Tinplate containers

A tinplate container has an energy advantage over some of the competitive container materials, as shown in Table 6. By virtue of its magnetic properties, tinplated material is more readily separated by other forms of industrial or domestic waste. 

Tinplate containers The behaviour of tinplate is basically similar to that of other types of tinned steel, but performance requirements of tinplate containers are special. Containers are used in several forms ... 

Tinplate Containers for Packaging Irradiation-Sterilized Foods... 

A screening study for evaluating and selecting components of the tinplate container—tinplate, enamel, end-sealing compound, and side-seam solder—which were irradiated at designated doses and temperatures... 

Tinplate and Solder. Metallurgical studies were performed to determine the effect of irradiation at low temperature on the corrosion resistance of tinplate and on the mechanical properties and microstructure of tinplate and side-seam solder of the tinplate container. The area of major interest was the effect of low-temperature irradiation on the possible conversion of the tin from the beta form to the alpha form. In the case of pure tin, the transition occurs at 18 °C. It was feared that low-temperature irradiation would create dislocations in the crystal lattice of tin and enhance the conversion of tin from the silvery form to a powdery form rendering the tin coating ineffective in protecting the base steel. Tin used for industrial consumption contains trace amounts of soluble impurities of lead and antimony to retard this conversion for several years. 

Table VII shows the data on the effect of the low-temperature irradiation on the tensile properties of cast 98-2 solder (98% lead-2% tin). These data indicate that the radiation had no effect on the tensile properties of the commercial solder which is used for the side seam of tinplate containers. Metallographic examination confirmed the absence of change in the microstructure of the solder after irradiation. (Figure 2).

Production Test. In a small-scale production test, tinplate containers with two commercially available enamels and two end-sealing compounds, which were selected from the results of this study, performed satisfactorily when packed with beef and ham. Beef was irradiated with 4.5-5.6 Mrad at 5, —30, and —90°C ham was irradiated with 3-4 Mrad and 6-7.5 Mrad at —30°C. For this production test, beef and ham were packaged in round tinplate containers and ham in Pullman tinplate containers, frozen and refrigerated products were shipped 1,200 miles by truck, and were gamma irradiated at various doses and temperatures. Irradiated products were shipped 1,200 miles in a non-refrigerated truck and stored at selected temperatures and humidities. The integrity of the cans was evaluated after storage for 10 days, 3 months, and 6 months. 

The production test showed that the epoxy phenolic enamel was the preferred enamel for coating tinplate containers used in packaging irradiation-sterilized ham and beef. The preferred end-sealing compound for the same application was the blend of cured and uncured isobutylene-isoprene copolymer. 

The evaluation of the components of the tinplate container showed that the preferred enamel for irradiation processing was the epoxy phenolic the preferred end-sealing compound was the blend of cured and uncured isobutylene—isoprene copolymer. Component testing of tinplate and solder for possible changes in mechanical properties, microstructure, and corrosion resistance indicated that the radiation caused... 

Within the past three decades tin-free steel (TFS) has been developed. This material consists of a mild steel base—exactly as used for tinplate—but with a coating of chromium-chromium oxide only about 1/30 as thick as an average tinplate coating. The function of this coating is merely to protect the steel base from corrosion prior to fabrication. TFS containers need to be coated on the inside and outside with one of many organic coatings in order to make them at least as corrosion-resistant as uncoated tinplate containers. To date the main usage of TFS has been for can ends. 

Figure 10.5 Typical metal joints used in tinplate containers...

The built-up tinplate container is the cheapest form of aerosol but was initially considered unacceptable for most pharmaceutical products due to the unsightly appearance of the soldered side seam. However, the development of reduced width side seams by jet soldering, cementing or welding e.g. soudronic weld, makes the built-up container a more attractive proposition. Most of the built-up aerosol containers produced in the UK nowadays have welded side seams. Alternatively the side seam can be concealed by applying a printed wrap-around label to the finished aerosol. 

In the flat as sheets or reels, e.g. paper, board, tinplate, films, foils and laminates. Materials in both sheet and reel forms may be further processed to give packs which may remain in the flat (e.g. collapsible cartons) until erected or are directly fabricated into a three-dimensional container (tinplate containers, composite drums, rigid boxes, etc.). Distortion printing also falls into this category. 

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