Advanced Water Based Dispersants

Advanced Water Based Dispersants
Xyndisp XX101D & Xyndisp XA168D
Xyndisp XX101D
Hyper-dispersant for stable, high scrub paints
Introduction
The role of a dispersant in a decorative paint formulation is to disperse pigment effectively, creating a
stable mill base which can then be let down with binder and other wet ingredients. The stability of the
paint is also affected by other factors such as the effective water hardness, derived from incorporated
water but also from calcium present in the fillers. An uneven distribution can result in reduced gloss
and scrub performance.
In hard water areas polyphosphates are sometimes employed to improve paint stability. However
calcium and other ions present in fillers are also a cause of flocculation; they reduce paint performance
even when mechanical instability is not apparent.
Xyndisp XX101D has been developed in order to improve pigment dispersion stability and in
particular scrub performance. Polyphosphates, where employed can be eliminated, further boosting
scrub performance. In exterior paints, fungal resistance is improved, since polyphosphates are a fungal
nutrient.
Performance of Xyndisp XX101D
Xyndisp XX101D disperses and stabilises pigments more effectively than conventional dispersants,
leading to enhanced binder performance.
• Scrub performance is improved allowing reduction in binder content.
• Where employed the use of polyphosphates can be eliminated, further
boosting performance.
• In exterior coatings, elimination of polyphosphates reduces tendency
for fungal growth.
Often polyphosphates such as Calgon are used to improve stability. However, these additives also
reduce scrub performance markedly. To demonstrate this we took the following model formulations A
and B and measured scrub performance:
Component
Water
Model ‘A’
no Calgon
Model ‘B’
with Calgon
40.77
40.57
Sodium Polyphosphate
---
0.20
Wekcelo HEC 30000B
0.50
0.50
Xyndisp XX101D
0.23
0.23
Preventol BM5
0.20
0.20
Preventol A 24
0.20
0.20
Defoamer
0.15
0.15
Ammonia at 25%
0.20
0.20
Ti-Pure R 931
7.00
7.00
PoleStar 200 P
5.00
5.00
Alusil ET
2.00
2.00
Omyacarb 2 Extra
18.00
18.00
Omyacarb 5 Extra
17.00
17.00
Xynpol VO504L
8.00
8.00
Defoamer
0.15
0.15
Xyntrol DBE-B
0.60
0.60
100.00
100.00
310
180
Total
Scrub performance
- cycles to failure
The effect of polyphosphate on
scrub performance is evident.
This allows the paint formulator
to reduce binder content,
alternatively to consider more
cost effective binder systems.
Note: it is also shown below
that Xyndisp XX101D improves
paint performance in paints
where polyphosphate is not
present.
Elimination of Calgon improves binding performance however in paints made using conventional
dispersants in-can stability is often reduced. In-can stability can be unpredictable; even when paints
exhibit viscosity stability on extended storage, other properties such as localized pigment flocculation,
binding power and gloss development can be adversely affected by hard water or calcium- containing
fillers. Paints made using Xyndisp XX101D display none of these disadvantages as the following study
shows.
Xyndisp XX101D is an advanced hyper-dispersant system containing additional functional groups
that provide pigment stability in paint formulations even at high calcium loading, boosting scrub
performance and avoiding the need for polyphosphates. To demonstrate this effect we have designed
high scrub paint formulations and compared them with paints made using conventional dispersants.
Below is a study to produce an EN13300 Class 3 paint system using a VA/Veova, Xynpol VO504L, a high
binding VA/VV system for interior/exterior paints.
