US3660188A

US3660188A - A method of recycling and reconditioning a metal shipping container

Info

Publication number: US3660188A
Application number: US869245A
Authority: US
Inventors: Oscar J Van Leer
Original assignee: Inland Steel Co
Current assignee: Inland Steel Co
Priority date: 1969-10-24
Filing date: 1969-10-24
Publication date: 1972-05-02
Anticipated expiration: 1989-05-02

Abstract

A method of recycling a drum shaped metal shipping container which has at least two parts in overlapping relationship, the overlapping portions of said parts being secured together in liquid tight relation by an adhesive substance which when subjected to heat or an appropriate dissolving agent disintegrates so that said parts may be disassembled to make the container interior fully accessible for reconditioning. The adhesive substance is disintegrable and completely removable from the container parts without deforming the container parts or affecting the metallurgical properties of the parts.

Description

United States Patent 51 3,660,188 Van Leer 451 M 2, 1972 [54] METHOD OF RECYCLING AND 2,936,261 5/1960 Cole ..156/283 x RECONDITIONING A METAL 5 323 S l 1 SHIPPING CONTAINER 2,943,386 7/1960 [72] lnventor: Oscar J. Van Leer, North Holland, 3,454,179 7/1969 Netherlands FOREIGN PATENTS OR APPLICATIONS [73] Assignee: Inland Steel Company, Chicago, Ill.

203,562 8/1955 Australia 156/322 1 Filed: l- 1969 884,225 l2/l961 Great Britain... Appl' 869345 Primary Examiner-Benjamin A. Borchelt Related s Application Data Assistant E.\'aminerDaniel Bent Att0rney-Wolfe, Hubbard, Voit, Leydig & Osann, Ltd. [63] Continuation-impart of Ser. No. 648,647, June 26,

1967, abandoned. [57] ABSTRACT 52 U.S. c1 ..1s6 94,113 '12o A method of recyling adrum ap d metal shi in con- 5 1 1 1111.01 .3321) 35/00 mine which has least Parts in relaimlshipv 58 Field 6: Search ..'.220/5, 5 A, 67, 68, s1, so; 0"erlaPPing said lEms being sewed together 1 125/1201, 120 BB 120 K, 120 M, 120 N 120 Y; in liquid tight relation by an adhesive substance which when l56/94 98 283 322 344 subjected to heat or an appropriate dissolving agent disintegrates so that said parts may be disassembled to make the [56] Reterences Cited container interior fully accessible for reconditioning. The adhesive substance is disintegrable and completely removable UNITED STATES PATENTS from the container parts without deforming the container parts or affecting the metallurgical properties, of the parts. 1,461,729 7/1923 Foster et a1. ..1 13/120 L UX 2,424,188 7/1947 Pearson ..220/81 X 6 Claims, 9 Drawing Figures A METHOD OF RECYCLING AND RECONDITIONING A METAL SHIPPING CONTAINER DESCRIPTION OF THE INVENTION The present invention relates to recycling metal shipping containers and reconditioning such containers. This application is a continuation in part of the copending US. Pat. application of Oscar J. van Leer, Ser. No. 648,647, filed June 26, 1967, now abandoned.

Metal shipping containers are widely used for packaging, storage, and transport of materials such as crude oil products, food products, liquid chemicals, paints and other liquid, semiliquid, pulverous or granular materials. In use, these containers may become damaged, dented or otherwise deformed. The contents also are frequently of the character which, after emptying the container, leave a residue in the container which cannot satisfactorily be removed when an attempt is made to use the bung opening which provides an orifice of but limited size for access to and cleaning of the eontainers interior. A larger opening therefore must be made which permits the insertion of suitable tools or devices for the removal of dents and otherwise reshaping the walls of the container if necessary. To this end, it is known to cut the empty container into two halves, clean and reshape the halves and again weld the two parts together. This process, in addition to being a complicated operation, may considerably reduce the capacity of the container if repeated several times.

Accordingly, it is a general aim of the present invention to provide a shipping container the interior of which can easily and fully be made accessible for reconditioning and which after having been reconditioned can be closed again to produce a complete containerwhich has the same capacity and is indistinguishable from the original container.

It is an associated object to provide a shipping container as characterized above which may be simply and economically disassembled for cleaning and reconditioning without damaging or deforming any parts of the container.

More particularly stated the present invention provides a container as set forth above which has essential parts intercom nected by an adhesive substance that is disintegrable and completely removable when subject to predetermined conditions so that the container parts may be disassembled for cleaning and reconditioning, and then reunited by applying a fresh adhesive substance to again produce a complete container having the same capacity as originally.

