Synthesis and characterization of interpenetrating polymer networks with hyperbranched polymers through thermal-UV dual curing

The aim of this study was to investigate the possibility of using acrylated hyperbranched polyesters (HBP) as UV curable component in dual curing automotive applications. Dual curing is one of possible ways to obtain fast curing, scratch resistant coatings for use in OEM and car refinish applications. Dual curing systems, upon hardening, can give interpenetrating networks (IPNs).     

Comparisons of weathering performance of two automotive refinish coatings: A case study

The aim of this study was to compare the weathering performance of two commonly refinish coatings used in a domestic car manufacturer based on polyurethane (PU) and acid‐catalyzed alkyd‐melamine resins. The replacement of the alkyd‐melamine refinish with the PU system was shown to largely lower the reported fading behavior of the monocoat system. For better comparison between the refinish coatings, an original equipment manufacturers' (OEM) topcoat, cured at production line, was also used. Different characterization methods including DSC, atomic force microscopy, thermo gravimetric analysis, DMTA, and Fourier transform infrared spectroscopy were performed to elucidate the changes observed in the optical, mechanical, and weathering performance of studied coatings. It was found that the main reason for the inferior behavior of the acid‐catalyzed coatings compared with that of the PU and OEM was due to its low crosslinking density. The poor weathering resistance of the former coatings was attributed to its incomplete curing reaction and therefore, to its immatured film formation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

A complete new design for waterborne 2-pack PUR coatings with robust application properties

In this paper, a new approach to the paint composition design of WB 2-pack PUR coatings for car refinish application is presented. New hydroxy-functional binder emulsions are described that offer a better basis for the mixing process and the pot-life/reactivity balance with polyisocyanate hardeners. In addition, it will be shown that with these binder systems the overall balance of appearance, pot-life and curing speed can be enhanced to a very attractive level by the use of a well tuned catalyst package, allowing sufficient time for application, flow and de-aeration while offering the required fast curing characteristics as well. Thirdly, it will be shown how the aspects relating to undesired foam formation can be managed. Finally, the performance of low VOC paint compositions for car refinish application based on this new generation of WB 2-pack PUR system will be discussed.     

The influence of different components on interpenetrating polymer network's (IPN's) characteristics as automotive top coats

The aim of this study was to investigate the influence of different components of interpenetrating polymer networks (IPNs) on their behavior in dual curing automotive applications. Dual curing is one of possible ways to obtain fast curing, scratch resistant coatings for use in OEM and car refinish applications. Dual curing systems, upon hardening, represent interpenetrating networks (IPNs) [1]. IPN's were obtained using novel acrylate-terminated hyperbranched polyester with high functionality and compared to classical 2-pack polyurethane clear coat.     

紫外光固化设备与光固化合物的研究

涂层紫外光固化技术由于在能源节省、产品质量以及环保方面的优势，正在不断的迅速发展。本文综述了近年来辐照设备的进步，以及紫外光固化体系所涉及的单体、齐聚体和光引发剂的研究发展情况。     

快干汽车修补清漆的制备

从树脂合成、固化剂、催化剂等方面进行改善,制备的羟基丙烯酸树脂具有较好的干燥速度和优异的板面状态,经检测,在满足涂膜综合应用性能的前提下,能够使修补清漆喷涂后0.5 h即可达到不沾灰、不沾尘、光泽丰满、不失光的效果,在国内修补涂料市场发展前景广阔。     

Photo- and thermoinitiated curing of epoxy resins by sulfonium salts

A number of benzylthiolanium salts have been synthesized, analysed and evaluated by differential scanning calorimetry and viscosity measurements with respect to their potential use as thermal curing agents for epoxy resins. Over a wide range of Hammett constants a correlation exists between initial reactivity, shelf life and the electronic substituent effects of the benzyl group. A combination with arylsulfonium salts leads in singular cases to dual cure systems with attractive properties of thermal and UV induced curing. The sensitization of benzylthiolanium salts also leads to dual cure systems. This opens up new possibilities for UV curable epoxy resins in electronic applications requiring additional curing in shaded areas.     

UV curing of aqueous polyurethane acrylate dispersions. A comparative study by real-time FTIR spectroscopy and pilot scale curing

Real-time FTIR spectroscopy was used to study the chemical and physical factors, e.g., photoinitiator and temperature, affecting the UV curing of dried films from aqueous polyurethane acrylate dispersions. Poor conversion of the acrylate double bonds (67%) observed at room temperature can be overcome by irradiation at elevated temperatures. At 353 K almost complete conversion is observed, even with reduced photoinitiator content. Single or multiple UV-light flash experiments were performed to simulate technical parameters, e.g., cure speed and number of required UV lamps, with the help of RTIR spectroscopy. The results obtained were confirmed by pilot-scale UV curing experiments: one or, at most, two UV lamps of high intensity are sufficient for the curing process with respect to the double-bond conversion. The coatings based on the polyurethane acrylate dispersion show low sensitivity towards oxygen from air. Moreover, in comparison to UV curing under inert nitrogen atmosphere, a small “positive” effect on the conversion in the presence of air has been observed, which might be due to the contribution of peroxyl radicals or their decomposition products to curing. Permoserstra?e 15, D-04318 Leipzig, Germany.     