Calgon-free formulations
comparing dispersants
XYN2026 ‘C’
no Calgon
XYN2026 ‘D’
no Calgon
Water
35.40
35.40
Dispex N40
0.25
---
Component
Xyndisp XX101D
---
0.25
Acticide MBS 50/50
0.20
0.20
Wallocel XM 6.000 PV
0.50
0.50
Xynburst 9615
0.10
0.10
Tiona 595 / Tipure R706
6.50
6.50
Omyacarb 2GU lose
18.50
18.50
Dorkafill Pro Void
8.50
8.50
Celite 388
1.60
1.60
Intalk 20LA
8.50
8.50
Precarb 100
10.00
10.00
Dorsilit 2500
1.60
1.60
Sodium hydroxide solution 10%
0.05
0.05
Xynburst 9615
0.10
0.10
Waxmull WM 120
1.00
1.00
Xynpol VO504L
7.00
7.00
Xynpol AX200R
0.20
0.20
100.00
100.00
XYN2026 ‘C’
no Calgon
XYN2026 ‘D’
no Calgon
The performance results are summarised in the
table below; we carried out in-can stability tests
over 28 days and also tested paints to EN 13300.
EN 13300 loss (µm)
In-can stability 1 day
Xyndisp In-can stability 28 days
35.3*
17.8
Free flowing
Free flowing
Excessive thickening!
Free flowing
* Measured on paints applied before instability is apparent.
Paint XYN2026C, produced using conventional dispersant exhibited excessive thickening over 28
days and would not flow from the can. Paint D produced using Xyndisp XX101D remained stable and
free-flowing. Paint XYN2026D passes EN13300 class 2. It is interesting that in this system scrubs were
also improved while maintaining paint stability. This improved scrub resistance using XX101D was
seen with a number of binders. In all cases paints produced from conventional dispersant went on to
partially coagulate after 28 days but were stable when Xyndisp XX101D was used.
Discussion
Xyndisp XX101D produces stable, high performance paints. Scrubs are boosted and if polyphosphate
is part of the standard formulation it can be eliminated, further boosting performance. The paint
formulator can exploit the improvement in scrub performance by reducing binder levels; alternatively
he might incorporate alternative cost effective binders.
There is also evidence that the use of polyphosphates in paint films increases the tendency for fungal
growth, therefore its elimination will lead to improved anti-fungal performance.
Further work
We have carried out further work on class 2, 3 and 4 paints using a variety of binders. All were stable
with the addition of Xyndisp XX101D, indicating that we have a robust system.
These formulations are unstable with conventional dispersant and furthermore do not perform well if
polyphosphate is added. Note that we were able to reduce the dispersant content and still maintain
high performing, stable systems:
Start Formulation XYN2027
Start Formulation XYN2028
Start Formulation XYN2029
EN13300 Class 2 Scrub-resistance
EN13300 Class 3 Scrub-resistance
EN13300 Class 4 Scrub resistance
(According to EN 13300 – Class 2:
≥ 5 μm and < 20 μm at 200 Scrubs).
(According to EN 13300 – Class 3:
≥ 20 μm and < 70 μm at 200 Scrubs).
(According to EN 13300 – Class 4:
< 70 μm at 40 Scrubs).
Component
Weight
MIX
Water
Component
Weight
MIX
351.80
Water
Component
Weight
MIX
344.70
Water
397.50
Xynburst 9615
2.00
Xynburst 9615
2.00
Xynburst 9615
2.00
Xyndisp XX101D
3.00
Xyndisp XX101D
3.00
Xyndisp XX101D
3.00
Acticide
2.00
Acticide
2.00
Acticide
2.00
Wallocel XM 6.000 PV
5.00
Wallocel XM 30.000 PV
3.80
Wallocel XM 30.000 PV
5.00
DISPERSE
DISPERSE
DISPERSE
Tipure R706
190.00
Tipure R706
80.00
Tipure R706
40.00
CaCO3 2 μm
85.00
CaCO3 2 μm
100.00
CaCO3 2 μm
200.00
Intalc 20LA
85.00
Intalc 20LA
110.00
CaCO3 10 μm
180.00
Sipernat P 820
40.00
Chalk T60
85.00
Chalk
65.00
Dorkafill H
65.00
Precarb 100
110.00
Talcum ST60
65.00
Mica Celia 100L
60.00
Mica Celia 100L
80.00
Sodium Hydroxide 10%
0.50
Sodium Hydroxide 10%
0.50
Sodium Hydroxide 10%
0.50
MIX
MIX
MIX
Xynburst 9615
1.00
Xynburst 9615
1.00
Xynburst 9615
1.00
WaxMul WM 110
6.00
Coapur 830W
1.70
WaxMul WM 110
6.00
Xynpol SA510L
30.00
WaxMul WM 110
6.00
Xynpol VO504L
70.00
Xynpol AX200R
Xynpol VO504L
100.00
Xynpol AX200R
2.00
Total
Xynpol AX200R
Total
Non Volatile Content:
pH:
PVC:
2.00
Total
3.00
1000.00
1000.00
1000.00
59.0%
8.0
52.5%
Non Volatile Content:
pH:
PVC:
61.3%
8.0
56.5%
Non Volatile Content:
pH:
PVC:
57.6%
8.0
55.0%
Xyndisp XA168D
Advanced dispersant for ceramic slurries and mill bases
Xyndisp XX101D described above, is a modified polyacrylic acid dispersant. Its performance is
largely electrostatic aided by other functional groups; negatively charged particles accumulate on the
surface of the fillers which then disperse by repulsion.
