“Develop success from failures. Discouragement and failure are two of the surest stepping stones to success.”
Engineering Sciences for Packaging
UNIT-1
Metals for Plate-making, Printing & Packaging:
Type metal: type metal is an alloy which is used in traditional type-founding and hot-metal typesetting. An alloy used for casting of type and spacing material is called a ‘type alloy’. Initially stage when Johannes Gutenberg manufacture of movable type was consists of lead, tin and bismuth. The bismuth has high melting point and expansion after cooled. After that, enhance quality of metal type, bismuth replaced by antimony. The metal in different proportion depending on the application (manual casting (movable type/foundry type), mechanical casting and stereo plates. Antimony and tin are added to lead for durability and reducing the expansion of the matrix when cooled.
Foundry metal: the foundry metal type has extra strength and harness made by grade 20% tin, 30%antimony and 50% lead. In the case, mono and lino type metal should not be mixed because it will clog to casting aperture of the lino and mono casting machine which work at a lower temperature.
Foundry type/ hot type: the word ‘type’ has been derived from the Greek word “typos” which means impression. A types is a three dimensional rectangular piece of metal or wood having a two dimensional printing image on its upper surface. Foundry type complete vanished from printing industry today.
Type dimension: as its name three dimensional, it’s has three dimensional length (body), width and height.
a. Body: the distance between front to Back of a type is called body (length). It is measured by point size system, and also known ‘body size’ and ‘type size’. The different varies in types of different sizes.
b. The width: the distance between Right to Left of a type is called width (set size). The width of a type is determined by its thickness. Thickness is depend on character, like the capital W, M, Z is wider than lowercase l, I, j, so there are increase the width of each character on a metallic type has little extra space on both side to allow the character to combine pleasingly when printed together in the form of words. Also depend on various type design like condensed and expanded. The width of a type is measured by ‘unit’.
a. Type height: the distance between Top to Bottom of a type is called type height. There are need to be uniform and accurate type height of all type to make uniform quality printing. The standard type height in India, Australia, Canada, U.K, Italy and U.S.A is 0.918” while in Egypt, France, Germany, Spain, Turkey and Switzerland it is 0.928”.
Physical structure of type: a structure of type has many no. of part which has very important on own basis.
a. Face: it is the topmost layer of the type which is reflected on the page of paper after printed. It is real identification of the type, we can identify through its face.
b. Serif: it is small stroke in any shape (line, arc and bracket) which used at the top and bottom of the various main stroke of a character.
c. Head: it is the top of the back side of the shank. Shank is the main rectangular body of the type which support the face and start from shoulder to feet.
d. Bevel: it is the slope from the bottom face edge line to the shoulder of the type.
e. Shoulder: it is the flat area of the top of the shank on the belly side (front of rectangular) the type. It start form where the bevel ends.
f. Beard: it is the taken both part (bevel and shoulder) together. It is from the bottom line (bevel) to flat portion shoulder (top of the shank) of the type.
g. Counter: it is the open lines or enclosed (if fully rounded area of counter are called ‘bowels and the elliptical bowels are known as ‘loops’) area of a type and is slightly higher than the shoulder.
h. Pin mark: it is mark which are found on only foundry made type in shape (circle or triangle) cavity on the right side of the type carry manufacture name or the size of type in points.
i. Nick: it is a groove out across the belly of the shank. Its position and number varies in different type font. In different type fonts, but all the types in one font have a similar nick. Its help the compositor in the correct placement of types in a stick while composite. Sometimes, its gives and additional nick is provided at the back of the small capital letters to distinguish them from the lowercase letters c, o, s, w and z.
j. Belly: the front side of the shank carry nick is called belly.
k. Feet: two pillars at the bottom of the shank on which the types stand. They are separated by a groove between them. One feet is located at the bottom of the belly side and other at the bottom of the back of shank.
l. Groove: it is a cut between the feets of a type and runs across the full width of the type. While casting type a ‘jet’ or ‘tag’ is formed at the bottom of the type which is broken off later and the type is plained or grooved at the bottom. In some casting machines ‘tag’ is automatically broken and the bottom of the type is shaved plain. The types produced one monotype composition casters do not have groove of any kind.
Back of shank: it is the opposite side of belly of a shank having head of the type at the top.
Sorts and glyphs: stored letters and other symbol (called sorts in mechanical systems and glyphs in digital systems).
Special character/ kerned letter: when an overhanging portion of a letter which rests on the shoulder of subsequent type in composition. It is not ligature type, ligature is two or more connected letters on the same type body. Whenever any portion of the printing face extend over the shank (type body) is called kerned letter, these are commonly found in italic faces.
How to make a metal type: metal type based on a matrix and hand mould in casting. There are three stage to get metal movable type.
a. Punch-cutting: punch cutting is a craft used in traditional typography to cut letter punches by punch cutter as the first stage of making metal type. Punch-cutter is made of steel and carry letter shape would be used to make copper matrix into letter shape mould to cast metal type. Mould has depth and metal type would be used in two dimensional onto the paper, so angle and depth should be well finished.
Process: the punch-cutter is a tool which has outline of a letter at the one end of the steel bar. It can be transferring outer shape of the punch or cut directly but the internal curve need more sharpness (exact depth), to solve this problem can be done with cutting tools, a counterpunch which has internal negative space is used to create counter depth around the glyph. Example is ‘O’ black line is in round shape is called outline and space between in outline is negative space, so punch-cutter only cut the outline but counter punch is struck into the face of the punch, the outer form of the letter is then shaped using files. A counterpunch could be used to create this negative space, not just where the space was completely enclosed by the letter. Punch is ready then make a test before use is called smoke proof.
Smoke proof: An open flame (candle) is to transfer the soot from onto the punch to make a smoke proof, soot like act as ink or coating, then punch cutter makes an imprint on a price of paper.
b. Matrix: matrix a copper mould carry a letter shape which is used to cast a metal type. A metal type used in letterpress printing. After punched a matrix by punch cutter could then be cleaned up and cut down to the width of the letter to cast, it is called ‘justification’ and sets the width of the letter when cast. A matrix is under unjustified is called ‘strike’. Large typeface and wide design, were not easy to punched by punching since, so alternative methods used woodblock were punched into metal soften by heating, or carefully casting type or matrices in sand, clay or plaster. Early nineteenth century was William caston find one solution is matrices formed by cut-out layered sheet to avoid this problem. The completely solution is electrotyping and pantograph engraving was come in mid-nineteenth which was displaced manual punch-cutting.
c. Casting: casting is a manufacturing process in which a liquid material is usually poured into a mold, which contain a hollow cavity of the desired shape. The matrix of one letter is inserted into the bottom of an adjustable-width hand mold. The mold is clamped shut and molten type metal alloy (lead, tin and antimony) is poured into a straight-sided vertical cavity from the top. When the type metal is sufficient cooled, the mould is unlocked and a rectangular block approximately 4cm long called, a sort. Excess casting on the end of the sort, is called tang, after removed excess casting, type is ready to use. The matrix can then reused to produce more copies of sorts.
