BACKGROUND MATERIAL BACKGROUND OF THE INVENTION This invention relates to roofing material, and in particular to roof shingles having a novelty backing that provides improved features such as, for example, resistance to damage caused by hail. The roofing material has a front upper surface, at least a part of which is contemplated to be exposed to the weather, and a lower rear surface facing in the opposite direction to the upper surface. Traditionally, the back surface, not exposed to the weather, of roofing material, such as shingles, has been covered with finely ground ("fine") mineral material so that the asphalt coating does not adhere to the adjacent roofing material when is packed for transport and storage. Such finely divided materials include mica flakes, copper slag, coal slag, sand, talc, and silica dust. In many regions, roofing materials for buildings, especially shingles in residential buildings, are damaged by hail. The damage is caused by the impact of the hail on the shingles and results in cracks, tears, ruptures, visible or imperceptible damage to the structure of the shingles that make shingles less resistant to elements such as wind, rain, snow and ice. Frequently, such damage requires the costly replacement of roofing materials in order to prevent the elements from entering the building. U.S. Patent No. 6,341,462 B2 to Kiik et al. Discloses a roofing material with improved resistance to hail damage having a backing layer that absorbs the energy adhered to its bottom surface. The backing layer of US Patent No. 6,341,462 comprises fiber components and bonding components with a combined weight within a range of 0.227 kilograms to 2.27 kilograms per square (9.27 square meters) [(between 0.5 and 5 pounds per square (100 square feet)] of shingle material such that the exposed portion of a shingle manufactured in accordance with US Patent No. 6,341,462 appears more substantial and is in fact visibly thicker prior to application than products made without the coating BACKGROUND It is an object of the present invention to provide roofing materials, especially shingles, with a reduced susceptibility to damage during hailstorms, and yet light and simple to manufacture and pack using conventional equipment COMPENDIUM OF THE INVENTION In accordance with the present invention, the wear of roofing materials such as shingles improves by application over the men a part of its rear surface, ie the surface not exposed to the weather, of a thin layer of plastic, such as, for example, thermoplastic. In a preferred embodiment, the backing layer has a thickness of approximately 13 micrometers (0.5 mil) and comprises essentially rolled polypropylene material, pellets, scales, fibers, and / or other suitable polypropylene material. DETAILED DESCRIPTION OF THE INVENTION Conventional materials for asphalt ceilings, including shingles, are manufactured using a continuous process in which a fibrous base fabric, such as a roof felt sheet or a fiberglass mat is impregnated with a bituminous material and then applied on one or both surfaces with a bituminous weather resistant material. The bituminous coating usually contains a mineral filler such as slate dust or limestone powder. It can be laminated more than a fibrous sheet within several bituminous layers. Usually, a suitable granular material, such as slate granules or mineral finishing material, is applied to the bituminous coating on the surface that will be exposed to the weather. Finely divided materials such as mica flakestalc, silica powder or the like are adhered on the non-exposed surface of the roof shingles in order to avoid adhesion of the adjacent layers of roofing material in packaging. Alternatively, in accordance with that disclosed in US Patent No. 6,341,462, a backing layer comprising filler and binder materials may be adhered on the surface not exposed to the weather of the roof shingle instead of the fines for the purpose. of avoiding the adhesion of adjacent roofing materials and to offer additional strength and other beneficial physical properties. In the present invention, at least a part of the fines or composite backing layer is replaced by a thin layer of plastic or re-melted plastic which prevents adhesion of adjacent packed roofing materials, is simple to manufacture, lightweight, almost it does not increase the overall thickness of the roofing material and yet it improves the physical properties of the roofing material by, among other things, decreasing its susceptibility to hail damage. In one embodiment, at least about 13 micrometers (0.5 mil) of re-melted polypropylene rolled material, pellets, flakes, fibers and / or other suitable polypropylene material is applied to the back surface of the roofing material. More preferably, a layer of approximately 76-102 microns (3-4 mils) is applied. The weight increase of said polypropylene backing is therefore only about 0.91 kilograms per square (2 pounds per square), which is less than the weight of conventional roofing materials with a fine backing. A backing in accordance with the present invention formed by employing a greater thickness of polypropylene or a sufficient thickness of another plastic will have a weight comparable or poss greater than conventional roofing materials. According to its composition and thickness, the backing of the present invention can have a weight comprised between 0.045 and 4.54 kilograms / square (0.1 and 10 pounds / square). As noted above, one embodiment of the backing of the present invention can be formed using polypropylene in one or more of different ways. In addition to those mentioned above, spun polypropylene can also be used. Additional embodiments may employ different suitable polyolefins or copolymers comprising at least one polyolefin: for example polyethylene, polyvinyl chloride, ethylene-vinyl acetate, acrylonitrile-butadiene-styrene
