Plastic Industrial Containers Although the plastic industrial container is a relative newcomer to the packaging field, the plastic carboy and the plastic drum are becoming increasingly important. They combine chemical resistance, flexibility, toughness, and lower tare weight than comparable glass or steel vessels. Most plastic containers have been made of polyethylene, but work on other materials is under way.
CARL E. PRUETT Engineering Service Division, Engineering Department, E . I . du Pont d e Nemours & Co., Wilmington, Del.
T
HE plastic industrial container is a relative newcomer to the packaging field. Metal and fiber drums, wood barrels, boxes, bags, and glass carboys have been familiar for many years. Now two new candidates have entered the field and are becoming increasingly important: the plastic carboy and the plastic drum. These containers, unknown 5 years ago, are now being used t o ship many industrial chemicals safely and economically, including some of the more dangerous ones. Two basic types of shipping containers rely on a plastic to contain the commodity: ( I ) plastic carboys of 5- t o 13-gallon capacity encased in strong outer containers of wood or plywood, and (2) plastic drums of 5- to 55-gallon capacity inserted into openhead steel drums. The first plastic container of any industrial importance awaited the introduction of polyethylene to the commercial scene, shortly after the close of World War 11. The forerunner of today’s plastic industrial containers was the polyethylene bottle, first introduced to the packaging world in 1946. Blown polyethylene bottles as large as 1 pint were available by 1949. I n that same year a polyethylene carboy was mentioned in the Journal of Commerce. Information on the successful development of a 5-gallon blown polyethylene bottle reached the Manufacturing Chemists’ Association late in 1950. A Plastic Container Subcommittee was established immediately by the Manufacturing Chemists’ Association Miscellaneous Packages Committee t o assure that this important development would have the benefit of the cooperative assistance of the chemical industry. The first meeting of this subcomittee was held in December 1950. Blown polyethylene bottles up to 1-gallon capacity were commercially available by 1951, and the first 13-gallon blown polyethylene carboys were made in that year. The development of plastic shipping containers was not as simple as this resume of history might indicate. A review of some of the problems encountered in the development of the first plastic container to receive Interstate Commerce Commission approval will illustrate this. The first problem, that of increasing the size of the polyethylene bottle t o 13 gallons, required years of research and development work by the bottle manufacturer. The next problem was to design a shipping contajner which would offer the chemical resistance and many other advantages of the polyethylene carboy and the necessary strength for transportation. This had to be done a t a price the customer could afford to Pay. POLYETHYLENE CARBOYS
The polyethylene carboy manufacturer, working with a plywood drum manufacturer, developed a shipping container which they believed would meet these requirements. This was a 13gallon polyethylene carboy encased in a strong specially designed plywood drum.
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To establish testing requirements for the proposed shipping container, the carboy and plywood drum manufacturers enlisted the aid of the Bureau of Explosives, which is utilized by the Interstate Commerce Commission in the execution of its regulations, including container testing. The bureau suggested a series of drop tests of the bare polyethylene carboy and of the carboy enclosed in the plywood drum. Recommended testing temperatures were 70’ and -10’ F. Bare polyethylene carboys were filled with water a t room temperature and dropped 6 feet onto solid concrete, so as to land in turn diagonally on the top and bottom shoulders, and flat on the top, bottom, and side. These tests were repeated on the polyethylene carboy encased in t h e plywood drum. The entire series of drop tests was repeated with. the carboys filled with calcium chloride solution a t -10’ F. These tests were conducted under the supervision of the bureau.
Figure 1.
Polyethylene carboys
The bare carboy and the complete shipping container performed satisfactorily in these severe tests. As *d. result, the^ bureau suggested that a proposed ICC shipping container specification be prepared, and recommended the assistance of the Manufacturing Chemists’ Association be utilized in the development of the specification. -4proposed ICC Specification, prepared cooperatively by the container manufacturers and t h e MCA Miscellaneous Packages Committee, was presented to the Bureau of Explosives. The Manufacturing Chemists’ Association also presented the results of storage, handling, and shipping tests conducted by several of its member companies. I n September 1952, the Interstate Commerce Commission u p
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Handling of Chemicals proved the proposed specification and it was added to the ICC -regulations as ICC-IF. The 6l/2- and 13-gallon polyethylene carboys, bare and encased in plywood drums, are shown in Figure 1, and some of the more important specfiications of this shipping container are shown in Table I.
Table I.
