CA2254133A1

CA2254133A1 - Epdm-based roofing shingle compositions

Info

Publication number: CA2254133A1
Application number: CA002254133A
Authority: CA
Inventors: James A. Davis; George G. Furman; Jerry C. Rose
Original assignee: Bridgestone Firestone Inc
Current assignee: Bridgestone Firestone Inc
Priority date: 1998-11-13
Filing date: 1998-11-13
Publication date: 2000-05-13

Abstract

A roof covering element for sloped roofs, e.g., a roofing shingle, comprising 100 parts by weight of at (east one ethylene-propylene-diene terpolymer, from about 50 to 600 parts by weight of a filler selected from the groups consisting of reinforcing and non-reinforcing materials and mixtures thereof per 100 parts of an EPDM terpolymer, and from 0 to about 120 parts by weight of at least one impact modifying polymer, per 100 parts by weight ethylene-propylene-diene terpolymer, the covering element having an unaged Shore "A" hardness at about 23°C of at least 70, and more preferably, a limiting oxygen index (LOI) of at least 30 percent oxygen when tested in accordance with ASTM D2863-91. The use of fire retardant additives is also desirable.

Description

9707045(176) 1 EPDM-BASED ROOFING SHINGLE COMPOSITIONS
TECHNICAL FIELD
This invention relates generally to covering elements, preferably for roofs, of the type commonly known as roofing shingles. More particularly, the present invention relates to high durometer roofing shingles of the type used to replace shingles made of slate, wood, asphalt or other hard, natural materials.
Specifically, the invention relates to a roofing shingle comprising at least percent, and preferably, 50 to 100 percent ethylene-propylene-diene terpolymer (EPDM) as the rubber component thereof and having a Shore "A" hardness of at (east 70 when tested (unaged) at room temperature (23°C). More preferably, the roofing shingles have a limiting oxygen index (LOI) of at least 30 when tested in accordance with ASTM D2863-91.
BACKGROUND OF THE INVENTION
High durometer roofing shingles used to cover sloped roofs are known in the art. Typically, these roofing shingles are used to replace shingles, shakes, or other covering elements made of slate, vvood, asphalt, or other hard or natural materials known in the art. These shingles are designed essentially to match the size, shape and texture of the shingle to be replaced, thereby maintaining essentially the same installation pattern or architectural perspective for the roof on which they are placed.
Heretofore, polymer blends of vulcanized scrap rubber or ground rubber and polyolefin resin have consistently been employed to produce these high durometer roof covering elements. For example, U.S. Patent Nos. 5,312,573 and 5,157,082 refer to processes for the production of useful articles made from reclaimed vulcanized rubber, preferably from tires, and polyolefin resins such as polyethylene or polypropylene. In each instance, the major component of the polymer blend is the inert vulcanized rubber.
More particularly, the inert vulcanized scrap rubber is often reclaimed from recycled tires, as noted hereinabove, or from off-specification rubber compounds available from tire manufacturing facilities or various other industrial facilities. Such rubber typically includes rubber materials such as natural rubber, 9707045(176) 2 synthetic polyisoprene, styrene butadiene rubber (SBR), polybutadiene, butyl rubber (IIR) or the like or mixtures and blends thereof. While such rubber may be particularly useful for the processes developed in the above-mentioned patents, these rubbers are not easily converted into new products and must oftentimes be employed with additional polymeric ingredients and/or compatibilizers in order to form the articles desired. For example, both patents noted hereinabove require the use of additional thermoplastic resins such as polyethylene and polypropylene, or copolymers thereof.
To the extent that EPDM may be included in the scrap or ground vulcanized rubber products of the prior art, EPDM has not been used in significant portions and is essentially inert in the scrap rubber compositions, acting, for the most part, as filler material since the rubber has already been cured. Nevertheless, single-ply EPDM-based roofing membrane or sheeting has rapidly gained acceptance as an effective covering and barrier to prevent the penetration of moisture through industrial and commercial flat roofs. Such EPDM membranes have outstanding weathering resistance and flexibility. These membranes are typically applied to the roof surface in a vulcanized or cured state, but is flexible enough to be transported in the form of a roll.
However, these membranes are not used on sloped roofs and do not possess the required hardness to be suitable for use on sloped roofs.
Traditional asphalt roofing shingles are well known, but typically do not weather well in cold temperatures. These traditional shingles are also somewhat susceptible to damage by hail. Furthermore, it is known that shingles of this type do not provide the heat aging, ozone, oxidation and moisture resistance of roofing membranes employing EPDM. Slate roofing shingles, while suitable for most purposes, are very heavy and very expensive in comparison to asphalt or polymeric roofing shingles. Thus, neither of these alternatives, i.e., asphalt or slate roofing shingles are particularly desirable.
Roofing shingles of the type described hereinabove are generally stiff, flat sheets moldable to essentially any size or shape. Where the roofing shingle to be developed will replace slate or asphalt shingles, it has been found that production of a rectangular roofing shingle which is about 0.25 inches thick, about 18 inches long and about 12 inches wide, is desirable. It will be 9707015(176) 3 appreciated, however, that other sizes and shapes may be more suitable and preferred when used to replace shingles of other types or when the slate or asphalt shingles being replaced are not of that same general size or shape, and the present invention should not be limited thereto.
Roofing shingles of the type described herein should preferably have a Shore "A" hardness (tested unaged at room temperature) of at least 70.
Shingles having lower durometer are not particularly suitable for use on sloped roofs where slate or asphalt shingles are being replaced. It is also believed desirable to provide roofing shingles which are more fire resistant than traditional asphalt shingles. Accordingly, these roofing shingles should preferably have an LOI of at least 30 percent when tested according to ASTM 2863-91. The oxygen index measurement is used as an indicator of flame retarding properties. It is believed that roofing shingles which do not have an LOI of at least 30 percent will not be sufficiently fire resistant so as to obtain a Class A fire rating for shingles accordingly to the UL 790 spread-of-flame test conducted by Underwriter Laboratories, Northbrook, ll.
SUMMARY OF INVENTION
It is, therefore, an object of the present invention to provide a high durometer roofing shingle capable of being used on sloped roofs.
It is another object of the present invention to provide a roofing shingle, as above, which comprises ethylene-propylene-diene terpolymer as the major polymeric component of the shingle.
It is still another object of the present invention to provide a roofing shingle, as above, which has superior weathering resistance and superior low temperature performance as compared to traditional asphalt roofing shingles.
It is yet another object of the present invention to provide a roofing shingle, as above, which provides superior heat resistance and ozone aging as compared to traditional asphalt roofing shingles.
It is still another object of the present invention to provide a roofing shingle, as above, which has better resistance to hail damage as compared to traditional asphalt shingles.

9707045(176) It is yet another object of the present invention to provide a roofing shingle, as above, which is sulfur curable.
It is still another object of the present invention to provide a roofing shingle, as above, which has increased fire resistivity as compared to traditional asphalt roofing shingles.
It is a further object to provide a method for covering a sloped roofing using the roofing shingles described herein.
At (east one or more of the foregoing objects, together with the advantages thereof over the known art relating to roof covering elements, and particular, roofing shingles, which shall become apparent from the specification which follows, are accomplished by the invention as hereinafter described and claimed.
In general, the present invention provides a roof covering element for use on sloped roofs, the covering element comprising 100 parts by weight of at least one ethylene-propylene-diene terpolymer, and from 0 to about 120 parts by weight of at least one impact modifying polymer, per 100 parts ethylene propylene-diene terpolymer, the covering element having a unaged Shore "A"
hardness at 23°C of at least 70. More preferably, the covering element has a limiting oxygen index of at least 30 when tested in accordance with ASTM
D2863-91.
Other aspects of the present invention are achieved by providing a roofing shingle comprising a polymeric component comprising from at least 45 to 100 percent by weight of at least one ethylene-propylene-diene terpolymer and from 0 up to 55 percent by weight of at least one impact modifying polymer, wherein the roofing shingles contains 100 parts by weight of the at least one ethylene-propylene-diene terpolymer; from about 50 to about 600 of at (east one filler selected from the group consisting of combustible and non-combustible fillers, per 100 parts by weight ethylene-propylene-diene terpolymer; and from about 30 to about 105 of at least one processing material per 100 parts by weight ethylene-propylene-diene terpolymer; wherein the roofing shingle has a Shore "A" hardness of at least 70, and more preferably, a limiting oxygen index of at least 30.