("ABS"), acetal, acetate, butyrate, nylon, polyalloy, polycarbonate, polystyrene, styrene-butadiene copolymers, polysulfone, propionate or polyvinyl chloride. In other embodiments, thermosetting materials or elastic materials, such as ethylene-propylene-diene monomer rubber sheets ("EPDM"), high density silicone rubber, thermoplastic rubber, elastomers, or curable and curable acrylics may be used. Still other embodiments may employ laminates or multiple layers optimized to provide the adhesive, mechanical and other desired properties for the backing layer. For example, the backing may comprise a first layer of spun polypropylene coated with one or more layers of polyethylene or a layer of polypropylene spun with one or more layers of polyethylene laminated therein. Alternatively, the backing may comprise a nonwoven polyethylene terephthalate mat "C" PET "coated with polyethylene. The backing material of the present invention is applied on the face of the backside of the shingle instead of the fines, granules or other standard backing material conventionally applied in the slab drum stage during the manufacture of the shingles. As such, the shingles of the present invention can be manufactured using a standard line where asphalt is applied on the moving fabric and mineral granules are dropped on the upper surface of the fabric coated with hot asphalt. A preferred application technique for the backing of the present invention is similar to current industry practice for applying fines, granules or other standard backing material, except that plastic pellets, flakes and / or fibers can be replaced instead of fine, granules or other standard backing material. However, any other suitable method of application may be used, including application in one or several layers of extruded or pre-cast plastic on the shingle. In a preferred embodiment, the backing of the present invention is formed from at least about 13 micrometers (0.5 mil) of polypropylene, i.e. preferably more than 51 micrometers (two thousandths of an inch) of polypropylene, and most especially, 72 to 102 micrometers (three to four thousandths of an inch) of polypropylene. Since polypropylene has a melting point of about 350 ° F (177 ° C), while the asphalt coating on moving fabric is typically maintained at a temperature of about 400 ° F (204 ° C) during manufacture of shingles, certain rolled polypropylene materials, pellets, flakes and / or fibers melt in contact with the asphalt coating, thereby forming a melted layer of substantially uniform thickness covering part or all of the asphalt surface. As the roofing material coated with polypropylene is moved through the production process, the melted polypropylene is cooled to form a continuous resolidified layer of substantially uniform composition and thickness adhered to the backside of the shingle. Pigments and other additives may be combined with the polypropylene, as required, preferably in pellet form, to change the color of the polypropylene layer and to provide increased resistance to UV damage, even though the black color typically used to minimize Edge visibility is inherently a good UV light inhibitor. In the process described above to produce a roofing material with polypropylene backing, suitable plastics with a melting point below about 204 ° C (400 ° F) can be replaced or mixed with the polypropylene roll material, pellets, flakes and / or fibers. In addition, plastic materials, with melting points above 204 ° C (400 ° F), such as EDPM, or certain polypropylene materials with higher melting points, can be used to the extent that the melted asphalt adheres to such materials at the typical manufacturing temperature of approximately above 204 ° C (400 ° F). It is known in the art to manufacture roof shingles with an adhesive or seal placed in the upper edge region of the upper surface of the shingle such that, in an assembled roof comprising several rows of shingles, the lower edges of the row Next of shingles splice and cover the adhesive, which consequently results in adhesion between the two rows. Alternatively, it is known to manufacture shingles with the adhesive on the lower portion of the rear surface of the shingle in order to obtain the same result. In the present invention, to maintain good adhesion, the shingles may have an adhesion or seal region in the lower portion of the back surface of the shingle that does not include the backing material of the present invention. Instead, the adhesion region or seal is covered with conventional fines. The shingles manufactured with the polypropylene backing described here have a better tear strength than the 1800-2100 grams that is typical of standard shingles with fine backing. The tear resistance of the polypropylene backed shingles is typically more than 3000 grams at the point of manufacture which is comparable or better with that