Failure prediction of waterborne barrier coatings during folding / Yaping Zhu in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 18, N° 4 (07/2021)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 18, N° 4 (07/2021) . - p. pages 1117-1129 Titre : Failure prediction of waterborne barrier coatings during folding Type de document : texte imprimé Auteurs : Yaping Zhu, Auteur ; Douglas W. Bousfield, Auteur ; William Gramlich, Auteur Année de publication : 2021 Article en page(s) : p. pages 1117-1129 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Analyse des défaillances (fiabilité) Matériaux -- Propriétés barrières Modèles techniques Pliage (mécanique) Revêtements -- Fissuration Revêtements en phase aqueuse Index. décimale : 667.9 Revêtements et enduits Résumé : Adding pigments into waterborne barrier coatings improves barrier properties and cost-effectiveness but increases the risk of crack formation during folding. Crack formation is affected by pigment shape, aspect ratio, and concentration; however, the exact mechanism for these effects is still not well understood. In this work, a systematic model was used to understand the influence of the paper and coating thickness, the latex and pigment modulus, the pigment shape and aspect ratio, and pigment concentration on the failure of waterborne barrier coatings during folding. A finite element method-based model was solved with a commercial package to simulate the folding process. These simulations were compared to experimental results to verify the key parameters that affect coating failure. High paper and coating thickness, pigment loadings, pigment aspect ratios, and modulus differences between latex and pigment increased the likelihood of failure. Experiments and models using lower modulus spherical plastic pigments were more difficult to fail than coatings made with higher modulus kaolin. The maximum strain for coatings bent to a set curvature was the smallest when the modulus of latex and pigment were similar. The model agreed closely with experimental results for two pigment types at various pigment loadings. Note de contenu : - METHODS : Model setup - Modeling general coating systems - Modeling experimental systems - Bending experiments - Comparing model and experimental results - RESULTS AND DISCUSSION : Shape and aspect ratio effects - Modulus effects - Paper and coating thickness effects - Comparison of simulation and experiment - Table 1 : Material properties in model - Table 2 : Model parameters to compare to experiments DOI : https://doi.org/10.1007/s11998-021-00465-1 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-021-00465-1.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36218 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
22969	-	Périodique	Bibliothèque principale	Documentaires	Disponible

Forces generated by web peeling for printing and coating applications / Harrison Gates in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 12, N° 5 (09/2015)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 12, N° 5 (09/2015) . - p. 899-913 Titre : Forces generated by web peeling for printing and coating applications Type de document : texte imprimé Auteurs : Harrison Gates, Auteur ; Douglas W. Bousfield, Auteur Année de publication : 2015 Article en page(s) : p. 899-913 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Pelage Revêtements Tags : 'Tensioned  web'  Peeling  Coating  Printing  'z-Directional  forces' Index. décimale : 667.9 Revêtements et enduits Résumé : The tensile forces that act on a web in printing and coating applications are important in situations where the web may delaminate or break. A model is proposed that uses lubrication expressions to describe the fluid flow in the thin fluid layer combined with a force balance on the web to describe the peeling event. A novel experimental method is described that measures the forces to separate a tensioned web from a surface with a viscous fluid between them. Forces are measured for various parameters such as viscosity, web tension, separation velocity, fluid volume, and fluid geometry. Dimensionless expressions are developed to correlate experimental results. Web deformation and forces are found to be influenced by a thin air film between web and bottom plate. These initial forces are found to be larger than later peeling forces unless something is done to allow air to flow between the web and the lower plate. Low web tension and stiffness are found to reduce the maximum force. The model predicts the measured forces within the expected accuracies. However, the model overpredicts the forces for large patch areas and thin films; this is likely caused by a cavitation mechanism or be three-dimensional flows for these large patch areas. Simplified expressions are generated to correlate the peeling forces for a wide range of experimental parameters. Note de contenu : - Model development - Numerical methods - Model predictons DOI : 10.1007/s11998-015-9731-y En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-015-9731-y.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=24690 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
17467	-	Périodique	Bibliothèque principale	Documentaires	Disponible

