EP0236492A1

EP0236492A1 - Flame and heat transfer retardant mixture

Info

Publication number: EP0236492A1
Application number: EP19860906114
Authority: EP
Inventors: Lawrence H. Sadler
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-09-19
Filing date: 1986-09-18
Publication date: 1987-09-16
Also published as: AU6403786A; WO1987001718A1

Abstract

Matériau ralentissant la propagation du feu, des flammes et de la chaleur, composé d'un mélange de substances chimiques comprenant du sulfate d'ammonium, du borax, du diméthyle sulfoxyde et un agent d'activation/conditionnement sélectionné dans le groupe comprenant l'acide borique, l'oxyde de zinc et les sels de Clayber. Le mélange résultant est une poudre essentiellement sèche pouvant se combiner avec des véhicules tels que de l'eau, de la peinture ou de la colle pour être appliquée sur différentes surfaces. Ce matériau est destiné à être utilisé dans une vaste gamme d'applications, parmi les plus importantes le traitement d'articles peints inflammables de toits de bardeaux, d'isolations et d'éléments métalliques structuraux, et la création de zones coupe-feu en dispersant le matériau sur le cheminement des incendies éventuels. Le matériau est non toxique et peut être utilisé dans de nombreux cas où il est désirable d'empêcher ou de limiter la propagation des flammes et le transfert de chaleur.Material slowing the spread of fire, flame and heat, consisting of a mixture of chemicals including ammonium sulfate, borax, dimethyl sulfoxide and an activating / conditioning agent selected from the group consisting of boric acid, zinc oxide and Clayber salts. The resulting mixture is an essentially dry powder that can be combined with vehicles such as water, paint or glue to be applied to different surfaces. This material is intended to be used in a wide range of applications, among the most important being the treatment of flammable painted articles of shingle roofs, insulation and structural metal elements, and the creation of fire-resistant zones in dispersing the material on the path of any fires. The material is non-toxic and can be used in many cases where it is desirable to prevent or limit the spread of flame and the transfer of heat.

Description

FLAME AND HEAT TRANSFER RETARDANT MIXTURE

TECHNICAL _______

The present invention relates generally to fire and flame retardant and heat transfer retardant materials and more specifically to mixtures utilized for application to flammable materials to prevent ignition and flash or the spread of flames or conductive transfer of heat. Predominant expected uses of the current invention are in protecting building materials and for use in stopping the spread of conflagrations.

BACKGROUND ___

It has long been desirable to provide methods of treating various useful materials in order to prevent them from being unduly flammable. This is desirable in order to prevent immediate ignition of materials upon the application of heat and also to prevent the spread of fire if it does become started in the vicinity of the treated material. This sort of treatment is particularly important in materials utilized in structural elements of housing and business buildings and also in furniture.

Another area in which flame retardant materials are particularly valuable is in the fighting of fires, such as forest and brush fires. Any and all methods which can possibly be utilized are desirable to stop the spread of forest fires and

■ brush fires. Flame retardants are of value if they can be placed on as yet unburned materials before the onset of the fires.

Various methods are used to fight fires. In" order for a flame or fire to be sustained, three components are required. These are heat, oxygen and fuel, namely a flammable material. Conventional fire fighting techniques ordinarily attack flames from the standpoint of dampening the heat factor or supressing the supply of oxygen. However, most flame retarders, including the present invention, primarily operate to remove the fuel component. This is accomplished by making otherwise flammable materials nonflammable. The ordinary mechanism is to treat the materials with an inhibiting compound, mixture or suspension which blocks the usability of the flammable material as a fuel. Numerous mixtures, compounds and suspensions have been developed for the purpose of retarding flames. These materials are ordinarily placed on the flammable component in some manner which allows them to remain associated with that component over an extended period of time. Some of the most common techniques are various methods of treating insulating material, shingles, paints and lubricating materials. Various mixtures and formulations of materials have been utilized over the years, depending upon the specific requirements of the application.