9707045(176) 5 The present invention also includes a method for covering a sloped roof, comprising the step of placing a plurality of roofing shingles on the roof in a preselected installation pattern, each roofing shingle including 100 parts by weight of at least one ethylene-propylene-diene terpolymer containing up to about 2 percent crystallinity and from 0 to about 120 parts by weight of at least one impact modifying polymer, and having a unaged Shore "A" hardness at 23°C
of at least 70. More preferably, the covering element has a limiting oxygen index of at (east 30 when tested in accordance with ASTM D2863-91, and further includes from about SO to about 600 of at least one filler selected from the group consisting of combustible and non-combustible fillers, per 100 parts by weight ethylene-propylene-diene terpolymer; and from about 30 to about 105 parts of at least one processing material per 100 parts by weight ethylene-propylene-diene terpolymer.
PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION
The present invention is directed toward the use of ethylene-propylene-diene terpolymers as the major polymeric component for high durometer roofing shingles suitable for use on sloped roofsyof new construction or for replacing other traditional roofing shingles typically used on sloped roofs. The invention seeks to take advantage of the outstanding weathering resistance and low temperature performance of the ethylene-propylene-diene terpolymers (EPDM), while maintaining the high durometer properties required of commercial roofing shingles of the type used on sloped roofs.
In the preferred embodiment, the high durometer roofing shingles of the present invention are designed to match closely the size, color, shape and texture of the slate or asphalt shingles. By closely matching the design of the original slate or asphalt shingles on older roofs, the installer can maintain essentially the same installation pattern or architectural perspective for the roof as was originally present.
The roofing shingles of the present invention are generally stiff, flat sheets moldable to essentially any size or shape suitable for use on the roof being replaced. In the present invention, the roofing shingles can be molded by essentially any process known in the art, but are preferably injection molded or 9707045(176) ~7 compression molded. These processes allow the finished product to have an appearance which is very similar to that of the original shingles of slate or asphalt.
Generally, roofing shingles of the present invention are preferably rectangular or of a shape substantially similar to that of the original shingle being replaced. For roofs originally having slate or asphalt shingles, it has been found that rectangular roofing shingles that are each about 0.25 inches thick, about inches long and about 12 inches wide, are most preferred. It will be appreciated, however, that other sizes and shapes may be more suitable and preferred when used to replace shingles of other types or when the slate or asphalt shingles being replaced are not of that same general size or shape, and the present invention should not be limited thereto. In any event, it will be appreciated that the size, color, shape and texture of the roofing shingle can be determined during the molding process. Thus, the roofing shingles of the present invention may take 1 S essentially any shape and have any desired color or texture and, therefore, need not meet any specific dimensional requirements. Again, they preferably are molded so as to appear very similar to the roofing shingles they are replacing.
The roof covering elements, i.e., shingles, of the present invention should also be easy to install. Preferably, the roofing shingles of the present invention should weigh approximately the same as the asphalt shingles they are replacing, and are generally lighter in weight than slate. Therefore, no additional reinforcing or supporting of the roof is necessary, and the shingles can essentially effect the same installation pattern as used to install the original roof covering elements.
Typically, high durometer roofing shingles are installed with roofing nails. Holes for these nails may be molded into each shingle, typically at the corners thereof. Alternatively, the roofing shingles may simply be susceptible to the penetration of the nail therethrough without cracking or shattering. Nail guns can be used to attach the roofing shingles to the roof with the nails.
The roofing shingles of the preferred embodiment are also typically marked such that, as they are being placed on the roof, the lower seven or eight inches remain exposed. Advantageously, the roofing shingles can also be cut with a utility knife so as to enable the installer to make any necessary changes to the size or shape 9707045(1761 7 of the shingles. In a preferred embodiment, tabs are molded on the sides of the shingle so as to align properly the shingles and to ensure consistent lateral spacing.
As noted hereinabove, the roofing shingle of the present invention contains at least 45 percent EPDM, preferably, about 50 to 100 percent EPDM, and more preferably, about 80 to 100 percent EPDM as the polymeric component of the composition. Where an additional polymeric component is used, the added component is preferably one or more polyolefin resins such as polyethylene or polypropylene, or a copolymer of ethylene and propylene (EPM).
Alternatively or in addition, other copolymers such as ethylene-butene copolymers or ethylene-octene copolymers may be employed. In any event, these polymers, i.e., those other than EPDM, act as impact modifiers and stiffen or otherwise increase the durometer of the composition, but are not added in an amount which will be more than 55 percent of the total virgin polymer content of the roofing shingle. For purposes of this disclosure, these polymers other than EPDM will be referred to as "impact modifying polymers." Moreover, there are no adhesive enhancing polymers or polymeric tackifiers added to the composition as are often found in EPDM-based roof sheeting membranes for flat roofs.
The term EPDM is used in the sense of its definition as found in ASTM
D-1418-94 and is intended to mean a terpolymer of ethylene, propylene and a diene monomer. Although not to be limited thereto, illustrative methods for preparing such terpolymers are found in U.S. Pat. No. 3,280,082 the disclosure of which is incorporated herein by reference. Other illustrative methods can be found, for example, in Rubber and Chemistry & Technology, Vol. 45, No. 1, Division of Rubber Chemistry (March 1992); Morton, Rubber Technology, 2d ed., Chapter 9, Van Nostrand Reinhold Company, New York (1973); Polymer Chemistry of Synfhefic Elastomers, Parf ll, High Polymer Series, Vol. 23, Chapter 7, John Wiley & Sons, Inc. New York (1969); Encyclopedia of Polymer Science and Technology, Vol. 6, pp. 367-68, Interface Publishers, a division of John Wiley & Sons, Inc., New York (1967); Encyclopedia of Polymer Science and Technology, Vol. 5, p. 494, Interface Publishers, a division of John Wiley & Sons, Inc., New York (1966); and Synfhetic Rubber Manual, 8th ed., International Institute of Synthetic Rubber Producers, Inc. (1980).

9707045(176) 8 The preferred EPDM terpolymers of the present invention are substantially amorphous. That is, at least one EPDM terpolymer employed to make the roofing shingle of the present invention should have less than about two percent crystallinity, and preferably, less than about 1.1 percent crystallinity.
More particularly, the EPDM roofing shingle composition of the present invention should have about 80 to 100 parts by weight of at least one EPDM terpolymer having up to about two percent crystallinity, and 0 to about 20 parts by weight of an EPDM terpolymer having more than about two percent crystallinity. More preferably, the composition should include at least 95 parts, and even more preferably 100 parts, by weight of amorphous EPDM having up to 2 percent crystallinity and, optionally, only up to about 5 parts by weight crystalline or a semi-crystalline EPDM having more than 2 percent crystallinity. Even more preferably, the composition includes about 95 to 100 parts by weight of an amorphous EPDM containing up to 1.1 percent crystallinity and 0 to about 5 parts by weight of an EPDM having more than 1.1 percent crystallinity.
Any EPDM containing up to about two percent, and more preferably, 1.1 percent, crystallinity from the ethylene component and exhibiting the properties discussed hereinbelow should be suitable for use in the present invention. Typically, amorphous EPDMs having less than about 65 weight percent ethylene and from about 1.5 to about 4 weight percent of the diene monomer with the balance of the terpolymer being propylene or some other similar olefin type polymer is desired. Such EPDMs also preferably exhibit a Mooney viscosity (MU1 + 4 at 125°C) of about 40 to 65 and more preferably, of about 45 to 55. Preferably, the EPDM does not have more than about 4 weight percent, and more preferably, not less than 2 weight percent, unsaturation.
The diene monomer utilized in forming the EPDM terpolymer is preferably a non-conjugated diene. Illustrative examples of non-conjugated dienes which may be employed are dicyclopentadiene, alkyldicyclopentadiene, 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,4-heptadiene, 2-methyl-1,5-hexadiene, cyclooctadiene, 1,4-octadiene, 1,7-octadiene, 5-ethylidene-2-norbornene, 5-n-propylidene-2-norbornene, 5-(2-methyl-2-butenyl)-2-norbornene and the like.

