US3366233A - Packaged asphalt - Google Patents

Description

Jan. 30,. 19 6 8 c. ROEDIGER 3,366,233

PACKAGED ASPHALT Filed Sept. 26, 1966 J. C. ROE'D/GER INVENTOR A N AI ORNVEV United States Patent 3,366,233 PACKAGED ASPHALT Joseph C. Roediger, Westfield, N.J., assignor to Esso Research and Engineering Company, a corporation of Delaware Filed Sept. 26, 1966, Ser. No. 581,763

- 9 Claims. (Cl. 20684) ABSTRACT OF THE DISCLOSURE Asphalt is packaged in a mnltilayered or laminated container or encasement of sheeting or film of poly alpha olefin having a melt index below about 12 (measured at 230 C.) and being composed of polyethylene, polypropylene or the plastic or plastomeric copolymer of ethylene and propylene. Thesheeting or film ranges in thickness between about 2 and about 6 mils.

This invention relates to asphalts packaged in a novel way. More specifically, the invention relates to the ordinary standard paving asphalt compositions of commerce and specifically relates to methods of packaging the same for shipment from the refineries where such asphalts are produced to the mixing plants located in relatively close proximity to the sites where such asphalts are ultimately used.

For many years asphalts have been prepared in oil refineries from a variety of specific crudes. For the most part these asphalts are the residual fractions derived from such crudes as Mexican, Venezuelan, Columbian, California, Mid-Continent, and Talco. The asphalts as produced at the refineries in molten condition are pumped through steam traced or packeted lines at temperatures sufficiently high so that the pumps can handle the molten materials. Such asphalts are customarily and commercially shipped by tank car, tank truck, barge, and in metal drums. If the asphalt has a very high softening point, as is the case with many oxidized coating asphalts, the tanks or barges are equipped with internal heating coils and the tanks can also be insulated so that it is easy to discharge the asphalt in liquid form from its shipping containers. In many instances the oxidized coating asphalts of 165 to 180 F. softening point or higher are frequently packaged in fiber drums or other packaging material having an internal clay-resin, resin-silicone, or clay-silicone composition lining which subsequently permits peeling the drum from the asphalt, provided the pack- ;aging material has sufficient strength to permit stripping the material from the asphalt without tearing. In other instances the asphalts are shipped in thin metal drums of 24 gauge or lighter and the drums are destroyed or only used once for the purpose. All of these are effective starting materials for high softening point asphalts but are sometimes not satisfactory for lower consistency asphalts, i.e., 80 -l40 F. softening points (ASTM D-36).

Considerable effort has been made in the past to employ low cost systems for packaging paving asphalts which are generally of lower softening points. Treated (coated) paper bags have been attempted for this purpose but are not satisfactory. Such bags were coated on the inside or else thebags themselves were paper bags which were reinforced or laminated with their interiors being plastic films. Practically all regular paving grade asphalts have from 70 to 95% of oily constituents in admixture with a dispersion of 5 to 30% asphaltenes. The oily constituents have a tendency to exude from the asphalt into the container material so that if paper bags filled with asphalt are stacked one upon the other, the oily. constituents work through the paper and the bags tend to become tacky and stick together. Additionally, in attempting to empty the asphalt from the paper containers at the mixing plant at ambient temperatures, the asphalt is so soft and sticky that it is practically impossible to separate the paper from the asphalt. Particularly with the soft paving grade asphalts, the oil exudation is a problem and it is not possible in a practical manner to strip the fibrous container from the asphalt.

It is desirable, however, to be able to ship paving grade asphalt compositions in bags or wrapped in and encased 'in films or sheets of material which either slow the oil exudation into the containers or wrappers to a minimum or which eliminate such staining and exudation altogether. In this way, the filled containers will have a minimum tendency to stick together and can be easily handled. Such shipments in bags are especially desirable where paving asphalts are to be used in remote areas where it is not economically feasible to ship the asphalt compositions from the refinery by railroad tank car, tank truck, or barge.