Some of these prior art efforts to achieve flame retardants ar& described in various U. S. Patents. These include: No. 4,5:14,327, issued to _L__ _Q.Q._.J No. 4,468,495, issued to ___ Pearson; No.4,168,175, issued to __. _J_t___; No.4,184,969, issued to __. ______£.; and No. 4,419,401, issued to <__ Pearson. All involve the formulation of agents designed to inhibit flame in otherwise flammable materials.

Some specialized applications of the mixtures such as those of the present invention, relate to inhibition of heat transfer as a more important characteristic. This type of characteristic is important particularly in the structural building industry wherein it is desirable to coat the steel structural girders to prevent the conductive transfer of heat from one hot spot to other areas throughout the building, and thus inhibit ignition in the other areas. In this situation, the active material fights fire by removing or preventing the transfer of the heat element, rather than attacking the fuel, since the steel girders are not flammable in any case.

Various compositions and mixtures have been developed for this purpose, as well. However, most of these are maintained as trade secrets in the construction industry, and the precise formulations are unknown.

Of course, improvements in all of these areas are always desirable. None of the prior art techniques completely cover all of the main fire retardant and heat transfer retardant capabilities. The prior art methods and materials suffer from one or more of the following problems: toxicity, limiting their usage to certain materials; difficulty in mixing^' with common carriers and suspending media; high cost of manufacture; undesirable byproducts; insufficient flame retardant and/or heat transfer retardant capabilities; and difficulties in application or use. DISCLOSURE Q£ INVENTION

Accordingly, it is an object of the present invention to provide a mixture which is usable both as a flame and fire retardant material and as a heat transfer retardant material.

It is another object of the present invention to provide a flame retardant material which is nontoxic to humans and animals and does not harm most living plants when directly applied.

It is another object of the present invention to provide a fire retardant material which has dramatically improved performance characteristics over those of the prior art. It is a further object of the present invention to provide a heat transfer retardant material having excellent heat transfer retarding characteristics at a low cost.

It is yet another object of the present invention to provide a combined flame retardant and/or heat transfer retardant material which is easily manufactured.

The present invention is a mixture which, depending on the substitution of one element, may be utilized effectively either as a fire and flame retardant material for application to any of an extremely wide variety of flammable components, or as a heat transfer retardant material for application to metallic items. The primary expected uses of the invention are in the areas of treating building materials such as shingles, insulation, paints for use on walls, stucco, furniture, carpeting and the like; for use as a fire break as in treating an area of unburned forest and/or brush during a fire fighting operation; and. for use as a treatment to steel girders or other high heat transfer materials to prevent the spread of a conflagration by conductive heat transfer.

Briefly, a preferred embodiment of the present invention is a flame and heat transfer retardant mixture including ammonium sulfate, borax, dimethyl sulfoxide and a conditioning agent selected from the group including boric acid and zinc oxide. If the mixture is to be utilized in an application where it is to be suspended in a liquid or applied to nonmetallic components, then the boric acid is utilized. If, on the other hand, the mixture is to be applied to metallic components such as steel, to which the boric acid is a caustic agent, then the zinc oxide is utilized. Various -suspending materials and formulations of mixing instructions are applicable depending on the precise usage desired.

An advantage of the present invention is that it penetrates the surface of porous materials extremely effectively, and thus provides a thicker and more effective resulting layer of flame retarder material than prior art efforts.

Another advantage of the present invention is that it is nontoxic to the great majority of absorbent materials and to living things such as plants and animals, and contains no components which are known to be harmful to humans in the envisioned usages.

A further advantage of the present invention is that it produces superior flame retardant and heat transfer retardant results while being easy to manufacture.

Still another advantage of the present invention is that it mixes easily in common solvents and suspending media such as water and paint.

Yet another advantage of the present invention is that it may be combined with glue to form a flux for ready treatment of steel and other metallic elements.

A still further advantage of the present invention is that it does not degrade the surfaces to which it is applied.

Another advantage of the present invention is that it has excellent permanence characteristics on exterior building materials, such as shingles.

