Dynamic colorimetric properties of mixed thermochromic printing inks / Rahela Kulčar in COLORATION TECHNOLOGY, Vol. 127, N° 6 (2011)

[article]  inCOLORATION TECHNOLOGY > Vol. 127, N° 6 (2011) . - p. 411-417 Titre : Dynamic colorimetric properties of mixed thermochromic printing inks Type de document : texte imprimé Auteurs : Rahela Kulčar, Auteur ; Mojca Friškovec, Auteur ; Marta Klanjsek Gunde, Auteur ; Nina Knesaurek, Auteur Année de publication : 2011 Article en page(s) : p. 411-417 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Colorimétrie Encre d'imprimerie Thermochromie Index. décimale : 667.3 Teinture et impression des tissus Résumé : Leuco dye-based thermochromic inks reversibly change from the coloured to the discoloured state in a defined, comparatively wide temperature region. Inside this region, the colour of a sample depends on the temperature and thermal history, which is known as the hysteresis effect. The colour of such a sample as a function of temperature has the shape of a hysteresis loop. Commercially available thermochromic inks have different loops, narrow or broad, and their shapes range from approximately symmetric to highly asymmetric. These properties are also important in mixtures of inks. The hysteresis loop of a mixture reveals its binary nature if the individual pure inks have well-separated hysteresis. When inks with close-separated loops, i.e. with similar activation temperatures, are mixed together, the loop of the mixture fuses together into an apparently single loop. Our research shows that some of their dynamic colour properties could be predicted in advance. However, optic and colorimetric properties of mixtures are not additive. DOI : 10.1111/j.1478-4408.2011.00338.x Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12662 [article]

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Influence of dispersing additives on the conductivity of carbon black pigment dispersion / Nina Hauptman in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 8, N° 5 (10/2011)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 8, N° 5 (10/2011) . - p. 553-561 Titre : Influence of dispersing additives on the conductivity of carbon black pigment dispersion Type de document : texte imprimé Auteurs : Nina Hauptman, Auteur ; Marta Klanjsek Gunde, Auteur ; Matjaž Kunaver, Auteur ; marija Bešter-Rogac, Auteur Année de publication : 2011 Article en page(s) : p. 553-561 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Adsorption Conduction électrique Dispersions et suspensions Fourier, Spectroscopie infrarouge à transformée de Noir de carbone Index. décimale : 667.2 Colorants et pigments Résumé : The influence of dispersing additives on the electrical conductivity of carbon black pigments dispersed in an organic medium was studied. Two dispersing additives were examined in combination with two different carbon blacks, a conductive carbon black and a nonconductive one. These carbon blacks differ in the size of their aggregates and in the amounts of surface oxygen groups. Both of the additives form a monolayer when adsorbed on either of the pigment surfaces. FTIR studies showed that chemical bonding of one of the additives on the surfaces of both pigments had occurred. Conductivity decreases with increasing additive concentration, but in the case of the chemically bonded additive, the conductivity of the dispersion remained high even at higher additive loadings. This study helps in understanding the effects such additives have on the specific conductivity of composite materials that contain dispersed carbon black pigment particles. Note de contenu : EXPERIMENTAL : Materials - Size distribution of CB - Preparation of dispersions - Adsorption measurements - Conductivity measurements of suspensions - Infrared spectroscopy RESULTS AND DISCUSSION : Size distribution of CB particles - Adsorption - Specific conductivity of dispersions - FTIR studies of the dispersant's interactions with the CB surface DOI : 10.1007/s11998-011-9330-5 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-011-9330-5.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12231 [article]

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Light fastness and high-temperature stability of thermochromic printing inks / Mojca Friškovec in COLORATION TECHNOLOGY, Vol. 129, N° 3 (06/2013)  

[article]  inCOLORATION TECHNOLOGY > Vol. 129, N° 3 (06/2013) . - p. 214-222 Titre : Light fastness and high-temperature stability of thermochromic printing inks Type de document : texte imprimé Auteurs : Mojca Friškovec, Auteur ; Rahela Kulčar, Auteur ; Marta Klanjsek Gunde, Auteur Année de publication : 2013 Article en page(s) : p. 214-222 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Encre d'imprimerie Photostabilité Stabilité thermique Thermochromie Index. décimale : 667.2 Colorants et pigments Résumé : Thermochromic printing inks are known for their low stability under the influence of various external conditions, but the consequences of the phenomenon on dynamic colorimetric properties have not yet been analysed. In this work, thermochromic prints were exposed to light and heated at two different temperatures, 150 and 200 °C, for varying time periods. The changes to the dynamic colour properties of the samples were described. It was found that both exposure to light and heating to high temperatures degrade the dynamic properties of thermochromic inks; however, they have different effects on the colour hysteresis. The corresponding loops contract with light exposure and heating, which is best described by the area of the entire colour loop. Exposure to light broadens the corresponding loop, while heating makes it narrower. The chemical stability of inks after exposure was also analysed by forced oxidation applying weakly ionised oxygen plasma. Stability of thermochromic samples is a combined effect of the binder, the polymeric shell and the active core inside the pigment capsules. The results show that poor stability against light and high temperatures has different origins. Note de contenu : - MATERIALS AND METHODS : Materials - Measurements - Evaluation of dynamic colour - RESULTS : Light fastness - High temperatures DOI : 10.1111/cote.12020 En ligne : http://onlinelibrary.wiley.com/doi/10.1111/cote.12020/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18495 [article]

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Spectroscopic evaluation of the colour play effect of thermochromic liquid crystal printing inks / Maja Jakovlević in COLORATION TECHNOLOGY, Vol. 133, N° 1 (02/2017)  

[article]  inCOLORATION TECHNOLOGY > Vol. 133, N° 1 (02/2017) . - p. 81-87 Titre : Spectroscopic evaluation of the colour play effect of thermochromic liquid crystal printing inks Type de document : texte imprimé Auteurs : Maja Jakovlević, Auteur ; Branka Lozo, Auteur ; Marta Klanjsek Gunde, Auteur Année de publication : 2017 Article en page(s) : p. 81-87 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse spectrale Colorimétrie Cristaux liquides Encre d'imprimerie Thermochromie Index. décimale : 667.2 Colorants et pigments Résumé : Colour changes of a thermochromic liquid crystal (TLC) ink printed on a black substrate are clearly observed by the naked eye, and therefore it is reasonable to expect that every approach recommended for colour measurements of samples with solid colour would be appropriate. In addition, the published spectroscopic analyses of TLC inks do not provide any guidance or limitations for the measurement geometry. On the other hand, our study demonstrates that spectroscopic measurements of such samples are not so straightforward. When using the most simple and commonly used measurement equipment with a directional illumination and viewing approach, the temperature-dependent spectral features resolve in a narrow spectral region that gives only a small part of the colour play effect. Detection of the entire effect requires the use of integrating spheres, which spatially integrate the radiant flux reflected on a sample in any direction; better results are obtained by spheres of larger diameter. The comparision of spectroscopic and colorimetric results obtained when different measurement geometries are applied on the same sample may demonstrate certain properties of the liquid crystal material inside microcapsules and help in understanding some details of the optical properties of the ink layer. DOI : 10.1111/cote.12257 En ligne : https://drive.google.com/file/d/1pQIZ4jbwq63Oxmy3QfA8jE-YOJcGW4UA/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=27894 [article]

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