Ultraviolet Coatings Research Articles

Effect of Melamine Formaldehyde Resin Encapsulated UV Acrylic Resin Primer Microcapsules on the Properties of UV Primer Coating.

Ultra-Violet (UV) coatings are widely adaptable of substrates and produce low emissions of volatile organic compounds. UV coatings can extend service life by adding self-healing microcapsules that restore integrity after sustaining damage. In this study, UV coating was used as a core material; microcapsules were produced and added to the UV coating to enhance its self-healing property, providing a good protection for both the UV coating and the substrate. UV primer microcapsules were prepared with UV primer as the core material and melamine formaldehyde resin as the wall material. The UV primer containing more than 98.0% solids content was mainly composed of epoxy acrylic resin, polyester acrylic resin, trihydroxy methacrylate, trimethyl methacrylate, and photo initiator. The preparation process of the UV primer microcapsules was optimized. Further, the UV coating was prepared with better UV primer microcapsules, and the effects of the UV primer microcapsules alongside the comprehensive properties of the coating were studied. The best preparation process for the UV primer microcapsules was as follows: the wall-core mass ratio was 1:0.50, Triton X-100 and Span-20 as emulsifiers with an HLB value of 10.04, the microcapsule reaction temperature was 70 °C, and the reaction time of the was 3.0 h. When the quantity of the UV primer microcapsules increased in the coating, color difference ΔE of the coating increased, gloss decreased, transmittance decreased, elongation at break increased and then decreased, roughness increased, and self-healing rate first increased and then decreased. When the addition of the UV primer microcapsules reached 2.0%, the color difference ΔE of the coating was 1.71, the gloss was 106.63 GU, the transmittance was 78.80%, the elongation at break was 3.62%, the roughness was 0.204 μm, and the self-healing rate was 28.56%, which were the best comprehensive properties of the UV primer. To improve the comprehensive properties of the UV coatings, the UV coatings were modified by a microcapsule technology, which gave the UV coatings a better self-healing property. The application range of microcapsules for the UV coatings was broadened. Based on the previous research of microcapsules in UV coatings, the results further refined the study of the effects of adding self-healing microcapsules to UV coatings using the UV coating itself as the core material.

Characteristics and environmental and health impacts of volatile organic compounds in furniture manufacturing with different coating types in the Pearl River Delta

Volatile organic compounds (VOCs) are essential pollutants affecting ambient air quality. In the Pearl River Delta of China, furniture manufacturing contributes significantly to VOCs emissions, mainly from coatings. Therefore, the source substitution of coatings is the most effective way to reduce VOCs emissions. In this study, eight typical furniture enterprises with five different coatings types (traditional solvent coatings (solvent and solvent ultraviolet (UV) coatings) and low VOCs content coatings (waterborne, waterborne UV, and powder coatings)) were selected for field monitoring to reveal differences in VOCs emission characteristics, environmental impacts and health risks between traditional solvent coatings and low-VOCs coatings. The results showed that solvent coating VOCs have the highest concentration (143.32 mg/m3) and are much higher than that of solvent UV coating (45.96 mg/m3) and other coatings (≤11.81 mg/m3). The highest proportion of VOCs of solvent (UV) coating is aromatic hydrocarbons (50.73% (44.05%)). While oxygenated VOCs rank first in low-VOCs coatings (47.81%–59.20%). Compared with other coatings, the solvent coating has the greatest contribution to the formation potential of ozone and secondary organic aerosols. Meanwhile, the solvent coating has the highest carcinogenic risk of ethylbenzene in the spraying workshop (8.53 × 10−6), and only solvent coating in the spraying workshop has the non-carcinogenic risk of xylene (1.07). Finally, through scenario analysis, the environmental benefits of low-VOCs coatings substituting solvent coating were quantified. The study will help accelerate the process of source substitution of coatings and promote cleaner production in the furniture industry.

