Wood Science and Pulp, Paper Technology Commons^™

Development Of Water-Based Ink System For Braille Printing, Saurabh Varma

Masters Theses

The most commonly used system of writing by and for blind persons is called Braille, named after its French inventor, Louis Braille (1809-1952). Braille is comprised of a rectangular six-dot cell on its end, with up to 63 possible combinations using one or more of the six dots. Braille is the only reliable method of literacy for blind persons, because it enables them to read and write by touch¹.

Currently, Braille is printed by special embossers that serve as a printing press. These embossers create Braille output when it is attached appropriately to computers. The speed of these …

Rheology Of Silica Based Inkjet Coatings And Their Filterability, Peeyush Tripathi

Masters Theses

Coating rheology has long been understood to be a key factor in the smooth operation and performance of a coater. As coaters run faster and formulations become more complex, the demands on a coating's rheology grow more stringent.

Silica based coating formulations present unique rheological challenges, thus providing the opportunity for coating formulators to improve their performance through rheological studies under various conditions of shear. Due to rheological restrictions (gelling), silica based coatings are generally applied at 25-26% solids which is very low as compared to calcium carbonate or clay based coating, at 68-70% solids. Consequently, any improvement in coatings …

Uv-Vis Spectral Analysis Of Spot Colors, Radovan Sporka

Masters Theses

Press return inks represent a continuous problem in printing industry. The best way of utilizing them is to mix them into new colors. Efficiently to do so, it is necessary to determine their composition first. The spot color inks for product gravure were analyzed using Perkin Elmer Spectrometer LAMBDA 900. UV/VIS/NIR analysis of mixtures showed rather similar course of ink spectra in ultraviolet and near infrared region. Thus, the VIS range from 400 - 700 nm was used for further analysis. The unique course of spectral curves of each pigment in visible region enabled successful qualitative analysis of two- and …

Lateral Migration Of A Solid Particle In Shear Flow, Wutthapong Jiraporncharoen

Masters Theses

Lateral migration of solid particles in shear flow is observed in various industrial applications. Suspensions in a blade coater, a device used to apply coating pigment to a base paper to improve paper properties, is an example. Particle hydrodynamics will affect the quality of coated paper and runnability of the coater especially when the speed of the coating machine is very high or the pigment concentration is increased.

Many factors will affect the particle migration. The wall repulsion or lubrication effect forces the particle away from a wall to the channel center. The inertial effects are increased by increasing the …

Enzymatic Deinking Of Flexographic Water-Based Inks, Somporn Chaiarrekij

Masters Theses

Introduction

In recent times, environmental concerns have led to the development of water-based flexographic and rotogravure inks. One of the major concerns for water-based inks is their deinkability. Wash deinking of flexographic water-based ink is much more effective than flotation deinking; however, it has two major disadvantages. It consumes large amounts of water and gives a lower yield than flotation due to the loss of fines and fillers in the effluent (1).

Influence Of Starch Molecular Weight And Sodium Alginate On Silicone Holdout For Release Papers, Peter Suchy

Masters Theses

This research was focused on determining the influence of applying one type of potato starch of various molecular weights on silicone holdout. Also, combinations of potato starch with a rheology modifier, sodium alginate, of low, medium, and high molecular weight were studied. The base paper employed was a commercially available paper generally used to manufacture release papers.

Sizing with low molecular weight potato starch is more effective for silicone holdout than sizing with high molecular weight potato starch. This study showed that the paper sized with low molecular weight potato starch has a smoother surface, lower permeability, and a smaller …

Assessing Silicone Holdout For Release Papers, Rudolf Haraga

Masters Theses

Silicone coating is widely used on papers that require low surface tension. Such papers are called release papers and are used in label, food, and packaging applications. Before silicone coating is applied, the base paper undergoes sizing procedures to smooth the surface and to cover voids present in the surface of the paper substrate. After the base paper is properly sized, it is silicone coated. This makes the surface of the base paper have a low surface energy. Therefore, when a second adhesive paper is applied to the base paper, the second adhesive paper can be easily recovered from the …

Hot Melt Inks For Rotogravure - Formulation, Printability And Rheology, James Atkinson

Masters Theses

A new generation of phase change, or hot melt ink will be formulated. This ink was solid at ambient temperature and liquid at the moment of printing. Inks will be formulated on the basis of polyethylene and Ethyl Vinylacetate chemistry. Inks were printed using a Meyer rod for screening printability study. Selection of the best formulations will be done on the basis of reflective density, specular gloss, mottle, and rub resistance. Screened inks having best properties were printed on the Moser laboratory sheetfed proofing press. More detailed printability analysis was done after Moser printing, including dot structure analysis, tone gradation, …

Effect Of Size Level And Fiber Coarseness On Ink-Jet Printability Of Size Press Coated Paper, Falguni Mehta

Masters Theses

In recent years, matte coated paper has enjoyed wide spread usage for ink-jet applications. The coating performance is strongly influenced by base sheet properties including fiber coarseness and base sheet absorbency. Base sheet absorbency, which is elevated in terms of internal sizing, is a crucial property of ink-jet paper.

