Effect of nano‐TiO2 on MP‐25 resin

MP‐25 resin is a chlorine‐containing polymer widely used in coatings. The effects of two types of nano‐TiO₂ (P‐25 and RM301 LP) on MP‐25 were studied with saline immersion, UV irradiation, and electrochemical impedance spectroscopy. UV irradiation was evaluated in terms of gloss change and X‐ray photoelectron spectroscopy (XPS). The results indicate that, compared to pigment R‐930 TiO₂, P‐25 reduced the immersion resistance and accelerated UV aging of the MP‐25 coating, whereas RM301 LP showed the opposite effects. XPS analysis showed that MP‐25 resin degraded under UV irradiation via dechlorination and C? C bond breakage, similarly to poly(vinyl chloride), but RM301 LP could inhibit the aging of MP‐25 to a certain extent. A skin effect of oxygen and chlorine was identified in MP‐25 resin by XPS. RM301 LP could improve the impedance of the MP‐25 coating because of its excellent fill capacity. Hence, rutile nano‐TiO₂ RM301 LP represents an excellent additive for MP‐25 resin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation,property characterization and UV‐converting application of poly(conjugated azomethine‐urethane)/hydroxyl polyacrylate resin

A functional polyurethane coating with ultraviolet (UV) rays converting ability of changing higher energy UV rays into lower ones was prepared from poly(conjugated azomethine‐urethane) (CAUP) reacting with hydroxyl polyacrylate resin (HPAR). As an oligomeric isocyanate, CAUP was prepared in a reaction of toluene‐2,4‐diisocyanate with N,N′‐bis(4‐hydroxyl‐3‐methoxybenzylidene)‐o, m or p‐diaminobenzene that was synthesized from vanillin and o‐phenylenediamine or m‐phenylenediamine or p‐phenylenediamine. Fourier transform infrared spectroscopy, ¹H‐NMR, UV–vis, and fluorescence spectra were used to characterize those synthesized products and HPAR/CAUP films. UV‐converting abilities of HPAR/CAUP films had been demonstrated by natural exposure to ageing and the fluorescence emission spectra of HPAR/CAUP films and CAUP solutions. Red‐shift phenomena in the fluorescence emission spectra were due to molecule aggregations and stacks caused by intramolecular and intermolecular interactions such as hydrogen bonding effects. Dynamic mechanical thermal analysis and thermogravimetric analysis techniques were employed to study their mechanical and thermal properties of HPAR/CAUP films. The films exhibited excellent mechanical properties and owned high glass transition temperatures over 97.0°C, and their maximum thermal degradation temperatures were about 176.0°C. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

An improved accelerated weathering protocol to anticipate Florida exposure behavior of coatings

A new accelerated weathering protocol has been developed which closely replicates the performance of automotive and aerospace coating systems exposed in South Florida. IR spectroscopy was used to verify that the chemical composition changes that occurred during accelerated weathering in devices with a glass filter that produced a high fidelity reproduction of sunlight’s UV spectrum matched those that occurred during natural weathering. Gravimetric water absorption measurements were used to tune the volume of water absorption during accelerated weathering to match that which occurred during natural weathering in South Florida. The frequency of water exposure was then scaled to the appropriate UV dose. A variety of coating systems were used to verify the correlation between the physical failures observed in the accelerated weathering protocol and natural weathering in South Florida. The new accelerated weathering protocol correctly reproduced gloss loss, delamination, cracking, blistering, and good performance in a variety of diverse coating systems. For automotive basecoat/clearcoat paint systems, the new weathering protocol shows significant acceleration over both Florida and previous accelerated weathering tests. For monocoat aerospace systems, the new weathering protocol showed less acceleration than for automotive coatings, but was still an improvement over previous accelerated tests and was faster than Florida exposure.     

Preparation of Polyetheramine‐Grafted Lignin and Its Application in UV‐Resistant Polyurea Coatings

Lignin‐containing polyurea coating with good ultraviolet (UV) resistance is prepared by partially substituting polyetheramine with enzymatic hydrolysis lignin. Lignin is first grafted by polyetheramine chains via Mannich reaction, which improves its interfacial compatibility with polyurea matrix. The influences of the modified lignin on the chemical and corrosion resistance, UV‐aging property, and thermal stability of the polyurea coatings are studied. It is demonstrated that lignin‐containing polyurea coatings exhibit excellent UV‐aging properties. Aminating lignin with polyetheramine improves its dispersion in the polymer matrix. This work offers a novel method for the high‐value utilization of biomass lignin in anti‐UV polyurea coatings.     

