2,2′-二邻甲氧基苯基-4,4′,5,5′-四苯基-1,2′-二咪唑复合光引发体系的光聚合动力学研究

本文研究了对2,2′-二邻甲氧基苯基-4,4′,5,5′-四苯基-1,2′-二咪唑(BMOIM)复合光引发体系引发聚合动力学过程.采用紫外光谱仪对引发剂、供氢体、增感剂在紫外区的吸收谱图进行了表征.利用实时红外光谱仪对复合光引发体系引发聚合动力学过程进行实时监测,考察了不同光强、引发剂浓度以及不同官能度单体对反应速率及最终双键转化率的影响.结果表明,在引发剂浓度为0.6%(质量分数)时,20s内双键转换率达到96%,随着引发剂浓度的提高,聚合速率增大.聚合速率以及最终双键转化率随着光强增大而增大;双官能团单体的最终双键转化率比三官能团单体的最终双键转化率要高.     

含氟光引发剂的合成及其性能研究

以2-羟基-4'-(2-羟乙氧基)-2-甲基苯丙酮(Irgacure 2959)和全氟辛酰氯(PFOC)为原料合成了光引发剂全氟辛酸-2-[4-(2-羟基-2-甲基丙酰)苯氧基]乙酯(2959-F),利用红外光谱(FT-IR)和核磁共振(¹⁹F NMR)对2959-F进行了结构表征;通过紫外吸收光谱测定了2959-F的紫外吸收谱;通过实时红外光谱(RT-IR)对合成的含氟光引发剂进行了光聚合反应动力学研究,考察了光强和引发剂浓度对单体的双键转化率和聚合速率影响,并研究了光引发剂2959-F的抗氧阻聚性能.结果表明:随着光强的增大,单体的双键转化率和聚合速率增加;在一定范围内,引发剂的浓度越高,双键转化率越高,聚合速率越快.2959-F具有较高的双键转化率和较快的聚合速率,并且具有较好的抗氧阻聚性.     

Investigation of termination reactions in free radical photopolymerization of UV powder formulations

The termination mechanisms occurring in a UV powder coating system during photopolymerization process are investigated and compared to a conventional acrylate monomer system. The influence of the photoinitiator concentration, viscosity and conversion percentage of the monomer are assessed leading to the study of curing kinetics of a UV powder urethane diacrylate based system. It is shown that termination occurs mainly by bimolecular termination (PRT). This mechanism is related to low reactive double bonds concentration and high photoinitiator concentration in the UV powder system. Moreover, the effect of surrounding atmosphere points out the role of the oxygen on polymerization mechanisms.     

Kinetic study of light-induced polymerization by real-time UV and IR spectroscopy

Real time ultraviolet (RTUV) spectroscopy was used to study the photolysis kinetics of a radical-type morpholino initiator, during the polymerization of a multiacrylate monomer exposed to UV radiation in bulk, in solution, in a polyurethane-acrylate resin, and in a poly(methyl methacrylate) matrix. The photolysis rate constant k was determined from the exponential loss profile recorded; it was found to vary between 0.1 and 3s^?1, depending on the light intensity and on the monomer concentration. The quenching of the photoinitiator excited states by the acrylate monomer was shown to be an important deactivation pathway which substantially reduces the rate of initiation. The observed influence of the film thickness and photoinitiator concentration on the k value were accounted for by the internal filter effect. Conversion versus time curves were recorded by real time infrared (RTIR) spectroscopy for the various systems examined, thus allowing a direct comparison of both the actual polymerization rate and the residual unsaturation content of the cured polymer. Various factors were shown to be responsible for the early stop of the polymerization, such as depletion of the photoinitiator, O₂ inhibition, or vitrification of the polymer. The photoinitiated cationic ring-opening polymerization of a cycloaliphatic diepoxy monomer was also studied in real time by RTUV and RTIR spectroscopy. Despite a very fast photolysis of the triarylsulphonium initiator, the polymerization of the epoxy monomer developed less rapidly than for the acrylic monomer, with shorter kinetic chain lengths. A linear relationship was found to exist between the decay rate constant and the light intensity, for both the radical and the cationic photoinitiators, as expected for a direct photolysis process.     

