UV-LED光固化体系光引发剂研究新进展

综述了可用于UV-LED光固化体系光引发剂的研究进展,包括传统光引发剂及其衍生物(硫杂蒽酮类、二苯甲酮类和酰基膦氧化物)、新型基团的光引发剂(咔唑基、萘酰亚胺基、吩嗪基、苯丙二茂基、咪唑基和三嗪基)以及高分子光引发剂。传统光引发剂的改性和大分子光引发剂的合成可以提高引发剂的稳定性。新型光引发剂的吸收波长与UV-LED光固化的发射波长匹配性较好,但该类光引发剂常需要加入助剂。此外,描述了氧阻聚对光固化体系的影响,指出了目前UV-LED光引发剂存在的不足,并展望了其发展应用前景。     

含硫杂蒽酮类光引发剂的聚合体系的光固化研究

首次Ｎ１２１型紫外光固化测试仪研究以硫杂蒽酮为光引发剂的光聚合体系的光固化性能。为测定以硫杂蒽桐为光引发剂的光聚合体系的光聚全速度提供了新的方法，同时讨论了光 发射波长与光引发剂的吸收波长的关系。     

央速成型光固化树脂用光引发剂的种类与应用

快速成型光固化技术是绿色环保的新型技术,主要是利用激光或者紫外光引发固化。然而光引发剂是快速成型光固化体系中重要的组成部分,对研究和发展光固化产品有着十分重要的影响,筛选高效的光引发剂已经成为当前研究的热点。本文主要介绍和分析了常用光引发剂的引发固化的原理,不同类型光引发剂的性能、结构与应用。     

快速成型光固化树脂用光引发剂的种类与应用

快速成型光固化技术是绿色环保的新型技术,主要是利用激光或者紫外光引发固化。然而光引发剂是快速成型光固化体系中重要的组成部分,对研究和发展光固化产品有着十分重要的影响,筛选高效的光引发剂已经成为当前研究的热点。本文主要介绍和分析了常用光引发剂的引发固化的原理,不同类型光引发剂的性能、结构与应用。     

紫外光固化涂料用光引发剂的应用研究进展

光引发剂作为紫外光固化体系中重要的组成部分,对产品的最终性能具有决定性作用。随着紫外光固化技术的快速发展,必须寻找与之相匹配、性能优异的新型光引发剂。针对现有光引发剂存在氧阻聚及价格方面的缺陷,科研人员开发出各种新型光引发剂。本文在总结传统的商业化光引发剂的分类、特点、合成方法的基础上,对其在紫外光固化体系中的光固化效率进行了讨论。     

一种新型UVA光敏型季铵盐类光产碱剂

针对光固化领域自由基聚合体系中存在的氧阻聚问题以及UV-LED灯作为光固化领域未来发展一趋势,本文以对UVA段紫外光敏感的硫杂蒽酮作为母核,合成了一种季铵盐类光产碱剂TX-Q-BPh_4。通过~1H NMR和ESI(±)-MS对该结构进行表征,UV-Vis,UV-DSC对其光敏性,光解性能以及光引发性能进行测试,结果表明该光产碱剂TX-Q-BPh_4在365/385/395 nm处的ε均达到10~3数量级,其光照后可光解产Lewis碱叔胺,可应用商业化的UV-LED灯,且该光产碱剂具有良好的抗氧阻聚性能。     

LED光源可激发光引发剂的研究进展

传统的光引发剂在光固化领域的应用主要是通过高压汞灯等光源来实现的，通过 UVB波段（ 280~320 nm）光子激发导致引发剂分子的裂解或者夺氢反应，产生自由基或阳离子等，引发相应的自由基或者阳离子聚合。但是，当 LED光源被发明之后，特别是 UVA波段和可见光波段的 LED光源，其特有的节能、环保等优势对于光固化行业的促进是有目共睹的。因此，传统光引发剂的吸收光谱和新 LED光源的发射光谱匹配性较差成为光固化领域被广泛关注的问题。一般来说，可以从 2个方向解决：一是 UVB波段的 LED光源的产业化；二是把光引发剂的吸收带红移到 UVA和可见光区。本文从光引发剂吸收带红移的角度论述了自由基型和阳离子型光引发剂的研究进展。     

α-羟基芳香酮类光引发剂的研究进展

传统的小分子光引发剂存在与活性稀释剂及树脂相容性差、迁移性大、气味以及光固化过程中的氧阻聚等问题。为了促进环境友好光固化技术的发展,结合光固化体系中的问题,从光引发剂的角度,综述了近年来国内外有关裂解型α-羟基芳香酮类光引发剂的发展。     

