Filler Ratios in Heat-Resistant Paint Formulation

The Effect of Filler Ratios in Heat-Resistant Paint Formulation As human population increases, new needs emerge. As technology develops, the expected properties of tools or items required increase. Thermal resistance has become an important characteristic across all areas, from simple household items such as ovens, stoves or industrial chimneys to components used in industry. Consumption of heat-resistant paints is increasing rapidly worldwide as years pass. Generally, heat-resistant paints are expected to withstand temperatures between 300-800°C and are recommended to be applied at a dry film thickness of 30-50µ. Thermal resistance is a property imparted to the paint by its binder or, in other words, its resin. When organic resins are exposed to high temperatures, their structure deteriorates. Due to the thermal stability of Si-O-Si bonds, silicone resins have much better heat resistance compared to other resin types and are used in the design of high heat-resistant paints. Silicone resins that impart thermal resistance properties to paints consist of siloxane (Si-O) cage structures and silicate SiO2 or silsesquioxane (R*-SiO3/2) structures [1], Figure 1 shows the chemical structure of silicone resins. R groups are typically alkyl or aryl (methyl, phenyl) structures. Silicone resins are resistant to heat and radiation. They are transparent in the UV and visible regions. When silicone resins are formulated with appropriate pigments and fillers, they provide high thermal performance. [caption id="attachment_139262" align="aligncenter"] Figure 1. Chemical Structure of Silicone Resins [2].[/caption]Fillers are solid materials of micron size created by grinding natural minerals or precipitating inorganic substances. Fillers are the most commonly used input to reduce paint cost and improve its physical properties. They play a major role in determining the mechanical properties of the paint film. Some of the pigments and fillers used in heat-resistant paints and silicone coatings include rutile titanium dioxide, oxide pigments, spinel pigments, aluminium pigments, mica, talc, barite and mica-like iron oxide. The fillers selected for this study are specified in the table below. In this study, the effect of different filler ratios on adhesion and thermal resistance properties in heat-resistant paint formulation at constant PVC (Pigment Volume Concentration: the ratio of pigment volume to total non-volatile matter in the paint) was investigated. Six sigma methodology was utilized during the experimental design. A 2k full factorial experimental design was used. Two different variables were selected, film thickness and filler types. Two different levels were specified in the film thickness variable, 100µ and 200µ. Three different levels were specified in the filler types variable, barite, talc and mica. The ratios calculated for three different levels are specified in Table 2. Eight different paint formulas were prepared according to filler ratios (the PVC value of the paints is 25.7%). A total of 16 different studies were conducted. The grind fineness of the paints was observed as 10-15µ. The prepared paints were applied to DKP steel panels at wet film thicknesses of 100µ and 200µ. The paints applied to the panels were cured at 200°C for 30 minutes and then held at 600°C for 2 hours. Finally, tests were completed by performing a cross-cut adhesion test check on the paints demonstrating thermal resistance. Adhesion weaknesses were observed after the thermal resistance test in all studies with 200µ paint applied. The cross-cut test results of the studies with 100µ paint applied are shown in Figure 2. The adhesion performance of Standard Series 1 study resulted in GT0 according to ISO-2409 (ASTM 3359) standard, which is the best result where no film peeling occurs. In conclusion, the formulation of our heat-resistant paint with a PVC value of 25.7% in which the ratios of barite, mica and talc are equal was found to be successful. The Densurf products we would recommend for heat-resistant paint systems are listed in Table 3. Footnote: When working on heat-resistant paint, environmental conditions (temperature, humidity, etc.) should be kept constant. After the test time is completed in the ash furnace, the plates should not be removed immediately; the temperature should be allowed to drop below 200°C without disturbing the ash furnace. The cross-cut test should be applied after the plates have cooled to room temperature.

References

[1]. https://www.yukakimya.com/uploads/docs/boya-egitimi-2021-recineler.pdf [2]. https://en.wikipedia.org/wiki/Silicone_resin#/media/File:Silicone_resin.svg [3]. https://mvascientificconsultants.com/sem-analysis-testing-services-lab/talc-particle-electron-microscope-image [4]. Densification of Concrete using Barite as Fine Aggregate and its Effect on Concrete Mechanical and Radiation Shielding Properties/ Ahmad, Izaz/ Shahzada, / Ahmad, Muhammad Imran/ Khan, Fayaz/ Badrashi, Yasir/ Khan, Sajjad/ Muhammad, Noor/ Jan, Habib/2019/11/21/ Figure.2 [5]. Effect of E-Glass Fibers and Phlogopite Mica on the Mechanical Properties and Dimensional Stability of Rigid PVC Foams/ Jamel, Murtatha/ Khoshnoud, Parisa/ Gunashekar, Subhashini/ Abu-Zahra, Nidal/2015/06/15/Figure 1. Elif Şentürk Densurf Application Specialist Denge Kimya Hakan Göktürk Densurf Sales Engineer Denge Kimya