Lithographic Plate making material:
The material for Litho plates consists of the metal used for the plate, the mixture of substances used for coating them, and the chemicals used for processing them.
Lithography plate are chemically maintains by the principle that grease (ink) and water generally do not mix.
Standard thickness range from 0.0055 to 0.020 inch (0.14 to 0.51mm) and sizes go up to 59X78 inch (1.5X2.0 mm).
a. 0.28 mm
b. 0.94 mm
c. 0.67 mm
1. Aluminium: commonly used today. The lightness and strength of aluminium alloys make them more suitable although pure aluminium is not strong, its alloy have great strength. It is ductile, malleable fairly soft and light weight. It is a better conductor of electricity than copper. Both aluminium and zinc are grained to increase the capacity to hold water and image. It is protect against corrosion by atmosphere.
We have already seen that while copper is hydrophobic, aluminium is hydrophilic
2. Chromium nickel: these two metals are their corrosion resistance. In order to improve the wear and tear one of the metal to electroplated on stereos, electros bimetal, Litho plates and gravure plate cylinder.
3. Copper: it used in letterpress, lithography and gravure. It provides fine line and halftone blocks, cylinder for gravure.
It high conductivity of heat and electricity is an outstanding property.
A thin coating in steel inking rollers a presses.
Photographic films:
1. Lith film: Lith film is a high contrast, high quality film, usually with orthochromatic dye emulsion. It is one of the oldest of the current film technologies and its use is declining due to complex bath processing required in the process, especially in controlling the correct strength of the developer.
Most traditional photographic material is based on chemical compound of silver-producing light sensitive material in two main type paper based, known as bromide, and film based, as negative and positive.
It became transparent in the unexposed area, whereas paper remains opaque.
Films are made-up of light-sensitive material emulsion, consisting of silver helide salts and gelatine coating on a stable base. Silver-base film material are colour-sensitive, reacting normally to the ultra-violet, blue-violet and between regions of the spectrum. In order to extend this colour sensitive, colour dyes are added. The two most common films.
a. Orthochromatic films: orthochromatic films has an extended color spectrum, going from between blue-voilet, blue, green, yellow, through to orange, but not include red.
b. Panchromatic films: panchromatic films is sensitive to the whole visible spectrum, form blue-voilet through to red, it can be operated in total darkness.
It stored in dark-green light.
The newer generation of color scanner and laser image setter use are red sensitive film which require a cyan safelight.
This lith films used in conventional camera, which produce the whole tonal range.
2. Rapid access film: rapid access film has become much more popular than lith, due to the fact that keeping chemicals in balance is less critical in rapid access than in lith processing.
3. Third generation (daylight operated film): it insensitive to all area of the color spectrum other than blue.
It stored in red, orange and yellow safelight.
4. Fourth-generation films: it is good quality film and sharpness.
It is available as a conventional camera based option or for image setter and scanner depending on the exposure source used -.g- NeNe, IR laser etc.
Types of graphic arts films/ photographic films:
1. Color sensitive: orthochromatic, panchromatic, blue sensitive films.
2. Contrast gradient: high contrast (lith films), low contrast (continuous tone) films.
3. Effect of light on silver emulsion: more darkness (conventional emulsion) or less density (direct positive emulsion).
4. Base material and thickness:
Color sensitivity:
Color sensitive, meaning that they are sensitive to specific colour or colours of light. Normally, the sensitive of silver helide emulsion is limited to the ultraviolet, blue violet, and regions of the spectrum. Extent the colour sensitive of the emulsion, dyes must be added.
Colour sensitivity become three emulsion types:
1. Blue-sensitive films: it blue sensitive films and it does not record red or green. It (colour-blind) film and it store easily. It suitable for making both halftone and line image from black and white copy, gravour positive.
2. Orthochromatic film: film is used to make halftone and line for image from black and white reflection copy, black and white continuous tone film. It can be used for any purpose other than making colour separation from full-colour copy.
It most widely used photomechanical film, for both line and halftone work.
3. Panchromatic film: it used for making both continuous tone and direct screened colour separation.
Used for separation coloured original.
Contrast:
The tonal different between highlight and shadow areas of an image represent its contrast. Film emulsion records the tones of a grey scale.
For film contacts the grey scale is placed on the film in the contact frame and is used to check the film contact for proper exposure and development.
1. High-contrast graphic arts films: high-contrast graphic arts films t as lith type film.
2. Continuous-tone graphic arts film: lower contrast than lith film.
FILM BASE:
Film base coated equally and stable according job requirement different thickness available.
1. Anti-stress layer: this thin top coating or super coat reinforced the emulsion layer helping to maximize scratches.
2. Emulsion layer: this is the gelatin layer holding the light sensitive layer of silver helide grains.
3. Base material: it prepared plastic layers are few material.
4. Substratum layer: it weak mixture of gelatin and base material and it adhesion is for required.
5. Anti-helation backing: selected dyes are dissolved in gelatin and coated onto the back of the base material, this dyes are absorb any light and increased by tinting the base material with grey colour. It protect film curling in during exposure.
FILM SPEED:
Film is term describing the time response to exposure.
Blue sensitive film will be slower than panchromatic film.
FILM EMULSION: The silver emulsion used on sensitized material consists of a colloid such as gelation, silver halides, and additives.
1. Gelation: gelatine is a protein obtained from the tissues, hides, cartilage and bones of animals. The important specification for photographic use of gelatine are jelly strength, PH, moisture content and metal content of iron, lead, copper and alumina together with limits of ash and sulfer dioxide.
2. Silver helides: the important salts of silver chloride, bromide and iodide.
a. Silver bromide (AgBr): it most used of the silver paper and film products. It is usually the major portion of the halide salt in film and high speed or low fog action emulsion.
b. Silver iodide (AgI): it used generally in combination with other halides. It is for slow speed.
c. Silver chloride (AgCL): it is pure white powder and used on paper type emulsion.
The halides of silver are widely used the oxalates, nitrates, artrates and citrates of silver.
3. Additives of emulsion: the silver salts are colour sensitive inherently to the blue portion of the spectrum only. To increase this sensitivity to red and green, colours sensitizing dyes are added to the photographic emulsion. These sensitizing dyes are absorbed by the silver helide.
Preparation of the emulsion:
a. Emulsification:
1. Soaking and dissolving a portion of the gelation.
2. Addition of bromide and iodides used in precipitation of the silver helide and forming silver helide crystals.
3. Addition of silver salts (nitrate) can be added either rapidly or slowly. If it is a added very slowly, the size of the silver helide crystals will be considerably larger than when the silver nitrate solution is poured in at once.
b. Physical ripening:
1. Recrystallization of emulsion by heating.
2. Addition of the remaining gelatine and chilling.
c. Washing of the emulsion:
1. Washing to remove the emulsion of unwanted salts.
2. The formation of ‘noodles’ by forcing the chilled gelatine through a wire screen.
d. Second reopening:
1. Reheating, which referred to as after-reopening or second-reopening to recrystallize the silver salts.
2. This do not effect size but increase the sensitivity.
e. Doctoring: addition of special chemicals such as optical sensitizing dyes, preservatives, stabilizers, spreading agents, anti-fog agents, hardening agent.