High performance {Nb5TaX12}@PVP (X = Cl, Br) cluster-based nanocomposites coatings for solar glazing applications

ABSTRACT The development of highly ultraviolet (UV) and near-infrared (NIR) absorbent transparent coatings is an important enabling technology and area of research for environmental sustainability and energy conservation. Different amounts of K4[{Nb5TaXi 12}Xa 6] cluster compounds (X = Cl, Br) dispersed into polyvinylpyrrolidone matrices were prepared by a simple, nontoxic and low-cost wet chemical method. The resulting solutions were used to fabricate visibly transparent, highly UV and NIR absorbent coatings by drop casting. The properties of the solution and films were investigated by complementary techniques (optical absorption, electrospray ionization mass spectrometry and Raman spectroscopy). The UV and NIR absorption of such samples strongly depended on the concentration, dispersion and oxidation state of the [{Nb5TaXi 12}Xa 6] nanocluster-based units. By varying and controlling these parameters, a remarkable improvement of the figures of merit TL/TE and SNIR for solar-glazing applications was achieved compared to the previous results on nanocomposite coatings based on metal atom clusters.

Coating-derived VOCs Emission Characteristics and Environmental Impacts from the Furniture Industry in Guangdong Province

To determine the differences in emissions among different types of coatings, such as solvent-based, water-based, solvent-based ultra-violet(UV), water-based UV, and powder coatings, representative furniture manufacturing companies were selected for analysis. The emission concentrations and compositional characteristics of volatile organic compounds(VOCs) in different types of coatings were compared and studied. The ozone formation potential(OFP) and secondary organic aerosol formation potential(SOAFP) of the different types of coatings were also analyzed. Solvent-based coatings has higher TVOC concentrations, OFPs, and SOAFPs than water-based, solvent-based UV, water-based UV, and powder coatings. The concentrations and composition of VOCs emitted from the different types of coatings were also different. The main VOC groups of the solvent-based and solvent-based UV coatings were aromatic hydrocarbons and oxygenated volatile organic compounds(OVOCs). Specifically, the proportions of aromatic hydrocarbons are 41.91%-60.67% and 42.51%-43.00%, respectively, and the proportions of OVOCs were 24.75%-41.29% and 41.34%-43.21%, respectively. OVOCs accounted for the highest proportion of VOCs in the water-based, water-based UV, and powder coatings, at 54.02%-62.10%, 55.23%-64.81%, and 42.98%-46.45%, respectively. The major VOC compound of the solvent-based coatings was styrene(14.68%), and the main component of the water-based coatings was methylal(14.61%). The main species of VOCs from the solvent-based UV and water-based UV coatings were butyl acetate(15.36% and 20.56%, respectively). The most abundant species from the powder coatings was ethyl 3-ethoxy propionate(20.19%). Aromatic hydrocarbons were the most important contributor to the OFP of the solvent-based and solvent-based UV coatings, accounting for 79.84% and 80.32%, respectively. Aromatic hydrocarbons(51.48% and 36.71%) and OVOCs(42.30% and 41.03%) were the major contributors to the OFP of the water-based and water-based UV coatings, respectively. Aromatic hydrocarbons(43.46%), OVOCs(28.06%), and olefins(25.24%) were the main factors affecting the OFP of the powder coatings. Aromatic hydrocarbons dominate the SOAFP of solvent-based, water-based, solvent-based UV, water-based UV, and powder coatings, accounting for more than 99%.

Characteristics of Volatile Organic Compounds in Wood Coatings and Automotive Coatings in China

