Industrial attachment report

1.0 INTRODUCTION

This report is a practical experience acquired by me in the course of my industrial training at Druckfarben Nigeria Limited (DFN) under the student industrial work experience scheme (SWIES).

In the earlier stage of science and technology education in Nigeria, students were from their respective institutions without any technical knowledge or working experience. It was in this view that students undergoing science and technology related courses were mandated in different institution in view of widening their horizons so as to enable them have technical knowledge or working experience before graduating from their various institutions.

The Student Industrial Work Experience Scheme (SIWES) was established by the Industrial Training Fund (ITF) in 1973 to enable students of tertiary institution have technical knowledge of industrial work base on their course of study before the completion of their program in their respective institutions. The scheme was designed to expose students to industrial environment and enable them develop occupational competencies so that they can readily contribute their quota to national economic and technological development after graduation. The major background behind the embankment of students in SIWES was to expose them to the industrial environment and enable them develop occupational competencies so that they can readily contribute their quota to national economic and technological development after graduation.

The major benefit accruing to students who participate conscientiously in Students Industrial Work Experience Scheme (SIWES) are the skills and competencies they acquire. The relevant production skills remain a part of the recipients of industrial training as life-long assets which cannot be taken away from them. This is because the knowledge and skills acquired through training are internalized and become relevant when required to perform jobs. The Objectives of this scheme includes;

• Exposure of participating student to industrial based skills necessary for a smooth transition from the classroom to the world of work
• It affords students of tertiary institutions the opportunity of being
  familiarized and exposed to the needed experience in handling equipment and machinery that may not be available in their institutions.
• Provide an avenue for students in higher institutions of learning to acquire industrial skills and experiences during their course of study.
• Provide an avenue for students to comprehend the theoretical aspect of what they encounter in school to real work situations, thereby bridging the gap between theory and practice.
• Enlist and strengthen employers’ involvement in the entire educational process and prepare students for employment in Industry and

Commerce. Participation in SIWES has become a necessary pre-condition for the award of diploma and degree certificates in specific discipline in most institution of higher learning in the country in accordance with the education policy of government. An industrial chemist needs a regular update of his knowledge and practice because of the ever expanding roles and complexities of the profession. Therefore SIWES is highly beneficial to the student chemist and it enables him to blend theory with the practical experience in all the functional areas of industrial chemistry.

CHAPTER TWO

2.0 HISTORY OF DRUCKFARBEN NIGERIA LIMITED

Druckfarben Nigeria limited was established in 2010 in collaboration with A.G. Leventis and they engage in premixing and production of flexography and rotogravure inks for flexible packaging in printing industries. It has subsidiaries in Romania, Bulgana, Serbia, Cyprus, Hellas and is listed in the Attens stock exchange. Druckfarben’s headquarters are located in Aspropyrgos and Attica. It has four production facilities, three in Greece and one in Romania. Currently, Druckfarbens business activities are conducted in over 20 countries as far as Russia, Ukrains, Nigeria and North Africa.

2.1 ORGANISATIONAL STRUCTURE OF DRUCKFARBEN NIGERIA LIMITED

The overall head of A. G. Leventis is the Managing Director and DFN Ltd as a group member of A. G. Leventis is headed by the General Manager who takes most of the important decisions in the company. The General Manager who is the head management committee and Financial Controller communicate with the Managing Director and management committee directly, who in turn is responsible to the other partners (Board of Controllers). Each section is headed by a manager who reports to the General Manager

Fig. 1.0 Organizational Structure of Druckfarben Nigeria ltd 2.2DEPARTMENTS IN THE ESTABLISHMENT
Druckfarben Nigeria ltd has four major department namely; production, security, marketing and commercial department. All the head of each department include the Factory Manager/Technical commercial manager, Marketing Director, Chief Security and the Financial Controller respectively. All are directly responsive to the General Manager.

PRODUCTION

The head of this department is the Production Manager. As the Production Manager, he must ensure quality of produced ink, formulations, laboratory research work, files and statistics, production program, productivity and capacity, laboratory and production floor housekeeping safety and maintenance. Under him are the Technical commercial manager, senior production manager, truck driver and quality assurance manager. The Technical commercial manager visits customers regularly on new orders, new products, technical problems, trouble shooting, technical reports to the laboratory, payments control, reports on competition moves, guidance on the use of products, design, propose products on new demands and technical proposals e.g.( mixing station, press returns utilization).

The truck driver distributes goods to customers and functions on these areas; loading goods to the truck, checking on loaded quantities, unloading goods from the truck, truck maintenance and ensures that the products get to customers. The Quality Assurance/Assistant Laboratory Coordinator takes care of the laboratory and ensuring that various tests and analysis are properly carried out. The Quality Assurance/Assistant Laboratory Coordinator is also the Product Inspector. The Senior Production Manager takes care of production processes with the forklift driver who transports needed materials for production from the warehouse to the work floor and the production workers produce colour shades of ink according to formulations from the laboratory and production program, ensure tidy work floor, clean equipment after use, package and load the goods.

