All About Canning

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CANNING

Cans and their Manufacture

M.de F. Filipe PocË as, Ecola Superior de

Biotechnologia, Universidade Catolica Portuguesa,

Portugal

Copyright 2003, Elsevier Science Ltd. All Rights Reserved.

doi:10.1006/rwfn.2003.0160

Filipe PocË as, M de F

Ecola Superior de Biotechnologia,

Universidade Catolica Portuguesa,

ServicË os de Embalagem (Packaging Services),

Rua Dr. Anto Â nio Bernardino de Almeida,

Portugal

Cans0001 Cans for food and drinks may be manufactured in tin

plate, tin-free steel, or aluminium. Depending on themetal to be used and on the type of can, differentproduction methods may also be used to manufacturecans. The characteristics of the metals and the oper-ations to produce and close the cans are describedbelow. Additionally, information is given on the poly-meric coatings used to avoid undesirable interactionsbetween the product and the metal surface.

Types of Cans for Foods and Drinks0002 Metal cans for foods and drinks are usually classified

in three-piece cans and two-piece cans. The can com-ponents and the terms commonly used to designatedifferent parts of a can are shown in Figure 1. Cans inthe first group are composed of a welded body andtwo seamed ends and are usually made in tinplate.The two-piece cans have the body and the bottom endin a single piece and a seamed top end. They are madein tinplate, aluminum, or tin-free steel, and are pro-duced by the Draw±Redraw (DRD) process or by theDraw-Wall-Ironing (DWI) process. The DRD processis used to produce shallow cans, with a height/diam-eter ratio, low in whereas the DWI process is typicallyused for drink cans, commonly with a high height/ diameter ratio. These cans have a very thin wall, thuslacking mechanical resistance. They are used for car-bonated drinks where the high pressure from theproduct (very often around 4 atm) imparts the re-quired resistance. In still drinks, the application of liquid nitrogen in the headspace yields a high internalpressure.

0003 A wide variety of can shapes are available: round,

rectangular, oval, trapezoidal, etc. The circular can is

the most popular shape because it is the easiest shapeto seam and uses the least metal sheet area for a givenvolume content. Rectangular shapes are common forprocessed fish because this format benefits the prod-

uct presentation when the consumer opens the can.00For a given can capacity, the surface area of metal

required for round cans is minimal when the candiameter equals its height. The dimensions of cansare designed, taking into consideration this diam-eter/height ratio so as to maximize the efficiency of metal usage. However, it is easier and less expensiveto reset a production line to make a can with a differ-ent height than to change its diameter, and thusa standard can diameter system was developed(Table 1 shows the standard diameters of roundcans in both imperial and metric units). Therefore

certain can dimensions have been commonly usedfor certain capacities of cans. The nominal size of round cans is given as diameter Â height. The dimen-sions of rectangular cans are given as three sets of numbers: the first two sets are base dimensions, andthe third is the height dimension. The units conven-tionally used are millimeters for metric units; imperialdimensions are given in three digits: the fist digit is inwhole inches, and the second two digits indicate16ths of an inch. For example, a can designated as307Â403, is 3±7/16 inches in diameter and 4±3/16inches in height. Table 2 shows some of the morewidely used cans for foods.

Metallic Materials

00Tinplate is the material used more widely in cans forfoods. The term tinplate refers to a low-carbon mildsteel sheet with a coating of tin on each surface of thematerial (Figure 2a). The steel varies from around0.12 to 0.5 mm in thickness. The thickness and hard-ness of the tinplate are selected as a function of thecan size and format, as well as taking into consider-ation the mechanical solicitations during the thermalprocessing and handling. In general, the smaller thediameter of the can, the thinner the body wall andends may be to withstand the imposed loads. Largercans with thinner walls may be used if wall beading isprovided. Double-reduced steel (steel that has under-gone a second cold reduction before tinplating) alsoenables downgauging with no loss of performance.This steel has additional strength, but is less ductilecompared with the single reduced plate, which mayimpose some limitations to the can-manufacturingprocess.

Galley: Article No. 0160

CANNING/Cans and their Manufacture 1



0006 The tin coating is applied in weights from 1.0 to11.2gmÀ2, with the same or different amounts of tin on each surface. Differentially coated tinplate isidentified by marking a set of parallel lines, the linepattern being related to the differential weight com-bination. Normally, the pattern is applied on themore heavily coated surface, inside the can, where

greater protection is needed. Figure 3 shows the tincoating weights used and, in the case of differentiallycoated steel, the pattern of marking lines.

