US2530413A

US2530413A - Container

Info

Publication number: US2530413A
Application number: US625246A
Authority: US
Inventors: Albin H Warth
Original assignee: Crown Cork and Seal Co Inc
Current assignee: Crown Cork and Seal Co Inc
Priority date: 1945-10-29
Filing date: 1945-10-29
Publication date: 1950-11-21
Anticipated expiration: 1967-11-21

Description

Nov. 21, 1950 A. H. WARTH 2,530,413

CONTAINER Filed Oct. 29, 1945 Patented Nov. 21, 1950 conranvcn Albin n. Warth, Baltimore, Md., assignor to Crown Cork & Seal Company, Inc., Md., a corporation of New York Baltimore,

Application October 29, 1945, Serial No. 625,246

3 Claims. (Cl. 22064) This invention relates to containers particularly those for packaging foods and beverages, in which a metallic surface comes into contact with the container contents. In addition, the invention isconcerrfed with new alloys, metal coated with these new alloys and containers comprising such alloys.

Considerable difliculty has been encountered in the production of completely satisfactory containers and packages for food and beverages, particularly those of a high acidic content such as citrus fruit juices and the like. As is fully described in my co-pending application, Serial No, 439,292,-filed April 16, 1942, and now abandoned, ordinary tin plate is not an entirely satisfactory material from which to fabricate containers for fruit juices because of the loss of aroma, flavor and discoloration of the contents upon ageing in the container. On the other hand, the use of containers in which a metallic surface is exposed to the container contents is advantageous in the packaging of acidic foods and beverages if the metal surface exposed evolves a minute amount of nascent hydrogen during storage of the packaged product. This advantage resides in the ability of the nascent hydrogen to maintain the packaged material free from oxidation and other resulting changes in flavor and discoloration which accompany the oxidation processes. In this respect, containers having a metal surface exposed to the packaged product are superior to containers in which only non-metallic surfaces are exposed to the acidic packaged material, e. g., containers of glass or metal containers lined with enamel or organic resinous coatings.

Ordinarily, tin plate is the most common material used in the preparation of food or beverage containers made wholly or partially of metal. However, this material is not entirely satisfactory for use in the packaging of acidic foods and beverages because of excessive chemical attack upon the tin plate by the container contents. Various modifications of tin plate have been attempted in order to overcome this disability, e. g., the use of an alloy of tin with minor amounts of silver, as in my above mentioned patent application, for the production of coated sheet metal to be employed in the production of the containers. However, even these improvements over the common tin plate have not resulted in the elimination of all of the deficiencies associated with containers made from such coated metals. Thus, the silver modified tin plate is subject to tarnishing and its corrosion resistance is not as high as is desirable.

. tainers as described above.

A principal object of this invention is to overcome all of the deficiencies of the subject con- A further object is the provision of containers having at least a portion of the surface exposed to the container contents made from metal, said metal surface being highly resistant to corrosion and oxidation.

A further object is the provision of plated sheet metal having a plating which is tougher than tin and containers fabricated from such plated metal. Another object is the provision of plated metal from which food and beverage containers may be produced which exhibit extremely good soldering characteristics. Further objects and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter.

These objects are accomplished according to the present invention by the preparation of an alloy comprising tin, silver and indium, the plating of a base metal sheet with this alloy and the fabrication of containers for foods and beverages from such alloys or coated metal sheets in which any of the metal surfaces of the container exposed to the packaged material is made of the alloy.

