Properties Of UV-cured Coatings Research Articles

Coating Properties of UV Curable Coatings on Natural Nails: Impact Evaluation of 5 Different Acrylate Monomers

Compositions on natural nails mostly contain acrylic monomers, more often 2-hydroxyethyl methacrylate (HEMA). These systems have been considered to be a potent sensitizer in contact with the skin. The purpose of the study was to compare five acrylic monomers: HEMA (hydroxyethyl methacrylate), HPMA (hydroxypropyl methacrylate), IBOMA (isobornyl methacrylate), MEP (methacryloylethylphosphate) and TMPTMA (trimethylpropane trimethacrylate) to find the substitute to HEMA. In this study, we explored the rheological and polymerization properties of uncured systems containing five acrylate monomers. Mechanical and adhesion properties were evaluated of cured compositions. Optimal criteria of compositions and cured coatings were defined, and tests were performed to find the most appropriate composition. HEMA is the most widely used acrylic monomer in nail coatings due to its outstanding characteristics: high reactivity (temperature reached at polymerization Tmax = 95 °C), good adhesion (1.5 MPa on glass and aluminum), high solubility in acetone (ms = 22 %). The greatest potential to substitute HEMA has monomer HPMA, due to its good abrasion resistance (G = 66 GU after abrasion), high reactivity (Tmax = 88 °C), and adhesion (1.5 MPa on glass and on aluminum). The polymerization process of a composition containing MEP was the fastest and reached the highest maximum temperature during polymerization process (Tmax = 115 °C) and great adhesion (2.5 MPa). The best surface abrasion resistance (G = 76 GU after abrasion) was reached for coatings containing TMPTMA.

자동차 내장 플라스틱 파트 코팅을 위한 UV 경화형 코팅액의 가교와 표면의 기계적 물성과의 상관관계

자동차 내장 플라스틱 파트 코팅을 위한 UV 경화형 코팅액의 가교와 표면의 기계적 물성과의 상관관계

Polyurethane modified epoxy acrylate resins containing ε-caprolactone unit

Epoxy acrylate resins modified by polyurethane with excellent mechanical properties play a crucial role in UV-curable coatings, but the high viscosity limits their further applications in 3D printing, electronic packaging material. In this work, a series of polyurethane modified epoxy acrylate resins containing various ε-caprolactone unit content were successfully synthesized to reduce the viscosity of polyurethane modified epoxy acrylate resins. The chemical structure and molecular weight of the prepared resins were characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR) and gel permeation chromatography (GPC), respectively. The influences of ε-caprolactone unit on the viscosity of resins and double bond conversion of cured films were studied. The dynamic thermomechanical properties, mechanical properties, thermal stability and basic properties of UV curable coatings were also evaluated. The results show that the viscosity of resins is reduced by two orders of magnitude. As the ε-caprolactone unit content increased, the adhesive force increased from 0B to 5B according to ASTM D3359, while the glass transition temperatures (Tg) of films and pencil hardness were slightly lower than those of the conventional polyurethane modified epoxy acrylate resins. In summary the introduction of ε-caprolactone unit in the side chain enables the preparation of polyurethane modified epoxy acrylate resin with ultralow viscosity as well as a more comprehensive adhesive and impact force performance.

Synthesis of acrylated cardanol diphenyl phosphate for UV curable flame-retardant coating application

Acrylated cardanol diphenyl phosphate (ACP) was synthesized via epoxidation of unsaturation in long side chains of cardanol, followed by acrylation of epoxidized cardanol and, phosphorylation of acrylated cardanol. The chemical structure of synthesized products was confirmed using Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR and, 31P NMR) and gel permeation chromatography technique (GPC) respectively. The effect of increasing content of ACP into UA oligomer on viscosity of coating formulations was studied using rheometer analysis. The properties of UV curable coatings were determined by differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD) and, thermogravimetric analysis (TGA). The flammability of UV cured coatings were analyzed by limiting oxygen index (LOI) and UL-94 vertical burning test. TGA result shows that the introduction of ACP into UA oligomer promotes degradation of UA oligomer and enhances the char formation. The structure of obtained char residues was further investigated from scanning electron microscopy (SEM), FTIR and Raman spectroscopy analysis. These cardanol based reactive diluent is promising candidates for UV flame retardant UV curable coatings because of their unique structure contains rigid benzene rings, phosphate moiety, polar hydroxyl groups, and long aliphatic chains.

Effect of temperature on mechanical properties and formability of coatings for pre-coated metal

ABSTRACTTo expand their applications, UV-curable coatings for pre-coated metal (PCM) require high flexibility and stiffness for formability and hardness, respectively. However, it is difficult to satisfy both properties of coatings. Therefore, this study was focused on each factor which affects the properties of UV-cured coatings or PCM. The curing conversion of UV-cured coatings was improved in oxygen-free atmosphere. The optimum UV irradiation for curing was 1500 mJ/cm2. Adhesion of coatings and formability of PCMs were characterized by cross-cut test and cross-cut erichsen test, respectively at different temperatures. The results showed that the formability was much improved at an elevated temperature due to the increased flexibility.

