Background/Requirement
Carbomers and Polymers have been in use as rheology modifiers
or structure building agents in a wide variety of applications
including Personal Care, Pharmaceutical, Home Care and Industrial
products because of their exceptional thickening, stabilizing
and suspending properties. They provide the flexibility to
develop products with a wide range of flow and rheological
properties. These polymers are typically supplied in a powdered
form and when added to liquids are capable of creating extremely
high molecular weight polymers at concentrations below 2%.
They are ideal for the Personal Care and Pharmaceutical industry
as they demonstrate a low toxic and irritation potential.
Manufacturers have often raised concerns regarding the long
mixing cycles and difficulty in dispersing hydrophilic polymers
in water with-out "fish-eyes" or agglomerates. "Fish-eyes"
are lumps of product with a hydrated skin but an unhydrated
dry core. They are created when a hydrophilic powder comes
in contact with water, the particles on the surfaces hydrate
and crosslink to form a tough outer layer and the particles
on the interior cannot be hydrated because they are shielded
from the water. The following problems can be encountered
when using in-tank technology to disperse Carbomers and Polymers:
| • |
Do not produce sufficient shear to reduce particle size
and eliminate "fish-eyes" or agglomerates. |
| • |
Long mixing cycles are required to obtain uniform dispersion
and to complete hydration. |
| • |
As the solution viscosity increases, agitation of the solution
and powder dispersion becomes increasingly more difficult. |
| • |
Powders will raft, surface turbulence generated is not normally
sufficient to draw in the powders. |
| • |
Most of the polymers have pseudo-plastic or thixotropic properties.
Over-processing to eliminate lumps reduces the effective viscosity,
forcing the processor to compensate with the addition of additional
ingredients. |
| • |
At the end of the batch a significant amount of dry material
must then be removed through filtering. |
Quadro's Approach
The ZC Inline Powder Disperser is designed specifically
to disperse extremely difficult-to-wet powders such
as Polymers and Carbomers, into a liquid stream in a
single pass. Powder incorporation is achieved by the
presence of significant vacuum in the reactor housing
generated by the liquid seal created between the rotor
and stator. This vacuum ensures that powders from the
hopper above are drawn into the reactor head, where
the particles are subjected to intense mechanical shearing
PRIOR to hydration into the liquid stream. The result
is a perfectly dispersed and homogeneous dispersion
of hydrophilic powders WITHOUT "fish-eyes".
Typical In-line Setup
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