Flame retardant asphalt composition

Abstract: Disclosed is a fire retardant asphalt composition. The composition comprises: (a) about 40-60% wt asphalt; (b) about 1-20% wt thermoplastic; (c) about 15-40% wt flame retarding agent; and (d) the flame retarding agent comprises: (i) about 65-95% weight ammonium sulfate, (ii) about 1% weight silicone polymer.

Description: The present invention relates to a flame retardant asphalt composition. More specifically, the invention relates to a thermoplastic modified asphalt composition that includes a flame retardant coated with a silicone polymer. Asphalt is an excellent sealing and adhesive material. As such, asphalt is used extensively in the roofing industry. All sorts of roofing materials contain asphalt, including shingles and roofing paper. Notwithstanding its excellent sealing and adhesive characteristics, asphalt has one major drawback. Asphalt is very combustible. As such, it is important to reduce the combustibility of an asphalt composition. Many localities have regulations that require roofing materials to conform to certain standards. For instance, many such regulations require that roofing materials qualify as a Class A material under UL 790 or ASTM E-108 standards. These standards measure flame spread for non-combustible based decks and flame spread and brand penetration for combustible based decks. Presently available flame retardant asphalt compositions have had difficulty in qualifying as a Class A material. Many of those that have passed include expensive and sometimes toxic ingredients. As such, the compositions are expensive and possibly dangerous. Other presently available Class A flame retardant asphalt compositions include large quantities of non-combustible inert fillers. These materials are often heavy which may cause material handling problems. Accordingly, a need exists to provide a thermoplastic modified asphalt material that is suitable for use on dwellings, schools and public facilities under the regulations now in force throughout the United States. The present invention addresses the current need for an inexpensive flame retardant asphalt composition for roofing materials. The inventive composition includes 45-65% asphalt, 1-20% of a thermoplastic and 15-40% of a flame retarding ingredient ("flame retardant"), the percentages being based on the weight. The flame retardant includes by weight 65-95% ammonium sulfate and 1-5% methyl hydrogen polysiloxane. Some inert fillers may be added to complete the composition. The composition is manufactured by mixing the asphalt and a thermoplastic at temperatures between 163-218° C (325-425° F). Next, the flame retardant is added and mixed into the modified asphalt, preferably by a paddle mixer. As such, the composition is easy to make. A major ingredient of the flame retardant is ammonium sulfate. Ammonium sulfate is soluble in water and has a tendency to leach out of compositions exposed to water. As such, ammonium sulfate has not been used as a major ingredient in a flame retardant asphalt composition. The flame retardant includes a methyl hydrogen polysiloxane ("silicone polymer") that forms a film. The film is a surface treatment that prevents water adsorption and absorption. As such, the film makes the flame retardant water repellent. The film also allows the flame retardant to withstand higher processing temperatures and UV radiation. Presently, the preferred composition costs less and performs better than the compositions claimed in applicants' U.S. Patent No. 4,804,696 and co-pending application relating to a potassium citrate composition. Further advantages and features of the present invention will become apparent while reviewing the detailed description of the invention. The present invention comprises three ingredients: (1) bitumen; (2) a thermoplastic; and (3) a flame retarding agent. The bitumen ingredient preferably includes petroleum asphalt. This ingredient comprises 45-65% by weight of the composition. It is preferred that the bitumen ingredient be 58.8% of the composition. The thermoplastic ingredient is styrene-butadiene-styrene block copolymer (SBS). The thermoplastic is blended with the bitumen at temperatures between 163° C and 218° C (325 and 425° F). The flame retardant comprises between 15-40% of the composition. The ingredients of the flame retardant include 65-95% by weight ammonium sulfate and 1-5% by weight methyl hydrogen polysiloxane. The flame retardant is mixed into the thermoplastic modified bitumen. Preferably, the bitumen is maintained at 163-218° C (325-425° F) during mixing. The most preferred flame retardant is 26.5% wt of the composition and comprises by weight: (1) 93% ammonium sulfate; (2) 1% methyl hydrogen polysiloxane; (3) 3% muscovite mica; (4) 3% magnesium aluminum silicate. Such a retardant is available from Ansul Fire Protection, Inc. Ansul Fire Protection, Inc. is located in Marinette, Wisconsin. The inventive composition is conveniently made by first blending the thermoplastic with the asphalt at temperatures between 163 and 218° C (325 and 425° F). Next, the flame retardant is added to the thermoplastic modified asphalt by mixing, preferably by paddle mixers where the modified asphalt is maintained above 163° C (325° F). The inventive composition may be used in several different roofing applications and on different carriers. The composition may be used in conjunction with polyester or fiberglass reinforcements. The following example is presented to show a preferred embodiment of the invention. The preferred composition includes by weight: (1) 58.8% asphalt; (2) 14.7% styrene-butadiene-styrene; (3) 24.64% ammonium sulfate; (4) 0.26% methyl hydrogen polysiloxane; (5) 0.8% muscovite mica; and (6) 0.8% magnesium aluminum silicate. The composition has been tested by UL under UL 790 conditions. UL has awarded the preferred composition a Class A ranking. The preferred composition may be made by: (1) Heating the asphalt to 177-204° C (350-400° F); (2) Adding and mixing styrene-butadiene-styrene ("SBS") into the heated asphalt; and (3) Adding and mixing the flame retardant into the heated modified bitumen with a paddle mixer.

