[雙語(yǔ)翻譯]--外文翻譯--紫外線固化水性丙烯酸酯涂料（英文）

1、www.coatingstech.orgUV-Radiation Curing of Waterborne Acrylate CoatingsC. Decker and I. Lorinczova?—Ecole, Nationale Supérieure de Chimie de Mulhouse*Presented in part at the RadTech Europe Conference in Berlin, No

2、vember 3-5, 2003. * Département de Photochimie Générale (CNRS), 3 rue Werner, 68200 Mulhouse, France. ? Université de Bratislava (Slovaquie).A kinetic study of the ultrafast curing of water-based acry

3、late resins upon UV irradiation was conducted by means of in- frared spectroscopy. Under intense illumination, the crosslinking polymerization was found to occur in the dried film within less than one second to generate

4、a totally insoluble polymer. The influence of a number of critical factors on the polymerization rate and cure extent has been investigated, namely the type of photoinitiator, the chemical structure of the acrylate funct

5、ionalized oligomer, and the sample temperature. Coatings obtained from emulsions undergo a faster and more extensive polymerization than coatings obtained from dispersions, because of a greater molecular mobility in the

6、soft low-modulus polymer formed. Very hard coatings were produced by the UV curing of dispersion-type acrylate resins, espe- cially when the UV irradiation was performed at 80°C on the sample emerging from the dryin

7、g oven. Tg values up to 120°C were reached when such resins were UV-cured at ambient temperature as 1-mm thick plates, because of the large amount of heat released during such ultrafast polymerization. UV-cured coat

8、ings made of aliphatic polyurethane-acry- lates proved to be very resistant to accelerated weathering in the presence of adequate light stabilizers.Keywords: Photoinitators, FTIR, ATR, polymerization, acrylics, polyureth

9、anes, UV, EB, radiation cure, hardness, scratch resistance, water-based, weatherability, reaction kinetics247JCT Research, Vol. 1, No. 4, October 2004Light-induced polymerization of multifunctional monomers or oligomers,

10、 also called UV-radiation curing, is one of the most efficient methods to syn- thetize rapidly highly crosslinked polymer networks at ambient temperature.1-7 Upon intense illumination, a sol- vent-free acrylic resin can

11、thus be transformed within a fraction of a second into a solid polymer, totally insoluble in the organic solvents and very resistant to heat and me- chanical treatments. Because of its distinct advantages, this environme

12、nt-friendly technology has found a large variety of industrial applications, mainly as fast-drying protective coatings, printing inks, adhesives, and compos- ites, as well as in photolithography to produce printing plate

13、s, microcircuits, and optical disks.5,7,8UV-curable resins typically consist of a photoinitiator, a functionalized oligomer, and a monomer serving as a re- active diluent to adjust the formulation viscosity.1 The photoin

14、itiated crosslinking-polymerization process can be represented schematically as follows:The multifunctional acrylate monomers commonly used as diluents still have a strong odor and may cause eye and skin irritation. More

15、over, they are enhancing the shrinkage process which yields internal stresses, and they may be responsible for curling and poor adhesion. Water- based UV-curable systems appear as a promising alterna- tive to overcome th

16、ese drawbacks, water being used as the only diluent. The formulation viscosity can, thus, be re- duced to the precise level required for spray or rolling ap- plication, simply by adjusting the water content. Moreover, wa

17、ter-based UV-cured coatings have been shown to combine the flexible properties of high molecu- lar weight polymers with the hardness of crosslinked acry- late polymers.9 The potential of water-based resins and their perf

18、ormance in UV-radiation curing has already been investigated.9-16 They proved particularly well suited to be used as screen inks and protective coatings for plastics, pa- per, and wood. We report here a new study on the

19、high- speed UV-curing of some commercial water-based acrylate coatings, by focusing on the influence of the photoinitia- tor and the functionalized oligomer on the polymeriza- tion kinetics, namely cure speed and cure ex

20、tent. The ef- fect of the kind of water-based resin used (dispersion or emulsion) on the viscoelastic properties of the UV-cured polymer will also be investigated, as well as the correlation existing between the degree o

21、f conversion and the poly- mer properties, in particular its hardness.only one minute to release 95% of the water in the emul- sion heated at 80°C, and two minutes for the dispersion, compared to 15 minutes and two

22、hours, respectively, at ambient temperature. In further experiments, the water- based coatings were dried at 80°C for five minutes or at ambient temperature for a few hours, so as to contain less than 2 wt% remainin

23、g water.Influence of the Photoinitiator on the UV CuringThe photoinitiators (PI) selected are partly soluble in water or consist of an aqueous dispersion; thus, they were added directly to the water-based resin before dr

24、ying and UV curing. Figure 3 shows the influence of the photoini- tiator (1 wt%) on the polymerization profiles of the for- mulation E-1 exposed to intense UV radiation (500 mW cm–2) at ambient temperature. The following

25、 PI ranking was obtained:Darocur 1173 < Esacure KIP < Irgacure 819 DW < Lucirin TPO-L < Irgacure 2959Similar results were obtained with the Laromer disper- sions, but the polymerization proceeded less extens

26、ively(40% conversion) because of mobility restrictions in the dry film. A faster and more complete curing was achieved by performing the UV exposure at 80°C. Table 2 reports the conversion values reached after one p

27、ass at a speed of 5 m/min (0.43 J cm–2) for the 25 formulations UV-cured at 80°C. For the aromatic dispersions (D-2 and D-3), the somewhat better performance of the acylphosphine ox- ides can be explained by the str

28、ong absorbance of these resins in the 250-300 nm wavelength range. The resulting radiation filter effect will be less pronounced with these photoinitiators where the absorbance extends up to 400 nm rather than with the h

29、ydroxyphenylketones which absorb precisely in the 250-300 nm wavelength region. The UV-cured dispersions, which give very hard polymers, contain a certain amount of residual acrylate double bonds (15% for Irgacure 2959 i

30、n sample D-1), a quantity which can be somewhat reduced upon further UV expo- sure. Complete polymerization was achieved for the coat- ing E-1, whatever the photoinitiator, because the Tg of the fully cured polymer is we

31、ll below 80°C.The acylphosphine oxide photoinitiators undergo a fast photolysis upon UV exposure, as shown in Figure 4 forUV-Radiation Curing of Waterborne Acrylate Coatingswww.coatingstech.org 249Figure 1—Chemical

32、formulas of photoinitiators used.Figure 2—Influence of the temperature on the drying of water-based acrylate coatings (dispersion ▲, emulsion ● ). Wet film thickness:50 µm.Figure 3—Influence of the photoinitiator (1