Presently, there are a few studies on the measurement of industrial organic solvents in China. To determine the content and species of volatile organic compounds (VOCs) in industrial organic solvents and to provide the emission factors of organic solvents, the Chinese wood and automotive coatings, which accounted for the largest proportion of production in the world, were investigated. Coating samples were obtained by sampling from companies and buying from markets, and were measured in accordance with the domestic standard testing methods for coatings. The content and composition spectrum of VOCs in the coatings were determined, and the ozone formation potential (OFP) was then calculated. The results showed that for wood coatings, the average content of the VOCs in solvent-based, water-based, and ultra-violet (UV) coatings were 37.28%, 9.88%, and 18.02%, respectively. For automotive coatings, the average content of the VOCs in water-based original equipment manufacturer (OEM) coating, solvent-based OEM coating, water-based refinishing coating, and solvent-based refinishing coating were 15.06%, 59.90%, 11.79%, and 54.50%, respectively. The content of the VOCs in different types of coatings varied substantially. The main components and OFP contributors were alcohols and ethers for water-based coatings, benzene series and esters for solvent-based coatings, and esters, alcohols, and ethers for UV coatings. The average value of the coating samples could meet the current mandatory national standards, but 12% of the solvent-based wood coating samples and 42% of the solvent-based OEM coating samples did not meet the standards. In addition, except for the benzene series of the water-based wood coatings, the contents of harmful substances in other coating samples were up to the standards.

Identification and analysis of odor-active compounds from Choerospondias axillaris (Roxb.) Burtt et Hill with different moisture content levels and lacquer treatments

The problem of indoor odors can greatly affect a room’s occupants. To identify odorants and comprehensively evaluate emissions from wooden materials, emissions and odors from Choerospondias axillaris (Roxb.) Burtt et Hill with different moisture content percentages and lacquer treatments were investigated in this study. Thermal desorption–gas chromatography–mass spectroscopy/olfactometry was used to analyze the release characteristics. In total, 11 key odor-active compounds were identified as moisture content gradually decreased, concentrating between 15 and 33 min. Total volatile organic compounds, total very volatile organic compounds, and total odor intensity decreased as moisture content decreased. In addition, 35 odor-active compounds, including aromatics, alkenes, aldehydes, esters, and alcohols, were identified in the odor control list. Polyurethane (PU), ultraviolet (UV), and waterborne coatings had a good inhibitory effect on eight odor characteristics, but some scents arose after lacquer treatment. For equilibrium moisture content, the major characteristics of Choerospondias axillaris were fragrant (9.4) and mint-like (3.0) compared with the fragrant (8.2), fruity (7.8), and pleasant (5.8) characteristics of PU coating; the flowery (5.9), fragrant (5.0), glue-like (4.3), and pineapple-like (4.3) characteristics of UV coating; and the antiseptic solution (3.6), fragrant (2.9), cigarette-like (2.8), and fruity (2.5) characteristics of waterborne coating. Based on multicomponent evaluation, a Choerospondias axillaris board with waterborne coating was suggested for use indoors.

UV coatings for wooden surfaces

Ultra violet (UV) radiation curing has emerged as a fast and environment friendly curing technique for coating on various surfaces (wood, metals, plastic & stone). Although, there are several UV curable coating formulations available in the international market, but these coatings have quite low viscosity and are not suitable for wooden surfaces as coatings tend to quickly get absorbed in to the porous structure of wood leading to slow curing. There is a need for designing coating formulations which are although sprayable, but have optimum viscosity so as to not get absorbed into the wooden surfaces. Besides, coatings have to have fast curing rate as well, so that while in process of curing they do not get absorbed in to the wood. Generally, UV curable coatings comprise of acrylate based oligomers (epoxy, polyurethane, and polyester), reactive diluents (mono-, di-, or polyfunctional glycidyl ether), photoinitiator (benzyl peroxide, phosphine oxide) and functional additives. These coating compositions are first applied on wooden surface and then exposed to UV radiation for curing. The photoinitiator dissociates on UV exposure to form free radicals, which initiate the polymerization of the oligomers and diluents, leading to the formation of a polymeric crosslinked network on the wooden surface. In the present study, sprayable coating compositions were designed based on epoxy acrylate that get cured within 10 s of UV exposure and exhibit excellent thermal and stain resistance properties.