水性聚偏氟乙烯型反射隔热涂层的耐久性研究

研究了在酸、碱、盐和 UV辐照等环境作用下水性聚偏氟乙烯型（ PVDF）反射隔热涂层性 能的时变规律。使用扫描电镜（ SEM）和能谱分析表征了涂层微观形貌及断面中的氟元素分布， 对涂层在经各类环境作用前后的明度、光泽、色差、力学性能和反射隔热性能进行了测试，并使用 ATR-FTIR对表面涂层的官能团变化进行了分析。结果表明：氟元素在涂层树脂基体中的垂向分布较均匀； 56 d UV处理会提升涂层光泽；经酸、盐和 UV处理后，涂层明度未见明显变化且色差较小，涂层断裂伸长率降低且抗拉强度提升，最高达 8.4 MPa，反射隔热性能指标未见明显变化；碱处理后的涂层出现明显的色差和明度下降，涂层变脆且抗拉强度下降，同时太阳光反射比由 0.70降至 0.65。ATR-FTIR分析结果表明：涂层的耐酸、盐和 UV能力较强，但在碱性条件下存在含氟组分的降解破坏情况。     

高速动车组风挡橡胶漆耐老化性能比较研究

选择了不同厂家的风挡橡胶涂料体系,制备涂层样板,从而进行人工加速紫外老化试验。通过测试各种涂层体系样板的外观、光泽度值、色差、明暗度、失光率等参数,研究了各种参数随老化时间的变化规律,评价了各种涂料体系的耐老化性能,进而为研究各种涂料体系的耐老化性能奠定了基础。     

Synthesis and characterization of triglyceride‐based polyols and tack‐free coatings via the air oxidation of soy oil

The effect of time and temperature on the air oxidation of soybean oil in the absence of catalysts or added initiators was investigated. It was possible to divide the air oxidation of soybean oil into three regimes. The first regime of air oxidation resulted in insignificant change in the hydroxyl number. During this regime, it was proposed that natural antioxidants, which are present in raw soybean oil, were consumed and peroxide formation occurred. A drastic increase in hydroxyl number due to the formation and subsequent decomposition of peroxides marked the second regime of air oxidation. In the third regime of air oxidation, free radical crosslinking of the soybean oil occurred, and an insoluble gel was formed. The three regimes of air oxidation were used as a guide for the preparation of soy‐based polyols and crosslinked polymers. Crosslinked, tack‐free coatings were prepared from a metal catalyzed oxidation of soybean oil, where soybean oil and ambient oxygen were the only reactants. Higher temperatures (125°C) were more efficient than lower (50°C) for obtaining high gel fractions and tack‐free coatings. Cure of the coatings was expedited with exposure of the coating to UV irradiation after initial heating. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 690–697, 2006     

氙灯老化与自然曝晒测试所得颜料耐候性的相关性

比较了自然户外曝晒与氙灯加速老化测试之间的结果,试验表明,其间存在较好的相关性,用试验室加速老化试验来评估颜料和涂料体系的耐久性是可行的,并且是可靠的。     

Enhancing exterior durability of jack pine by photo-stabilization of acrylic polyurethane coating using bark extract. Part 1: Effect of UV on color change and ATR–FT-IR analysis

Heat-treated wood is a value-added product but its exposure to various environmental factors leads to discoloration of wood surface due to the photochemical reactions. Discoloration has become an important economic problem for wood industries since product specifications are now more demanding. In addition, stricter environmental legislations necessitate the development of environmentally friendly transparent coatings with minimal use of chemicals which balances aesthetic and protection. In this study, the acrylic polyurethane coating was improved with the addition of natural antioxidant (bark extract) and lignin stabilizer alone or in combination to enhance the resistance of this coating to different weathering factors. An accelerated aging test was conducted with the aim of comparing the acrylic polyurethane coatings containing different additives with the commercially available pigmented solvent borne coating used by industry and organic UV absorbers. The modifications in chemical structure of coatings were characterized by ATR–FT-IR analysis. The color change data showed that the coating containing bark extract was the most effective and performed better than the industrial coating. However, the visual assessment showed that the coating containing bark extract and lignin stabilizer had the best performance. FT-IR analyses suggested that the chain scission reaction took place throughout the weathering but its effect was not significant for any of the coatings.     