9707045(176) Typical EPDM terpolymers having less than 2 percent crystallinity are available from Exxon Chemical Co. under the tradename Vistalon°, from Uniroyal Chemical Co. under the tradename Royalene°, and from DSM Copolymer under the tradename Keltan°. For example, one preferred low Mooney, -amorphous EPDM terpolymer is available from Uniroyal Chemical Co. under the Royalene tradename and has a Mooney viscosity (MU4 at 125°C) of about 46 ~ S, an ethylene content of from about 69 to about 70 weight percent and between 2.4 and 3.2 weight percent unsaturation. Another suitable Royalene EPDM
terpolymer has a higher Mooney viscosity (MU4 at 125°C) of about 62 ~
5, an ethylene content of about 70 weight percent and about 2.7 weight percent unsaturation.
Another example of an EPDM having less than two weight percent crystallinity is available from DSM copolymer under the tradename Keltan. This amorphous EPDM terpolymer has a Mooney viscosity (MU4 at 125°C) of about 50 + 5, an ethylene content of about 70 weight percent, about 2.6 weight percent unsaturation and a specific gravity of about 0.87 at 23°C.
Still another example of an EPDM having less than 2 weight percent crystallinity is also available from Exxon Chemical Co. under the same tradename Vistalon. This amorphous EPDM terpolymer has a Mooney viscosity (ML/1 +4 at 125°C) of about 62 ~ 5, an ethylene content of about 69 weight percent and about 2.7 weight percent unsaturation.
It will be appreciated that the subject roofing shingles may comprise 100 parts by weight of an amphorous EPDM as the sole elastomeric polymer for the composition. However, it is contemplated that more than one EPDM having less than 2 weight percent crystallinity may be employed. For example, the shingles of the present invention may include a flame retardant package which includes an amorphous EPDM as the polymer binder as well as the amorphous EPDM component. As more specifically detailed hereinbelow, flame retardant packages commercially available from Anzon Chemical Company under the tradename Fyrebloc, include from about 10 to 20 percent by weight EPDM and, more preferably, from about 15 to about 17.5 percent by weight EPDM, as the polymeric binder for the total flame retardant package. Thus, the amount of EPDM employed includes the EPDM from the flame retardant package as well as 9707045(176) 10 that which is directly compounded as virgin EPDM terpolymer into the roofing shingle composition.
It will also be noted that certain fillers such as cryogenically ground EPDM rubber may include EPDM terpolymers. However, because these fillers are not virgin EPDM terpolymers, they have not been figured in the calculation of parts or percentages employed. It will be appreciated that, if all EPDM
terpolymer is taken into account, the subject roofing shingle composition will include more than 50 percent EPDM in the total polymer content.
When EPDM terpolymers having more than 2 percent crystallinity from the ethylene component are employed, these EPDMs preferably should contain at least about 65 weight percent ethylene and from about 2 to about 4 weight percent of the diene monomer with the balance of the terpolymer being propylene or some other similar olefin type polymer. Although not necessarily limiting, such EPDMs also should exhibit a Mooney viscosity (ML/4 at 125°C) of at least about 45 and no higher than about 60 and should have less than about 3.5 weight percent of unsaturation. However, 45 to 50 is preterred. Non-conjugated dienes like those exemplified above can also be used for these types of EPDMs as well. It will be appreciated, however, that the total EPDM
terpolymers utilized will be characterized as having 2 percent or less crystallinity.
As noted hereinabove, at least one impact modifying polymer selected from the group consisting of polyolefin resins or copolymers thereof may be blended with the EPDM to form the polymeric component of the EPDM-based shingle composition. By the term "impact modifying polymer" it is meant that these polymers provide the roofing shingle composition with more stiffness and may increase the impact strength of the composition. Essentially any polyolefin resin or copolymer thereof capable of imparting the characteristics described hereinabove may be suitable for the roofing shingle composition of the present invention. Preferably, 0 to about 20 percent by weight of the total roofing composition may be made from these impact modifying polymers.
More particularly, from 0 to about 120 parts, and more preferably, from 0 to about 50 parts by weight of these polymer resins or copolymers may be employed, per 100 parts EPDM. Most preferred, with respect to the polyolefin resins, are low density polyethylene (I.DPE), linear low density 9707045(176) 1 1 polyethylene (LLDPE), high density polyethylene (HDPE), and atactic and isostatic polypropylene. Suitable copolymers include, but are not necessarily limited to, ethylene-propylenecopolymers,ethylene-butenecopolymers,and ethylene-octene copolymers. Generally, the preferred polyoletm resins and copolymers thereot should provide high impact strength to the resultant roofing shingle composition.
One particularly useful polyolefin resin is LDPE 722 M, a low density polyethylene commercially available from Dow Plastics. LDPE 722 M has a melt flow index of 8 grams/10 minutes, peak melt temperature of 112°C as determined by DSC and a specific gravity of 0.9160 at 23°C.
Differential scanning calorimetry (DSC) is used to measure the emission or consumption of heat accompanying a physical change or a chemical reaction as a function of temperature or time in the range of -150°C to 725°C.
Also of particular use are certain LLDPEs, which may also be considered ethylene-octene copolymers, such as are available from Dow Plastics under the tradename Dowlex°. There are a variety of Dowlex ethylene-octene copolymers which generally differ in their peak melt temperatures and specific gravity. For example, Dowlex 2027 has a peak melt temperature of 113°C
as determined by DSC and a specific gravity of 0.941 glcc at room temperature whereas Dowlex 2038 and Dowlex 2045 have peak melt temperatures of 127°C
and 124°C, respectively, and specific gravities of 0.935 g/cc and 0.920 glcc, respectively.
A preferred HDPE resin is Nova 79 G produced by NOVA Chemical Ltd. This resin has a peak melt temperature of 132°C and a specific gravity of about 0.96 at 23°C. Another suitable HDPE is 62013 commercially available from Dow Plastics. HDPE 62013 has a peak melt temperature of 131 °C and a specific gravity of 0.945 at 23°C.
Other resins which may have utility in this invention include a number of HDPE resins produced by Dow Plastics. Some of the typical properties of these resins are shown in Table I hereinbelow.

9707045(176) 12 Comparison of Suitable High Density Polyethylene (HDPE) Resins Tradename Melt Index (MI) Specific gravity (gramsll0 minutes) (grams/cc) 04352N 4 0.952 06153C 6.3 0.953 08254N 7 0.954 10062N 10 0.962 12350N 12 0.960 17350N 17 0.950 25355N 25 0.955 30360M 30 0.960 40360M 38 0.958 Also preferred are ethylene-propylene copolymers (EPMs) such as those available from Exxon Chemical Company under the registered tradename Vistalon° and DSM Copolymer under the registered tradename Keltan°. The term EPM is used in the sense of its definition as found in ASTM D-1418-94 and is intended to mean a copolymer of ethylene and propylene. Some typical properties of ethylene-propylene copolymers include having an ethylene content of from about 45 percent to about 72 percent by weight, a Mooney viscosity (MU4 at 125°C) of from about 25 to 55, a glass transition temperature of from about -40°C to about -60°C. Ethylene-propylene copolymers are without any unsaturation, and these polymers have excellent long-term heat and ozone aging resistance as well as provide a smooth appearance to the molded shingle. A
typical EPM suitable for use in the present invention is available from DSM
Copolymer under the tradename Keltan° 740. This EPM has a Mooney viscosity (MU4 at 125°C) of about 63 and an ethylene content of about 60 weight percent.
Other EPMs are also suitable. For instance, Keltan° 3300A and have Mooney viscosities (MU4 at 125°C) of about 35 and about 40, respectively, while Vistalon° 808 and 878 have Mooney viscosities (ML/4 at 125°C) of about 46 and 53, respectively. These ethylene-propylene copolymers are available in dense or friable bales.

9707045(176) 1 3 Yet another suitable copolymer of propylene and ethylene is Pro-Fax SR-549M produced by Montell. This resin has a peak melt temperature of 162°C, a 11-15 melt index range, an izod range at 23°C from about 1.5 to 2, and a specific gravity of about 0.95 at 23°C.
Other suitable copolymers include those saturated ethylene-octene copolymers which provide excellent weatherability and are available from Dow Plastics under the tradename Engage. For example, Engage° 8100 and Engage 8200 have octene contents of about 24 and 25 weight percent, respectively.
These general purpose elastomers have Mooney viscosities (MU4 at 121 °C) 70 ranging from about 23 to 35 and specific gravities of about 0.87 at 23°C.
Where these polyolefin resins and copolymers thereof are blended with the EPDM of the shingle composition, the polymer blend to be employed in the shingle composition generally includes major amounts of EPDM and only minor amounts of the impact modifying polymer(s). In fact, the polymer blend typically includes at least 100 parts by weight EPDM and up to about 120 parts by weight of an impact modifying polymer, based upon the weight of the EPDM. While more than one impact modifying polymer may be used, the total amount of all these types of polymers combined should not exceed the amount of EPDM
(including cryogenically ground EPDM rubber and virgin EPDM for flame retardants and the like) provided.
In addition to the EPDM terpolymers and the impact modifying polymers such as the polyolefin resins and copolymers thereof, as discussed hereinabove, the roofing shingle composition of the present invention may also include fillers, processing aids and curatives as well as other optional components including activators and flame retardant packages, all of which are discussed hereinbelow. The amounts of fillers, processing materials, curing agents, and other additives used in the roofing shingle composition will be expressed hereinafter as parts by weight per 100 parts by weight EPDM terpolymer, since EPDM is the base component of the composition. Accordingly, where the term "phr" is used, it will be understood to mean parts by weight per 100 parts by weight EPDM terpolymer, even if an additional impact modifying polymer is employed.