A reactive hydrophobically modified ethoxylated urethane (HEUR) associative polymer bearing benzophenone terminal groups: Synthesis, thickening and photo-initiating reactivity

Hydrophobically modified ethoxylated urethanes (HEURs), as a representative class of associative polymers, are widely used as rheology modifiers in waterborne systems such as coatings, emulsions, inks etc. due to their unique associative network structure and finite relaxation behavior in solution. However, conventional HEURs are non-reactive and generally stay free in final cured films, which may induce some damages to the performance of the coatings. To solve the problem, a new concept of reactive HEUR has been proposed. That is, a reactive HEUR should bear reactive hydrophobic end-groups which can chemically crosslink with matrix resins during the curing process of waterborne coatings. In this work, with the help of the hydrogen abstraction photo-initiating reactivity of benzophenone (BP) group, a reactive HEUR (BPC11HEUR) end-functionalized by a photo-initiator BP moiety has been prepared. In aqueous solution, as demonstrated by steady shear measurement, an exponential increment of solution viscosity along with the increasing of polymer concentration (C) was found when C surpassed its critical percolation concentration (Cp ≈ 23.6 g/L). Besides, ultraviolet (UV) light induced photolysis in aqueous solution manifested a typical photochemical reaction behavior of BPC11HEUR polymer with a final photolysis degree (D) of approximate 78% after 300 s of irradiation. In situ 1H NMR and rheological measurements collectively revealed the efficient photo-initiating reactivity of BPC11HEUR for waterborne UV monomers or resins. Further, rheological measurements demonstrated that the emulsion zero/low shear viscosity can be greatly enhanced by ca. 50 folds for a commercially available waterborne UV polyurethane acrylate emulsion when the addition amount of BPC11HEUR varied from 0 to 1.0 wt%. These results shown that the reactive BPC11HEUR polymer can not only be used to efficiently modify the rheological properties of solutions or emulsions but also can chemically crosslink with waterborne UV acrylic monomers or resins by light irradiation. The work may be of interest for development of reactive HEURs used in waterborne UV coatings, inks, and adhesives, etc.

Performance of Wood Flooring UV Coatings Interfacial Modified by Nano-Silica

Cork flooring maintains the natural qualities of cork, showing the unique and elegant natural patterns, and also has series of advantages such as thermal insulation, sound insulation, moisture barrier, insulation, and no static. Ultraviolet (UV) curable coatings have no volatile organic compounds, little environmental pollution, fast curing, and are suitable for high speed automated production, which is the development of environmentally friendly wood floor coatings. In this paper, the UV-curable wooden coatings for floor were interfacially modified with nanosilica. The process parameters were optimized by orthogonal experiments, and the overall performance of wood flooring UV coating was obtained. The mechanical properties of the coating (hardness, adhesion and impact strength), resistance to liquid properties (resistance to aqueous sodium chloride solution, resistance to aqueous sodium hydroxide solution, resistance to alcohol, resistance to blue and black ink, resistance to sauce) and gloss were tested. It was found that wood flooring UV coating had good performance, hardness reached 3H, adhesion reached one grade, impact strength was 40 kgcm, and fluid-resistant performance (120 h) of coating reached one grade when the nanosilica content was 0.50%~0.70%, the drying time was 2 min, and medium pressure mercury UV lamp was 3. The gloss results showed that gloss of wood flooring UV coatings decreased with the increase of nanosilica content. When the nanosilica content was 0.50%~0.70%, the gloss value was in the vicinity of 35%, showing a matte gloss. This study provides new perspectives in wood flooring UV coating for industrial applications.

Enabling High Performance Mirrors for Astronomy with ALD

The technology of Atomic Layer Deposition holds promise to enable new classes of instruments and space missions a future flagship mission that can address both ultraviolet (UV) astrophysics and optical exoplanet science with a shared telescope. The technology path to a shared telescope requires the development of a mirror coating with high reflectance from 100 nm to 1000 nm, and low polarization effects (i.e., s-p phase shifts that can vary with angle of incidence across a primary and secondary mirror) in the optical range. Currently, UV coatings have low reflectance, and optical coatings have poor polarization properties for high-contrast coronagraph applications. In this paper we to take a first step toward solving both problems simultaneously by using ALD, taking advantage of the fact that ALD can potentially produce mirror coatings with denser layers than conventional coatings (hence better reflectance and durability), and ALD can potentially produce coatings with new composite materials (hence better control of polarization). We report here the results of our initial experiments with mirror coatings using ALD.