These materials are primarily used to create printing plates, negatives, positives, and image carriers for various printing processes:
A typical film consists of several layers:
1. Main Base (Support Layer):
a. Provides mechanical strength.
b. Usually made of cellulose acetate or polyester.
2. Stripping Layer:
a. Allows separation of the emulsion from the base (used in offset or litho plates).
3. Anti-halation Coating:
a. Prevents reflection of light back into the emulsion.
b. Ensures sharpness and prevents "halos" around images.
4. Light-sensitive Emulsion Layer:
a. Contains silver halide crystals suspended in gelatin (traditional) or photopolymers.
b. Reacts to light to form the latent image.
5. Protective Coating:
a. Thin layer of gelatin or polymer to protect the emulsion from scratches and handling damage.
a. Used for creating positive images from negatives.
b. Can be photographic papers with high contrast or special coatings for plate making.
Examples: Bromide papers, litho positive papers.
a. Developers: Chemicals that reduce exposed silver halide to metallic silver, making the latent image visible.
Example: Metol, Hydroquinone, Phenidone.
b. Reducers: Remove part of the silver image to lighten dense areas or create tonal effects.
Example: Ferricyanide, Sodium Thiosulfate.
c. Intensifiers: Increase image density after development without further exposure.
Example: Mercury intensifier, Silver intensifier.
Different printing processes require specific light-sensitive materials:
Printing Process
Light-sensitive Material
Remarks
Offset (Lithography)
Photopolymer plates, diazo plates
Used for direct-to-plate exposure from film or digital images
Flexography
Photopolymer plates
UV-sensitive for relief images
Gravure
Positive or negative films
For etching image into cylinders
Screen Printing
Photo emulsion
Direct exposure on stencil mesh
Letterpress / Relief
Positive films on metal or polymer plates
High contrast films for sharp relief
UNIT-2
Paper Substrates & Non-Paper Substrate for printing & Packaging:
Varieties of paper:-
1. Newspaper print-absorbing ability, quick drying, 75% mechanical wood pulp only coarse-screen halftone, good bulk and opacity lacks strength, yellow and brittle colour, cheaper paper. (newspaper paper)
2. Mechanical printing paper: chemical wood pulp writing, paper, one side smooth and thinner. (Magazine and advertisement (catalogue) with furnish by super calendering process.
3. Machine finished: machine finished paper is one side smoother and not good for fine halftone picture. It is finish by the calendering unit and suitable for book work and available in suitable sizes. (tissue paper and fine paper)
4. Super calendered: it is thin light and smooth and suitable for 100 lines upto screen rulling, printing multicolor jobs and magazines & wall calendars. It has quick drying ink availability and extra polish & smooth as compare to other papers.
5. Wood-free-chemical wood pulp, good color for magazine, leaflets, Booklets, reports 135 gsm. (cotton and linen paper).
6. Bible paper: Bible paper is thin white opaque paper, it is made rags (cotton or linen) with sulphite, Tio2, china clay to obtain opacity.
7. Antique paper: Antique paper is fibre contain from esparto and preparing by Sulphite & soda process with up to 15% china clay, rough surface short fibre. It is available 70 to 90 gsm. It is not much presses by glazed cylinder during the manufacturing process, therefore, it is thick soft, light and less strong but has uneven surface. It is not suitable for writing purpose.
8. Catridge paper: the surface is uneven but strong suitable for drawing and painting and screen printing. It is unsuitable for halftone and multicolor.
9. Offset cartridge paper: this quality is hard sized: dimensionally stable, non-fluffy paper. The finish can be machine finish or super calendering esparto, sulphite or soda with china clay, Tio2.
10. Art paper: fine halftone, art books, technical journal, pamphlets.
11. Chromo paper: one side coated, printing of labels, stickers, posters, book jackets.
12. Cast coated: paper have mirror like glossy, it is only used in USA.
13. Imitation art: not coated, writing paper.
14. Bond paper: it is prepared from rag pulp and cotton etc. Due to the vehicle of the ink could not penetrate easily in the surface of the paper therefore it should be medium and have quick drying properties. Matt surface, more opaque, it is used for letter heading, printing line diagrams and text matter only.
15. Ledger paper: ledger paper is strong and durable writing paper made from heavy quantity of rags and cellulose additives. It is used in banks ledger. It is available in various colors like as light blue, light green, yellow, Off-white for very long period.
16. Feather weight paper: feather weight paper is uneven surface and light weight paper. It is prepared from wood and grass pulp by mechanicals and chemicals. It is suitable for book work but halftone screen not clear print due to its uneven surface.
17. Machine Glazed paper: it is made smooth by the machine instead of any sizing and calendering process.
Kinds or board
1. Pulp board: pulp board is manufactured in a single-web, wood-free (200 to 750 micron) (wood like board) (wood for use exam time).
2. Triplex board: triplex board is made up of three layers white duplex board consists of two piles or webs. (Uncoated fine lynx swatch card).
3. Straw board: book binding, yellow-brownish.(register board)
4. Carton board: multi-ply board, test all quality control. (kraft paper)
5. Chip board: some straw but more smoother, flexible, making boxes, cartons, containers. (fine register used)
6. Mill board: mill board used for fine leather binding, library work, making split board.(capa board)
7. Paper board: one side increase printability. It is used for carton, two type board
a. Bending
b. Non-bending board.
Paper sizes
ISO: ISO system of paper size in UK and EUROPE is the ISO standard. It have dimensions in mm and international standard paper size.
ISO sizes divided into 2 category: ISO have three series A,B,C series.
A=general printing purpose like stationery and publication.
B= posters and wall charts
C= envelops.
It is regular sub-divisions 1: under root 2 and proportion of sides.
1. Side proportion of metric size
2. Sub-division
It is used in India follower by the British. It have dimension in inch.
Plastic: the plastic form a comprehensive family with a wide range of properties which can meet almost every requirement of the packaging industry. Plastic can be trailer made to meet a specific requirement of packaging or achieve a combination of properties. The can be divided into two main group:
a. Thermoplastic: when the contact in heat then it is loss in mechanical or physical properties and not reuse.
b. Thermoset: it soften on the application of sufficient heat, but hardness cooling.
Plastic are used for making rigid containers, flexible container, films and laminations.
