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Understanding BPA-non-intent resin technology in food contact metal packaging coatings / Linqian Feng in COATINGS TECH, Vol. 16, N° 6 (06/2019)  

[article]  inCOATINGS TECH > Vol. 16, N° 6 (06/2019) . - p. 28-37 Titre : Understanding BPA-non-intent resin technology in food contact metal packaging coatings Type de document : texte imprimé Auteurs : Linqian Feng, Auteur ; Andrew Detwiler, Auteur ; Jeffrey Clauson, Auteur ; Abraham Boateng, Auteur ; Hongkun He, Auteur ; Goliath Beniah, Auteur ; Thilanga Liyana Arachchi, Auteur ; H. Williams Chip, Auteur Année de publication : 2019 Article en page(s) : p. 28-37 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Aliments -- Emballages Anticorrosion Bisphénol A -- Suppression ou remplacement Couches minces Emballages métalliques Essais (technologie) Essais de résilience Evaluation Formulation (Génie chimique) Résistance chimique Spectroscopie d'impédance électrochimique Index. décimale : 667.9 Revêtements et enduits Résumé : Consumer and regulatory pressure to replace bisphenol-A (BPA)-based materials in food contact metal packaging coatings has increased in recent years. Regardless of the controversy around BPA, consumers expect canned foods to be free of substances perceived to have negative health impacts while maintaining current shelf life and flavor characteristics. To address the market needs, formulators must innovate to deliver BPA-non-intent (BPA-NI) solutions that can meet or exceed the performance of BPA-based materials. This presents a challenge with regard to improving the resistance to food sterilization and stability during pack testing, and simultaneously balancing mechanical performance that allows the BPA-NI coating to withstand the aggressive canning process. One response to these technical challenges has been the development of BPA-NI polyester resin technology through innovation on a monomer basis. This monomer innovation provides protective performance attributes such as resistance to corrosion and chemical attack, while enabling flexibility and adhesion through innovative resin and formulation design. Fundamental techniques such as electrochemical impedance spectroscopy (EIS) and cathodic disbonding were employed in combination with industrial fitness-for-use evaluations to demonstrate the improved protective barrier properties of novel non-BPA resins in formulated coatings. In addition, hydrophobicity and interfacial properties were studied to understand the impact of resin structure on coating performance from both experimental and computational perspectives. Applying this suite of methods and analysis builds strong structure-property correlations as part of a resin development strategy for novel non-BPA resins in metal packaging coating applications. Note de contenu : - EXPERIMENTAL PROCEDURES : Materials and sample preparation - Testing and evaluations (Electrochemical impedance spectroscopy (EIS) - Cathodic disbonding test - Food simulants and retord) - Computational modeling - RESULTS AND DISCUSSION : EIS and corrosion mechanisms - Stage zero : Dry film - Stage 1 : Foodsimulant absorption - Stage 2 : Corrosion initiation - Stage 3~4 : Pore/breakthrough formation and delamination - Time-based corrosion resistance - Interface and adhesion - Fig. 1 : Hydrolysis of model dihexanoate ester (hexanoate-glycol-hexanoate) compounds at 130°C - Fig. 2 : 2—(a) Cathodic disbonding schematic and (b) lab setup of cathodic disbonding experimental setup - Fig. 3 : Equivalent circuit model corresponding to a Bode plot with no time-constant (Stage zero corrosion) - Fig. 4 : Equivalent circuit model corresponding to one time-constant in a Bode plot (Stage I corrosion) - Fig. 5 : Equivalent circuit model corresponding to two time-constant (Stage II corrosion) - Fig. 6 : Equivalent circuit model corresponding to a coated metal with Warburg character (Stage III ∼ IV corrosion). Schematics (a) and (b) correspond to equations (5) and (6), respectively - Fig. 7 : Effect of exposure time on the EIS Bode plot for low-Tg low Mn Control B based clear PU - Fig. 8 : EIS Bode plot to compare Resin A vs Control A in clear PU formulation, as well as Resin A in gold benzoguanamine phenolic after 5 h of exposure in LAS food simulant - Fig. 9 : ime-based corrosion resistance of white PU coatings formulated with Control A, Control B, Resin A, and Resin B resins in 2% lactic acid food simulant for (a) 1st 48-h interval and (b) 2nd 48-h interval. Ten hours of relaxation time was given before the 1st and 2nd test intervals. Corrosion resistance is identified by the impedance value at 0.1 Hz - Fig. 10 : A comparison of corrosion resistance of white PU coatings formulated with Control A, Control B, Resin A, and Resin B resins after 106 h, in 2% lactic acid food simulant -Fig. 11 : (a) LogP values calculated for glycol (G1)-terephthalic acid (T)-glycol (G2) trimer model compounds, where EG=ethylene glycol, BG=butylene glycol, PG=propylene glycol, NPG=neopentyl glycol, DG=diethylene glycol. (b) Hildebrand solubility parameters calculated from molecular dynamics simulations. The color codes are used to rate the values, where Green=smallest value and Red=greatest value - Fig. 12 : EIS bode plot to compare Resin A vs Control A in clear PU formulation after 12 days of exposure in LAS food simulant - Fig. 13 : Images of clear PU coatings formulated with Resin A and Control A (a) after 3% acetic acid retort and (b) after cathodic disbonding test whereby 5V was applied for 60 sec - Fig. 14 : Quantifying cathodic disbonding failures of Control A-based clear PU coatings through pixels counting - Table 1 : Details of BPA-NI polyestser resins utilized in this study - Table 2 : Details of formulation components utilized in this study - Table 3 : Formulation details of gold benzoguanamine phenolic formulation - Table 4 : Formulation details of white and clear PU formulations En ligne : https://drive.google.com/file/d/1GM1X2P5qhHB9ENgQzeyxlyuJg2J5yzEO/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32719 [article]