Correlation between natural exposure and artificial ageing test for typical marine coating systems

Natural exposure test at Sanya and artificial ageing test were carried out for four kinds of typical marine coating system, respectively. The gloss, surface morphology, coating impedance, and infrared spectra of the coatings were measured with methods of SEM, EIS, and FT‐IR. The correlation between results from artificial ageing test and natural exposure test was discussed. The fluorocarbon paint showed longer ability to remain high gloss than polyurethane paint. The xenon lamp ageing test and natural exposure test led to similar changes in surface morphology of the coatings. For polyurethane paint under both tests, with extended testing time micropores and cracks occurred gradually on the surface, meantime the coating gloss decreased. The increase of the defect area corresponded well to the decrease of the coating gloss, suggesting that the degradation extent of the coating surface could be reflected by the gloss measurement. The rank correlation study showed that the results by 60 d, 150 d, 300 d, 360 d, and 450 d natural exposure, respectively, were very close to those by 228 h, 443 h, 841 h, 1958 h, and 4013 h artificial ageing test. Hence, the artificial xenon lamp ageing test may be used to simulate natural exposure test at Sanya. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43893.     

Accelerated weathering performance of Scots pine preimpregnated with copper‐based chemicals before varnish coating Part:1 coated with cellulosic and polyurethane varnishes

This study aimed to determine the effect of accelerated weathering on gloss, surface hardness and colour changes of Scots pine (Pinus sylvestris L.). Test samples were impregnated with Adolit KD‐5, Wolmanit CX‐8 and Celcure AC‐500 covered with cellulosic and polyurethane varnishes. The results showed that the values of surface hardness and gloss increased after accelerated weathering. While the surface hardness of Scots pine was increased for impregnated and polyurethane‐coated varnish, it decreased for impregnated and cellulosic varnish‐coated Scots pine after 1000 hours of accelerated weathering exposure. Copper‐based chemical impregnation and varnish coating developed the gloss of Scots pine specimens relative to the surface characteristics observed in single‐coated Scots pine specimens. While the most appropriate chemical was Celcure AC‐500 for surface hardness, it was Adolit KD‐5 for the gloss of Scots pine after 1000 hours of accelerated weathering exposure. Wood specimens impregnated prior to the application of varnish were more effective in stabilising the colour of Scots pine than Scots pine only coated with varnish. Polyurethane varnish‐treated Scots pine showed better colour stability for each partial and total accelerated weathering exposure period. The total colour changes were lowest for polyurethane varnish‐coated Scots pine impregnated with Celcure AC‐500 after 1000 hours of accelerated weathering exposure.     

Behavior of UV‐cured print inks on LDPE and PBAT/TPS blend substrates during curing,postcuring, and accelerated degradation

During radiation curing, a reactive formulation is converted into a highly crosslinked coating film by means of polymerization reactions. This three‐dimensional (3D) network is resistant to external degrading factors as it cannot be undone by any physical–chemical means. In this study, various ultraviolet (UV)‐curable ink formulations with different pigments were developed. The behavior of the UV‐curable inks was evaluated during UV curing in a photocalorimeter or in a UV tunnel. Inks were exposed to accelerated aging in an accelerated weathering chamber and their physical–chemical properties were investigated. The presence of residual fractions of unreacted species trapped in the 3D network formed during UV curing interferes with the degradation of the main structure during exposure in the weathering chamber. The ink formulations that did not easily absorb UV light increased in gloss and hardness, indicating that residual crosslinking is taking place at the same time that degradation is occurring. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41116.     

