Effects of small molecular weight silicon‐containing acrylate on kinetics,morphologies, and properties of free‐radical/cationic hybrid UV‐cured coatings

A series of UV‐curable, silicon‐containing mixtures were prepared by adding different micro amounts of small molecular weight silicon‐containing acrylate KH570 to an interpenetrating polymer network system composed of cycloaliphatic polyurethane acrylate, trimethylolpropane triacrylate, cycloaliphatic epoxy resin, free‐radical photoinitiator Irgacure 754 and cationic photoinitiator Irgacure 250 with a weight ratio of 15 : 15 : 65 : 1 : 4. Hybrid coatings with different addition amounts of KH570 (0.2, 0.6, 1.0 wt %) were cured from the mixtures by UV‐initiated free‐radical/cationic dual curing technique. Final reactant conversions and photopolymerization rates of the hybrid UV‐cured coatings were improved with the increase of KH570 content, as evaluated by conversion profiles. The morphologies and microstructures were characterized by scanning electron micro‐scopic, atomic force micrographic, and fourier transform infrared spectrophotometer measurements. Thermal, mechanical, and surface properties of the hybrid UV‐cured coatings were investigated. The increase in KH570 content caused a decrease in mechanical properties besides the breaking elongation. Thermo‐gravimetric analysis revealed that the incorporation of silicon into cross‐linked network structure resulted in high thermal stability. The surface properties of hybrid UV‐cured coatings, such as hardness, contact angle, flexibility, and glossiness were also examined. It is found that transparent hybrid coating with the addition of 1.0 wt % KH570 exhibited a relatively higher contact angle as a direct result of a relatively higher hydrophobic surface. These researches showed that micro amounts of small molecular weight silicon‐containing acrylate could greatly influence the morphologies of liquid nitrogen quenching cross sections and properties of hybrid UV‐cured coatings and could be used to modify UV‐cured coatings for some superior properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40655.     

Preliminary study on the utilization of lignin as filler in ultra‐violet (UV) curable system

In this study, Alcell lignin was used as filler in aliphatic urethane acrylate ultra violet (UV) curable resin system. The coating system was UV cured in the presence of free radical photoinitiator and cationic photoinitiator. The results showed that those with free radical photoinitiator produced coating film with higher degree of curing than those with cationic photoinitiator. The result of iodine number determination also showed that the unsaturated groups present in the UV curable system had reduced. This indicated that radical polymerization had taken place in the curing process of UV curable resin incorporated with lignin. In addition, the lignin content did not influence the curing process of the coating film. As for the coating film, it showed that the mechanical properties of the film were significantly influenced by the lignin content. This phenomenon was contributed by inherent stiffness of the lignin. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

紫外光引发聚(丙烯酸-丙烯酰胺)/膨润土高吸水性复合材料的制备研究

以N,N-亚甲基双丙烯酰胺(MBAM)为交联剂,Irgacure184为光引发剂,采用紫外光引发聚合的方法制备了聚(丙烯酸-丙烯酰胺)/膨润土高吸水性复合材料。研究了膨润土用量、光引发剂、交联剂、中和度等因素对吸水性能的影响,并用红外吸收光谱(FTIR)、X射线衍射(XRD)和扫描电镜(SEM)的方法表征了复合材料的结构和形态。     

Morphology and thermal and dielectric behavior of cycloaliphatic epoxy/trimethacrylate interpenetrating polymer networks for vacuum‐pressure‐impregnation electrical insulation

Vacuum pressure impregnation has been known as the most advanced impregnation technology that has ever been developed for large and medium high‐voltage electric machines and apparatuses. We developed one new type of vacuum‐pressure‐impregnation resin with excellent properties by means of a novel approach based on in situ sequential interpenetrating polymer networks resulting from the curing of trimethacrylate monomer [trimethylol‐1,1,1‐propane trimethacrylate (TMPTMA)] and cycloaliphatic epoxy resin (CER). In this study, the influence of the concentrations of the components and their microstructures on their thermal and dielectric behaviors were investigated for the cured CER/TMPTMA systems via atomic force microscopy, dynamic mechanical analysis, thermogravimetric analysis, and dielectric analysis. The investigation results show that the addition of TMPTMA to the CER–anhydride system resulted in the formation of a uniform and compact microstructure in the cured epoxy system. This led the cured CER/TMPTMA systems to show much higher moduli in comparison with the pure CER–anhydride system. The thermogravimetric analysis results show that there existed a decreasing tendency in the maximum thermal decomposition rates of the cured CER/TMPTMA systems, which implies that the thermal stability properties improved to some extent. The dielectric analysis results show that the cured CER/TMPTMA systems displayed quite different dielectric behaviors in the wide frequency range 0.01 Hz–1 MHz and in the wide temperature range 27–250°C compared with the cured CER–anhydride system. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Ultraviolet‐curable epoxidized sunflower oil/organoclay nanocomposite coatings