Advantage:
a. Plastics are light and less expensive than other packaging material.
b. They have better barrier properties moistures, odor oxygen and other glass.
c. They are resistant to most chemicals, non-toxic in nature.
d. Plastics can be processed into desired shapes of forms like films, sheets, bottles, tubes, pouches and crates.
e. Plastic material saves cost in storage and transportation because of less weight and less secondary packaging.
f. They do not promote bacterial growth.
g. Single-sever cost for food items, such as ketchups and small unit pack like sachets can be made at less cost.
h. Plastic packages are prefer-proof, tamper evident break resistant, corrosion resistant and leak proof.
i. Plastic packaging do not pose any major disposal problem since almost all the plastic can be recycled.
Limitations of plastic packaging:
a. Some chemicals attach particular plastic.
b. Plastic are not total barriers to gases and water vapour, although some new barrier plastic have improved oxygen gas and odor impermeability.
c. Less abrasive resistance and puncture resistance.
1. Polypropylene (PP): polypropylene (PP), also known Poly-propene, is a thermoplastic polymer used in a wide variety of applications including packaging and labelling, textiles (e.g. ropes, thermal under wear and carpets), stationery, plastic parts and reusable containers of various types, polymer banknotes.
Most commercial polypropylene is isotactic and has an intermediate level of crystallinity between that of low density poly-ethylene (LDPE) and (HDPE).
Properties:
a. The monomer units is prop-lene.
b. It is harder and stronger than polyethylene.
c. Very low density (0.9gm/CC).
d. High stiffness and rigidity.
e. High tensile strength.
f. High resistance to chemicals and heat.
g. With sand continuous service temperature of 90 and intermediate temperature of 120C.
Application:
a. Packaging of textiles product.
b. Bakery product.
c. Packaging of shack foods, dry fruit etc.
d. For manufacturing liner of bags, lining material for TV.
e. For making ropes, fibers.
f. High transparency BOPP.
BOPP (bi-axially oriented polypropylene): which polypropylene film is extruded and stretched in both the machine direction and across machine direction. Bi-axially orientation increases strength and clarity.
Features of BOPP films:
a. Excellent clarity.
b. Good dimensional stability and flatness.
c. Low electrostatic charge.
d. Good barrier to water vapour.
e. High gloss.
f. Recyclable.
g. Resistant to oils and greases.
h. Not affected by moistures and does not wrinkles or shrink with environment charges.
It has range from 15 to 50 microns and most commonly 15 to 30 microns.
Applications:
a. Flexible packaging
b. Pressure sensitive tape.
c. Printing and lamination.
d. Stationery
e. Metallizing.
f. Flower sleeves.
g. Cable wrap and insulation.
h. Overwrapping of cigarette, carton (10 to 12 microns).
2. Polystyrene: it is hard, rigid and almost glass like. It is brittle and more easily broken then some other polymer not particular weather resistance so that usually stable for contact use.
a. It is transparent in nature.
b. Light weight.
c. Odorless, non-toxic.
d. Unlimited range of color.
e. Low shrinkage.
f. Little tendency to wrap.
a. For making not drink cups, toys, combs, household articles etc.
b. For making radio and TV bodies.
c. For making tiles.
d. They can be easily decorated by printing Metalishing, hot stamping etc.
3. PVC: polyvinyl chloride (PVC) has a linear structure similar to polyethylene but with a chlorine atom replacing a hydrogen atom on alternate carbon atoms.
It is third most used than polyethylene and polypropylene. It is not recommended for use above 70 celcius although it can be taken to 80 for short periods.
a. PVC is a hard horny material.
b. It is a thermoplastic polymer.
c. Glass like clarity and good mechanical strength.
d. Resistance to gases like oxygen and carbon-dioxide or water and chemicals.
e. Retention of flavor.
f. Lower weight/ volume ratio lower.
a. In the manufacturer of rain coats hand bags, curtain clothes, toys.
b. As a good insulating material in wires and others electrical goods.
c. PVC films the textiles industries as a replacement of cellophane film for packaging of textiles.
4. Polyethylene (PE): polyethylene is a type of polymer that is thermoplastic, meaning that it can melted to a liquid and remolded as it return to a solid state. It is chemically synthesized from ethylene, a compound that is usually made from petroleum or natural gas.
Uses: film, packaging, bags, pipins, industrial applications, containers, food packaging, lamination liners, wire cable. It can be harmful to human and to the environment.
Classification: it is classified into several different categories based mostly on its density and branching. It grade are HDPE, LLDPE, LDPE. It has density value ranging from 0.91 to 0.925 g/cm3, 0.918 to 0.94 g/cm3, 0.935 to 0.96g/cm3.
a. LDPE: it by the high pressure polymerization of ethylene. Its comparatively low density arises from the presence of a small amount of branching in the chain (on about 2% of the carbon atoms).
It is translucent to opaque and it is slowly attacked by strong oxidizing agent and some solvents will cause softening or swelling.
b. High density polyethylene (HDPE): HDPE is prepared from ethylene by a catalytic process. The absence of branching results in a more closely packed structure with a higher density. It higher chemical resistance than LDPE.HDPE is also somewhat harder and opaque. It is strong resistance to moisture, and most chemicals & relatively stable when heated.
Application: it is used to make bottle for milk, juice, water, laundary product, drum and other container. For many kinds of household and industrial chemical. The wrinkly kind of soopy.
c. (LLDPE): it is a sustaintially linear polymer (polyethylene) with significant numbers of short branches, commonly made by copolymerization of ethylene with longer chain olefins.
Features:
a. High strength, durable, weather resistance to high temperature oxidizing, non-toxic.
It is used for plastic bags and sheets, plastic wrap, stretch wrap, pouches, toys, covers, lids, pipes, buckets.
5. Polyethylene terephthalate (PET): it is a thermo-plastic polymer resin of the Polyster family and is used in synthetic fibres, beverage, foods and other liquid containers.
Depending on its processing and thermal history, PET may exist both as a morphous (transparent) and as a semi-crystalline polymer. The semi crystalline material might appear transparent (particles size <500nm) or opaque and white particle size up to a few microns).
It is used for soft drink bottles. Or certain specially bottles, PET sandwiches an additional polyvinyl alcohol layer to further reduce its oxygen permeability. These properties flexible food packaging and thermal insulation such as “space blanket”.
PET to make packaging tray and blisters.
It is produced from ethylene glycol and dimethyl terephthalate (C6H4 (CO2CH3)2) or terephthalic acid.
PACKAGING MATERIAL
1. Paper and paperboard:
a. It is cheaper and easily available.
b. They provide attractive look of the product.
c. Easily printable.
d. Recyclable and biodegradable.
e. Light and bulky.
f. Cheap.
g. Easily deformable/ die-cutting.
h. Printable (any process can be adopted).
Limitation:
a. Resistance to mechanical impact is comparatively less.
b. Resistance to climatic hazards is also limited.
2. Corrugation board: resists mechanical impact, increase the time of impulsive forces.
Wood: wood pulp (sulphate process – corrugated board).
Components of corrugated board
a. Liner
b. Fluting
c. Adhesive
The process of running reels of paper into corrugated board is complex process the basic process is to take fluting paper, give it its characteristics wave formation, then stick it to one liner, at a later point in the machine the second liner is applied to fluting, giving to a finished pieces of corrugated board it is than curved cut into the required sizes.