The objective of this research was to evaluate the influence of size level and fiber coarseness on ink-jet print qualities. A secondary objective was to examine the size reversion phenomena and to quantify the effect of size level, pigmented coating, and fiber coarseness on size reversion.

The results showed that the …

The Influence Of Base Sheet Sizing On The Print Quality Of Matte Coated Ink Jet Papers, Saurabh K. Halwawala

Masters Theses

The most recent developments in ink-jet papers have been related to coating aμd pigment technology. Silica is the preferred pigment for matte coated ink-jet papers. Besides being expensive, the high surface area and porosity of this pigment limits the percentage coating solids to less than 30-35%, which increases production cost due to higher dryer loads. Thus, a need exists to develop a new generation of pigments. The objective of this research was to evaluate the effect of base sheet absorbency on the surface, as well as print properties of matte coated ink-jet papers using a new pigment capable of being …

Development Of A Photoinitiator Blend For Uv Cured Inks And Coatings, Madhu Bansal

Masters Theses

The purpose of this study is to develop a new standard blend of photoinitiators, having properties of low odor, high solubility, faster curing, and being efficient for pigmented as well as for clear systems. In the process, we expect to understand the behavior of mixtures of photoinitiators and their resulting UV spectra. An important first step is to prepare different blend with different photoinitiator and characterize them on cure basis. Curing properties were studied by the KMnO₄ yellow stain density test. The absorption range in the UV spectra was measured for each Photoinitiator with methanol and acrylate as background …

An Investigation Into The Influence Of Common Fillers On Color Reversion Of Bctmp Pulp, Joseph N. Mikowski

Masters Theses

Recent advances in the pulping and bleaching of high-yield pulps, particularly bleached thermomechanical pulp, have made these pulps suitable replacements for bleached kraft pulps. Unfortunately, these high-yield pulps are not appropriate for making high-grade papers because of their tendency to yellow. Extensive efforts have been made to reduce the yellowing, but none of the methods that have been investigated have been at once both practical and economical.

This study investigated the ability of common pigments used in the paper industry to reduce the extent of yellowing of an 80/20 blend of bleached chemithermomechanical and bleached softwood kraft pulp. The effectiveness …

Borax As Internal Stock Additive In Papermaking, Nejib S. Yousef

Masters Theses

The effect of borax on strength property of paper has been investigated in different ways. The use of borax either improved the physical properties or assisted in the reduction of refining energy to significant level.

The study of borax in the presence of precipitated and ground calcium carbonate was accomplished by using white water recycling. In the absence of retention aids, recycling of white was a necessary condition for the retention of ash content. As the ash content increased the strength property decreased. But the presence of borax slowed down the detrimental effect of fillers.

Sizing development progressively improved especially …

Fundamental Study Of The Coating And Basesheet Influences On Gloss In Relationship To Coated Inkjet Papers, Raja Ramakrishnan

Masters Theses

The use of fumed metallic oxides for glossy ink jet media offers alternatives to expensive cast coated and extruded film methods. Fumed metallic oxide pigments provide a high internal porosity and packing porosity that enable the rapid diffusion of liquid inks into the coating layer. Their small particle size (0.1-0.3μm), enable the development of gloss. However, calendering is needed to develop gloss values in the range of cast coated and extruded film grades.

Calendering of coated sheet reduces production speed, adds additional handling and rewinding cost (if performed off-line) and reduces the bulk and porosity of the coating layer, consequently …

Effect Of Calendering On Flexographic Print Ability Of Linerboard, William P. Woods

Masters Theses

Today's corrugated board end user demands a higher quality than ever. Retailing techniques are moving toward so-called ''value-added packaging," which consists of high quality printed packaging that works to sell the product from the shelf. To preserve'its dominance in the corrugated market, the flexographic printing industry must find new ways to cost effectively satisfy the new demands.

One possibility is the use of an additional calendering step to give the linerboard better printability. This study evaluated two different types of calenders: the shoe (extended nip) calender and the hot/soft nip calender (Appendix A). The test material was commercially produced linerboard, …

Effect Of Various Starch Sources On The Silicone Holdout Of Release Paper, Chandrasekaran Duraiswamy

Masters Theses

Siliconized papers are widely being used from food and packaging industry to pressure sensitive label industry and their use has increased considerably over the last decade. Surface and structural properties of the sheet influence the silicone hold out and release properties.