Still another aspect of the invention is an improved method for producing and reproducing a metal shipping container which is simple and economical and facilitates reconditioning of the container without deforming any container parts.

Other objects and advantages of the invention will become apparent as the following description proceeds, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side elevation in partial section of a container made according to the present invention;

FIG. 2 is an enlarged vertical section of the upper part of the container shown in FIG. 1;

FIG. 3 is an enlarged vertical section of the lower part of the container shown in FIG. 1;

FIG. 4 is an enlarged fragmentary section showing the connection of the end wall to the side wall of the parts shown in FIGS. 2 and 3;

FIG. 5 is an enlarged fragmentary section of the joint between the upper and lower parts of the container shown in FIG. 1;

FIGS. 6-8 show alternative forms of joint between the upper and lower parts of the container; and

FIG. 9 is a fragmentary section of a modified form of end wall construction.

While the invention is susceptible of various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but, on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as expressed in the appended claims.

Referring now to the drawings, there is shown in FIG. 1 an exemplary drum shaped shipping container 10 including a cylindrical side wall portion 11 enclosed by upper and

lower end walls

12, 13 respectively. The walls of the container preferably are made from steel sheet metal, although it will be apparent that other materials could be used as well. The upper end wall 12 is provided with a filling and emptying opening 14 and an air inlet and escape opening 15. To make the container liquid tight, the openings 14, 15 can be provided with appropriate removable closures.

In order to permanently and reliably seal the

end walls

12, 13 to the side wall 11 and at the same time enhance the rigidity of the structure, the end walls are cup shaped and a reinforcing ring 20 isprovided at both ends of the container which surrounds the joint between the end and side walls. The cup shaped end walls each have a substantially flat bottom 21 and a skirt 22 interconnected by a curved portion 23. The skirt 22 fits adjacent the side wall 11 and the parts may be secured together in any convenient manner, such as by welding. The reinforcing ring 20 has a radial leg 25 mounted on the flat portion 21 of the end wall and axial leg26 engaging the inner side of the side wall 11 at its extremity and is folded together with the side wall outwardly into a bead 27.

In accordance with the invention, the container can be divided into at least two parts so that the interior of the container is easily and fully accessible for reconditioning. After reconditioning the parts are adapted to be reunited to produce a complete container having the same capacity and being indistinguishable from the original container. In the embodiment illustrated in FIGS. l-S, the container includes upper and

lower parts

30 and 31, respectively, which mate in overlapping relationship in the approximate circumferential plane of the cylindrical side wall 11. Each of the

parts

30, 31 comprises one of the end walls and a portion of the container side wall 11. To facilitate the handling of the

parts

30, 31 during manufacture and assembly, the height of each part may be made approximately half the height of the complete container.

In order that the upper and lower parts may be formed in overlapping relationship, the upper part is fonned with a flaring extremity 32 while the lower part has a corresponding tapered extremity 33 of the same inclination, which is shown as approximately 10:1. In order to cause a tapered extremity 33 to be immediately adjacent the flaring extremity 32 while the cylindrical side wall portion of each part has the same diameter, the tapered extremity 33 of the lower container part joins a flaring portion 34 which causes the'tapered extremity 33 to commence at a larger diameter. Thus, the lower part 31 has an extremity in the form of two truncated cones placed with their bases against each other. To facilitate manufacturing, the flaring portion 34 may have the same inclination and width as the flaring extremity 32 and be spaced an equal distance 'from its respective end wall so that the same die may be used in manufacturing both

parts

30 and 31.

In carrying out the'method of the invention and in order to secure the upper and lower container parts together, an adhesive substance is provided between the overlapping portions of the side walls, said adhesive being of a type which disintegrates when subjected to predetermined conditions so that the parts of the container may be readily disassembled for reconditioning. As shown in FIG. 5, an adhesive substance 35 is provided between the tapered extremity 33 of the lower part and the overlapping flaring extremity 32 of the upper part. The adhesive substance should be an appropriate material which will securely hold together the container parts in liquid tight relation and will withstand shock to and deformation of the walls during use of the container. To permit disassembly and reconditioning of the container, however, the adhesive when subjected to predetermined conditions should be disintegrable and completely removable from the container parts without deforming the parts of afiecting the physical properties of the parts. Thus, the adhesive may be a substance which dissolves when a suitable solvent is applied, or which disintegrates when subjected to heat, either by melting or becoming brittle so that it falls into pieces when an external force is applied which is sufiicient to separate the parts of the container but insufficient to deform the parts. When a heat destructible adhesive substance is used to secure metal container parts, the adhesive preferably should be disintegrable at temperatures which do not exceed 600 C. so that metallurgi: cal properties of the container are not affected. To increase the strength of the joint in a metal container, it may be desirable to apply an intermediate compound to the mating surfaces in addition to the adhesive to compensate for any oxidation preventing substances present at the metal interface.