The uses and other objects and advantages of the present invention will become clear to those skilled in the art, in light of the description of the best presently known mode of carrying out the invention and of the industrial applicability of the preferred embodiments, which follow. BEEΣ. EΩΩR QΣ. CARRYING Ωttt INVENTION This invention is a fire and flame retardant/heat transfer retardant mixture adapted for usage in a variety of situations wherein it is desirable to lower or eliminate a flammable material's susceptibility to flame or to reduce a heat conductive material's tendency to conduct exteriorally applied heat. The mixture is easily formulated and is slightly modified for different applications depending on the selected object material and the type of use.

The preferred emodiment of the mixture includes a formulation of 'materials wherein the primary components are ammonium sulfate 0₇. 10H₂0], commonly known as borax; dimethyl sulfoxide ("DMSO")

[C_H_SO], also known as methylsulf oxide; and a conditioning agent

3 6 selected from the group including boric acid [H-B0-, zinc oxide ZnO, and Clayber salts]. The formulation is created as an essentially dry powder which is adaptable for solution, dispersal or suspension in a wide selection of media for application to a variety of materials.

A first preferred embodiment of the mixture of the present invention, referred to herein as Formulation 1, is suitable for use in solution with water or dispersal or suspension in other solvents and includes the primary ingredients in the weight and molar ratios set forth in Table 1 and described below.

The weight ratios of the ingredients are as follows.

TABLE 1

Ingredient Weight Ratio % by Weight Mole. R__i_i-_. ' Ammonium Sulfate 2.5 13.5% 1.71

Borax 6.0 32.4% 1.42

DMSO 1.0 5.4% 1.00

Boric Acid (ortho) 9.0 48.7% 13.1

Ammonium sulfate is provided in a ratio of 2.5, the sodium tetra borate decahydrate (borax) has a ratio of 6.0, dimethyl sulfoxide (DMSO) is the ratio determining agent and is assigned 1.0, while the boric acid has a ratio of 9.0. At normal mixing temperatures, only the DMSO is in liquid form, the rest being crystals, ground into powder. The dry materials are ground finely prior to mixing and are then thoroughly mixed such that a sampling from any portion of the resulting mixture will yield the same material ratios. Clayber salts may be substituted for boric acid at the same weight ratio.

Although it is believed that the DMSO creates a loose bond for the mixture such that all of the components are maintained in close relationship on a physical level, the inventor is aware of no. evidence that any chemical changes actually take place in the materials during the mixing process. The result is a substantially dry powder, being wet somewhat by the dimethyl sulfoxide, but not being in the form of a solution.

For many common usages, such as the treatment of porous flammable materials with the mixture, it is desirable to dissolve the mixture in water in order to provide for easy transfer onto the porous material. The preferred method is to slowly add the mixture to water with the quantity of water being selected such that it has a weight ratio to the DMSO of about 50 to 1. Ordinary mixing techniques are sufficient to cause the mixture to go into solution or suspension at this ratio.

The resulting solution is appropriate for application to porous materials in such manners as dipping and spraying. It is particularly applicable for use with absorbent materials such as wood, cloth, paper, foam rubber, straw block as used in building materials, fiberglass and cellulose insulation, and other flammable porous materials. The aqueous component of the solution will evaporate subsequent to coating of the item and will leave the fire retardant mixture embedded in the surface of the porous material. Once dried, the material coating is resistant to leaching and/or dissipation. Only when the mixture is applied to living or recently living plants is a noticeable diminishing of effectiveness observable.

The Formulation 1 embodiment of the mixture (shown in Table 1) is also appropriate for mixture with paint. In this instance, the same ratios used for water are utilized with paint substituted for the water (approximately 50 parts point to 1 part DMSO, or 2.7 parts point to 1 part mixture). It has been found that the mixture is especially effective with latex type paints and remains in suspension within the paint throughout application. The mixture is also useful with other types of paint, as well. In this manner, the inventive mixture can be used as a reasonably permanent flame proofing material for painted surfaces.

Since the boric acid component is caustic to steel and other structural metals. Formulation 1 is inappropriate for use with these materials. Therefore, the boric acid is replaced by a different conditioning agent in the material utilized as a heat transfer retardant. For the heat transfer retardant insulating material (Formulation 2), the formula shown in Table 2 is utilized. In this formula, zinc oxide is substituted for the boric acid, the ratios of materials are adjusted, and the ingredients are bound together with glue.