Surface sizing of the sheet is done prior to silicone coating. The objective of this research is to find their film forming capabilities, fluid hold out of various starches, and the effect of the various calendering process on the release properties was also studied.

No significant difference between the starch sources were observed, except for the modified com starch …

The Influence Of Fumed Metallic Oxides On Coating Structure And Their Relationships To Print Quality, Hyun-Kook Lee

Masters Theses

Aqueous-based coating for paper or paperboard applications use traditional coating pigments such as clay, calcium carbonate, and titanium dioxide. But, for matte coated ink jet papers, amorphous and gelled silicas are used due to their unique morphological properties, which are sponge-like in nature. The unique structure of these pigments provides an internal porosity and packing porosity which enables the rapid diffusion of liquid inks into the coating layer. The rapid uptake of the ink immobilizes the anionic dyes at the surface of the coating, allowing high optical print densities to be achieved.

The particle size of precipitated and gelled silicas …

Borax As A Strength Additive In Recycling, Siva Krishnagopal Devisetti

Masters Theses

The effect of multiple recycling on strength properties and fiber properties like strength of fiber, weighted average fiber length, fines percentage and water retention values were investigated in this study. Borax was used as a strength aid and swelling agent to improve the flexibility of fiber and strength of recycled paper. Bleached softwood kraft pulp was used to make the hand sheets and recycled repeatedly for up to four cycles. The main objectives were to evaluate the chemically treated pulp and untreated pulp at each stage of recycling, to study the effect of multiple recycling on strength properties of paper …

Use Of Boron Compounds To Reduce Phototyellowing Of Mechanical Pulps, Qilin Zhou

Masters Theses

Bleached chemithermomechanical pulps (BCTMP) are replacing chemical pulps such as bleached kraft pulp (BKP) in many paper grades. However, the loss of brightness that arises from exposure to light remains a significant impediment to the wider use of these pulps. Efforts have been made in reducing photoyellowing, but so far no universal, economical method has been found which converts high-yield pulp into a product with brightness stability comparable to that of a bleached chemical pulp.

This study evaluates the ability of sodium borate and/or boric acid to inhibit the yellowing process of paper that was made from BCTMP, with an …

Dimethyldioxirane In Tcf Bleaching Sequences, Nayereh Mahdavi

Masters Theses

The use of chlorine containing bleaching process creates various organic compounds such as chlorinated furan, dioxin, and AOX (adsorbable organic halogen). The human and aquatic life has been affected with the formation of these chlorinated organic compounds. EPA is proposing new regulations to impose discharge limits on the conventional pollutant materials of the bleaching effluents.

The objective of this research was to evaluate two TCF (Total Chlorine Free) bleaching sequences that use hydrogen peroxide and DMD on oxygen delignified hardwood kraft pulp. In one of the sequences, the DMD stage (A) was used prior to the hydrogen peroxide stage (P), …

Effects Of Temperature Control On Gravure Packaging Inks, Rodrigo Sosa

Masters Theses

It is well known that variations in ink temperature cause a variation in color density and viscosity. The viscosity of almost all liquids decreases with increasing temperature. In this research project, three different ink temperatures were selected to measure the effects of temperature control on solvent and ink consumption and on printability. Two colors were selected (magenta and cyan) and two heat exchangers were constructed to cool and/or heat the ink.

It was found that variations in ink temperature cause variation in solvent and ink consumption. As the temperature of the ink increases, solvent consumption and ink consumption increase, but …

Mathematical Model Of Paper Discoloration By Ink Particles, Zbigniew W. Slotwinski

Masters Theses

The goal of this experiment is to investigate how changes in the size and number of ink particles will affect the final brightness of the filter pad.

It was assumed that any differences in brightness of the used Millipore filters were due to change in the average particle size, given the same mass of ink solids on each filter. However, such simplified interpretation of image analysis proved to be inadequate to solve this complex problem.

The correlation between the particle area, number of particles, and brightness drop was established using an algorithm based on the particle area and the square …

A Comparison Between Two Phase System And Single Phase System In Stiff Beveled Blade Coating By Measuring The Blade Forces, Ravi Mohan

Masters Theses

The effect of pigment particle interactions in a two-phase system on blade force is investigated. Three coating colors of 0%, 40% , and 55% solids, of the same high shear viscosity and density, were tested for blade force, blade run-in relationship. The Cylindrical Laboratory Coater was used to blade coat the coating on a polyester film. Blade deflection was measured by placing a probe in direct contact with the back side of the blade. A calibration plot between blade force and blade deflection was then used to determine the actual blade forces. A statistical analysis of the data reveals that …

Effect Of Precalendering On Surface And Printing Properties Of Coated Sheets, Hariharan Venkata-Chinnaswamy

Masters Theses

This study focuses on the effect of different types of precalendering on coated woodfree paper for surface and printing properties as well as coat weight distribution and binder migration.