无溶剂双组分热喷快固化防腐涂料的研制与应用

针对我国石油沥青管道涂层的更新,及常用的环氧树脂类涂层和煤焦油磁漆涂层的补口,通过中间物质解决了石油沥青与环氧树脂的互溶性问题,研制出用于现场大修和补口的双组分厚浆型热喷快固化石油沥青聚氨酯涂料。采用高压无气喷涂,可作为新型重防腐涂料品种用于腐蚀防护领域。     

UV光-暗双重固化体系的研究进展

综述了UV光-暗双重固化体系的研究现状,总结了UV光-暗双重固化中的UV光固化反应和暗聚合反应类型,并重点介绍了UV光-湿气、UV光-热、UV光-空气和复合型4种双重固化方式。与单一的UV光固化技术相比,UV光-暗双重固化能够很好地解决单一UV光固化体系存在的固化不完全等问题,且UV光-暗双重固化技术制得的固化膜普遍具有化学稳定性好、耐侯性优异、环境污染小等优点。     

UV厌氧胶的制备及其影响因素研究

以聚氨酯丙烯酸酯(PUA)为基体、甲基丙烯酸-β-羟乙酯(HEMA)为活性稀释剂、异丙苯过氧化氢(CHP)为引发剂、N,N′-二甲基苯胺为促进剂、糖精为助促进剂、二苯甲酮(BP)/叔胺为光引发剂和对苯二酚为稳定剂,采用双引发体系和双固化[UV(紫外光)、厌氧固化]体系制备PUA基UV厌氧胶。通过单因素试验法优选出制备UV厌氧胶的最佳工艺条件。结果表明:当w(HEMA)=20%、w(CHP)=2%、w(光引发剂)=3.0%、w(N,N′-二甲基苯胺)=w(糖精)=0.8%和w(对苯二酚)=0.06%时,UV厌氧胶的综合性能良好,其光固化定位时间为8 s、剪切强度超过5 MPa。     

全球辐射固化产业概况(一)

本文简述了辐射固化发展史,辐射固化的技术优势,以及该技术的工业应用进展。介绍了UV/EB固化产业的基本结构和产业价值链。列出了美国、欧洲、日本和中国辐射固化的产业概况,生产原材料、涂料、油墨和胶粘剂的主要企业,以及制造UV固化装置和电子加速器(EB装置)的主要厂家。以及隨着经济全球一体化趋势,辐射固化产业内公司的重组与并购。     

Kinetic rate equation combining ultraviolet‐induced curing and thermal curing. I. Bismaleimide system

A novel and general kinetic rate equation combining ultraviolet‐induced (UV‐induced) curing and thermal curing was successfully derived from the conventional thermal‐kinetic rate equation. This proposed novel kinetic rate equation can be applicable to the curing system either simultaneously or individually by UV‐induced and thermal cure methods. This general kinetic rate equation is composed of the reaction order n, activation energy E_a, curing temperature T, energy barrier of photoinitiation E_Q, intensity of UV radiation Q, concentration of photoinitiator [I], and a few other parameters. The proposed equation was supported by experimental data based on the curing systems of 4,4′‐bismaleimidodiphenylmethane (BMI) and 2,2‐bis(4‐(4 maleimido phenoxy) phenyl propane (BMIP). The BMI and BMIP systems were isothermally cured at various temperatures, or simultaneously cured with varying intensity of UV radiation (wavelength 365 nm). Conversion levels for the various cured samples were subsequently measured with a FTIR spectrometer. The reaction order n = 1.2, activation energy E_a = 40,800 J/mol, and E_Q = 7.5 mW/cm² were obtained for curing BMI system. The reaction order n = 1.3, activation energy E_a = 53,000 J/mol, and E_Q = 9.1 mW/cm² were obtained for curing BMIP system. The values of n and E_a in the same curing system (BMI or BMIP) are irrespective of the curing method (either simultaneously or individually by UV‐induced and thermal cure methods). The salient results of this study show that UV radiation only enhances the initiation rate and UV ration do not influence the activation energy E_a. The experimental results are reasonably well represented by these semi‐empirical expressions.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

