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  Neutralization of Carbomer 940

  Posted by MurtazaHakim on November 6, 2020 at 9:07 am

  Dear All,

  I hope everyone is safe and protected during this pandemic. My query as the title suggests is related to neutralization of carbomer 940. I am using 73% v/v of Ethanol 96% and 0.3% w/v of carbomer 940. How much triethanolamine 99% would be required to neutralize it to pH 6-7. I have tried with 0.5 grams per liter of finished product but I think the viscosity can be further increased by adding more. Glycerol is 0.08% w/v.

  Your valuable comments are awaited.

  Fekher replied 4 years ago 3 Members · 2 Replies
• 2 Replies

• 

  Benz3ne

  Member

  November 6, 2020 at 10:17 am

  Triethanolamine, I have found, struggles a little with hydroalcoholic gels towards 70%, so 73% will likely be a little unpredictable.
  I’ve found for 0.3% carbomer 940 that approximately 0.27% aminomethyl propanol does a good job of bringing the pH down to around 6-7.
  This .pdf states ratios but doesn’t touch on maximum ethanol concentrations (page 2, table 1) https://www.lubrizol.com/-/media/Lubrizol/Life-Sciences/Documents/Literature/Bulletin-05—Neutralization-Procedures.pdf

  Be mindful that you’re asking two separate questions. You’ve asked (a) how much TEA is required for pH6-7 and (b) please confirm that adding more TEA will increase viscosity.
  TEA isn’t the thickener, the carbomer is as I’m sure you already know. Neutralising the carbomer is what increases the viscosity, so if you want greater viscosity, you need more carbomer and to then neutralise that. 940 imparts a large viscosity at small concentrations, so note that small changes can make a large difference.

  Hope you are safe and well also.

  Edit: 0.5g per L of product is around 0.0625% TEA (given 70% ethanol solns are approx 0.8g/mL). That won’t be enough to neutralise the carbomer completely. Try focusing on the w/w% of the TEA you’re adding. There’s usually a reasonably wide ‘shelf’ of neutralisation so pH will only jump up after the carbomer is neutralised. 

• 

  Fekher

  Member

  November 6, 2020 at 10:30 am

  @MurtazaHakim the rule is needed TEA equal 1,5 carbomer(in massic level) to neurtalize it and get pH =7 [ the amount can be less or more depends on desired ph] , however for your system which have more then 60 % Ethanol you will need as neutralizer AMP or other neutralizer that can work for your level of alcohol . 

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