Abstract
The process of modifying aqueous powder suspension materials (APS) based on solid epoxy film-forming agents with highly dispersed powders of magnesium oxide was studied: production by ChemPur (n-MgO – primary size of particles is 36 nm), and magnesium oxide synthesized by a template method from the concentrated bischofite solution (MgOlab – primary size of particles is 102.8 nm). It was shown that presence of active functional surface OHgroups in both samples of magnesium oxide leads to the formation of secondary structures: aggregates and agglomerates. The nature of the influence of the size of aggregates of MgO particles and the conditions of dispersion on the properties of protective coatings is established. The nature of the influence of particle size and dispersion conditions on the properties of protective coatings is established. Optimal properties of coatings based on APS, sedimentation and aggregative stability of suspensions are implemented only under the condition of effective mechanical dispersion in a bead mill, when the most intensive destruction of large aggregates of n-MgO up to 50–60 nm occurs. The distribution of nanoparticle agglomerates in APS at the micro level (700–800 nm) using the MgO-lab does not lead to a significant change in the properties of APS and coatings based on them.It is shown that the introduction of n-MgO into APS allows reduces the curing temperature of the coatings from 110 to 90–100 °С. It is caused by the increase in the density of cross-linking of the spatial structure of polymer. The strength of modified coatings upon impact and tension increases by 2 times in comparison with the base composition, which does not contain nanomodifier, during curing of coatings at100 °C. In comparison with the known water-borne epoxy paints and varnishes, APS compositions are one-pack, they are more technological in use, have a long lifetime (up to 12 months in comparison with the viability of known two-pack epoxies, 1-8 hours). Materials can be used in industry for the protection of metal products, both as primers and as independent coatings.
Highlights
The process of modifying aqueous powder suspension materials (APS) based on solid epoxy film-forming agents with highly dispersed powders of magnesium oxide was studied: production by ChemPur (n-MgO – primary size of particles is 36 nm), and magnesium oxide synthesized by a template method from the concentrated bischofite solution (MgO- lab – primary size of particles is 102.8 nm)
It is shown that the introduction of n-MgO into APS allows reduces the curing temperature of the coatings from 110 to 90–100 °С
In comparison with the known water-borne epoxy paints and varnishes, APS compositions are one-pack, they are more technological in use, have a long lifetime
Summary
Институт общей и неорганической химии Национальной академии наук Беларуси, Минск, Беларусь. Изучен процесс модификации водно-суспензионных лакокрасочных материалов (ВСП) на основе твердых эпоксидных пленкообразователей высокодисперсными порошками оксида магния производства компании ChemPur (н-MgO – первичный размер частиц 36 нм) и оксида магния, синтезированного темплатным методом из концентрированного раствора бишофита (MgO-лаб – первичный размер частиц 102,8 нм). Установлен характер влияния размера агрегатов частиц MgO и условий диспергирования на свойства защитных покрытий. Оптимальные свойства покрытий на основе ВСП, седиментационная и агрегативная стабильность суспензий реализуются только при условии эффективного механического диспергирования на бисерной мельнице, когда происходит наиболее интенсивное разрушение крупных агрегатов н-MgO до 50–60 нм. Распределение агломератов наночастиц в ВСП на микроуровне (700–800 нм) при использовании MgO-лаб не приводит к существенному изменению свойств ВСП и покрытий на их основе. Что введение н-MgO в состав ВСП позволяет снизить температуру отверждения покрытий от 110 до 90–100 °С, что обусловлено увеличением плотности сшивки сетчатой структуры полимера. Ключевые слова: водно-суспензионные эпоксидные лакокрасочные материалы, наночастицы, оксид магния, структура, свойства.
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