Applications: ELAZTOBOND A250 Resin is utilized as an adhesion promoter, resorcinol replacement in RFS (Resorcinol-Formaldehyde-Silica) bonding systems, also known as HRH systems. The RFS system has been a proven adhesion mechanism for many years bonding natural and synthetic rubbers to treated and untreated fabrics, metals and rubbers. This adhesion system uses ELAZTOBOND A250 in combination with a methylene donor, typically hexamethylenetetramine (hexa) and silica. The typical loadings of ELAZTOBOND A250, hexa and silica are 2.5, 1.6 and 10 phr, respectively. Many compounders will adjust these loadings to obtain optimal bonding properties for their application. The ELAZTOBOND A250, hexa, and silica loadings typically fall within the following ranges: 2-4, 1-4 and 10-25 phr, respectively. This thermoplastic resin has replaced straight resorcinol in many applications due to improved dispersibility, adhesion performance and health concerns. ELAZTOBOND A250 is especially important in polychloroprene (CR) fabric adhesion, since normal resorcinol can scorch CR. Excellent methylene donor in CR is hexamethoxymethylmelamine (HMMM). It is very important that the ELAZTOBOND A250 is well dispersed in the first pass. The methylene donor is added during the second pass of the mixing process. Filler and accelerator adjustments may be necessary to maintain hardness and cure rate.

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