Date of Award
Bachelor of Science
Pulp and Paper Technology
Dr. John Schulz
The importance of the continuous-film forming properties of the polymer via fusion upon heating is second to none. Yasuda states that it depends on the probability of two particles coalescing upon the application of heat versus the acceleration of the rate of removal of the disperse medium from the coating. Naturally it would seem that excessive rates of drying would not permit the adhesive to fuse, but it may also alter the distribution of adhesive throughout the coating in either case. Eames has suggested the effects of certain variables on the distribution of starch in starch-clay coatings, but the fact that starch insolubilization in coating formulations has proved rather difficult may influence its redistribution pattern upon drying.
From a theoretical standpoint the basic difference, the thermodynamic nature of the synthetic latex compared to the starch, may account for its difference in behavior in coatings applied on paper, especially when they are dried. One particular property of a latex which might reflect the latter is the "tackiness" of this type of adhesive.
Koller has suggested that the exposed part of the polymer molecule on the surface, not specifically bonded, may transfer forces to the coating wherein they are distributed. This may account for its stability in a coating to some types of energy.
For a rational approach to the evaluation of evidence which may be present, one must recall the diverse nature of paper, its varying properties, and the effect or influence of these taken as a totality or individually.
Gaspar, Lawrence A., "The Effect of Drying Conditions on the Surface Strength of Clay Coated Paper" (1962). Paper Engineering Senior Theses. 265.