Journal of Photochemistry and Photobiology A: Chemistry 153 (2002) 129–133 Use of 2-(N-methyl-N-phenylamino)-1-phenylethanol as synergist in UV-curing applications Nergis Arsu ∗ The Department of Chemistry, Yildiz Technical University, Davutpasa, 34210 Esenler-Istanbul, Turkey Received 20 June 2002; accepted 24 June 2002 Abstract 2-(N-Methyl-N-phenylamino)-1-phenylethanol in formulations was used as an aminoalcohol to help reduce the effect of oxygen inhibition and to act as synergist with a Type II initiator. When the aminoalcohol in the formulation containing Trimethylolpropane triacrylate (TMPTA) is replaced by the NMDEA at the 10% level, the same amount of cure is obtained after one pass as when 1% aminoalcohol is used. It was found that the aminoalcohol was efficient at reducing oxygen inhibition and act as an excellent synergist for isopropylthioxanthone. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Aminoalcohol; Synergist; UV-curing; Photoinitiators 1. Introduction UV-curing is finding application in the manufacture of a wide range of products [1], e.g. compact discs [2], optical fiber [3–5], printing [6,7], production of electronic compo- nents [8,9], floor tiles, etc. The physical characteristics of the coatings produced by UV-curing have to meet many different criteria with the application being so varied. These criteria are in the main meet by choosing the appropriate resin(s) and prepolymer(s) for the system but also it is im- portant to have the correct initiator system and in order to achieve the right cure speed, and stability of the coat- ing to light, etc. [10–13]. Free radical mediated polymerisa- tion processes dominate the UV-curing market accounts for >80% of the market/despite the fact that oxygen inhibition of cure, reduces cure speed and has a deleterious effect a film surface properties [14–17]. We now describe the use of an aminoalcohol (1) in formu- lation to help reduce the effect of oxygen inhibition and to ∗ Tel.: +212-224-50-00; fax: +212-224-50-13. E-mail address: narsu@yildiz.edu.tr (N. Arsu). act as synergist with a Type II initiator. Use of the aminoalco- hol with a Type I initiator (2-Methyl-[4-(methylthio)phenyl] -2-morpholino-propane-1-one) in this case allows are to assess its effectiveness in reducing oxygen inhibition and when used with isopropylthioxanthone as a synergist. The aminoalcohol will react over the triplet state of the thiox- anthone to generation an -aminoalkyl radical which will initiate polymerisation 2. Experimental 2.1. Material 2-(N-Methyl-N-phenylamino)-1-phenylethanol was used as an aminoalcohol. 2-Methyl-[4-(methylthio)phenyl]-2- morpholino-propane-1-one (Irgacure-907) was supplied by Ciba Geigy Ltd. (Macclesfield) and Isopropylthioxanthone (ITX, a mixture of 2 and 4 isomers) and by International Octel Ltd. Trimethylolpropane triacrylate (TMPTA) was obtained from Aldrich and used as received. Sartomer 259 [polyethyleneglycol (200) diacrylate], Sartomer 344 1010-6030/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S1010-6030(02)00244-7