CA1148039A - Sulfur-based roof shingles - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Sulfur-based roof shingles which consist essentially of a fibrous base mat coated on at least one surface with a plasticized-sulfur composition were found to have surprising flexibility and fire resistance when compared to similar asphalt shingles.

Description

~48~39 005The invention concerns the use of plasticized sulfur 006 to prepare a flexible, fire-resistant roof shingle. In the 007 past, the relative economics of asphalt and sulfur would not 008 have suggested the usefulness of sulfur technology in the roof 009 shingle industry. However, the recent availability of sulfur 010 and the increased cost of petroleum-derived products have led 011 to a variety of reasons to consider the application of sulfur.
012 Despite the economic incentives, the use of sulfur in 013 roof shingles has been slow in developing due to a number of 014 serious shortcomings. In particular, sulfur is an extremely 015 brittle solid and will not withstand the stresses to which a 016 roof shingle is subjected. For example, a roof shingle is 017 nailed into position. Shingles made from sulfur must be 018 pre-drilled to avoid splitting when nailed. In many applica-019 tions, roof shingles need to be flexible enough to withstand 020 the weight of a heavy snowfall at sub-zero temperatures.
021 Again, shingles made from sulfur have not been strong enough to 022 withstand considerable weight.
023 Perhaps the most serious shortcoming concerns the 024 combustibility of sulfur. Sulfur roofing materials burn with 025 excessive melting of the sulfur, which in turn flows and drips, 026 transporting the fire with it. Thus, the fire is spread to 027 other areas of the structure. Moreover, burning sulfur 028 generates large amounts of sulfur oxides, posing a severe 029 pollution problem.

030 Some attempts have been made to reduce the combusti-031 bility of sulfur by incorporating various flame retardants into 032 the sulfur. For example, U.S. Patent 1,835,767, granted 033 December 8, 1931, describes the use of sulfur resins to retard , ~...
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~81:)39 002 the combustion of sulfur. However, when the composition is 003 applied to a fibrous or paper backing the laminated product 004 loses its flexibility, becoming very stiff. Similarly, Dale 005 and Ludwig, "Fire-Retarding Elemental Sulfur~, Journal of 006 Materials, Vol. 2, No. 1, March 1967, p. 131, describe the 007 effect of a variety of ~aterials on the combustibility of 008 sulfur with either styrene or dipentene dimercaptan. The 009 ~fire-proof~ compositions were suggested as wall coatings, 010 presumably because they form a firm, inflexible coating.
011 Attempts have been made to prepare flexible 012 cloth-like products using plasticized sulfur as a third coating 013 over the product. U.S. Patent 3,619,258, granted November 9, 014 1971, to Bennett, and U.S. Patent 3,721,578, granted March 20, 015 1973, to Bennett describe the use of thin coatings of plasti-016 cized-sulfur compositions over an asphalt-impregnated fabric to 017 prepare a flexible, water-proof product. The thin coating of 018 plasticized sulfur is used to improve the weather-proof 019 characteristics of the final product.

021 It has now been found tha~ a non-asphaltic sulfur-022 based roof shingle consisting essentially of a fibrous base mat 023 impregnated with a plasticized-sulfur composition comprising 024 from about 30 to 98% sulfur exhibits good fire resistance and 025 flexibility.

027 The roof shingles of this invention do not contain 028 asphalt and can be prepared using conventional manufacturing 029 approaches. ~owever, the preferred method of manufacture is 030 the dipping process typically used to manufacture conventional 031 asphalt shingles. According to the method, a stàndard fibrous 032 mat is run continuously through a dryer and is fed into a vat 033 of molten asphalt-free plasticized-sulfur composition to ~1~8~3~