FINANCE (accounts)

This department is headed by the Financial Controller and takes care of the company’s finance. He keeps the company’s accounts that involve statement of money received and spent. This department provides the information for the company to attract investors, establish lines of credit and plan for the future. They also pay workers’ salary.

Assisting him are the Accountants, Account Clerks and the Store Keeper who does inventory at the end of every week keeping record of used raw materials during the week. The coordinator is the Administration (head of personnel), he oversees the welfare of the workers and he is involved in employee’s recruitment exercise and he oversees the importation of raw materials.

PRODUCTION MARKETING

Druckfarben Nigeria limited has a very good organized marketing scheme. The General Marketing Manager is directing it, with marketing professionalism. The marketing manager reports to the General Manager on day to day sales activities and gives the plan on how to keep improving the sales target or goal of the company such as commercial offers to customer on updating, reforming offers, creating and renewing contracts with customers, market reports and news trend, monthly updated market report, sales monitoring and sales growth. The company also has a well design communication network to ensure that every necessary connection is in place for smooth transaction on daily basis.

SECURITY

The head of this department is the Chief Security Officer who supervises other gatemen. This department ensures the company’s safety from internal and external saboteurs. The security men see to the movement of employees, people and goods in and out of the premises.

2.4 MAJOR PRODUCTS OF THE ESTABLISHMENT

• Water based inks (20kg in plastic buckets and 200kg in container drums upon request).
• Solvent based inks (20kg in metallized pails and 200kg in container
  drums upon request).

CHAPTER THREE

2.0 NATURE OF WORK, SKILLS AND EXPERIENCE GAINED ON THE COURSE OF THIS SCHEME

I was attached in the production department, laboratory section.
Precautions taken in production floor:

• Use of cell phones is restricted.
• Smoking and naked fire is prohibited.
• Ensure working environment is well kept
• Do not eat or chew in the working environment.
• Wash hands with ethyl acetate or water and then with industrial soap, rinse with water. •Put on your safety kits (white wears, safety booth, nose pad, eye goggles and hand glove).

3.1 RAW MATERIAL USED IN THE INDUSTRY

The raw materials for ink production are pigments, resins, solvents and additives. They are semi-finished products.

Pigments

Pigments are considered to be the chief constituent of ink and contribute about 50 per cent of its cost. A pigment is essentially any particulate solid, coloured, black, white or fluorescent that alters the appearance of an object by the selective absorption and/or scattering of light. It occurs as a colloidal suspension in ink and retains a crystal or particulate structure throughout the colouring or printing process. Pigments colour the ink and provide gloss, abrasiveness and resistance to light, heat, solvents, etc. Pigment used can be classified into organic or inorganic pigments.

Colour Index System (CIS) number is generally used to identify organic pigments in modern inks. It reflects the colour shade or hue, chemical structure and chronological details (order of synthesis) of the pigment. Organic pigments are polycyclic pigment (Phthalocyanine Blue PB 15.4, phthalocyanine Green PG7), azo pigments (shades of yellow PY 74, PY13), β naphthol pigments (shades of red PR48.1, PR48.2, PR53.1, PR57.1, PO34) and black pigments (P.BL7) consisting of Carbon Black.

Inorganic pigments are white pigments (mainly titanium dioxide PW6) which are opaque or transparent pigments and Colour pigments (metallic effect pigment (gold and silver bronzes), pearlescent pigment, fluorescent pigment) which are been produced from either mineral sources (the inorganic colour pigments) or from organic derivatives of coal tar (the organic color pigments).

Varnishes:

Varnishes are primarily resins/binders that bind the other ingredients of ink together so that it forms a film; they also bind the ink to the substrate applied. The type of varnish to be used in a particular ink is dependent upon the type of drying system utilized. Inks that dry via oxidation and/or polymerization require drying oil varnishes and paper qualities that do not allow the varnish to be drained away before oxidation can take place. Inks that dry via evaporation utilize low-boiling-point solvent-resin varnish. Inks that dry by absorption utilize non-drying oil varnishes that do not dry by other means before they can be absorbed into the paper.

Inks that use a combination of drying mechanisms, such as quick-set inks, have a portion of the varnish—a solvent—absorbed first into the paper, and a resin-oil mixture left behind which dries by oxidation and polymerization. Quick-set inks use a resin-oil varnish. They also contribute gloss, resistance to heat, chemicals and water. More than one resin is typically used in an ink formulation. Common resins used in ink formulations Acrylics, Ketones, Epoxides, Alkyds, Polyamides, Cellulose derivatives, Formaldehydes, Hydrocarbons, Rubber resins, Isocyanate, free polyurethanes etc. Solvents

These are used to keep the ink in liquid form from the period when it is applied to the printing plate or cylinder until when it has been transferred to the surface to be printed. At this point the solvent separates from the ink to allow the image to dry by different drying processes depending on the type of ink and bind to the surface.

