Gas-producing material

Abstract

The present invention relates to gas-producing materials, methods of forming gas-producing materials, and uses of gas-producing materials. The gas-producing materials comprise a comminuted foamed polymer, a nitrogen-containing fuel and an oxidiser. The gas-producing materials may be used to suppress a fire.

Claims

1. A method of forming a gas-producing material, the method comprising comminuting a foamed polymer to form a comminuted foamed polymer and combining the comminuted foamed polymer with water, a nitrogen-containing fuel, and an oxidiser to form a paste.

2. The method of claim 1, wherein the foamed polymer is selected from at least one member of a group consisting of phenolic resin foams, polystyrene foams, polyurethane foams, polyethylene foams, polyvinylchloride foams, polyvinylacetate foams, polyester foams polyether foams, and foam rubber.

3. The method of claim 1, wherein the foamed polymer has an average cell diameter of from 0.5 to 5 mm.

4. The method of claim 1, wherein the foamed polymer is open-cell.

5. The method of claim 1, wherein the comminuted foamed polymer has an average particle size in the range from of 1 to 200 μm.

6. The method of claim 1, wherein the method further comprises forming the foamed polymer by a curing reaction between: (a) a liquid resole; and (b) an acid hardener for the resole.

7. The method of claim 6, wherein an insoluble particulate solid is present in the curing reaction in an amount of at least 5% by weight of the liquid resole.

8. The method of claim 6, wherein the method further comprises forming the resole by condensation of at least one phenolic compound with at least one aldehyde.

9. The method of claim 6, wherein the acid hardener is p-toluene sulfonic acid.

10. The method of claim 1, wherein the nitrogen-containing fuel is selected from at least one member of a group consisting of guanidine salts, triazoles and tetrazole, and azo-compounds.

11. The method of claim 1, wherein the nitrogen-containing fuel is in the form of particles with an average particle size in the range of from 5 to 150 μm.

12. The method of claim 1, wherein the oxidiser is selected from at least one member of a group consisting of alkali metal nitrates, perchlorates, and carbonates.

13. The method of claim 1, wherein the oxidiser is in the form of particles with an average particle size in the range of from 1 to 100 μm.

14. The method of claim 1, wherein the method comprises combining: the comminuted foamed polymer in an amount of 8 to 20%; the nitrogen-containing fuel in an amount of 19 to 29%; and the oxidiser in an amount of 55 to 69%, by total weight of the comminuted foamed polymer, the nitrogen-containing fuel, and the oxidiser.

15. The method of claim 1, wherein water is added in an amount of 1 to 100% by total weight of the comminuted foamed polymer, the nitrogen-containing fuel, and the oxidiser.

16. The method of claim 1, wherein the method comprises combining water with the comminuted foamed polymer and subsequently combining the water and the comminuted foamed polymer with the nitrogen-containing fuel and the oxidiser.

17. The method of claim 1, wherein the method comprises drying the paste.

18. The method of claim 17, wherein the method includes drying the paste to contain water in an amount of from 1 to 40% by total weight of the comminuted foamed polymer, the nitrogen-containing fuel, and the oxidiser.

19. The method of claim 17, wherein the drying is carried out at a temperature of from 25 to 110° C.

20. The method of claim 1, wherein the method comprises introducing further components into the gas-producing material, the further components being selected from at least one member of a group consisting of binders, burn rate modifiers, flame inhibition chemicals and additional oxidizing agents.

21. The method of claim 20, wherein the further components in total are present in the gas-producing material in an amount of up to 50% by total weight of the comminuted foamed polymer, the nitrogen-containing fuel, and the oxidiser.

Description

EXAMPLES

(1) A series of measurements on the reaction smoke generated from three types of gas-producing material were conducted.

