• Journal of Adhesion and Interface
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• v.18 no.3
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• pp.134-140
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• 2017

In this study, we made UV cured acrylic pressure sensitive adhesive containing silicone-urethane-acrylate (SUA) oligomer for a coating on protective film and investigated the effect of SUA oligomer content and UV-dose on adhesion properties. The results illustrated that peel strength decreases with increasing oligomer content and UV-dose, while holding power increases. The gel fractions sharply increased after UV irradiation and then remain constant with prolonged UV exposure. From peel-off test, sample S70 (70% oligomer content) shows the best peelability and removability without remaining any mark or adhesive material on the test substrate than S50 (50% oligomer content) and S60 (60% oligomer content). Sample S70 also showed a surface energy lower than $26mJ/m^2$ and a transmittance higher than 95% at UV-dose 1857 and $2270mJ/cm^2$ which met the required properties for protective film application.

• Journal of Convergence for Information Technology
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• v.7 no.4
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• pp.75-81
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• 2017

The design trend of information technology is quickly changed with the times. The design trend of information display is a bezel-less display, recently. The bezel-less display or edge-less display is a new trend of mobile phone display. In this study, the shading tape was manufactured for assembling process of touch panel display with the high screen-to-body ratio so-called bezel-less display. The shading tape was fabricated on PET film with the UV curable acrylic pressure sensitive adhesive(PSA) by roll-to-roll process. The UV curable PSA was synthesized with the eco-friendly toluene-less manufacturing method. The adhesive power of manufactured shading tape was investigated by motorized tensile testing machine. The thixotropic, maintaining property of cutting shape, was characterized by field emission scanning electron microscope. As results, the shading tape exhibits high adhesive power and good thixotropic performance suitable for assembly process of touch panel display. The functional shading tape will be expected to improve productivity of assembly process of touch panel display.

• Journal of Adhesion and Interface
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• v.12 no.2
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• pp.47-55
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• 2011

UV-curable coatings have been used in various industries due to their advantages such as high mechanical property, good solvent resistance, fast curing process and low volatile organic compounds. However, a lack of flexibility of UV-cured films is a weak point for the pre-coated system of roll-to-roll process. In this study, UV-curable polycarbonate-based methacrylates were synthesized with polycarbonate diol, isophorone diisocyanate and 2-hydroxyethylmethacrylate to improve flexibility of the UC-cured films. The effects of polyol molecular weight, content of photoinitiator and monomers on the UV-curing behavior, flexibility and properties were investigated. The UV-curing behavior was measured by a photo-DSC, the pendulum hardness, tensile strength, viscoelastic properties were also evaluated.

• Elastomers and Composites
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• v.45 no.3
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• pp.217-222
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• 2010

Paved roads are suffered from the permanent plastic deformation in hot summer and cracks in cold winter, which are detrimental to safe driving. This leads to necessity of modification of asphalt to resist those deformation. In this study, two kinds of modifiers were examined; organic polymers and a photoinitiator which is activated by ultraviolet lay. The mechanical and rheololgical properties of modified asphalts were examined using UTM and rheometer. Results showed that the properties were varied depending on the types of polymer and irradiation time. UV irradiation increased the tensile strength and storage modulus of thermoplastic polymer-modified asphalt, however UV was not effective on thermoset polymer. According to long term ultraviolet curing test, properties of the polymer/photoinitiator-modified asphalt did not decrease, but rather increase for 20 years. This indicates that the useful life of the asphalt could be extended by addition of photoinitiator.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.5
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• pp.411-419
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• 2000

In this paper we have investigated the surface degradation by ultraviolet-irradiation in high-temperature vulcanized silicone rubber. Through the measurement of surface potential decay by corona-charging and of contact angle it is found that the change of surface electrostatic properties and the decrease of contact angle under UV-radiation. For the changes in micro-morphological and chemical structure of the UV-treated silicone rubber we utilized several analytical techniques such as SEM, ATR-FTIR,XPS. From this study it is shown that the chemical reactions(scissoring of side chain(S-$CH_3$) cross-linking and branching) occur on the surface of silicone rubber during the UV-irradiation. Also we obtained the results of the loss of low molecular weight chain by cross-linking and oxidation reaction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.339-345
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• 2018