The success of this invention resides primarily in the discovery that an alloy composed of a major proportion of tin and a minor proportion of silver and indium provides a sufllcient amount of nascent hydrogen upon contact with acidic foods or beveragesto keep the true flavor of container contents during storage whil exhibiting an extremely good degree of chemical and corrosion resistance and attractive appearance without tarnishing or undergoing oxidation. The manner in which this discovery is utilized may be stated as follows:

Sheet metal, such as black iron or steel of a gauge or thickness adapted to permit fabrication of containers from the metal is coated with an alloy comprising tin, silver and indium, such as an alloy of 93 to parts of tin, 0.1 to 3.5.palts of silver and 0.03 to 3.5 parts of indium. The coating of the metal sheet may be accomplished by a hot dipping procedure, i. e., by dipping the sheet in the molten metal alloy; by an electrolytic process, 1. e., plating the sheet metal in an electrolytic bath of an acid or alkaline nature containing silver, tin and indium in the proper proportions to yield the desired coating; or by a vaporlytic process, i. e., by vaporizing thealloy in a vacuum chamber and condensing the vapor upon the sheet metal plate. Moreover, acontainer may be fabricated from the uncoated base 3 metal plate and then coated with the alloy by any of the methods indicated above.

The alloy need not be used for making the entire surface of the container, but is also satisfactory for use in the preparation of container closures having an overall or center-spot facing coated or made from the alloy. Thus, a tin metal foil may be coated with the alloy for production of container closures facings or thin foil may be prepared from the alloy. Such foil may be made in substantially the same manner as is used to prepare tin metal foil, e. g., rolling. The tin-silver-indium foil can be also mounted on paper material by means of a thermoplastic adhesive, preferably by coating thepaper and then by means of heat and pressure wedded to the metal foil. The advantage is that a somewhat thinner foil can be successfully used, namely, .001" foil or a trifle less, which can be mounted on a paper having .002" thickness or a trifle less. When using silver-tin-indium foil without paper mounting, a thickness of at least 0.0015" is used, due to rupture of thinner foils in the mechanical assembly of the spot or overall facing on the disc or solid liner of the crown. Ordinary tin foil is not generally used with a thickness of less than .002" for Spot Crowns, but the silver-tinindium foil is stronger and somewhat easier to handle and a lesser thickness may be satisfactory, but usually the .tin-silver-indium alloy foil is of a thickness in the neighborhood of about .002".

For the purpose of illustrating the invention I have shown in the accompanying drawing a container and a cap coated with the silver-tinindium alloy. It is to be understood that various types of containers and caps as well as other articles employed for packaging foods and beverages may be similarly lined or provided with exterior coating as described herein.

Referring to the drawings:

Figure 1 is an elevation partly in section of a can such as a sanitary type can having a lining of the tin-silver-indium alloy.

Figure 2 is a sectional view of a can-end for use with the can of Figure 1, similarly lined,

Figure 3 is a sectional view of a crown cap having its exterior surface coated with my improved alloy, and

Figure 4 is a sectional view of a crown cap having a cushion liner coated with a film of the tinsilver-indium alloy on its exposed surface which may be in the form of an overall or center-spot facing.

The can ill shown in Figure 1 is provided with a seam II, which may be sealed with either ordinary solder, with tin-silver-indium solder or similar materials. Alloys of tin with 3% to percent silver may be used for solders that require greater corrosion resistance than lead-tin solders, or where it is desirable to eliminate the toxic lead. The alloy lining is indicated at 13 and is coextensive with the interior wall of the container. The alloy may also be coated upon the exterior of the can to be coextensive therewith, and

I have found that it is highly receptive of the usual can decorations and likewise imparts a bright finish.

The end shown in Figure 2 is the customary can end for sealing a standard sanitary can, as

shown in Figure 1, and has its inner or exposed surface coated with the alloy lining I 3. The exterior surface of the end may also be similarly The cap it shown in Figure 3 has a cushion liner l1 and has its exterior surface provided with an alloy coatin of tin-silver-indium alloy in accordance with this invention. This coating, as just stated, will impart a bright finish and will readily receive the lithograph or other printing decoration. The standard sanitary can shown in Figure 1 is made of metal plate such as black iron or steel, previously coated with the improved tin-silver-indium alloy and then folded or bent in the usual manner into a can body by the customary body making machinery and the seam ll sealed in the regular way. The cap is likewise made from coated plate, but instead of being bent to form, is stamped or drawn from the coated sheet.