Specifications on Polyethylene Carboy in Plywood Drum
Capacity, gal. ‘Outage, minimum, % Weight of carboy only (approx.), Ib. Weight of complete container (approx.), Ib. ,Outside diameter of shipping container, inches -0ver-all height of shipping container, inches Wall thickness of bottle, inch Minimum, average filling opening, inches I C C specification
61/2
5 4.8 17.5 12.5 27 0.0625 0.125 2.375 ICC-IF
13 5 9 26.5 l5,4 31.5 0.0625 0.125 2,375 ICC-IF
with bare polyethylene drums, and with polyethylene drums encased in ICC-6J steel drums. All drums passed the drop tests without leakage. These polyethylene drums are capable of standing hydrostatic pressure tests in excess of 25 pounds per square inch, although hydrostatic tests are not, a t present, required by ICC regulations for plastic containers. Based on these tests and the recommendations of the Manufacturing Chemists’ Association, the Bureau of Explosives recommended to the Interstate Commerce Commission that special test permits be issued upon the request of interested shippers to authorize the temporary use of the containers with certain regulatory products. The commission accepted the bureau’s recommendations and a number of these special permits have been issued. Many thousands of these polyethylene drums encased in ICC-6J open-head steel drums are now being used for shipment of certain regulatory products under the authorjty of special ICC permits.
testimonial to the painstaking efforts of all involved in the ,development of this polyethylene shipping container is that many thousands have been placed in service over the past 2 years, and no serious complaints or damage in transportation have been reported. Commodities shipped include 60% hydrofluoric acid, hydrochloric acid, hydrofluosilicic acid, all authorized by the Interstate Commerce Commission, and many less dangerous, nonregulatory products. Several other polyethylene carboys, which serve essentially the same purpose as the ICC-1F polyethylene carboys, have been “developedand approved under specification ICC-1G.
Figure 3.
POLYETHYLENE DRUM
I n addition to the polyethylene carboy, a second and entirely .different type of plastic shipping container has been developedthe molded seamless polyethylene drum. This drum, which has 2- and 3/4-in~hstandard openings in the top head, is encased in a full open-head steel drum with the polyethylene drum opening flanges extending through holes in the cover of the steel drum. ‘This container was brought to the attention of the Bureau of Explosives and the Manufacturing Chemist’s Association in December 1952. The first molded polyethylene drum had a capacity of about 14 gallons. Subsequently, molded drums of 5-, 30-, and 55-gallon nominal capacity were developed.
Figure 2. Molded polyethylene containers Figure 2 shows several of the different sizes and shapes of molded polyethylene Containers that have been produced. Figure 3 shows a 30-gallon molded polyethylene drum, bare, encased in a plywood drum, and partially inserted in an ICC-6J steel drum. These molded polyethylene drums were tested cooperatively by the Bureau of Explosives, the drum manufacturer, and the Manufacturing Chemists’ Association. Poly*ethylenedrums, in all sizes, were filled to 98% of capacity with water, and dropped 6 feet onto d i d c?rc*.e+e. Te+ upre made .June 1955
Thirty-gallon polyethylene drum
Data are being collected on the performance of the containers under actual shipping conditions. Some difficulties have been experienced with the polyethylene flanges, and with collapse of the 55-gallon polyethylene drum when contents are discharged without removing the 3/a-inch vent plug. Changes in design and manufacturing practices have been made in an attempt to correct these difficulties. Shipping tests of the newly designed containers are currently being made. Some of the pertinent specifications of the molded polyethylene drums and their steel drum overpacks are shown in Table 11. The polyethylene carboys and the polyethylene drums have combined the chemical resistance, flexibility, toughness, and many other desirable properties of polyethylene with the ruggedness and strength of overpack containers such as wood boxes and plywood and steel drums. I n many instances, these containers provide a lighter tare weight than the normally used returnable containers such as boxed glass carboys or returnable steel drums. Table I11 shows a comparison of the plastic shipping containers and some of the other returnable containers used for regulatory products.
Table 11.
Specifications on Molded Seamless Polyethylene Drum and Steel Drum Overpack
Capacity of steel drum overpack (nominal),,gal. Capacity of polyethylene drum (approx.) gal. Weight ‘of polyethylene drum (approx.), Ib. Weight of complete container (approx.) Ib. Outside biameter of container, inches Over-all height of container, inches Opening? (Standard I.P.S.), inches Wall thickness (approx.), inches I C C specificationQ a
5
16
30
55
4.8
14
28
53
1.8
4
9,s
11,26 13.15 0.063
6.5
22 40 15.75 19.25 22.26 29 2 and 3/4 0.063 0.094 IVot authorized
Q 64 23.5 34.5 0.126
Special I C C permits are necessary for shipment of regulatory products.