0007 The steel strip usually has a passivation treatmentto render its surface more stable and resistant to theatmosphere, as well as to improve lacquer adhesion.Passivation treatment results in the formation of a toplayer of chromium and chromium oxides and tinoxides. After the passivation, the plate is given alight oiling to help preserve it from attack and toassist the passage of sheets through container-formingmachines without damaging the soft tin layer.

0008 Tin-free steel (TFS) or electrolytic chromium-coated steel (ECCS) is low-carbon steel coated withmetallic chromium and chromium oxides with aweight of around 80 and 20mg mÀ2, respectively(Figure 2b). The surface of TFS has a better adhesionto protective lacquer coatings or printing inks andvarnishes than tinplate. It requires shorter times incuring enamels (since higher temperatures may beused, due to the lack of a low-melting-point tinlayer) but is less resistant to corrosion than tinplate.TFS is not used in three-piece cans, because it cannotbe soldered by traditional techniques, nor in DWItwo-piece cans because its hard and rough surfacemakes drawing operations in uncoated metal imprac-ticable. Therefore, TFS is frequently used for can endsand DRD two-piece cans.

0009 Aluminum is a light metal, easy to work through-out most of the conventional can-forming processes.Aluminum is used for two-piece containers only, DWIand singly or multiply drawn cans, but it is alsoformed into easy-open ends. Aluminum cans mayalso be formed by impact extrusion, this type of cannormally being used for monobloc aerosols.

0010 Aluminum body stock is available in a range of thicknesses from 0.25 to 0.30 mm, whereas endstock covers the range from 0.30 to 0.38 mm. Mostcommercial applications of aluminum require specialproperties that the pure metal cannot provide. There-fore, alloying agents are added to impart strength,improve formability, and influence corrosion charac-teristics. A wide range of alloys are commerciallyavailable for packaging applications, depending onthe container design and fabrication method beingused. The alloys are identified by four-digit numberswhere the value of the first digit indicates the alloy

type and the principal alloying ingredient. For

example: 2xxx for copper, 3xxx for manganese,4xxx for silicon, and 5xxx for magnesium. Series1xxx represents aluminum with 99.00% or higherpurity. Commercially pure aluminum (types 1100and 1050) is used for the manufacture of foil andextruded containers since it is the least susceptible towork hardening. For rigid packaging, the alloy elem-

ents used are manganese and magnesium (alloy types3004 and 5184). When the aluminum surface is ex-posed to the atmosphere, a layer of aluminum oxidesis naturally formed, which protects the metal fromfurther oxidation. This self-protecting characteristicgives the aluminum its high resistance to corrosion,unless it is exposed to some substance that destroysthis passivation layer. Aluminum will corrode on con-tact with products with a pH lower than 4 or higherthan 9, and when used for manufacturing cans forfood and beverage products, it is always coated with aorganic lacquer in the internal surface.

Manufacturing Processes

Steel and aluminum are initially in coil form, so sheetcutting is often the first manufacturing process. Thisoperation can be performed by the can-maker if coilcut-up lines are available in the plant. Otherwise,material must be acquired already in sheet form.Sheets to be used for the production of can ends orround DRD cans are scroll-cut (Figure 4). This is amethod used to cut coil into sheets in a pattern, whichreduces metal wastage. It enables circular blanks tobe packaged more densely: skeleton scrap is reducedby a third compared with straight-cut sheet.

Three-piece Cans

Starting with metal sheets, rectangular in format andwith dimensions suiting the can body size (Figure 5a),the sheets are coated on the side that will become theinternal surfaces of the finished cans (Figure 5b). Thisspecial lacquer protects the can itself from corrosionand limits the interaction between the contents andthe metal. However, welding margins should be left

uncoated since the polymeric nature of the lacquerwould influence the electric current passage throughthe metal (see details below). The lacquer is cured assheets pass in an oven (Figure 5c). The sheet may alsobe printed for decoration on the other side, unless apaper label is to be used.

The sheets are fed into a slitter, where they are cutinto body can blanks (Figure 5d). The blank is thenfed to the forming rolls, which generate a cylinderwith the edges of the side seam (Figure 5e). Thecylinder edges are welded by squeezing them togetherwhilst passing an electric current through them


2 CANNING/Cans and their Manufacture



(Figure 5f ). This heats up the metal sufficiently for asound join to be made. To protect the weld seam, acoating is applied immediately after the can bodyexits the welder, in both sides of the side seam(Figure 5g). Powder coating is usually applied electro-statically to the interior of the side seam.

