Isocyanate-functionalized latexes: Film formation and tensile properties

Abstract

Latexes functionalized with isocyanate groups were prepared by carrying out the emulsion terpolymerization of dimethyl meta-isopropenyl benzyl isocyanate (TMI) with methyl methacrylate and n-butyl acrylate. The film formation of these latexes and the tensile properties of the resulting latex films were studied. The effect of TMI concentration on the film properties was investigated. The locus of the isocyanate groups in the latex particles was controlled by using different polymerization processes. The locus of the functional groups was found to greatly influence the tensile properties of the latex films. Triethyl amine was used as an external catalyst to cure the TMI polymer films. One-component self-curable systems capable of undergoing crosslinking at ambient temperatures were developed by incorporating small amounts of methacrylic acid into the recipe. These systems exhibited significant improvement in tensile properties upon curing. In addition, the shelf-stability of these latexes was found to be excellent.

Synthesis of Self‐Crosslinkable Water‐Borne Pressure Sensitive Adhesives

“…They concluded that the NCO groups were evenly distributed throughout the particles under starved, semi‐batch conditions. The tensile properties of films prepared from those latexes gave a clear indication that TMI was contributing to crosslinking . Although they used a different surfactant (sodium dihexyl sulfosuccinate, MA‐80), a lower BA/MMA ratio (≈60/40; wt./wt.)…”

“…Mohammed et al reported that higher concentrations of NCO groups at particles' surface had a negative effect on the shelf storage stability of TMI latexes . The proximity of those groups to water made them more susceptible to hydrolysis, resulting in the loss of colloidal stability.…”

“…After this time, excess toluene was removed with a pipette and the weights of the swollen samples were registered. For the calculation of M c , the molecular weight between adjacent crosslink points, the method of Mohammed et al was followed. They applied the following equations based on the Flory–Rehner equilibrium swelling theory: where W o and W s are the weights of the dried and swollen samples, respectively; ρ p is the BA/MMA (95/5, wt./wt.)…”

Effects of crosslinking on adhesion behavior of waterborne polyurethane ink binder

“…Crosslinking contains one-component and two-component crosslinking. The common crosslinkers for two-component crosslinking mainly include carbodiimide [13,14], polyaziridine [15,16], and isocyanate [17][18][19]. One of the most important and pragmatic one-component crosslinking is the internal crosslinking, which implies the incorporation of polyfunctional monomers.…”

Studies of Dimethyl Meta‐Isopropenylbenzyl Isocyanate (TMI) for Preparation of Ambient Cross‐linkable Latexes—Stability of NCO Groups in Latex Form

“…This is assumed to be due to a catalytic effect on NCO hydrolysis by COOH groups in MAA repeat units rather than to direct reaction between NCO and COOH groups because COOH groups are lower in the hierarchy of reactivity towards NCO groups compared to water. [27] When acetic acid (2 wt% based on total monomer in the formulation) was added to the B20-NA as-prepared latex (which did not contain MAA) immediately before casting the latex (this mixture being coded B20-NA-AA), the rate of NCO loss increased only by a factor of approximately two. Thus the rate of loss of NCO remained much lower than for the latexes in which MAA was incorporated.…”