Studying the effect of hyperbranched polymer modification on the kinetics of curing reactions and physical/mechanical properties of UV-curable coatings

Abstract A polyester-amide based hyperbranched polymer with hydroxyl end-groups is modified by the aid of acrylic functionalities. Two levels of modification, i.e. 40% and 65%, are considered. The unmodified hyperbranched polymer and the modified ones are added to UV-curable monomeric and oligomeric systems. Rheology measurements are conducted to investigate the effects of hyperbranched polymer on the rheological behavior. In order to assess the curing kinetics and physical/mechanical characteristics of the samples, photo-DSC and DMA experiments are exploited, respectively. The effect of viscosity and number of UV-curable functionalities of the hyperbranched polymer on the curing level and kinetics of the curing reactions are discussed. Dynamic mechanical analysis shows that the addition of hyperbranched polymer in the formulation increases a 25% in storage modulus of the glassy region and cross-linking density of the UV-curable coating. Furthermore, it is also seen that the existence of the hyperbranched polymer increases the viscosity of Trimethylolpropane triacrylate (TMPTA)-based system while it is decreasing the viscosity of oligomeric-based of the epoxy di-acrylate system. It is obtained that the hyperbranched polymer makes the curing level in the monomeric and the oligomeric system, improve up to 15% and 10% correspondingly. It is also observed that T g s of the coatings containing the hyperbranched polymer increases up to 5.9 °C.

Grafting of hyperbranched polymer onto the nanosilica surface and their effect on the properties of UV-curable coatings

The nanosilica is first treated with 3-mercaptopropyl trimethoxysilane (MPTMS) to introduce mercapto groups as growth points, and then hyperbranched polymer is grafted on the nanosilica surface via repeated step of thiol-ene click reaction between the acrylate double bond of trimethylolpropane triacrylate (TMPTA) and mercapto groups of trimethylolpropane tris 3-mercaptopropionate (Trithiol). FTIR results confirm that the grafting procedure is feasible, and TGA results indicate the grafting ratio is as high as 45.0 %. The curing kinetic, monitored by photo-DSC, shows that both terminal acrylate double bonds and mercapto groups can accelerate the curing speed of the UV-curing organic–inorganic hybrid coatings. The mechanical and physical properties of UV-curable hybrid coatings containing modified nanosilica at different generations are also investigated.

Effect of reactive diluent on physicochemical and thermal properties of UV-curable alkyd coatings

UV-curable coating has gained popularity in many industries as an efficient yet environmentally friendly coating. This article presents a comprehensive study on the effect of different reactive diluents on the film properties of UV-curable coating. Palm-oil-based alkyd was chosen as the resin in this work due to its compatibility with many different types of reactive diluents. A total of four different types of commercially available reactive diluents were used in this study, and the effects on the physicochemical and thermal properties of the coatings were investigated. The Flynn–Wall–Ozawa approach was employed to investigate the thermal stability of the coatings with respect to the activation energy of decomposition, Ed. The results show that some of the coatings formulated with different types of reactive diluents exhibit different properties, such as different tack-free time, pencil hardness, film adhesion, and thermal stability. The factors contributing to the observed differences include the functionality and reactivity of –C=C– in the reactive diluents.

Surface modification of nanosilica with 3-mercaptopropyl trimethoxysilane and investigation of its effect on the properties of UV curable coatings

This paper describes surface modification of commercial nanosilica with 3-mercaptopropyl trimethoxysilane (MPTMS) and its effect on the properties of UV curable coatings. The mercapto groups were grafted onto nanosilica surface by a condensation of the surface Si–OH with the hydrolysized Si–OH of MPTMS. Fourier transform infrared spectroscopy, thermal gravimetric analysis, and particle size distribution were employed to characterize nanosilica and modified nanosilica. It was demonstrated that the mercapto groups were successfully grafted onto the nanosilica surface with the grafting ratio of 16.8% and the mercapto groups content of 0.9 mmol/g. The dispersion and self-aggregation of nanosilica in UV curable coatings were improved significantly. The photopolymerization kinetics of UV curable coatings, containing various amounts of nanosilica and modified nanosilica, were evaluated by the photo differential scanning calorimetry technique. This indicated that nanosilica both before and after modification decreased UV curing speed and ultimate percentage conversion; however, in comparison with the coatings containing unmodified nanosilica, the coatings containing modified nanosilica exhibited higher curing speeds and conversion ratios. It can be ascribed that the mercapto groups on the nanosilica surface reduced oxygen inhibition during the UV curing process via the thiol–ene click reaction. The mechanical properties of UV curable coatings were also compared.

