1 May 1992 Polymer adsorption phenomena at the surface of delayed tack toner images in a photopolymer proofing concept
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Abstract
The photopolymers discussed here utilize a photo-initiated crosslinking mechanism to detackify the imaged regions. The latent image can be rendered visible by applying micron-sized pigmented toner particles to the tacky non-imaged areas of the photopolymer. Because the toner contains a solid plasticizer, it serves as a latent ink particle; heating activates the delayed tack state, characterized by prolonged adhesiveness. The creation of a liquid ink enables the rendered image to be printed onto a paper substrate. Photopolymer components, migrating into the melted toner layer, preferentially adsorb to the polymer/air interface after printing to paper, thus influencing the delayed tack adhesive state, during which excess plasticizer crystallizes. We examine competitive adsorption phenomena at the polymer solution/air interface, via a model four-component system, containing two oligomeric surfactant molecules from the film, both characterized by ethylene-oxide linkages, but distinguished by the fact that one, is linear, while2 the second, is composed of three branches. The concentrations of these long-chain constituents are varied in an otherwise constant bulk polymer solution of triphenylphosphate and the toner polymer simulating typical compositions in the actual melted toner layer. We apply two techniques of surface analysis, SIMS and ESCA (XPS), in order to reveal the identity of the adsorbing film species. Although both molecules are capable of a surface excess, the structure imposed upon the interfacial region is clearly different, depending on the excess surfactant at the surface. This difference is explained by assuming that the linear molecule lies flat on the surface while the branched oligomer adsorbs vertically. Specific SIMS/ESCA signals exhibit spectral intensities that are nonilnearly proportional to the bulk oligomer concentration; from the shapes of the adsorption isotherms, we deduce that the single chain surfactant is displaced at the surface by the branched oligomer.
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Gerard R. Pinto, Gerard R. Pinto, } "Polymer adsorption phenomena at the surface of delayed tack toner images in a photopolymer proofing concept", Proc. SPIE 1670, Color Hard Copy and Graphic Arts, (1 May 1992); doi: 10.1117/12.2322241; https://doi.org/10.1117/12.2322241
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