HEC (hydroxyethylcellulose) dissolution problem

Tagged: advanced, cloudy-solution, hec

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HEC (hydroxyethylcellulose) dissolution problem

Posted by filiz on July 30, 2021 at 8:18 am

I am working on a roll-on formulation and I am using HEC as a thickener at 0.9% in nothing but both at cold and warm water (50 ‘C) but I couldn’t dissolve it. I mixed it with mechanical stirrer at 500 rpm sometimes even more. Is it beacause my chemicals or my methode ? I used two different HEC but ı couldn’t dissolve both anyway. To conclude if you have any suggestions I would be so glad, thanks in advance.

ketchito replied 2 years, 8 months ago 4 Members · 10 Replies
10 Replies

ketchito

Member
July 30, 2021 at 3:36 pm

@filiz You need to slowly add the HEC directly to the vortex formed during mixing at moderate-high speed. I’d go at 1000 rpm or even more, and leave it mixing for at leat 10 min. One thing that improves mixing is adding some base (eg., Sodium hydroxide, TEA), to help dissolve the outer shell that recovers polymer particles.
oldperry

Member
July 30, 2021 at 6:01 pm

And cold water is preferred.
filiz

Member
August 2, 2021 at 2:40 pm

Thank you for your advices. Increasing pH realy works with cold water, I go with 1000 rpm for a hour, nevertheless I couldn’t completely dissolve HEC. If you have any other solutions I would be so glad…
paprik

Member
August 2, 2021 at 6:59 pm

Hi,

you can add HEC straight into cold water and either high shear it for a prolong time or neutralise (alkaline) it to pH>7. Once fully hydrated, you can bring the pH lower again.

Hope that helps.
ketchito

Member
August 3, 2021 at 1:32 pm

@filiz Add first the HEC with high mixing. Mix for 5 minutes, and only then, increase the pH (Sodium hydroxide works well, but use only a little amount -don’t stop mixing while adding it-).
filiz

Member
August 10, 2021 at 5:11 am

@Paprik
@ketchito
thanks for your help.. Mixing high level and adjusting to neutralise has worked but the image i get is blurry even though it was mixed for 2 hours. What do you think?
filiz

Member
August 10, 2021 at 5:38 am

Obsevation:
1. Aqua + Hydroxyethyl Cellulose (%2) + TEA (Opaque white, fairly solid)
2. Monoprpylene Glycol (4,5) + Alcohol (%20) (transparet but bullry)
ketchito

Member
August 10, 2021 at 4:14 pm

@filiz Could you switch from TEA to Sodium Hydroxide, to see if it improves? Also, any chance the turbidity might be caused by bubbles (since you’re adding high levels of HEC, viscosity might make bubbles formed during mixing, hard to be released).
filiz

Member
August 11, 2021 at 5:49 am

@ketchito
What do you think the ideal amount of HEC should be? And should I keep the rpm low to avoid bubbles?
ketchito

Member
August 11, 2021 at 12:52 pm

@filiz I used to have few issues with HEC back in the day, and I found out some literature. Perhaps this one could help you: http://doorirng.com/data/Personel%20care%20cellosize.pdf.

There is a method in that brochure that includes heating, and that could help get rid of the bubbles. Good luck!