We investigated the curing properties of cured coatings for a multi-focal UV-LED. The coatings are for LEDs that operate at multiple UV wavelengths, unlike conventional single-wavelength UV-LEDs. Using UV-LED light sources with wavelengths of 365, 395, 420, and 450 nm, we analyzed the optical characteristics such as the direction of light flux and light source. We also analyzed the curing characteristics at each UV-LED wavelength to optimize the LED for composite wavelengths. The curing performance state was predicted through computer simulation for when the multiple wavelengths of UV light sources are superimposed, and then actual LEDs were designed and fabricated. To improve the internal high-speed curing, a multi-spot module was fabricated, in which each LED is condensed, and multiple wavelengths are synthesized and condensed at the same position. The adhesive strength, surface hardness, and internal hardness of the curing agent were tested by varying the wavelength combination conditions. The surface hardening and internal hardening were compared and analyzed using a hardness tester and FT-IR analyzer. As a result, the characteristics of the surface and internal hardness were improved by a multi-spot method in which four wavelengths were overlapped in a UV-LED rather than a single wavelength.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.127-128
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• 2005

UV-curable pressure sensitive adhesives were prepared by blending acrylic copolymer, copolymerized with butyl acrylate (BA), acrylic acid (AA) and vinyl acetate (VAc) by solution polymerization, triethyl amine (TEA) and trimethylolpropane triacrylate (TMPTA). The PSAs were evaluated by peel strength with varying contents of TMPTA and UV dose, and also glass transition temperature($T_g$) of PSAs were measured. When exposed on UV irradiation, the PSAs showed the decreased peel strength and increased $T_g$. And following UV irradiation, the PSAs did not leave any residue on wafer after peel off PSA.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4388-4397
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• 2015

The purpose of this study was to research the property change of acrylic resins depending on the induced-beam change and research the improved physical property of dry-heat and microwave-cured dental place acrylic resin in order to develop the acrylic resins with the optimum characteristic. As a result of observing flexural rigidity, hardness and color difference, the dry-heat-cured specimens of Vertex RS and Paladent 20 showed ideal property at 5, 15, and 25 kGy irradiation. The microwave-cured specimens of Vertex RS and Paladent 20 showed ideal property at 5 kGy irradiation. The correlation analysis showed a positive correlation among ARD, flexural rigidity (0 418), E coefficient (0.675) and Barcol hardness (0 588). The radiation cure technology is helpful for relieving the contamination caused by the manufacture of polymer composite. It can significantly contribute to the fusion of ultra violet cure technology and nano technology and the improvement of mechanical property without giving effect to the workability of polymer.

• Journal of Adhesion and Interface
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• v.4 no.1
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• pp.9-17
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• 2003

The UV hard coating materials are attracting more and more attention to modern industry, in terms of the development of low or non solvent coating materials which will contribute to economizing both materials and energy and to reducing pollution. This study was performed in order to invent UV curable coating materials containing colloidal silica which have actual industrial applications. As results of experiments, the oligomers type and the concentration of colloidal silica acrylate oligomer (SAOC) have an influence on various especially, The properties of UV hardening cooling, such as chemical, abrasion resistance and weatherability, were greatly enhanced, the impact properties of coated polycarbonate substrate were improved compared with the noncoated that. The UV cured films containing 30 wt% SAOC obtained showed the best properties.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.596-602
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• 2018

Nanoimprint lithography (NIL) is an emerging technology that enables cost-effective and high-throughput nanofabrication. In ultraviolet (UV) NIL, low-cost and high-speed production can be achieved using a non-vacuum environment at room temperature and low pressure. However, there are problems with the formation of bubble defects in such an environment. This paper investigates the shape of the mold cavity and the bubble defect formation in UV NIL in a non-vacuum environment. The bubble defect formation was simulated using two-dimensional flow analysis and the VOF method for commonly used cavity mold shapes (rectangular, elliptical, and triangular). The characteristics of the resist flow front and various contact angles were also analyzed. The shape of the mold cavity had a very significant effect on the bubble defect formation. For all cavity shapes, a smaller contact angle with the mold and larger contact angle with the substrate decreased the possibility of bubble defect formation. The elliptical shape was the most effective for preventing bubble defect formation.