Hybrid nanocomposite coating films, prepared by the incorporation of epoxidized sunflower oil into organoclay, can be cured by ultraviolet radiation with either cationic or hybrid initiation. The organoclay used in this study was prepared by a cationic exchange process in which sodium ions were replaced by alkyl ammonium ions. The effects of types of photoinitiators on energy consumption in the curing process were studied. Formulations with a hybrid photoinitiator required less energy in the curing process than those with a cationic photoinitiator. Moreover, the physical properties of dried films were examined as a function of the organoclay incorporation, and it was found that the hardness of the films increased as the amount of organoclay in the formulation increased. The X‐ray diffraction patterns of an ultraviolet‐curable organoclay‐incorporated film showed an exfoliated structure of the organoclay in the ultraviolet‐curable coating film. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Acrylic resins resisting oxygen inhibition during free‐radical photocuring. I. Formulation attributes

A resin system was found to be resistant to the formation of an oxygen‐inhibited layer when cured in air via conventional free‐radical photopolymerization. The resins, containing multifunctional acrylates and a high concentration of a photoinitiator, were applied as thin film coatings and photocured with either visible light (400–500 nm) or UV light (254 nm). Fourier transform infrared spectroscopy with an attenuated total reflection attachment and pencil hardness were used to assess the surface double‐bond conversion and the surface hardness of the coatings cured in air and without air, respectively. The surfaces of many tested resins could produce similar conversions under both curing conditions. Optimally formulated resins had a high conversion and hardness even when the irradiance was as low as 50 mW/cm² for the visible light and 4 mW/cm² for the UV light. The requirements for possessing such a unique curing property are presented. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Photopolymerizable hyperbranched (meth)acrylated poly(amine ester)

A hyperbranched (meth)acrylated poly(amine ester) (HPAE‐2‐A) was synthesized by the modification of the hydroxyl end groups of the second generation of a hyperbranched poly(amine ester) with acryloyl chloride and methacrylic anhydride. The photopolymerization kinetics were investigated with photo‐differential scanning calorimetry and Fourier transform infrared. The properties of HPAE‐2‐A, including the dynamic viscosity, pendulum hardness, and shrinkage, were also studied in comparison with those of a hyperbranched methacrylated poly(amine ester) (HPAE‐2‐MA) prepared in the laboratory and traditional epoxy acrylate and epoxy methacrylate. HPAE‐2‐A polymerized rapidly under UV irradiation in the presence of a photoinitiator and had a higher final conversion of double bonds. The thermomechanical properties of UV‐cured HPAE‐2‐MA films were compared with those of EB‐cured films measured with a dynamic mechanical thermal analyzer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 168–173, 2003     

Curing of crust leather by ultraviolet radiation with urethane acrylate: Role of pigment

Eight different formulations were developed with four diacrylate reactive monomers such as tripropylene glycol diacrylate (TPGDA), 1,4‐butanediol diacrylate (BDDA), 1,6‐hexanediol diacrylate (HDDA), and 2‐ethylene glycol dimethacrylate (EGDMA) and aromatic urethane diacrylate (M1100) in order to modify the crust leather surface. To study the effect of pigment on the performance of ultraviolet (UV)‐cured leather surface, 1% pigment (congored) was incorporated in the formulations. Irgacure 369 (2%) was also used in the formulation as photoinitiator. The gel content, tensile strength, elongation at break, and pendulum hardness of UV‐cured thin films with and without pigment was studied. The films without pigment produced better properties. Among all the diluents, BDDA‐containing films showed the best performance. Different properties of UV‐coated leather surface such as pendulum hardness, tensile strength, elongation, gloss (at 20° and 60°), adhesion, and abrasion were studied. Effect of gloss on simulating weathering was also performed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 692–697, 2002     

