CA2023620A1 - Flame retardant asphalt composition - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Disclosed is a fire retardant asphalt composition.
The composition comprises:

(a) about 40-60% wt asphalt;

(b) about 1-20% wt thermoplastic;

(c) about 30-403 wt flame retarding agent; and (d) the flame retarding agent comprises:

(i) about 65-80% weight monoammonium phosphate, (ii) about 5-15% weight ammonium sulfate; and (iii) about 1% weight silicons polymer.

Variations of this composition have passed the UL 790 test for Class A flame retardant materials.

TAMA:015/C4

Description

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BACKGROUN OF T~E INVENTION

Field of the Invention The present invention relates to a flame retardant asphalt composition. More specifically, the invention relates to a thermoplastic modifi~d asphalt composition that includes a flame retardant coated with a silicone polymer.
~ackaround Asphalt is an exc~llent sealing and adhesive material. As such, asphalt is used extensively in the roofing industry. All sorts o~ 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 combu~tibility of an asphalt composition.

Many localitie~ have regulation~ that require roofing material8 to con~orm to certain standards. .~or instanee, many such regulations requlre that rooEing material~
quali~y a~ a Claqs A material under UL 790 or ~STM E-108 standards. These standards measure flame cpread for non- -combustible based decks and flame spread and brand penetrat}on for combu~tible ba~ed decks.
Presently available flam~ retardant a~phalt compo~i~ions have had difficulty in qualifyi~y as a Class A material. Many of ~hose that have passed include expensive and ~ometime~ toxic ingredien~s. As such, the compositions ar~ expensive and possibly dangerous.

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Other presently ~vailable 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 reguIati~ns now in force th~roughout the Unit~d States.

SUMMARY OF THE INVENTION

The present invention addresses the current need for an inexpensive flame retardant asphalt composition for roofing materials. The inventive composition includes asphalt, a thermoplastic and a flame retarding ingredient.

Preferably, the composi~ion comprises by weight abou~ 45-65% asphalt, about 1-20% thermopla~tic and about 15-40%

flame retarding ingredient ~"1ame retardan~

Preferably, the flame retardant includes by weight about 60-90% monoammonium phosphate, abou~ 5-30~ ammonium ulfate and about 1-5% methyl hydrogen pslysiloxane. Some inert filler~ may be added to complete the composltion.

~ preferred embodiment o~ the ~lame retardant a~phalt composition has pa~sed the UL 790 test~ for Class A

material~. As such/ that composition complies with many, i no~ most, of the re~ulations for roofing materials now in place in the United 5tates.

The composi~ion is manufactured by mixing th~ asphalt and a thermoplastic at~temperatur~s between about 325-425 ext, the flame retardant is added and mixed into the modified asphalt, preferably by a paddle mixer. ~5 such, the composition i~ easy to make.
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A ma~or ingredient of the flame retardant is ammonium sulfate. Ammonium sulfate is an i~expensive material sometimes used as a fire retardant.

S A second major ingredient of the flame retardant is monoammonium phosphate. Monoammonium phosphate is also an inexpensive flame r~tardant. It is presently less expensive than halogen based flame retardants and up to four times less than polyammonium phosphate of comparable strength.

Monoammonium phosphate is very soluble in water.
Ammonium sulfate i~ rela~ively soluble in water. Both ingredients have a tendency to leach out of compositions lS exposed to water. As such, neither ingredient has been used as a major ingredien~ in a flame retardant asphalt composition.

The flame retardant includes a methyl hydrogen polysiloxane ("silicone polymer") that forms a film. The film is a ~urface treatment that prevents water adsorption and absorption~ As such, the film makes the flame retardant water repellent. The film al~o allows the flame retardant to with~tand higher proces~ing temperatures and W radiation.

The ~eatures and advantages of the present invention are meant to be illustrative rather than exhaustive.
Further advantages and featur~ of the presen~ inven~ion will become apparent while reviewing the detailed d~ cription of the invention.

