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1
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2
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- 1) Color Shift
- 2) Unpredictable results
- 3) Stability issues especially pigmented
- emulsions (W/Si).
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3
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- 1. Treated Pigment
- 2. Emulsifier
- Homogeneous
- Non-homogeneous
- 3. Interactions
- 4. Testing
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4
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- Why Treat?
- Make pigment more hydrophobic
- Make pigment more compatible with oil phase
- Make pigment less likely to agglomerate
- Make emulsion more stable
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5
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- Reacted
- All of these materials are based upon reactive coating materials. These
can include silicones, silanes and free radical products.
- Chemisorbed
- All of these provide coating by physical bonding an oil to a pigment
making it hydrophobic.
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6
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- Transient Coatings
- That is the coating will be removed by emulsifiers over time to result
in the lowest free energy
- The time frame is determined by the nature if the coating
- Can be long time frame
- Accelerated by temperature, emulsifier and overall energetics of the
system.
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7
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- Reacted Coatings
- The reaction of the coating to the surface of the pigment results in improved
permanence of the coating.
- Depends upon the reaction and how well it is run each batch
- QC?
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8
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- A pigment is coated with oleic acid in a ribbon blender. The result is
an organo modified pigment on which the oleic acid is roughly uniform.
- There is no reaction. The oleic acid stays on the pigment simply by
wetting it out and assuming the lowest free energy.
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9
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- The oleic pigment is placed in an invert emulsion along with an
emulsifier, an oil, water and other additives, including thickener.
- Under normal conditions the emulsifier would remove the acid and the
acid would end up in the oil phase, that is the phase in which it is
most stable.
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10
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- Since the formulation is thickened and the emulsion has stability the
whole process is delayed!
- A separation that would normally take minutes to occur could take weeks.
- Heat accelerates the effect.
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11
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- “Bad emulsion”.
- Color Shift
- Coated pigment
- Naked pigment
- Lack of predictability
- Corrective Steps
- Change emulsifier
- Change process for emulsion
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12
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- To the extent the coating process is not correctly run, there can be
batch to batch variation in the pigment and to greater or lesser extent
the problem outlined as example 1 occurs.
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13
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- This problem then is one of randomness in the lack of performance and is
worse in many ways since it is unpredictable batch to batch.
- Drives production and QC people crazy!
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14
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- Get full disclosure
- Reacted or chemosorb
- Type of coating
- QC of coating
- Impose QC Test
- Extraction prior to use
- Require test from vendor as part of QC.
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15
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16
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- A Soxhlet extractor is a type of laboratory glassware invented in 1879
by Franz von Soxhlet. It was originally designed for the extraction of lipid
from a solid test material, but can be used whenever it is difficult to
extract any compound from a solid.
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17
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- Typically, dry test material is placed inside a "thimble" made
from filter paper, which is loaded into the Soxhlet extractor. The
extractor is attached to a flask containing a solvent (commonly diethyl
ether or petroleum ether) and a condenser. The solvent is heated,
causing it to evaporate. The hot solvent vapor travels up to the
condenser, where it cools and drips down onto the test material. The
chamber containing the test material slowly fills with warm solvent
until, when it is almost full, it is emptied by siphon action, back down
to the flask. This cycle may be allowed to repeat many times. During
each cycle, a portion of the lipid dissolves in the solvent. However,
once the lipid reaches the solvent heating flask, it stays there. It
does not participate in the extraction cycle any further. This is the
key advantage of this type of extraction; only clean warm solvent is
used to extract the solid in the thimble. This increases the efficiency
of the extraction when compared with simply heating up the solid in a
flask with the solvent
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18
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19
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- Emulsifiers are complex oligomeric mixtures of products used with a
plethora of other ingredients by the cosmetic chemist in making invert
emulsions.
- Invert emulsions are by far the most complicated single phase emulsion
in personal care line.
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20
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-
CH3
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- CH3 CH3 CH3 (CH2)17 CH3
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- CH3- Si - O - (- Si - O )a- (-Si - O)b
-(- Si - O)c –Si - CH3
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- CH3 CH3 (CH2)3 CH3 CH3
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-
O
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-
(CH2CH2O)x(CH2CH(CH3)O)y(CH2CH2O)zH
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21
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22
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23
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- These materials are used as
emulsifiers in the preparation of both water in silicone and silicone in
water systems. These products provide advantageous over traditional
hydrocarbon chemistries since they can be used in the preparation of
emulsions without heat. These
silicone polymers can be used to
prepare products that contain little wax, contain a large concentration
of water and have a light spreadable feel on the skin.
These products possess a water-soluble, an oil soluble, and a silicone soluble
portion of the molecule, and consequently the 3D HLB concept applies to these materials.
This tool allows for the systematic selection of an emulsifier containing all three parts
in one molecule.
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24
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25
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26
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- Emulsion from R&D is robust giving acceptable product every time
- First few production batches are fine
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27
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- Soon product is not working well.
- Production complaints product is not performing each time
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28
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- Production becomes convinced that R&D has a haunted formula.
- R&D is convinced that production is haunted.
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29
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- It is finally realized that all batches made in the lab were with
pre-warmed one phase emulsifier. (a=2).
- Production batches come in metal drums. Operators do not have X ray
vision. So they do not know if separated material is in the drum.
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30
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- Separation could well happen in the warehouse if it gets cold.
- Problems of a random type.
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31
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- Buy an emulsifier that does not split when cold. (a=5).
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32
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- It is finally realized that all batches made in the lab were with
pre-warmed one phase emulsifier. (a=2).
- Production batches come in metal drums. Operators do not have X ray
vision.
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33
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- Erratic Emulsifier
- Unpredictable Pigment coating
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34
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- Correct one situation at a time.
- Kit Approach
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35
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36
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- 1. Leave out Pigment
- 2. Check Emulsion with different emulsifiers
- 3. Optimize for oil
- 4. Run pigment extraction test
- 5. Put pigment back in
- 6. Re check
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37
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38
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Notes