According to the preferred embodiment of the invention,

the adhesive substance is a thermoplastic material such as a layer of expandable polyethylene. To promote oxidation and overcome the effect of oxidation preventing substances between the polyethylene and mating metal surfaces of the container, the surfaces may be coated with an intermediate layer of metal organic compound paint drier such as epoxy phenolic lacquer. The coated areas are then heated and a polyethylene powder is applied to the hot areas. The excess of powder is shaken off, and the powdered sides are pressed against each other and simultaneously heated until the adhesive bond is completed between the parts. Such a polyethylene adhesive may be sufficiently cured at temperatures which do not exceed 200 C.

The use of expandable polyethylene as the adhesive provides the advantage of filling any irregularities in the surfaces to be joined so as to achieve a liquid tight and uniform bond. The resulting bond also has a high stretchability and sheer resistance so that the joint will withstand significant impact shocks and deformation during handling and use of the container without affect the liquid tight seal. However, by merely heating the polyethylene adhesive on the overlapping parts to a temperature in the range of 500 to 600 C., the adhesive will become brittleand disintegrate to permit easy disassembly of the container parts. The adhesive may then be completely removed from the container walls without adversely affecting the walls.

Since the temperature required in curing the polyethylene adhesive to secure the container parts is relatively low, an internal protective coating may be applied to the parts prior to their assembly. Most protective coatings, such as organic lacquers, are not affected by the polyethylene curing temperature which preferably is below 200 C. In addition, since relatively low temperatures are involved in both curing and disintegrating of the adhesive, simple and economical heating means may be employed. Moreover, heating may be limited substantially to theadhesive and the overlapping portions of the container parts. Such local heating has the advantage of permitting the remaining portions of the container to remain sufficiently cool to be handled manually. The lower heat input also attributes to cheaper manufacturing and reconditioning operations and facilities.

It is understood that many low metal alloys, araldites, and metal glues alternatively could be employed as effective adhesives. In each case, however, the adhesive should be of a type which permits application and removal at temperatures of less than 600 C. Thus, welding and brazing techniques would not be satisfactory. Such processes necessitate significantly higher temperatures which would destroy the necessary metallurgical properties of the container in the joint area, as well as any protective coating applied to the interior of the container parts prior to assembly. The high welding and brazing temperatures also would tend to fuse or alloy the welded metal to the container walls, making it difficult, if not impossible, to adequately remove the fused metal during reconditioning without damaging the container.

It also should be appreciated that due to the tapered and flared overlapping

extremities

32, 33 of the container shown in FIGS. 1-5, the container parts are rigidly held together without slipping or shifting during the time the fresh adhesive is setting. Such stability ensures the creation of a good bond and also establishes an exact capacity of the container each time the parts are assembled.

In view of the above, it is apparent that the container made according to the present invention is a liquid tight and rigid unit of an exact capacity. After the container has been used on one or more occasions it may be readily divided into two parts by melting or otherwise disintegrating the adhesive substance so that the interior of the container is easily accessible for cleaning and reconditioning. Reconditioningmay include not only painting and reshaping of the container, but also removing, replacing, or adding a desired lining or coating to the container interior or exterior. After reconditioning, a fresh adhesive substance can be applied and the parts united again to produce a complete container which may have the same capacity and be indistinguishable from the original container. The separation of the parts by disintegrating the adhesive substance is a simple operation which does not destroy or deform any parts of the container and does not alter them in any irreversible way.

FIGS. 6-8 illustrate alternative ways in which the container may be made up of overlapping parts secured by an adhesive substance according to the present invention. The container of FIG. 6 is similar to the above described embodiment. The cylindrical container side wall includes one part 50 formed with an outer tapered extremity 52 which is joined to the cylindrical portion of the side wall by a flared portion 53. The other part 51 of the side wall is formed with-a flared extremity 54 overlapping the tapered extremity 52 and secured thereto by an adhesive substance 55. In this embodiment, the tapered extremity 52 is folded back at its extreme edge to form a thick portion 56. The folded back edge 56 not only reinforces the edge but also seals the adhesive layer 55 from the contents of the container,especially when the tapered extremity 52 extends beyond the placed sectum 54 into a cylindrical portion 57 of the container.

