• Journal of the Korean Applied Science and Technology
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• v.38 no.2
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• pp.476-487
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• 2021

To prepare acrylic resin coatings containing 70% of solids, we used n-butyl methacrylate(BMA), methyl methacrylate(MMA), 2-hydroxyethyl methacrylate(2-HEMA), and acetoacetoxyethyl acrylate(AAEA), caprolactone acrylate(CLA) as raw materials, the glass transition temperature(T_g) of acrylic copolymer was adjusted around 50 ℃. The viscosity and molecular weight of the acrylic resins was increased with increasing OH values. Di-tert-amyl peroxide was found to be the suitable initiator to get high-solids acrylic resins. The optimum reaction conditions found in the study are 5 wt% of initiator, 4 wt% of chain transfer agent, 4 hrs of dropping time, and 140 ℃ of reaction temperature. The structure of the synthesized resins were characterized by FT-IR and ¹H-NMR spectroscopy. Number average molecular weight of 1900~2600 and molecular wight distribution of 1.4~2.1 were obtained. Crosslinked acrylic urethane clear coatings were obtained by curing reaction between the synthesized acrylic resins and hexamethylene diisocyanate trimer(Desmodur N-3300), the equivalent ratio of NCO/OH was 1.2/1.0. The physical properties from the following studies were carried out: viscosity(Zahn cup #2), adhesion, drying time, pot-life, pensil hardness, and 60° specular gloss. Various properties of the acrylic urethane clear coatings were also evaluated on the coating specimens. Adhesion property to a substrate, drying time, pot-life, pencil hardness, and 60° specular gloss of prepared paint showed quite good properties. Futhermore, prepared paint containing 10% of CLA showed quite good properties for adhesion, low viscosity and high hardness.

• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.557-566
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• 1988

The causes of failure in the deketalization of rigid ${\beta}$-aminoketals were separately investigated by examining the deketalization of 3 ketals, 2-ethylenedioxy-l-acenaphthenylamine (2), N-(2-ethylenedioxy-l-acenaphthenyl)acetamide(13) and trimethyl-2-ethylenedioxy-1-acenaphthenylammonium iodide(14), and by examining the deketalization of non-rigid ${\beta}$-aminoketal, 2-amino-l-ethylenedioxyacetophenone(19) and non-rigid aliphatic acetals, dimethylaminoformaldehyde dimethylacetal (20) and 2-aminoactaldehyde dimethyl acetal(21). While compounds 2 and 14 were not able to be hydrolyzed in the various acidic conditions 13 was easily deketalized. The result indicated the importance of electrostatic repulsion in the possible dicationic intermediates as a factor of failure in the deketalization. The observations of easy deketalization of compounds 19, 20 and 21 indicated that the structural characters of rigid $\beta-aminoketals$ are also important factors in the hydrolysis of ${\beta}$-aminoketals.