It is, therefore, an object of the present invention to devise a material for the encasement of paving grade asphalt either in a bag or in a liquid tight wrapper which material resists or minimizes the exudation of the oily constituents of the asphalt. It is a further object of the invention to fabricate a container material for transporting paving asphalts which container does not become tacky or sticky when the containers are stacked on top of each other, which is low cost and which is non-returnable. It is a further object of the invention to provide containers for paving asphaltic compositions made of materials which are compatible with the asphalt and remain incorporated into the asphalt under conditions of ultimate use and which are easily handled and readily transportable. These and other objects of the invention will be come apparent upon a fuller understanding of the invention.

It has now been discovered that films or sheetings, ranging in thickness from 2 to 6 mils, preferably from 2.5 to 3 mils in thickness, of the polymeric mono alpha olefins having melt indices (measured at 230 C.) of 12 or below, preferably melt indices between about 7 and 10, constitute highly satisfactory materials into which such asphalts may be encased for transshipment to the ultimate users or to mixing plants adjacent to the ultimate sites of use. Such polymers are typically polyethylene, polypropylene or the copolymer of ethylene with'propylene wherein the relative amounts of ethylene and propylene are either 1 to 10% of ethylene with the remainder being propylene, or 1% to 10% of propylene with the remainder being ethylene. Larger amounts or more nearly equal amounts of ethylene and propylene produce elastomeric ethylene/propylene compositions and these are not satisfactory for the intended use because they do not have suflicient tensile strength to serve the purpose. The plastic and plastomeric ethylene/propylene copolymers are suitable for making the sheeting material which can be used in producing the novel articles of commerce herein described. Additionally, in order to minimize the conveyance of the oil constituents of asphalt through the polyolefinic sheeting materials and to insure that the objectionable features of tackiness and stickiness are eliminated, it has been found to be necessary to use at least two layers of the sheeting material. These two layers of the sheeting material may be in the form of a laminate or they may constitute two separate pieces of sheeting as, for example a double walled bag. For example, two unlaminated films of polyethylene forming a bag is excellent for impeding oil pick-up and transmission. Laminated two layer polyethylene bags are also highly useful but do transmit oily components of paving grade asphalts to a somewhat greater degree than the unlaminated multilayered polyethylene bags. In the preparation of bags that are made of laminated films, any suitable adhesive may be employed which is ultimately compatible and will dissolve in the asphaltic material contained in the bag or wrapped in the laminated sheeting. One highly suitable adhesive is the petroleum resins of commerce. These, their method of production, their properties and uses in paving compositions are fully described in U.S. Patent No. 3,070,570, patented Dec. 25, 1962, which disclosure is incorporated herein by reference. Other more conventional polyolefin adhesives, as hereinafter described more fully may be used.

In the drawing FIGURE 1 shows, in partial section, a perspective view of a double-walled bag or encasement containing asphalt.

FIGURE 2 is a sectional elevational view of the package shown in FIGURE 1, taken along the line 22.

FIGURE 3 shows, in sectional elevation, a portion of an alternative laminated double film or sheeting to be used in place of the single films of the double-walled container shown in FIGURES l and 2.

Referring now, in detail, to the features shown in FIG- URES 1 and 2, 2 is a container having double film walls 3 and ll of polyolefin sheeting or film with an enclosed air space 4 between the double walls. Asphalt 7 is the contents of the bag 2 which is sealed (usually by thermal means) by means of top seal and by means of bottom seal 6. A laminated double polyolefin film as shown in FIGURE 3 consists of an outer polyolecn film 8 and an inner polyolefin film 9 adhered to one another by means of an adhesive layer or coating 10.

All types of solid or semi-solid (at ambient temperatures) asphalts are contemplated as being packaged by the laminated or double walled encasement polyolefin films herein described. More specifically, some of the standard conventional paving asphalts which may be so packaged are as follows:

The polymers and copolymers of ethylene and/or propylene must have melt indices measured at 230 C. (ASTM D 1238) of less than 12. These are the film grade thermoplastics and, in the case of polyethylene, they generally have a number average molecular weight in excess of 30,000 and, in the case of polypropylene, these film grade polymers have a number average molecular weight generally in excess of 100,000. In the case of the plastic or plastomeric ethylene/ propylene copolymers, it is difiicult to ascribe a precise minimum number average molecular weight because this will vary depending upon the relative amounts of ethylene/ propylene employed in producing the copolymer. Sufiice it to say, however, that the melt index of the ethylene/propylene copolymers, measured at 230 C., must be less than 12 and that the olefinic monomers present in the lesser amount should not exceed of the total olefinic monomeric reaction mixture. All of these polymeric materials are standard articles of commerce and it is not necessary to go into the details of their methods of manufacture in adequately describing the present invention. Suflice it to say that large commercial plants arein operation today and that millions of pounds of these materials in various forms, including the film form, are commercially available.