桐油基光引发剂的制备及性能

主要研究桐油基光引发剂的制备方式,并对桐油基光引发剂的性能做具体研究,希望通过此种改性光引发剂的制备,提升光固化技术、光引发剂的适用范围。     

聚氨酯丙烯酸酯光固化涂料配方性能研究

本论文研究了光引发剂和活性稀释剂在光固化配方中的作用和影响,当光引发剂含量较低时,光固化速率低,含量越高,固化速率越快,但增加到一定含量时,固化速率变化不明显;当使用光引发剂时应选择吸收波长与光源的发射波长相匹配的光引发剂,混合使用可以提高光固化速率;配方中使用单官能度活性稀释剂时会使涂膜硬度下降,而使用二官能度、三官能度活性稀释剂可以使涂层硬度增大,但其附着力反而下降。     

用FTIR跟踪监测环氧丙烯酸酯胶粘剂光固化过程的研究

用FTIR跟踪监测环氧丙烯酸酯胶粘剂光固化过程并研究了光引发剂体系中辐射时间与双键转化率的关系。研究结果显示,合理配合使用不同特征吸收波长的光引发剂,能有效利用紫外光源,提高固化速度。夺氢型光引发剂的引发活性低于断裂型光引发剂,断裂型光引发剂中α-羟基酮衍生物(1173)比α-胺基酮衍生物(907)和酰基膦氧化物(TPO)引发效率低。在α-羟基酮衍生物中185的引发活性又远远高于1173与184。复合型光引发体系和光引发剂与助引发剂联用的引发效率明显高于单一引发剂体系。     

阳离子光引发剂研究进展

阳离子型光引发剂是一类新型的紫外光固化材料的引发剂。本文介绍了阳离子光引发剂的主要种类及各自的特点 ,讨论了其光引发机理 ,并简述了阳离子光引发剂的的发展概况和主要用途。     

常用光引发剂在紫外光固化涂料中的应用研究

针对紫外光固化体系,研究了常用光引发剂在紫外光固化涂料中的应用。讨论了常用光引发剂的用量及其对亮光体系、亚光体系和色漆体系固化性能的影响。得出在紫外光固化涂料中选择引发剂的规律。     

Kinetic studies of a UV-curable powder coating using photo-DSC, real-time FTIR and rheology

The curing kinetics of UV-curable powder coatings based on commercial unsaturated polyesters were monitored using photo-DSC, Real-Time FTIR-ATR and a modified rheometer equipped with a UV source. The effect of physical and chemical factors on curing such as type of photoinitiator, photoinitiator concentration, temperature and atmosphere of curing were evaluated. Coatings containing amounts of photoinitiator from 0.5 to 10 wt% were cured at different temperatures in less than 10 s reaching conversions approximately of 60%. The increase of the temperature of curing reduces the final conversion and also the rate of polymerization due to the chain transfer process and depolymerization that dominates the photopolymerization at high temperatures. The reactivity of the photoinitiators was similar for all the studied photoinitiators apart from benzophenone that was found to be the slowest initiator.     

Spatial and temporal evolution of the photoinitiation rate for thick polymer systems illuminated by polychromatic light: selection of efficient photoinitiators for LED or mercury lamps

BACKGROUND: Four common free radical photoinitiators were evaluated for use in thick photopolymerizations illuminated with a medium‐pressure 200 W mercury–xenon arc lamp and a high‐intensity 400 nm light‐emitting diode (LED) lamp. For each photoinitiator/lamp combination, the spatial and temporal evolution of the photoinitiation rate profile was analyzed by solving the set of differential equations that govern the light intensity gradient and initiator concentration gradient for polychromatic illumination. RESULTS: The simulation results revealed that two of the four photoinitiators evaluated were ineffective for photoinitiating thick polymer systems. The photoinitiator bis(2,4,6‐trimethylbenzoyl)‐phenylphosphine oxide, in combination with the 400 nm LED lamp, was shown to be the most efficient photoinitiator/light source combination for photoinitiation of thick systems. CONCLUSION: The results show that some photoinitiators commonly used for photopolymerization of thin coatings are ineffective for curing thick systems. LED light sources provide advantages over traditional mercury lamps, and may have tremendous potential in the effective photoinitiation of thick polymer systems. Copyright © 2008 Society of Chemical Industry     

Colour and gloss properties of pigment‐printed synthetic leather using an ultraviolet‐curable water‐borne polyurethane acrylate binder and two photoinitiators at different ratios

This study reports on the colour and gloss properties of pigment‐printed polyurethane‐based synthetic leather using an ultraviolet (UV)‐curable water‐borne polyurethane acrylate binder and two types of photoinitiators (Omnirad 819 DW and Omnirad 500) at different ratios. The UV curing of printed synthetic leather samples was conducted with gallium and mercury lamps, either singly or in combination, at three different power levels. Chemical changes in the cured films because of the polymerisation of the UV‐curing process were analysed by Fourier Transform‐infrared spectroscopy, which showed that the polymerisation reaction occurred after UV curing in both the clear and in the pigmented films. The Omnirad 500 photoinitiator is more effective in surface curing and the Omnirad 819 DW photoinitiator is more effective in deep curing. The Omnirad 500 photoinitiator caused the gloss values to drop significantly, especially in the formulation including both photoinitiators, Omnirad 819 DW and Omnirad 500, at a 1:2 ratio, respectively. In the formulation including a higher ratio of the Omnirad 819 DW photoinitiator, higher gloss values were obtained compared with the formulation including a higher ratio of the Omnirad 500 photoinitiator. Considering all the results, the highest gloss value of 20.96 was obtained with samples printed with the formulation of the two photoinitiators at an equal ratio (1:1) cured under a gallium/mercury lamp combination at a power level of 90 W/cm. Moreover, the highest K/S value of 10.86 was obtained with samples printed with the formulation of the two photoinitiators at an equal ratio cured under the gallium lamp at 90 W/cm.     