(2) The three types of gas-producing material were: A. “Prior Art Material with catalyst” comprising potassium nitrate, phenol-formaldehyde resin, toluenesulfonic acid, dicyandiamide B. “Prior Art Material without catalyst” comprising Potassium Nitrate, phenol-formaldehyde resin, dicyandiamide C. “Inventive Material” comprising: potassium nitrate, dicyandiamide, comminuted foamed phenol-formaldehyde resin

(3) The prior art materials are marketed by Villanova and sold as part of a product known as ‘Firestryker’. The “Prior Art Material with catalyst” comprises, by total weight of the composition, potassium nitrate in an amount of 60%, phenol-formaldehyde resin in an amount of 13.73%, toluenesulfonic acid in an amount of 1.29%, dicyandiamide in an amount of 23.46% and water in an amount of 0.86%.

(4) The evaluation of the reaction smoke generated from the three types of gas-producing material was carried out for a period of two hours inside a closed cabin of a volume of 7.7 m.sup.3. For the “Prior Art Material without catalyst”, three charges, each weighing 50 kg, were combusted over a period of two hours. The charges were ignited at intervals of 40 minutes, i.e. the first charge was ignited at the beginning of the two hour period, the second charge 40 minutes into the period, and the third charge an hour and twenty minutes into the period. For the “Prior Art Material with catalyst” and the “Inventive Material”, four charges, each weighing 50 kg, were combusted over two hours. The charges were ignited at intervals of 30 minutes, i.e. the first charge was ignited at the beginning of the two hour period, the second charge 30 minutes into the period, the third charge an hour into the period, and the final charge an hour and a half into the period.

(5) Measurement probes were located inside a small hole inside the cabin.

(6) Measurements were taken on the following pollutants: Combustion gas: CO, NO.sub.x, SO.sub.x (like SO.sub.2), O.sub.2 Phenol Formaldehyde Ammonia Total cyanide (Hydrogen cyanide and salt) Hydrogen sulfide Polynuclear aromatic hydrocarbons
Analytic Methods

(7) Measurements relating to the combustion gas pollutants were carried out for a period of 20 minutes after combustion of the first charge. All other measurements were carried out for the duration of the two hour period.

(8) Combustion Gas: CO, NO.sub.x, SO.sub.x (Like SO.sub.2), O.sub.2

(9) The combustion parameters were measured continuously. A portable meter HORIBA with NDIR detection system was used for measuring CO and SO.sub.2, chemiluminescence was used for measuring NO.sub.x, and paramagnetism was used for measuring O.sub.2

(10) Total cyanide (hydrogen cyanide and salt)—UV-VIS—Inner Method (Rif. Met. Uff. MU 2251:2008+ISO 6703-2:1984)

(11) Hydrogen cyanide measurements were conducted using NaOH water solutions as measuring supports. The NaOH solutions were contacted with pyridine and barbituric acid, and then analysed using US-VIS spectrophotometry at a wavelength of 578 nm.

(12) Phenol—GC-MS—Met. Uff. NIOSH 2546 1994

(13) Phenol measurements were conducted using XAD-7 solid sorbent tubes as measuring supports. The solid sorbent tubes were eluted with methanol. Analysis was carried out using a gas chromatography mass detection system.

(14) Formaldehyde—HPLC-UV—Met. Uff. NIOSH 2016 1998

(15) Formaldehyde measurements were conducted using cartridges containing silica gel coated with 2,4-dinitrophenylhydrazine as measurement supports. The cartridges were eluted with a solution of acetonitrile for HPLC. Analysis was carried out using liquid chromatography at high pressure (HPLC-UV) with a UV-VIS detecting system.

(16) Polynuclear aromatic hydrocarbons—GC-MS—Met. Uff. NIOSH 5515 1994

(17) Measurements were conducted using XAD-2 vials in series with glass fiber filters as measurement supports. The filters and vials were eluted in a hexane-acetone mixture. The obtained solutions were analyzed using a gas chromatography mass detection system.

(18) Ammonia—UV-VIS—Met. Uff. NIOSH 6015 1994

(19) Ammonia measurements were conducted using solid sorbent tubes with silica gel activated with sulfuric acid as measurement supports. The supports were eluted with a solution of ultrapure water. The obtained solutions were analyzed with UV-VIS spectrophotometry.