One of the chief advantages of the use of these particular polymers and copolymers of the mono alpha olefins lies in the fact that there is no necessity or need for separating or attempting to separate the wrapper or bag from its asphaltic contents once the packaged material has been shipped to or near the plant of the ultimate user. The entire package, container and contents, are subjected to sufficiently high melting temperatures to obtain a homogeneous admixture to serve as aggregate binder. The multilayered bags or wrappers generally constitute films of about 2 mils thick although thicker sheetings may be employed particularly where a multi-layered laminate is to be employed or Where two or more non-laminated sheetings are to be employed as an unbonded double walled bag or wrapper for the asphaltic compositions. In preparing laminates, it is possible to use films having a thickness of 1 mil down to 025 mil and to build them up to the desired 2 mil-4 mil thicknesses by multiple layering. As previously mentioned, petroleum resins may be employed as the adhesive serving to adhere or laminate two or more film materials together where it is desired to employ laminated films as the container materials. Other suitable adhesive coatings which are compatible with asphalt and which may be used in preparing filmed sheeting laminates are the following: ethylene-vinyl acetate copolymer containing from 5% to 40% vinyl acetate and prepared by conventional prior known methods (See U.S. Patents 2,200,429 and 2,703,794), without or with from 5 to 25 wt. percent of the final composition being paraffin wax, chloroprene, rubber cements and the like. Extruded polypropylene in film form can be treated electrostatically or by flame oxidation after which a film of polyethylene (extruded) is laid in contact therewith at 550 to 600 F. and thereafter cooled. Such a laminate is suitable to use as bagging material with the polypropylene or ethylenepropylene copolymer layer preferably being in contact with the asphalt. The sheeting in direct contact with the asphalt may be any one of the three above mentioned polymers or copolymers, namely, polyethylene, polypropylene, or the plastic or plastomeric copolymer of ethylene with propylene, preferably polypropylene or the ethylene-propylene copolymer. Other sheetings either in laminated form or as a separate sheet or wall (double or triple walled) of the bag may be of the same material which is in contact with the asphalt or it may be one of the other two mentioned material s. Thus, the inner or contact material may be polyethylene or polypropylene and the outer material may be a film of polypropylene or polyethylene respectively. Similarly, the internal film may be the ethylene/propylene copolymer and the outer material either polyethylene or polypropylene. Double walled containers of polyethylene, polypropylene, or the copolymer may be employed. Polyethylene is best for use in the outer wall since it has the highest strength. The other material has the highest oil resistance and may be used as films of 0.25 mil to 0.5 mil thicknesses. One of the big advantages of the use of these bags lies in the fact that the ultimate user, i.'e., the mixing plant adjacent the site of ultimate placement of the asphalt composition simply has to add the entire bag, wrapper and contents, to a 'melter which-is equipped with an agitator and to maintain the temperature of that melter at a temperature above the softening point of the asphalt and above the softening point of the polyolefinic bagging material so that the wrapper, or bag, and its contents are both reduced to a molten state and thoroughly mixed. To the extent that polyolefin is thus incorporated into the asphalt, its paving properties are altered and improved. This temperature will vary depending upon the softening point of the particular paving or industrial asphalt employed and depending upon the particular olefinic polymer and/or copolymer employed in the wrapper or bag. Generally, temperatures of the order of about 275 F. up to about 550 F. are sufficient to accomplish this desired result. The addition of the olefinic polymers or copolymers to the asphalt tends to lend bonding strength to the asphalt composition. (See U.S. Patents 3,144,423 and 3,144,424 granted Aug. 11, 1964.) As a further aid in the uniform dispersion of the polymers or copolymers into the molten asphalt, it is possible to initially incorporate into the asphalt at the refinery or to incorporate into the plastic polymeric sheeting a small amount of a plasticizer, such as tricresyl phosphate, at least to the extent of its solubility in the asphalt, i.e., up to about 2 wt. percent based on the total admixed bag and contents. This aids in the dissolution or solvating or" the polymeric wrapper or container material into the asphaltic composition at the mixing plant and aids in quickly producing a homogeneous mixture of the bags or Wrappers and their asphaltic contents.