0014 The cans are passed through a flanger, where the

top and bottom of the can are flanged outwards toaccept the ends (Figure 5h). Ends, produced else-where, are seamed to the can bodies to close oneend (called the `maker's end') of every can (Figure 5i).

0015 Depending on the can design, cans are passedthrough a beader, where the walls of the cans havecircumferential beads formed (Figure 5j). Beading of the can body wall, although reducing the top-loadresistance of the can, allows for a reduction in wallthickness without sacrificing paneling performance.

0016 Testing is performed with high-pressure air todetect pinholes and poor seams on every can, and

the finished can bodies are then transferred to thewarehouse to be automatically palletized before de-livery to the filling plant.

DWI Two-piece Cans

0017 Aluminum or steel coil (Figure 6a) is lubricated with athin film of oil and then fed continuously through acupping press (Figure 6b), which stamps and drawsdisks into cups at a rate of more than 1500 cans perminute. Each cup is rammed through a series of tung-sten carbide rings for drawing and ironing. This pro-cess redraws the cup to smaller diameter and thins thewalls, whilst increasing the height leading to un-trimmed cans (Figure 6c).

0018 Trimmers remove the surplus irregular edge andcut each can to a precise specified height (Figure 6d).The trimmed can bodies are passed through washers(Figure 6e) for removal of all traces of lubricantand then dried in preparation for internal and exter-nal coatings. The clean cans are coated externally(Figure 6f ) with a clear or pigmented base coat,which forms a good surface for the printing inks.The cans pass through a hot air oven to dry the

lacquer (Figure 6g).0019 The next step is the application of the print design

in up to six colors, and a varnish, by a highly sophis-ticated printer/decorator (Figure 6h). A coat of var-nish is also applied to the base of each can by the rimcoater (Figure 6i). The cans pass through a secondoven, which dries the ink and the varnish. Spraymachines apply an internal coating of protectivelacquer (Figure 6j) to maintain product quality, andthe cans are then dried in the final oven (Figure 6k).

0020 The cans are passed through a necker/flanger(Figure 6l), where the diameter of the body is reduced

(necked in), and the tops of the cans are flangedoutwards to accept the ends after the cans have beenfilled.

00Every can is tested at each stage of manufacture. Atthe final stage, they pass through a light tester, whichautomatically rejects any can with pinholes or frac-tures (Figure 6m). Cans are then moved to the ware-

house for palletizing and delivery to the filling planttogether with the ends.

DRD Two-piece Cans

00This process is similar to the DWI process, except thatthe final height and diameter of the container areproduced by sequentially drawing cups to a smallerdiameter, i.e., causing metal to flow from the base tothe wall of the container rather than ironing the con-tainer wall. The wall and base thickness of DRD cans,as well as the surface area, are identical to the originalblank, as opposed to the DWI cans, where the wallthickness is much lower than the base thickness(Figure 7).

00The process starts with blanking and cupping, inwhich cups are produced from prescrolled sheets,lacquered, and/or decorated. The cups then gothrough the first drawing operation, where they aredrawn by a punch through a die. The cups producedat this stage may undergo a similar redraw process forfurther diameter reduction as the height is progres-sively increased (Figure 7b).

00There is a linear relationship between the max-imum height to which a container can be drawn in asingle operation and its diameter. The taller the can,the more drawing operations are required. Also,single-reduced steels can be drawn more thandouble-reduced, which can be used in lower gaugesfor the same strength.

00The bottom end is the thickest region and governsthe material gauge, often resulting in an excessive sidewall thickness. Typically, 0.2-mm-thickness prelac-quered tinplate and TFS is used for the DRD process.DRD cans are currently used in the packaging forfood rather than beverages, where a greater wall

thickness is required to withstand pressure reversals.The body is beaded, and TFS is used more than tin-plate because a better enamel adhesion is achievedwith the former.

Ends

00The can end is designed for optimum deformationbehavior during the food-heating process thereby pre-venting permanent distortion: it should resist the highrelative internal pressure achieved in the heating pro-cess that tends to deform the can ends outwards, andit must also be sufficiently flexible to return to its





original profile as the internal pressure becomesslightly negative inside the processed can. This behav-ior depends on the metal thickness, the profile of the expansion rings, and the countersink depth(Figure 8).

0027 The scroll-cut sheet, previously lacquered, is fedthrough a press that stamps the ends. After stamping,

the edges are curled and passed through a liningmachine, which applies a precise amount of a sealantcompound around the inside of the curl. This sealantassists the formation of a hermetic seal by providing agasket between adjacent layers of metal in the doubleseam.

