PMDI prepolymers for enhanced curing for production of wood composite panels / T. S. McCracken in COATINGS WORLD, Vol. 24, N° 1 (01/2019)  

[article]  inCOATINGS WORLD > Vol. 24, N° 1 (01/2019) Titre : PMDI prepolymers for enhanced curing for production of wood composite panels Type de document : texte imprimé Auteurs : T. S. McCracken, Auteur Année de publication : 2019 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Bois Conifères Construction sandwich Liants Panneaux de particules Pins et constituants Polyméthyl diphényl diisocyanate Procédés de fabrication Index. décimale : 667.9 Revêtements et enduits Résumé : The wood composite industry has been using PMDI since the 1970s, most notably in oriented strand board products. With current formaldehyde emission reduction initiatives, PMDI has been moving into the particle board and medium density fiberboard areas as well. The industry has been looking for a fast curing PMDI to compete with the catalyzed urea/melamine resins with the goal to reduce press times. When using PMDI for wood composites, the process comprises combining wood particles with a PMDI resin, followed by molding or compressing the coated combination of wood particles. PMDI prepolymers are useful as single component binders as they do not require separate catalyst or polyol streams to be metered into the resin at the mill facilities which would require additional personnel to monitor the process. The binders are advantageous in that they may be used to reduce press times without the addition of a catalyst, may be run with higher wood moisture contents, and provide longer shelf life (when stored properly) when compared to the other commonly known catalyzed wood binder systems. This paper looks at various single component PMDI’s reactivity and press time reduction results for laboratory produced panels. The data shows that the proper choice of prepolymer can allow for reduced press times for enhanced productivity and efficiency in panel production. Note de contenu : - EXPERIMENTAL : Lab panel plan - Panel nanufacture procedure - RESULTS AND DISCUSSION : Time and temperature reactivity - 541 vs. prepolymer - Reactivity rate comparison - Lab panel - Result - Fig. 2 : Lodige blender - Fig. 3 : Reactivity onset - Fig. 3 : Cure onset - Fig. 4 : 541 Temperature and Reactivity - Fig. 6 : Temperature and rate - Fig. 7 : Reactive rate profile - Table 1 : Panel conditions - Table 2 : Temperature rise compared to rate of temperature change - Table 3 and 4 : Temperature times - Table 5 : Lab panel results En ligne : https://www.coatingsworld.com/issues/2019-01-01/view_features/pmdi-prepolymers-f [...] Format de la ressource électronique : Html Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32506 [article]

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