(20) Hydrogen sulfide—IC—Met. Uff. NIOSH 6013 1994

(21) Hydrogen sulfide measurements were conducted using solid sorbent tubes with coconut shells as measurement supports. The solid sorbent tube were eluted with a solution of NaOH. The obtained solution was analyzed using ionic chromatography.

(22) A glass fiber filter was used for the measurements that require the use of a solid sorbent tube, so as to avoid the packing of the absorbent layer by particulate matter produced during combustion. The filter was also analysed.

(23) Results

(24) Combustion gas: CO, NO.sub.x, SO.sub.x (like SO.sub.2), O.sub.2:

(25) The measurements do not show any important differences between the combustion gases omitted by gas-producing materials. The combustion gases were produced in similar amounts by each material, except for NOx and CO which were produced in slightly slower amounts by the “Prior Art Material with catalyst”.

(26) TABLE-US-00001 Sample 12SP0234-002 12SP0234-023 12SP0234-034 Typology Prior Art Prior Art Material Material Inventive without catalyst with catalyst Material Emission Date Feb. 17, 2012 Feb. 17, 2012 Feb. 17, 2012 Parameter U.M. Value Value Value CO mg/m3 100.5 86.9 108.3 NOx mg/m3 29.4 26.3 29.11 (come NO2) O2 % 20.8 20.8 20.8 SO2 mg/m3 7.5 8.1 9.2
Phenol:

(27) The “Prior Art Material without catalyst” produced less phenol on combustion than the other materials. The absence of a toluenesulfonic acid catalyst used for crosslinking of the phenol-formaldehyde resin during preparation of the “Prior Art Material without catalyst” meant that cross-linking was carried out for a longer time, thereby allowing unreacted phenol to disperse into the atmosphere. Thus, there is less phenol to be released on combustion of the “Prior Art Material without catalyst”. As the resin in the “Inventive Material” is pre-foamed, the phenol has had some time to disperse from the foam into the atmosphere. Thus, the resin can be considered “old” in comparison to the resin used in the “Prior Art Material with catalyst”.

(28) TABLE-US-00002 Sample 12SP0234-002 12SP0234-023 12SP0234-034 Typology Prior Art Material Prior Art Material Inventive without catalyst with catalyst Material Emission Date Feb. 15, 2012 Feb. 21, 2012 Feb. 21, 2012 Parameter U.M. Value Value Value Phenol mg/m3 0.066 31 4.8
Formaldehyde:

(29) The formaldehyde values are low in each of the gas-producing materials.

(30) TABLE-US-00003 Sample 12SP0234- 12SP0234-006 12SP0234-024 035 Typology Prior Art Prior Art Material Material Inventive without catalyst with catalyst Material Emission Date Feb. 15, 2012 Feb. 21, 2012 Feb. 21, 2012 Parameter U.M. Value Value Value Formaldehyde mg/m3 <0.006 <0.006 <0.006
Ammonia:

(31) The ammonia values are similar in the three types of material, taking into account the quantities of charges used for the test and the nature of the analyses.

(32) TABLE-US-00004 Sample 12SP0234- 12SP0234-003 12SP0234-021 019 Typology Prior Art Material Prior Art Material Inventive without catalyst with catalyst Material Emission Date Feb. 15, 2012 Feb. 21, 2012 Feb. 21, 2012 Parameter U.M. Value Value Value Ammonia mg/m3 0.5173 1.03 1.77
Polynuclear Aromatic Hydrocarbons:

(33) The results show that polynuclear aromatic hydrocarbons are produced from organic components in the materials during combustion. The “Inventive Material” generated, on average, smaller quantities of polynuclear aromatic hydrocarbons compared to the other two materials. Without wishing to be bound by any theory, it is believed that the smaller quantities measured could be as a result of the higher combustion temperature of the “Inventive Material” causing greater decomposition of the polynuclear aromatic hydrocarbons.