The main criteria by which to choose solvents are solutions and drying capabilities. Most flexography or rotogravure inks contain mostly ethyl alcohol and or ethyl acetate. Poly vinyl chloride based printing inks for instance contain almost exclusively ethyl acetate because their binders would not dissolve in ethyl alcohol. Such solely ester based inks are limited to gravure printing because high ester content will corrode the flexography plates. Printing processes such as gravure and flexographic require a solvent that evaporates rapidly. These use volatile solvents (i.e. those with boiling points below 120°C) such as ethyl acetate, ethanol, methoxyl propanol etc. Additives and Catalysts:

Reducing oils and solvents such as thinner can be added to increase the ink’s setting capacity. Antioxidants and anti-skinning agents can be added to keep ink from oxidizing and settling while it is still on the press. Corn starch is added for body and to reduce ink setoff, while surface active agents are used to enhance the dispersion of pigments in the vehicle. Additives are used to alter the final properties of the formulation. These include:

• (i). Plasticizers which enhance the flexibility of the printed film; e.g., di butyl phthalate
• (ii).Wax which promotes rubs resistance in solvent based inks. E.g. Carnauba-an exudate from the leaves of Copernicia prunifera consisting of esters of hydroxylated unsaturated fatty acids with at least twelve carbon atoms in the acid chain
• (iii). Drier which catalyzes the oxidation reaction of inks that dry by oxidation; e.g., Salts or soaps of cobalt, manganese or zirconium
• (iv). The Bodying agents which increase the viscosity of an ink
• (v).Antioxidant which delays the onset of oxidation polymerization by reacting with free radicals formed during the auto oxidation thus preventing them from reacting further; e.g., eugenol
• (vi).Surfactants improve the wetting of either the pigment or substrate. They act as stabilizing agents for pigment dispersion
• (vii).Alkali which controls the viscosity/solubility of acrylic resins in water based inks e.g. Mono ethanolamine
• (viii)Defoamer which reduces the surface tension in water based inks so that stable bubbles cannot exist; e.g. hydrocarbon emulsion

3.2 RAW MATERIAL CONTROL

Raw materials are carefully selected to ensure that the components of the packaging inks comply with the requirements of appropriate national legislation and are suitable for quality and are within agreed tolerances. The following are considered: Suitability

Raw materials are selected in line with packaging materials so that, when packaging, inks are correctly applied, the printed surface should not:

• endanger human health.
• deteriorate the organoleptic nature of the packed substance.
• bring about an unacceptable change in the composition or quality of the packed substance. Identification

Products code name, reference number and batch number are used to identify each raw material, so it can be traced. Specifications
Each raw material has a specification agreed between the customer and the packaging ink manufacturer. The specification includes physical and chemical properties to maintain agreed ink manufacturing quality and print end-use technical requirements. Conformity

Where appropriate raw materials are tested in house or alternatively are supported by a certificate of analysis from Druckfarben Hellas, relating to the agreed specification of customer. In some instances, pre delivery samples representing the batch may be submitted to the customer for special tests prior to the delivery being accepted. Storage

Raw materials have shelf life of 12 months and are stored in a dry well ventilated place, where the temperature will be controlled (5–25 °C). The containers should be tightly sealed to prevent contamination or deterioration.

Usage

Rotates raw material inventory on a “first expired – first out” basis. Raw materials are Re-tested based upon their shelf-life requirements to determine suitability for continued use.

3.3 PRODUCTION OF INK

The formulation, equipment and production process are recipes for the production of ink. These processes are consecutively performed on individual products. There are two main types of ink namely;

1. Sovent base ink
2. Water base ink

The difference between these two ink is the use of water as a solvent when producing water base ink while other solvents such as; ethanol, ethyl acetate etc. is been used in the production of solvent based ink. Printing inks are made of four basic components:

• Pigments – colour the ink and make it opaque
• Resins – Binds the ink together into a film and bind it to the printed surface
• Solvents- makes the ink flow so that it can be transferred to the printing surface
• Additives – which alter the physical properties of the ink to suit different situations

Pigments Additives Resins Solvents
The production processes comprise the following

1. Varnish production
2. Base production(pigment dispersion)
3. Ink production
4. Filtering and packaging

Step1- Varnish Production

Varnish is a clear liquid that solidifies as a thin film. It binds the pigment to the printed surface, provides the printability of the ink and wets the pigments particles. There are two main sorts of varnish: oleo resinous varnish which incorporates a drying oil such as linseed oil and non- oleo resinous varnish.

Oleo resinous varnish is a manufactured at much higher temperatures and in much rigorous conditions than non- oleo resinous varnish. These varnishes are manufactured through the same process.