9707045(176) 14 With respect to the fillers, suitable fillers are selected from the group consisting of combustible and non-combustible materials, and mixtures thereof.
Examples of combustible materials include organic materials such as carbon black and ground coal. Examples of non-combustible materials include both organic and inorganic materials such as cryogenically or ambiently ground EPDM rubber, clay, mineral fillers, and the like. Generally, these materials can be added to the formulation in amounts ranging from 50 to 600 parts by weight, per 100 parts EPDM terpolymer.
Organic combustible materials like carbon black may be used in amounts ranging from about 5 parts to about 185 parts per 100 parts of EPDM
terpolymer (phr), depending largely upon whether the resultant shingle composition is to be fire resistant. Where the shingle will be fire resistant, carbon black and other combustible materials should be limited and, preferably, may be used in amounts ranging from about 5 to about 70 phr. If fire resistance is not a concern, much higher loadings of carbon black may be used, preferably in the range of about 50 to about 200 phr. The carbon black useful herein may be any carbon black suitable for the purposes disclosed hereinbelow. Preferred are furnace blacks such as GPF (general purpose furnace), FEF (fast extrusion furnace) and SRF (semi-reinforcing furnace). Most preferred in N650 HiStr GPF
black, a petroleum-derived, black reinforcing filler having an average particle size of about 60 nm and a specific gravity of about 1.80 glcc.
Other combustible materials such as ground coal may also be employed as part of the filler in the roofing shingle compositions of the present invention. Ground coal is a dry, finely divided black powder derived from a low volatile bituminous coal. The ground coal typically has a particle size ranging from a minimum of 0.26 microns to a maximum of 2.55 microns with the average particle size of 0.69 ~ 0.46 as determined on 50 particles using Transmission Electron Microscopy. The ground coal produces an aqueous slurry having a pH
of about 7.0 when tested in accordance with ASTM D-151 Z. A preferred ground coal of this type is designated Austin Black which has a specific gravity of about 1.255 ~ 0.03, an ash content of about 4.58% and a sulfur content of about 0.65%. Austin Black is commercially available from Coal Fillers, Inc. of Bluefield, 9707045(176) ~ 5 Virginia. Amounts range from about 5 to about 65 phr with about 15 to about 35 phr being preferred, if used.
With respect to non-combustible materials, there are many types of materials which can be used as non-combustible fillers for the roofing shingle composition of the present invention. One particularly useful and preferred non-combustible material is cryogenically ground rubber. Essentially any cryogenically or ambiently ground rubber may be employed as a filler in the roofing shingle composition. Preferred cryogenically or ambiently ground rubbers are cryogenically or ambiently ground EPDM rubber. The preferred ground EPDM rubber is a fine black rubbery powder having a specific gravity of about 1.16 ~ 0.015g/cc and a particle size ranging from about 30 to about 300 microns with an average particle size ranging from about 40 to about 80 microns.
When carbon black is included in the roofing shingle composition, the amount of ground EPDM rubber may range from about 25 to about 100 parts per 100 parts of the EPDM terpolymer. In the absence of any carbon black, the amount of cryogenically or ambiently ground rubber may be significantly higher, from about 50 to about 600 parts by weight per 100 parts EPDM terpolymer (phr). It has been found that these ground rubbers provide significant reductions to the cost of the composition while maintaining the desired properties of the composition, since the ground rubber is essentially inert.
Also particularly useful and preferred with respect to non-combustible materials are non-black mineral fillers. These mineral fillers are essentially inorganic materials which generally aid in reinforcement, heat aging resistance, green strength performance, and flame resistance. There are a number of different inorganic materials that fall into this category of fillers. For example, these mineral fillers include a number of different types of clays, including hard clays, soft clays, chemically modified clays, water-washed clays, and calcined clays. Other examples of mineral fillers suitable for use in the present invention include mica, talc, alumina trihydrate, antimony trioxide, calcium carbonate, titanium dioxide, silica, and certain mixtures thereof. Still other inorganics such as magnesium hydroxide and calcium borate ore may also be employed. In some instances, these fillers may completely or partially replace "black" fillers, i.e.
carbon black and other petroleum-derived materials. Generally, however, one 9707045(176) 1 6 or more of these mineral fillers are employed in amounts ranging from about 25 parts to about 250 parts by weight, per 100 parts EPDM terpolymer.
Any of four basic types of clays are normally used as fillers for rubber elastomers. The different types of clay fillers include airfloated, water washed, calcined and surface treated or chemically modified clays.
The airfloated clays are the (east expensive and most widely used.
They are divided into two general groups, hard and soft, and offer a wide range of reinforcement and loading possibilities. Hard Clays may be used in the amount of about 20 parts to about 300 parts per 100 parts EPDM (phr), preferably in an amount from about 65 to 210 phr. Preferred airfloated hard clays are commercially available from J.M. Huber Corporation under the tradenames Barden R°; and LGB° from Kentucky-Tennessee Clay Company, Koalin Division, Sandersville, GA, under the tradename Suprex°
The airfloated soft clays may be used in amounts ranging from about 20 parts to about 300 parts per 100 parts of EPDM (phr), preferably in an amount from about 75 to 235 phr. The preferred airfloated soft clays are available from J.M. Huber Corporation under the tradename K-78°, from Evans Clay Company under the tradename Hi-White R° and from Kentucky-Tennessee Clay Company, Koalin Division, Sandersville, GA, under the tradename Paragon "'.
Particularly preferred is Hi-White R°, an air-floated soft clay characterized as having a pH of about 6.25 ~ 1.25, an oil absorption of 33 grams/100 grams of clay, a particle size of 68% ~ 3, and a specific gravity of about 2.58. This clay is also finer than two microns.
Water washed clays are normally considered as semi-reinforcing fillers.
This particular class of clays is more closely controlled for particle size by the water-fractionation process. This process permits the production of clays within controlled particle size ranges. The preferred amounts of water washed clays are very similar to the preferred amounts of airfloated soft clays mentioned hereinabove. Some of the preferred water washed clays include Polyfil°
DL, Polyfil° F, Polyfil° FB, Polyfil° HG-90, Polyfil° K and Polyfil° XB; all commercially available from J.M. Huber Corporation.
The third type of clay includes the calcined clay. Clays normally contain approximately 14 percent water of hydration, and most of this can be 9707045(176) 1 7 removed by calcination. The amount of bound water removed determines the degree of calcination. The preferred ranges of calcined clays are very similar to the preferred amounts of airfloated hard clays mentioned hereinabove. Some of the preferred calcined clays include Polyfil° 40, Polyfil° 70, and Polyfil° 80, all commercially available from ).M Huber Corporation.
The last type of clay includes chemically modified reinforcing clays.
Cross-linking ability is imparted to the clay by modifying the surface of the individual particles with a polyfunctional silane coupling agent. Chemically modified clays are used in the amount of from about 20 parts to about 300 parts per 100 parts EPDM (phr), preferably in an amount from about 60 to 175 phr.
Normally, the specific gravity of most of these clays is about 2.60 at 25 ° C. The preferred chemically modified clays are commercially available from J.M. Huber Corporation and include those available under the tradenames Nucap°, Nulok°
and Polyfil°. Other preferred chemically modified clays are commercially available from Kentucky-Tennessee Clay Company under the tradenames Mercap "' 100 and Mercap° 200.
As an alternative to the clays, a silicate may have utility in the present invention. For example, synthetic amorphous calcium silicates such as those which are commercially available from the ).M. Huber Company under the tradename Hubersorb° may be utilized. One particular silicate, Hubersorb° 600, is characterized as having an average particle size of 3.2 micrometers (by the Coulter Counter Method), oil absorption of 450 ml/100 grams of calcium silicate, a BET (Brunaver-Emmet-Teller nitrogen adsorption procedure) surface area of m2/gram and a pH (5% solution) of 10.
Other silicates which may be used in the composition of the present invention include precipitated, amorphous sodium aluminosilicates available from the J.M. Huber Company under the tradename Zeolex°. Zeolex 23 has a BET
surface area of about 75 m2/gram, a refractive index at 20°C of about 1.51, and a pH of about 10.2 determined by slurring 20 grams of silicate with 80 grams of deionized water. In comparison, Zeolex 80 has a BET surface area of about 115 m2/gram, a refractive index at 20°C of about 1.55, and a pH of about 7.
The average particle size, density, physical form and oil absorption properties are similar to each other.