Referring to Figure 4, the crown cap is provided with a cushion liner i 5 of paper board, cardboard, or other solid material and has secured to it exposed face a film It of the tinsilver-indium alloy as described herein, e. g., tinsilver-indium alloy foil and constituting an overall or center-spot facing.

A more complete comprehension of the present invention may be had from the following illustrative example, in which all parts are by weight:

Example .This example illustrates the preparation of container of the sanitary can type from sheet metal prepared by hot dipping process.

A hot dipping bath is prepared by melting together 20 parts of silver, '7 parts of indium and 970 parts of tin containing 3 parts of impurities. The melting point of this resulting alloy is about 230 C. and bright finish black plate is readily coated with the alloy using an ordinary dipping process, since the alloy has excellent flowing qualities and readily wets the sheet metal base.

The coated sheet metal is fabricated into a container of the sanitary can type, such as that illustrated in Figure l, by the general can making procedure. It is found that this metal is particularly useful for this purpose in view of the ease with which the can seams may be soldered.

Orange juice. is packaged in the resulting container. After storage for a considerable time, the

orange juice is found to possess substantially the same color, aroma and flavor which it had before packaging. Moreover, all of the surfaces of the container exposed to the atmosphere during storage retain a bright, untarnished appearance and the inner can surfaces show substantially no signs of corrosion.

In another case, sheet metal was coated with ordinary tin and this tin plate was used to prepare containersand package orange juice. The orange juice stored in this latter container for the same period of time as the former, was found upon inspection to possess a distinctly changed aroma and flavor as compared to the orange juice originally packaged.

In still another case a container was made from sheet metal coated with an alloy of 97 parts of tin and 3 parts of silver. The chemical resistance of this last container to the action of the packular type of container into which the alloy is to be fabricated and upon the type of metal to be packaged in the container. The most desirable.

alloys appear to be those in which the propor tion of tin to silver is between 1000 to 1 and 27- to 1 and in which the proportion of silver to 1 indium in the alloy is between 1 to 1 and 7 to 1.

Particularly useful alloys are those comprising 93 to 100 parts of tin, 0.1 to 3.5 parts of silver and 0.03 to 3.5 parts of indium. An especially useful alloy is composed of 97 parts of tin, 2 parts of silver and 0.7 part of indium.

This invention provides new and useful alloys which may be employed for applications where high degrees of chemical resistance coupled with high degrees of toughness are required. Although these alloys are, generally useiul for these purposes,-they are particularly applicable to the production of containers and container closures for packaging foods and beverages, particularly those of an acidic nature.

I claim:

1. A sheet metal container having a coating on its wall 01' an alloy omposed of 93 to 100 parts of tin, 0.1 to 3.5 parts of silver and 0.03 to 3.5 parts of indium, except for incidental impurities.

2. A container closure having on .its interior a coating composed of 93 to 100 parts of tin, 0.1 to 3.5 parts of silver and 0.03 to 3.5 parts of indium, except for incidental impurities.

3. An alloy composed of 93 to 100 parts of tin,

0.1;;to 3.5 parts of silver and 0.03 to 3.5 parts of indium, except for incidental impurities.

, ALBIN H. WARTH.

REFERENCES CITED Th iellowing references are of record in the flle ifthls;patent:

': STATES PATENTS Number Name Date 135,028 Zimmer Jan. 21, 1873 250,326 DeVllliers Nov. 29, 1881 1,437,641 Ferriere et al. Dec. 5, 1922 1,626,038 Ireland Apr. 26, 1927 1,632,309 Nitardy June 14, 1927 1,958,765 Perkins May 15, 1934 2,151,032 Scheller Mar. 21, 1939 2,157,933 Hensel et a1 May 19, 1939 2,241,789 Queneau et a1 May 13, 1941 2,364,713 Hensel Dec. 12, 1944 2,373,352 Smart Apr. 10, 1945 2,393,905 Hensel Jan. 29, 1946 FOREIGN PATENTS Number Country Date 565,072 Great Britain Oct. 25, 1944 Product Engineering, Oct. 1943, pages 630-632.