Precalendering enhanced the gloss and reduced the roughness of the coated paper at all coat weights. In the case of post-calendered papers, any differential effect achieved through various types of precalendering was recovered during post calendering. The final porosity values of precalendered and uncalendered sheets were more dependent on the coat weight at the high coat weights (10-18 g/m² ). At low coat weights the type of precalendering influences the …

The Effect Of Ink Jet Coating Rheology On Screening, Burak Aksoy

Masters Theses

Ink jet coating formulations are becoming of increasing importance due to rapid expansion in digital printing. These coatings have very specific ink absorption requirements, which are fulfilled by using polyvinyl alcohol and silica as binder and pigment, respectively. These coatings have unique rheological behavior and often have problems in industry during the filtering process. In this work, an attempt was made to relate filter blocking to the rheological behavior of the coating. A series of coatings were prepared and their rheological properties characterized. The solids content and pigment selection of the coating were altered in order to adjust the coating …

Direct Measurement Of The Water Retention Of Coatings Under Shear, Mohana Sundaram Thiagarajan

Masters Theses

Coating water loss is one of the most critical concerns in coated paper production. The objective of this study was to determine directly the water retention value under dynamic conditions. The effect of shear rate on water transfer was documented for a delaminated clay coating color. The results showed a small change in water transfer at low shear rates, compared to the static condition. But at higher shear rate, the water transfer increased significantly. The water transfer increased with time, reaching an asymptotic limit at 300 seconds. This indicates that at higher retention time, the water transfer rate is reduced …

The Effect Of Drying And Rewetting On Single Fiber Flexibility For Chemical And Mechanical Pulps, Mark E. Dulemba

Masters Theses

Over the years, various attempts have been made to develop methods to measure fiber flexibility. In the course of developing test methods for fiber flexibility, various studies have been performed that measure the flexibilities of different wood pulps.

In this study, never-dried individual thermomechanical pulp (TMP) and bleached kraft fibers were mounted on the tip of a glass tube submerged in water and deflected by water flow. The deflection of the individual fibers was measured using a microscope and image analysis software. The fibers were then dried, rewetted, and the deflection was measured_again. This drying and rewetting cycle was repeated …

The Repulping Of Wet-Strength Paperboard, Angelo N. Melchiorre

Masters Theses

Beverage carrier paperboard containing the polyamide wet-strength resin is one type of fiber that is presently landfilled. In this study, it was repulped at a 15% consistency and a pH of 10 at 150° F. in a z-bar mixer. Hydrogen peroxide (HP), ammonium perswulfate (AP), sodium persulfate (SP) and dimethyldioxirane (DMD) were used during repulping. The HP was added at 1.0%, 2.5% and 5.0%, based on O.D. weight of the fiber. The remaining chemicals were added at the same oxidation equivalent. During repulping, the pulp was screened using a Britt Jar to determine percent yield over time. Samples were taken …

Effect Of Wire Gauge, Web Speed, And Coating Solids On Leveling Of Streaks In Rod Coating, Mukhtar A. Khan

Masters Theses

The behavior of coatings and their study is becoming more important in proportion to additional use of coated paper. Good coating is key to enhance print quality. Blade coating is quite common, but rod coating is coming back for the advantages it has over blade coating. The process of rod coating is simpler and maintenance is easier. Coatings at low solids can be applied with ease and the impurities are washed away by rod rotation. The surface profile of coating is a potential concern, due to streaks in the machine direction. If the coating is immobilized before the streaks heal, …

Influence Of Metal Ions On Brightness Reversion Of Mechanical And Tmp Pulps, Ajay K. Jain

Masters Theses

High-yield mechanical pulps possess high opacity, bulk, compressibility, and excellent printing properties as well. But these pulps are still not suitable for producing high-grade papers because of discoloration. The brightness with age may be due to the presence of lignin, hemicellulose (and even cellulose), resins, metal ions, and additives such as rosin, alum, starch, and other polymers.

This study includes the effects of different metal ions on brightness stability of wood, thermomechanical pulps, chemithermomechanical pulps, and alkaline peroxide mechanical pulps. Also studied were the influences of metal ions on bleached pulps towards brightness loss. The metal ions selected for this …