Claims: Claims for the following Contracting States : AT, BE, CH, LI, DE, DK, FR, GB, IT, LU, NL, SE A flame retardant asphalt composition comprising: (a) 45 - 65 % by weight asphalt; (b) 1 - 20 % by weight styrene-butadiene-styrene block copolymer (SBS); (c) 15 - 40 % by weight flame retardant; wherein the sum of the components (a), (b) and (c) is equal to 100 % by weight and wherein the flame retardant includes (i) 65 - 95 % by weight ammonium sulfate, (ii) 1 - 5 % by weight methyl hydrogen polysiloxane. A flame retardant asphalt composition comprising: (a) 58,8 % by weight bitumen; (b) 14,7 % by weight styrene-butadiene-styrene block copolymer (SBS); (c) 26,5 % by weight flame retardant, wherein the sum of the components (a), (b) and (c) is equal to 100 % by weight and wherein the flame retardant comprises: (i) 93 % by weight ammonium sulfate, (ii) 1 % by weight methyl hydrogen polysiloxane; (iii) 3 % by weight muscovite mica; and (iv) 3 % by weight magnesium aluminum silicate. Claims for the following Contracting State : ES A flame retardant asphalt composition comprising: (a) 45 - 65 % by weight asphalt; (b) 1 - 20 % by weight styrene-butadiene-styrene block copolymer (SBS); (c) 15 - 40 % by weight flame retardant; wherein the sum of the components (a), (b) and (c) is equal to 100 % by weight and wherein the flame retardant includes (i) 65 - 95 % by weight ammonium sulfate, (ii) 1 - 5 % by weight methyl hydrogen polysiloxane. A flame retardant asphalt composition comprising: (a) 58,8 % by weight bitumen; (b) 14,7 % by weight styrene-butadiene-styrene block copolymer (SBS); (c) 26,5 % by weight flame retardant, wherein the sum of the components (a), (b) and (c) is equal to 100 % by weight and wherein the flame retardant comprises: (i) 93 % by weight ammonium sulfate, (ii) 1 % by weight methyl hydrogen polysiloxane; (iii) 3 % by weight muscovite mica; and (iv) 3 % by weight magnesium aluminum silicate. A method for preparing a flame retardant asphalt composition comprising: (a) 45 - 65 % by weight asphalt; (b) 1 - 20 % by weight styrene-butadiene-styrene block copolymer (SBS); (c) 15 - 40 % by weight flame retardant; wherein the sum of the components (a), (b) and (c) is equal to 100 % by weight and wherein the flame retardant includes (i) 65 - 95 % by weight ammonium sulfate, (ii) 1 - 5 % by weight methyl hydrogen polysiloxane, said method comprising (i) mixing the asphalt and the styrene-butadiene-styrene block copolymer (SBS) in appropriate amounts; (ii) adding the flame retardant in the appropriate amount and mixing it into the modified asphalt. A method for preparing a flame retardant asphalt composition comprising: (a) 58,8 % by weight bitumen; (b) 14,7 % by weight styrene-butadiene-styrene block copolymer (SBS); (c) 26,5 % by weight flame retardant, wherein the sum of the components (a), (b) and (c) is equal to 100 % by weight and wherein the flame retardant comprises: (i) 93 % by weight ammonium sulfate, (ii) 1 % by weight methyl hydrogen polysiloxane; (iii) 3 % by weight muscovite mica; and (iv) 3 % by weight magnesium aluminum silicate, said method comprising (i) mixing the bitumen and the styrene-butadiene-styrene block copolymer (SBS) in appropriate amounts; (ii) adding the flame retardant in the appropriate amount and mixing it into the modified bitumen.

Inventors: JOLITZ RANDAL J, KIRK DONALD R, JOLITZ, RANDAL J., KIRK, DONALD R.
Applicants: TAMKO ROOFING PROD INC, TAMKO ROOFING PRODUCTS, INC.
Application year: 1990
Main classification: C08K3
IPC codes: C08L53, C08K3, C08L95, E04D7, C08L83