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Table 111. Comparison of Polyethylene Shipping Containers with Several Frequently Used Returnable Shipping Containers Container Glass carboy in wood box (ICC-1A) Polyethylene carboy in plywood drum (ICC-1F) Polyethylene drum in ICC-GJ steel drum
Stainless steel drum (ICC-5C)
Actual Capacity, Gal. 13
Price $12
Tare Weight, Lb. 68
13.7 14 3 28 52.7
16 14 20 24
26 22 40
15.3 56
24 75
24 105
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The 13-gallon polyethylene carboy and the 14-gallon polyethylene drum are slightly higher in price than the 13-gallon glass carboy, but are substantially lower in tare weight. I n many instances the freight savings alone, due to the lower tare weight of the polyethylene container, are sufficient to justify the higher cost. The polyethylene containers, of equivalent capacity, are appreciably less expensive in first cost than stainless steel drums, and thereby permit a substantially lower investment in returnable containers. Polyethylene shipping containers should be included in container evaluations because of their possible economic advantage. In addition, there are commodities for which no other satisfactory container is available. For aqueous hydrofluoric acid up to 60% concentration glais carboys are completely unsatisfactory, as are stainless steel drums. Polyethylene shipping containers are not without limitation. Although polyethylene has excellent chemical resistance, it cannot be used for all commodities. The effect of the specific commodity on the polyethylene actually used in the specific con-
tainer under consideration should be determined carefully. The shipper alone is responsible for seeing that the container material is resistant to the commodity. What may be expected in the future? Development work is well along on fiber drum overpacks for the polyethylene carboy and the polyethylene drum, and fiber drum overpacks probably will be eventually included in the ICC regulations. One manufacturer has approached the Bureau of Explosives with a container consisting of a polyethylene carboy encased in an open framework of steel rod. The M C S Miscellaneous Packages Committee is currently engaged in test work to demonstrate the adequacy of this container for the shipment of dangerous commodities. 9 preliminary study recently conducted by the MCA Miscellaneous Packages Committee, to determine the relative puncture resistance of polyethylene compared to that of several other container materials, has yielded some interesting information. A continuation of this work along Tvith development work on the part of plastic container manufacturers may lead to a polyethylene container which can be shipped safely without an overpack. OTHER PLASTICS
Most of the plastic industrial container work to date has been done with polyethylene. Work now under way indicates that modifications of polyethylene with other materials may improve its performance with certain commodities. What of the many other plastics? Will they, too, find application in industrial containers? The future, of course, holds the answer to these questions, but plastic containers will play an increasingly important part in the future, in the safe and economical transportation of the many products of the chemical industry. RECEIVED for review October 15, 1954.
. ~ C C E P T E D March
25, 1955.
Aerosols in the Smaller Bulk Container Field Although aerosol products appeared on the market only 9 years ago, 1953 production was valued at $160,000,000, and more than 60 types of products are reaching the consumer. Aerosols are pressurized, self-spraying units that deliver an active ingredient in a spray, a foam, or a dry powder. Behind them all is the convenience of the push-button container, with its liquefied gas that can expand more than 240 times when released from pressure. Research is developing more corrosion-resistant containers, safer containers, and better valves with a wider range of usefulness.
H. W. HAMILTON Chemical Specialties Manufacturers Association. h e . , Xew York 17, S. Y .
LOOK at aerosol products from the viewpoint of the large scale package producer might be likened to hunting out one particular tree in a huge forest for, volumewise, the aerosol industry’s appetite for containers is small compared with the demand for more common types of containers. I t is an appetite that is increasing, however, and may, not too many years hence, occupy a sizable portion of the packaging platter. ilerosol products are pressurized, self-spraying products that a t the press of a valve button deliver an active ingredient in a fine spray (insecticides and room deodorants), a heavier spray (paints and enamels), a foam (shave creams), and newest among the applications, a dry powder.
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Although aerosol products appeared on the consumer market only 9 years ago, with insecticides as the initial application, they have grown steadily in volume from the 1947 production of 5,000,000 units to 140,000,000 units in 1953, with a retail value in the neighborhood of %160,000,000. I n 1954 the industry, spurred on by introduction of ultra-lowpressure glass and plastic containers probably turned out at least 200,000,000 units of products, at a retail value of about $220,000,000. More than 60 different types of products are now reaching the consumer in self-spraying aerosol containers. I n addition to the product types already mentioned, they include such household
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