光固化ADGDE齐聚物的合成及特性

一缩二乙二醇二缩水甘油醚 (DGDE)与丙烯酸为原料 ,合成紫外光固化环氧丙烯酸(ADGDE)齐聚物。研究了催化剂用量、阻聚剂种类以及反应温度对反应速度和产物性能的影响 ,确定了合成工艺条件 ;用 FTIR表征了结构 ,并与通用双酚 A型环氧丙烯酸酯 (双酚 A型 AEP)比较了颜色、粘度和光固化特性。结果表明 ,ADGDE颜色浅、粘度仅为双酚 A型 AEP的 1 /1 0 0 0、光固化速度快     

Amino resin curable water reducible epoxy systems for automotive refinishing paints

The requirements on primer surfacers for application in vehicle refinish are described, and a waterborne amine curable epoxy system is introduced which meets these demands. The technical properties of this material are dependent on the time which passes between mixing and application. The impact of the aforementioned time on curing behaviour and film properties is followed by using dynamic mechanical analysis (DMA). The results indicate that correlations exist between several properties of the primer surfacer and its storage modulus E′.     

汽车修补漆用高固体分丙烯酸树脂的研究

随着全球降低涂料中VOC含量的环境法规出台,汽车修补漆正由传统溶剂型涂料向高固体分、水性化方向发展。通过丙烯酸单体、引发剂、链转移剂和合成条件的选择,开发了一种黏度适中的固体分达70%的丙烯酸树脂。该树脂与异氰酸酯固化剂配合应用于汽车修补漆,其性能完全达到市售国外同类树脂的水平。     

Dielectric method for monitoring the curing of polyester-melamine coatings

A method has been developed for monitoring the curing of coatings by means of dielectric measurements. The features of the method have been demonstrated by monitoring the curing of polyester-melamine coatings.

A sensor has also been developed, consisting of two comb-electrodes for the dielectric measurements and a temperature-dependent resistance for temperature measurements applied on a glass substrate. This has allowed the use of a thin layer of clear or pigmented coating and therefore approaches coating application practice. During curing, both dielectric properties (the dielectric permittivity and loss) and temperature have been measured.

From the dielectric data, the electrical conductivity has been calculated. The conductivity has been shown to depend on the degree of curing as well as on the temperature and the amount of solvent in the coating. Most of the solvent was evaporated before curing started. The increase in the glass transition temperature of the coating during curing has been determined using the WLF equation and the data for uncured and fully cured coatings. The glass transition temperature has been used as a measure for the extent of the reaction.

Curing of two different polyester-melamine coating systems has been monitored. The first system was cured both quasi-isothermally at 130 °C and at four different heating rates. The second system, a coil-coating system, was developed for fast curing at high temperatures. This system was cured at four different heating rates, and also flash cured by placing for a few minutes in an oven at a temperature above 250 °C.

For both isothermal curing and curing at a constant heating rate, the extent of the reaction has been determined with time. Assuming simple kinetics, the reaction constant and the order of the reaction have been determined.

It is concluded that the dielectric method is fast and convenient for monitoring curing, under conditions approaching coating application practice.     

Rheological studies of ultraviolet curing with an oscillating plate rheometer

The dynamic viscoelastic behavior during UV curing was studied for thin liquid films of epoxy acrylate prepolymer by the use of an oscillating plate rheometer. The dynamic viscosity rapidly increases after a certain period of irradiation, so that the UV curing process has the minimum exposure energy required to start polymerization. The minimum exposure energy markedly increases with increasing sample thickness; this results from the inconsistency of degree of curing in the direction perpendicular to the shearing surface. Since free radicals which initiate polymerization are formed by photochemical decomposition of initiator, the ability to cure a film depends on the light intensity at a given depth of the film. the attenuation of light in the film is primarily responsible for this inconsistency. When UV light is applied through a UV filter, the curing behavior is analyzed by a single exponential decay of light with depth because the curing is induced by absorption of a monochromatic light of 365 nm. On the other hand, when UV light from a UV lamp whose output spectrum is a continuum is directly applied, the curing behavior is explained by a combination of energy absorption at different wavelengths. In both cases, the theoretical curves of dynamic viscosity predicted in relation to spectral sensitivity show a good agreement with the experimental results.     

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.     

钝化2-乙基-4-甲基咪唑/环氧树脂低温固化体系研究

测定了三种α-甲基丙烯酸钝化2-乙基-4-甲基咪唑固化环氧树脂(EP)体系的凝胶时间及固化反应放热曲线,制定了EP固化体系的固化工艺条件,并对这三种EP固化体系的室温(20℃)储存特性及其浇铸体的综合性能进行了比较。结果表明:这三种EP固化体系均可在80℃时快速固化,浇铸体的固化工艺条件为80℃/4 h;当m(E-51)∶m(Eg-031)∶m(固化剂)=25∶25∶2时,EP固化体系预浸料具有最长的储存期(15 d),是综合性能优良的低成本复合材料制造用基体树脂,其弯曲强度、弯曲模量、冲击强度和热变形温度分别为109.3 MPa、3.0 GPa、7.76 kJ/m2和125℃。