001 ~3~

002 saturate the mat and insure its impregnation. The saturated 003 mat is squeezed between rollers to insure uniform thickness.
004 Roofing granules are applied, and the mat is run through a 005 water-cooled press roller. Finally, the mat is cut to the 006 desired shape.
007 The fibrous base mat can be any of the standard 008 shingle mats. Suitable mats include those used in the 009 production of asphalt shingles. Presently most shingles are 010 prepared using either glass fiber mats or cellulose fiber mats, 011 and these mats are preferred. Glass fiber mats offer 012 additional fire resistance, and are especially preferred.
013 Binders may be added to the fibrous mat or the thickness of the 014 mat can be varied to improve strength. Good results have been 015 obtained using a 6.0 gram per square foot glass fiber mat with 016 polystyrene binder.
017 Any suitable plasticized-sulfur composition free of 018 asphalt but containing sulfur, plasticizer, and, optionally, 019 fillers, pigments, dyes, and the like, can be used. Suitable 020 plasticized-sulfur compositions preferably contain at least 021 30%, by weight, sulfur. In general, the compositions are 022 composed of from about 30% to 98% sulfur, from about 0.2% to 023 20% plasticizer, and from about 1 to about 70% filler.
024 Preferably the compositions contain from 50% to 85% sulfur, 025 from 1% ~o 5% plasticizer and from 10% to 49% filler.
026 Fillers for use in this composition include fibers 027 such as those made from glass, asbestos, carbon, etc.; particu-028 late solids such as sand, hydrated alumina, mica, calcium 029 carbonate, talc, ammonium polyphosphate, clay, calcium sulfate, 030 antimony oxide, borax, zinc borate, titanium dioxide, iron 031 oxide, molybdenum trioxide, magnesium hydroxide, ferric 032 chloride, etc.; inert, high-melting, fire-retardant organic 033 compounds, in particular those that are essentially insoluble ~148~39 in sulfur, especially halogenated cyclopentadiene oligomers and haloaromatics such as tetrabromophthalic anhydride, and halogenated bisphenols, e.g., tetrabromobisphenol-A.
Especially preferred plasticized-sulfur compositions are described in United States Patent No. 4,026,719, issued May 31, 1977. The plasticized-sulfur compositions of that application include, in addition to sulfur and plasticizer, mica as a filler. In general, the compositions are composed of from about 50% to 98% sulfur, from about 0.2% to 20% plasticizer, and from 5%
to 20% mica.
The plasticized-sulfur composition is usually prepared in molten form by adding the plasticizer to molten sulfur and heating the resulting mixture at a temperature above the melting point, e.g., at a temperature between 110 C and 180 C, preferably between about 125 C and 150 C. Fillers, pigments, flame retardants, etc., are then added, and the resulting composi-tion is mixed until homogenous. It is then used to impregnate shingle mats as described above.
The composition also includes a sulfur plasticizer. A sulfur plasticizer is used to mean something that plasticizes sulfur or results in plasticized sulfur. In turn, "plasticized sulfur" as the term is used herein usually has a slightly lower melting point than elemental sulfur.
Furthermore, plasticized sulfur requires a longer time to crystallize; i.e., the rate of crystallization of plasticized sulfur is slower than that of elemental sulfur. One useful way to measure the rate of crystallization is as follows: the test material (0.040 g) is melted on a microscope slide at 130 C and is then covered with a square microscope slide cover slip. The slide is transferred to a hot plate and is kept at a temperature of 78+2 C, as 11 ~8;r339 001 ~5~