obtained in the case of shingles manufactured with a comparable thickness of the composite backing of the North American Patent. No. 6,341,462. The shingles of the present invention are also less susceptible to breakages by machines and fractures and tears during field application, that is, they better tolerate the rigors of shingle installation than conventional shingles. In addition, the shingles of the present invention offer improved impact resistance despite being a lightweight product, offer improved nail holding capacity and maintain their structural integrity at elevated temperatures. Also, the polypropylene sheet applied on the back of the shingle is waterproof. Thus, a seal resistant to improved impacts against water penetration is offered. The backing according to the present invention described herein can be applied to any design or formulation of roofing material such as for example roofing materials for accumulation, roofing material in rolls and products in modified rolls, but is especially effective in the case of a backing of shingles. The shingles manufactured with said backing that partially or totally cover its lower surface, present improved physical properties even when the internal composition of the shingle remains unchanged. In contrast to the shingles fabricated using the backing layer of US Patent No. 6,341,462, the plastic backed shingles described herein are no more substantial than the products made with a backing of fine sand, and therefore maintain their familiar handling and minimize the need for adjustments to pack. EXAMPLES The conventional Capstone® and Rised Profile® shingles manufactured by Elk Premium Building Products, Inc. were prepared using either mat numbers 1.7 or 2.3, with mat base weights of 0.083 and 0.11 kg / m2 (1.7 and 2.3 lb / 100). square feet), respectively, and comprising 15, 20 or 100% formula FLX ™ and a propylene backing of 51-102 micrometers (2-4 mils), where FLX ™ is a reserved asphalt coating developed by Elk that offers improved handling and resistance. Minor amounts of FLX ™ were used in the samples having the support of the present invention. The Raised Profile® and Domain Winslow® shingles manufactured by Elk were also tested without the support of the present invention for comparative purposes. The roll polypropylene manufactured by DEKU Kunststoff GmbH was used to manufacture the coatings of the present invention. Fire and impact tests were carried out on these samples with polypropylene backing, as shown in Tables 1 and 2, respectively. The fire tests shown in tables 1 were carried out in accordance with the ASTM E108 / UL 790 Class A burnt specifications. The time indicated in the final column is the time in minutes when the combustion stopped completely
(passes) on the bottom side of the floor lit (fails). The impact test shown in Figure 2 was performed in accordance with UL 2290, Class 4. As noted above, standard shingles manufactured by Elk were also tested for comparative purposes. Tables 1 and 2, below show the results of the fire and impact tests, respectively, and demonstrate the comparable or improved performance of the shingles of the present invention in comparison with standard shingles. TABLE 1 Test # Product FLX Mat% Granules
1 Capstone 1.7 20 Slate
2 Capstone 2.3 20 Slate
3 Raised Profile 2.3 100 Standard
4 Capstone 2.3 15 Standard
Capstone 1.7 15 Standard
6 Raised Profile 1.7 20 Standard
7 Raised Profile 1.7 20 Standard (Continuation Table 1) Test # Backrest Backup Time (minutes) / Result
1 4 thousand PP 102 μ PP 44 / Pass 2 4 thousand PP 102 μm PP 40 / Pass 3 Standard Standard 39 / Fail 4 4 mil PP 102 μm PP 37 / Pass 5 4 mil PP 102 μm PP 40 / Pass 6 3 thousand PP 76 μm PP 42 / Pass 7 3 thousand PP 76 μm PP 40 / Pass TABLE 2 Test # Product Mat FLX% Granules 1 Capstone 1.7 15 Standard
2 Capstone 2.3 15 Standard
3 Capstone 1.7 15 Standard
4 Capstone 2.3 15 Standard
Capstone 2.3 20 Slate
6 Capstone 1.7 20 Slate
7 Capstone 2.3 20 Slate
8 Capstone 1.7 20 Slate
9 D. Winslow 2.3 100 Standard
Raised Profile 2.3 100 Standard
11 Raised Profile 2.3 20 Standard
12 Raised Profile 1.7 20 Standard
13 Raised Profile 2.3 20 Standard
14 Raised Profile 1.7 20 Standard
Capstone 1.7 15 Standard
16 Raised Profile 1.7 20 Standard
(Continuation Table 1) Test # Backup Back Result 1 3 thousand PP 76 | um PP Pass 2 3 thousand PP 76 | Lim PP Passes 3 4 thousand PP 102 μm PP Passes 4 4 thousand PP 102 μm PP Passes 5 3 thousand PP 76 μm PP Passes 6 4 thousand PP 102 μm PP Passes 7 4 thousand PP 102 μm PP Passes 8 3 thousand PP 76 μm PP Pass 9 Standard Standard Pass 10 Standard Standard Fail 11 4 mil PP 102 μm PP Pass 12 4 thousand PP 102 μm PP Pass 13 3 thousand PP 76 μm PP Pass 14 3 thousand PP 76 μm PP Pass 15 2 thousand PP 51 μm PP Pass 16 2 mil PP μm PP Fail It will be understood that the foregoing description and examples are illustrative and that other compositions than those described above can be used as backup while still using the principles that form the basis of the present invention. For example, plastics other than polypropylene having an adequate melting temperature and satisfactory mechanical properties can be used to formulate the backing layer. In addition, the backing layer may consist of a combination of polypropylene and other suitable plastics. In addition, the backing layer can be applied to various types of roofing products.