On-line monitoring of cycloaliphatic epoxy/acrylate interpenetrating polymer networks formation and characterization of their mechanical properties

The novel interpenetrating polymer networks (IPNs) based on cycloaliphatic epoxy resin (CER) containing cyclohexene oxide groups and tri-functional acrylate, trimethylol-1, 1, 1-propane trimethacrylate (TMPTMA) were synthesized. The formation of the IPNs was on-line monitored by means of polarizing optical microscope, time-resolved light scattering and Fourier transform infrared spectroscopy. The morphological and mechanical properties of the resultant IPNs were investigated and evaluated with scanning electron microscopy (SEM) and dynamical thermal mechanical analysis (DTMA), respectively. The on-line monitoring results showed that during the course of the IPNs formation, the TMPTMA component was cured more quickly than the CER component, leading to the formation of the sequential IPNs. During the early curing stage, there were the phase separation phenomena in the CER/TMPTMA system. The SEM results revealed that although there were some slight phase separation phenomena in the CER/TMPTMA system in the early curing stage, the resultant IPNs displayed the homogeneous structures and did not show the apparent phase separation morphology. The DTMA results revealed that the resulting IPNs exhibited rather higher modulus and denser cross-linking network structure than the neat CER system.     

Thin film solvent‐free photopolymerization of n‐butyl acrylate. I. Static film studies

The results are presented for a detailed investigation involving the free‐radical photopolymerization of n‐butyl acrylate in the form of thin static films. The aim of this work is to benchmark the performance of a novel thin film spinning disk reactor that may be used for the continuous production of linear polymers using photoinitiation. Industrially relevant film thicknesses (200 μm to 1 mm) are studied as opposed to earlier work that looked into extremely thin films (5–25 μm). Such extreme film thicknesses will be difficult to sustain in a thin film reactor without adversely affecting the wettability of the reaction surface and the uniformity of the film. The effects of four main variables (film thickness, UV intensity, initiator concentration, and exposure time) are studied under static film conditions. A 366‐nm wavelength is utilized for the UV radiation with 2,2‐dimethoxy‐2‐phenylacetophenone (Irgacure 651) as the photoinitiator dissolved in n‐butyl acrylate. The molecular weights, polydispersities, and monomer conversions are measured by gel permeation chromatography. In a 400 μm thick film, conversions of >90% can be achieved with an exposure time of 40 s at a radiation intensity of 175 mW/cm². The results using the same polymerization system in the spinning disk reactor are presented and compared with the static film results in Part II of this series. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2079–2095, 2004     

Photoinitiability of a water-borne polysiloxane-modified benzophenone macromolecular photoinitiator

This paper reported a water-borne polysiloxane-modified benzophenone macromolecular photoinitiator (WPSHBP), whose characteristics of the photopolymerization, the migration of photolysis fragments, the volatility, and reduction of oxygen inhibition were discussed in detail. WPSHBP has a maximum absorption peak at 286 nm, and the molar extinction coefficient (ε_286 nm) is 23200 M^?1 cm^?1. The photopolymerization rate and final double bond conversion of the system initiated by WPSHBP were enhanced with the increasing contents of triethanolamine (TEOA) and WPSHBP and irradiation intensity. WPSHBP exhibits a low migration of photolysis fragments and volatility compared with small-molecular photoinitiator benzophenone (BP). The cured films initiated by WPSHBP have good mechanical properties and thermostability compared with that by 2-hydroxy-4’-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959). More importantly, the water-borne polysiloxane-modified photoinitiator can mitigate the oxygen inhibition in radical photopolymerization due to its enrichment on the surface of the photopolymerization system.     