Different varnishes are made for different inks, Varnish are produce by dispersion of powders and/or flakes and resin solution into a solvent mixture. The resins react together to some extent to make larger molecules, making the varnish more viscous the longer these reactions are allowed to occur.

Oleo resinous varnish production

These varnishes are typically manufactured in closed kettles where the oil and solvent are heated to allow for rapid solutioning or trans esterification. The temperatures involved in the process will vary but may range from 120°C to 260°C. Cooking times may range from a few minutes to several hours. Temperature control is critical in the process. Rate of temperature change, maximum temperature attained and cooking duration is closely monitored. A condenser is usually used to prevent solvent loss.

Since these varnishes include a drying oil, atmospheric oxygen must be excluded to prevent this from polymerizing. For this reason cooks are often done using a nitrogen blanket. In the production of a typical oleo resinous ink varnish, drying oil, alkyd and other solvents are added to the vessel under nitrogen prior to cooking. Hard resins are then added when the correct temperature is attained. The cooking process continues until the reactants are either totally consumed in the trans esterification process or achieve adequate solubility in the solvent. Additives such as the chelating agent are added after the batch cools down. Finally, the varnish mixture is reheated to obtain targeted rheological9 properties. The varnish produced is tested before sending to the storage tank.

Non-oleoresinous varnish production

Varnishes of this type are usually simple resin solutions that do not require high temperatures to effect a reaction. They are manufactured by breaking up the resin particles and dissolving them in a solvent in either a cavitation or a rotor / stator mixer. Cavitation mixers contain a saw tooth disc on a drive shaft and are used to produce high viscosity resin solutions. They can operate at variable speeds. Rotor / stator mixers operate at a fixed speed. Varnishes produced in these mixers must be of lower viscosity than those produced in cavitation mixers because the agitation in the mixer is much less. Heat sensitive resins cannot be used in a rotor / stator mixer because the high friction within the mixer produces high temperatures.

Step 2- Base Production

This is the dispersion of pigments into varnishes. High speed / controlled
shear mixers is used in the blending of pigment and varnishes. Then bead mill in other to remove agglomerate. The pigment is then coated with resin to prevent re-agglomeration and flocculation. There are three main types of equipment used for this production, and which is chosen depends on the tack (stickiness) and rheology of the ink. The three equipment types are discussed below.

Three roll mills

A three roll mill consists of a series of cambered rollers rotating in opposite directions. The pigment particles are fed into a hopper above the two rear-most rollers and are dispersed by the shear forces between the rollers. A doctor blade is fitted to the front roller to remove the dispersed product. Roll pressure, speed ratios and temperature must be carefully controlled to allow reproducible dispersion. Each of the rolls is water cooled to reduce the buildup of frictional heat.

Bead Mills

A bead mill consists of a cylindrical chamber filled with beads and surrounded by a water jacket for cooling. Ink is pumped into the chamber and the beads (known as the ‘charge’) set in motion by a series of spinning discs or pins. The charge grinds the ink, breaking up the pigment clumps and evenly dispersing the ink. The ink then flows out of the chamber through a sieve and the charge remains behind to be re-used. The bead size depends on the viscosity and rheology of the ink.

Typical bead sizes range from 1-2 mm for a high quality low viscosity product such as a gravure ink up to 4 mm for a medium viscosity paste or screen ink. The beads can be made of zirconium oxide, glass or stainless steel. Certain beads discolour certain inks, so it is important that each ink is tested with the different beads before grinding to ensure that appropriate beads are used.

Step 3- Ink Production

Ink is produce by blending of bases and varnishes using a high speed controlled shear mixers. Then add alcohol e.g ethyl acetate, ethanol etc, followed by wax. After that, stir thoroughly with high speed shear mixer.

Note: Addition of alcohol is dependent on the type of machine been used for the printing. For instance, ethyl acetate which is a fast drier is been used to produced inks that are meant for fast drying machines and vice versa.

The ink must possess homogeneity, no-flocculation, pigment stability (not shocking effect), temperature control, predictable viscosity, minimum solvent medium loss. The ink must be a stable colloid of inert materials suspension in a continuous phase.

Step 4- Filtering and Packaging

This is the final stage in the production of printing ink and involves the filtering of the produced ink to remove agglomerates (seedling) and contaminants for smoother and more consistent printing without drag lines and scrumming and packaging in containers of different sizes.

3.4 FORMULATION OF PRINTING INKS

The following parameters are considered when formulating printing inks:

• End-user specifications
• Type of foodstuffs to be packed
• Package-forming and filling processes
• Type of substrate and material combinations
• Type of printing processes and printing equipment
• Compliance to health, safety and consumer protection regulations
• Compliance with environmental policies for printing, manufacturing processes and end-use.