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DET~I~ED DESCRIPTION OF ~HE INV~NTION

The present invention comprises three ingredients:

(1) bitumen;

~2) a thermoplastic; and (3) a flame retarding agent.
The bitumen ingredient preferably includes petroleum asphalt. Preferably, this ingredien~ compri~es about 45-65% by weight of the composition. It is preferred that the bitumen in~redient be 52% of the composition.
The thermoplastic ingredient may include thermoplastic elastomers or thermoplastic rubbers including crap thermoplastics. More specifically, this ingredient i5 preferably styrene-butadiene-styrene (SBS).
The thermoplastic i5 blended wi~h the bitumen at temperatures between 325~ and 42S ~.

Preerably, the 1ame retardant comprise~ between about 15-40% o~ the composition. The ingredientq of the flam~ ~etardant include, preferably, about 60-90~
monoammonium phosphate, about 5~30% ammonium ~ulfate and about 1-5~ methyl hydrogen polysiloxane. The Flame retardant is mixed into the thermoplastic modified bi~umen. Preferably, the bitumen i~ maintained at 325-425 F durin~ mixing.

The mos~ preferred flame retardant i~ 35~ wt of ~hecompo~ltion and comprise~:

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(1~ about 75~ monoammonium ~hosphate;
~--. . , (2) about 10% ammonium sulfate;

~3) about 1% methyl hydrogen polysiloxane;

(4) about 5% mu~covite mica;

(5) about 5% magnesium aluminum ~ilicate.
Such a retardant is available from An~ul Fire Protection, Inc. under the trade name FORAY. Ansul Fire Protection, Inc. is located in Marinette, Wisconsin.

The inventive composition i5 conveniently made by first blending the thermoplastic with the asphalt at temperatures between 325 and 425~ ~. Next, the flame retardant is added to the thermoplastic modified asphalt by mixing, pre~erably by paddle mixers where the modified ~sphalt i8 maintained above 325 ~.

The inventive composition may be used in several diff~rent roofing application~ and on dif~erent carrier~.
The compo~it1on may be u~ed in conjunction with polyester or ~ib~rgl~ reinforc~ment~.

The following example is presented to how a pre~rr~d embodim~nt of the invention. It is not intended to limit the ~cope or content of the disclosure or invention.

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2~2~2~3 ~he preferred composition includes by weight:

(1) about 52% asphalt;

(2) about 13~ styrene-butadiene-styrene;

(3) about 26% monoammonium phosphate;

(4) about 1% methyl hydrogen poly~iloxane;
(5) about 4~ ammonium sulfate;

(6) about 2%.muscovite mica; and (7~ abou~ 2~ magnesium aluminum silica~e.

This composition has been tested by UL under UL 790 conditions. UL has awarded ~he preferred composition a Class A ranking.
~ he preferred composition may be made by:

tl) ~eatin~ the a.sphalt to about 350~400 ~.;

(2) Adding and mixing ~tyrene-butadiene-styrene ~"SBS") into the heated asphalt; and (3) Adding and mixing the flam retardant into the heated modified bitumen with a paddle mixer.
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The example and description~ provided are meant to be a clear indication of the inventive composition. ~owever, rea~onable modlfications and variation~ are po~sible without departing ~rom the spirit or ~cope of the invention.

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Claims (3)

1. A composition comprising:

(a) asphalt;

(b) a thermoplastic;

(c) monoammonium phosphate;

(d) ammonium sulfate; and (e) silicone polymer.

2. A flame retardant composition comprising:

(a) about 45-65% wt asphalt;

(b) about 1-20% wt styrene-butadiene-styrene;

(c) about 15-40% wt flame retardant;

(d) the flame retardant comprises:

(i) about 60-90% wt monoammonium phosphate, (ii) about 5-30% wt ammonium sulfate:

(iii) about 1-5% wt methyl hydrogen polysiloxane.

3. A flame retardant asphalt composition comprising about:

(a) 52% wt bitumen;

(b) 13% wt styrene-butadiene-styrene;

(c) 35% wt flame retardant where the flame retardant comprises about:

(i) 75% wt monoammonium phosphate, (ii) 10% wt ammonium sulfate, (iii) 1% wt methyl hydrogen polysiloxane;

(iv) 4% wt muscovite mica; and (v) 4% wt magnesium silicate.