Moisture Crosslinking (Curing)
Patents with Abstracts
Curable compositions with moisture-curable functionality clusters near the chain ends
Controlled radical polymerization (hereinafter CRP), including single-electron transfer living radical polymerization (hereinafter SET-LRP) and atom transfer living polymerization (hereinafter ATRP), is a process which produces various polymer products, in high yield, with functional, non-terminated ends, with high molecular weights, and with a low polydispersity index. Thus, CRP has been employed to design a variety of polymer products. However, these polymer products typically produced through CRP resulted in curable products with functional groups at their terminal ends.
Known CRP polymers have cure speed limitations, as well as shear modulus values which are less than desirable for many applications. Moreover, these CRP polymers have less ability to be tailored for applications requiring flexibility, thermal resistance, fluid resistance and other desirable physical and chemical properties. Thus, there exists a need for a CRP polymer with increased functionality for curing which can lead to enhanced flexibility, thermal resistance, fluid resistance, modulus shear and strength as compared to known CRP polymers
Coffey et al of Henkel Corporation developed intermediate reactors with controlled radical polymerization. Controlled radical polymerization of a polymerizable compound, an initiator, a ligand, and a catalyst to a desired level of conversion is attained, but prior to complete conversion to obtain an intermediate polymerization product. This intermediate polymerization product containes a cluster of multiple reactive sites. The reactive groups can be (meth)acrylic groups, carboxylic acid groups, hydroxyl groups or alkoxy groups.
The polymer product prepared through SET-LRP may be reacted in such a way that pendant curable, including moisture-curable functionalities, may be introduced in clusters near the ends of the polymer chain. As such, the terminal end groups, which desirably may be functional, of the resultant polymer remain intact while further providing cluster functionality. The resulting functional polymers of the present invention may then be formulated into moisture-cure compositions. These moisture-cure compositions may exhibit superior cure time, as well as other advantageous and desirable characteristics.
Rapid deep-section cure silicone compositions
Ramakrishnan and Nesakumar of Momentive Performance Materials Inc., New York, developed siloxane polymers and zinc oxide and their uses in sealant formulations possessing rapid deep-section cure. This sealant consists of a) silanol-terminated diorganopolysiloxane; b) crosslinker for the silanol-terminated diorganopolysiloxane(s); c) a catalyst for the crosslinking reaction; d) a rapid deep-section curing amount of zinc oxide. The silicone sealant compositions of the present invention find application in insulating glass units as elements of windows, skylights, doors and related products. (RDC 7/27/2012)
Moisture curable isocyanate containing acrylic formulation
Harvey and Zhu of Illinois Tool Works, Inc., Illinois, developed a moisture curable acrylic formulation. The prepolymer has an average molecular weight of between 3,000 and 6,000 grams per mole and between 2 and 4 moisture curable functional groups of isocyanate or silane per prepolymer. A thermoplastic adhesive resin is also included within the formulation. When the prepolymer functional moieties are all silane, the thermoplastic adhesive resin is ethylene vinyl acetate resin. A silane molecule is provided within the formulation as an adhesion promoter and also affords a degree of storage stability through sacrificial reaction with water during storage. The resultant formulation achieves a shear strength of at least 10 pounds per square inch when applied to a thickness of 0.75 millimeters between a glass substrate and a vinyl article 15 minutes after application at 120 C in ambient atmospheric air. The formulation is well suited for the formation of a window assembly when applied intermediate between a substrate and a window article. (RDC 7/27/2012)
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Roger D. Corneliussen
Maro Polymer Links
Tel: 610 363 9920
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Copyright 2012 by Roger D. Corneliussen.
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** Date of latest addition; date of first entry is 7/27/2012.