Densurf DA 4010's Distinctive Impact in Dispersion

Dispersion Effect of Densurf DA 4010 Black is not actually a color, but rather the absence of color that occurs when light striking a surface is not reflected. So how is black color obtained? In nature, it can be derived from the roots, bark, and fruits of walnut, chestnut, and certain oak trees. Artificially, pigments such as iron oxide and carbon black serve as black color sources. Today, carbon black is the most commonly used pigment for obtaining black color. Carbon black is preferred not only for its coloring properties, but also for its characteristics such as absorbing solar radiation, UV resistance, and heat resistance. Industries where it is widely used include the rubber industry, paints and coatings, inks, leather industry, plastics, and textiles. Carbon black production is based on a thermal decomposition (pyrolytic) process of hydrocarbons or vegetable oils. Depending on the production process, properties of carbon black such as color strength, particle size, surface area, and pH can be adjusted. The chemical structure of the carbon black pigment is shown in Figure 1. The structure of carbon black contains functional groups such as ketone, hydroxyl, quinone, lactone, pyrone, and carboxylic acid, and has a hydrophobic surface. The interaction of functional groups present in its chemical structure and the small particle size (typically 20-30 nm) cause agglomeration (flocculation) in liquid systems. Dispersion refers to the separation of powder particles agglomerated in a liquid so that a new interface is created between the liquid surface and the surface of the particles. The dispersion process is an important step in the paints and coatings industry. To disperse carbon black pigment within a liquid system, polymeric dispersing agents are used. Pigment dispersion is achieved through steric hindrance and electrostatic effects in the dispersing agent structure. Densurf DA 4010 is a polymeric dispersing agent. The anchor groups in the structure of the Densurf DA 4010 polymer wrap around the pigment while the tail portion of the polymer provides steric hindrance. In this way, it prevents an increase in system viscosity and maintains stability. Figure 2 shows a schematic of carbon black dispersion with Densurf DA 4010. The tail length of the polymeric dispersing agent prevents interaction between pigments, but the interaction within itself must also be considered. The tail length of the polymer should be at optimum length to prevent pigment interaction while also preventing self-interaction. Figure 3 shows schematically the self-interaction when the polymeric tail length increases. Carbon black, organic pigments, and inorganic pigments are used in universal resin systems. When Densurf DA 4010 was synthesized, the 6-sigma methodology was utilized to determine optimally through experimental design both the acid/amine number of the polymer, the design of anchor groups, and the tail length. In the dispersion process, the amount of dispersing agent is as important as its selection. When the dispersing agent that wraps around the pigment and disperses it in the liquid system is used in excess, the interaction of the groups wrapping the pigment with each other prevents system stability and causes problems such as settling and agglomeration. When the dispersing agent is used in insufficient quantity, it cannot adequately wrap around the pigment and causes the same problems again. When determining the amount of dispersing agent, the calculation of % s.o.p. (solid on pigment) can be used. This ratio varies for each pigment. Much lower ratios are used for inorganic pigments, while higher ratios are used for organic pigments and carbon black. The optimum amount can be roughly calculated by dividing the pigment's surface area by 5. Figure 4 shows the effect of the optimum amount of dispersing agent on the viscosity of the system. For carbon black, the %s.o.p. ratio varies between 30-100% depending on the paint formulation and the surface area of the pigment. % s.o.p.= (solid amount of dispersing agent / pigment amount) *100 To determine the optimum s.o.p. ratio, ratio studies should be conducted in the premix formulation. A solvent-based paint formulation for Densurf DA 4010 dispersing agent is given in Table 1. [caption id="attachment_142675" align="aligncenter"] Table 1. Solvent-based paint formulation for Densurf DA 4010[/caption] Premix samples prepared according to the formulation in Table 1 were tested for initial grinding fineness, viscosity, rub-out testing, and gloss measurements. All samples were kept in a 50°C oven for 2 weeks and viscosity controls were performed with no increase in viscosity observed. After 4 weeks, all tests were repeated and all results were consistent. Viscosity results are shown in Figure 5, gloss measurement results in Figure 6, and rub-out results in Figure 7. References https://www.anatoliakimya.net/Tr/temel-kimyasallar/karbon-siyahi-4567.aspx https://densurf.com/media/rhkdarck/leaflet-da-4010.pdf https://www.orioncarbons.com/en/oec_3065_r7_carbon_black_pigments_tech_data_v2_5_10_19.pdf https://en.wikipedia.org/wiki/Carbon_black Aylin Aydemir Senior Application Specialist Densurf Hüseyin Eren Research and Development Specialist Denge Kimya