Effect of surface laminate type on the emission of volatile organic compounds from wood-based composite panels

As a part of understanding the influence of wood-based panels on indoor air quality of a building, this study examined the effects of laminate type on the emission of volatile organic compounds (VOCs) such as formaldehyde, toluene, and total VOCs (TVOCs) from particle board (PB) and medium density fiberboard (MDF) panels, using a 20-L small chamber method. Five different types of surface laminates, including three types of surface overlays such as low pressure laminate (LPL), poly(vinyl chloride) (PVC) film, and urethane coated paper (UCP), as well as two types of surfaces coatings, i.e. direct coating (DC) and ultra-violet coating (UVC) were applied to the veneer bonded to a surface of PB and MDF panels that were of different grades with respect to formaldehyde emission (FE) such as E 0, E 1, and E 2 before surface lamination. As expected, the FE grade strongly affected the FE of panels, regardless of types of panel and laminate. All types of surface laminations dramatically reduced the FE compared to the control. However, the surface laminations by overlay significantly decreased the emission of TVOCs and toluene while both types of surface coatings greatly increased the emission of TVOCs and toluene. In particular, styrene was the main component of TVOCs from the DC sample (about 87%), while toluene was the main species of TVOCs from the UVC sample (about 73%). When two different ways of sample preparation (i.e., single- or all-surface exposure) were compared, the FE of the MDF sample was influenced by the surface exposure type. But TVOCs and toluene emissions were independent of the FE grade and the sample preparation. These results suggest that a proper selection of the surface laminate for wood panels has a significant impact on indoor air quality of a building.

투명방음판의 품질기준 설정에 관한 연구(2) - 음향 특성 및 내후성 평가

Transparent noise barrier panels have the advantages of transmitting light to nearby residents and allowing drivers to orientate themselves by providing views of the surrounding area. To develop guidelines on quality criteria for transparent soundproof panels, their sound transmission loss and weatherability were experimentally investigated. In Korea, the sound transmission loss of noise barrier panels should be more than 25 dB at 500 Hz and 30 dB at 1000 Hz. The transmission loss tests of transparent panels were performed in accordance with KS F 2808. Typically, plastic materials suffer from color changes when exposed to ultraviolet(UV) light over extended periods. Therefore, weathering of plastics is one of the most important properties for outdoor applications. Protection against UV radiation and weathering is usually accomplished by using UV stabilizer additives or coatings. Transparent materials for soundproof panels were examined through accelerated weathering tests and their weathering resistances were evaluated from changes in yellowness index.

Epoxy acrylate UV/PU dual‐cured wood coatings

AbstractFor improving the finishing performances of complicated three‐dimensional coated wood products (e.g., furniture) with some shadow zones in the absence of ultraviolet (UV) light, resulting in incomplete curing of UV coatings, the aim of this study was to investigate the characteristics and effects of curing process on the properties of epoxy acrylate UV/PU dual‐cured resin for wood coatings when compared with traditional UV and polyurethane (PU) coatings. The epoxy acrylate oligomer was synthesized for providing a double bond of acryloyl group and a secondary hydroxyl group. The UV/PU dual‐cured coating was formulated with epoxy acrylate resin/tripropylene glycol diacrylate (TPGDA) monomer by the weight ratio of 80/20, 3% dosage of benzil dimethyl ketal as a photoinitiator, and the NCO/OH mole ratio of 1.0. The aromatic polymeric diphenylmethane diisocyanate was used as a hardener. The films of the dual‐cured coating, obtained from UV‐cured or room temperature‐cured process, showed an excellent tensile strength, elongation at break, impact resistance, and lightfastness when compared with traditional UV and PU coatings; especially, the adhesion of UV/PU dual‐cured coating by UV‐cured process was better than that of traditional UV coating. It can therefore be concluded that the epoxy acrylate oligomer‐based dual‐cured coating could readily be used for complicated wood products finishing. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