丙烯酸酯/环氧的自由基/阳离子同步光聚合混合体系的研究

科学技术的进步,对新材料的要求逐步向着多功能和高性能的方向发展,单组分材料已难于满足这种要求,在高分子材料方面,人们采用了共混、接枝、嵌段等方法以达到改善和提高性能的目的。感光性高分子是一类很重要的功能材料,至今,大部分采用自由基聚合方式制备。近年来,阳离子引发体系发展很快,特别鎓盐光引发体系受到很大的重视,发展迅速。目前自由基聚合及阳离子聚合已经成为合成感光性高分子材料的二种最     

Mechanical properties study of photocured paperboard surface treated with aliphatic epoxy diacrylate

In order to improve the quality of paperboard (a well‐known packing material) surface by photocuring method, different formulations were developed with aliphatic epoxy diacrylate (EA‐1020) oligomer along with reactive monomers of various functionalities. The reactive monomers are tripropylene glycol diacrylate (TPGDA), a difunctional monomer, and trimethylol propane triacrylate (TMPTA), a trifunctional monomer. 2‐Benzyl‐2‐dimethylamino‐1(4morpholinophenyl) butanone‐1 (Irgacure 369), a photoinitiator (2%), was incorporated into the formulations to initiate photocuring reaction. The formulated solutions were coated on clean glass plate and irradiated under UV radiation of different intensities. Different physical properties like pendulum hardness and gel content of the cured films were studied. The formulation containing TMPTA showed better properties. After characterization of the films, these formulations were applied on paperboard surfaces and cured under the same UV radiation. Various physicomechanical properties such as pendulum hardness, tensile properties, surface gloss, adhesion, abrasion, and water uptake were studied. The best performance was obtained at 12 passes of radiation with 18% TMPTA‐containing formulation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1774–1780, 2003     

Photopolymerization kinetics of cycloaliphatic epoxide–acrylate hybrid monomer

An epoxide–acrylate hybrid monomer was synthesized by the controlled reaction of a cycloaliphatic epoxide and acrylic acid. The photopolymerization kinetics was investigated using a real‐time infrared spectroscopy technique. The influences of photoinitiator concentration, free radical initiator and polymerization atmosphere on the polymerization were studied. The hybrid monomer showed unique photopolymerization kinetics in the photopolymerization process and the final conversions of epoxy groups and acrylate double bonds were improved synchronously. Dynamic mechanical analysis results demonstrated that the hybrid monomer cured film formed a more uniform polymer network than the blend of epoxy acrylate and epoxide. Copyright © 2007 Society of Chemical Industry     

Ultraviolet‐curing behavior and mechanical properties of a polyester acrylate resin

Ultraviolet (UV) curing technology has been widely used in many applications because it has several distinct advantages compared to solvent‐based processes or thermal‐curing technology. The effects of photoinitiator types and their contents as well as reactive diluent types and their contents on the UV‐curing behavior and mechanical properties of a UV‐curable polyester acrylate resin were investigated in this study. Three photoinitiators, Irgacure 184, Darocur 1173, and benzophenone, were used in this study. Hexanediol diacrylate, tripropylene glycol diacrylate, and trimethylol propane triacrylate were used as reactive diluents to modify the properties of the acrylate resin. The change of chemical structure during UV curing was monitored by FTIR. A universal testing machine was used to measure the tensile properties of various UV‐cured acrylate films of different compositions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3921–3928, 2004     

Synthesis and characterization of palm‐based resin for UV coating

The production of UV curable acrylated polyol ester prepolymer from palm oil and its downstream products offer potential and promising materials for applications such as polymeric film preparation and coatings. In this study, palm olein polyol was reacted with acrylic acid in the presence of a catalyst and inhibitors via condensation esterification process. The reaction temperature of 80°C and the stirring rate of 400 rpm produce a homogeneous product. Based on iodine value result, the suitable amount of p‐toluene sulfonic acid monohydrate used as catalyst was 3.0% (w/w) of palm olein polyol. Different UV curable formulations have been investigated using the synthesized prepolymers with monomers and a small amount of photoinitiator. Monomers used were 1,6‐hexanediol diacrylate (HDDA) and trimethylolpropane triacrylate (TMPTA) while photoinitiator used was 1‐hydroxy cyclohexyl phenylketone (Irgacure 184). The mixtures were cured to make thin polymeric films under UV radiation with doses between 2 and 14 passes (energy per pass is 0.6 J/cm²). Coating and curing was carried out on glass for pendulum hardness and FTIR analysis. Pendulum hardness of the film prepared using monomer HDDA and the prepolymer previously synthesized using 3.0% catalyst was 24.5%. The radiation dose needed was 14 passes. The highest pendulum hardness of 49.4% was achieved using monomer TMPTA and the prepolymer synthesized using 2.0% catalyst. The radiation dose needed was 10 passes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