Study of the effect of organically functionalized silica nanoparticles on the properties of UV curable acrylic coatings

In this work the properties of UV curable coatings were improved modifying the polymeric matrix adding properly functionalized silica inorganic nanoparticles. Mild steel sheets were used as substrate. Pre-formed silica nanoparticles, prepared by sol–gel chemistry from methyltriethoxysilane (MTES) and methacryloxypropyltrimethoxysilane (MPTMS) precursors, were dispersed into UV curable acrylic oligomers: by irradiation a polymeric matrix embedding the nanoparticles was obtained. Unfilled UV cured coatings were also produced for comparison. The DSC measurements revealed different thermal stabilities among the samples, depending on the presence of the functionalized nanoparticles. The barrier properties (investigated by means of electrochemical impedance spectroscopy, EIS) were demonstrated to be strongly affected by the presence of the nanoparticles. In particular, a proper functionalization of the silica nanoparticles leads to noticeable improvement of the barrier properties of the coatings against ions permeation. The effect of the functionalized nanoparticles on the coating properties was also investigated performing water vapor diffusion measurements through the different coatings. The experimental measurements highlighted that the appropriate functionalization of the silica particles leads to noticeable improvements of the barrier properties against water and ions permeation of the composite polymeric coating with respect to the unfilled UV curable resin.

Synthesis of 1-propenyl ethers and their using as modifiers of UV-cured coatings in radical and cationic polymerization

The 1-propenyl ethers of diols and polyols have recently attracted increasing attention as monomers and comonomers because these compounds undergo UV -photoinitiated polymerization. The synthesis of 1-propenyl ethers via the isomerization of corresponding, readily available allyl ethers catalysed by homogenized transition metal complexes with recycling of catalyst has been described. The properties of UV-cured coatings have been investigated for various compositions containing: the model ether (i.e. 1,4-di(1-propenyloxy)-butane), the unsaturated polyester resin [Estromal 103] or epoxy resin [Epidian 6] and radical (i.e. Irgacure 184) or cationic (i.e. triarylsulfonium salts with metal halide anions: PF 6 −, SbF 6 −) initiators. The purified or unrefined (i.e. including 0.05 mol% homogenized ruthenium(II) complex [RuClH(CO)(PPh 3) 3]) 1,4-di(1-propenyloxy)butane were applied as modifiers. The effect of presence of homogenized [RuClH(CO)(PPh 3) 3] in the composition has been discussed.

Determination of key variables affecting surface properties of UV curable coatings using experimental design

The influence of prepolymer (urethane acrylate or polyesteracrylate) type, triacrylate (trimethyolpropane triactylate or ethoxylated trimethylolpropane triacrylate) type and the concentration of silicone acrylate on the surface properties of UV cured films was studied. The effect of these variables on the pencil hardness and gloss was determined by using a full factorial experimental design. The results showed that the prepolymer type and the concentration of silicone acrylate were the most significant factors affecting surface hardness and gloss of UV cured films, respectively. Specifically, the coating formulation with polyester prepolymer resulted in improved surface hardness of the UV cured film, while increasing the concentration of the silicone acrylate significantly decreased the gloss. In addition, the predictive mathematical models obtained through analysis of variance provide a reasonable approximation of actual experimental measurements.

Properties of UV-curable coatings containing fluorinated acrylic structures

UV-curable systems based on the copolymerisation of typical acrylic resins with fluorinated derivatives were prepared and their properties investigated. Firstly we used as comonomer, 4,4′-hexafluoroisopropylidendiphenoldihydroxyethyletherdiacrylate which gives rise to homogeneous systems when mixed with the corresponding hydrogenated monomer. By using perfluoropolyetherurethanemethacrylates, films having interesting properties were obtained. When copolymerising a low amount of fluorinated acrylates with acrylic resins, the bulk properties of the films remained unchanged, but a selective modification of the surface was obtained. A series of acrylic esters of alcohols having a perfluorinated group −C n F 2 n+1 were investigated. In all cases, a selective enrichment of the fluorinated monomer on the film surface was observed, depending on the monomer structure, its concentration and the type of substrate.

Investigation of the effects of formulation on selected properties of UV curable IPN coatings

Ultraviolet curable coatings based on urethaneacrylic resins were prepared by free radical polymerization. The effects of photoinitiators on the curing reaction and the influence of polyol types and dimethylopropionic acid (DMPA) amounts on the properties of UV curable coatings prepared by free radical polymerization (UVF) were investigated. The effects of polymerization (UVC) and the consequences of postcuring conditions on the properties of UVC were evaluated. The interpenetrating polymer network (IPN) containing UV curable coatings (UVIPN), which were composed of UVF and UVC at different ratios (by weight), were prepared. The properties of UVIPN with varied UVF/UVC ratios were studied.

The effects of cure temperature on the thermomechanical properties of UV curable coatings

AbstractA method is presented to study the mechanical behavior of soft, UV curable coating material as a function of temperature of the prepolymer at cure. For such materials, the crosslink density (hence, equilibrium modulus) is found to decrease with increasing cure temperature. The three primary coatings are: a polyurethane acrylate with a nominal equilibrium tensile modulus of 200 psi, a polyurethane acrylate with a nominal equilibrium modulus of 1200 psi, and a non‐urethane acrylate with a nominal equilibrium tensile modulus of 60 psi.