New Industrial Mixer - Is Low RPM Homogenizer Possible (for Carbomer)?

CetarCetar Member
I'm looking to purchase 500L mixer for a new production line, and the supplier I'm interested in has a tank with a built in homogenizer (0-3000rpm) and paddle mixer (0-65rpm). However, the technical data sheets for the different Carbopols all boil down to the same thing: high shear mixing damages the end-product viscosity.

So, I'm faced with this question, is it possible to use the tank's homogenizer on a lower setting (800-1200rpm) as to not damage the viscosity of the product, or does it have to obligatorily be the preferred 3-blade marine impeller type outlined in the TDS? Supplier says he can fit a 'low-shear' homogenizer blade (and explosion-proof air paddle motor), but I'm not sure if the small blade of the homogenizer will create the kind of vortex necessary for the carbomer dispersion. Is this equipment overkill?



The final product is a 70% V/V alcohol gel solution, we're using a generic carbomer 940 as thickener, and preferably we have future-proof equipment to pivot to contract manufacturing for different industries if needed in the future. 

Thank you in advance!

Comments

  • BelassiBelassi Member, PCF student
    Just use the paddle blade. Provided you give it enough time, 940 is no problem, but I must admit I wish I could get Ultrez 21.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • alchemist01alchemist01 Member
    edited April 24
    This is what we do in our production of 1000L gel batches:

    1) Add carbomer into a dry vessel
    2) Add water on top, and try to make an effort to wet all the carbomer so that no dry "islands" poke up
    3) Give it a good, low shear mix until homogenous
    4) Store overnight (12+ hrs)

    In the morning a visual QC check confirms hydration and that batch can be used.

  • @alchemist01 What is the rpm of your paddle mixer?
  • @Cetar Is that mixer under vacuum or not? I am just curious
  • @Cetar I have seen that machine design exactly from a Chinese supplier that I am talking with for several days. Is that supplier from Guangzhou?
  • @alchemist01 What is the rpm of your paddle mixer?
    I use a mount mixer that mixes everything in its final container (a 1kL tote), but I would estimate about 150-250rpm for 30 minutes for the carbomer mixing.
  • nielrobertlimnielrobertlim Member
    edited April 25
    @alchemist01 may I know what kind of mixing head did you use for your mount mixer? I am interested to know since I am about to buy 5000L batch of mixer and mixing vessel just to make hand sanitizer
  • ThotaThota Member
    Even I am considering to invest in a all in one vessel to do my emulsions and gels. Previously all my bathces are by Waring Stick Blender and a lab stirrer. 
    Need to Upgrade to a proper indistrial set up. 

    What kind of mixing vessels do u use for small scale production like 100-150kg, specially for beginners in this industry. 

    I cannot invest in 2-3 machinery but need only one for both high shear and low shear and scrapping walls. My supplier is also talking about only 2 mixers- 1 homogeniser and 1 scrapping stirrer low RPM. 

    Any inputs much appreciated!

  • em88em88 Member
    That is a weird position for the homogenizer. 
    The homogenizer does not create a vortex. The fluid flow is perpendicular to the surface. It is very easy to work with carbomer. The homogenizer (if it has enough power) should be able to disperse carbomer in the fluid mass, while the mixing paddle should mix carbomer with the neutralizer and form the gel. You will not need the homogenizer during this phase.  

    @alchemist01, your process needs to be optimized. You are wasting 12 hours. 
  • em88 said:
    The homogenizer (if it has enough power) should be able to disperse carbomer in the fluid mass, while the mixing paddle should mix carbomer with the neutralizer and form the gel. 

    @alchemist01, your process needs to be optimized. You are wasting 12 hours. 
    It's actually quite an efficient process. It's not worth it to me to use a homogenizer and dispense into final containers, as I can hydrate/mix/neutralize the gels in totes and ship them out as is. I would argue that it saves a lot in the long run as far as maintaining and cleaning a mixing tank goes. The 12 hour downtime only costs me a corner in the warehouse where they're stacked.
    I understand my situation is kind of unique, though, so it's hardly a method for everyone. Rather, I was elaborating on how with 940 you don't need high RPM mixing at all, if you invest time. 
  • MedgarMedgar Member
    I actually consider that a Homogenizer is not required to make a Carbopol gel.
    I have made many batches using a homogenizer in different circumstances and in all they lower the viscosity of the carbopol gel
  • MedgarMedgar Member
    If the Carbomer is homogenized to disperse it in the water, the final Carbopol gel loses viscosity.
    If the carbomer is left to humidify for 12 hours and homogenizes after the Gel is formed, this gel also loses viscosity.