9707045(176) 1$
Reinforcing silicas may also be used as non-black fillers, preferably in conjunction with one or more of the chemically modified clays noted hereinabove. Silica (silicon dioxide) utilizes the element silicon and combines it in a very stable way with two oxygen atoms. Generally, silicas are classed as wet-processed, hydrated silicas because they are produced by a chemical reaction in water, from which they are precipitated as ultrafine, spherical particles.
However, there are in reality two different forms of silica, crystalline and amorphous (noncrystalline). The basic crystalline form of silica is quartz, although there are two other crystalline forms of silica that are less common -tridymite and cristobalite. On the other hand, the silicon and oxygen atoms can be arranged in an irregular form as can be identified by X-ray diffraction.
This form of silica is classified as amorphous (noncrystalline), because there is no detectable crystalline silica as determined by X-ray diffraction. The most preferred forms of silica, i.e., a fine particle, hydrated amorphous silica, are available from PPG Industries, Inc. and J.M. Huber Corporation in a low dust granular form. These silicas typically are available from PPG Industries under the tradenames HiSil° and Silene~. Reinforcing silicas are generally characterized in terms of surface area (m2lgram by the BET procedure) or particle size as determined by either electron microscopy or the Coulter Counter Method.
These silicas can be employed in the amount of about 10 parts to about 110 parts per 100 parts EPDM terpolymer (phr), preferably in an amount from about 10 to 30 phr. The useful upper range is limited by the high viscosity imparted by fillers of this type.
Stil! other fillers include calcium carbonate, titanium dioxide, talc (magnesium silicate), mica (mixtures of sodium and potassium aluminum silicate), alumina trihydrate, antimony trioxide, magnesium hydroxide, and calcium borate ore. The amount of these fillers may vary significantly depending upon the number and amount of other particular fillers employed, but typically are employed in amounts ranging from about 25 to about 250 parts by weight, per 100 parts EPDM terpolymer. The most preferred of these mineral fillers include 100 percent magnesium hydroxide (200 parts or less), or mixtures of magnesium hydroxide (less than 100 parts) in combination with alumina trihydrate (less than 9707045(176) 19 100 parts) and mistron vapor talc (less than 50 parts). Parts per 100 parts EPDM
terpolymer are by weight, unless otherwise indicated.
One particularly useful form of talc is Mistron Vapor Talc (MVT) commercially available from Luzenac America, Inc. Mistron Vapor Talc (MVT) is a soft, ultra-fine, white platy powder having a specific gravity of 2.75.
Chemically, Mistron Vapor Talc is ground magnesium silicate having a median particle size of 1.7 microns, an average surface area of 18 m2lgram and a bulk density (tapped) of 201bs/ft3.
Alumina trihydrate is a finely divided, odorless, crystalline, white powder having the chemical formula AI203~3H20. Alumina trihydrate is utilized in the present invention to enhance the green strength of the EPDM terpolymer or the other polyolefins. Preferably, alumina trihydrate has an average particle size ranging from about 0.1 micron to about 5 microns, and more preferably, from about 0.5 microns to about 2.5 microns.
A preferred ground alumina trihydrate for use with the invention is designated H-15 (or ATH-15), and has a specific gravity of about 2.42, and an ash content of about 64-65 weight percent. ATH-15 is commercially available from Franklin Industrial Minerals, of Dalton,.~Georgia. Other alumina trihydrates produced by Franklin Industrial Minerals which are believed to have utility in this invention include those designated H-100, H-105, H-109, and H-990. Alumina trihydrate can also be advantageously used as a flame retardant and smoke suppressant in the EPDM-based roofing shingle composition of the present invention.
Other sources of alumina trihydrate are Micral 1000 and Micral 1500, available from J. M. Huber Corporation of Norcross, Georgia, which have a median particle size of about 1.1 microns and about 1.5 microns, respectively.
Both alumina trihydrates have a specific gravity of about 2.42, an ash content of about 64-65 weight percent and a loss on ignition (LOI) at 1000°F of about 34.65 percent by weight. Other alumina trihydrates produced by this corporation which are believed to have utility in this invention include those designated as Micral 932 and Micral 532 as well as superfine alumina trihydrates including SB-632 and SB-805.

9~o~oasmbt 20 Another particularly useful mineral filler is the ore of calcium borate.
This filler is available in various particle size grades from American Borate Company, Virginia Beach, Virginia, under the tradename Colemanite~ and has the chemical formula Ca2B6011~5H20. Colemanite has a specific gravity of about 2.4. This ore has an average particle size of about 0.1 to about 5 microns, and more preferably, from about 0.5 microns to about 2.5 microns.
Still another mineral filler which may be particularly suit~ible for use in the roofing shingle composition of the present invention is magnesium hydroxide. Magnesium hydroxide (Mg(OH)2) is a finely divided, white powder which is an extremely effective smoke suppressant as well as a flame retardant additive. It is well documented that Mg(OH)2 is highly effective in reducing smoke. Thus, this mineral filler is believed to be particularly useful where smoke and fire resistivity is a concern. To that end, this mineral filler oftentimes will replace other mineral fillers such as silica or any of the clays in the composition.
Commercial grades of magnesium hydroxide are available from Martin Marietta Magnesia Specialties, Inc. under the tradename MagShield. MagShield S is a standard size magnesium hydroxide with a mean particle size of about 6.9 microns. MagShield M has a mean size of about 1.9 microns. Both of these grades of magnesium hydroxide are about 98.5 percent pure, have about 0.3 percent loss on drying and about 30.9 percent by weight loss on ignition, and a specific gravity of about 2.38 at 23°C.
Clay, titanium dioxide, alumina trihydrate, magnesium hydroxide, talc and mica can also be used to develop a gray colored roofing shingle. The desirable gray color may be obtained through the use of different combinations of the non-black mineral fillers. It will be appreciated that in order to provide the gray color, it is also necessary to reduce substantially the amount of carbon black in the formulation.
The roofing shingle composition of the present invention may also contain one or more processing materials. Processing materials are generally included to improve the processing behavior of the composition (i.e. to reduce mixing time and to increase the rate of sheet forming) and includes processing oils, waxes and other similar additives. A process oil may be included in an amount ranging from about 30 parts to about 105 parts process oil per 100 parts 9707045(176) 21 EPDM terpolymer (phr), preferably in an amount ranging from about 60 phr to about 85 phr. A preferred processing oil is a paraffinic oil, e.g. Sunpar 2280, which is available from the Sun Oil Company. Other petroleum derived oils including naphthenic oils are also useful. Liquid halogenated paraffins may serve as softeners or extenders and are also often desirable as flame retardant additives.
A preferred liquid chlorinated paraffin is Doverguard 5761, which features about 59 weight percent chlorine and can be used both as a softener as well as a fire retardant additive. This liquid paraffin has a viscosity of about 20 poise at 25°C and a specific gravity of about 1.335 at 23°C.
Another liquid paraffin having utility in this invention is a liquid bromochlorinated paraffin flame retardant additive, i.e., Doverguard 8207A having 30 and 29 weight percent bromine and chlorine, respectively. Doverguard 8207A has a specific gravity of about 1.42 at 50°C. Both liquid halogenated paraffins are commercially available from Dover Chemical Corporation, a subsidiary of ICC
Industries, Inc.
A homogenizing agent may also be added, generally in an amount of less than 10 parts by weight, and preferably, in an amount of about 2 to 5 parts by weight per 100 parts EPDM terpolymer. One particularly suitable homogenizing agent is available in flake and pastille form from Struktol Company under the tradename Struktol 40 MS. The preferred homogenizing agent is composed of a mixture of dark brown aromatic hydrocarbon resins having a specific gravity of about 1.06 g/cc at 23°C.
Yet another type of useful processing aid are the phenolic resins.
Phenolic resins are known to provide tack and green strength as well as long term aging properties to the composition. When used, such fillers are typically employed in minor amounts of less than 10 parts by weight, more preferably about 2 to 3 parts by weight, per 100 parts EPDM terpolymer.
In addition to the above ingredients which are mixed to form a masterbatch in the preferred embodiment, activators such as zinc oxide and stearic acid may optionally be added to and made a part of the masterbatch.
Amounts of these activators can vary depending upon processing needs, but it is conventional to add about 5 phr zinc oxide and about 1 phr stearic acid to the 9707045(176) 22 masterbatch. These activators are particularly useful with sulfur cure packages as explained hereinbelow.
A fire retardant package may also be added to the composition where increased fire resistance is desired. There are a variety of fire retardant packages commercially available for use with rubber compositions. Generally, the flame retardant system incorporated in the roof shingle composition can be made of different types of materials including ratios of decabromodiphenyl oxide (DBDPO) or related bromine containing additives and antimony trioxide. Various inorganic materials, clay, alumina trihydrate, magnesium hydroxide, silica, mica, talc and zinc carbonate can be used as part of the filler system as well as flame retardant additives. Certain halogenated paraffins can be used as the softener or extender and still impart flame resistance to the roof shingle composition.
One particularly useful fire retardant package is available from Anzon Chemical Company. This package is 85 percent active and contains 15 percent by weight EPDM terpolymer as a binder for the package. The package also includes a mixture of antimony trioxide and decabromodiphenyl oxide. Another useful fire retardant package is also available from Anzon Chemical Company of Philadelphia, Pennsylvania, and is 82.5 percent active. The fire retardant package contains 17.5 percent by weight EPDM as the binder. Zinc borate, decabromodiphenyl oxide and antimony trioxide are further included in the package. It will be appreciated that, where used, these packages are employed in amounts ranging from about 50 to 70 parts by weight, per 100 parts EPDM.
As discussed hereinabove, it will also be appreciated that these fire retardant package may contain a portion of the EPDM terpolymer employed in the composition.
The roofing shingle composition may also include a cure package containing a curing agent and at least one organic accelerator in order to effect full crosslinking or curing of the composition prior to its use on a roof. The composition is typically vulcanized for a period of time at an elevated temperature to insure crosslinking. The polymeric composition may be cured using any of several well-known curing agents, but preferably the cure p~~ck~ige of the present invention includes sulfur and one or more sulfur vulcanizing accelerators.