When formulated Printing inks are appropriately applied:

• They will have no visible transfer on the reverse side of printed matter.
• They will allow compliance of the final product with the existing legal provisions
• They will cause no deterioration of the organoleptic nature of the packed substance.
• They are suitable for the method of application and for subsequent converting processes
• They have the necessary adhesion of the dry layer to the substrate and resistance to physical and chemical stress
• They have the binder/colourant combination which will meet product resistance specifications such as ISO standards or other agreed end use specifications,
• They will both minimize potential migration through the substrate or the set-off from the printed outer side to the food contact surface in the stack or the reel.

CHAPTER FOUR

4.0 EQUIPMENTS USED FOR MIXING AND PROCESSING

In mixing of any products, weighing of raw material determines the volume of production. The recipe for each product depending on customer’s specification is formulated by laboratory manager and quantity of raw material to be weighed is calculated by the Production Manager, who then collects the raw materials from the store, weighs accordingly using the weighing balance. The weighed ingredients are mixed.

In processing, some equipment used is as follows:

Tanks

Tanks can generally been divided into these categories according to its function:

Mixing tanks

These tanks are mainly used as mixing container for mixing different batch production products and for the mixture of ingredients needed for the production. The tanks usually have a single stainless steel shell. Equipment for temperature control may be fixed. Imported stainless steel material ensures the good appearance of welded joint. Inside and outside is polished and easy to clean. The bottom is with slight slop to empty materials completely. The bottom has outlet to facilitate materials discharging with cover to avoid material splashing during mixing and volatilization of the solvent materials.

According to mixing requirements, tank can be designed with rounded bottom angle to avoid dead corner during mixing process. According to production requirements, tank can be equipped with brake wheels (remove or fix easily) or with forklift channel (Removing or lifting the tank to discharge materials to reduce the working intensity, which is of great help for plant production management)

Storage Tanks

Storage Tank is used for the storage of raw materials. They store liquids of organic compounds and solvent. The tank is made of plastic and has a metal jacket which is earthed to prevent fire explosion due to solvent based raw materials stored. The selection of storage is according to the materials property and according to the requirements of the production technology; jacket is earthed and agitator mechanism is optional.

Mixing Tanks

Storage Tanks

Mixers

The mixer is mounted on a hydraulic lift which can be raised or lowered. This is to either withdraw the mixing blade from a tank or to place the high speed mixing impeller at the most desirable level in order to achieve the best flow pattern. Agitators are rotating in fixed direction. During the rotating process, the agitators drive the materials to rotate in axial and radial direction resulting in material axial motion and circular motion in the container at the same time. So the materials, under action of shearing mixing and diffusion mixing as well as other mixing effect at same time are dispersed and mixed efficiently. It is mainly used for mixing liquid-liquid, solid-liquid and other combination.

Mixer

Milling Machine

The principle of milling ink slurry (the combination of pigment material and the vehicle) involves exposing the mixture to a greater shearing and mixing force that can be produced in the mixing stage. A typical milling machine is the Bead Mill. It principally consists of beads filled cylindrical chamber. This device expose the ink slurry to a shearing force by spinning the slurry in a cylinder containing balls pumping the slurry through a rotor-stator arrangement. The size of the beads depends upon the viscosity and rheology of the final product, i.e., the type of ink required. For high quality low viscosity ink, e.g., gravure, typical bead size may range from 1-2 mm; for medium viscosity paste ink the bead size may range up to 4 mm. These beads are usually made of zirconium oxide, glass or stainless steel. A drawback usually faced by the manufacturer during this operation is that certain beads may cause discolouration of ink; thus, it is very important to test a particular type of ink with different beads before grinding for the selection of appropriate type of bead-ink combination.

In this type of dispersal operation, ink has to be pumped into the chamber and the beads (charge) are set in motion by a series of spinning discs or pins. The beads in motion break up or grind the pigment clumps and provide even dispersal of ink. The dispersed ink is then sieved out of the chamber; the beads remain behind and may be reused. It is also used in dispersing of pigments to ensure pigment particles do not clump together.

4.1 CLEANING OF THE EQUIPMENT

Waste gas treatment in commercial printing is essential to remove dust, aerosols, and volatile Compound. Cleaning processes of particular importance to the printing industry include physical adsorption to solid materials, thermal after-burning, catalytic conversion, and bioactive filters or scrubbers. If used successfully, environmental controls may reduce VOC’s by more than 90%and nearly eliminate particulate matter from escaping. Dust removal devices include cyclones, wet dust scrubbers, filters, and electrical precipitators. Vapour removing devices include condensation, absorption, adsorption, thermal treatment (“after-burning”), catalytic conversion and bioactive scrubbers and filters. While these technologies are appealing, the costs associated with emissions control often place the latest technologies out of reach for the average printer

4.2 PHYSICOCHEMICAL LABORATORY

In the physicochemical laboratory, analysis is done on raw materials, semi-finished and finished products undergoing production processes but before analysis is carried out, customer specification for products such as color for inks has to be formulated by color mixing and color matching with customer’s standard color in the working area.

