• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.916-921
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• 2012

Sealant paste with silica immersed in cross-linked epoxy-acrylate polymer resin was prepared by thermal and UV curing process. The curing mechanism of polymer resin resulted from 2 functional groups of epoxy and acrylic structure. The properties of microstructure, thermal conductivity and mechanical strength were investigated for its various applications. The adhesion strength is increased by increasing the thermal curing time until 15 minutes, and curing efficiency is saturated over 20 minutes. The increase rate per day of pot life and viscosity is 4.8%, indicating it has excellent storage stability. It is found that the formulation of silica pastes can be applied to heavy industries, building materials, display and various industries.

• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.121-129
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• 2008

Environmental friendly UV-curable coatings, having excellent hardness, gloss, mar and chemical resistance, are commonly used for the wooden flooring coatings. Especially epoxy acrylate oligomers are chosen for the wooden flooring coatings, due to their thermal stability and fast curing. In this study, we investigated the effect of the acrylate functionality on the thermal stability and surface hardness. The thermal degradations of monomers, oligomer, photoinitiator and formulated coatings with different acrylate functionality were measured using a thermogravimetric analysis (TGA). And the surface hardness was also measured with a pendulum hardness tester to compare relationship between the thermal stability and the physical property. The cured coatings became thermally stable by crosslinking during UV-curing. Both the thermal stability and surface hardness of cured coatings were improved with increasing acrylate functionality.

• Textile Coloration and Finishing
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• v.29 no.1
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• pp.37-44
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• 2017

An issue of major concern in the utilization of laminated composites based epoxy resin is associated with the occurrence of delaminations or interlaminar cracks, which may be related to manufacturing defects or are induced in service by low-velocity impacts. A strong interfacial filament/brittle epoxy resin bonding can, however, be combined with the high fracture toughness of weak interfacial bonding, when the filaments are arranged to have alternate sections of shear stress. To improve this drawback of the epoxy resin, UV-thermal dual curable resin were developed. This paper presents UV-thermal dual curable resin which were prepared using epoxy acrylate oligomer, photoinitiators, a thermal-curing agent and thermoset epoxy resin. The UV curing behaviors and characteristics of UV-thermal dual curable epoxy resin were investigated using Photo-DSC, DMA and FTIR-ATR spectroscopy. The mechanical properties of UV-thermal dual curable epoxy resin impregnated CF prepreg by UV curable resin content were measured with Tensile, Flextural, ILSS and Sharpy impact test. The obtained results showed that UV curable resin content improves the epoxy toughness.

• Journal of the Korean Wood Science and Technology
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• v.27 no.3
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• pp.31-38
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• 1999

This paper deals with a coating technique of hardening surface layer of softwood{Larix leptolepis) flooring board to improve its surface properties such as hardness and abrasion resisitance without spoiling its exellent qualities such as beautiful color tones and great strength. For surface hardening of the wood, polyurethane wood sealer was used as under coat, polyurethane sanding sealer as intermediate coat, and UV-curing epoxy acrylate and urethane acrylate varnishes as top coat. The hardness of the wood was improved by the coating treatment and it was similar to that of high density hardwood such as oak, keruing. The abrasion resistance of the coated wood was greatly improved by UV curing epoxy acrylate or urethane acrylate varnishes. Adhesion properties and impact resisitance of the coated wood surface were also good. It was suggested that the well-coated larch wood could be used as interior flooring board as substitute for hardwood such as keruing.

• Journal of Adhesion and Interface
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• v.10 no.4
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• pp.191-198
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• 2009

UV-curable aliphatic epoxy acrylates were prepared by the reaction of glycerol diglycidyl ether (GDE) with 2-carboxyethyl acrylate (2-CEA) or 2-hydroxyethyl acrylate (2-HEA). The structures of the epoxy acrylates were characterized by FT-IR, $^1H$-NMR, and $^{13}C$-NMR and the yield was obtained by prep-LC. The UV- and the thermal-curing behaviors of the product were investigated using photo-DSC and DSC, respectively. The reactivity of 2-CEA was higher than 2-HEA and the yield of the product (GEA-C) which was prepared using 2-CEA was about 83%. The maximum UV-curing time ($T_{max}$) of the GEA-C contained non-reactive components and by-product was about 10 seconds. The GEA-C showed low color difference (${\Delta}E^*$), low viscosity, and good thermal stability - its value was 2.51, 192 cps, and $299^{\circ}C$ (at 5% weight loss), respectively. The activation energies ($E_a$) of thermal-curing reaction calculated from Kissinger and Ozawa-Flynn-Wall method were 91~92 kJ/mol.