002 measured on the glass slide using a surface~pyrometer. One 003 corner of the melt is seeded with a crystal of test material.
004 The time required for complete crystallization is measured.
005 Plasticized sulfur, then, is sulfur containing an additive 006 which increases the crystallization time within experimental 007 error, i.e., the average crystallization time of the plasti-008 cized sulfur is greater than the average crystallization time 009 of the elemental sulfur feedstock. For the present applica-010 tion, plasticizers are those substances which, when added to 011 molten elemental sulfur, cause an increase in crystallization 012 time in reference to the elemental sulfur itself.
013 Inorganic plasticizers include iron, arsenic and 014 phosphorus sulfides, but the particularly preferred plasti-015 cizers are organic compounds which react with sulfur to give 016 sulfur-containing materials. -- -017 Sulfur plasticizers which are suitable include 018 aliphatic polysulfides, aromatic polysulfides, styrene, dicyclo-019 pentadiene, dioctylphthalate, acrylic acid, epoxidized soybean 020 oil, triglycerides, and tall oil fatty acids.
021 One class of preferred plasticizers is the aliphatic 022 polysulfides, particularly those that will not form cross-023 linking. Thus butadiene is not a preferred constituent to form 024 the aliphatic polysulfide, as it may form cross-linking sulfur 025 bonds, whereas dicyclopentadiene is a preferred compound for 026 forming the aliphatic polysulfide useful as the sulfur 027 plasticizer. With molten sulfur, dicyclopentadiene forms an 028 extremely satisfactory aliphatic polysulfide.
029 Another class of preferred plasticizers for use in 030 the compositions are aromatic polysulfides formed by reacting 031 one mol of an aromatic carbocyclic or heterocyclic compound, 032 substituted by at least one functional group of the class -OH
Q33 or -NHR ln which R is H or lower alkyl with at least two mols 034 of sulfur.

002 Suitable aromatic compounds of this type include:
003 phenol, aniline, N-methyl aniline, 3-hydroxy thiophene, 004 4-hydroxy pyridine, p-aminophenol, hydro~uinone, resorcinol, 005 meta-cresol, thymol, 4,4!-dihydroxy biphenyl, 2,2-di(p-hydroxy-006 phenol)propane, di(p-hydroxy phenyl)methane, etc., p-phenylene 007 diamine, methylene, dianiline. Phenol is an especially 008 preferred aromatic compound to form the aromatic polysulfide.
009 The aromatic polysulfides are generally prepared by 010 heating sulfur and the aromatic compound at a temperature in 011 the range of 120 to 170C for 1 to 12 hours, usually in the 012 presence of a base catalyst such as sodium hydroxide. (See for 013 example, Angew, Chem. ~70, No. 12, pages 351-67 (1958)). The 014 polysulfide product made in this way has a mol ratio of 015 aromatic compound:sulfur of 1:2 to 1:10, preferably from 1:3 to 016 1:7. Upon completion of the reaction, the caustic catalyst is 017 neutralized with an acid such as phosphoric or sulfuric acid.
018 Organic acids may also be used for this purpose. The resulting 019 aromatic polysulfide may be used immediately or it may be 020 cooled and stored for future use.
021 Another type of aliphatic polysulfide useful as a 022 plasticizer is the linear aliphatic polysulfides. Although 023 these polysulfides may be used alone as the sulfur plasticizer, 024 it is preferred to use them in combination with either (a) di-025 cyclopentadiene or (b) the aromatic polysulfides described 026 above, especially with the phenol-sulfur adduct. In this 027 connection, the preferred plasticizer mixtures contain from 5 028 to 60% linear aliphatic polysulfide by weight based on total 029 plasticizer, preferably about 10 to 30 weight percent.
030 These aliphatic polysulfides may have branching 031 indicated as follows:

033 --C=C+S> --S--C--C--S

~48333~

002 wherein x is an integer of from 2 to 6 and wherein B is H, 003 alkyl, aryl, halogen, nitrile, ester or amide group. Thus in 004 this connection the aliphatic polysulfide is preferably a 005 linear polysulfide. The chain with the sulfur preferably is 006 linear, but it can have side groups as indicated by "B" above.
007 Also, this side grouP "B" may be aromatic. Thus styrene can be 008 used to form a phenyl substituted linear aliphatic polysulfide.
009 The preferred aliphatic polysulfides of this type are both 010 linear and non-branched.
011 Unbranched linear aliphatic polysulfides include 012 those such as Thiokol LP-3 which contains an ether linkage and 013 has the recurring unit:

015 -SxcH2cH2OcH2ocH2c~2sx 017 wherein x has an average value of about 12. The ether consti-018 tuent of this aliphatic polysulfide is relatively inert to 019 reaction. Other suitable aliphatic polysulfides have the 020 following recurring units:

022 -SX~CH2tySx~ from reaction of ~ -dihaloalkanes and 023 sodium polysulfide 024 -SX~CH2CH2-s-cH2cH2tsx- from reaction of a ,~ -dihalo-025 sulfides and sodium polysulfide 026 -sxtcH2cH2-o-cH2cH2tsx- from reaction of a ,~-dihalo-027 esters and sodium polysulfide 028 wherein x is an integer of 2 to 5; and y is an integer of 2 to 029 10.
030 Mica is an important element of the preferred plasti-031 cized-sulfur compositions. The term "mica" is used herein to 032 mean a layered silicate having an x-ray diffraction pattern d 033 spacing about 9.6 to 10.1 A, preferably a d spacing of about 034 9.9 to 10.1 A. Talc material also is a layered silicate, but 1~8~339 001 -8~

002 has a d spacing of about 9.35 A. Satisfactory mica particles 003 cover a very broad range of sizes. It is preferred that at 004 least 90~ pass through a 40-mesh (Tyler) screen. Satisfactory 005 particles have sizes ranging in diameter from 0.001 to 2 mm and 006 in thickness from 0.0005 to 0.2 mm.
007 Typical amounts of mica in the formulation are about 008 1 to 40 weight percent, preferably 5 to 30 weight percent, and 009 particularly preferred amounts are 10 to 20 weight percent.
010 Preferred micas for use in the composition of the 011 present invention are phlogopite, muscovite, zinnwaldite and 012 biotite, which are natural micas, and fluorophlogopite and 013 barium disilic, which are synthetic micas.
014 Particularly preferred micas for use in the present 015 invention contain potassium and have a chemical composition of 016 3A13O3-K2~6SiO2-2H2O, also written R2A14(A12Si6O20)(OH)4. Mica 017 differs from talc in that talc typically does not contain 018 potassium. Kirk-Othmer Encyclopedia of Chemical Technology, 2d 019 Ed., Vol. 19, page 608, gives the following chemical formula 020 for talc: Mg3SiO10(OH)2.
021 In order to give the sulfur-based shingles of the 022 present invention a conventional appearance, standard roofing 023 granules of various colors can be applied to the shingle while 024 the plasticized-sulfur composition is still tacky. Any 025 suitable roofing granule can be used, such as those presently 026 available from the Industrial Mineral Products Division of the 027 3M Company. Since all that is seen of any shingle after it is 028 attached to a roof is the top, sulfur-based shingles having 029 roofing granules embedded on the top surface have much the same 030 general appearance as asphalt shingles even though the sulfur-031 based shingles contain no asphalt. A small amount of dye, such 032 as carbon black, could even be used to make the plasticized 033 sulfur appear as conventional asphalt.

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~81:)39 001 -9_ 003The following examples illustrate the invention and 004 are not intended to limit the scope of the claims which follow.
005 Example 1 006 The standard method of rating roofing coverings for 007 fire resistance is ASTM E-108, "Fire Tests of Roof CoveringsR.
008 Using a scaled-down version of this test, so that smaller roof 009 test decks could be used and combustibility of the shingles 010 could be examined as limiting factor, test roof decks 22" wide 011 by 4' long were constructed from 2~x4~ rafters covered with 012 1/2~ plywood decking. These were covered with conventional 013 15-pound asphalt-impregnated roofing felt.
014 Sulfur-based shingles 12~ wide by 22~ long were hand-015 cast using the plasticized-sulfur compositions of Table I with 016 one thickness of fiber glass mat and a top coating of roofing 017 granules.

