• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.160-161
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• 2021

To prepare polyurethane coatings for top coatings of automobiles, acrylic resins containing 75% of solids were synthesized by a radical polymerization. The viscosity of the acrylic resins was increased with increasing OH values. Crosslinked acrylic-urethane clear coatings were obtained by curing reaction between the synthesized acrylic resins and hexamethylene diisocyanate(HDI) trimer(Desmodur N-3600). The physical properties from the following studies were carried out : viscosity(Zahn cup #2), adhesion, pensil hardness, and 60° specular gloss. Various properties of the acrylic-urethane clear coatings as top coatings of mobile coat were evaluated on the coating specimens. Adhesion property to a substrate, 60° specular gloss, and pencil hardness of prepared paint showed quite good properties.

• Economic and Environmental Geology
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• v.53 no.3
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• pp.287-296
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• 2020

Mine Reclamation Project is being carried out with the aim of ensuring a sustainable green living and helping to develop eco-friendly mines by analyzing, removing and preventing the harmful factors. Mines developed during the japanese colonial period and mining boom period are still not repaired throughout the country, and from these scattered risks, public safety is worth pursuing as a top priority. The project that is close to public safety in the mine recalmation project is an emergency treatment, and the most widely used method is a filling method similar to the ground subsidence prevention. If dangerous mine cavity or tunnels are located in the mountains, charging with existing materials may not be possible, or unreasonable cases may occur, and new methods of technological development are required. Emergency actions should be carried out safely and efficiently to prevent the loss of precious people's lives on the hiking paths adjacent to dangerous mining sites. In these field conditions, urethane foam materials may be an alternative. In this study, the applicability of urethane foam materials in mining was reviewed through overseas cases. It was also tested on the appropriate depth of top soil for the protection of urethane foam materials through forest fire simulation test. The test result show that approximately 15cm of soil covering (recommended 20cm over) was suitable for maintaining the function of foam materials from forest fires.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.229-232
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• 2006

Two novel synthetic route proposed for Hydro-Terminated Poly(EO-ran-THF) and tri-block(PEC-PTHF-PEG) copolymer by cationic ring-opening polymerization of tetrahydrofuran(THF) and ethylene oxide(EO) and just by polymerization of EO on poly-THF, respectively. Polyurethane was synthesized from random and tri-block HTPE using N-100/IPDI mixture as curing agent, and TPB(Triphenylbismuth) as catalyst. The mechanical properties of resultant polyurethane after mixing with various ratio of isocyanate was also investigated. Finally, the post treatment process of HTPE based on amount of catalyst used in the synthesis was studied, to evaluate the optimum curing condition for the polyurethane propellant binder.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.04a
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• pp.176-179
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• 1999

• Journal of the Korean Applied Science and Technology
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• v.32 no.3
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• pp.528-535
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• 2015

Humanity has tended pursuing beauty. Pearls has been loved by many people for thousands of years as a symbol of wealth and status. Today, Artificial pearl were made using organic pigment due to bright colors and easy coating process. But the new coating technique is required due to low durability, weather resistance and difficulty of luxurious luster expression. This study, nitrocellulose and urethane were used as binder and inorganic pigment were used to expression of colors. Experimental variable of artificial pearl with nitrocellulose and solvent ratio, urethane and curing agent ratio, the amount of pearl number of coating, drying temperature and time, and coating technology was developed. The coated artificial pearl was evaluated with color-difference meter, ultraviolet ray resistance, promotion weathering. Urethane was better than nitrocellulose when compared with weather resistance, acid-alkalinity resistance.

• Journal of the Korean Chemical Society
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• v.27 no.1
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• pp.58-65
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• 1983

The mechanical properties (tensile strength, 100% modulus and hardness) of the urethane elastomers prepared from hydroxyl terminated polybutadiene (HTPB), several low molecular weight diols (ethylene glycol, 1, 3-propane diol, 1,4-butane diol, 1,5-pentane diol and 1,6-hexane diol) and two kinds of diisocyanates(TDI: toluene diisocyanate, IPDI: isophorone diisomechanical properties were enhanced for the increases of the concentrations of the urethane group, as predicted. In case of TDI, when the mechanical properties of the elastomers were plotted patterns were observed, which can be explained by hydrogen bondings depending on the number of the methylene carbons. But the mechanical properties of the elastomers derived from IPDI had decreasing curves against the number of methylene carbons in low molecular weight diols, without the characteristic zigzag patterns.

• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.52-61
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• 2009

In this study, TAPEH (t-amyl peroxy 2-ethyl hexanoate) was selected for the reaction initiator which is a core factor for developing acrylic polyol binder. Tone M100 (caprolactone acrylate), 4HBA (4-hydroxy butyl acrylate), and 2HEMA (2-hydroxy ethyl methacrylate) were used for hydroxy-monomers. To check the applicability of raw materials mentioned above into the binders of 2 components acrylic polyurethane paint and reduce the VOC, the reactivity and film performance by different kinds of aliphatic polyisocyanate hardeners which are already generalized were reviewed. As the Tin-based catalyst has been regulated, the comparison test of reactivity and performance between the conventional catalyst and non-toxic metal catalyst recommended as the alternative was conducted as well. As a result, we were able to obtain the basic data which are necessary for applying 2 components high solid polyurethane paint and also reached a conclusion that it can be applied for developing new paints in terms of high performance, workability and environmental care.

• Elastomers and Composites
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• v.33 no.5
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• pp.324-334
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• 1998

SBR, polyurethane, acryl and epoxy latex were seperately mixed with ethylene-vinylacetate emulsion(EVA) in the range of $0{\sim}50%$ (wt.% ). For the mixtures, the various physical properties were examined. The viscosity of mixtures was mainly influenced by compatability with EVA emulsion, was decreased within 20% (wt.% ) of latex content, and showed the similar values over 20% (wt.% ) of latex content. The workable time of cement mixtures was mainly depended on the reactivity with cement. The formation of film could be only within $30{\sim}40$ minutes from mixing cement. The tack-free time of mixtures was influenced by the sorts of resin and the quantity of cement. The slow order of tack-free time was epoxy mixtures>SBR mixtures>urethane mixtures>acryl mixtures. The pencil hardness of mixtures was $4B{\sim}2H$, represented higher value in cement mixtures than in emulsion state.

• Polymer(Korea)
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• v.38 no.1
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• pp.1-8
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• 2014

The effects of surface color and morphology on the mar behaviors of urethane-acrylate coated surfaces were examined. The superiority of mar resistance was observed in the order of white, red and black-colored samples. This can be explained by a contrast effect. In other words, in case of black colored sample, it takes place the defuse reflection of the incident light on the damaged region where mar damage exerts, leading to whitening phenomenon. Therefore, the damaged region is easily recognized by contrasting the black background. On the other hand, it is difficult for the white-colored sample to perceive the mar-damaged area by the white background acting as protecting coloration. As the gloss of urethane-acrylate coated surface increases, it is observed that there is an increase in the number of carbonyl (-C=O) function group, amount of ethylene and silica. The enhancements of surface rigidity by adding the silica particles and formation of carbonyl function groups by the surface oxidation lead to the increase in mar resistance, while the increase of polyethylene wax is responsible for the improved gloss and smooth-faced surface. Based on the above findings, technical approaches leading the improvement of mar resistance of the urethane-acrylate coated surface are discussed.

• The Journal of Engineering Geology
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• v.31 no.1
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• pp.83-101
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• 2021

The high-density polyurethane method uses the instantaneous expansion pressure of injected material to stabilize soft ground, allowing reinforcement, restoration, and construction to be carried out in suboptimal ground conditions. Under normal and, even poor conditions, the method is easily applied because the working time is very short. The method is environmentally friendly and results have excellent durability. The purpose of this study was to verify the physical and mechanical properties of high-density polyurethane in the ground. Initial testing of strength, direct shear, and soil environment stability was followed by testing for permeability in order to address environmental concerns. The results of the experiments showed that the internal friction angle was about twice as high and the adhesion was about 2.5 to 3.5 times higher than for dense and hard clay, and that the permeability factor was significantly lower compared with the existing grouting method, within the range of 1.0 × 10-5.