General industrial paints

G.P.A. Turner , in Paint and Surface Coatings (Second Edition), 1999

12.4.5 Interiors of two-piece beer and beverage cans

The beer and beverage can is a form of food packaging, and must not add excessively to the cost of its contents. Can-makers are constantly seeking ways of making the package cheaper. Once the can was made in three pieces: the body (from a flat sheet) and two ends. Now most beer and beverage cans are two-piece cans. The body is produced from one piece of metal by a process known as drawing and wall ironing.

This method of construction allows much thinner metal to be used and the can has maximum strength only when filled with a carbonated beverage and sealed. Spin-necking saves metal by reducing the diameter of the neck. Between 1970 and 1990, beer and beverage containers became 25% lighter [16]. In the USA, where aluminium is cheaper, most beer and beverage cans are made from that metal. In Europe, tinplate is often cheaper, and many cans are made of this. Modern beer and beverage tinplate has a low tin content at the surface, the main functions of the tin being cosmetic and lubricating (in the drawing process). So a lacquer with excellent protective properties is required, to be used at minimum coat weight (6–12 µm, dependent on metal type).

Can-making is economical only if the cans can be made very quickly. Some 800–1000 cans a minute will be produced from one coating line, with bodies and ends coated separately. Bodies for beer and beverage cans are lacquered after being made and degreased. The rapid application is achieved by short bursts of airless spray from a lance positioned opposite the centre of the open end of the horizontal can. The lance may be static or may be inserted into the can and then removed. The can is held in a chuck and rotated rapidly during spraying to obtain the most uniform coating possible. Coating viscosities must be very low, and solids about 25–30%. The shape is relatively simple, but interiors are cured by convected hot air, in schedules around 3 min at 200 °C.

Carbonated soft drinks are acidic. Resistance to corrosion by such products is provided by coatings such as epoxy-amino resin or epoxy-phenolic resin systems. Beer is a less aggressive filling for the can, but its flavour may be spoilt so easily by iron pick-up from the can or by trace materials extracted from the lacquer, that it also requires similar high-quality interior lacquers.

The majority of these coatings have been successfully converted to water-borne colloidally dispersed or emulsion polymer systems, especially on the easier substrate to protect, aluminium. Water-based coatings have reduced overall costs and lowered the amount of solvent that has to be disposed of by after-burners to avoid pollution. Most successful systems are based on epoxy-acrylic copolymers with amino or phenolic crosslinkers.

There continues to be commercial interest in the electrodeposition of water-based lacquers in beer and beverage cans. Such a procedure avoids the need to apply in two coats, and is potentially capable of giving defect-free coatings resistant to the contents of the can at lower dry film weights. In water-borne spray coatings, solvent contents lower than 10–15% are being sought [17].

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Introduction to Active Food Packaging Technologies

Michael L. Rooney , in Plastic Films in Food Packaging, 2005

8.2.2 Process Engineering Limitations

Oxygen dissolved in beverages can be removed by vacuum treatments or nitrogen flushing. These processes do not always fit well with existing processing equipment due to frothing, so removal of oxygen by means of active packaging is an attractive option. Similar considerations apply to the flushing of small sachets containing low-density powders that are readily made airborne, thus interfering with sealing of the package. An additional characteristic of powders, when spray dried, is the occlusion of air within food particles. The release of this gas occurs slowly and is not achieved by means of evacuation on the processing line (King, 1955). The gas may be desorbed by equilibration with nitrogen over a period of days, but this is readily achieved by means of active packaging rather than by employing nitrogen-flushed holding tanks within the production line.

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Lightweight metal alloy tailor welded blanks

R. Padmanabhan , ... L.F. Menezes , in Tailor Welded Blanks for Advanced Manufacturing, 2011

5.1.1 Aluminum

Aluminum is available in abundance on the Earth's crust, largely in the form of cryolite or bauxite. Aluminum alloys are widely used in day-to-day life as thin foils in food packages and beverage cans, as structural members in public transport systems, aircraft parts, etc. This wide range of applications is possible due to properties such as superior corrosion resistance, natural and chemical inertness, recyclability and the ease with which a variety of parts can be produced. Aluminum also has high thermal and electrical conductivity, emissivity, strength-to-weight ratio, fracture toughness, energy absorption capacity, cryogenic toughness, fatigue strength, etc. It does not oxidize progressively because a hard, microscopic oxide coating forms on the surface and protects the metal from corrosive environments. With additional electro-coating, either anodic or cathodic, greater protection can be achieved in applications where the metal comes in direct contact with a corrosive environment. The strength of aluminum can be increased by alloying it with manganese, silicon, copper, magnesium, zinc, etc. Therefore aluminum grades are identified based on the alloying element and heat treatment, using a four digit representation, from 1XXX to 8XXX. The 1XXX series of aluminum has low yield strength while the 5XXX and 6XXX series have yield strengths equivalent to mild steel (Fig. 5.1a) and 7XXX series yield strengths are equivalent to high strength steels (AluMatter, 2010). Figure 5.1b shows the strengths of aluminum alloys of different grades. Cold working also enhances the strength of aluminum to approximately double. The main advantage of using aluminum is the ease with which it can be recycled to produce high quality parts (Abu-Farha and Khraisheh, 2008).

