It is known in the shingle art that today's shingles are generally made of a base mat of fibrous construction, most usually of fiberglass construction, that is impregnated with an asphaltic material. The asphaltic material, generally bitumen, of some formulation is disposed on the upper surface of the base mat, and serves to adhere a layer of mineral granules into the asphaltic material on the upper surface of the base mat. Generally such occurs over the entirety of the upper surface of the shingle, but, such mineral granules can, if desired, be applied only to a visible portion of the upper surface of the shingle, to be visible in the installed condition, and to be subject to elements of weather in the installed condition.
Generally, the rear or lower surface of the shingle also has a layer of asphaltic material, and usually has a fine layer of mineral granules, such as sand, talc, mica, or other mineral granules disposed on the lower surface of the shingle.
It has been found that when shingles that have been installed on a roof are subjected to various kinds of impacts, such as falling tree branches, workman walking on the shingles, or hail stones striking the shingles, especially during cold weather conditions, cracks can develop in the lower surface of the shingle as a result of such impacts.
The present invention is directed to an impact resistant shingle, in which an asphaltic material impregnates the base mat of the shingle and the upper surface of the shingle, but wherein an additional layer of a modified asphaltic material, having greater ability to resist cracking than that of the principal asphaltic material and being softer than the principal asphaltic material, is provided, such that the softer asphaltic material is on the rear surface of the shingle that faces the roof on which the shingle is to be applied. When impacts from hail stones, tree branches, walking, or any other impacts are applied against an upper surface of a shingle that is installed on the roof, the softer asphaltic material on the rear surface of the shingle provides a means for dissipating at least some of the impact, whereby crack formation on the lower surface of the shingle is avoided. The modified asphaltic material should have the ability to dissipate mechanical energy. A polymer modified asphalt can have such ability, such that it can resist cracking because it yields or flexes when sharply struck, rather than fracturing.
Accordingly, it is a primary object of this invention to provide a shingle having a softer, impact-resistant layer of modified asphaltic material on its lower surface, that has a greater ability to resist cracking and a greater ability to dissipate energy under conditions in which the upper surface of the shingle is subjected to impact, than the other asphaltic material that is used in the manufacture of the shingle.
It is another object of this invention to accomplish the above object, wherein a layer of reinforcing material is applied to the rear surface of the shingle.
Other objects and advantages of the present invention will be readily apparent to those skilled in the art from the reading of the following brief descriptions of the drawing figures, the detailed descriptions of the preferred embodiments, and the appended claims.
Thus, the present invention is directed toward providing a modified asphaltic material on the lower surface of the shingle, below the base mat, and preferably just above or below the layer of sand, talc, mica or other fine mineral application to the shingle or an application of a fabric, paper, film, scrim or the like, such that the asphaltic material applied to the lower surface of the shingle, being softer, has an ability to resist cracking and an ability to dissipate energy to a greater extent than the asphaltic material that generally comprises most or all of the asphaltic material used in the rest of the shingle.
Referring now to the drawings in detail, reference is first made to
The upper headlap portion 11 is that which is disposed above the upper ends of the slotted openings 14. Left and right edges 15 and 16, respectively, of the shingle 10 have partial cut-outs 15a and 16a, respectively, such that when shingles 10 are aligned left-to-right, portions of slotted openings 15a and 16a will come together forming full slotted openings.
With reference to the shingle of
Irrespective of whether the asphaltic materials 18 and 20 are comprised of a single layer, or of multiple layers, there will normally be disposed on the upper surface of the shingle, a layer of mineral granules 21, which can, if desired, serve to deflect heat, infrared radiation, and ultraviolet rays, and which can provide a desired color or pigmentation to the shingle 10.
Below the asphaltic impregnated mat 17, 18, there is provided an additional layer of asphaltic material that is a modified asphaltic material, designated by the numeral 22. The asphaltic material layer 22 is asphaltic material that is modified relative to the asphaltic materials 18, 20, to be softer, having greater ability than the asphaltic material 18, 20 to dissipate energy and resist cracking at the temperatures normally encountered on a roof, regardless of the ambient weather conditions, and regardless of the climate in which the roof is disposed. The softness of the softer or modified asphaltic material 22 can also be referred to as having a lower elastic modulus than that of the asphaltic materials 18, 20.
The layer 22 of modified asphaltic material can be provided directly to the asphalt impregnated mat 18, or to another intermediate coating of asphaltic material that has been applied to the impregnated mat 18, via lick-on, roll-on, fused powder-coating or spray-on techniques, or otherwise, as may be desired. More than one impact resistant layer or a number of dissipative layers 22 may be used.