Basically the laboratory working environment consists of two parts:

• a.Workplace with PC and software
  b.Workplace with inks, proof-printer, balance and possibility to get water The lab is equipped with air-condition and a good ventilation when using solvents.

Equipment/Working environment

a. PC-workplace:

• Enough power outlets
• Locker with lockable doors for keeping software, documents, etc. •PC with formulation software, internet access and network interface card
• Light box with switchable light sources and elevated positioning for better visual appraisal (important for detecting metameric effects)
• Measurement subsurface of neutral white colour and large enough for adequate measurements (e.g. ceramic block tile in the center, with a smooth, glass covered, neutral white tile surface with size of about 40×40 cm)

b. Color-mixing workplace:

• Wash stand
• Detergents
• Rack for basic inks, extender, etc.
• Circuit rail with at least. 5 power outlets
• Highly absorbent cleaning tissues and rags
• Plastic pipettes with two different volumes
• Proof-Printer and coaters (k bars) for drawdowns
• Robust floor unit construction with sufficient storage space • Plastic cups of about 150ml to 200ml for mixing lab calculations • 500ml to 1000ml PET-containers used for storing sample inks, extender etc.
• Analytical balance (0.01g) for weighing smallest amounts of calculated recipes
  Spatulas for manual mixing and laboratory mixer for mixing samples to avoid thixotropic phenomenon

There are three basic stages to color mixing. these includes; colour mixing, colour matching, and colour testing in the laboratory a.Colour Mixing

The mixing of inks to match a particular color for printing is done in the laboratory. The important factor in color mixing is identifying in which particular color direction a base ink has to go to match the desired color. For example, yellow ink can range from a greenish yellow to an orange green, blue can range from purple to green brown, commonly a dark orange can either be reddish or yellowish, purple can range from red to blue etc.

It is also important for the ink mixer to keep on hand a sample of the mixed ink (in case more is needed), a detailed record of the formulation and a press proof, an example of how the color prints on the intended substrate. Another important consideration in color mixing is to ensure that all the ingredients added are chemically and mechanically compatible. Inks that dry by evaporation should not be mixed with inks that dry by oxidation and so forth. Some mixtures can also possess a lesser degree of permanence than the constituent inks; a problem not typically noticed until after the material is printed. For example, some types of yellow pigment will react with iron blue, causing the desired shade of green to become increasingly darker.

b.Colour Matching

In matching a color, the key or base color will form the primary component of the ink mix. A small test sample should be mixed, and a dab of the final ink placed on the intended substrate, to ensure that the ink will retain its color after printing and drying. The ink can also be drawn down on other substrates for detailed comparison. Careful measurements should be made throughout the test sample mixing, to ensure that when the time comes to make the final batch, the proportions of the mixed colors will produce the same result. By utilizing color charts, the three color measurements—hue (the specific wavelength or shade of the color), value (its degree of darkness or lightness), and Chroma (its strength)—can be determined and each of these three color aspects can be adjusted by the color mixer.

The hue can be adjusted by adding the color that will bring it back in the direction it needs to go. If a blue is too purple, yellow or green may need to be added. If the value is incorrect, the ink will need to be darkened or lightened, using either black (which has the tendency to dirty an ink, however) or a suitable dark color, or white or suitable light color. If the Chroma is incorrect, adding neutral gray can help bring the color purity where it needs to go. Should too much gray be added, the original base color can be
added to reverse the graying trend. c.Colour testing

Testing of the ink should check three aspects: accurate color, correct drying, and run ability congruent with the printing method to be used, the press speed at which it is to run, the substrate on which it is to be printed, and the desired end-use characteristics of the printed material. Testing can be accomplished by depositing a sample of the mixed ink on a sample of the actual stock to be used (inks will behave differently on different types of paper or other surfaces), either by dabbing a small bit of the ink on the substrate in a thickness approximating the intended thickness of the printed ink film (called drawdown), or on a proof-press of the intended printing process. Proper ink drying is commonly evaluated after an appropriate length of time and the dried ink is examined for gloss, opacity, and color. Analysis carried out includes;

TOTAL SOLIDS (% DRY SOLIDS)

Procedure

-A glass made petri disc is placed on a laboratory balance (2digit accuracy) and tare to get a zero indication. -2-3g (B) of the liquid ink is measured on the glass disc. -The reading of the glass disc together with the ink quantity is taken as (A).

– Glass disc is being placed inside a laboratory ex-proof oven at a temperature of Ts-80◦ C for 12hrs.

-After 12hrs period, the glass disc (which has a solid now residue) is taken out from the oven and left to cool down at environment temperature for about 5minutes.

-The reading is taken on the laboratory balance as (C).