Figure 5.1. (a) Comparison of Al 5083-H34 and mild steel strengths; (b) aluminum alloy strengths according to different grades.

 (AluMatter, 2010)

Applications

The bodies of beverage cans are made of aluminum alloy (Al) 3004, while the ends are made of Al 5182, making it the largest volume alloy combination in the industry. Al 5454 has been widely used for rail car body construction for heavy load applications, and Al 5083/5383 has also been used in high speed single-hull ships, like the 'Proserio'. Al–Mg alloys such as Al 5454, Al 5086, Al 5083/5383 are used for the welded structures of offshore oil rigs and platforms applications to protect against high humidity and salt water exposure. In the automotive industries, Al 5754 has been used for body-in-white and Al 6111-T4 is used for external body panels. Al 7XXX series are used in guard rail and truck bumpers due to their toughness. Current applications of Al-tailor welded blanks (TWB) include body parts for high performance cars, such as Lamborghini Gallardo, and generally in the manufacture of bonnets, front door inners, rear rail inners, body side outers, etc. With recent advances in aluminum welding technologies, applications of Al-TWB are being extended to aircraft structures and body panels ( Schubert et al., 2001).

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FOOD AND NUTRITIONAL ANALYSIS | Alcoholic Beverages

J.F. Cacho , R. Lopez , in Encyclopedia of Analytical Science (Second Edition), 2005

Organic Acids

Organic acids in alcoholic beverages can be classified into volatile and fixed acids and may be of great importance. It has been found that some organic acids significantly influence the odor and taste of alcoholic beverages. Any substantial increase in the volatile acidity in wines seems to be a consequence of the activity of spoilage microorganisms. For this reason statutory restrictions exist in many countries for the maximum amounts of the volatile acids in wine.

Organic acids consist of aliphatic monobasic carboxylic acids from formic acid up to the C18 acids; aliphatic monobasic hydroxyl acids such as lactic acid; aldonic and uronic acids such as gluconic, glucuronic, and galacturonic acids; aliphatic monobasic oxo acids, mainly including succinic, malic, citric, and tartaric acids.

Distilled and undistilled beverages contain acetic acid in abundance. Frequently it amounts to 40–95% of the total volatile acids. Although the greatest part of the volatile acidity in wine consists of acetic acid, the remaining acids are nonetheless important aroma compounds. Many short-chain and long-chain acids, and in particular the branched-chain acids, have an appreciably strong odor.

Methods employed for the determination of organic acids in alcoholic beverages include titrimetric, colorimetric, enzymatic, paper chromatographic, thin-layer chromatographic, gas chromatographic, and liquid chromatographic procedures, as well as GC combined with MS. Titrimetric methods are mainly employed to determine the total volatile acids from formic acid up to C18 acids. In the procedure, the volatile acids are isolated from alcoholic beverages by steam distillation followed by titration with a strong base. In order to concentrate the volatile acids methods such as microdiffusion, reduced pressure, or vacuum steam distillation can be used.

Titrimetric methods have also commonly been proposed for the determination of fixed and total acids in wines. After treating the wine with a cation-exchange resin, oxalic acid can be precipitated as its calcium salt and titrated with potassium permanganate. For determination of tartaric acid in wine the acid can be precipitated as calcium tartrate or potassium hydrogentartrate.

Colorimetric methods are used for the determination of lactic and tartaric acids in wines. In the determination of lactic acid the procedure consists of the conversion of lactic acid into acetaldehyde by heating in the presence of sulfuric acid or by oxidation with cerium(IV) sulfate and subsequent formation of a colored compound with p-hydroxydiphenyl or piperidine and sodium nitroprusside. The red color formed is measured at 560–570   nm.

In the determination of tartaric acid in wines, the tartaric acid produces a colored complex with ammonium metavanadate, which is measured at 530   nm.