A method to model web trajectory and release in forward roll coating / Harrison Gates in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 14, N° 5 (09/2017)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 14, N° 5 (09/2017) . - p. 957-964 Titre : A method to model web trajectory and release in forward roll coating Type de document : texte imprimé Auteurs : Harrison Gates, Auteur ; Douglas W. Bousfield, Auteur Année de publication : 2017 Article en page(s) : p. 957-964 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Enduction au rouleau Lubrification Modèles mathématiques Index. décimale : 667.9 Revêtements et enduits Résumé : The trajectory of the web at the exit of a roll coating operation can influence the quality of the final coating. While methods to model the web trajectory have been given in the literature, these methods are limited in various ways. A method is proposed to describe the web trajectory and the pressure distribution in the fluid at the exit of a forward roll coater. The Reynolds lubrication equations for the fluid are coupled with the web by a force balance on web node points. The fluid pressure in the coating layer generates forces on the web. These forces deflect the web. Integration in time gives the web dynamics. The angle that the web is pulled from the nip and the tension are found to influence the pressure pulse in the divergent section of the nip to a large extent. Low tensions lead to a second pressure pulse followed by a sub-ambient or tack pressure. Pulling the web at various angles from the nip can cause the tack pressure to increase or decrease. Pressure pulses are predicted that are comparable to measurements by a laboratory device. Note de contenu : - Fig. 1. Configuration at the exit of a forward roll coating nip. The web can deform before the coating layer splits. a is the takeoff angle of the web, and xp is the distance away from the nip that this point is applied. The center of the nip is taken as x = 0 - Fig. 2. Experimental device to measure the influence of a web on the nip dynamics. The rubber-covered roll is to the left of the steel roll on the right. In normal operation, the rubber-covered roll would be in contact with the steel roll and rotates in the clockwise direction - Fig. 3. Dimensionless pressure distribution predicted when the web is pulled straight from the nip for various tensions for h*i = 0:01 and x*p = 2.0. On the right, the case for T* = 10 by itself for clarity - Fig. 4. Web trajectories for various tensions when the web is pulled straight from the nip for various tensions and x*p = 2. Note that the y-axis is enlarged compared to the x axis - Fig. 5. Dimensionless pressure distribution for even lower web tensions for the same conditions as in Fig. 2 - Fig. 6. Results for positive (downward) takeoff angle of 20°, with the take-up point being x*p = 2.0 for h* i = 0.01. Pressure profiles are shown on the left. Web trajectories on the right. Note that at T* = 100, the web follows the top roll surface some distance - Fig. 7. Same as Fig. 5, but for a negative angle of 20°, with the web being pulled upward from the nip. Left side is the pressure distribution, and the right side is the web trajectories - Fig. 8. Measured pressure distribution in a laboratory device that had a tensioned web DOI : 10.1007/s11998-017-9938-1 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-017-9938-1.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=29124 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
19230	-	Périodique	Bibliothèque principale	Documentaires	Disponible

The influence of barrier pigments in waterborne barrier coatings on cellulose nanofiber layers / Mohammed Al-Gharrawi in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 19, N° 1 (01/2022)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 19, N° 1 (01/2022) . - p. 3-14 Titre : The influence of barrier pigments in waterborne barrier coatings on cellulose nanofiber layers Type de document : texte imprimé Auteurs : Mohammed Al-Gharrawi, Auteur ; Rachel Ollier, Auteur ; Jinwu Wang, Auteur ; Douglas W. Bousfield, Auteur Année de publication : 2022 Article en page(s) : p. 3-14 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Aliments -- Emballages Cellulose La cellulose est un glucide constitué d'une chaîne linéaire de molécules de D-Glucose (entre 200 et 14 000) et principal constituant des végétaux et en particulier de la paroi de leurs cellules. Eléments finis, Méthode des Matériaux -- Propriétés barrières Nanofibres Revêtements en phase aqueuse Revêtements organiques Index. décimale : 667.9 Revêtements et enduits Résumé : Layers of cellulose nanofibers (CNF) have great potential to be used in food packaging applications because of their oxygen and grease barrier properties. However, because of their sensitivity to moisture, they likely will need to be used in a layered structure with water vapor barrier layers. Waterborne barrier coatings (WBBC) have the potential to provide this water vapor barrier, but their performance on paper with a CNF layer has not been described in the literature. Paper that had a CNF layer was coated with three different WBBC with various levels of two different barrier pigments to improve the water vapor barrier properties of these systems. The effective diffusion coefficient of these systems was obtained by fitting the data to a two-layer diffusion model. A finite element code was used to predict the flux rate of water vapor through the barrier layers in the presence of a barrier pigment. The dangers of samples “blocking” in production have been tested as well as grease barrier properties. The presence of the CNF layer on paper is shown to improve the performance of the water vapor barrier layer, in some cases, by a factor of six. Adding barrier pigment to the WBBC improves barrier properties at low concentration by 15%, but as the concentration of pigment increases, the barrier properties decrease. The water vapor transmission rate does not decrease to the same order of magnitude as expected from simple theoretical models and the finite element calculations. This result likely is linked to fine bubbles in the coatings that are hard to remove or other defects that are generated during coating or drying. Barrier pigments remove concerns around blocking. All samples had good grease barrier properties. Note de contenu : - Table 1 : Ranking system for blocking test - Table 2 : The values of effective moisture diffusion coefficient Dc in coatings obtained from fitting equation (1) for various pigment types and concentrations for polymers A, B, C. Values are in m2/s × 1010 DOI : https://doi.org/10.1007/s11998-021-00482-0 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-021-00482-0.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37140 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
23313	-	Périodique	Bibliothèque principale	Documentaires	Disponible

---

1 (1 - 4 / 4)