Resorcinol Formaldehyde Latex Research Articles

Some Mechanical Properties of Resorcinol-Formaldehyde Latex (RFL) Tire Cord Adhesive

Films of resorcinol-formaldehyde latex (RFL) films were made by casting on mercury. The tensile stress-strain curves and tensile and bending moduli were determined for films with different heat-curing conditions and different resin/latex ratios. The heat treatments (240° for 30 min conditions were more severe than in normal hot-dipping and vulcanizing) showed no significant change on the mechanical properties of the films. Changes in the latex/resin ratio produced gradual (not sudden or stepwise) changes in the mechanical properties. The dynamic Young's modulus and loss factor for a standard formulation film from -20°C to +120°C showed small changes, indicating a one-phase system of resin and latex. This evidence was supported by microscopic and electron microscopic evidence. Standard RFL film was shown to be a tough material of adequate extensibility (16%) and a modulus (2.3 × 106 g. cm-2) Intermediate between that of rubber skim stock and nylon tire cord. Its mechanical loss factor shows that it does not contribute unduly to the heat generated in a tire.

Role of adhesive–substrate compatibility in adhesion

AbstractFor substrates such as polyesters having limited capacity for hydrogen bonding or other specific interactions, thermodynamic compatibility of the substrate and adhesive is shown to be a key factor in promoting bondability to the substrate. Such compatibility occurs, as shown by Abere, when the cohesive energy densities (CED) or solubility parameters (δ = √CED) of substrate and adhesive are matched. Investigations with polyester film‐adhesive‐film model systems with the use of a variety of nonpolar (hydrocarbon) and polar (chlorinated compounds, ethers, esters) adhesives illustrate how compatibility promotes bondability to poly(ethylene terephthalate). The poor adhesion of polyester fibers to resorcinol–formaldehyde–latex (RFL) adhesives is attributed to the incompatibility of resorcinol (δ = 16.0) with the polyester (δ = 10.3). Adhesion to RFL was improved by substituting the more compatible n‐hexyl resorcinol (δ = 12.5) for resorcinol in RFL adhesives. Currently, the best adhesive systems for polyester tire yarns are those (e.g., isocyanate–epoxy) involving formation of urethane polymers having matching δ values with poly(ethylene terephthalate).