Effect of hyperbranched acrylates on UV‐curable soy‐based biorenewable coatings

Utilization of biorenewable components in UV‐curable coating formulations is both economically and environmentally beneficial, particularly when compared to their petrochemical‐based counterparts. To produce UV‐curable coatings of high biorenewable content with enhanced performance, acrylated epoxidized soybean oil (ASBO) was combined with biorenewable reactive diluent tetrahydrofufuryl acrylate, adhesion promoters, photoinitiator and hyperbranched acrylates (HBAs) as synthetic tougheners. The HBAs were found to impart high functionality and low viscosity, thus increasing crosslinking in the coating network and improving mechanical and thermal properties such as film hardness, adhesion, solvent resistance, impact resistance, tensile modulus and toughness, glass transition temperature and thermal stability. Real‐time Fourier transform infrared spectroscopy showed decreased acrylate conversion when compared with a reference formulation without HBAs, which was attributed to earlier coating network vitrification during UV irradiation. ASBO‐based coatings were also thermally annealed to allow further reaction of unreacted components in the vitrified network. As a result, coating properties were further improved. Overall, the addition of HBAs as synthetic tougheners to UV‐curable ASBO‐based biorenewable coating systems was shown to greatly improve the corresponding coating properties. Copyright © 2010 Society of Chemical Industry     

A positive‐working photosensitive polyimide based on thermal cross‐linking and acidolytic cleavage

A novel positive‐working photosensitive polyimide (PSPI) based on a poly(hydroxyimide) (PHI), a crosslinking agent having vinyl ether groups, and a photoacid generator (PAG) was prepared. The PHI as a base resin of the three‐component PSPI was synthesized from 4,4′‐oxydiphthalic anhydride and 2,2′‐bis(3‐amino‐4‐hydroxyphenyl)hexafluoropropane through ring‐opening polymerization and subsequent thermal cyclization. 2,2′‐bis(4‐(2‐(vinyloxy)ethoxy)phenyl)propane (BPA‐DEVE) was used as a vinylether compound and diphenyliodonium 5‐hydroxynaphthalene‐1‐sulfonate was used as a PAG. The phenolic hydroxyl groups of the PHI and the vinyl ether groups of BPA‐DEVE are thermally crosslinked with acetal structures during prebake step, and the crosslinked PHI becomes completely insoluble in an aqueous basic solution. Upon exposure to UV light (365 nm) and subsequent postexposure bake (PEB), a strong acid generated from the PAG cleaves the crosslinked structures, and the exposed area is effectively solubilized in the alkaline developer. The dissolution behavior of the PSPI containing each 11.5 wt % of BPA‐DEVE and of the PAG was studied after UV exposure (365 nm) and PEB. It was found that the difference in dissolution rates between exposed and unexposed areas was enough to get high resolution. A fine positive pattern with a resolution of 5 μm in a 3.7‐μm‐thick film was obtained from the three‐component PSPI. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Surface properties of polyurethane powder lacquers modified with polysiloxane‐methacrylic core‐shell nanoparticles

Non‐ and core‐shell nanoparticles‐containing polyurethane‐based powder coating systems, crosslinked with allophanate bonds containing polyisocyanates were examined. The surface structure of the powder coatings were investigated with a confocal microscopy and polarized optical microscopy (POM) using reflected light. The three‐dimensional surface topography and the values of surface roughness were determined. The surface structure was correlated with the chemical structure of the coatings and macroscopic surface behavior: surface free energy and gloss. These experimental results led to a better understanding of the development of surface topography and morphology and provide valuable information for the development of new polyurethane powder coating systems. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Performance of polyester and modified polyester coil coatings exposed in different environments with high UV radiation

Coil coating is a continuous strip coating technology, which enjoyed rapid growth. It provides a cost-effective method of applying a coating to a metal substrate with a low solvent emission, and nowadays paints of different nature are applied this way on a range of metal substrates, for a large variety of products and uses.

Coil coatings can be more or less degraded by high UV radiation. However, differences in distribution of light intensity as a function of wavelength between exposure environments, can lead to significant differences in the degradation results, depending on coating nature. In this work, the behaviour of polyester and silicone polyester coatings exposed in three different high UV environments (natural atmosphere and two accelerated UV tests), was studied. Coatings of two different colours (blue and brown) were considered for each paint system. Colour change, gloss and chalking measurements and, visual inspections of coating defects were carried out. In order to explain their corresponding performance, chemical changes on coil coated exposed surfaces were studied by to Fourier transform infrared spectroscopy equipped with a photoacustic detector (PAS/FTIR).     