9707045(176) 23 Generally, the sulfurlaccelerator cure package employed in the roofing shingle composition of the present invention is provided in amounts ranging from about 1.5 to about 10 phr, depending upon the amount of sulfur utilized.
As noted, the sulfur and sulfur-containing cure systems used in the present invention typically include one or more sulfur vulcanizing accelerators.
Suitable accelerators commonly employed include, for example, thioureas such as ethylene thiourea, N,N-dibutylthiourea, N,N-diethylthiourea and the like;
thiuram monosulfides and disulfides such as tetramethylthiuram monosulfide (TMTMS), tetrabutylthiuram disulfide (TBTDS), tetramethylthiuram disulfide (TMTDS), tetraethylthiuram monosulfide (TETMS), dipentamethylenethiuram hexasulfide (DPTH) and the like; benzothiazole sulfenamides such as N-oxydiethylene-2-benzothiazole sulfenamide, N-cyclohexyl-2-benzothiazole sulfenamide, N,N-diisopropyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide (TBBS) and the like; other thiazole accelerators such as Captax (MBT) or Altax (MBTS), 2-mercaptoimidazoline, N,N-diphenylguanadine, N,N-di-(2-methylphenyl~guanadine, 2-mercaptobenzothiazole, 2-(morpholinodithio)benzothiazole disulfide, zinc 2-mercaptobenzothiazole and the like; dithiocarbamates such as tellurium diethyldithiocarbamate, copper dimethyldithiocarbamate, bismuth dimethyldithiocarbamate, cadmium diethyldithiocarbamate, lead dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dimethyldithiocarbamate and zinc dibutyldithiocarbamate (ZDBDC).
It should be appreciated that the foregoing list is not exclusive, and that other vulcanizing agents known in the art to be effective in the curing of EPDM terpolymers employed in the polymer blend may also be utilized. For a list of additional vulcanizing agents, see The Vanderbilt Rubber Handbook, RT
Vanderbilt Co., Norwalk CT 06855 (1990). It should also be understood that these sulfur donor-type accelerators may be used in place of the elemental sulfur or in conjunction therewith. Suitable amounts of sulfur to be used in the cure package can be readily determined by those skilled in the art, and generally range from about 0.25 to 2.0 phr, while the amount of accelerator can also be readily determined by those skilled in the art and generally range from about 1.5 to about 10 phr, depending upon the amount of sulfur, the vulcanizing accelerators 9707045016) 24 selected and the ultimate destination or use of the EPDM-based roofing shingle composition.
It will be appreciated that the sulfur and the sulfur accelerators may be added in amounts suitable for curing the roofing shingle compositions on the rooftop. Thus, when employed as a rooftop curable roofing shingle in a warm climate, different accelerators and/or amounts thereof, known to those skilled in the art, can be selected as compared to those accelerators to be used for rooftop curing in cooler climates.
In order to be rooftop curable, the roofing shingle composition is not fully cured prior to application and need not be cured subsequent thereto. The presence of the cure package allows the roofing shingle composition to cure at temperatures of at least about 50°C, readily obtainable when exposed to sunlight in most climates.
Accelerators generally require a metal oxide, i.e., zinc oxide for cure activation in most all types of rubbers. Zinc oxide is almost always the metal oxide of choice because of its effectiveness and lack of toxicity. The amount of zinc oxide may vary, but about 1 to about 10 parts in the formulation have been found to give the desired effect. Also,; in order to initiate the vulcanization process, a small amount (generally about 1 to 2 parts by weight) of stearic acid is present in the shingle composition. Using heat, both zinc oxide and stearic acid act as cure activators in the presence of sulfur, one or more accelerators and unsaturated rubber to help promote the formation of sulfur crosslinks during the vulcanization process. Some of the initial chemical reactions which take place during the early stages of the vulcanization process include reacting zinc oxide with stearic acid to form salts of even greater vulcanization activity.
Zinc oxide itself acts as a cure activator or vulcanization promoter, speeding the rate of reaction of elemental sulfur with the unsaturation in the diene portion of the terpolymer. In addition to its use as a curing component, the sulfur component of the present invention may also be used in conjunction with zinc oxide to improve the heat aging resistance of the composition.
During the molding process, vulcanization temperatures as high as 210°C are generally adequate to complete vulcanization in about 1 to 7 minutes.

9707045(176) 25 The vulcanization time can be further reduced by elevating the molding temperature during the vulcanization process.
Other ingredients may also be included in the shingle composition. For example, additional conventional rubber compounding additives such as antioxidants, antiozonants and the like may be included in conventional amounts typically ranging from about 0.25 to about 4 phr.
The compounding ingredients can be preferably admixed or compounded in a Brabender° mixer or a type B internal mixer (such as a Banbury mixer), or any other mixer suitable for preparing viscous relatively uniform admixtures. When utilizing a type B Banbury internal mixer or a Brabender mixer, in a preferred mode, the dry or powdery materials (e.g., carbon black, mineral filler, zinc oxide, stearic acid, fire retardant additives, etc.) are added into the mixing cavity first followed by any liquid process oil or softeners (e.g., process oil, plasticizers, etc.) and finally, the polymeric components (e.g., EPDM, EPM, LDPE, HDPE, etc.) This type of mixing can be referred to as an upside-down mixing technique. The mixing time may vary from about 2.5 minutes to 5-6 minutes, depending on the melt characteristics of the polyethylene and polypropylene containing resins. The drop~or dump temperature of the first-stage mix (masterbatch) is usually about 163°C to 185°C. The masterbatch is refined and resheeted on a hot two-roll mix. The temperature of the mill rolls usually ranges from about 116°C to about 160°C.
Within a matter of minutes, the resheeted slab stock is cut to the desired dimensions and added strip by strip to the cavity of the mixing chamber.
After about 50 percent of the rubbery masterbatch has been added to the mixer, the cure package is discharged into the mixing chamber followed by the addition of the remainder of the masterbatch. The temperature of the rubbery mix is allowed to reach temperatures as high at about 300°F (150°C) for only a very short period of time (approximately 2 minutes or less). The second stage mix (final) is quickly resheeted to the desired dimensions again using a hot two-roll mix. The total mixing time involving the second stage mix (final) is usually no more than about two minutes. The freshly prepared fully compounded test specimens are press cured about 40 minutes at 320°F (160°C).
Typical test properties performed include those tests which indicate stress-strain properties, 9707045(176) 26 tear resistance, ozone aging resistance, weathering resistance, hardness, water absorption, heat aging resistance and oxygen index measurements.
In order to demonstrate the practice of the present invention, several roofing shingle compositions prepared according to the concepts of the present invention were compounded in a Brabender~ mixer using the above-described two-stage mixing technique. The dry or powdery materials (e.g., carbon black, mineral filler, zinc oxide, stearic acid, fire retardant additives, etc.) were charged into the mixing cavity first. Next, any process oil or softeners, e.g., process oil, plasticizers, etc., were added. Lastly, the elastomeric components, e.g., EPDM, EPM, LDPE, LLDPE, HDPE, etc.) were added to the cavity of the mixer.
The following examples are submitted for further illustrating the nature of the present invention and are not to be considered as a limitation of the scope thereof. Parts and percentages are by weight, unless otherwise indicated. The composition of each of the roofing shingle formulations prepared are shown in Table II hereinbelow.

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9707045(1761 29 a. Royalene High Mooney, Amorphous EPDM
b. Royalene Low Mooney,. Amorphous EPDM
c. N-650 HiStr GPF Black d. N-330 HAF Black e. Sunpar 2280 Process Oil f. Struktol 40 MS
g. Sovereign Chemical Co. Phenolic resin h. Air-Floated, Soft Clay (HiWhite R) i. Mistron Vapor Talc (MVT) j. FR Package (1 DB-385RC) k. FR Package (1 DB-58283) (. Dowlex 2045 m. Engage EG 8100 n. Chlorinated Paraffinic Oil 5761 (59 weight percent chlorine) 0. Micra11000 p. MagShield S
q. Nova 79G Resin r. Cryogenically ground EPDM rubber (80 Mesh) The examples illustrated in Table II comprise EPDM-based roofing shingle compositions. 'Examples 1-2 comprise 100 parts by weight of a 62 Mooney, amorphous EPDM terpolymer, about 155 parts N-650 HiStr GPF carbon black, about 10 parts N-330 HAF carbon, black (Example 1), about 15 parts coal filler (Example 2), about 85 parts paraffinic process oil, a processing aid, phenolic resin, zinc oxide and stearic acid. These ingredients are mixed to form a rubber masterbatch. About 3.9 parts of a mixture of sulfur and sulfur vulcanizing accelerators are then added to form the roofing shingle composition.
Examples 3-4 include a high Mooney, amorphous EPDM terpolymer, about 50 parts N-650 HiStr GPF black, about 16 parts coal filler, about 49 parts paraffinic process oil, about 65 parts of a fire retardant package, identified as Fyrebloc 1DB-38583 and 122 parts of a mixture of clay and talc. The types of curatives used in Examples 3-4 were identical to those used in Examples 1-2.
Examples 4-8 comprise a low mooney EPDM terpolymer, from about 50 to 120 parts of a mixture of N-330 and N-650 carbon black, from about 16 to 2U parts coal filler, from about 45 to 100 parts paraffinic process oil as well as clay, talc, a fire retardant package and the same sulfur vulcanizing accelerators as used in Examples 1-4.

