Makoto Usuda

NMR analyses of polysaccharide derivatives containing amine groups

Amylose, amylopectin, hydroxyethylcellulose, methylcellulose, and cellulose were reacted with diethylaminoethyl chloride HCl salt and 3-chloro-2-hydroxy-propyltrimethylammonium chloride under aqueous alkaline conditions in order to introduce tertiary amine and quaternary ammonium groups into polysaccharides. Degrees of substitution were obtained from 1H- or 13C-NMR spectra of hydrolyzates, and distributions of diethylaminoethyl groups in polysaccharides were measured by 13C-NMR. Since amylose, amylopectin, and hydroxyethylcellulose were soluble in the reaction media, these three polysaccharides had higher reactivity for etherifications than cellulose. Methyl-cellulose, which has hydrophobic methyl groups, had as much reactivity as cellulose. Primary hydroxyl groups, C-6, of polysaccharides had the highest reactivity for diethylaminoethylation.

Studies on Flow Properties of Coating Colors. VII. Printability of Amphoteric Latex-Based Coated Paper.

The effects of electrostatic interaction between constituent particles in coating color was studied in terms of the structure of coating layer and the printability of resulting coated paper. Optical properties and printability was evaluated for coated papers prepared by using coating color containing amphoteric or anionic latex having the same composition of monomers but with different surface charge groups.The amphoteric latex-based coated paper can be characterized by the following features as compared with the anionic latex-based paper : 1) Higher air permeability and similar opacity.2) Significant increase in wet-pick resistance and slightly decreased dry-pick resistance.3) Simultaneous improvements in water-resistance and wet surface-ink receptivity.4) Superior ink receptivity and ink setting for various types of ink.These favorable features of amphoteric latex-based coated paper are considered to stem from the electrostatic interaction among latex particles, clay particles, and the fibers on the surface of base paper, through the prevention of binder migration to the surface of coating layer and permeation of binder into the base paper.

Studies on Flow Properties of Coating Colors. II. Electrostatic Interactions between Coating Color Components as studied by Electron Microscopy.

For the purpose of visualizing the interaction between latex and pigment particles by electron microscopy, a new fixation technique was introduced that can preserve the shape of latex particles during the drying process. The method consists of mounting a drop of highly diluted coating color on a Formvar-coated copper grid for transmission electron microscopy (TEM) and treating the solution on the grid with osmium tetroxide vapor in a dessicator. Metal coating of this grid provided a specimen suited for scanning electron microscopy (SEM).When the pH of sample suspension was adjusted by using phosphate buffer, the SEM observation revealed a striking difference in behavior between a conventional anionic latex and an amphoteric latex in aggregating tendencies with clay particles. While the anionic latex particles were dispersed nearly uniformly on the substrate at both acidic and alkaline conditions, the amphoteric latex particles were strongly adsorbed onto clay particles in acidic and nearly neutral conditions. These results suggest the effectiveness of using amphoteric latexes as a means to control the latex-pigment interaction in coating colors for improving flow properties and preventing binder migration.The pH dependences of viscosity and the sediment volume ratio of undiluted coating colors were consistent with the latex-clay interaction as indicated by SEM observation.