US3470016A - Bitumen-impregnated-foam material - Google Patents

Description

United States Patent M 3,470,016 BITUMEN-IMPREGNATED-FOAM MATERIAL James R. Biles, Athens, and Wendell E. Brennan, Decatur,

Ala., Stephen H. Alexander, St. Louis, Mo., and Edgar E. Hardy, Dayton, Ohio, assignors to Monsanto Company, St. Louis, Mo., a corporation of Delaware No Drawing. Filed Dec. 13, 1965, Ser. No. 513,565 Int. Cl. B4411 1/06; 1332b 5/18 U.S. Cl. 117-76 7 Claims ABSTRACT OF THE DISQLOSURE An article comprised of a bitumen and a foamed plastic having a multicellular structure and reinforced with a fibrous material. The bitumen represents at least 90% by weight of the combined weight of the bitumen and foamed plastic and occupies at least 50% of the free space of the cells of the foamed plastic.

The present invention relates to bituminous compositions. More particularly, the present invention relates to compositions containing a bitumen and a foamed plastic, which compositions are particularly useful as roofing and waterproofing compositions.

One of the major uses of bituminous materials is in roofing compositions. In addition, large quantities of hituminous materials are used in waterproofing barriers for walls and foundations of buildings and as linings for irrigation canals and drainage ditches. In each of these utilities, the bituminous composition used must be characterized by an ability to withstand the temperature and humidity conditions of its environment without cracking, flaking, sagging or flowing. In addition, the bituminous composition must be able to withstand some shifting of the surface to Which it is applied and also must be able to withstand the movement of heavy objects across its surface, particularly from walking or moving equipment on its surface.

Usually, the bituminous compositions used as roofing or as waterproofing materials include a fibrous material such as felt. Such fibrous materials improve the strength and wear resistance of the bituminous composition. However, despite the improvement in the properties required in roofing and waterproofing compositions resulting from inclusion of such fibrous materials, still it is necessary to carefully select rather narrowly defined bituminous materials in order to meet the requirements of use in roofing and waterproofing compositions. Further, there is yet room for substantial improvement in the strength and wear resistance properties of bitumen-containing roofing and waterproofing compositions.

It is an object of the present invention to provide new and useful bituminous compositions and a method for their preparation. Another object of the present invention is to provide new and useful compositions containing a bitumen and a foamed plastic. It is also an object of the present invention to provide new bituminous compositions particularly useful in roofing, waterproofing walls and foundations and in lining irrigation canals and drainage ditches. Another object of the present invention is to provide a method for preparing new compositions containing a bitumen and a urethane foam. A remaining object is to provide new asphalt-urethane foam compositions and a method for their preparation, which compositions are particularly useful in roofing, waterproofing walls and foundations, and lining irrigation canals and drainage ditches. Additional objects will become apparent from the following description of the invention herein described.

The present invention which fulfills these and other 3,470,016 Patented Sept. 30, 1969 objects is, in one embodiment, a composition comprised of a bitumen and a foamed plastic having a multicellular structure and reinforced with a fibrous material, said bitumen representing at least by weight of the total weight of bitumen and foamed plastic, and said bitumen occupying at least 50% of the free space of the cells of said foamed plastic. These compositions have properties which make them particularly useful in roofing and waterproofing compositions. These compositions are more elastic and have greater tensile strength than conventional bituminous roofing and waterproofing compositions of similar weight. In addition, these compositions possess excellent weathering properties. Further, the compositions of the present invention may include a much wider range of less narrowly defined bitumens as the bituminou constituent than may be used in more conventional compositions for similar utilities. The present compositions allow the use of greater quantities of less costly bituminous materials than are commonly used in compositions of similar properties and utility. In addition, because of greater strength and flexibility, the present compositions are easier to apply to the surface to which they are to be applied. Further, the compositions of the present invention may be prepared in greater thicknesses than conventional roofing materials and may replace many layers of such conventional roofing materials.

In another embodiment the present invention comprises a method or" preparing the above-defined composition, said method comprising impregnating a foamed plastic having a multicellular structure and reinforced with a fibrous material, with a bitumen under conditions such as to fill at least 50% of the free space of the cells of said foamed plastic with said bitumen and to cause at least 90% by weight of the combined weight of foamed plastic and bitumen to be said bitumen.