新型紫外线固化环氧树脂/丙烯酸酯改性水性聚氨酯的合成与性能

合成了一种新型的具有高交联密度和优异涂膜性能的环氧树脂和丙烯酸酯同时改性的紫外线（UV）固化水性聚氨酯（UV-EP-AC-WPUD）。通过环氧基团与以异氰酸酯基团（-N=C=O）封端的聚氨酯预聚体之间的反应引入质量分数为4%的环氧树脂E-20。同时,通过聚氨酯链的-N=C=O与二元丙烯酸酯（PEDA）以及季戊四醇三丙烯酸酯（PETA）的羟基之间的反应引入碳碳双键（C=C）,C=C的含量达到4.65 meq·g-1。 质量分数为3%的光引发剂Irgacure 2959被用于引发涂膜中C=C的聚合,涂膜的凝胶含量在12 s UV辐射之后达到91%,意味着C=C的聚合和交联速度快,同时所得到的涂膜的交联度非常高,不溶于溶剂丙酮,测试表明环氧树脂和两种丙烯酸酯单体已经成功嵌入聚氨酯链中,涂膜具有优异的力学性能和化学性能。     

Role of Photoinitiators in the UV Curing of Urethane Acrylate

Polymeric films were prepared under UV radiation with tetraacrylated urethane oligomer in combination with N-vinyl pyrrolidone (NVP) using a set of four photoinitiators (Irg 907, Irg 651, Irg 369, and Irg 184). The study evaluates optimum photoinitiator concentration and radiation dose. Various film properties such as gel content, swelling ratio in acetone, pendulum hardness, tensile strength, and elongation at break were determined. These formulated solutions were coated on wood substrates, and gloss and hardness of the film cured on the wood substrate were determined. Some of these properties are compared with those of the films cured on the glass plates. Irg 369 is found to be the best photoinitiator to produce better films, both on glass plate and on wood substrate.     

A novel ferrocenium salt as visible light photoinitiator for cationic and radical photopolymerization

A novel hybrid photoinitiator for visible light photopolymerization, (η⁶-3-benzoyl-4-chlorodiphenylamine) (η⁵-cyclopentadienyl) iron hexafluorophosphate (Fc-NBP), was synthesized and studied. Its absorption in the UV and visible light regions showed much stronger activity than those of either the commercialized cationic photoinitiator I-261 or the conventional free radical photoinitiator benzophenone, especially above wavelengths of 350 nm. When exposed to visible light, the photoinitiator under study initiates both cationic polymerization and radical polymerization. The photoinitiator's abilities in the photopolymerization of acrylates and epoxides were evaluated by near infrared (NIR) spectroscopy. The results from NIR clearly indicate that Fc-NBP exhibited high efficiency in photopolymerizing acrylate monomers. In the same lamp, however, benzophenone showed no photoinitiating ability. The photopolymerization rate of the diglycidyl ether of the bisphenol-A epoxy (DGEBA) oligomer was found to be slower than that of acrylates when using Fc-NBP as the photoinitiator. This study shows that the polymerization of epoxide DGEBA can be speeded up by adding a photosensitizer benzoyl peroxide (BPO), but BPO and tertiary amines do not affect the free radical photopolymerization of tripropylene glycol diacrylate (TPGDA). We conclude by providing a possible photoinitiation mechanism.     

聚氨酯-聚丙烯酸酯复合胶乳的制备及其性能研究

通过丙酮工艺法,分别制备了含有羧基作为内乳化剂的乙二胺扩链型水性聚氨酯(EDAWPU)和甲基丙烯酸β羟乙酯(HEMA)封端的水性聚氨酯(VLWPU)。为了改善水性聚氨酯(WPU)膜的性能,采用无皂乳液法制备了未交联型和交联型水性聚氨酯/聚丙烯酸酯复合乳液(UCPUA和CPUA)。通过红外对EDAWPU和VLWPU的化学结构进行了确认。使用TEM发现CPUA复合乳胶的形貌是以聚丙烯酸酯为核,聚氨酯为壳的核/壳结构。CPUA和UCPUA的分子量分别为310934和86522。从DSC曲线中能观察到CPUA膜的玻璃化转变温度相对较高。在CPUA膜中,通过交联CPUA的拉伸强度也得到增加。所以结果显示CPUA复合乳胶在硬度,附着力,柔韧性,光泽度和耐水性等方面均显示出了优异的性能。