    In other words, a carbopol gel should not be homogenized, since neither controlled homogenizations, graduating its time and speed, will in any way affect its viscosity to any degree.
  • CetarCetar Member
    @Cetar Is that mixer under vacuum or not? I am just curious

    @Cetar I have seen that lmachine design exactly from a Chinese supplier that I am talking with for several days. Is that supplier from Guangzhou?
    @nielrobertlim No, this model is not under vacuum, and yes this supplier is from Guangzhou, but names in PM or else their lead times may increase for both of us LOL.

    em88 said:
    That is a weird position for the homogenizer. 
    The homogenizer does not create a vortex. The fluid flow is perpendicular to the surface. It is very easy to work with carbomer. The homogenizer (if it has enough power) should be able to disperse carbomer in the fluid mass, while the mixing paddle should mix carbomer with the neutralizer and form the gel. You will not need the homogenizer during this phase.  
    @em88 Ok that is very helpful, so the carbomer can be dispersed in the water before neutralization, and the paddle can be used during the thickening/neutralization stage. If the carbomer is dispersed with the homogenizer at <1200rpm, wouldn’t the lack of vortex cause all the carbomer to float at the top, stay there, and inevitably lead to unmixed pockets of product (“fish eyes”)?

    Medgar said:
    If the Carbomer is homogenized to disperse it in the water, the final Carbopol gel loses viscosity.
    If the carbomer is left to humidify for 12 hours and homogenizes after the Gel is formed, this gel also loses viscosity.

    In other words, a carbopol gel should not be homogenized, since neither controlled homogenizations, graduating its time and speed, will in any way affect its viscosity to any degree.
    @Medgar At what RPM setting did you come to this result, if you only disperse the carbomer without neutralizing it? Remember the mixer has a homogenizer but since it is adjustable I won’t use it at a high setting, I plan to use it only within the recommended RPM for dispersion <1200rpm.

    Belassi said:
    Just use the paddle blade. Provided you give it enough time, 940 is no problem, but I must admit I wish I could get Ultrez 21.
    @Belassi At 65RPM how long do you think it would it take me for all that 940 to be fully dispersed and hydrated? The paddle alone may be too slow.
  • BelassiBelassi Member, PCF student
    Sorry, but we're not making that kind of batch size, so I am unable to advise.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • MedgarMedgar Member
    I recommend that you standardize your batch of 500 Kg. Each batch size as well as its tools and its procedure is particular for each case.
    What I have mentioned is an experience in the elaboration of a batch of 2500 Kg. In this case, experiments were carried out by rapidly dispersing the carbomer with the homogenizer at 1500 rpm. At this homogenization rate the amount of 0.5% carbomer was ready between 50 min., Using recirculation of the system and with paddle agitation at 500 rpm.
    The consequence of this test is that there is a difference in viscosity loss of the order of 30% compared to laboratory prototypes.

    PS: Sorry Google for any misinterpretation of words.
  • em88em88 Member
    Cetar said:
    @em88 Ok that is very helpful, so the carbomer can be dispersed in the water before neutralization, and the paddle can be used during the thickening/neutralization stage. If the carbomer is dispersed with the homogenizer at <1200rpm, wouldn’t the lack of vortex cause all the carbomer to float at the top, stay there, and inevitably lead to unmixed pockets of product (“fish eyes”)?
    Yes! It depends a lot on the vessel shape, homogenizer position, and homogenizer power. Usually, these issues are taken into consideration if the engineering of the equipment is done correctly. We have 2 industrial lines from different manufacturers. in one we had the issue you mentioned above, so we have to disperse the carbomer in less solvent and than add the rest of it. 
    During the dispersion of carbomer, you should use the paddle as well and at a higher speed than usual, just to help the homogenizer. 
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