Calculation

The % total solids of the sample to be tested are calculated by: A – C =D
% dry solids = {(B – D)/B} x100

VISCOSITY

It is the measurement of flow of the resistance of fluids. This experiment is carried out on varnishes and ink products. Zahn cup or ford cup is the instrument used. Depending on the product required there are different numbers of the cup that can be used. Procedure

-Dip the cup into the product.
-Start the chronometer as the cup is lifted out and the top of the cup breaks the surface -Take the reading of the viscosity
-Stop the chronometer at the first definite break flow of the fluid
Diagram showing the process of measurement of viscosity

DILUTION

This is diluting ink at running viscosity with a required solvent depending on the type printing machine. Zahn cup or ford cup is the instrument used. Procedure

-A certain quantity of the sample ink is weighed in a laboratory balance -The sample is stirred manually or in a lab mixer to eliminate any risk for thixotropic phenomenon, etc. -Afterward it is cooled to a temperature of 20◦ C

-In sequence solvent is added (or water if it is about water based inks) with viscosity reading taken at each interval in order to dilute it at the printing viscosity. -The viscosity is being measured according to Viscosity measurement -The selection of solvent to dilute the sample to be tested is depending on the series of the ink. As printing viscosity, usually it is considered to be: NB:Flexography inks 25 sec Zahn cup 2

Rotogravure inks 20 sec Zahn cup 2
or if it is differently defined.

The result of the measurement is being expressed as a % percentage of solvent that has been added to the sample, in order to have it diluted at the printing viscosity level.

NB: basic solvent for dilution per ink category

• Rotogravure inks -Ethyl acetate (EAc)
• Flexography inks (n/c based) – Ethanol (Etoh)
• Vinylic inks -ethyl acetate (EAc)
• Water based inks -water (H2o)
• Or differently, mixtures of solvents could be used upon specific definition

DRYING TIME

• A sample ink is stirred in a lab mixer in order to eliminate any risk for thixotropic phenomenon, etc. -Afterwards it is been cooled at a temperature of 20°C
• Drawdown of the ink is printed on a treated side of precut white polyethylene film (alone or with standard sample in a side by side draw down comparison), using printing bar 2(K-bar 2 -red colour bar). -At the same time we set the chronometer ready.

-Immediately, by using another precut size of unprinted white polyethylene film (the treated side facing towards our draw down) start pressing manually in stages along on the printed draw down sample surface and by lifting periodically to observe transfer of ink from the printed surface to the unprinted PE surface. -The moment there is no more ink transfer (ink dry), we stop the chronometer. -The results of drying time are being expressed in seconds. Note: This particular test is indicative and does not represent 100% the procedure of ink drying during real printing operation on a machine. The measurement must be done under controlled conditions (room temperature 18-25◦ C) on air draft. Also, another substrate can be used upon specification.

TRANSPARENCY- VISUAL CHECK

• The sample that is to be checked is stirred in a lab mixer/shaker in order to eliminate any risk for thixotropic phenomenon, etc.
• Afterwards it is been cooled at a temperature of 20°C
• The sample is being printed as pure ink (not diluted) alone or as standard sample for comparison on substrate leneta paper using printing bar number 2 (red colour) -k bar 2 in sequence, we make visual check (in comparison) transparency or opacity) looking at the black area of the Leneta paper.

The evaluation of transparency is being expressed on a scale from 1-5 following:

• (i)Very bad transparency
• (ii)Bad transparency
• (iii)Medium transparency
• (iv)Very good transparency
• (v)Excellent Transparency

Provided a special demand, this test could be made using a transparent substrate (e.g. Bopp) or and by using a diluted ink (by an approved in terms of humidity content, solvent

GLOSS- VISUAL CHECK
-The sample is stirred manually or in a lab mixer in order to eliminate thixotropic phenomenon -It is been cooled to a temperature of 20°C
-The sample is printed (as pure or diluted or by mixing with varnish 50:50) alone or comparison with standard sample on a leneta paper substrate by using a bar for printing (k-bar 2(red) or k-bar 1(yellow)). -The printed sample is left to completely dry

-The visual check of gloss is viewed on white area of leneta substrate. -The evaluation of gloss is being done on a scale 1-5 as follows:

• (i)Very bad gloss
• (ii)Bad gloss
• (iii)Medium gloss
• (iv)Very good gloss
• (v)Excellent gloss

Note: This test could be made using a transparent substrate (e.g. Bopp) or and by using a diluted ink.

PH VALUE

PH value is the index of acidity or alkalinity of an aqueous suspension which yields information which is about physical, chemical and technical properties. Instrument used is PH meter. Procedure
-A suspension is prepared from 4.0g pigment and 32ml distilled water with 4ml ethanol as wetting agent. -The mixture is shaken for one minute and then allowed to stand for five. -The PH value of the suspension is then measured with a glass electrode HEAT RESISTANCE

This is the ability of a material to withstand heat.
Procedure

• 50 mm x 20 mm specimen prints are heated in a drying oven
• The temperature of which is increased insteps of 10 °C (18 °F) at intervals of five minutes. The heat stability is the temperature at which the first change in color (when compared against a blank) becomes visible.