019Plasticized-Sulfur Compositions 022 Sulfur, % 84 61.9 61 4981.5 023 Dicyclopentadiene, % 2 2.0 2 1 1.0 024 Mica, % 12 5.0 5 -- 17 025 Glass Fiber, % 2 2.0 2 2 026 Sand (120 mesh), % -- -- -- 24 027 Hydrated alumina, ~ -- 25.0 30 24 028 Tetrabromophthalic anhydride, % -- 3.6 -- --029 Ammonium polyphosphate, % -- 0.5 -- --030 Thiokol LP-3, % -- -- -- -- 0.5 031 The shingles had the following approximate 032 composition by weight:
033 Glass Fiber 12 grams 034 Plasticized Sulfur 780 grams 035 Granules 440 grams 036 Total 1232 grams ~., 1~48~39 002 Conventional Class C asphalt shingles of the same 003 dimensions weigh approximately 1300 grams. Thus, for all 004 intents and purposes, the non-asphaltic sulfur-based shingles 005 of this invention are comparable to Class C asphalt shingles.
006 Each of the four types of sulfur-based shingles A-D
007 was then nailed onto a test roof deck with conventional 008 aluminum roofing nails, using the standard 6 n overlap method.
009 For comparison, shingles made of pure sulfur were also nailed 010 to a test deck. These shingles were extremely brittle and 011 cracked badly on nailing, such that pre-drilling of the nail 012 holes was necessary. Similarly, test decks were covered with 013 wooden cedar shake shingles and Class C asphalt shingles.
014 A fire test apparatus was constructed of the same 015 basic design used in ASTM E-108. The air velocity, burner 016 capacity, flame size, and eave design were suck that the flame 017 played uniformly over the top surfaces of the test decks.
018 An exposure time of 18.5 minutes was set, based upon 019 preliminary tests indicating that burning on the most 020 combustible shingles, cedar shake, had proceeded through the 021 shingles, felt, and plywood after 18.S minutes.
022 The results of this test are summarized below, pro-023 ceeding from the worst performance to the best.
024 Wooden Cedar Shake Shingle Deck 025 This roofing material burned with great intensity.
026 Flames extended 2' beyond the top edge of the roof. The roof 027 temperature quickly stabilized at 871C, and large amounts of 028 white smoke were produced. The plywood decking that was not 029 burned through was badly charred.
030 Asphalt Shingle Deck 031 This roofing material burned with slightly less inten-032 sity than the wooden cedar shake roof, but flames still ¢33 extended 2' beyond the top edge of the roof. The roof tempera-`\

~8V39 002 ture quickly stabilized at 787C and large amounts of black 003 smoke were produced. The plywood decking was badly charred, 004 and there was one small 2" hole burned through it.
005 Sulfur Shingle Deck 006 This roofing material burned with excessive melting 007 of the sulfur, which in turn flowed and dripped over the eave, 008 transporting the fire with it and spreading the fire. The 009 temperàture quickly stabilized at 565C and finally there was a 010 small amount of white smoke and very little visible flame. SO2 011 generation was extreme. There was some charring of the plywood 012 deck.
013 Compositions A, B, C and D Shingle Decks 014 The performances of the test decks made with shingles 015 from the different plasticized-sulfur compositions of the 016 invention were very similar. Time to reach ig~ition, time to 017 burning the full length of the roof and time for the roof 018 temperature to stabilize were generally longer than for the 019 other roofs, in some cases by a factor of 2. There was no 020 running or dripping of the roofing material, as experienced 021 with the asphalt or pure sulfur roofs. The roofs did not burn 022 with intensity, and there were no extending flames. The roof 023 temperature stabilized at approximately 565C, which was 287C
024 and 20ioC less than for the cedar and asphalt roofs, 025 respectively. There was a small amount of white smoke and very 026 little visible flame. SO2 generation was not extensive, as 027 with the pure sulfur roof. There was no charring of the 028 plywood roof decks.