(34) TABLE-US-00005 Sample 12SP0234-004 12SP0234-021 12SP0234-031 Typology Prior Art Material Prior Art Material Inventive without catalyst with catalyst Material Emission Date Feb. 15, 2012 Feb. 21, 2012 Feb. 21, 2012 Parameter U.M. Value Value Value Naphthalene Ng/m3 786 16861 10180 Acenaphthylene Ng/m3 1099 6789 5837 Acenaphthene Ng/m3 292 58.3 257 Fluorene Ng/m3 484 1669 790 Phenanthrene Ng/m3 4054 14169 4940 Anthracene Ng/m3 877 2494 820 Fluoranthene Ng/m3 1434 3269 1150 Pyrene Ng/m3 614 1267 533 Benzo(a)anthracene Ng/m3 801 1744 340 Chrysene Ng/m3 1386 2633 417 Benzo(b)fluoranthene Ng/m3 451 764 185 Benzo(k)fluoranthene Ng/m3 437 569 207 Benzo(a)pyrene Ng/m3 412 1392 453 Benzo(e)pyerne Ng/m3 376 828 263 Perylene Ng/m3 43.3 103 23.3 Indeno(1,2,3-cd)pyrene Ng/m3 94.4 133 33.3 Dibenz(a,h)anthracene Ng/m3 141 211 36.7 Benzo(g,h,i)perylene Ng/m3 274 408 61.7 Dibenz(a,l)pyrene Ng/m3 83.3 283 40 Dibenz(a,e)pyrene Ng/m3 82.2 161 25.3 Dibenz(a,i)pyrene Ng/m3 45 150 20.7 Dibenz(a.i)pyrene Ng/m3 25.6 72.2 18
Hydrogen Sulphide:

(35) The “Prior Art Material without catalyst” produced a minor amount of hydrogen sulfide (H.sub.2S), very likely due to the absence of toluenesulfonic acid used as a catalyst. The “Inventive Material” produced more hydrogen sulphide than the “Prior Art Material with catalyst”. This is somewhat expected from given the relative amounts of sulphur present in the mixtures before combustion, shown below along with the amounts of certain other components.

(36) TABLE-US-00006 Sample 12SP0234- 12SP0234-005 12SP0234-020 030 Typology Prior Art Prior Art Material Material Inventive without catalyst with catalyst Material Emission Date Feb. 15, 2012 Feb. 21, 2012 Feb. 21, 2012 Parameter U.M. Value Value Value Hydrogen mg/m3 0.394 1.096 1.841 sulfide (H2S)

(37) TABLE-US-00007 Sample 12SP0234-016 12SP0234-017 12SP0234-018 Typology Prior Art Material Prior Art Material Inventive without catalyst with catalyst Material Emission Date Feb. 21, 2012 Feb. 21, 2012 Feb. 21, 2012 Parameter U.M. Limit Value Value Value Total Bromine % — <0.01 <0.01 <0.01 Total Chlorine % — 0.09 0.16 0.11 Total Fluorine % — 0.01 0.02 0.02 Total Iodine % — <0.01 <0.01 <0.01 Total Sulphur % — 0.02 0.1 0.35
Total Cyanide (Hydrogen Cyanide and Salt):

(38) A large difference can be seen between the cyanide produced on combustion of the “Inventive Material” and the prior art materials. The “Inventive Material” emits an amount of cyanide that is over ten times smaller than that emitted by the prior art materials, thereby allowing a much greater amount of gas-producing material to be used per unit of confined space. Without wishing to be bound by any theory, it is believed that small value observed in connection with the “Inventive Material” could be attributable to a higher temperature of combustion i.e. over 1000° C. versus less than 800° C.

(39) TABLE-US-00008 Sample 12SP0234- 12SP0234-007 12SP0234-019 019 Typology Prior Art Prior Art Material Material Inventive without catalyst with catalyst Material Emission Date Feb. 15, 2012 Feb. 21, 2012 Feb. 21, 2012 Parameter U.M. Value Value Value Total Cyanide mg/m3 76.7 48.4 3.16 (HCN and Salt)

(40) As can be seen from the experimental evidence, the gas-producing materials are suitable for suppressing fire, particularly in confined spaces where the potential accumulation of unwanted by-products can be harmful to humans. The results also show that the use of a comminuted foamed polymer leads to a reduction in cyanide emissions from a gas-producing material comprising a nitrogen-containing fuel and an oxidiser.