It is further an embodiment of the present invention to impregnate a nonreinforced foamed plastic material having a multicellular structure with a bitumen and then to adhere a fibrous reinforcing material to at least one surface of the resulting bitumen impregnated foamed plastics, said nonreinforced foamed plastic having been impregnated with said bitumen to an extent such that at least 5 0% of the free space within the cells of said foamed plastic is filled by said bitumen and the amount of bitumen in the final composition, including said fibrous reinforcing material, is at least 90% by weight of the combined weight of said foamed plastic and said bitumen. When the fibrous reinforcing material is to be adhered to said foamed plastic after impregnation with the bitumen, the fibrous reinforcing material may be separately impregnated with bitumen or may be impregnated with said bitumen after it is adhered to the bitumen impregnated foamed plastic. In either method, the amount of bitumen used to impregnate the fibrous reinforcing material is taken into account in determining the percent by weight of bitumen present in the final composition.

In order to further describe and particularly to demonstrate the present invention, the following examples are presented. These examples are in no way to be construed as limiting the present invention, however.

Example I A composition was prepared by foaming a urethane on both sides of a sheet of woven nylon yarn to form a finished sheet of about A inch thickness with the woven nylon approximately of equal distances from the outer surfaces of the foamed urethane. The foamed urethane sheet so prepared had a density of 0.06 gram/emf. This sheet was then passed into a molten bath (325 F.) of asphalt, compressed between a series of rollers within said bath to eliminate vapor from the pores or cells of the foam and then withdrawn from the bath after the asphalt had replaced the displaced vapor. After withdrawing the asphalt impregnated urethane foam-nylon yarn sheet, it was allowed to cool back to ambient temperature. The asphalt used was one having a softening point (R&B) of 145 F. and a penetration at 77 F., 100 grams, 5 sec. of 33 min/l and obtained from steam and vacuum distillation and a South Arkansas crude oil and the subsequent air-blowing of the residue. The asphalt impregnated urethane foam had a density of 0.89 grams./ cm. This asphalt impregnated urethane was 93.0% by weight asphalt, 5.7% by weight urethane foam and 1.3% by weight nylon yarn. The cells of the urethane foam were substantially filled with the asphalt.

The composition prepared above was tested for permeation by moisture vapor in accordance with ASTM E9653T, Procedure E, and was found to have very low permeation. The above-described composition of the present invention was found to have high tensile strength and high elongation.

Example II Additional compositions were prepared in accordance with the present invention using the foamed urethanenylon yarn sheet described in Example I. In preparing these additional compositions, three asphalt solutions of asphalt dissolved in a petroleum naphtha of 300360 F. boiling range were prepared. The asphalt solutions contained 50, 65 and 80% by weight of asphalt. The asphalt used was one having a softening point (R8113) of 148 F. and a penetration at 77 F., 100 grams, 5 sec. of 31 mm./ 10. Impregna-tion of the foamed urethane-nylon yarn was accomplished by immersing three separate segments of this material in the three asphalt solutions and drawing a vacuum to eliminate vapor from the pores or cells of the foamed urethane and to cause these pores to be filled with asphalt. Solvent was removed from the composition by drying at elevated temperatures. The compositions of the three asphalt impregnated urethane foam-nylon yarn compositions prepared from the three asphalt solutions were as follows:

Asphalt solution used Composition in weight To demonstrate the criticality of the asphalt concentration in the compositions of the present invention, the above three compositions were subjected to accelerated weathering tests in the Weatherometer (operated according to ASTM D529 62). After weathering 1794.4 hours, the composition containing 81.2% by weight asphalt sparked all over when placed on a metal plate and tested with a high voltage spark gap tester. Further, cracks had de veloped in both the asphalt and urethane foam to the extent that the nylon yarn was clearly visible at scattered points in the test panel and there was evidence of the urethane becoming brittle and easily disbonded from the nylon yarn. In addition, the texture of the panel resembled that of cork and could be peeled off when rubbed. The composition containing 86.5% by weight of asphalt after weathering for the same time period showed similar weathering, but to a lesser degree than the composition containing 81.2% by weight asphalt. The third composition containing 91.8% by weight of asphalt, after weathering for the same time period, was found to be substantially improved over the other two compositions. Only two short cracks were found and there appeared to be no breakdown of adhesion to the nylon yarn and the asphalt impregnated foamed urethane could not be easily rubbed from the nylon yarn and this sample did not have the cork-like texture of the other two compositions.

4 Example III Prepared from 65% lreparcd from 85% asphalt soln. asphalt soln.

Composition in weight percent I II III IV V VI Asphalt 90. 5 90. 3 90. 5 92. 2 93. 5 93. l Urethane 7. 7 7. 9 7. 7 G. 3 5. 3 5. 6 Nylon yarn 1.8 1. 8 1. 8 1. 5 1. 2 1. 3 Vol. percent of foam cell space filled with asphalt 62. 4 61.3 G2. 6 81. 2 94. 0 88.8

To again demonstrate the criticality of the amount of asphalt present in the compositions of the present invention and to also demonstrate the importance of the degree to which the cell space of the foam is filled with asphalt, the above six compositions were tested for moisture vapor permeability according to the method of ASTM E-9653, Procedure E. The results of this test expressed in perms are as follows:

Composition:

I 1.16 II 1.23 III 1.13 IV 0.226 V 0.0905 VI 0.113

These results demonstrate that the higher the concentration of asphalt, the lower the permeability to moisture vapor. Further, these results clearly illustrate the importance of having the pore space of the urethane foam substantially filled where it is desired to prevent moisture vapor transmission through the composition.