~8~39 003 Asphalt Shingle Deck 005 Min. Temp. C
007 2.5 - Asphalt melted & bubbling full length of roof 427 008 4.0 - Ignition at bottom of roof 649 009 5.0 - Burning full length of roof with excessive 010 dripping asphalt 759 011 13.0 - Burning full length of roof with excessive 012 dripping asphalt 787 013 18.5 - Stopped test 787 015 Cedar Shake Deck 016 Min. Temp. C
018 (1) 1.0 - Ignition at bottom 593 ~19 (2) 1.5 - Burning full length 649 020 (3) 4.5 - Burning full length 705 021 (4) 6.5 - Burning full length 871 022 (5) 12.0 - Burning full length 871 023 (6) 18.5 - Burned through 871 025 Pure Sulfur Deck 026 Min. Temp. C
028 (1) 1.0 - Melting on surface 343 029 (2) 1.5 - Ignition at bottom of roof 538 030 (3) 4.0 - Burning full length of roof. Excessive 031 melted yellow sulfur running and dripping 565 032 (4) 7.0 - Excessive melted, black sulfur running down 033face of roof and off eave 565 034 (5) 12.0 - Running and dripping stopped 565 035 (6) 18.5 - Stopped test 565 037Composition A Deck 038 Min. Temp. C
0401.5 - Ignition at bottom of roof 477 0414.0 - Burning full length of roof 538 0427.n - Burning full length of roof 565 04312.0 - Burning full length of roof 574 04414.5 - Burning full length of roof 565 04518.5 - Burning full length of roof 565 047Composition B Deck 048 Min. Temp. C
0502.0 - Ignition at abottom of roof 399 0513.0 - Burning full length of roof 427 0527.0 - Burning full length of roof 593 05312.0 - Burning full length of roof 649 05414.5 - Burning full length of roof 677 05518.5 - Burning full length of roof 677 057Composition C Deck 058 Min. Temp. C
0594.0 - Ignition at bottom of roof 427 0605.0 - Burning full length of roof 477 0617.0 - Burning full length of roof 565 06212.0 - Burning full length of roof 565 06314.5 - Burning full length of roof 565 06418.5 - Burning full length of roof 593 8~39 002 Composition D Deck 004 Min. Temp. C
005 ~~ - Ignition 427 0066.0 - Burning full length of roof 538 0079.0 - Burning full length of roof 574 00812.0 - Burning full length of roof 565 00914.5 - Burning full length of roof 565 01018.5 - Burning full length of roof 565 012 From this series of tests, it was concluded that from 013 the standpoint of fire resistance the sulfur-based shingles 014 were better than wooden cedar shingles or Class C asphalt 015 shingles as used in residential construction. From these 016 tests, it is reasonable to assume that plasticized sulfur-based 017 shingles should easily pass ASTM E-1~08 requirements and offer a 018 measure of fire resistance to residential construction now only 019 available in specialized grades of shingles. It is possible to 020 further improve the fire resistance of the formulations by 021 incorporating additives into them. It is also possible to 022 improve the fire resistance of the shingles made from these 023 compositions by the use of exterior coatings over them. Thus, 024 there are a variety of ways to improve upon the fire retardancy 025 of the sulfur-based shingles within the scope of this 026 invention.
027 Example 2 028 Using the following method, various sulfur-based roof 029 shingles were prepared and screened for ease of handling and 030 workability.
031 One or more layers of glass fiber mat were clamped 032 between two 1/2N square aluminum bars. This flag of glass 033 fiber mat was then dipped into the vat of molten sulfur 034 Composition E that was maintained at a temperature of 150C.
035 After immersion for approximately 10 minutes with movement to 036 obtain saturation, the mat was removed. Upon removal there was 037 excess sulfur formulation on the mat. The mat was then 03~ released from the holding bars, put on a hot sheet of oiled ` .oJ