Preferably, the layer 22 of modified asphaltic material underlies the entire lower area of the shingle 10, or at least underlies the entire exposed portion of the shingle.
The modified asphaltic material of layer 22 should not be so soft as to create problems of sticking to an adjacent shingle when shingles are stacked together under warm conditions; however, such a concern, should it arise, could be alleviated by a layer 23 of fine granules, such as sand, talc, mica or the like, or alternatively, a release paper, or liner 23a, other parting agent or layer of fabric, paper, plastic film or the like optionally applied beneath the layer 22, for assuring separation between adjacent stacked shingles. The layer 23 or 23a could be permanently or temporarily adhered thereto. The layer 22 of modified asphaltic material can optionally have self-adhesive properties for allowing the product to be adhered to a roofing substrate. In such an embodiment, the layer 22 will preferably be provided with a release paper or tape 23a, or other parting agent, to allow stacking of the shingles prior to adhering them to a roofing substrate, after removal of the release agent to expose the self-adhesive layer 22.
The modified asphaltic material of layer 22 will preferably have a finite yield point and viscosity that is sufficiently high that the material 22 does not flow when in a packaged state, nor when shingles 10 are installed on a steep-sloped roof in hot, sunny weather when they can be subjected to internal or surface temperatures in the range of 140° F. to 180° F.
In the present invention, the modified asphaltic material 22 preferably has greater elongation or extensibility than the material 18. The improved elongation is preferably exhibited even at low temperatures, such as, for example, 30° F. The improved elongation can be a result of the presence of additives which also enhance the ductility at low temperatures and contribute greater resistance to changes in properties as a function of time or temperature than the asphaltic material 18. Preferably, the elongation of the modified asphaltic material 22 is at least two percent, even after extensive exterior exposure, such as that simulated by accelerated ageing carried out by storing shingles made with the modified asphaltic material at 158° F. for at least 10 weeks.
Preferably, however, the modified asphaltic material is not so soft that its penetration at 77° F. is greater than about 150 dmm, as measured according to ASTM D-5. Further, it is preferred that the lower surface of the modified asphaltic material be non-adhesive at ambient temperatures, reducing the likelihood that the improved shingles will become stuck together during shipment and prior to installation, or that the modified asphaltic material will become dislodged by handling during installation or subsequently thereto. Optionally, when a roofing product having self-adhesive properties in the modified asphalt material is desired, a removable or peelable release liner in film or sheet form may be applied to the lower surface of the shingle, so as to prevent sticking together of the shingles during shipment or prior to installation, and subsequently removed when applying the roofing product to a roof substrate.
It is preferred that enhanced temperature elongation be achieved by including in the modified asphaltic material a composition comprising one or more additives selected from elastomers, plasticizers, and resins, and blends thereof. Preferably, the elastomer is selected from natural rubber and thermoplastic elastomers, including styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, and styrene-ethylene-butadiene-styrene block copolymer. The formulation can also include one or more antioxidants, and additional components such as oils.
The modified asphaltic material has greater elongation at low temperatures, such as about 32° F., than the asphaltic material 18 and retains an elongation at 32° F. of at least two percent even after years of exterior exposure, such that the shingle 10 shows no cracking under impact.
The modified asphaltic material 22 may also have a lower modulus, especially at low temperatures, than the asphaltic material 18. That is, the modified asphaltic material is more extensible, as measured for example by the absence of cracking under stress or impact conditions in which the material 18 would crack. In particular, the modified asphaltic material 22 preferably has an elongation at break at low temperature, such as at 30° F., of at least two percent, even after accelerated ageing simulating years of exterior exposure, such as at least ten weeks of storage at 158° F. The modified asphaltic material will also be initially softer or have a lower initial modulus than the material 18, as measured for example by a higher penetration, particularly at higher temperatures. However, in non-self-adhesive applications, the modified asphaltic material 22 is preferably not so soft so as to be tacky or adhesive under ambient conditions, and preferably is not so soft as to “scuff” or suffer mechanical damage from handling during installation.
Under actual exterior exposure or simulated exterior exposure by accelerated ageing, it is often found that the modulus of asphaltic materials tends to increase such that the material becomes harder. The increase in modulus is often accompanied by a decrease in extensibility or elongation. As “toughness” conventionally refers to the area under a stress-strain curve, a material which requires increasing stress to attain a fixed strain as it ages can be said to be “tougher”. In the present invention, the modified asphaltic material 22 can become tougher as it ages, provided it retains the extensibility to provide an elongation at break of at least two percent.