• Polymer(Korea)
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• v.37 no.1
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• pp.121-126
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• 2013

UV-curable high refractive index di-functional epoxy acrylate, 4,4'-thiodibenzenethiol diglycidyl ether diacrylate, was synthesized from acrylic acid and 4,4'-thiodibenzenethiol diglycidyl ether that was obtained by reacting 4,4'-thiodibenzenethiol and epichlorohydrin using a direct method (Taffy process). Its chemical structure was identified by $^1H$ NMR and FTIR. After its dilution with a reactive diluent, 2-phenoxythiol ethyl acrylate as 5, 10, 15, 20, and 30 wt% content, the relationship between their viscosity and refractive index was investigated. Their degree of cure decreased with increasing the amount of reactive diluent, and the refractive index of UV-cured film increased with increasing the degree of cure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.421-421
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• 2008

Generally, the polymer thick-film resistors for embedded organic or hybrid substrate are patterned by screen printing so that the accuracy of resistor pattern is not good and the tolerance of resistance is too high(${\pm}$20~30%). To reform these demerits, a method using Fodel$^{(R)}$ technology, which is the patterning method using a photosensitive resin to be developable by aqueous alkali-solution as a base polymer for thick-film pastes, was recently incorporated for the patterning of thermosetting thick-film resistor paste. Alkali-solution developable photosensitive resin system has a merit that the precise patterns can be obtained by UV exposure and aqueous development, so the essential point is to get the composition similar to PSR(photo solder resist) used for PCB process. In present research, we made the photopatternable resistor pastes using 8 kinds of epoxy acrylates and a conductive carbonblack (CDX-7055 Ultra), evaluated their developing performance, and then measured the resistance after final curing. To become developable by alkali-solution, epoxy acrylate oligomers with carboxyl group were prepared. Test coupons were fabricated by patterning copper foil on FR-4 CCL board, plating Ni/Au on the patterned copper electrode, applying the resistor paste on the board, exposing the applied paste to UV through Cr mask with resistor patterns, developing the exposed paste with aqueous alkali-solution (1wt% $Na_2CO_3$), drying the patterned paste at $80^{\circ}C$ oven, and then curing it at $200^{\circ}C$ during 1 hour. As a result, some test compositions couldn't be developed according to the kind of oligomer and, in the developed compositions, the measured resistance showed different results depending on the paste compositions though they had the same amount of carbonblack.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.157-163
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• 2012

Using six kinds of epoxy acrylates and a conductive carbon black, photosensitive resistor pastes were fabricated and then their developability in alkaline aqueous solution and the resistance values after thermal curing were evaluated. In order to impart the photocurability by UV exposure and the developability on alkaline solution, epoxy acrylate oligomers with carboxyl group, acrylate monomers, a photoinitiator and so forth were used. In addition, an organic peroxide was added into the paste to get a thermally curable composition. As a result, some of the pastes were not developed depending on the kinds of oligomers and, in the developed pastes, the measured resistance showed the different values depending on their compositions, even though they contain the same amount of carbon black. Finally, the optimum oligomer was selected and then, by adjusting the amount of carbon black, the kind of monomer and the curing temperature, the photosensitive resistor paste composition which showed the sheet resistance of about 0.5 $k{\Omega}/sq.$ could be obtained.

• Journal of the Korean Wood Science and Technology
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• v.28 no.1
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• pp.28-35
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• 2000

This paper deals with a coating technique for hardening surface layer of softwood(Larix leptolepis) flooring board to improve its surface properties such as hardness and abrasion resistance, Two coating methods were applied for surface hardening of the wood in this study. First, several functional monomers were added in UV-curing epoxy acrylate varnish. Secondly, unsaturated polyester varnish was used as under coat and acryl varnish including anti-abrasive agent was used as top coat. The hardness of the treated wood was similar to that of high density hardwood such as keruing by the first coating method. The abrasion resistance of the coated wood was greatly improved by the second method. Adhesion properties and impact resistance of the coated wood surface were also good. It was suggested that the well-coated softwood could be used as interior flooring board for heavy walking as substitute for hardwood.

• Journal of Adhesion and Interface
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• v.11 no.2
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• pp.41-49
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• 2010

Furan-containing epoxide monomers (8, 9) were designed and synthesized as carbon-neutral, environment-friendly adhesion material. Bicyclic skeleton were constructed using the Diels-Alder reaction of furan and methyl acrylate, both readily accessible starting material from a biomass via bio-refinery process. After reduction of ester functionality, resulting hydroxyl moieties were coupled to epichlorohydrin to provide the epoxy-functionalized furanic monomers (8, 9). The structure of new furanic monomers was confirmed by $^1H$ and $^{13}C$ NMR spectroscopy. As UV-curable monomers, basic properties such as UV curing time and the extent of UV curing were evaluated by photo DSC. Photo-curing shrinkages were measured by linear variable differential transformer transducer (LVDT) and the effect of molecular structure on shrinkage was considered. In addition, new synthetic compounds showed the shear strength over 3 MPa when they were photo-cured between polycarbonate plates, which indicates these compounds are feasible to use as photo-curable adhesive materials.