Reel stand of the corrugators hold two reels of paper that are used to product corrugated board. There is at least one reel stand per liner and fluting a corrugated board.
Single facer could be considering the heart of corrugators in this section of the machine the actual wave formation of fluting paper is formed, and bonded to one liner surface among single face paper. Single face that has one liner and one fluting formation. Fluting paper is fed into the single facer from fluting reel stand. The paper passes through a set of corrugated rolls which are like two toothed roller. These rollers form and set the fluting paper into characteristic wave shape. At the same time, from the opposite side of the single facer, the inner of corrugated board is being fed into single facer forming reel stand.
a. Liner: craft paper of above 80 gsm up to 225 gsm is used preferably. The outermost liner used for a box should be of maximum grammage. Their function are.
1. Resist hazard like punter, burst, abrasion tear etc.
2. Properly hold the fluting medium when one combines.
3. Resists moisture or water either outsider or inside depending on the nature of product to the packed.
4. Be amicable for printing.
Water proof paper such as btumen coated, wax coated are also used for liner.
b. Fluting: paper obtained from semi-chemical pulp process are used which proved the good rigidity to the board. Its function are to:-
1. Provide necessary cushioning desired.
2. Provide rigidity to board.
3. Contribute to resistance to bending under stress.
The grammage of fluting medium may be in the region 80-150gsm.
c. Adhesive:
1. Usually starch based adhesive are used for joining the outer liner.
2. Sodium silicate are also used.
Classification: board consisting of one or more shades of fluted paper struck to a flat sheet of paper or board between several liners usually craft, this has following:
a. Single face corrugated
b. 3-ply corrugated
c. 5-ply corrugated
d. 7-ply corrugated
3. Flexible materials:
a. Paper coated with heat sealed thermoplastics: resin can be used for strip packaging of tablets which are hot sensitive to moisture. It can also be used for making pouches. Where pharmaceutical powders may be packed. The main advantage of paper as strip sealing material is its low cost.
b. Cellulose films: it are generated from cellulose and are used for packing pharmaceuticals. The cellulose film is given a specific coating treatment depending on the essential properties, it is required to offer nitrocellulose and poly-vinyledene chloride are used for coated films. It is surface present an usually glossy mirror lie finish and it can also be reverse printed. Polyethylene when laminated to cellulose film imparts strength and provides gas barrier properties. Thus satisfying the requirements that any one this film will not offer independently. This laminate can be sandwiched printed completely protected from abrasion and stretching. Pure cellulose film would not be suitable for packaging, being too rigid and brittle, in normal manufacture, it is suitably treated with softner, the composition and quantity of which influence the properties of the films. Thus, treated it is grease proof and can also be made moisture proof and water proof by adding suitable coating. It is printing qualities are very good. It trends itself readily to printing by gravure and flexography process.
c. Polythene film: it is one of most widely used packaging materials. Polythene resins from which the film is made is prepared from ethylene gas. The low density type of film has auxiliary and extremely flexible. The high density materials are stiffer-less ductile and permeable but more heat resistance. One of the outstanding qualifier of polythene films is that very high rear strength. But the best known characteristics is their extreme toughness polythene films is not as transparent as cellulose but strides has been made towards the development of types with higher transparents and surface gloss. Polythene film is process of gravure of flexographic process but treatment of the film is necessary.
Metal in packaging
Metals are widely used in the packaging industry for manufacturing all types of containers and other application to food industry. The material in regular use are- tin plates. Aluminum and black plate.
a. Aluminum foil: aluminum in the form of heat seal laminated foil has found extensive application in the packaging of pharmaceutical tablets. It can be classified into two group namely---
1. Foil coated with thermoplastic synthetic resinous compounds.
2. Foil coated with or laminated to thermoplastic film.
Film laminated to polyethylene has the advantage of offering double protection that form aluminum foil and for polyethylene because of its good heat seal properties polyethylene is generally used as the innermost layer to produce what is called a weld seal. Reverse printed cellulose acetate laminated to foil offer the advantage of a scuff resistance.
Flexible packaging material commonly used for bakery products can be classified as—
1. Natural cellulose: based such as paper and cellulose. Glossing grease proof paper.
2. Synthetic polymeric based materials such as low and high density polyethylene, polypropylene and their laminated.
3. Metal foil: based aluminum foil laminates and metalized polyester or poly-laminates.
4. Laminated of above 3 group packaging material depending upon their end used.
b. Foils: metal foil is an old packaging material with many new used. It is low made almost exclusively of aluminum through used as laminated or liner for a variety of purpose. It’s is main sphere is still in the production of food being completely moisture and odor proof. Foils makes an excellent container for dehyolraded foods. The principal characteristic which recommend aluminum foils for various packaging application are—
1. It is impervious to moisture and gases.
2. Insect proof.
3. Grease proof.
4. Shrink proof.
5. Non-absorptive, odorless and tasteless.
6. It is hygienic, non-toxic, resistance to corrosion and non-ageing.
Foils are strong folds neatly with precision and easily handled on machine. Foils combined with non-metallic sheets varying from heavy paper board to thin transparent. Cellulose or polythene sheeting offer a large range of container or wrapping to the packaging industry.
Plastics
1. Polyethylene
a. High molecular high density.
b. High density (HDPE).
c. Low density (LDPE).
d. Linear low density (LLDPE).
e. Shrinkable film.
f. Tape (HD).
2. Polypropylene:
a. PVC
b. Polystyrene
c. Polyester
3. Cellulose film.
Paper inks, Coatings & Varnishing for printing & Packaging Applications:
PRINTING INK
Definition: ink is a liquid or paste that contain pigment of dyes and is used to color a surface to produce an image, text and design.
Two types of ink:
1. Paste: letter press, offset, screen
2. Liquid: gravure, flexography.
Ingredient of inks:
1. Colorant: (a) pigment (b) dye
A. Pigment used in paste ink.
B. Dye used in liquid ink
2. Binders: varnish or vehicles which consists of oils, resins or alkyds.
3. Carrier substance: solvents
4. Driers
5. Ink additives or modifier
a. Plasticizers
b. Waxes
c. Wetting agents
d. Anti-set off compounds
e. Shortening compounds
f. Reducer
g. Stiffening agent
h. Anti-skinning agents
1. Pigments: pigments made from various solvent such as water, oil, alcohol, and acid like as (sulphur, silica or china clay can be combined with either soda ash or sulfate salts).
a. Organic: soluble dyes, insoluble dyes.
b. Inorganic: naturally occuring, synthetic.
2. Binder: it is bind of pigment to each other.
Vehicle = varnish and additives.
Varnish + resin + drying oil
Vehicle: vehicle is to carry the pigments to the paper surface and protect the image during life span of the print, in adhesion to the paper surface.
