![]() No pigments or fillers were added to the formulation so as to eliminate, as much as possible, side effects on the coating’s properties and the changes caused by the modification. The coatings obtained were crosslinked stoichiometrically with a modified polyamide curing agent. The viscosity of the formulation increased significantly only above an ALBIDUR concentration of approximately 15% w/w (Figure 6). Because no further solvent was added, the additional silicone elastomer particles in the formulation led to an increase in the solids content. The ratio between the two epoxy resins and the solvents was thus held constant over the whole test series. The amount of epoxy resin 2 in the original formulation was reduced by the amount of epoxy resin 2 introduced by the ALBIDUR in the formulation. To this was added an ALBIDUR product consisting of silicone elastomer particles (40%) and the Bisphenol A epoxy resin 2 (60%) used in the test formulation. Further solvent was added to reduce the viscosity as well as a wetting additive to improve substrate wetting. Test FormulationsĪ simple epoxy resin formulation consisting of two epoxy resins based on Bisphenol A were used as a base (Table 1). The pencil and Erichsen pencil hardness were also determined along with the sliding resistance of the coating surfaces. The specimens were also subjected to further tests such as the Constant Climate Condensation Water Test (DIN EN ISO 6270) and Salt Spray Test (DIN EN ISO 9227 NSS). Multi Impact Stone Chip Test (DIN EN ISO 20567-1). The following application-related tests from the industrial paint sector were used to evaluate the influence of silicone elastomer particles on the impact strength:įalling Weight Impact Test (DIN EN ISO 6272-1) The products are solvent-free and can be stored for 12 months at room temperature. The particle sizes and the differing refractive indices of the silicone elastomers and the surrounding resin matrix impart the white color of the silicone elastomer core-shell particle dispersion (Figure 5).īecause this is a patented platform technology, it is possible to upgrade various resin systems, such as polyols, acrylates or epoxies, to become ALBIDUR, based on the use of customized silicone elastomer formulations. The manufacturing process yields particle sizes between 0.1 and approximately 3 µm, with over 90% of the particles smaller than or equal to 0.3 µm in size (Figure 4). The external forces are largely absorbed during this process by the elastomer particles, like a shock absorber, and thus ward off fracturing in the coating. Due to the statistical distribution within the binder matrix, the elastomer particles ensure a uniform impact strength. This behavior is retained during curing so that a statistical distribution of all core-shell particles exists during both the uncured and fully cured stages (Figure 3). 4īecause of the choice of shell and the related stabilization, there is no tendency for settling or phase separation of the particles. The shell is adapted to the chosen binder matrix and, additionally, possesses suitable functional groups to link to the binder matrix of the coating (Figure 2). As a result, there is hardly any change in the glass transition temperature in the cured paint film. ![]() No covalent linkage exists between the core and the shell the shell is simply physically anchored to the core. The center is a silicone rubber core that promotes the tough, resilient characteristics, encased by a shell. 3 The special feature is the two-phase nature of the core-shell particle. This article describes the use of ALBIDUR ® core-shell silicone elastomer technology in a two-pack epoxy resin system and its influence on the mechanical properties of the coating generated.ĪLBIDUR technology involves the use of a patented process to permanently incorporate in-situ small silicone elastomer particles in a resin carrier (Figure 1). Using silicone core-shell rubber technology, it is possible to combine these originally contradictory properties. to generate tough, resilient but hard coatings. It is desirable to incorporate some ductile segments in the highly crosslinked, brittle matrix without impairing the network or mechanical properties, i.e. In this type of in-situ generation of particles, however, it is extremely difficult to control the particle size without fundamentally altering the properties of the polymer matrix. Combination with a second microphase, such as dispersed rubber or thermoplastics, can lead to significantly improved toughness. This weakens the network density of the system as well as the surface hardness and chemical resistance. Incorporating flexible constituents in a highly crosslinked binder matrix results in markedly improved impact strength but a lower degree of crosslinking.
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