0028 Easy-open ends are produced, from a previouslystamped shell (Figure 9a), in a press comprising fourbasic operations: a bubble-like structure is drawn(Figure 9b), a cylindrical button is drawn fromthe bubble (Figure 9c), the score line is performed(Figure 9d), and the tab is attached at the rivet station

by compression of the button, the tab being formedon a separate operation (Figure 9e). In this way, thetab is affixed to the end without any loss of endintegrity. Figure 9 illustrates the basic operations.

Double seaming

0029 The end is joined to the can body by a double-seamingoperation that is carried out in two stages (Figure 10):in the first operation, the end curl and the body flangeare brought together and rolled inwards so that theend hook is well tucked up underneath the bodyhook. The shape of the seaming roll determines thecontour of the seam at the end of this stage; in thesecond operation, the seam is tightened by a secondset of seaming rolls. The final quality of the doubleseam is defined by its length, thickness, and the extentof the overlap of the end hook with the body hook(Figure 11). Rigid standards are laid down for anacceptable degree of overlap and seam tightness.

Welding Side Seams of Three-piece Cans

0030 The side seam is made by a resistance-welding pro-cess, using the lost-wire-electrode principle. After the

can body blank has been formed into a cylinder overthe welding arm, the overlapping seam (0.4 mm formost cans) passes between two copper weld roolswhere the weld is formed (Figure 12).

0031 The two layers in the seam are squeezed togetherbetween the upper weld roll located outside the canbody and a smaller-diameter inner weld roll. An al-ternating current is passed to the upper roll, and highelectrical resistance causes the interface temperatureto rise rapidly to at least 900 C, resulting in solid-phase bonding. As the can body moves continuouslybetween the two weld rolls, a spot weld is created at

each peak of the alternating current. By adjusting thefrequency of the current to the linear speed of the canbody, the correct number of spot welds per unit of canlength can be achieved. In a good weld, the individualspots should merge into a continuous weld. Althoughthe welded seam is free from the danger of lead pick-up, the weld has to be effectively coated to prevent

any traces of iron being picked up by some types of beverages and acidic foods. The external side of theseam is also coated for protection.

Protective Organic Coatings

The primary function of interior can coatings,enamels or lacquers, is to prevent any interactionbetween the can and its contents, although someenamels have special properties, and others are usedmerely to improve the appearance of the pack. Exter-ior can coatings may be used to provide protection

against the environment, as well as for decoration andproduct labeling.

Internal lacquers must be inert, must provide agood barrier, and must also have a good mechanicalresistance, as well as thermal resistance if the productis to be thermally processed. The lacquer mustcomply with the regulations for materials intendedfor food contact, i.e., only approved substances thathad sustained successful migration or extraction testsand that do not impart any flavor to the contents,may be used.

The barrier provided by the lacquer depends on itschemical composition and on its porosity (whichmust be as low as possible) and which in turn dependson the thickness of the lacquer. Control of the amountof lacquer applied, usually measured in terms of themass of dry film per area of metal sheet, is veryimportant since a thin layer will not cover the surfacecompletely, and a layer that is too thick will lead tobrittleness, lack of flexibility, and poor adhesion, aswell as being uneconomical.

The lacquer must resist mechanical solicitationsduring can and ends manufacturing operations, as inthe case of three-piece cans and most DRD two-piececans that are produced from a precoated metal sheet.Flexibility and adhesion are also important character-istics of lacquers, as during retorting, the can tends todeform, due to a pressure imbalance.

The lacquer is usually applied by roller coating tothe metal in the flat form sheet or coil before fabrica-tion. Spraying is used for coating the internal surfaceof DWI two-piece cans that cannot be produced fromprelacquered sheets, owing to the considerableamount of metal deformation and surface disruptionoccurring during ironing operations. Powder coating,

where the resin is applied dry in the form of a fine





powder, usually under the direction of an electrostaticfield, is used for the protection of welded side seams(internal side), where heavy coatings are required.A postfabrication repair lacquering is applied tocans used to pack products with very stringent pro-tection requirements, to compensate for natural ap-plication imperfections and layer damage during can

fabrication.0037 After application, the lacquer must be dried by

solvent removal, oxidation, and/or heat polymeriza-tion. This process is usually performed in a forcedconvection oven using hot air up to 210 C for up to15 min. Recent developments include resin formula-tions, which need lower temperatures and shortercuring times, often through the use of ultravioletradiation (these ultraviolet-curing resins are virtuallysolvent-free).