The bitumens useful in the compositions of the present invention include various natural and synthetic asphalts, tars and pitches. Particularly useful are petroleum asphalts such as those obtained from California crudes, Mid-Continent crudes and air-blown oils, South Arkanass crudes, Mexican petroleum asphalts, East Texas crudes and the cracked asphalts or pitches obtained as by-product from the cracking of hydrocarbons or petroleum crudes or fractions to obtain gasoline or gaseous olefins, etc. Other bituminous materials such as coal tar, wood tar and pitches obtained from various industrial processes such as fatty acid pitches, may be used though less desired.

The bitumen of the compositions of the present invention may be one subjected to any of the commonly used refining or treating processes such as distillation, steam or vacuum reduction, air-blowing, either catalytica-lly or non-catalytically, solvent extraction, etc. Bitumens also include the cutback bitumens, i.e., those bitumens dissolved in a volatile solvent such as kerosene, solvent naphtha, toluene, benzene, petroline, etc., as well as asphaltic emulsions.

The particularly useful bitumens for the present compositions are the asphalts, particularly those obtained from South Arkansas and East Texas crudes. Such asphalts may or may not be air-blown and if air-blown, may have been blown either catalytically or noncatalytically. In addition, such asphalts may be obtained by atmospheric distillation and/or vacuum reduction or steam reduction and/or propane precipitation. These use-- ful asphalts usually have a softening point (R. & B.) within the range of to 220 F., preferably within the.

range of 120 to 200 F., a penetration at 77 F., 100 grams, 5 sec. of to 200 mm./10, preferably to 100 mm./ 10, a Saybolt Furol viscosity of no more than 500 seconds at 375 F. and preferably no more than 300 seconds and a flash point of no less than 400 R, preferably 450 F. When the compositions are to be used as roofing compositions, it is preferred that the asphalt be one of 100 to 190 F. softening point, to 100 mm./l0 penetration at 77 F., 100 grams, 5 sec., a maximum Saybolt Furol viscosity of 300 seconds at 375 F. and have a flash point of no less than 425 F.

The amount of bitumen present in the present compositions is generally greater than 90% by weight of the combined weight of the bitumen and the foamed plastics. Preferably, the amount is greater than 92.0% by weight.

The foamed plastics useful in the compositions of the present invention include the foamed polyurethanes, foamed polyvinyls, foamed polyvinyl aromatics and polyvinyl halides and acetatesand in general, any plastic material having a foamed structure. The preferred foamed plastics, however, are the polyurethane foams. The foam structure of the foamed plastic has open pores or cells in at least its outer layers. Preferably, however, the foamed plastic has open pores or cells throughout its body in order that the bitumen may be subsantially uniformly distributed through the foamed plastic. The plastic foam is preferably one with good elasticity. The choice of the particular foam used and its particular characteristics will vary depending upon the intended application of the final composition.

The fibrous reinforcing materials of the present invention include a wide variety of materials and may vary considerably depending on the intended use of the final composition. These materials may be in the form of a sheet of woven fibres or a sheet of pressed fibres. It is not necessary that the fibrous membrane be in the form of a sheet, but rather it may be comprised of many strands of yarn or synthetic fibres preferably aligned in a single plane and either parallel or randomized with relation to one another. Fibrous reinforcing materials also include molded or extruded sheets or materials which impart reinforcement to the foamed plastics. It is only necessary that the fibrous reinforcing materials provide reinforcement for the plastic foam. The fibrous reinforcing material is preferably one consisting of a sheet of woven nylon yarn. The fibrous reinforcing material is most often one of such construction as to allow a minimum of 5% elongation and preferably is one having greater than 20% elongation.

The position of the fibrous reinforcing material with respect to the plastic foam may vary depending on the future use of the resulting composition. The fibrous material may be adhered to either or both flat outer surfaces of the foam or positioned internally Within a sheet of plastic foam. For roofing compositions, it is preferred that the fibrous material be placed within the foamed plastic substantially equidistant from the outer surfaces thereof.