Resin: resins are organic compounds and may be blended or chemically combines with ability to be dissolved in some organic solution or natural drying oil in order to improves drying, hardness, scratch resistance and gloss of ink.
Drying oil: oil from animal, vegetable, linseed oil, olive oil which extracted from the seeds of flex plants. These oil absorb atmosphere oxygen and polymerized.
Non-drying oil: it include mineral oil which are high boiling extraction of petroleum.
3. Dries: it is used to accelerate the printing ink after it is transferred on the substrate. Drying oil dried by adding small amount of driers, they are soaps of such metals as cobalt, maganese, lead, cerium or zircomium.
a. Cobalt: disadvantage: discolor tint and white ink. It is liquid form.
b. Maganese and lead dries: these are prepared by grinding (mg) + (lb) in linseed oil varnish. It is paste form.
c. ‘grapho’ or perborate: oxidizer that furnish oxygen.
4 Ink additives (modifiers):
a. Waxes: it is used in vehicle to impart rub resistance to dried ink film. It is reduce set off, improve water resistance, slow drying, reduce tack and viscosity.
b. Anti-skinning agent: agent drying of the ink in litho ink.
c. Antioxidant: prevent form oxygen.
d. Plasticizers: it is high boiling that is low volatility solvent whose main purpose is impart flexibility otherwise the ink. Make resin softer and flexible.
e. Wetting agent: such as fatty acid and alcohol.
f. Anti-set off: prevent from set-off printing problem.
g. Shortening: reduce ink flying or misting. It is a wax.
h. Reducer: ink to make thin.
Properties of ink
1. Tack: it is stickness of ink. Tack may be ability of ink to act as an adhesive.
2. Viscosity: the speed of at which various liquid flow will vary widely, the resistance of the liquid to the force trying to move them.
3. Tixo-trophy: it is used in lithography ink.
4. Length: it is property associated with the ability of an ink to flow and form long filament.
5. Transparence & opacity: how many light and dark ink.
Ink term:
1. Baking: away from fountain or handing back.
2. Strike through: soaking of an ink through the paper and discoloring the reverse side of it.
3. Show through: ink visible in back side.
Each printing process requires ink specially formulated for the mechanics and chemistry of the process.
'Letterpress'. Letterpress uses paste inks whose tack varies according to the speed of the press (though ink of moderate tack is generally preferred), and which typically dry by absorption, oxidation, or evaporation (or a combination of drying methods). The letterpress process, however, is falling into disuse in favor of other printing methods, such as offset lithography and flexography (letterpress now accounts for less than 5% of all printed packaging, for example). The varieties of ink used in letterpress printing are rotary ink, heatset ink, moisture-set ink, water-washable ink, newsink, and job ink. Rotary inks are commonly used in letterpress printing of books, magazines, and newspapers. Book ink is a somewhat fluid ink, and book inks are formulated to be compatible with the surface of the book paper on which it is to be printed. For example, a paper with a high degree of surface hardness requires a fast-drying ink. Rotary inks also include heatset inks. (See Rotary Ink.) Moisture-set inks, as was mentioned earlier, utilize glycol vehicles that set fairly fast and are odor-free, which is why they are frequently used in printing food wrappers and packaging. (See Moisture-Set Ink.) Water-washable inks set very fast and are water-resistant when dry, and are used to print on kraft paper and paperboard. (See Water-Washable Ink.) Newsink, used for printing on newsprint, dries primarily by absorption of the vehicle into the substrate, and consequently needs to have a fluid consistency. Like newsprint—which is made from inexpensive and somewhat low-quality groundwood pulp—newsinks also are made from inexpensive and perhaps less than optimal raw materials. The faster the press, the thinner the ink must be. An ink that is too thick will smudge when the paper is folded or generate ink setoff. An ink that is too thin can soak all the way through the paper, producing a printing defect known as strike-through. Most newspapers, however, although originally printed by letterpress, are now printed using web offset lithography. Job inks have a medium body and a drying process that can be used on as wide a variety of paper as possible. Job inks tend to be a standard default ink in many letterpress print shops, and need to be compatible with many paper types and many types of presses. Letterpress printing processes also use various other types of inks on occasion, such as non-scratch ink that is needed for labels, covers, and other end uses that require a scratch-resistant ink, quick-set inks, and high-gloss inks.
'Offset Lithography'. The suitability of the offset lithographic process for printing on a wide variety of surfaces has resulted in a large number of inks available for the process. Typically, lithographic inks (which are paste inks) are more viscous than other types of inks, and since the ink film is thinner with offset printing, the pigment content must be higher. (Offset presses deposit ink films that are about half the thickness of films deposited by letterpress presses.) And since offset lithography is premised on the fact that oil and water do not mix, inks designed for the process must contain significant amounts of water-repellent materials.
Sheetfed offset presses primarily use quick-set inks, which dry rapidly without the need for additional equipment, such as drying ovens necessary for heatset inks. Some sheetfed offset presses, however, do use various radiation-curing devices, as is needed for super quick-set infrared ink, ultraviolet curing ink, and electron beam curing ink.
Lithographic inks primarily set by a combination of absorption of oil-based vehicle components into the substrate, followed by oxidation and polymerization of the remaining components of the vehicle. Web offset lithographic processes utilize higher press speeds, and consequently need to lay down an ink film more rapidly. The ink must be absorbed into the substrate more quickly to avoid smudging and setoff during folding processes at the end of the press. Hence, web offset inks tend to be more fluid and have less tack than sheetfed lithographic inks. Newsinks have seen improvements recently, especially from soy ink, which is made from the latest development in vegetable oil vehicles, soybean oil. Web presses also utilize heatset inks, which dry as the printed paper web is passed through a high-temperature drying oven. Web presses also utilize radiation-curing methods.
The most important criterion for offset inks, however, is their insolubility, as they must resist bleeding in the presence of the water-based press dampening systems. Problems with the drying of offset inks that dry by oxidation include emulsification of the fountain solution into the ink. An excessive amount of dampening solution (or one with a high pH) can impede proper ink drying, and the use of papers with a low pH also has a deleterious effect on ink-drying properties. (See Acid Paper and Alkaline Paper.) Lithographic processes are also well-suited to printing on surfaces other than paper. Lithographic inks used for printing on metals (such as the printing of cans and other metallic packaging) contain synthetic resin varnishes that dry in high-temperature ovens. Letterset inks and waterless inks are also available for recent developments in waterless offset printing processes.