TABLE 2 Ingredient Weight EaiiQ. % by Weight Mole _-___ti__ DMSO l.o 1.06% 1.0

Ammonium Sulfate 10.7 11.3% 7.3 Borax 74.0 78.2% 16.5

Zinc Oxide 2.56 2.7% 2.84 Glue 6.4 6.8% N/A

Formulation 2, shown in table 2, includes dimethyl sulfoxide as the ratio defining agent, having a weight ratio of 1.0. In this formula, ammonium sulfate has a ratio of 10.7, borax has a ratio of 74.0 and zinc oxide has a ratio of 2.56. In order to provide a binder such that the mixture will adhere to the steel girders, the formula also includes a standard binding glue having a ratio of 6.4. Nearly any type of commercially available glue may be utilized. For application to surfaces by a spray technique, it may also be useful to suspend Formulation 2 in water (approximately 30 : 1, water to mixture). This is suitable for use in commercial flux sprayers.

A special situation occurs when it is desired to use the invention to protect powder type insulation material. Although fiberglass and cellulose insulation may be treated by spraying with the aqueous suspension of Formulation 1, this is not sufficient for other insulation materials. One extremely inexpensive and valuable type of insulation material which may be created using the invention uses sawdust as the carrier. This normally flammable material can be rendered into a fireproof insulation by proper addition of the inventive mixture.

A special problem that occurs in using sawdust is that the inventive mixture of Formulation 1, mixed under normal conditions, is a slightly damp material, due to the liquidity of the DMSO. Since sawdust is a very hydrophilic material, it is very difficult to mix the moist mixture of Formulation l.with the sawdust to achieve an even dispersion. This problem can be overcome by carrying out the mixing process of the inventive mixture and of the mixture with the sawdust at temperatures below the melting (crystalization) point of DMSO. The preferred temperature of mixing for the process is approximately 5° C (41° F). The mixture of the present invention is then mixed with sawdust at the same temperature such that the ratio, by weight, of mixture to sawdust is approximately 1 to 100. The resulting flameproof insulation is suitable for use in any circumstance where exposed metal or galvanized metal surfaces will not be contacted by the insulation.

In the event that it is desired to utilize an insulation in circumstances where it will physically contact exposed metal or galvanized metal surfaces it has been found that the mixture should be altered to prevent caustic degradation of the metal surfaces. A modification is accomplished by adding an amount of zinc borate (3Zn0.2B₂0₃) to the inventive mixture prior to mixing with the sawdust. The ratio of zinc borate added is the same as the amount of boric acid. It is found that the zinc borate acts to neutralize the caustic effect of the boric acid, particularly on galvanized surfaces.

The chemicals utilized to manufacture the inventive mixture have been found to be adequate even if not at laboratory grade quality. Minor impurities do not appear to have a significant impact on the effectiveness of the fire retardant mixture. This makes it possible to utilize industrial grade chemicals which substantially reduces the cost of manufacture.

For the purposes of mixing using weight ratios, the materials utilized in determining the ratios set forth in Table 1 and Table 2 had the specific gravity values set forth in Table 3.

TABLE 3

Ingredient Specific Gravity

Ammonium sulfate 1.77

Boric acid 1.4347

Borax 1.73

Zinc oxide 5.61

Zinc borate (powder) 3.64

As is clear from the above, the variety of boric acid utilized is the Ortho crystaline form, also known as boracic acid. Just as the degree' of impurities does not seem to have a significant adverse effect on the inventive mixture, the ratios are not precise. Therefore, although the stated ratios are believed to optimum, substantial variations may occur without degrading the performance. Consequently, extremely careful measurement of the ingredients is not necessary for good results.

Various additional embodiments and utilizations of the above described embodiments are also visualized. For example, suspending the mixture in relluloys oil creates a lubricant which is extremely effective in preventing both heat transfer and ignition of the lubricant in such applications as- lathes and other high friction operations. Various solvents, other than water, may be utilized with the mixture in order to cause the operative mixture suspension to be dispersed within porous material which might be hydrophobic in nature.. The primary ' concern is that the solvent or suspending agent utilized not extract the DMSO, or any other primary ingredient.

