Date of Award

5-2014

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Polymers and High Performance Materials

Committee Chair

Jeffrey S. Wiggins

Committee Chair Department

Polymers and High Performance Materials

Committee Member 2

Sarah E. Morgan

Committee Member 2 Department

Polymers and High Performance Materials

Committee Member 3

James W. Rawlins

Committee Member 3 Department

Polymers and High Performance Materials

Abstract

The history of carbonless paper dates back to the 1940s. Before this, a carbon copy sheet was needed between sheets of paper to be able to produce one or more copies simultaneously during writing. The pressure from a pen or typewriter would help deposit the ink of the carbon paper onto the blank sheet of paper under the original written sheet to create a “carbon copy.” This method did however, have its disadvantages. Not only did it produce a limited number of copies, but it was also a messy process. So came the creative process of using microencapsulated dyes to make carbonless paper (Burrell, 2003, pp. 451-456). In this process, microencapsulated dyes are coated onto the back of the original sheet so when pressure is applied to the top sheet, it causes the microcapsules to rupture and form an image on the receiver sheet below. Under this capsule coating is a barrier coat or sub-coat, which is applied to the back of the original written sheet. The coating limits the encapsulated dye from absorbing into the original written sheet and increases the dye transferring onto the copy receiver sheet. In the barrier coating, latexes are used. Different chemical properties within the latex will make the barrier coatings perform differently (Mumford, 2007).

The goal of this research study was to test the structure-property relationships that determine the effects of commercial latexes and starch containing latex emulsions (SCEs) on the performance properties of the barrier coating (sub-coat) for paper. The testing of these property changes was performed on the thin film coating of varying pounds per ream on base stock 34lb Domtar paper. Six different latexes with mildly different chemical properties were tested. The rheological techniques used to evaluate the coating slurries include: water retention, viscosity, and pH testing. The performance measurement tests done on the basestock coated samples include: Oil resistance and absorption which were measured through K&N and Croda (Manders Red Drawdown) ink tests and also Sheffield porosity. In conclusion, Typewriter Intensity and Frictional Smudge testing was done to verify the performance results of the barrier coated and CB capsule coated sheets.

Through the performance and verification tests, some general conclusions were determined. These include: an increase in coat weight showed an increase in transfer efficiency and a smaller particle size latex created a better film and more sealed base stock sheet. This was shown not only in the porosity values, but also in the ink absorption results. It was also determined that the acrylonitrile containing latexes performed better due to the creation of a softer more flow-able latex. It was determined that DMF 5501, a commercial latex from Styron containing styrene butadiene copolymer with a low level of carboxylic acid groups, a high level of acrylonitrile groups, Tg 15 ̊C, and a particle size of 135nm, had the best performance when targeting the lowest coat weight, at 2lbs per ream. The smaller particle size and presence of both carboxylic acid and acrylonitrile groups proved to aid in this performance. An increase in binder efficiency was shown through testing, it is believed that both of the chemical groups present helped by binding the CB capsule coating to a greater extent to the base stock sheet. The smaller particle size aided in this binding by creating a better flowing more pliable latex which created an evenly formed barrier coat film. The porosity values results determined that DMF 5501 formed a better film, creating a more sealed sheet, hence a showing lower porosity value. The K&N and Croda Ink intensity values also showed that DMF 5501 performed best by showing highest ink intensity values on each base stock sheet. The performance verification tests determined that at only 2 lbs per ream of applied coating, DMF 5501 performed within the required standards set by Appleton Paper Inc., and if chosen, this latex could be used within the current carbonless paper product.

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