聚氨酯型高分子硫杂蒽酮光引发剂的制备及性能研究

通过三种二异氰酸酯、2-（2,3-二羟基）丙氧基硫杂蒽酮（HPTX）及N-甲基二乙醇胺(MDEA)进行逐步聚合反应,将硫杂蒽酮结构及共引发剂胺结构引入到同一高分子链上,得到侧链含有硫杂蒽酮,主链含有共引发剂胺的聚氨酯型高分子光引发剂。傅立叶红外变换光谱和核磁共振氢谱证实了高分子光引发剂的结构。紫外光谱证实了高分子链的结构对硫杂蒽酮单元的最大紫外吸收几乎没有影响。用光致差示量热计（photo-DSC）研究聚氨酯型高分子光引发剂引发聚氨酯丙烯酸酯树脂（PUA）的光聚合反应,发现PU-IMTX是本文合成的引发剂中引发PUA光聚合最有效的光引发剂。     

Recent developments in photoinitiators

A new photoinitiator, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide (1), has been developed for industrial applications. The absorption of this bisacylphosphine oxide (BAPO) compound in the near UV-Vis range is significantly higher than that of hitherto known photoinitiators for UV curing. Investigation of the photochemistry of 1 revealed the efficient formation of four radicals, which can all initiate polymerization. Since the photoreaction is accompanied by the destruction of the chromophore responsible for absorption in the near UV-Vis, photobleaching of the long wavelength absorption is observed and the photoinitiator does not impart yellowing in the cured lacquer. Studies using FTIR and RTIR techniques showed that these features result in a higher conversion of acrylic double bonds than obtained with other photoinitiators in formulations containing a high loading of rutile type titanium dioxide pigments. These findings were confirmed by application tests in different white pigmented coatings. Further, the new photoinitiator allows the fast curing of thick pigmented layers, which makes it suitable for use in pigmented furniture coating. This new class of high performance photoinitiators is expected to promote the development of UV curable white coatings of high opacity and other applications where light in the near UV-Vis range is essential for curing. A liquid containing 25 parts of the BAPO photoinitiator 1 and 75 parts of 2-hydroxy-2-methyl-l-phenyl-propan-l-one (2) is an excellent technical and economical solution for most applications.

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紫外光固化含硫密封剂的制备及性能

以聚硫代醚橡胶为基础胶,利用Thiol-ene点击反应制备了紫外光固化含硫密封剂。考察了光引发剂种类和用量以及烯烃种类、多元硫醇种类等对硫化后密封剂力学性能、热分解温度、玻璃化转变温度的影响。结果表明,相比于光引发剂184,光引发剂1173的固化效果更好,固化后的密封剂热稳定性更佳,且随着光引发剂用量的增加,密封剂的力学性能和热稳定性均下降,光引发剂1173的用量宜为0.03份（质量,下同）。采用三丙二醇二丙烯酸酯（TPGDA）作为固化剂固化的聚硫代醚密封剂力学性能较好,而且随着TPGDA用量的增加,密封剂的力学性能和热稳定性均上升,TPGDA的用量宜为1.00份。多官能度硫醇的加入可提高密封剂的交联度及玻璃化转变温度。     

Photocrosslinkable modified vegetable oil based resin for wood surface coating application

An acrylated epoxidized linseed oil (AELO) was synthesized from epoxidized linseed oil through ring opening of the oxirane group using acrylic acid as ring opening agent. The occurrence of the acrylate group and the ring opening of oxirane group was monitored using FT-IR spectroscopy. The AELO was mixed with three different photoinitiators at two different concentrations. Wood surfaces were coated with the mixtures, subsequently cured under UV light and the resulting surface properties of the coated samples gloss, scratch resistance, solvent resistance, and coating adhesion were characterized. The efficiency of the photoinitiators and the influence of their concentration on the rate and the extent of the curing were studied by curing the AELO mixtures under a monochromatic wavelength of 365 nm and measuring absorption spectra during the cure by real time FT-IR spectroscopy. The decrease of absorption in the measured spectra at 1406 cm⁻¹ was used to calculate the conversion of acrylic double bonds with increasing time of UV light exposure to obtain information on the cure kinetics for each photoinitiator and concentration.