'Flexography'. Flexographic presses typically use liquid inks that possess low viscosity and dry primarily by evaporation of the vehicle. Flexographic presses use either water inks (typically on non-absorbent substrates such as polyolefins and laminated surfaces and, in the past, on various types of paperboard) or solvent inks (for use on surfaces such as cellophane). Water-based ink vehicles are composed of ammonia, protein (solubilized by amine), casein, shellac, esterified fumarated rosins, acrylic copolymers, or mixtures thereof. They have a high degree of printability, perform well on the press, and clean up easily. Water-based inks are used extensively in flexographic newspaper printing as they are almost totally smudgeproof. Water-based flexographic inks, however, have a longer drying time on less absorbent substrates and a low degree of gloss. Water-based inks are undergoing further research and development due to the desire to decrease the dependence on solvent-based flexographic inks, which contribute to air pollution. The vehicle for solvent-based inks is a solvent-resin mixture, formulated to suit the surface to be printed, as well as the press plate and other parts of the press it will be in contact with. Incompatible solvents can distort and damage the rubber flexographic plates. The solvent is made up of an alcohol—ethyl, propyl, or isopropyl. To produce optimal resin solubility, glycol ethers, aliphatic hydrocarbons, acetates or esters may be added. These additives also contribute to the desired viscosity and drying speed. The resins themselves must be chosen with care, as they affect the end properties of the ink. Typical resins used in flexographic inks include acrylics, cellulose esters, nitrocellulose, polyamides, modified rosins, and ketone resins.
'Gravure'. Unlike most inks produced for other printing processes, gravure inks comprise a pigment, a binder to keep the pigment uniformly dispersed and to bind the pigment to the surface of the substrate, and a solvent to dissolve the binder and eventually evaporate away in the drying phase. Depending on the solvent used and what it is capable of dissolving, a wide variety of materials may be used as binders. They are chosen according to the end properties desired, such as gloss, resistance to water or other substances, flexibility, etc. Some binders, such as film formers, dissociate themselves from their solvents rapidly after printing, which enables the ink to dry quickly. Finishing operations such as rolling, diecutting, etc., can be performed immediately as is the case with types of wrapping and packaging. In rotogravure printing, the most important considerations in terms of solvents are their dissolving of the film-forming resins, the rate at which they dry, whether or not they have deleterious effects on previously-printed ink (as in multi-color jobs), their toxicity, and whether they release harmful vapors. Pigment particles must also be more finely ground than in other printing processes, lest damage be incurred by the gravure cylinder. As part of the effort to reduce the usage of solvent-based inks, water-based gravure inks are being developed, but have not yet met with resounding success.
'Screen Printing'. Screen process printing requires paste inks that are thick and able to print sharply through the screen. They must also perform well under the action of a squeegee. The binder added to screen process ink must be compatible with the surface on which it will be printed. The solvents used should also not be overly volatile, as excessively early evaporation would cause the remaining ink components to clog the screen. Screen inks typically utilize a drying oil vehicle.
'Ink-Jet Printing'. The inks used in ink jet printers—typically used for computer printouts, labels, etc.—consist of dyes mixed with a highly fluid vehicle or carrier that form very small drops, can pick up an electrical charge, and can be deflected properly to fall in the right place for the formation of a printed character or image.
'Copperplate and Die Stamping'. Copperplate printing is commonly used to print stamps, bank notes, securities, and other high-quality decorative applications. These processes utilize a somewhat viscous, heavy ink that allows the designs etched in the printing plate to be completely filled in, much like in gravure printing. The vehicles for these inks utilize light litho oils and fluid resins mixed with low-volatility solvents that evaporate very slowly.
'Electrostatic Printing'. Also called xerography, electrostatic printing is commonly found in photocopying machines and computer laser printers. The "ink" used in these processes—commonly referred to as toner—consists of a fine, dry powder coated with the desired color imparted by a colored resin binder. The important consideration is not only particle size, but also electrical properties, as electrostatic printing works by attracting particles electrostatically to a charged drum, the point of attraction on the drum being the printing areas.
Coatings and varnishes are applied on printed surfaces to protect, enhance appearance, or modify functional properties. Their main constituents include:
1. Binders (Resins):
a. Provide adhesion and film formation.
b. Types: Natural resins (shellac, damar), Synthetic resins (acrylics, alkyds, polyurethane, UV-curable resins).
2. Solvents / Thinners:
a. Adjust viscosity for easy application.
b. Examples: Water (for water-based coatings), alcohols, hydrocarbons, or acetone (for solvent-based coatings).
3. Additives:
a. Improve performance or appearance.
b. Examples:
4. Pigments / Fillers (Optional):
a. Used for colored varnishes or special effects.
b. Examples: Titanium dioxide, mica, or pearlescent powders.
a. Methods of Application:
1. Spraying – Even and thin coat, commonly used in offset or flexo printing.
2. Roller Coating – Suitable for sheets and continuous web printing.
3. Brushing / Dipping – Mostly for specialty or small-scale applications.
4. UV Curing – For fast-drying, high-gloss finishes.
5. Electrostatic / Powder Coating – Industrial applications.
6. Areas of Use:
a. Printed paper, packaging materials, cartons, labels, magazines, and books.
a. Protection:
1. Resist abrasion, moisture, and chemical attack.
b. Enhanced Appearance:
1. Increase gloss, brightness, or matte finish.
2. Provide smooth surface and depth of color.
c. Functional Properties:
1. Improve ink adhesion, durability, and handling.
2. Can add special effects like texture, embossing, or tactile feel.
d. Cost Efficiency:
1. Cheaper alternative to lamination in some cases.
1. Environmental Concerns:
2. Surface Sensitivity:
3. Limited Protection:
4. Drying Issues:
5. Cost:
UNIT-3
Cushioning Materials:
Cushioning materials: package cushioning is used to help protect fragile items during shipment. It is common for transport package to be dropped, kiched and impacted. These event may produce potentially damaging shocks, transportation vibration from conveyors, trucks, railroads or aircraft can also damage some items shocks and vibration are controlled by cushioning so that the change of product damage is greatly reduced.
Cushioning is usually inside a shipping container such as corrugated box. It is designed to deform or crush to help keep levels of shocks and vibration below levels that may damage produce inside the box. Depending on the specific situation, package cushioning can often be between 50 to 75 millimeter (two to three inches) thick.
Purpose of cushioning material: good are frequency transported from one place to another. These goods are sensitive to mechanical stresses. Hence, the good must be protected from damage due to impact, jointing or vibration in transmit. Ex: glass, ceramic, porecelain, electric products.
Mode of action cushioning material: cushioning materials absorb a proportion of the kinetic energy arising when the package suffers an impact.
Required characteristics of cushioning material:
1. Recovery: it ensure, that the package contents continue to be protected even when repeatedly subjected, to similar stresses. If recovery is too low. The breaking distance a centered exposure to stress such that resultance kinetic energy can be longer be absorbed and package may be damage.
2. Climate condition: these not must be insensitive to climate conditions such as moisture due to relative humidity, direct solar radiations and extreme variation in temperature. It protect from corrosion.
3. Interactivity: the cushioning material not package content should not interact and possibly impact each other properties.
4. Use of cushioning material should be effective, simple, environmentally compatible and cost effective.
Type of cushioning material:
1. Air bag: air bag consists of a plastic film which is inflated or fill cloth air when at not only the static lead generated by contents of package hear upec. Cushioning material. These are used in containers, rail road, freight cost and trucks.
a. Ease of handling.
b. Non-hygroscopic (moisture resistance).
c. Highly versatile (availability).
d. In sensitive to climate condition.
e. Good recovery.