2,2′,5-三(2-氟苯基)-4-(3,4-二甲氧基苯基)-4′,5′-二苯基-1,1′-二咪唑复合引发体系光聚合动力学性能研究

利用实时红外对由光引发剂2,2′,5-三(2-氟苯基)-4-(3,4-二甲氧基苯基)-4′,5′-二苯基-1,1′-二咪唑(WJ-HABI)、增感剂4,4—二(N,N′—二甲基氨基)苯甲酮(EMK)及供氢体N-苯基甘氨酸(NPG)组成的复合引发体系进行光聚合动力学研究.探讨了复合引发体系的浓度、不同配比、紫外光的强度及...     

Substituted Benzophenones as Photoinitiators

Substituted benzophenone photoinitiators were synthesized and characterized by spectroscopy methods. Their absorption spectra and kinetics of the polymerization were compared to benzophenone itself. The kinetics of the photopolymerization of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate (TMPTA) was studied by measuring the polymerization heat evolution of sample, irradiated with a laser. The influence of photoinitiator concentration and light intensity on the polymerization was also studied.     

2-(4-甲氧基苯基)-4,6-双(三氯甲基)-S-三嗪光引发剂的合成及其光聚合动力学性能研究

以对甲氧基苯甲腈和三氯乙腈为原料合成了光引发剂2-(4-甲氧基苯基)-4,6-双(三氯甲基)-S-三嗪(MBTT),通过傅里叶红外光谱仪、核磁共振仪和紫外吸收光谱对所合成的产物结构进行了表征.并利用实时红外(RT-IR)对该引发剂进行了光聚合反应动力学研究,考察了单体、引发剂浓度和光强对引发速率及单体转化率的影响.结果表明,MBTT是一种高效的紫外光引发剂,在引发剂用量为0.1%时光聚合的单体转化率就能达到90%;随着光强的增大,单体的双键转化率和最大反应速率都增大,诱导期缩短;双丙烯酸酯类单体的双键转化率比三丙烯酸酯类单体的双键转化率要高.     

Kinetic investigations on the UV-induced photopolymerization of a diacrylate by time-resolved FTIR spectroscopy: the influence of photoinitiator concentration, light intensity and temperature

Time-resolved FTIR-ATR spectroscopy was used to study the kinetics of the photopolymerization of a diacrylate using a morpholino ketone as photoinitiator. The curing reaction was induced by monochromatic UV radiation with a wavelength of 313 nm. The influence of photoinitiator concentration [PI], light intensity I₀, and temperature on the polymerization rate R_p and the double bond conversion was investigated. The dependence of R_p on [PI] and I₀, respectively, was found to fit with theoretical predictions very well. In contrast, an increase of the temperature was found to have no effect on R_p.     

Synthesis and photopolymerization kinetics of benzophenone piperazine one‐component initiator

A one‐component type II photoinitiator (PDBP), based on 4‐hydroxybenzophenone (HBP), acryloyl chloride, and piperazine, was synthesized and its structure was confirmed by ¹H‐NMR. The photopolymerization kinetics of the photoinitiator was studied by real‐time Infrared spectroscopy (FT‐IR). It indicated that PDBP was a more effective photoinitiator than that of BP/triethylamine (TEA). The rate of polymerization, final conversion increased and the induction period shortened with increase in PDBP concentration, light intensity, and amine concentration. The kinetics of photopolymerization for TPGDA incorporating PDBP in the presence of different tertiary amines as the initiating system indicated that the PDBP/TEA combination exhibited the highest polymerization rates among the PDBP/amine combinations. Copyright © 2007 John Wiley & Sons, Ltd.     

Accompanying of parameters of color,gloss and hardness on polymeric films coated with pigmented inks cured by different radiation doses of ultraviolet light

In the search for alternatives to traditional paint systems solvent-based, the curing process of polymer coatings by ultraviolet light (UV) has been widely studied and discussed, especially because of their high content of solids and null emission of VOC. In UV-curing technology, organic solvents are replaced by reactive diluents, such as monomers. This paper aims to investigate variations on color, gloss and hardness of print inks cured by different UV radiation doses. The ratio pigment/clear coating was kept constant. The clear coating presented higher average values for König hardness than pigmented ones, indicating that UV-light absorption has been reduced by the presence of pigments. Besides, they have indicated a slight variation in function of cure degree for the studied radiation doses range. The gloss loss related to UV light exposition allows inferring that some degradation occurred at the surface of print ink films.     

UV-光固化光纤涂料的研制

本文采用环氧丙烯酸酯与聚氨酯丙烯酸酯共混聚合的方法制备出新型的UV-光固化光纤涂料,其主要性能较好.研究了基体组成、引发剂、稀释剂以及固化工艺对UV-固化光纤涂料的光固化速度的影响.通过实验发现,环氧丙烯酸酯与聚氨酯丙烯酸酯的配比为 4:6～6:4、稀释剂的含量不大于20%时固化速度较快、性能较好,同时固化时灯距与固化膜厚度对固化速度的影响较大.     

