Isocyanate cross-linked

Figure 41. Residual gloss and AE%b values for isocyanate-cross-linked polyacrylate resins that contain 15wt% Vossen Blau 2000 (older pigment type which has been replaced by Manox Blue 460 D) relative to the binder and 15 wt% Ti02 (rutile) relative to the iron blue pigment after 1000 h fast exposure to UV [3.193] a) Without clearcoat b) With clearcoat but without UV protection c) With clearcoat and UV protection...

In some instances such as in isocyanate cross-linked coatings, the amount of moisture present must be taken into account in formulating calculations. Cellulose esters are packaged with very low moisture content however, if exposed to the atmosphere, cellulose ester powder or flake will regain moisture. The amount gained is dependent upon the relative humidity and the cellulose ester type, as illustrated in Table III. To ensure a consistent composition, all cellulose esters should be stored in low relative humidity surroundings or kept in a closed container. 

Caradol Shell Polyhydroxy compound for isocyanate cross-linking... 

Isocyanates. Whereas polyamines and thiols cure epoxy compounds via their epoxy groups, isocyanates cross-link high molecular mass epoxy resins via their hydroxyl groups to form polyurethanes. The reaction takes place at ambient temperature. These combinations cure more rapidly and at lower temperature than epoxy resins cured with polyamines. 

Originally the adhesive system consisted of an aqueous poly(vinyl alcohol) solution with an isocyanate cross-linker. At this stage the common name was Aqueous Polymer Isocyanate (API) [3]. Further developments including use of different types of polymer emulsions, like poly(vinyl alcohol) (PVA), ethyl(vinyl acetate) (EVAc), styrene butadiene rubber (SBR) or acrylic-styrene (AcSt) emulsion, led to adhesives systems with improved performance, hence today the common abbreviation is EPI [4, 8]. The isocyanate cross-linking agent has also been further developed to improve the compatibility and the reactivity with the water-based component, thus several different types are now available for use in EPI adhesives. 

EPI adhesives are thermoplastic polymer dispersion adhesives combined with isocyanate cross-linking that gives a degree of thermosetting characteristics and properties. The adhesives are complex, multiphase systems with a number of physical processes and chemical reactions occurring in parallel during the gluing process. 

Mulik S, Sotiriou-Leventis C, Leventis N (2008) Macropoious electrically conducting carbon networks by pyrolysis of isocyanate-cross-linked resorcinol-formtildehyde aerogels. Chem Mater 20 6985-6997... 

Mulik S, Sotiriou-Ireventis C, Ireventis N (2(X)8) Macroporous Electrically Conducting Carbon Networks by I yrolysis of Isocyanate-Cross-Linked Resorcinol-Formaldehyde Aerogels Chem Mater 20 6985-6997... 

Mulik S, Sotiriou-Leventis C, Leventis N (2008) Macroporous Electrically Conducting Carbon Networks by Pyrolysis of Isocyanate-Cross-Linked Resorcinol-Formaldehyde Aerogels. Chem Mater 20 6985-6997. Tanaka S, Katayama Y, Tate M, Hillhouse H, Miyake Y (2007) Fabrication of continuous mesoporous carbon films with face-centered orthorhombic symmetry through a soft templating pathway. J Mater Chem 17 3639-3645. 

Shigley J E, Mischke CRM (2(X)1) Mechanical Engineering Design 6 ed. New York, p 1206 Meador M A B, Capadona L A, MacCorkle L, Papadopoulos D S, Leventis N (2007) Structure-property relationships in porous 3D nanostructures as a function of preparation conditions isocyanate cross-linked silica aerogels. Chem Mater 19 2247-2260... 

Vivod S L, Meador M A B, Nguyen B N, Quade D, Randall J (2(X)8) Di-isocyanate crosslinked aerogels with l,6-bis(trimethoxysilyl)hexane incorporated in silica backbone. Polym Preprints 49 521-522 Vivod S L, Meador M A B, Capadona L A, Sullivan R M, Ghosn L J, Clark N, McCorkle L, Quade D J (2(X)8) Carbon nanofiber incorporated silica based aerogels with di-isocyanate cross-linking. Polym Preprints 49 306 307... 

Katti A, Shimpi N, Roy S, Lu H, Fabrizio E F, Dass A, Capadona L A, Leventis N (2006) Chemical, physical and mechanical characterization of isocyanate cross-linked amine modified silica aerogels. Chem Mater 18 285-296. 

Katti, A., N. Shimpi, S. Roy, H. Lu, E.F. Fabrizio, A. Dass, L.A. Capadona, and N. Leventis. 2006. Chemical, physical, and of isocyanate cross-Linked amine-modified silica aerogels. Chemistry of Materials 18(2) 285-296. 

The clearcoat is referred to as a 2K clearcoat when an isocyanate cross-linking agent is utilized as the crosslinker. The isocyanate must be added to the hydroxy functional acrylic just prior to spray application to prevent premature gellation (crosslinking). For this reason, the two-part mixing is referred to as 2K. Cure conditions for isocyanate crosslinked systems range from ambient (car refmish technology) to 250°F for 30 minutes. 

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