Home Cosmetic Science Talk Formulating working with PBSA

  • working with PBSA

    Posted by Mmb11 on July 3, 2024 at 6:47 am

    Hi, I’m trying to formulate a day cream with SPF50+ that has a more day-cream-like texture than sunscreen… So I am trying to include PBSA in order to reduce the greasyness of the formula as I am working with the BASF simulator to quantify the filters (I have no chance of additional testing until the formula is finished) . The thing is I am being asked for a jar-packed-formula and I can´t seem to stabilize or thicken any formula containing PBSA. I’ve found that ExpertGel® EG412 works better than Pemulen TR-1 polymer but still cant find the proper ratio. I also need for the cream to be whitish (if possible), no nano (not even organic filters), no octocrylene, no homosalate, no silicones (if possible), no PEGs…. A mindbreaker.

    It would also be helpful if someone has noticed any ingredient incompatibilities (preservatives, other filters…) or seen if it is possible to work in w/o formulas with this filter…

    Any advice would be grateful.

    Thanks!!

    chemist-chef replied 6 days, 16 hours ago 3 Members · 3 Replies
  • 3 Replies
  • chemicalmatt

    Member
    July 3, 2024 at 1:46 pm

    There is a disconnect here: are you formulating a w/o sunscreen emulsion here? If so, I don’t expect any of the rheology modifiers you mention to work well if at all. Neither the urethane (ExpertGel) nor the acrylic (Pemulen) will build viscosity. Both must have a carbomer partnered with it to build viscosity so just add 0.50 - 1.0% Synthalen K (carbomer) with Pemulen TR-2 - which handles up to 40% oil load, twice that of TR-1 - and make this an o/w emulsion. Add 1.0 - 2.0% cetyl alcohol and some silky sensorial esters and you are done. PBSA is totally compatible with the anionic acrylics.

    • Mmb11

      Member
      July 3, 2024 at 1:55 pm

      No, I was actually working on a O/W, I will try the tips you suggested and see how it goes. The W/O was another option I was considering in order to try and build thickness, but I was just curious if it would work with PBSA as I haven’t seen any market references containing this filter in those type of emulsions.

      Thank you for the tips!

  • chemist-chef

    Member
    July 11, 2024 at 4:54 am

    Hi..

    Since PBSA is an acid, you need to neutralize it to pH around 6-7, until all PBSA are dissolved. You can use AMP95 or TEA to neutralize PBSA.

    This neutralization (Acid + Base), creates a salt, that we all know that salts are usually electrolytes. First thing you need to do is find thickener/polymer and also emulsifiers that resistant to electrolyte so you can thicken your formula. Example for electrolyte-resistant polymer is Sepimax Zen, but if you want to have powerful electrolyte-resistance polymers, you can combine Sepimax Zen with Solagum Tara. Both are supplied by Seppic. And for emulsifiers, you can try Montanov 82.

    If you want to make O/W cream, you can combine those polymers and add some wax to help improve the viscosity of your formulation. You can use Cetyl alcohol.

    If you want to achieve SPF 50, i’m not sure you can achieve it only with PBSA. Usually need to combine it with other UV filter.

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