Canadian Finishing & Coatings Manufacturing Magazine March/April 2022 - 28

PAINT AND COATINGS MANUFACTURING: PAINT MIXING
not in the pumping system. The new colour was bought to the
pumping system and rushed into production without agitation
of the coating before use. "
" All coatings are a combination of resins, fillers, colourants,
the vehicle for flow control, levelling, etc. This complex blend
of ingredients must be completely mixed before being used.
Most fillers and many colourants are heavier than the solvents
(Solvent or water-based, depending on the type of coating). The
problem was the complex blend of ingredients was not agitated
before use. The heavier ingredients of the coating blend were at
the bottom of the container, so they were being removed during
the first part of production due to the lack of complete agitation.
So, the following day, with most of the heavier parts of the
coating removed the day before, all that was left was coloured
solvent, which provided NO coverage. The fillers and colourants
had been used the preceding day when the coating was rushed
into production without proper agitation. "
" This is a simple story that needs to be followed entirely before
any coating is used- this might be a simple cup gun container,
a pressure tank, a 5-gallon pail, a 55-gallon drum of coating or
even a 300-gallon tote tank; this applies to simple pressure
pots too. Many different coatings are being applied daily, from
pigmented stains to high solids multi-component coatings. The
same applies to every area in liquid finishing.
Many installations only use one colour and one coating.
The same rule applies here too. We have many propane tanks
(20-pound grill propane tanks) finishing systems that leave
the coating in the system. In this case, the supply container
needs to be agitated at least 15 minutes before production, and
the coating MUST be circulated within the pressure system to
remix the complex blend back to a uniform mixture. "
" Many of today's coatings have higher and higher volume
solids which reduce the VOCs from the coating. This mixture
needs to be wholly blended before using. I always recommend
at least 15 minutes of agitation before production starts. And,
as the various volume solids have different weights, agitation
should be continued during all production to ensure a uniform
blend.
And with the newer high solid's coatings, the agitation should
not be done with small high-speed bladed agitators, which can
easily result in foaming of the coating in the supply container.
The best agitators are gear-reduced slow-speed agitators with
LARGE mixing blades. This will keep the coating much more
uniform, which will allow consistent finishing results. "
" In addition, most water-based coatings are thixotropic.
This means as work is imparted into the coating, the viscosity
of the coating will fall to a constant level. So, with the constant
agitation, we are also controlling the viscosity of the coating.
With control of the viscosity, the finishing results are assured. "
" The bottom line is a quality agitator is an important
component of a good finishing system. Without consistent
mixing of the coating, the results will vary. Agitation assures a
uniform coating from the very start of production until the last
part being finished. "
Ross has recently introduced the ROSS X-Series Inline
Ultra-High Shear Mixer, which is intended for emulsification,
https://www.ceresana.com/en/market-studies/industry/paints-coatings-world/
28
www.cfcm.ca
dispersion, and homogenization in various applications.
Designed for use in sanitary and industrial environments, the
Ross X-Series Inline Ultra-High Shear Mixer machine produces
dispersions, suspensions, and emulsions in various industries,
including food processing, cosmetics, and pharmaceuticals
manufacturing. It is also used in the adhesive and composites
manufacturing industries.
Features a type 316 stainless steel mixing chamber, a 150-psig
jacket for cooling and heating up to 250 degrees F, and an X-5
Series 9-in. diameter AL6XN stainless steel rotor/stator that
operates at up to 5700 rpm (13,430 feet per minute tip speed),
the Model HSM-409XSHD-125 is suitable for CIP applications.
Incorporating concentric rows of intermeshing teeth, the
X-Series mix head is a patented design that allows the product
to enter the stator in the centre and flow outward along the
radial channels to the outside edges of the stator. Because of
the combination of extremely tight tolerances and highly high
tip speeds, the product is subjected to enormous shear on each
pass through the rotor/stator. The X-Series consistently delivers
a droplet or agglomerate size reduction compared to typical
colloid mills.
In addition, ROSS Batch High Shear Mixers equipped with the
Solids/Liquid Injection Manifold (SLIM) Technology efficiently
transfer powders for rapid wetting out and complete dispersion
into low-viscosity liquids, allowing for greater productivity.
The ingredients are continuously taken from underneath the
mixing head and subsequently discharged at high velocity via
the stator apertures of a standard rotor/stator mixer (rotor/
stator mixer). With Progressive Spiral Porting, a SLIM mixer
assembly generates a strong vacuum that sucks powders straight
into the high shear zone and quickly disperses individual solid
particles into the liquid vehicle. When the powder is added in
this manner, lumps (fisheyes) are significantly reduced, floating
powders are avoided, dusting is eliminated, and the mixing time
is significantly reduced. The SLIM is a flexible instrument that
may introduce small liquid components and generate delicate
emulsions.
To make it easier to raise and lower the High Shear Mixer
in and out of the mixing vessel, Ross provides a floor-mounted
version that includes an air/oil hydraulic lift system. When the
mixer is in the elevated position or without a mix vessel, safety
limit switches prevent the mixer from being operated.
In essence, manufacturers must take into account the
increasing demand for specialty and high-value-added coatings
while creating their processes. Coatings experts are often
looking for ways to improve efficiency and compliance while
keeping a tight grip on their company's budget. Increasing the
efficiency of a company's mixing processes is a sound business
decision. Conventional products and processes may benefit
from a strategic review of the mixing operation, no matter how
established. There are many dispersion tools used by the paint,
ink, and coating industries, some of which are relatively new
solutions to long-standing processing issues. Viscosity profile,
the necessity for shear, the sequence of addition, and throughput
all play a role in selecting a mixer.
https://www.ceresana.com/en/market-studies/industry/paints-coatings-world/ http://www.cfcm.ca
Canadian Finishing & Coatings Manufacturing Magazine March/April 2022

Table of Contents for the Digital Edition of Canadian Finishing & Coatings Manufacturing Magazine March/April 2022