Major acids in distilled alcohol beverages are usually analyzed by high-performance liquid chromatography (HPLC). Several methods based on LC have been developed allowing simultaneous determination in alcoholic beverages of citric, tartaric, malic, succinic, lactic, and acetic acids in a single run using cation-exchange or C18 columns and refractive index, UV, or electrochemical detectors. If a previous step for cleaning or concentration is required, SPE based on a strong anion-exchange is the most selective technique for the enrichment of the ionizable acid analytes. It is preferred instead of the conventional solvent extraction method, which is time consuming and uses relatively large volumes of solvents.

Methods for the determination of organic acids by GC consist of direct and derivative techniques. The methods of extraction can take advantage of the acid properties of the acids by using an anion-exchange resin, or they can use a more unspecific strategy carrying out the extraction with an apolar solvent or resin. In the latter case, the pH of the beverage must be adjusted to 7 to assure complete recovery of the acids from the aqueous phase.

With modern capillary columns derivatization of low molecular weight acids is not compulsory and peaks without tailing can be obtained. In this case, it is important to keep a permanent check on the inertness of the whole GC system, because acids are very sensitive to active sites on the column. However, to analyze heavier and more polar acids by GC, derivatization must be applied. Derivative methods involve the isolation of the acids from the matrix and afterward the conversion of the acids into the more volatile benzyl or trimethylsilyl esters.

A recent alternative to HPLC or GC in the analysis of organic acids is capillary zone electrophoresis. It provides completely different selectivities from chromatographic methods, shorter analysis times, and no derivatization is required. As a drawback, the lack of UV absorbance of aliphatic organic acids above 220   nm requires the addition of substances showing strong UV absorption for indirect UV detection.

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Structures: Orientation Texture

S.I. Wright , R. Hielscher , in Reference Module in Materials Science and Materials Engineering, 2016

Rolled Sheet

One of the most studied materials using texture analysis is rolled aluminum sheet for beverage cans. The texture of this material must be as well controlled as possible in order to produce stock well suited for the deep drawing of cans. Typical (111) pole figures for rolled aluminum are shown in Figure 23.

Figure 23. Typical pole figures showing discrete orientations and calculated from harmonic coefficients for rolled aluminum.

The bulk of the orientations typically lie within a "fiber" in Euler space as shown in Figure 24. In order to simplify the analysis of rolled face-centered cubic materials such as aluminum, components associated with key locations along this fiber have been identified. These key components are shown in Euler space and in a (111) pole figure.

Figure 24. ODF and pole figures showing ideal components for face-centered cubic rolling textures.

A rolling texture can then be simply characterized by the intensities of these ideal components. This approach has been successfully used in the developing thermomechanical processes of rolled aluminum to achieve textures that optimize the deep-drawing performance of beverage can stock.

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SOLID-PHASE MICROEXTRACTION | Food Technology Applications

R. Marsili , in Encyclopedia of Separation Science, 2000

Introduction

The chemicals responsible for off-flavours, malodours and taints in foods and beverages can originate from incidental contamination from environmental (outside) sources (e.g. air, water, packaging material, a contaminated ingredient) and from chemical reactions occurring within the food material itself (e.g. lipid oxidation, enzymatic action, microbial metabolic reactions). In addition, imbalance off-flavours can occur when certain ingredient components that are normally present and often essential to the product are present in abnormally high or low concentrations.

When significant off-flavour problems occur, one of the first priorities of the food chemist is to identify any volatile or semivolatile organic chemicals that may be responsible. Once the identity of the off-flavour chemical(s) has been established, it is possible to speculate on its mechanism of formation and then decide on what corrective actions to implement to eliminate recurrence of the problem in the future.

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Production of secondary aluminium

G. Wallace , in Fundamentals of Aluminium Metallurgy, 2011

Taldon – baled aluminium UBC scrap

Shall have a minimum density of 14 pounds per cubic foot (225   kg/m3 for unflattened UBC and 22 pounds per cubic foot (353   kg/m3) for flattened UBC. Size: Minimum 30 cubic feet (.85   m3) with bale range dimensions of 24″to 40″(61 to 100   cm) by 30″to 52″(76 to 132   cm) by 40″to 84″(102 to 213   cm). The only acceptable tying method shall be as follows: four to six 5/8″(1.6   cm) × .020″(5   cm) steel bands, or six to ten #13 gauge steel wires (aluminium bands or wires are acceptable in equivalent strength and number). Use of skids and/or support sheets of any material is not acceptable. Must be magnetically separated material and free of steel, lead, bottle caps, plastic cans and other plastic, glass, wood, dirt, grease, trash and other foreign substances. Any free lead is basis for rejection. Any and all aluminium items, other than UBCs are not acceptable. Baled aluminium UBC (Taldon) is shown in Fig. 4.6.