The method of adhering the fibrous reinforcing material to the foamed plastic is usually through the natural adhesion of the foamed plastic to the fibrous material. Most plastic foams may be gently heated and the fibrous material adequately attached. In addition, solvents may be used to cause the surface of the foamed plastic to become sufficiently tacky to cause the fibrous material to adhere thereto. Also, and particularly useful, the composition often may be prepared by foaming the plastic on the surface of the fibrous material. Various adhesives may be used to adhere the fibrous material to the foamed plastic though some care in choice is necessary to avoid adhesives which may form an impervious layer between the foamed plastic and the fibrous material. Preparation of fibrous reinforced plastic foams in which the fibrous reinforcing is contained within the plastic foam rather than on the external surfaces of the plastic foam is by substantially the same methods employed for preparing plastic foams having the fibrous reinforcing on an external surface. A particularly useful means of such preparation is that illustrated in Examples I, II and III wherein a plastic is foamed on each side of fibrous ma terial. In addition, fibrous reinforcing material may be adhered to an external surface of a foamed plastic by any of the other means described above and then a second sheet of foamed plastic adhered to the opposite side of the fibrous material.

Impregnation of the fibrous reinforced foamed plastic composition with the bitumen may be carried out in a number of ways. Within wide limits, the means of impregnation is not particularly critical. However, the means should be such as to cause at least 50% of the available pore or cell free space to be filled with bitumen and preferably is such as to cause at least of the available pore or cell free space to be filled with bitumen. A very useful means of impregnating the plastic foam with the bitumen is that illustrated in Example I above. In such method, the plastic foam is passed through bitumen which has been liquified either by heating or by the use of solvents, the foam passed through rollers to squeeze out vapor from the pores or cells of the foam, bitumen being drawn into the evacuated pores as the foam expands on leaving the rollers, and then withdrawing the bitumen impregnated plastic foam and allowing it to cool back to normal. temperatures and/ or dry. Another useful method of impregnating the plastic foam with the bitumen is illustrated in Examples II and III above. This method comprises dissolving the bitumen in a suitable solvent, immersing the foamed plastic in the resulting solution and then drawing a vacuum on the immersed material to remove vapor from the pores which are then filled by the bitumen solution. Excess solvent is removed either by increasing the vacuum or by gentle heating or merely by allowing a long drying period for the composition. Suitable solvents for the bitumen include any of the conventional cutback vehicles or solvents above defined. The preferred solvent is a petroleum naphtha of a boiling range within about 200 to 400 F. In addition to the above methods, many others will readily present themselves to those skilled in the art and may be practiced without departing from the spirit or scope of the present invention. So long as the method for impregnation results in substantially filling the pores or cells of the foamed plastic without causing significant destruction or injury to the foamed structure, the method amy be used to prepare the compositions of the present invention.

The compositions of the present invention are particularly useful as roofing compositions. In addition, these compositions are quite useful in waterproofing walls and foundations of buildings and in lining the sides and bottoms of open ponds, irrigation canals and drainage ditches. Further, these compositions are useful in coating objects which are subjected to considerable weathering.

What is claimed is:

1. An article comprised of foamed plastic having a multicellular structure and reinforced with a fibrous material, said foamed plastic impregnated with a bitumen, said bitumen representing greater than by weight of the combined weight of said bitumen and said foamed plastic and said bitumen occupying at least 50% of the free space of the cells of said foamed plastic.

2. The article of claim 1 wherein said bitumen is an asphalt.

3. The article of claim 2 wherein said asphalt is one having a softening point of 8 0 to 220 F., a penetration at 77 F., grams, 5 sec. of 10 to 200 mm./l0, a Saybolt viscosity at 375 F. of less than 500 seconds and a flash point of at least 400 F.

4. The article of claim 1 wherein said foamed plastic is a polyurethane foam and said fibrous material is a woven nylon yarn.

5. The article of claim 1 wherein said fibrous material 2,972,554 2/1961 Muskat et a1. 117-98 X is contained within said foamed plastic. 2,993,813 7/ 1961 Tischbein.

6. The article of claim 1 wherein said bitumen occupies 3,222,208 12/ 1965 Bertollo 11763 at least 85% of the free space Within said cells of said 3,257,336 6/1966 Levy et a1. 2602.5 foamed plastic material. 5 3,278,329 10/ 1966 Wiczer.

7. The article of claim 1 wherein said bitumen com- 3,326,810 6/ 1967 Dolan et al.

prises at least 92.0% by Weight of said article.

WILLIAM D. MARTIN, Primary Examiner References Cited R. HUSACK, Assistant Examiner UNITED STATES PATENTS 10 2,888,407 5/1959 Cooper et al. 2602.5 2,964,424 12/1960 Mast 117-98 117-92, 98, 138.8; 161-92, 160, 161, 190; 260-2.5