771
A
771
B
Fenvalerate (20) Solvent C IX 50/50,40/60 6-7
771
A
771
B
Fenvalerate (20) Xylene 60/40,50/50 6-7
771
A
771
B
Kitazin (46) Xylene/C IX 80/20,70/30 5
771
A
771
B
Butachlor (50) Kerosene 20/80,10/90 4-5
771
A
771
B
Cypermethrin (10) Solvent C IX 60/40,50/50 6-7
771
A
771
B
Cypermethrin (10) Mixed Xylene 80/20,70/30 6-7
771
A
771
B
Cypermethrin (25) Solvent C IX 50/50,40/60 6-7
771
A
771
B
Cypermethrin (25) Mixed Xylene 70/30,60/40 6-7
771
A
771
B
Alphamethrin (10) Mixed Xylene 60/40,50/50 8
771
A
771
B
Anilophos (30) Aromax/ C IX 90/10,80/20 7-8
771
A
771
B
Profenofos (50) Xylene/ C IX 80/20, 70/30, 60/40 5
771
A
771
B
Endosulphan (35) Aromax/ C IX 60/40, 55/45, 50/50 5
771
A
771
B
Lambda Cyhalothrin (2.5) Aromax/ C IX 70/30, 60/40, 55/45, 50/50 8
771
A
771
B
Lambda Cyhalothrin (5.0) Aromax/ C IX 70/30, 60/40, 55/45, 50/50 8
771
A
771
C
Butachlor (50) Kerosene 50/50, 40/60, 35/65 4-5
771
A
771
C
Chloropyriphos (20) Aromax 60/40, 50/50, 40/60 5
566 566 Triazophos Xylene / C IX 60/40, 50/50, 40/60 15-17
777
A
777
B
Cypermethrin ( 10 & 25 ) Solvent C IX 80/20,70/30 7 - 8
771
A
771
B
Deltamethrin ( 2.8 ) Solvent C IX 80/20,70/30 6-7
771
A
771
B
Benthiocarb ( 50 ) Kerosene / C IX 70/30,60/40 4 - 5
771
A
771
B
Diazinon ( 20 ) Mixed Xylene 30/70,20/80 5
771
A
771
B
Endosulfan ( 35 ) Aromax/Reemax 60/40,50/50 4 - 5
771
A
771
B
Endosulfan ( 35 ) Solvent C IX
50/50,40/60
4 - 5
771
A
771
B
Fenvalerate ( 20 ) Solvent C IX 60/40,50/50 6-7
771
A
771
B
Heptachlor ( 20 ) Solvent C IX 80/20,70/30 4 - 5
771
A
771
B
Kitazin ( 48 ) Solvent C IX 20/80,10/90 5
771
A
771
B
Metasystox ( 25 ) Xylene/C IX 60/40,50/50 5
771
A
771
B
Quinalphos ( 25 ) Aromax/C IX 80/20,70/30 6 - 8
771
A
771
B
Tetradifon ( 8 ) Solvent C IX 50/50,40/60 5 - 6
771
A
771
B
2,4-D Ethylester(34) Aromax 70/30,60/40 4 - 5
771
A
771
B
Lindane ( 20 ) Aromax/C IX 60/40,50/50 5
771
A
771
B
Lambda Cyhalothrin (2.5) Aromax/C IX 70/30, 60/40, 55/45,50/50 8
771
A
771
B
Lambda Cyhalothrin (5.0) Aromax/C IX 70/30, 60/40, 55/45,50/50 8
771
A
771
B
Hexaconazole (5/10) Mixed Xylene 60/40, 50/50, 40/60 8