Preferably, the enhanced extensibility is obtained by mixing an additive, a preblended admixture, or several additives with the same type of asphaltic material used for the asphaltic coating 18, and using this as the modified asphaltic material 22. For example, the material 18 can be a standard coating-grade asphalt (softening point 200° F.-240° F.), and the modified asphaltic material 22 can be prepared by mixing a jelly-like premixed asphalt modifier, such as those blends comprising from about 30 percent to 70 percent by weight of a thermoplastic block copolymer, the remainder comprising plasticizers, oils, antioxidants and the like to promote polymer/asphalt compatibility and low temperature flexibility. Examples of such asphalt modifying compositions include but are not limited to those sold by the Chemseco Division of Sika Corporation (Kansas City, Mo.) under the Sikamod™ trademark. The modifying compositions are preferably blended with the steep or coating grade asphalt at a temperature between about 300° F. and 400° F., with agitation sufficient to produce a homogeneous mixture. The choice of asphalt could also include an oxidized straight run type of asphalt that could be modified with a thermoplastic polymer.
Examples of polymeric materials which can be used include that which are known to improve the physical, low temperature, and durability performance characteristics of asphalt, such as atactic polypropylene (APP), isotactic polypropylene (IPP), styrene-butadiene rubber (SBS), chloroprene rubber (CR), natural and reclaimed rubbers, butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), isoprene rubber (IR), styrene-polyisoprene (SI), butyl rubber, ethylene propylene rubber (EPR), ethylene propylene diene monomer rubber (EPDM), polyisobutylene (PIB), chlorinated polyethylene (CPE), styrene ethylene-butylene-styrene (SEBS), and vinylacetate/polyethylene (EVA). Preferably a thermoplastic elastomer, such as a block copolymer of polystyrene, polybutadiene, and polystyrene blocks is employed.
Plasticizers may be selected from the group consisting of petroleum-derived oils, phthalate esters (or their derivatives) and mellitates. Various petroleum resins, polyolefins, rosin (or its derivatives,) tall oil, terpene and coumarone-indene resins can also be employed.
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The shingle 110, on its lower surface, is provided with a wind and/or crack-resistant reinforcement layer 50. The layer 50 may comprise a scrim, or thin fabric, or it may be comprised of a plastic film, paper, parchment or foil. In the case of a scrim, the scrim could be knitted, woven, non-woven, laminated scrim or the like. In the embodiment shown in
The reinforcement layer 50 of scrim or other material will ordinarily not be coated on its lower surface with a bitumen or other asphaltic material, nor will it have granules applied thereto, such that any filaments of the reinforcing material 50, especially those extending vertically as shown in
The reinforcement material 50 may be comprised of various compositions other than fiberglass, such as polyester, and/or nylon, and the reinforcement 50 may either be slightly embedded in the asphaltic layer 44 on the rear of the shingle 110, or may be adhered to the rear of the shingle by an additional post-applied thin layer of asphaltic or non-asphaltic adhesive.
The asphaltic material that comprises the layers 22 and 44 may be constructed in accordance with the second asphaltic binder disclosed in U.S. Pat. No. 5,347,785, or as is the second asphaltic binder or modified asphalt as disclosed in U.S. Pat. No. 5,488,807, the complete disclosures of each of which are herein incorporated by reference, so long as they are in accordance with the above-mentioned characteristics.
Alternatively, the asphaltic material 22, 44, may be constructed of any other formulation that meets energy dissipation and crack resistant conditions desired when the front surface of the shingle is subjected to impact, so long as it is in accordance with the above-mentioned characteristics.
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In accordance with this invention, it will also be seen that there is provided a method of making an impact resistant roof covering system. In accordance with such a method, a shingle is provided having a first asphaltic material that has an elasticity as determined by a first level of softness and a first level of elongation at break. A layer of a second asphaltic material that has a second softness that is softer than the softness of the first asphaltic material, and which has a second elongation at break that is greater than the elongation at break of the first asphaltic material. The second asphaltic material is applied to a roof substrate, and thereafter the shingle is applied to the roof substrate. Alternatively, the second asphaltic material can be applied to the lower surface of the shingle prior to applying the shingle to the roof substrate.
It will be apparent from the foregoing that various modifications may be made in the details of construction, as well as in the use and operation of the present invention, all within the spirit and scope of the invention, as claimed.
This is a continuation-in-part of U.S. application Ser. No. 10/871,911, filed Jun. 18, 2004, which in turn is a continuation of Ser. No. 10/288,747, filed Nov. 6, 2002, the complete disclosures both of which is herein incorporated by reference.
Number | Date | Country | |
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Parent | 10288747 | Nov 2002 | US |
Child | 10871911 | Jun 2004 | US |
Number | Date | Country | |
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Parent | 10871911 | Jun 2004 | US |
Child | 11021573 | Dec 2004 | US |