4.6. Taldon.

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Corrosion and corrosion protection of aluminium

N. Birbilis , B. Hinton , in Fundamentals of Aluminium Metallurgy, 2011

19.1 Introduction

From a corrosion perspective, aluminium has been a successful metal, finding applications ranging from household foil and beverage cans to essential construction material for aircraft and space vehicles. Transportation, largely aerospace applications, has provided the greatest stimulus for both alloy development and corrosion research that continues today ( Polmear, 1995).

As covered in prior chapters, aluminium and its alloys offer a diverse range of desirable properties that can be matched closely to the demands of each application by the appropriate choice of composition, temper, fabrication and processing mode (Davies, 1999).

In the past half century, the major topics for corrosion research in relation to aluminium alloys have included localised corrosion of aluminium alloys containing magnesium, the stress corrosion cracking of alloys used in aerospace applications, galvanic corrosion of aluminium in atmospheric and automotive applications, corrosion inhibition and most recently the filiform corrosion of aluminium sheet. Some of the present aluminium corrosion challenges are the ramifications from the elimination of chromates as inhibitors in protection schemes, the tolerance of higher impurity levels due to the increased use of recycled metal, the integration of lithium into alloys while retaining corrosion resistance and the sensitisation of non-heat treatable aluminium-alloys.

This chapter will address the issues related to various forms of corrosion of aluminium and its alloys. Additionally, some attention will be given to corrosion protection strategies currently in use. In an approach unique to this chapter compared to typical corrosion publications, this chapter will culminate in a case study. The study will focus on an aerospace application, which includes many of the principal forms of aluminium alloy corrosion. Additionally, the aspects of corrosion in service, which is very often associated with occluded and local micro-environments, are emphasised.

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Evaluation of Corrosion

Branko N. Popov , in Corrosion Engineering, 2015

1.7.5 Filiform corrosion

Filiform corrosion is observed under thin organic coatings on aluminum, steel, aircraft structures exposed to humid atmosphere, beverage cans, flanges, gaskets, dis-bonded underlying metals coated with organic coatings weld zones, and so forth. Corrosion-resistant alloys of stainless steel, copper, and titanium are not susceptible to filiform corrosion. Figure 1.12 shows filiform corrosion of steel substrates painted with clear acryl paint [38]. Filiform corrosion was induced by knife-scored specimens exposed to 5% NaCl and humidity (40% and 80% RH). The corrosion of the underlying metal was clearly observed through the clear paint surface. The line in the center represents the knife-score. The filiform corrosion grew in both directions from the line and is composed of a head and the tail. The head and the tail are filled with a FeCl2 solution and corrosion products, respectively [39].

Fig. 1.12. Appearance of filiform corrosion tracks [38].

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Reproductive and Endocrine Toxicology

R.A. Nowak , ... S.A. Machado , in Comprehensive Toxicology, 2010

11.26.3.2 Bisphenol A

BPA is an organic compound that is widely used in the manufacture of polycarbonate plastics and epoxy resins. This chemical can leach from food and beverage cans as well as dental sealants and composites ( Biles et al. 1997; Brotons et al. 1995; Olea et al. 1996), making it a major xenoestrogen pollutant of the environment (Kawagoshi et al. 2003; Richter et al. 2007; Staples et al. 1998) and human health (Maffini et al. 2006) ( Figure 2 ). Animal studies using neonatal mice injected with BPA showed that these mice developed extensive uterine pathologies including adenomyosis, leiomyomas, atypical hyperplasia, and stromal polyps (Richter et al. 2007). In contrast, prenatal exposure to BPA did not seem to be a causative factor for induction of uterine tumorigenesis (Markey et al. 2005; Suzuki et al. 2002; Yoshida et al. 2004). Markey et al. (2005) reported that treatment of pregnant mice with BPA for 14 days beginning at day 5 of gestation caused a decrease in the volume of the endometrial lamina propria and increased the expression of ER and progesterone receptor (PR) in the luminal epithelium and subepithelial stroma of the endometrium with no indication of uterine tumors in the 3-month-old offspring. This lack of uterine tumorigenesis after prenatal exposure to BPA is rather unexpected considering the estrogenic activity of BPA and the induction of uterine cancers by DES in mice (Keri et al. 2007). Furthermore, in a study by Huff (2001), treatment of Fisher rats with 1000 or 2000   ppm BPA actually decreased the rate of endometrial stromal polyps as compared to controls. Although this result was correlated with a decrease in body weight, no specific explanation or mechanism was discussed.

Figure 2. A summary of the effects of prenatal exposure to bisphenol A on various components of the reproductive axis. Reproduced with permission from Maffini, M. V.; Rubin, B. S.; Sonnenschein, C.; Soto, A. M. Mol. Cell. Endocrinol. 2006, 254–255, 179–186.

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