UV Absorber Permanence and Coating Lifetimes

Abstract Delamination is the ultimate failure mechanism of a coating. Delamination times often are closely related to the dose of ultraviolet (UV) radiation reaching the substrate or primer, and this dose is related to the UV absorbing capability of the overlying coating. Organic UV absorbers are not permanent, and their photodegradation is an important factor in determining coating lifetime. The kinetics and some of the chemistry of UV absorber photodegradation have been studied extensively over the past decade and applied to coating lifetime prediction. Rates of UV absorber loss vary widely and are highly dependent on the coating matrix, so must be determined on a case-by-case basis. Simple zero- or first-order kinetic schemes give rates that are dependent on the initial absorbance of the sample. This paper discusses a more reliable kinetic equation and applies the rate constant to prediction of delamination times.

Siloxane modified cycloaliphatic epoxide UV coatings

Tetraethyl orthosilicate (TEOS) functionalized caprolactone diol and triol were used to modify cycloaliphatic diepoxide/caprolactone polyol cationic ultraviolet (UV) curable coatings. Two levels of the cycloaliphatic diepoxide (60 and 70 wt.%) were used in the coating formulations. Siloxane functionalized polyols were added to the cycloaliphatic diepoxide/caprolactone polyol coating formulations as a replacement of the parent caprolactone polyols. To monitor the potlife, the viscosity of the coating formulations was measured as a function of storage time. The coatings were evaluated in terms of Tukon hardness, tensile properties, wet pull-off adhesion, glass transition temperature, gloss, and dark cure. The addition of the siloxane functionalized polyols into the coating formulations significantly increased the glass transition temperature and Tukon hardness. Wet adhesion and gloss were also improved. The addition of the siloxane functionalized polyols, however, reduced the potlife of the coatings.

Effect of siloxane functionalized caprolactone polyols on photocurable epoxy coatings

Cationic ultraviolet (UV) coatings were formulated using a cycloaliphatic diepoxide (3,4-epoxycyclohexyl methyl-3′, 4-′epoxycyclohexane carboxylate) with siloxane modified caprolactone polyols. Both di- and tri-TEOS (tetraethyl orthosilicate) functionalized caprolactone polyols were used to modify the UV coatings. The resulting coatings were cured and evaluated in terms of pencil hardness, MEK double rubs, crosshatch/pull-off adhesion, and reverse impact resistance. Addition of the siloxane-functionalized polyols into the caprolactone polyol/cycloaliphatic diepoxide coating formulations improved pencil hardness, MEK double rubs, and enhanced toughness of the coatings. When the addition of siloxane-functionalized polyols was less than 25 wt%, the resulting coatings had significantly increased adhesion. In addition, modification of the coatings with the siloxane-functionalized polyols also reduced surface tension and improved film formation with reduced levels of surface wetting agent. Without the modification, the coatings exhibited a poor balance of hardness and adhesion.

UV-curable paints & coatings: A practical application of quantum mechanics

+ost manufacturing operations require a paint or coatM ing treatment of some type (Le., protective, identification, decorative). This is especially true for metal finishing where in many cases acceptance of the part by the customer is predicated upon the appearance of the part. Compliance with ever tightening environmental legislation will sooner or later be an issue for most all manufacturers who incorporate a coating operation. Consequently, manufacturers must seek and implement new technology that will not only provide them with a competitive advantage but will also comply with environmental legislation, simplify production, and enhance product quality. One coating technology that professes such a winwin scenario is ultraviolet (UV) coating technology. This article will, in addition to providing an overview of typical features and benefits of UV coatings, touch upon basic quantum mechanical theory behind the technology in order to understand how such performance, features, and benefits are possible.