~48~39 002 aluminum and placed in an oven. When the mat and the sheet had 003 all stabilized at 150C, it was removed from the oven along 004 with a 3n-diameter aluminum roller which was also at 150C.
005 The mat was then rolled to remove the excess sulfur coating 006 compound to provide a uniform thickness and a smooth surface.
007 After rolling there is very little excess sulfur compound on 008 the top, such that the mat structure impregnated with the 009 plasticized-sulfur composition is visible just as the mat 010 structure is visible on the bottom of an asphalt shingle. At 011 this point, the top of the plasticized-sulfur based shingle 012 became the bottom of the shingle as it was turned over and the 013 roofing granules were applied in excess, after which the 014 shingle was returned to the oven and again U15 temperature-stabilized at 15~C to allow the granules to imbed 016 themselves in the sulfur formulation. The compositions of the 017 shingles prepared using this method are summarized below:

018 As~halt Shingle (Class C - Residential) 020 Paper Felt 30 grams 021 Asphalt 210 grams 022 Granules 217 grams 023 Total 457 grams 025 Sulfur-Based Shingle One-Layer Mat - No Granules 027 One glasc fiber mat 6 grams 028 Composition E 140 grams 029 Total 146 grams 031 Sulfur-Based_Shingle Two-Layer Mat - No Granules 033 Two glass fiber mats 12 grams 034 Composition E 193 grams 035 Total 205 grams 037 Sulfur-Based Shingle Three-Layer Mat - ~o Granules 039 Three glass fiber mats 18 grams 040 Composition E 262 grams 041 Total 280 grams 043 Sulfur-Based Shingle One-Layer Mat - Granules 045 One glass fiber mat6 grams 046 Composition E 202 grams 047 Granules 121 grams 048 Total329 grams ~8-~39 Oo~ Sulfur-Based Shingle Two-Layer Mat - Granules 004 Two glass fiber mats 12 grams 005 Composition E 256 grams 006 Granules 110 grams 007 Total 378 grams 009 Sulfur-Based Shingle Three-Layer Mat - Granules 011 Three glass fiber mats 18 grams 012 Composition E ' 502 grams 013 Granules 216 grams 014 Total 736 grams 016 These shingles present a range of properties from a 017 very thin and flexible shingle to a heavy, rigid shingle. ~hey 018 indicate that there is considerable latitude in the 019 construction of shingles with the use of the plasticized-sulfur 020 compositions. Since the use of mat and granules is essentially 021 comparable to what is used in Class C asphalt shingles, the 022 major difference between the two is the superior fire 023 resistance of the plasticized sulfur-based shingles. A unique 024 and unexpected feature of the sulfur-based shingles is their 025 flexibility. They have virtually the same degree of flexi-026 bility as asphalt shingles.

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A non-asphaltic sulfur-based roof shingle having good fire resist-ance consisting essentially of a fibrous base mat impregnated with a plasti-cized-sulfur composition comprising from about 30% to about 98% by weight sulfur.

2. A roof shingle according to claim 1 which has a layer of roofing granules embedded in the plasticized-sulfur composition.

3. A roof shingle according to claim 1 wherein the plasticized-sulfur composition comprises from about 30 to 98% by weight sulfur, from about 0.2 to 20% by weight plasticizer, and from about 1 to 70% by weight filler.

4. A roof shingle according to claim 3 wherein the plasticizer is dicyclopentadiene.

5. A roof shingle according to claim 3 wherein the filler is selected from the group consisting of mica, hydrated alumina, glass fiber, and mix-tures thereof.

6. A roof shingle according to claim 1 wherein the plasticized-sulfur composition comprises sulfur, dicyclopentadiene, mica and glass fiber.

7. A roof shingle according to claim 1 wherein the plasticized-sulfur composition comprises sulfur, dicyclopentadiene, mica, glass fiber, hydrated alumina, tetrabromophthalic anhydride and ammonium polyphosphate.

8. A roof shingle according to claim 1 wherein the plasticized-sulfur composition comprises sulfur, dicyclo-pentadiene, mica and glass fiber.

9. A roof shingle according to Claim 1 wherein the plasticized-sulfur composition comprises sulfur, dicyclo-pentadiene, glass fiber, sand and hydrated alumina.

10. A roof shingle according to Claim 1 wherein the shingle has a final thickness of at least 50 mil.