In the embodiments shown in FIGS. 7 and 8, the container side wall is formed with two identical halves in juxtaposed abutting relation and an annular part is provided adjacent the abutting extremities. In FIG. .7 the container side wall has two halves 60, 61 each formed with flaring

extremities

62, 63 interconnected by means of an inner double coned ring 64 adhered to both

extremities

62, 63 by an adhesive substance 65. FIG. 8 shows a similar construction in which, however, the two

identical halves

70, 71 of the container side wall have tapered

extremities

72, 73 joined with each other by means of an outer ring 74 and an adhesive substance 75. The use of identical container parts in the embodiments of FIGS. 7 and 8 facilitates both manufacturing and reconditioning of the parts.

It is apparent that the container parts secured. by the adhesive substance may take still other forms. For example, the overlapping wall parts may be cylindrical with one part having an outer diameter which is smaller than the inner diameter of the other part such that an adhesive can be present between the overlapping portion. Moreover, instead of providing the overlapping joint intermediate the ends of the side wall, alternatively the end'walls of the container could be secured to the side wall by means of such an adhesive substance. In each case, the container parts to which the adhesive is applied should be in overlapping relationship at approximately the circumferential plane of the side wall so that the container may be disassembled to provide full access to the interior.

In addition, it will be apparent that the end walls of the container may take other forms. However, to facilitate reconditioning and cleaning of the container after it is disassembled, the end walls preferably should have as few crevices as possible. As shown in FIG. 9, a modified form of end wall is welded to a container side wall 81 to form a crevice free end closure that is especially suited for thorough cleaning. The end wall 80 in this case is of a one piece construction having a skirt portion 82 and a recessed central portion 84. The recessed central portion 84 forms a reinforcing channel 85 and pennits an opening ring 86 to be disposed below the end surface of the container. The skirt 82 is secured in abutting relation to the side wall 81 by an appropriate weldment so that there are no crevices created by the joint between the two members. Again, as in the previous embodiment, the end wall 80 is permanently secured to the side wall 81, while the side wall may be separable to permit reconditioning of the container.

In view of the above, it can be seen that the container of the present invention is produced and reproduced by an improved novel method which is simple and economical and facilitates reconditioning of the container parts It has been shown that the container is produced by forming parts which when assembled are in partially overlapping relation, assembling the parts together, and securing the overlapping portions of the parts to one another in liquid tight and rigid relationship by means of an adhesive substance that is disintegrable when subjected to predetermined conditions to permit separation of the parts without deforming or damaging the parts.

I claim as my invention:

1. A method of reconditioning a reusable metal shipping container of the type which has at least two parts in overlapping relationship, the overlapping portions of said parts being secured together in liquid tight relation by a thermoplastic adhesive substance which remains distinct from the metal of container parts and which is disintegratable when subject to predetermined conditions comprising the steps of disintegrating said adhesive substance while maintaining said container parts in the same physical shape and with the same metallic strength and flexibility as when said parts were secured by said adhesive, separating said container parts to make accessible the interior of said container parts, removing completely the disintegrated adhesive from said parts, reconditioning and cleaning said container parts, applying a fresh coating of said adhesive substance to the portions of said container parts which overlap when said container is in an assembled condition, and reuniting said container parts to produce a complete container having the same capacity as originally.

2. The method of claim 1 in which said adhesive is disintegrated by heating said adhesive to a temperature below that which affects the metallic strength and flexibility of said adjacent container parts.

3. The method of claim 2 in which said adhesive is disintegrated by heating it to a temperature not in excess of 600 C.

4. The method of claim 2 in which heating to disintegrate said adhesive is limited substantially to the overlapping portions of said parts and said adhesive.

5. The method of claim 1 including applying a protective coating substance to the interior of said container parts after cleaning of said parts and prior to applying a fresh adhesive coating, and applying said adhesive and reuniting said parts without destroying said protective coating substance.

6. The method of claim 2 in which an expandable polyethylene adhesive is applied to said overlapping container portions.

Claims

2. The method of claim 1 in which said adhesive is disintegrated by heating said adhesive to a temperature below that which affects the metallic strength and flexibility of said adjacent container parts.
3. The method of claim 2 in which said adhesive is disintegrated by heating it to a temperature not in excess of 600* C.
4. The method of claim 2 in which heating to disintegrate said adhesive is limited substantially to the overlapping portions of said parts and said adhesive.
5. The method of claim 1 including applying a protective coating substance to the interior of said container parts after cleaning of said parts and prior to applying a fresh adhesive coating, and applying said adhesive and reuniting said parts without destroying said protective coating substance.
6. The method of claim 2 in which an expandable polyethylene adhesive is applied to said overlapping container portions.