9707015(176) 30 Examples 9-16 include 100 parts of a low Mooney, amorphous EPDM, from about 15 to 35 parts N-650 HiStr GPF black, about 17.5 parts coal filler (Example 16 only), from about 37 to 49 parts paraffinic process oil, about 15 parts chlorinated paraffin oil, from about 160 to 170 parts of a mixture of alumina trihydrate and magnesium hydroxide, from about 65 to 100 parts of either a LLDPE or HDPE resin and 55 to 100 parts of a cryogenically ground EPDM rubber (80 mesh) and the same sulfur vulcanizing accelerators as used in Examples 1-8.
The ingredients were mixed for about 2.5 minutes to about 6 minutes, depending on the specific melt characteristics of the polyethylene- and polypropylene-containing resins employed. The drop or dump temperature of the first-stage mix (masterbatch) was between about 163°C and 185°C.
The masterbatch was worked or refined, and resheeted on a hot two-roll mix. The temperature of the mill rolls was between about 116°C to 160°C.
Within a matter of minutes, the resheeted slab stock was cut to the desired dimensions and added strip by strip to the cavity of the mixing chamber. After about 50 percent of the rubbery masterbatch had been added to the mixer, a sulfur cure package was discharged into the mixing chamber followed by the addition of the remainder of first stage mix or masterbatch. The temperature of the rubbery mix was allowed to reach temperatures as high at about 150°C for only a very short period of time (about 2 minutes or less). The second stage mix was quickly resheeted to the desired dimensions again using a hot two-roll mix. The total mixing time involving the second stage mix for each composition was less than about two minutes. The freshly prepared fully compounded test specimens were then press cured 30 minutes at 160°C. Various tests were then performed on each specimen. The results of these tests are shown in Table III hereinbelow.
Specifically, the cure characteristics, viscosity and scorch measurements, stress-strain data, die C tear properties, cured compound hardness of the cured roofing shingle compositions were determined for each example of the present invention. The cure characteristics (cure rate, cure state, etc.) of the fully compounded roofing shingle compositions were determined using a Monsanto Oscillating Disc Rheometer in accordance with ASTM D 2084. The die oscillated at a three degree arc at 160°C during actual testing.

9707045(176) 31 The processing characteristics of the roofing shingle compositions were determined using a Monsanto Mooney Viscometer (MV-2000E) Tester. The specific test conditions involved using a large rotor (1.5 -inches in diameter) die attachment operating at 135°C during actual testing. The Mooney viscometer provided useful information involving the viscosity in the uncured, compounded state and processing (scorch) safety of the fully compound roofing shingle compositions. This test method (ASTM D 1696-89) can be used to determine incipient cure time and to determine the curing characteristics of vulcanizable compounds.
In testing, each of the roofing shingle compositions (Examples 1-16) were compression molded to a thickness of about 45 mils and cut into a plurality of dumbbell-shaped test specimens according to ASTM D 412 (Method A-dumbbell and straight specimens). Each test specimen was tested using a crosshead speed of 20 inches per minute on a table model 4301 Instron Universal Tester. The initial jaw separation was two inches. The Universal Tester (a testing machine of the constant rate-of-jaw separation type) is equipped with suitable grips capable of clamping the test specimens, without slippage.
Modulus, tensile strength and elongation at break measurements were obtained, and the test results were calculated in accordance with ASTM D 412.
All dumbbell-shaped test specimens were allowed to set at room temperature for about 24 hours before testing was carried out at 23°C using the appropriate metal die (90° angle die C). Die C tear specimens were also cut and tested under the came conditions as the dumbbell-shaped specimens. Again, the test specimens were allowed to set for about 24 hours before testing was carried out at 23 ° C.
Shore "A" hardness, which measures the hardness of the cured rubber vulcanizate, was measured with an indentor. Cured compound hardness measurements are based upon initial (instantaneous) indentation or indentation after a specified period of time (dwell time) or both. Each cured rubber vulcanizate is allowed to set for about 24 hours prior to testing. Increasing the level of impact modifying polymer increased the hardness of the roofing shingle composition.

9707045(176) 32 The Limiting Oxygen Index (LOI) was determined for a number of the roofing shingle compositions. LOI is defined as meaning the minimum concentration of oxygen, expressed as volume percent, in a mixture of oxygen and nitrogen that will support flaming combustion of a material initially at room temperature under the test conditions set forth in ASTM D 2863-91. Suitable testing equipment for determining the LOI of plastic and rubbery materials is the Stanton-Redcroft FTA flammability test unit. Custom Scientific Instruments (CSI), Inc., a subsidiary of Atlas Electric Devices Company, also commercially produces such flammability testing units.

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9707045(176) 35 As shown in Table III hereinabove, physical properties of each of the rubber compounds were measured and have been reported. The resultant EPDM
based roofing shingle compositions in Examples 1-8 (Table II) can be characterized as having tensile at break measurements in excess of 1275 psi and die C tear values ranging between 195 and 265 Ibs./inch at 23°C. The elongation at break values easily exceed the minimum limit of 3000 ultimate elongation at 23°C. All of the cured compound hardness values did exceed the minimum limit of 70 as determined using a hand-held Durometer (Type A) manufactured by the Shore Instrument and Manufacturing Co., NYC.
Examples 9-16 include 100 parts of a low mooney, amorphous EPDM
terpolymer, from about 15 to 35 parts N-650 HiStr GPF black, about 17.5 parts coal filler (Example 16 only), from about 37 to 49 parts paraffinic process oil, about 15 parts chlorinated paraffin oil (Examples 9-11), from about 160 to 170 parts of a mixture of alumina trihydrate and magnesium hydroxide, from about 65 to 100 parts of either a LLDPE or HDPE resin and 55 to 100 parts of a cryogenically ground EPDM rubber (80 mesh) and the same sulfur vulcanizing accelerators as used in Examples 1-8. These Examples also displayed excellent unaged physical properties.
Tensile strength values for Examples 9-16 ranged between 1000 and 1390 psi, while the die C tear properties at 23°C were 233 (bs./inch or higher. The elongation at break values easily exceed the minimum limit of 300% ultimate elongation at 23°C. All of the cured compound hardness values easily exceed the minimum limit of 70 as determined using a hand-held Durometer (Type A) manufactured by the Shore Instrument and Manufacturing Co., NYC. Reducing the level of paraffinic process oil did not have a significant influence on LOI
determinations in Examples 9-16. Also, varying the concentrations of ATH and magnesium hydroxide had virtually no influence on cure rate at 160°C
and LOI
test results, while increasing the level of HDPE increased both die C tear resistance as well as compound hardness. Examples 9-16 easily exceeded the LOI
minimum limit of 30 when tested in accordance with ASTM D 2863-91.
Thus it should be evident that the roofing shingles and method for covering a roof, according to the present invention, are highly effective in 9707045(176) 3 6 providing long term weatherability and high durometer. The invention is particularly suited for replacing asphalt roofing shingles, but is not necessarily limited thereto. The roofing shingles and method of the present invention can also be used to replace essentially any hard, natural material previously used as a roof covering element on a sloped roof.
Based upon the foregoing disclosure, it should now be apparent that the use of the roofing shingle described herein will carry out the objects set forth hereinabove. It is, therefore, to be understood that any variations evident fall within the scope of the claimed invention and thus, the selection of specific component elements can be determined without departing from the spirit of the invention herein disclosed and described. In particular, any fillers or processing aid utilized according to the present invention are not necessarily limited to those utilized in the examples. Rather, other fillers and processing aids, or any other ingredient disclosed but not utilized in the specific examples can be utilized in the present invention, the invention not being limited by the scope of these examples or the preferred embodiment. Instead, the scope of the invention shall include all modifications and variations that may fall within the scope of the attached claims.

Claims

1. A roof covering element for use on sloped roofs, the covering element comprising:
100 parts by weight of at (east one ethylene-propylene-diene terpolymer;
and from 0 to about 120 parts by weight of at least one impact modifying polymer, per 100 parts by weight ethylene-propylene-diene terpolymer; said covering element having an unaged Shore "A" hardness at about 23°C of at least 70.