Those skilled in the art will readily observe that numerous modifications and alterations of the mixture may be made while retaining the teachings of the present invention. Accordingly, the above disclosure is not intended as limiting. The appended claims are therefore to be interpreted as encompassing the entire spirit and scope of the invention.

5. INDUSTRIAL APPLICABILITY

The present invention is an improved and extremely useful flame and fire retardant mixture which also has excellent heat transfer retardant capabilities. It is adaptable for use in a wide variety of applications wherein it is desirable to inhibit ^' the ignition of materials, the spread of flame or the transfer of heat through nonflammable conducting materials. Known applications are in flame-proofing porous flammable materials and in., heat insulating metal building materials such as steel girders. Other uses which have been observed are in providing temporary flame retardant characteristics to living plants and organic debris, such as in preventing the spread of forest and brush fires, and in creating flameproof and heat transfer retardant lubricants.

The usefulness of the mixture of the present invention as a flame and ignitiant retardant material and as a heat transfer retardant agent is best understood by reference to a number of examples set forth below.

Example J_. A one-half inch thick sheet of untreated plywood was painted utilizing a latex paint having suspended therein the mixture of Formulation 1, as described above. A single coat of paint was applied with the resulting paint having a thickness of 0.63 cm (1/4 in.). A propane torch, set at a high flame level, was- directed at the treated surface of the plywood for an uninterrupted period of two minutes. The temperature rise on the surface of the plywood directly opposite the blow torch innact zone (torch point) was measured and was found to rise 22.2° C (40° F). No flame, other than that created by the torch while burning, was observed. The depth of char on the affected surface was found to be approximately 0.16 cm. (1/16 inch).

E___am£l_e.2. A 1.9 cm. (3/4 in.) steel "H" - beam was coated on one side with the mixture (Formulation 2) to a thickness of contact with a propane torch flame, similar to that of example 1, for a period of three minutes with the torch being centered in a single spot (torch point) for the entire burn period. The temperature rise on the opposing surface of the "H" beam, the untreated surface directly opposite the orch point, was measured. It was found that directly opposite the torch point a heat rise of 2.2° C (4° F) was observed. At a radius of 5 cm.

(2 in.) from the torch point, the measurable temperature rise was

1.4° C (2.5° F). At a radius of 10 cm. (4 in.), the temperature gradient was .6° C (1° F) and at radii of 15 cm. (6 in.) and above no measurable temperature rise was observed.

Example 2.. An ordinary cedar shake shingle having a thickness of 1.9 cm (3/4 cm) was treated in a water solution of the mixture of formulation 1, as described above, by heating the solution to a temperature of (71 C) and immersing the shingle in the solution for a period of 160 seconds. After drying the shingle to complete dryness (2 days), a propane torch flame was centered on a torch point on the shingle for a two minute concentrated burn. No flame was observed and the depth of the resulting scorch on the shingle was 0.04 cm. (1/64 in.). Only areas directly touched by the propane torch showed any degradation.

Example A. A piece of ordinary cotton cloth having a thickness of approximately .15 cm. (0.06 in.) was treated with the aqueous solution of Formulation 1 by spraying the cloth until the cloth was slightly dampened with the solution. The cloth was then allowed to thoroughly dry. When the treated cloth was subjected to the direct propane torch flame for a period of two minutes, there was no flame spread whatsoever, although there was a certain amount of scorch through directly opposite the torch point. Immediately after removing the flame, the temperature of the reverse side of the cloth, as close as possible to the torch point, was measured and it was found that the temperature differential prior to the flame and after the flame was approximately 28° C (50° F).

EL_-_LIC__1_-.5.- A cloth swatch similar to that of example 4, but including synthetics, was treated in the same manner as in example 4. The specific cloth utilized was 70% polyester, 30% cotton.

In this instance, there was a greater degree of scorching and melting-through in the area of the torch point. The temperature increase on the reverse side immediately after a two minute burn was found to be approximately 45° C (80° F).

