Production, Optimization, and Application of Printing Ink From Waste Carbon Sources
Chapter One
AIM AND OBJECTIVES OF THE STUDY
The aim of this study is to carry out laboratory synthesis and production of carbon black from sources such as spent automobile tyre, coal, carbon rod and furnace soot and their use in printing ink industry. The specific objectives of the study are:
- Conversion of spent tyres, carbon rod, coal, furnace soot to carbon black
- Production of printing ink using carbon black
- Quality assessment of the printing ink against industry standard
CHAPTER TWO
LITERATURE REVIEW
BACKGROUND
Printing inks are broadly distinguished by the printing process in which they are used. Letterpress and lithographic inks are known as paste inks and are of higher viscosity than the flexographic and gravure inks, which are called liquid inks. Printing inks are mixtures of three basic types of ingredients: pigments, vehic1es and additives. Pigments determine the colour of the ink, including its hue (shade) and strength, and also affect physical properties, such as flow characteristics (rheology), opacity (or transparency), fastness and bleed resistance. Vehicles serve as carriers for the pigment during the printing process and bind the pigment to the substrate. Additives may inc1ude any of a very large number of ingredients needed to impart specific characteristics to the ink, such as driers, waxes, plasticizers, antioxidants, lubricants, rheological agents and curing agents. Pigment is one of the essential components of ink. The most important pigment at all is carbon black, as it is the only pigment used in the manufacture of the most important printing ink, the black one.
Carbon black (also known as acetylene black, channel black, furnace black, lamp black or thermal black) is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, ethylene cracking tar, and a small amount from vegetable oil. Carbon black is a form of amorphous carbon that has a high surface-area-to-volume ratio, although its surface-area-to-volume ratio is low compared to that of activated carbon. It is dissimilar to soot in its much higher surface-area-to-volume ratio and significantly lower (negligible and non-bioavailable) PAH (polycyclic aromatic hydrocarbon) content. However, carbon black is widely used as a model compound for diesel soot for diesel oxidation experiments.47Carbon black is used as a pigment and reinforcement in rubber and plastic products.
Carbon black is ultrafine soot manufactured by the burning of hydrocarbons in a limited supply of air. This finely divided material (10 to 400 mµ in diameter) is of industrial importance as a reinforcing agent for rubber and as a colourant for printing ink, paint, paper, and plastics. There are several processes to form carbon black and they all rely on the thermal decomposition or the incomplete burning of hydrocarbons such as fuel oil or natural gas. “Furnace black” and “channel black” are produced most frequently.
Carbon black
Carbon black is produced by the partial oxidation or thermal decomposition of hydrocarbon gases or liquids. Several processes have evolved over the years, yielding a variety of products that differ in particle size, structure, purity and method of manufacture, including furnace black, thermal black, lampblack, acetylene black and channel black. Furnace black is by far the predominant form of carbon black in commerce, and accounts for over 95% of total world production of carbon black. Thermal black is far less important and only minor quantities of the other three blacks are used in highly specialized applications. Approximately 70% of the world consumption of carbon black is for the production of tyres and tyre products for automobiles and other vehicles. Approximately 20% is used in other rubber products such as hose, belting, mechanical and moulded goods, footwear and other uses, and the remainder (nearly 10%) is used in plastics, printing ink, paint, paper and miscellaneous applications.48
Production Processes
Carbon black was first produced many centuries ago for use as a pigment in inks and lacquers by a simple lampblack process. The channel black process was developed in the nineteenth century when large quantities of natural gas became available, but worldwide use of carbon black was still less than 1000 tonnes. Following the discovery of the usefulness of carbon black in the reinforcement of rubber at the beginning of the twentieth century, production increased rapidly and a gas-furnace process was introduced in the 1920s. In the 1940s, oil supplanted gas as a feedstock in the production of furnace black and, following the end of the Second World War, carbon black manufacture was established in many industrialized countries.49
Furnace black
The oil-furnace process generates > 95% of all carbon black produced in the world. It was developed in 1943 and rapidly displaced previous gas-based technologies because of its higher yields and the broader range of carbon blacks that could be produced. It also captures particulates effectively and has greatly reduced their release into the environment around carbon black plants. The oil-furnace process is based on the partial combustion of residual aromatic oils. Because residual oils are widely available and are easily transported, the process can be carried out with little geographical limitation, which has led to the construction of carbon black plants all over the world. Plants are typically located in areas of tyre and rubber goods manufacture. Because carbon black has a relatively low density, it is far less expensive to transport feedstock than to transport the carbon black.50
