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ANIONIC EMULSIONS

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BEESWAX-BORAX. Galen 200 AD- rose water in molten one part beeswax, 3-4 parts olive oil ... 5-7% wt beeswax = wt borax. TEA-STEARATE. Stearic acid CH3(CH2)16COOH ... – PowerPoint PPT presentation

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Title: ANIONIC EMULSIONS


1
ANIONIC EMULSIONS
  • FDU Lab
  • Feb 4, 2008

2
EMULSIFIERS
  • Anionic
  • Nonionic
  • Cationic
  • Steric

3
ANIONIC
CATIONIC
4
AMPHOTERIC
-

-

Higher-anionic
Lower-cationic
pH
5
NONIONIC
Fatty Chain
Ethylene oxide
CH2 CH2 O
-CH2-CH2-O-
N
N
6
STERIC
Example- Pemulen- Breaks with salt
7
HOW STEARIC SOAPS WORK
  • Ionic repulsion-electrical double layer
  • Stearic tail in oil droplet
  • Ionic heads in continuous water phase
  • Ionic heads negatively charged, attract positive
    ions from water phase
  • Double layer repels other dispersed droplets

8
BASIC EMULSION
80 Water 20 Oil 10-15 Oil
phase as emulsifier
9
IN SITU
For the common anionics, we add the fatty acid
and base to make the emulsifier.
10
BEESWAX-BORAX
  • Galen 200 AD- rose water in molten one part
    beeswax, 3-4 parts olive oil
  • 1884- addition of borax to form sodium salt with
    free fatty acids
  • Mineral oil to prevent rancidity by 1905
  • Cerotic C25H31COOH key FA

11
BASIC FORMULATION
13.5-14.5 of beeswax is free acid Guideline 5-7
wt beeswax wt borax
12
TEA-STEARATE
Stearic acid CH3(CH2)16COOH Triethanolamine
(TEA) N(CH2CH2OH)3 TEA-Stearate is salt
13
TYPICAL CREAM FORMULA
  • 15 triple pressed stearic acid
  • 1 KOH (80)
  • 15 polyol
  • 2 isopropyl myristate
  • Qs water

14
POLYOLS
  • Propylene glycol- driest feel
  • Sorbitol and ethoxylated sorbitol-medium feel
  • Glycerin-wettest feel
  • Use level 5-15

15
STEARIC/PALMITIC
Ratio of stearic to palmitic effects viscosity
and appearance of creams
  • Stearic/palmitic 75/25 to 50/50 gives best
    results
  • Highest level stearic give most pearl but softest
    consistency

16
STEARIC ACID SPECS
Emersol 132 NF
17
ANALYTICAL DEFINITIONS
AV mg KOH to neutralize 1 gm fatty acid Eq. Wt.
Contains 1 atomic weight H2 (acid) Iodine
measure of unsaturation Saponification value mg
KOH to hydrolyze 1 gm ester (1 hour reflux)
SV AV Ester
18
(No Transcript)
19
NEUTRALIZATION
AV X Eq. Wt. Base gm base 56.1
1000 gm acid
AV stearic acid 210 Eq. Wt. TEA
149
210 X 149 0.556 56.1 1000
20
pH TEA STEARATE
Exactly neutralized TEA-Stearate will have a very
high pH like any soap. An excess of stearic acid
will bring the pH down to a skin-friendly level.
21
ALKALIES
  • Sodium soaps make hard creams with poor sheen
  • Potassium soaps make soft creams with good sheen
  • Amides make soft creams with excellent sheen, but
    fear of nitrosamines
  • Ammonia has bad odor

22
SOME GOOD MIXES
  • 1/9 NaOH/KOH
  • 1/10 NaOH/KOH good texture, body, sheen
  • TEA with NaOH, KOH or borax

23
SOME ADVANTAGES
  • Low cost
  • Reliable
  • Familiar

24
DISADVANTAGES
  • Irritation
  • Crusting
  • Poor freeze-thaw stability
  • Some darkening over time (especially with TEA)

25
STABILITY
  • 25C one year
  • 37C six months
  • 45C three months
  • 50C one month
  • 4C one year
  • -20C one month

Reaction rate doubles for every 10C rise in
temperature. Assume RT is 25C. BUT this is
an oversimplification!
26
CYCLING
  • -20 TO 25C
  • -20 to 45C (dont return to room temperature)

27
FORMULATING SKIN CARE EMULSIONS
  • Target population
  • Packaging
  • Target cost of goods
  • Product Claims
  • Market leader
  • Stability testing
  • Choosing ingredients

28
IMPROVING EMULSION STABILITY
  • Preservation
  • Package
  • Thicken external phase
  • Phase inversion
  • Mixing temperature
  • Mixing mechanics
  • Cooling

29
Next week HLB and Nonionic Emulsions
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