2. Rubble film: they consist of two plastic films in which one is completely flat and other has round indentation. Once the necessary air. These are used inside packaging containers.
3. Rubberized fiber cushioning: this cushioning material it made from animal hairs or coconut fibre which are clean converted into material with vulcanized to form rapidly bonded sheet. These are in-sensitive to moisture and temperature and have good recovery. This material provides high quality protection.
4. Plastic form cushioning material: these are made from polystyrene (PS) poly-urethene (PU) and polyethylene (PE). These are available in flexible, semi-rigid and rigid forms.
5. Loose fill: some cushion products are flowable and are packed loosely around the items in the box. (Starch based foams).
6. Corrugated fibre board:
Factors considered for selection of cushioning material:
1. Sensitivity classification of the product: it is determined by ‘g’ value. 1g is the acceleration due to gravity 9.81m/sec. the forces, which usually applies to an object on earn.
2. Stresses during transport: the stresses arising during transport are second important parameters in a cushioning material. These stresses are highly variable and we do not know what type of stress- it will be the greatest stresses occur when dropped.
3. Static area load is important: the cushion is exposed to both dynamic and static forces during transport and cargo handling. During handling only the static stresses are known as the static area load acting upon a cushioning material.
Static area load = weight of packaging content/ working area (kg/cm2).
4. Recovery: recovery is the most important factor for the selection of cushioning material. If recovery is higher than the cushioning material will increase breaking distance and will absorb the kinetic energy and protects the product mom mechanical stress.
5. Specific weight: specified weight is started in kg/m3. It is a measure of the hardness of cushioning material. If the specific weight is more, then the hardness of cushion Aerials is more.
6. Resonance behavior: if the vibration frequency during transport reaches or equals the natural frequency of the packed, the resonance may occur. This will damage the product, so when transporting sensitive items, we should know and adjust the following.
a. Frequency value of the type of transport.
b. Natural frequency of the cushioning material.
c. Natural frequency of the packed product.
7. Stress range of the cushioning material: every cushioning material has a stress range. The effectiveness of the cushioning material is within this stress range.
Glue is prepared from the bones and skins of the animals by boiling with water. The first output is good quality, transparent “pearl glue”. The second output is “flexible glue”. The final output is of inferior quality, having bad smell and brown in color called as “scotch glue”. Glue named “cassava” has been recently introduced, which can be mixed with cold water and used.
These are made from (PVA) Poly Vinyl Acetate and are in white liquid form. These have good tackiness and high flexibility.
It is another synthetic adhesive made from copolymers, resins and waxes. It is 100% solid and is brought to working condition by melting is at 1600 to 1900 C
It is obtained from tree. It is thin, nearly in liquid form with low viscosity. It is specifically used in manufacturing of envelopes, labels, stickers etc.
UNIT-4
Miscellaneous Materials:
1. – Ware House, Types of Ware House – White paper Ware House, Printed paper Ware House
The warehouse is the place of practice where a printed and blank stock is handled to convert into finished product. There are two types of warehouse in nature
a. White paper warehouse
b. Printed paper warehouse
In this ware house only the unprinted sheets are stored and handled. From this ware house the paper goes to the printing press department for printing.
In this ware house only the printed sheets are stored and handled. After printing the printed sheets from the printing press department comes here for storing before it goes to the binding and finishing department.
2. – Covering Materials – Binding cloth, Buckram cloth, Rexene, Leather, Paper fabric, PVC
Binding Cloth
It is a very important material in book binding. It is used to cover the book and make it attractive, to reinforce spine edge of the book, to hold the straw boards with the book spine.
It is a closely woven cloth from good quality cotton fabrics. It is starched on one side. It is available in many colors but red, green and blue are popular. The gaps between the woven threads are filled up with pigment filler and finally heavily starched on one side. It prevents the penetration of glue from rough side to polished side.
It is superior quality binding cloth. It is closely woven and stiffened with heavy paste and glazed to avoid finger prints on cloth. Sometimes it is grained and embossed with different patterns to make the appearance attractive.
The closely woven cloth is coated with cellulose plastic. Due to this the Rexene becomes water and stain resistant. It is very strong and durable. Various attractive patterns are embossed on it. It is used for cheap account books, diaries, albums etc.
Leather is durable covering material but aloes very costly. It is very attractive and pleasant to handle. Mainly account books, ledgers and very rare valuable, costly books are bound in leather. Leather bound books are mostly decorated by gold blocking etc. leather is of mainly two varieties. They are skins and hides.
Skin means leather obtained from the small animals such as goat, sheep, calf and pig. Hide means the leather prepared from matured animals such as bullock, cow etc.
It can be called imitation book cloth. Paper fabric is a strong paper made from chemical wood pulp highly sized and grained. It has high tensile strength but does not have resistant to water and stain. It is used in very cheap quality binding e.g. exercise note books.
Calico Cloth
It is as good as mull cloth but closely woven, lightly starched and is made from bleached cotton. It is superior to mull cloth and used like mull cloth but in superior quality books.
Cloth tape is used for sewing books. It may be 1.27cm in width and its length is according to the thickness of the book. Linen tape is very strong but at the same time nylon or terylene is the strongest.
A good hemp cord is used for sewing purpose. Usually 3 to 5 ply hemp cord is used for sewing. Nowadays nylon cords are also available. It is obtained in balls.
4. – Securing Materials – Thread, Wire, Metal and Plastic Units Thread
Sewing threads are manufactured from linen, cotton, nylon and terylene. Linen thread is expensive and most suitable for hand sewing.
Stitching wire is made from low grade medium carbon steel in various grades. It is usually coated to prevent corrosion. It is mostly round but flat wire is also used.
Eyelets made from brass, steel or aluminium is used to prevent the tearing of hole in a paper or board. Rivets are used extensively in fastening of metal parts in paper products. Various types of metal and plastic fasteners such as spiral, comb, inter screw, rings, metal backs etc are used to hold loose sheets together.
5. – Adhesives – Paste, Glue, Synthetic Adhesive, Hot-melt, Gum Paste
Paste is prepared from a mixture of plain flour, water, alum and formaldehyde. It is well mixed and heated on a pot until it is thickened. Formaldehyde is added as disinfectant. Paste is not water resistant, gets affected by humidity, bacteria, fungi and insects.
6. – Book Finishing Materials – Gold leaf, Blocking foil Gold Leaf
It is solid in books of 25 leaves, the size being about 31/2 inch. Square. Gold leaf sticks to anything upon contact, unless the article is dry, clean and absolutely free from grease.
The blocking foil is made of aluminium, silver, brass metallic powders spread over waxed cellulose or polyester film carriers. The powder is finally covered with thin layer of tan (powder from oak). The foils are used for hand tooling, and blocking.