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Polysilazanes / Yang Wang in COATINGS TECH, Vol. 16, N° 6 (06/2019)  

[article]  inCOATINGS TECH > Vol. 16, N° 6 (06/2019) . - p. 38-45 Titre : Polysilazanes : Binders that make a difference to surfaces Type de document : texte imprimé Auteurs : Yang Wang, Auteur ; Ralf Grottenmuller, Auteur ; Theresa Lorenz, Auteur Année de publication : 2019 Article en page(s) : p. 38-45 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Anticorrosifs Anticorrosion Essais accélérés (technologie) Liants Polysilazanes Résistance au rayonnement ultraviolet Résistance aux conditions climatiques Revêtements -- Additifs:Peinture -- Additifs Revêtements anti-graffitis Revêtements organiques Stabilité thermique Index. décimale : 667.9 Revêtements et enduits Résumé : Polysilazanes are pre-ceramic polymers with a silicon-nitrogen backbone. In recent years they have developed as a high-performance binder in protective coatings for transportation vehicles, commercial and residential buildings, and industrial plants. This article reviews their structure-property relationship and highlights their performance in high-temperature, surface hardness, weathering and corrosion protection, and anti-graffiti applications. Note de contenu : - Synthesis and process - Heat stability - Surface Hardness - Weather and corrosion resistance - Anti-graffiti properties - Coating uniformity - Fig. 1 : Polymer structures for PHPS and OPSZ, where R is H, CH3, CH=CH2, other alkyl, or aryl groups - Fig. 2 : Polymer structures for PHPS and OPSZ, where R is H, CH3, CH=CH2, other alkyl, or aryl groups - Fig. 3 : The two curing routes for OPSZ, where R1 and R2 are H, CH3, CH=CH2, other alkyl or aryl groups - Fig. 4 : Thermal stability evaluation of polysilazanes. Panel A shows the results of TGA for polysilazanes and two commercial silicone resins. All materials were dried at 120°C for four hours before TGA to simulate the thermal stability of their coatings. Panel B shows a stainless-steel exhaust pipe coated with both PHPS and OPSZ-based TBC. Panel C compares the visual appearance of a coated and uncoated exhaust pipe after pyrolysis at 1000°C for one hour in air. Panels B and C were obtained from the Royal Society of Chemistry and Motz et al. at the University of Bayreuth with permission - Fig. 5 : Characteristics of surface hardness for PHPS and OPSZ coatings. Panel A displays data of surface hardness for PHPS coatings on silicon substrates cured at different temperatures. These coatings have a film thickness of 1–1.2 μm. The hardness was measured via pencil hardness (in blue bars), Martens hardness (orange dots), and indentation resistance (black dots). The dots lines are guides for the eyes. Panel B shows a reference scale of pencil hardness, Martens hardness, and indentation resistance by using a bare glass and PMMA substrate. Panel C shows the anti-scratching property for a ∼3 μm thick OPSZ coating in clearcoat applications, and Panel D shows a similar performance for pigmented coatings. Both pigmented coatings have 17 wt% of pigment loading, a film thickness of 10–12 μm, and the right panel has 40 wt% polysilazane as a binder. Crockmeter test was performed by using an Atlas AATCC Crockmeter with 3M Wet-or-Dry 281Q rubbing cloth - Fig. 6 : Panel A shows two steel substrates after a 10-day water condensation test at a constant humidity of 50%. They have an electrochemically deposited white basecoat with a film thickness of 15–20 μm that partially covers the substrates. The substrate on the left has a 3–4 μm thick polysilazane-based clearcoat, while the one on the right does not. Panel B shows a similar comparison of coated and uncoated areas on a steel substrate after three days of HCl vapor exposure at room temperature [a beaker of HCl solution (37 vol%) was placed in the test chamber]. The coating thickness is about 2 μm - Fig. 7 : Panel A is a comparison of contact angle and surface energy for polysilazanes and three common binder materials, including nitrocellulose lacquer, acrylates, and polyurethanes. Also shown in Panel A is the value of the polar and dispersive component of surface energy, and surface energy is a sum of the polar and dispersive component. Panel B shows water drop shapes and contact angle measurements on a neat polysilazane coating and on a formulated polysilazane coating with other surface additives - Fig. 8 : Panel A is a marker test to demonstrate the ink repellency and easy-to-clean properties for a polysilazane based clearcoat. The inset shows the results after cleaning with a dry towel. Panel B is the result of an anti-graffiti test performed on a similar coating according to ASTM D6578, where level 1—dry cloth, level 2—mild detergent solution, level 3— limonene-based cleaner, level 4—isopropanol, and level 5—methyl ethyl ketone, n.c.—not cleanable - Fig. 9 : Three-dimensional surface morphology scans for a bare steel substrate (A), an OPSZ-based clearcoat on a steel panel (B), and a similar coating on a glass substrate (C). The polysilazane coating thickness is about 15 μm and 10 μm on the steel and the glass substrate, respectively - Table 1 : DIN/EN/ISO tests that OPSZ-based coatingsz have successfully passed - Table 2 : OPSZ coating performance before and after artificial weathering and UV stability test En ligne : https://drive.google.com/file/d/1KuEizt3Csd6O2NpcxCtM9uj10C1GeiwC/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32737 [article]