0038 The more common chemical families of protectivelacquers are the phenols, epoxy, polyesters, and vinyl.

The resins are rarely used pure. They are modifiedand/or combined with other resins and additives thatconfer specific characteristics. Table 3 summarizesthe major lacquers' characteristics and applications.

0039 Phenolic resins are produced by the action of for-maldehyde on phenol and are characterized by havinga high degree of reticulation enhancing barrier, hard-ness and chemical inertia, but limited flexibility dueto the presence of the bulge phenolic ring.

0040 Epoxy resins are produced by polymerization of bisphenol A with glycerol epichlorohydrine. Epoxyis highly reactive, allowing for combination withother resins, and it has a good chemical resistance. Itis very flexible because of its linear structure, withoutreticulation, and it is often combined with phenolicsgiving the epoxy-phenolic family, one of the mostwidely used families of resins for lacquering. Athree-dimensional structure is formed during curing,either by straight blending of a solid epoxy resin witha solid phenolic resin or by condensation of a mixtureof two resins in appropriate solvents. Epoxy-phenoliclacquer combines the good adhesion properties of theepoxy resin with the high chemical resistance proper-ties of the phenolic resin. The balanced properties of epoxy-phenolic coatings have made their use almostuniversal in food-can applications. Epoxy may alsobe combined with amines to produce epoxy-urea andwith fatty acids to produce epoxy-esters.

0041 Vinyl coatings are based on copolymers of vinylchloride and vinyl acetate. They can be used with orwithout pigmentation, and they can be blended withalkyd, epoxy, and phenolic resins to enhance theirperformance. Their main disadvantage is the highsensitivity to heat and retorting processes, restrictingtheir application to cans that are hot-filled and to beer

and beverage products.

00Vinyl organosol coatings are dispersions of PVC(homopolymer), sometimes reinforced with solublethermosetting resins, such as epoxy or phenolic, toenhance thermal resistance and adhesion. Plasticizersare also added to aid film formation. These coatingsare typically white due to the addition of titaniumdioxide.

00Polyesters have an excellent resistance to high tem-peratures and are often used for can external coating.When used for heat-processed foods, they are modi-fied with phenolic resins and often white pigmentedwith titanium dioxide.

00The choice of lacquer depends on the nature of thefood and the can to be used. Products that containsulfur-containing amino acids require sulfur-resistantlacquers to prevent staining of tinplate surfaces.Sulfur compounds may break down during heat pro-cessing to release sulfides, which react with tin toform brown±violet tin sulfide (SnS) that affects the

global can surface or with iron to form iron sulfide(FeS) in spots where, due to lacquering and tin-coating imperfections, iron may be in contact withthe food. These compounds do not affect the productsafety or quality but are suspicious to the consumer.To overcome this problem, lacquers offering a goodphysical barrier, such as phenolic or epoxy-phenolic,are used. In addition, these are pigmented with zincoxide, which reacts preferentially with the sulfurcompounds, thus acting as chemical barriers.Lacquers may also be pigmented with aluminiumpowder or white pigments, to obscure any tin sulfidethat might be formed.

00Acidic foods require a very good protection toprevent can corrosion. A vinyl organosol with a highthickness, pigmented with aluminium powder ortitanium dioxide, or a double coating of epoxy-phenolic plus vinyl organosol may be used for thispurpose.

00Beer and other drinks susceptible to flavor contam-ination by metallic traces require very good protec-tion as well. DWI cans are coated after fabrication,usually with two coats of lacquer: epoxy-phenolicplus vinyl, epoxy-urea plus vinyl or a double layerof epoxy-urea.

See also: (0089a) ; (0159a) Canning: Principles; (0162a)

Food Handling; (0163a) Quality Changes During Canning;

(0872a) Packaging: Packaging of Liquids; (0873a)

Packaging of Solids

Further Reading

Bakker M and Eckroth D (1986) The Wiley Encyclopaediaof Packaging Technology. New York: John Wiley.





Robertson GL (1993) Food Packaging Principles and Prac-tice. New York: Marcel Dekker.

Soroka W (1995) Fundamentals of Packaging Technology.Herndon, VA: Institute of Packaging Professionals.

Can body

Beading

Side-seam

Double-seam

Easy-openend

fig0001 Figure 1 Can terminology.