Xyndisp XA168D is designed to disperse solids in suspension using a combination of electrostatic
repulsion and steric hindrance, as illustrated in figure 1 below.
Figure 1a:
Dispersion controlled by electrostatic repulsion
Figure 1b:
Dispersion controlled by steric hindrance
Xyndisp XA168D has been designed for use in the ceramics industry, where a wide variety of
aggressive solids are used. Often these are subjected to severe and sustained processes including
pumping, recirculation (often at elevated temperature), as well as spray drying. Mechanical stability
needs to be maintained during these conditions. In addition the viscosity of ceramic slurries needs to
be optimized. This is particularly relevant to spray drying where the effective capacity of the dryer and
the energy cost of the process are both solids-dependent.
Xyndisp XA168D is a water- based, ammonia free, low sodium system based on in house monomer
technology. It offers outstanding performance in ceramic and other filler systems.
Brookfield Visc. (mPa.s)
Viscosity reduction Titanium Dioxide
14000
12000
Xyndisp XA168D
10000
8000
6000
4000
2000
0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
% Dispersant on Filler
1.6
1.8
2.0
The two scanning electron micrographs (SEMs) below show proprietary ceramic slurries, following a
spray drying procedure. The left hand slide is produced with a conventional dispersant. The right hand
slide is the same formulation produced using Xyndisp XA168D. The improved quality of the ceramic
particles is evident. It has also been demonstrated that up to 45% water reduction is achievable to
produce slurry of equal viscosity and mechanical stability.
SEM conventional dispersant
SEM Xyndisp XA168D
200 micron
Comparing micrographs of the two slurries, clear improvement in the sphericity of the spray dried
granules is observed with Xyndisp XA168D. Particles are also found to be much less porous on both a
macroscopic and microscopic level when Xyndisp XA168D is used. An increase to slurry solids content
allows improved efficiency for the spray drying operation, greatly reducing energy consumption.
Advantages of Xyndisp XA168D in water based ceramic slurries:
•
•
•
•
•
•
Higher solids at low viscosity
No added sodium
No ammonia smell or volatility
Higher energy efficiency, big spray drier savings
Increased water resistance from lower dispersant demand
Lower transport costs when shipping slurries
Applications for Xyndisp XA168D include:
•
•
•
•
•
Hi tech ceramic slurries and paints
High solids water based coatings
Water resistant coatings
Efficient shipment of high mill bases and slurry intermediates
Paper industry
For further information please contact our Technical Service Department or refer to www.xyntra.com
Registered Office and main contact
Xyntra Chemicals B.V.
Achterdijk 13 E
NL-5705 CB Helmond
The Netherlands
Main Production site
Resiquimica S.A.
Rua Francisco Lyon de Castro, 28
2725-397 MEM MARTINS
Portugal
T: +31 492-59 75 70
F: +31 492-59 08 12
www.xyntra.com
info@xyntra.com