LIGHTFASTNESS

The lightfast properties of printing inks can be defined as the amount of resistance to fade or color change of a printed surface when exposed to daylight (or an artificial light source) over a set period of time. GLOSS

-The sample is stirred in a lab mixer in order to eliminate any thixotropic phenomenon. -The sample is measured and cooled to a temperature 20°C (Or any other temp btw 20-25°C) -The sample to be tested is printed (pure or diluted or in mixture with varnish 50: 50) alone or in comparison with standard sample on a leneta substrate by using a K bar 2 (red) or K bar 1 (yellow) printing bar. -The measurement is being done on the “gloss meter” device at 60° angle. -The result has no unit (pure number), as higher the result (number) the higher gloss is. ADHESION TAPE TEST

Simple evaluation as to whether ink has adhesion to substrate

CHAPTER FIVE

CONCLUSION AND RECOMMENDATION

5.0PROBLEMS ENCOUNTERED

During the course of experience, the major problems encountered include: HEALTH HAZARED
Laboratory analysts who work in the laboratory are faced with great health issues of chemical fumes. The laboratory can be a dangerous place for Laboratory workers sensitive to chemical fumes or vapours. According to research, experimentation processes can cause chemicals such as formaldehyde to become airborne irritants, ethyl acetate can cause irritation to the eyes and nose, throat and repeated contact on skin can cause drying and cracking, also, long exposure can affect the liver and kidneys and exposure to high levels can cause dizziness, slight headache and passing out to those working in the laboratory. These airborne toxins may also cause asthma attacks. Proffered Solution

It was suggested that Laboratory workers who are exposed to chemical fumes and vapours may be more comfortable with the addition of a corrosion resistant fume extractor fan present in the laboratory. A corrosion resistant fume extractor is designed to clean the air inside the laboratory and remove any fumes or odour present in the laboratory. A fume fan can intake the air and extract it out of the room leaving only the clean and smelling air inside the laboratory. There are many sizes, powers and types of fume fans for different laboratory situations and this depends on the size of the laboratory and what airborne chemicals will need to be removed from the air before purchasing a fume fan. FATAL INJURIES

Production worker are involves large portion of work force, and because of this, production equipments can also bring about involuntary accidents for the production workers by contacts with objects and equipment (e.g struck by an objects or caught in a machinery or materials), exposure to harmful substance and electrocutions from contact with electrical wiring, overhead power lines or electrically powered machinery or hand tools. These mentioned type of events account for nearly all fatal injuries among production workers. proffered solutions

Hazards are identified, analysed and controlled. The entire work site is inspected on a regular basis and results are recorded. Equipment is inspected to ensure its safe for operation and production workers are made to always put on their safety materials. FILING SYSTEM IN THE LABORATORY

Also, the Filing System of printed draw down is a problem as printed down downs are not properly filed and can be of great concern when technical issues arises. Proffered solution
Filing system was implemented so as to file printed samples according to customer 5.1EXPERIENCE
The SIWES program has helped me to acquire wide knowledge in colour chemistry both industrially and environmental, mostly in the following areas: (i). Conduct series of test using various methods.

(ii). Proper handling of some of the sophisticated laboratory equipment (iii). I also acquired managerial and administrative knowledge, which has helped in achieving the following: -Ability to work on the experiment and project with little or no supervision – Ability to work with my supervisors and other co-workers. – Ability to apply experience gained during the training in my final year project

5.2RECOMMENDATION
In order to assist the ITF in achieving IOS objectives, the following points are strongly recommended. ●Devising a new strategy that would ensure training new skills and modern techniques in conformity challenges at hand. ●Increasing the number of area offices and should be evenly spread across the country. ● Effectively bearing a proportion of the direct cost of on-the-job and off-the- job training of the trainees by continuously reviewing the allowances in proportion with economic reality that obtains at that time. 5.3CONCLUSION

I appreciate the management of Industrial Training Fund for organizing the SIWES program which has given me the great opportunity acquainting myself with practical experience in the Organization (Druckfarben Ltd). Graduates in Nigerian universities are often criticized by employers for lacking practical orientations, skills and competencies even though they are considered to be academically equal to their counterparts in other parts of the world to the theoretical grounding in the particular subject area. The lack of possession of relevant production skills by SET graduates is a manifestation of the over-emphasis placed on the educational component to the detriment of the training component in the formation of SET graduates. This report therefore focused on the complementary role of training in the formation of competent and productive technical manpower for the economy and national development. Specifically, the report appraised the effectiveness of the Student Industrial Work-Experience Scheme (SIWES) in the formation of technical manpower in general and in the professional development of an industrial chemist. Finally, this report specifically accounts for ink production and its uses in the manufacturing and printing industries.