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Durability improvement underlies much coating innovation in COATINGS TECH, Vol. 16, N° 6 (06/2019)  

[article]  inCOATINGS TECH > Vol. 16, N° 6 (06/2019) . - p. 46-52 Titre : Durability improvement underlies much coating innovation Type de document : texte imprimé Année de publication : 2019 Article en page(s) : p. 46-52 Langues : Américain (ame) Catégories : Durée de vie (Ingénierie) Revêtements organiques Index. décimale : 667.9 Revêtements et enduits Résumé : The main objective of most coatings is to both protect and decorate. The balance that must be achieved between decoration and durability depends on application. Even so, the durability of paints and coatings continues to be a key performance characteristic. Therefore, improving durability is always an important goal of new product development efforts. The challenge is to provide performance over the longer term without increasing cost. On the other hand, significant cost savings can be obtained over the life of an asset by increasing coating durability, particularly for applications where the surfaces to be painted are difficult to access and coating application is more complex (monumental building exteriors, bridges, and offshore structures), for assets that must remain in service (trains and airport terminals), and where extensive surface preparation is required prior to coating. In most cases, the cost of the coating itself is relatively small compared to the costs of application, failure of the coating, and down time. Specialty coatings specifically designed to address the environmental conditions within which an asset exists will provide protection much more effectively than commodity-type coating solutions. Whether on a car, house, ship, bridge, tractor, or home appliance, reducing the rate of applied coating failure and the interval between repainting benefits all users. By extending asset lifetimes, coatings technology can be a significant contributor to facilitating resource, energy, and ultimately global sustainability. The key for coating manufacturers is to understand customer expectations before selecting their final formulations. Note de contenu : - Many drivers for greater durability - End use drives performance expectations - Testing challenges - Evolving coating technology - More work to do En ligne : https://drive.google.com/file/d/19mBbDiPNZndb7oWrY_4LPIhQaG_NU5N1/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32738 [article]

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Weathering and field defects / Clifford K. Schoff in COATINGS TECH, Vol. 16, N° 6 (06/2019)  

[article]  inCOATINGS TECH > Vol. 16, N° 6 (06/2019) . - p. 56 Titre : Weathering and field defects Type de document : texte imprimé Auteurs : Clifford K. Schoff, Auteur Année de publication : 2019 Article en page(s) : p. 56 Langues : Américain (ame) Catégories : Expertises Revêtements -- Défauts:Peinture -- Défauts Index. décimale : 667.9 Revêtements et enduits Résumé : My interest in weathering has mainly been in finding out what kinds of defects and problems occur after coatings have been out in the field, what causes these failures, and how they might be prevented. By the term field defects, I mean anything that hurts appearance or reduces the effective life of the coating. The list is long and includes loss of gloss, film erosion, chalking, blushing, blistering, corrosion, dirt pick-up, water spotting, acid etch, cracking, pinholing, fading, or other color problems, delamination and poor resistance to chipping and other impacts, scratching, abrasion, and biological attack. En ligne : https://drive.google.com/file/d/1k4S0zCkhClB8Y7yJS709BojOlbnpOWIn/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32739 [article]

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