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 Model A Model B with Calgon Water 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 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. Total 100.00 100.00 Scrub performance - cycles to failure 310 180 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 Component XYN2026 C XYN2026 D Water 35.40 35.40 Dispex N40 0.25 --- 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 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. XYN2026 C XYN2026 D EN 13300 loss (µm) 35.3* 17.8 In-can stability 1 day Free flowing Free flowing Xyndisp In-can stability 28 days 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 EN13300 Class 2 Scrub-resistance Start Formulation XYN2028 EN13300 Class 3 Scrub-resistance Start Formulation XYN2029 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 Component Weight Component Weight Water 351.80 Xynburst 9615 2.00 Xyndisp XX101D 3.00 Acticide 2.00 Wallocel XM 6.000 PV 5.00 DISPERSE Tipure R706 190.00 CaCO3 2 μm 85.00 Intalc 20LA 85.00 Sipernat P 820 40.00 Dorkafill H 65.00 Mica Celia 100L 60.00 Sodium Hydroxide 10% 0.50 Xynburst 9615 1.00 Coapur 830W 1.70 WaxMul WM 110 6.00 Xynpol VO504L 100.00 Xynpol AX200R 2.00 Total 1000.00 Water 344.70 Xynburst 9615 2.00 Xyndisp XX101D 3.00 Acticide 2.00 Wallocel XM 30.000 PV 3.80 DISPERSE Tipure R706 80.00 CaCO3 2 μm 100.00 Intalc 20LA 110.00 Chalk T60 85.00 Precarb 100 110.00 Mica Celia 100L 80.00 Sodium Hydroxide 10% 0.50 Xynburst 9615 1.00 WaxMul WM 110 6.00 Xynpol VO504L 70.00 Xynpol AX200R 2.00 Total 1000.00 Water 397.50 Xynburst 9615 2.00 Xyndisp XX101D 3.00 Acticide 2.00 Wallocel XM 30.000 PV 5.00 DISPERSE Tipure R706 40.00 CaCO3 2 μm 200.00 CaCO3 10 μm 180.00 Chalk 65.00 Talcum ST60 65.00 Sodium Hydroxide 10% 0.50 Xynburst 9615 1.00 WaxMul WM 110 6.00 Xynpol SA510L 30.00 Xynpol AX200R 3.00 Total 1000.00 Non Volatile Content: 59.0% ph: 8.0 PVC: 52.5% Non Volatile Content: 61.3% ph: 8.0 PVC: 56.5% Non Volatile Content: 57.6% ph: 8.0 PVC: 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. Viscosity reduction Titanium Dioxide Brookfield Visc. (mpa.s) 14000 12000 10000 8000 6000 4000 2000 Xyndisp XA168D 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 % Dispersant on Filler
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 T: +31 492-59 75 70 F: +31 492-59 08 12 Main Production site Resiquimica S.A. Rua Francisco Lyon de Castro, 28 2725-397 MEM MARTINS Portugal www.xyntra.com info@xyntra.com