Monitoring photopolymerization of trimethylolpropane triacrylate using a quartz crystal resonator

The UV photopolymerization of trimethylolpropane triacrylate with a photoinitiator of 2‐ethylanthraquinone is monitored using the variation of resonant resistance of a quartz crystal resonator to investigate the polymerization kinetics. The roles of initiator concentration and irradiation time are experimentally examined, and it is found that two different kinetics are involved in the photopolymerization. The initiator radicals produced by the UV light proceed the polymerization as long as the monomer remains even after the UV illumination has stopped. The experimental results indicate that the photopolymerization has the first‐order kinetics at the first‐ and the zeroth‐order kinetics followed. With the high concentration of initiator the polymerization occurs in the first‐order kinetics only, and so does with long irradiation time. The polymerization constants of the first and zeroth‐order kinetics are estimated from monitoring monomer amounts at different polymerization conditions. The photopolymerization is characterized with the FTIR spectroscopy. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Preparation and characterization of a water soluble methylated β‐cyclodextrin/camphorquinone complex

A water soluble methylated β‐cyclodextrin/camphorquinone (MCD/CQ) complex, based on methylated β‐cyclodextrin (MCD) and camphorquinone (CQ), was prepared and its structure was characterized by FTIR, ¹H‐NMR, and UV–vis spectra. The photopolymerization kinetics of MCD/CQ in the water soluble monomer system was studied by Real‐time Infrared spectroscopy (RT‐IR). Compared to the photopolymerization carried out under nearly identical conditions but without MCD, the polymerization rate and final conversion initiated by a CQ‐triethanolamine photoinitiator system were slightly lower. The effects of different MCD/CQ concentration, triethanolamine concentration, and light intensity were also studied. Copyright © 2009 John Wiley & Sons, Ltd.     

Photoinitiated polymerization of acrylate,methacrylate, and vinyl ether end‐functional polyisobutylene macromonomers

Polyisobutylene‐based UV cured networks potentially useful as sealants were synthesized by photopolymerization of well‐defined polyisobutylene methacrylate (PIB‐MA), acrylate (PIB‐A) and vinyl ether (PIB‐VE) di‐ and trifunctional macromonomers. The kinetics of photocrosslinking were measured using an optical pyrometer apparatus and optimized with respect to different experimental parameters. PIB‐MA/A macromonomers displayed enhanced reactivity in radical photopolymerization in the presence of a bis(acylphosphine) oxide photoinitator. PIB‐VE macromonomers exhibited a high rates of photopolymerization with (4‐n‐octyloxyphenyl)phenyliodonium hexafluroantimonate as the photoinitiator. The rates as well as the ultimate monomer conversions were increased by increasing the irradiation light intensity. The inherent induction period associated with oxygen inhibition in the photopolymerization of PIB‐MA was significantly reduced by optimizing the choice of photoinitiator. A detailed investigation of the concentration of MA/A/VE end groups revealed the presence of a prominent saturation effect in the photopolymerization of PIB‐A, which was absent with PIB‐MA and PIB‐VE. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

可聚合型光引发剂4-丙烯酰氧基二苯甲酮的光聚合性能研究

以实时红外光谱(RT-IR)法研究了合成的4-丙烯酰氧基二苯甲酮(4-ABP)的光聚合动力学性质,考察了不同单体、不同引发剂和助引发剂浓度、不同光强对聚合性能的影响.以萃取法对比研究了4-ABP和二苯甲酮(BP)在固化膜中的的残留量.结果表明,4-ABP是一种非常有效的光引发剂.随着引发剂浓度和光强的增大,单体转化率、最大反应速率都增大,诱导期缩短.萃取实验表明4-ABP在固化膜中的残留量远低于BP.     

Photocrosslinking of polyethylene. I. Photoinitiators,crosslinking agent,and reaction kinetics

High density polyethylene has been photocrosslinked in the melt by using 4-chlorobenzophenone (4-CBP) as photoinitiator and triallylcyanurate (TAC) as crosslinking agent. Various factors affecting the crosslinking process (photoinitiator used and its concentration, irradiation temperature and time, atmosphere, UV light source, light intensity) were examined. By optimizing the irradiation conditions, it was found that samples up to 2 mm thick could readily be crosslinked to high gel content (≈ 90%) with satisfactory homogeneity within very short irradiation times (≈ 15 s). The kinetic analysis of the crosslinking process showed a linear relation between log S and log t (S is the sol fraction t is the irradiation time). An induction period was observed, the length of which decreased with increasing concentration of 4-CBP and increasing light intensity. An upper limit of gel content was also found for long irradiation times at a level depending on the concentration of 4-CBP. The crosslinking rate was proportional to the second order of light intensity at lower intensity and changed to first order at higher light intensity. A mechanism based on the recombination of chain radicals through both allyl and alkyl type radicals of TAC was proposed.     