AluminumTin-free steelTin plate

Lacquer

Lacquer

Lacquer

Passivation

Tin

Alloy tin/iron

Steel

Chromium oxide

Chromium

Steel

Aluminum oxide

Aluminum alloy

fig0002 Figure 2 Metallic materials for can-making.





Differential coating (identification on heavier coated side)

D 8.4/5.6

D 11.2/5.6

D 2.8/1.1 [mm]

D 5.6/2.8

D 11.2/2.8

D 8.4/2.8

25.4

38.0

38.0 12.7

50.8

38.0

25.4

12.7

Equal coating

E 2.8/2.8

E 5.6/5.6

E 8.4/8.4

E 11.2/11.2

ig0003 Figure 3 Tin coating weights.

Scroll-cut sheet

Straight-cut sheet

Width across coil

Width across coil

Lengthof cutsheet

Length

of cutsheet

(b)

(a)

ig0004

Figure 4 Comparison between scroll and straight cut sheet.





(a) (b) (c) (d) (e)

(f) (g) (h) (i) (j)

fig0005 Figure 5 Three-piece can-manufacturing process.

(a) (b) (c) (d)

(e) (f) (g) (h)

(i) (j) (k) (l)

(m) (n) (o) (p)

fig0006 Figure 6 Two-piece DWI can-manufacturing process.





(a)

(b)

ig0007 Figure 7 Comparison between (a) DRD and (b) DWI processes.

From Bakker M and Eckroth D (1986) The Wiley Encyclopaedia of

PackagingTechnology. New York: John Wiley with permission.

Seaming panel

Bead

Second expansionpanel

Center panel

First expansionpanal

figFigure 8 Can end profile.

(a)

(b)

(c)

(d)

(e)

Sealant

Score line

Rivet

Ring tab

ig0009 Figure 9 Easy-open end production.

Lining compound

Can end

Flange on can body

(a)

(c) Profile of roller die

Lining compound

Liningcompound

Liningcompound

Profile of roller die

Former

(d)

(b)

figFigure 10 Double-seaming: (a)and (b) first seaming operation;

(c) and (d) second seaming operation.





S e a m l e

n g t h

E n d - h o o k l e g t h

O v e r l a p

Seam thickness

C o u n t e r s i n k d e p t h

B o d y - h o o k

l e n g t h

Body-plate thickness

End-platethickness

fig0011 Figure 11 Main components of a double seam.

1 2

5

3

3 3

3

fig0012 Figure 12 Welding side seam of a three-piece can: 1, blank feed; 2, wire fed; 3, welding rolls (electrodes); 4, copper wire (welding

contact); 5, used wire. From Bakker M and Eckroth D (1986) TheWileyEncyclopaediaof PackagingTechnology. New York: John Wiley, with

permission.

tbl0001 Table 1 Nominal diameters of round cans

Imperial units Metric units

202 52

211 65

300 73

307 83

401 99

404 105

502 127

603 153

610 168

700 176

Table 2 Examples of common sizes of food cans

Type Capacity (ml) Dimensions (mm)

Round three-piece cans 142 55 Â 67

212 65 Â 71

212 73 Â 58

236 65 Â 78

335 73 Â 88

340 99 Â 52

350 83.7 Â 69

425 73 Â 109

850 99 Â 118

945 99 Â 123

Rectangular two-piece cans 75 104 Â 59 Â 19

125 104 Â 59 Â 28

150 154 Â 55 Â 23

250 105 Â 76 Â 38





bl0003 Table 3 Application and characteristics of lacquers

Family Application Flexibility Adhesion Resistance to

heat-processing

Phenolic Fruits, vegetables, meat: very good barrier Bad Bad Very good

Epoxy-phenolic Wide use, can be pigmented with Al, ZnO; characteristics

depending on formulation

Good Good Good

Vinylics Beverages Excellent Good Bad

Organosols Large use in two-piece cans Very good Very good GoodAcrylics Pigmented with TiO2 Good Very good Medium

Epoxy-urea Beverages Good Good Medium

Pol yesters Pigmented with TiO2 Medium Good Good





Manuscript Queries

TITLE: ENCYCLOPEDIA OF FOOD SCIENCES AND NUTRITION Manuscript code: 0160Entry: Cans and Their ManufactureArticle: Author: Filipe PocasSheet _1__ of _1__

Page Para/line Query

Figures 7 and 12: Has permission been obtained?

1 Please clarify town/city in shortened and full addresses

10 5/1 “mechanical solicitation” – Do you mean “damage” or …?

11 5 Sentence “Phenolic resins” does not make sense. Please check

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