4E__aini_ls. £• An ordinary commercial cellulose sponge was treated in the same manner as the cloth of example 4. After drying, it was subjected to a one minute direct application of the propane torch flame. It was observed that the sponge tended to-melt and crystalize in the area of direct impact of the torch flame,, but there was no flame and no spread of the melting.

Exam le ϋ. A standard paper towel of commercial quality was treated as the cloth of example 4. When the treated and dryed paper tissue was subject to direct propane torch flame, a substantial amount of scorching was observed, but there was no flame. It was impossible to cause the treated area of the towel to ignite.

As the above examples make clear, there is a substantial potential for widespread commercial utilization of the invention. In addition to the above examples, it has also been observed that the mixture, particularly the aqueous solution of the mixture of Formulation 1, is adequate for application to living plants, such as trees and brush, and may be utilized to create a fire break in applications such as in fighting forest fires. In the case of living: plants, it is found that the usefulness of the mixture will tend to dissipate after a period of a few weeks to a few months,, depending on environmental conditions and the nature of th . plants. However, it is certainly adequate for most of the fire Fighting purposes.

Based on the above advantages and qualities, it is expected that the present invention will have extremely widespread industrial applicability and commercial utilization.

Claims

ua HE QL&IΆS.

1. A flame and heat transfer retardant mixture comprising: ammonium sulfate: sodium tetraborate decahydrate; dimethyl sulfoxide; and an activating agent selected from the group including boric acid, zinc oxide and Clayber salts.

2. The mixture of claim 1 wherein the selected activating agent is boric acid, and the weight ratio of ingredients is optimally: ammonium sulfate 2.5; sodium tetraborate decahydrate 6.0; dimethyl sulfoxide 1.0; and boric acid 9.0.

3. The mixture of claim 2 wherein: the mixture is combined with water to provide a speadable and sprayable liquid for application to flammable materials.

4. The mixture of claim 2 wherein: the mixture is added to water such that weight ratio of water to dimethyl sulfoxide is approximately 50 to 1.

5. The mixture of claim 2 wherein: the mixture is suspended in paint for application to paintable surfaces.

6. The mixture of claim 1 wherein: the mixture is then combined with sawdust to form flowable insulation material.

7. The mixture of claim 6 wherein: the combining of the mixture with said sawdust is accomplished at temperatures below the crystallization point of dimethyl sulfoxide.

8. The mixture of claim 6 wherein the mixture further includes: boric acid as the activating agent; and zinc borate, in an amount equal by weight to the amount of boric acid.

9. The mixture of claim 1 wherein: the mixture is maintained as a flowable solid for dispersal in other flowable solids by combining at temperatures below the crystallization point of dimethyl sulfoxide.

10. The mixture of claim 1 wherein: zinc oxide is selected as the activating agent; glue is added as a bonding agent; and the weight ratio of ingredients is optimally; dimethyl sulfoxide 1.0; ammonium sulfate 10.7; sodium tetraborate decaydrate 74.0; zinc oxide 2.56;and glue 6.4.

11. The mixture of claim 10 wherein the mixture is combined with water for spraying or spreading onto metal structural members and building materials.

12. A fire retardant material formulated by mixing ammonium sulfate, borax, boric acid and dimethyl sulfoxide.

13. The material of claim 12 wherein the optimal weight ratios of ingredients is as follows: amoniu sulfate 2.5; borax 6.0; dimethyl sulfoxide 1.0; and boric acid 9.0;

14. The material of claim 13 wherein: The material is combined into an aqueous medium with a weight ratio of material to medium of between 1:10 and 1:00.

15. The suspension of claim 14 wherein: the ratio is 1:50.

16. A heat transfer retardant material formulated by mixing dimethyl sufoxide, ammonium sulfate, borax and zinc oxide.

17. The material of claim 16 and further including: a binding agent in the form of an adhesive.

18. The material of claim 17 wherein the optimal weight ratios of ingredients are as follows: dimethyl sulfoxide 1.0; ammonium sulfate 10.7; borax 74.0; zinc oxide 2.56;and adhesive 6.4.

19. The material of claim 18 wherein the material is combined into an aqueous medium for spraying or spreading.