The following examples are given by way of illustration but are not intended to limit the invention thereby.

Example 1 Polyethylene Film Oil Tackiness Package Thickness Transfer Suitability Single Wall, 2 mils Severe. Severe. Unsatisfactory. Single wall, 4 milsd0 Do. Single wall, 6 mils Severe Moderate... Marginal. Double wall, 2-2 mils Moderate... None Satisfactory.

Example 2 A similar grade of paving asphalt as that described in Example 1 was packaged in bags which were made of a laminate of 0.75 mil thickness of polyethylene film or sheeting bonded to a film of polypropylene or" a thickness of 0.25 mil, the two layers being bonded to one another with an adhesive available commercially for various periods of time up to 150 days at temperatures of 110 and 150 F., under a loading of 10 lbs. per square foot. The total thickness of the laminate was approximately 1 mil and only slight tackiness resulted for over twice the storage period used in the case of polyethylene alone as a single walled 2 mil container, which showed severe tackmess.

Having now thus fully described and illustrated the invention, what is desired to be secured by Letters Patent 1. A package consisting essentially of paving asphalt, having a softening point of between about F. and about F., enclosed within a multilayered incasement, each layer being a thin flexible continuous self-sustaining poly alpha olefin film having a melt index below about 12 when measured at 230 C., and being selected from the group consisting of polyethylene, polypropylene and the plastomeric or plastic copolymer of ethylene with propylene, one comonomer being present in an amount of between about 1% and about 10%, the remainder being the other comonomer and wherein the poly alpha olefin becomes, upon heating, homogeneous with the paving asphalt contained therein.

2. The package as in claim 1 wherein the multilayered incasement is a double walled bag, both walls being polyethylene.

3. A package as in claim 1 wherein the incasement is a double walled bag, one layer being of polyethylene and the other layer being a film of the copolymer of ethylene with propylene.

4. A package as in claim 1 wherein the incasement is a double walled bag, one layer being of polypropylene and the other layer being a film of the copolymer of ethylene with propylene.

5. A package as in claim 1 wherein the multilayered incasement is a double walled bag both walls being at least a two-ply laminate, one film layer being polyethylene and the other film layer being ethylene-propylene copolymet.

6. A package as in claim 1 wherein the multilayered incasement is a double walled bag, one wall being polyethylene and the other wall being polypropylene.

7. A package as in claim 1 wherein the incasement is at least a two ply laminate, one layer being polyethylene and the other layer being polypropylene.

8. A package as in claim 3 wherein the laminated films are adhered to each other by means of an adhesive coating.

9. A package as in claim 7 wherein the incasement is a double walled bag both walls being at least a two-ply laminate.

TABLE Type and Thickness l Days Temp, Oil Transfer Tacklness Package Suit- F. ability 1 layer 150 Moderate Slight Satisfactory. 2 layers (double bag) 2g 58 None None Do.

Do 150 150 Trace do D0. Polyethylene:

2 mil, 1 layer 70 150 Severe Severe Unsatisfactory.

2-2 mil, double wall g; }Moderate Very slight Satisfactory.

1 First four runs employed a laminate film (layer) of polyethylene (0. 75 mil thickness) adhered to polypropylene (0.25 mil thickness).

References Cited UNITED STATES PATENTS 2,721,691 10/ 1955 Makrauer 22955 2,762,504 9/1956 Sparks et al. 206-84 2,914,238 11/1959 Clark 206-84 X 2,919,059 12/ 1959 Sporka. 2,956,723 10/ 1960 Tritsch. 2,983,704 5/ 1961 Roedel. 3,204,825 9/ 1965' Underwood 22955 X FOREIGN PATENTS 660,635 4/ 1963 Canada.

JOSEPH R. LECLAIR, Primary Examiner.

THERON E. CONDON, Examiner.

I M. CASKIE, Assistant Examiner.

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