The basic process consists of atomizing preheated oil in a combustion gas stream that is formed by burning fuel in preheated air. Some of the atomized feedstock is combusted with excess oxidant in the combustion gas. Temperatures in the region of carbon black formation range from 1400 to > 1800 °C. The gases that contain carbon black are quenched by spraying water into the stream as it passes through a heat exchanger and into a bag filter. The bag filter separates the unagglomerated carbon black from the by-product tail gas, which comprises mainly nitrogen and water vapour. The fluffy black from the bag filter is mixed with water to form wet granules that are dried in a rotary dryer and bagged or pelleted.50
Preferred feed stocks for the oil-furnace process are heavy fuel oils such as catalytic cracker residue (after removal of residual catalyst), ethylene cracker residues and distilled heavy coal-tar fractions. Other specifications of importance are absence of solid materials, moderate-to-low sulphur content and low alkali metal content.50
Thermal black
Thermal black is made by the thermal decomposition of natural gas, coke-oven gas or liquid hydrocarbons in the absence of air or flames. Its economic production requires inexpensive natural gas. Today, it is among the most expensive of the carbon blacks that are regularly used in rubber goods. Because of its unique physical properties, it is used in some rubber and plastics applications such as O-rings and seals, hose, tyre inner liners, Vbelts, other mechanical goods and in cross-linked polyethylene for electrical cables.50
The thermal black process, which dates from 1922, is cyclic and uses two refractory lined cylindrical furnaces or generators. While one generator is heated to about 1300 °C with a burning mixture of air and hydrogen off-gas, the other pre-heated generator is fed with natural gas which ‘cracks’ to form carbon black and hydrogen. The effluent gas, which comprises approximately 90% hydrogen, carries the carbon black to a quench tower where water sprays lower its temperature before it enters the bag filter. The carbon black collected from the filters is screened, hammer-milled and then bagged or pelleted.50
CHAPTER THREE
MATERIALS AND METHOD
Materials
The materials which were employed in this work included;
- Carbon rodfrom used cell battery which was collected from around the community municipal waste disposal areas in Amaizu, Afikpo North Local Government Area, Ebonyi state;
- Coalobtained from Nigerian Coal Corporation, Enugu office;
- Spent automobile tyre (Dunlop) bought from dealers in Nsukka; and
- Furnace carbon blackobtained from a Construction Company, Ferotex Construction Company in Nsukka.
Apparatus
Unless otherwise stated, every apparati used for the work were gotten from the post-graduate chemistry laboratory, University of Nigeria, Nsukka. Among them are:
Electrical furnace from Civil Engineering Department, University of Nigeria, Nsukka
Manual domestic grinder procured from the market, Pestle and mortar
Electrical Sieve, Conical flasks
Electrical weighing balance,
Whattman filter papers,
Beakers, Stirring rod,
Nose mask and Eye goggle.
Electric oven, Reflux condenser
250ml 3-neck flask, Scrapper
Thermostat, Heating vessel,
Thermometer, Retort stand, Spatula
Digital viscometer (NDJ-5S) from National Centre for Energy Research and Development, University of Nigeria, Nsukka Enugu State.
Reagents and Chemicals
The chemicals used for this work were of analytical and industrial grades and were procured from reputable chemical shops in Nsukka and Enugu. The chemicals include;
CHAPTER FOUR
RESULTS AND DISCUSSION
Pictorial images of samples before and after preparation prior to ink production proper are shown below in the figures below (4.1- 4.8). Figures 4.2 and 4.3 are samples of coal and automobile tyre respectively after pyrolysis. Figure 4.5, (furnace carbon black) shows the pulverized form.
CHAPTER FIVE
Summary / Conclusion of Result
The production, optimization and application of offset printing (black) ink from waste carbon sources such as Furnace soot, spent Graphite rod, Coal and spent Tyre was successfully carried out. This research work has revealed that offset printing ink can be produced in Nigeria even from waste and locally accessed materials thereby converting waste to wealth.
This research also has shown that the produced ink quality: viscosity, printability, composition formula, and print-out material show a high degree of compliance with the imported inks even without certain special ink additives.
Re-use and management alternative for domestic and industrial waste has been identified through material recycling.
The focus towards being ‘green’ with environmentally-friendly products and practices have been adopted and sustained in ink technology even in this work. This work agreed with the push to zero VOC and formaldehyde-free options campaign. Other advantages that encourage the use of linseed oil and all vegetable oils include their relatively low viscosity-temperature variation; that is their high viscosity indices, which are about twice those of mineral oils. Additionally, they have low volatilities as manifested by their high flash points. Significantly, they are environmentally friendly: renewable, non toxic and biodegradable.
The work has also research provided a development background for production of home-made ink for the vast printing industries in Nigeria.
Therefore, further research works in this direction would do well to focus on investigation of other vegetable oils, as solvents and natural resins (apart from alkyd and colophony) available in Nigerian. Further studies to investigate the quality of print works by application of nano-particle (Nano-chemistry) of the black pigments would also be encouraged.
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