2. The roof covering element, as set forth in claim 1, wherein said at least one ethylene-propylene-diene terpolymer includes from about 80 to 100 parts by weight of at least one EPDM containing up to about 2 percent crystallinity and from 0 to about 20 parts by weight of at least one EPDM
containing more than 2 percent crystallinity.

3. The roof covering element, as set forth in claim 2, wherein said at least one ethylene-propylene-diene terpolymer includes from about 95 to 100 parts by weight of at least one EPDM containing up to about 1.1 percent crystallinity and from 0 to about 5 parts by weight of at least one EPDM
containing more than 1.1 weight percent crystallinity.

4. The roof covering element, as set forth in claim 1, wherein said at least one impact modifying polymer is at least one polyolefin resin selected from the group consisting of polyethylene, polypropylene, copolymers of ethylene and propylene, copolymers of ethylene and butene, and copolymers of ethylene and octene.

5. The roof covering element, as set forth in claim 1, wherein the covering element contains from 0 to about 50 parts by weight of said at least one impact modifying polymer, per 100 parts by weight ethylene-propylene-diene terpolymer.

6. The roof covering element, as set forth in claim 1, wherein said covering element has a limiting oxygen index of at least 30 when tested in accordance with ASTM D2863-91.

7. The roof covering element, as set forth in claim 6, wherein said covering element is a roofing shingle and has a "Class A" fire rating accordingly to UL 790 spread-of-flame test conducted by Underwriter Laboratories.

8. The roof covering element, as set forth in claim 1, further comprising:
from about 50 to about 600 parts by weight of at least one filler selected from the group consisting of combustible and non-combustible materials and mixtures thereof, per 100 parts by weight of the ethylene-propylene-diene terpolymer; and from about 30 to about 105 parts by weight of a processing material, per 100 parts by weight of the ethylene-propylene-diene terpolymer.

9. The roof covering element, as set forth in claim 8, wherein said at least one filler includes at least one organic combustible material selected from the group consisting of carbon black and ground coal.

10. The roof covering element, as set forth in claim 8, wherein said at least one filler includes at least one non-combustible material selected from the group consisting of cryogenically or ambiently ground rubber, and mineral fillers.

11. The roof covering element, as set forth in claim 10, wherein said mineral fillers are selected from the group consisting of clay, mica, talc, alumina trihydrate, antimony trioxide, calcium carbonate, titanium dioxide, silica, magnesium hydroxide, calcium borate ore, and mixtures thereof.

12. The roof covering element, as set forth in claim 8, wherein said at least one processing aid includes at least one processing oil or wax selected from the group consisting of paraffinic oils, naphthenic oils, and liquid halogenated paraffins.

13. The roof covering element, as set forth in claim 8, wherein said at least one processing aid includes an additive selected from the group consisting of at least one aromatic hydrocarbon resin and a phenolic resin.

14. The roof covering element, as set forth in claim 8, wherein said at least one filler includes a flame retardant package containing antimony trioxide and an ethylene-propylene-diene terpolymer.

15. The roofing covering element, as set forth in claim 8, further comprising from about 1.5 to about 10 parts by weight of a cure package, per 100 parts by weight of the ethylene-propylene-diene terpolymer.

16. A roofing shingle comprising:
a polymeric component comprising from at least 45 to 100 percent by weight of at least one ethylene-propylene-diene terpolymer; and from 0 up to 55 percent by weight of at least one impact modifying polymer, wherein the roofing shingles contains 100 parts by weight of at least one ethylene-propylene-diene terpolymer;
from about 50 to about 600 parts by weight of at least one filler selected from the group consisting of combustible and non-combustible fillers, per 100 parts by weight ethylene-propylene-diene terpolymer; and from about 30 to about 105 parts by weight of at least one processing material, per 100 parts by weight ethylene-propylene-diene terpolymer;
wherein the roofing shingle has a Shore "A" hardness of at least 70.

17. The roofing shingle, as set forth in claim 16, wherein said at least one ethylene-propylene-diene terpolymer includes from about 80 to 100 parts by weight of at least one EPDM containing up to about 2 percent crystallinity and from 0 to about 20 parts by weight of at least one EPDM
containing more than 2 percent crystallinity.

18. The roofing shingle, as set forth in claim 17, wherein said at least one ethylene-propylene-diene terpolymer includes from about 95 to 100 parts by weight of at least one EPDM containing up to about 1.1 percent crystallinity and from 0 to about 5 parts by weight of at least one EPDM
containing more than 1.1 percent crystallinity.

19. The roofing shingle, as set forth in claim 16, wherein said at least one impact modifying polymer is at least one polyolefin resin selected from the group consisting of polyethylene, polypropylene, copolymers of ethylene and propylene, copolymers of ethylene and butene, and copolymers of ethylene and octene.

20. The roofing shingle, as set forth in claim 16, wherein the roofing shingle contains from 0 to about 50 parts by weight of said at least one impact modifying polymer, per 100 parts by weight ethylene-propylene-diene terpolymer.

21. The roofing shingle, as set forth in claim 16, wherein said roofing shingle has a limiting oxygen index of at least 30 when tested in accordance with ASTM D2863-91.

22. The roofing shingle, as set forth in claim 21, wherein said roofing shingle has a "Class A" fire rating accordingly to a UL 790 spread-of-flame test conducted by Underwriter Laboratories.

23. A method for covering a sloped roof, comprising:
placing a plurality of roofing shingles on the roof in a preselected installation pattern, each roofing shingle including 100 parts by weight of at (east one ethylene-propylene-diene terpolymer; and from 0 to about 120 parts by weight of at least one impact modifying polymer, per 100 parts by weight ethylene-propylene-diene terpolymer; said roofing shingle having an unaged Shore "A" hardness at about 23°C of at least 70.

24. The method, as set forth in claim 23, wherein said at least one ethylene-propylene-diene terpolymer includes from about 80 to 100 parts by weight of at least one EPDM containing up to about 2 percent crystallinity and from 0 to about 20 parts by weight of at least one EPDM containing more than 2 percent crystallinity.

25. The method, as set forth in claim 24, wherein said at least one ethylene-propylene-diene terpolymer includes from about 95 to 100 parts by weight of at least one EPDM containing up to about 1.1 percent crystallinity and from 0 to about 5 parts by weight of at least one EPDM containing more than 1.1 weight percent crystallinity.

26. The method, as set forth in claim 23, wherein said at least one impact modifying polymer is at least one polyolefin resin selected from the group consisting of polyethylene, polypropylene, copolymers of ethylene and propylene, copolymers of ethylene and butene, and copolymers of ethylene and octene.

27. The method, as set forth in claim 23, wherein said roofing shingle contains from 0 to about 50 parts by weight of said at least one impact modifying polymer, per 100 parts by weight ethylene-propylene-diene terpolymer.

28. The method, as set forth in claim 23, wherein said roofing shingle has a limiting oxygen index of at least 30 when tested in accordance with ASTM
D2863-91.

29. The method, as set forth in claim 28, wherein said roofing shingle has a "Class A" fire rating accordingly to UL 790 spread-of-flame test conducted by Underwriter Laboratories.

30. The method, as set forth in claim 23, further comprising:
from about 50 to about 600 parts by weight of at least one filler selected from the group consisting of combustible and non-combustible materials and mixtures thereof, per 100 parts by weight of the ethylene-propylene-diene terpolymer; and from about 30 to about 105 parts by weight of a processing material, per 100 parts by weight of the ethylene-propylene-diene terpolymer.

31. The method, as set forth in claim 30, wherein said at least one filler includes at least one organic combustible material selected from the group consisting of carbon black and ground coal.

32. The method, as set forth in claim 30, wherein said at least one filler includes at least one non-combustible material selected from the group consisting of cryogenically or ambiently ground rubber, and mineral fillers.

33. The method, as set forth in claim 32, wherein said mineral fillers are selected from the group consisting of clay, mica, talc, alumina trihydrate, antimony trioxide, calcium carbonate, titanium dioxide, silica, magnesium hydroxide, calcium borate ore, and mixtures thereof.

34. The method, as set forth in claim 30, wherein said at least one processing material includes at least one processing oil or paraffin selected from the group consisting of paraffinic oils, naphthenic oils, and liquid halogenated paraffins.

35. The method, as set forth in claim 30, wherein said at least one processing aid includes an additive selected from the group consisting of at least one aromatic hydrocarbon resin and a phenolic resin.

36. The method, as set forth in claim 30, wherein said at least one filler includes a flame retardant package containing antimony trioxide and an ethylene-propylene-diene terpolymer.

37. The method, as set forth in claim 30, further comprising from about 1.5 to about 10 parts by weight of a cure package, per 100 parts by weight of the ethylene-propylene-diene terpolymer.