Weathering modification of acrylic emulsion by introducing UV absorbing groups

A new kind of UV-absorbing silicon-fluorinated acrylic emulsion was prepared by emulsion polymerization with 4-allyloxy-2-hydroxybenzophenone, 3-methacryloxypropyltrimethoxysilane (MPS) and hexafluorobutyl methacrylate (HFMA) as functional monomers. The emulsion and its coating were characterized by transmission electron microscope, Fourier transform infrared spectrum (FTIR), X-ray photoelectron spectroscopy, ultraviolet absorption spectrum,thermo-gravimetric analysis, water contact angle (CA), and artificial accelerated aging test. The results indicated that the emulsion with core-shell structure was synthesized and showed prominent absorption peaks at 320 and 350 nm. The water CA of the coating was increased from 70.2° to 86.7° because of the incorporated HFMAs and MPSs. Both of the initial and final decomposition temperatures of the coating were increased by more than 20°C compared with those of the unmodified coating. After 10 days of accelerated aging, the color difference (ΔE) and rate of loss of gloss (ΔG) were only 2.78% and 5.22%, while those of the unmodified coating were as high as 22.94% and 78.57%, respectively. Because of the UV absorbers were incorporated by chemical reaction, the new coating had a more durable and effective anti-ultraviolet performance compared with the coatings the UV absorbers were introduced by physical blending.     

Stress photo‐oxidative aging behaviour of polyamide 6

The long‐term stress accelerating aging behaviour of polyamide 6 (PA6) was studied by exposure to UV irradiation. The aging behaviour and mechanism were investigated in terms of creep behaviour, mechanical properties, chemical structure, crystallization and orientation behaviour. It was found that the creep deformation of PA6 under stress/UV irradiation was lower than that of the sample aging only under stress, resulting from crosslinking and low mobility of molecules under UV irradiation. The tensile strength of PA6 under stress and stress/UV irradiation substantially increased at the primary aging stage due to stress‐induced molecular orientation. The oxidation of PA6 may also be inhibited by orientation, leading to a relatively low content of carboxylic groups. Under UV irradiation, stress accelerates the degradation of PA6, resulting in strengthening UV absorption due to formation of isolated carbonyl groups. The melt temperature and crystallinity both showed an increase with time, which were much higher for the sample aged under stress/UV irradiation than for that aged only under UV irradiation. Wide‐angle X‐ray diffraction analysis also showed that the orientation factor and crystallinity of PA6 increased with aging time before 16 days, indicating a clear orientation and crystallization of molecules induced by stress. The UV‐induced crosslinking reduced the mobility of PA6 chains, resulting in a lower crystallinity and orientation factor of the sample aged under stress/UV irradiation compared with that under stress aging only. Copyright © 2011 Society of Chemical Industry     

UV curing and matting of acrylate nanocomposite coatings by 172 nm excimer irradiation

For UV-curable acrylate coatings reinforced by silica nanoparticles, the effect of 172 nm excimer irradiation on the surface roughness has been studied. A dual UV lamp set-up consisting of a 172 nm excimer lamp and a mercury arc lamp allowed obtaining gloss levels down to 0.5 units (at 60°) depending on the acrylate formulation and curing conditions. Moreover, UV matt-finished sample showed enhanced surface hardness and increased chemical resistance. It is assumed that 172 nm excimer irradiation resulted in a higher network density via additional cross-linking reactions.To study the depth profile of acrylate conversion for coatings cured by the combination of a 172 nm excimer lamp (accountable for surface curing) and a mercury arc lamp (responsible for through curing), FTIR microscopy as well as (Ge)ATR-FTIR having an IR penetration depth of less than 0.5 μm have been applied. Providing the presence of a photoinitiator as well as the absence of oxygen inhibition, similar degrees of double bond conversion of about 90% were observed on the entire area of the cross-section of the coating, i.e. the wavelength of UV irradiation was found to have no significant impact on acrylate conversion.     

Epoxy acrylate UV/PU dual‐cured wood coatings

For 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