可聚合二苯甲酮类光引发剂的合成及其光聚合性能研究

以4-(2,3-环氧丙氧基)二苯甲酮(EBP)和丙烯酸为原料,通过开环反应合成了含有不饱和双键的可聚合光引发剂4-(丙烯酸-2-羟基丙酯-3-氧基)二苯甲酮(AEBP).采用红外光谱(FT-IR)、核磁共振氢谱(¹HNMR)对其结构进行表征,利用紫外吸收光谱对AEBP的紫外吸收波长进行表征,通过实时红外(RT-IR)研究了AEBP引发丙烯酸酯单体的光聚合动力学.采用萃取法对比了BP与AEBP引发固化体系后的迁移性.结果表明,随AEBP浓度增加,单体最终转化率增加;当助引发剂N,N-二甲氨基苯甲酸-乙酯(EDAB)浓度为1.2%时,单体最终双键转化率最高;AEBP对双官能度单体的引发效率较之三官能度单体的好;聚合速率随光照强度的增强而变快;固化后AEBP的迁移性比传统的BP大大降低.     

Photoinitiation rate profiles during polymerization of a dimethacrylate-based resin photoinitiated with camphorquinone/amine. Influence of initiator photobleaching rate

The photodecomposition of camphorquinone (CQ)/amine during the photo polymerization of a dimethacrylate-based resin under continuous irradiation was investigated in thick samples. The global CQ photoconsumption was measured by monitoring the decrease in light absorption as a function of irradiation time and the kinetics were satisfactory fitted to a first order expression where the rate constant of photobleaching was proportional to the irradiation intensity. In a thick sample, the photobleaching of the photoinitiator is accompanied by a deeper penetration of the light through the underlying layers. These gradients of photoinitiator concentration, light intensity and photoinitiation rate along the path of irradiation were calculated. The photodecomposition reaction was spatially inhomogeneous and the degree of nonuniformity increased with increased initial sample absorbance. The influence of the photobleaching process on the polymerization reaction was examined. The photobleaching rate of CQ was much slower than the polymerization rate and only 20% of the initial amount of CQ was consumed before the polymerization reaction had almost ceased. Results obtained in this research highlight the inherent interlinking of light attenuation and photobleaching rate in bulk polymerizing systems.     

基于α-羟烷基苯酮(HAPK)可聚合大分子光引发剂的合成及其引发三丙二醇双丙烯酸酯(TPGDA)光聚合动力学的研究

以α-羟烷基苯酮(HAPK)、甲苯-2,4-二异氰酸酯(TDI)、聚乙二醇600(PEG600)和丙烯酸-β-羟乙酯(HEA)为原料,通过3步反应,合成了一种可聚合大分子光引发剂:HAPK-TDI-PEG600-TDI-HEA(HTPTH).用IR对反应过程进行了监测.通过Photo-DSC研究了HTPTH引发三丙二醇双丙烯酸酯(TPG-DA)光聚合动力学,考察了光强、引发剂浓度对TPGDA光聚合动力学的影响.结果表明,随着引发剂浓度和光强的增大,最大反应速率对应的转化率、单体最终转化率、最大反应速率都增大,达到最大反应速率所需的时间减小.     

Characterization of UV-cured polyester acrylate films containing acrylate functional polydimethylsiloxane

Acrylate functional polydimethylsiloxane (AF-PDMS) was tested as a reactive additive in UV-curable coating formulations. Pencil hardness, solvent resistance, and gloss of the UV-cured films were measured to study the influence of AF-PDMS content on coating properties. Depth-profile analysis by FTIR-ATR and Raman spectroscopy was also performed to investigate the effect of AF-PDMS on the behavior of film formation during UV curing. The kinetics of photopolymerization were monitored by photo differential scanning calorimetry (photo-DSC). Our results show that AF-PDMS containing coating formulations are very sensitive to oxygen inhibition, so that an inert environment such as nitrogen purging is required to avoid coating defects.