GB1595892A - Fire protective insulating product - Google Patents

Description

(54) FIRE PROTECTIVE INSULATING PRODUCT (71) We, THE FLAMEMASTER CORPO- RATION, a Corporation organized according to the laws of the State of Nevada, United States of America, of 11120 Sherman Way, Sun Valley, California, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to fireproofed articles and to a modification of or an improvement in the invention described and claimed in our Patent No. 1 488 132.

The need for a means of fireproofing electrical conductors, conduits or pipes so they will withstand high temperature fires for extended periods of time has become apparent in many industries. One industry where such high temperature protection is sought is the petroleum industry. Because of the high flammability of products being stored and transported, protection against high temperature petroleum flash fires for extended periods of time is essential. It is necessary that the piping and electrical systems, which may be connected throughout an entire plant, do not ignite and thereby spread the fire throughout the plant. Rather. pipes and cables must be made to withstand high temperature fires for periods of 15 minutes or more so that the fire may be contained to maintain the system functional when fire occurs to permit an orderly shutdown to isolate the system and/or to extinguish the fire with minimum damage to the system.

Typical non-flammable plastics cable insulation such as polyvinyl chloride, neoprene or chlorinated polyethylene cannot withstand such high temperature fires for extended periods of time. When such cables are exposed to a fire, the insulation decomposes and the chlorine content is freed and combines with atmospheric moisture or water which has been used for fire extinguishing to form hydrochloric acid, which can penetrate concrete foundations and attack steel reinforcement. However, because ofthe excellent electrical properties, ready availability and low cost of such materials as polyvinyl chloride, it is desirable to use them for electrical insulation and piping.

The electrical wiring system for many industrial plants utilizes a cable tray into which a plurality of cables are placed. Such a tray increases the fire hazard over the alternative system of encasing the cables in metal conduits. In the tray system, the cables are simply laid on suspended trays through the plant, which facilitates installation and repair of the cables since they do not have to be pulled through a conduit as in the alternative method. However, in the tray, the fire hazard is increased because of the number of cables set side by side as well as the combustible debris which may collect in the suspended trays.

Similarly, the piping system in many chemical plants must be geared to handle corrosive and flammable fluids. Because of the corrosion resistant nature of pipes made from plastics materials such as polyvinyl chloride, they have found wide application for the pumping and storing of corrosive fluids. Where such pipes are used in plants such as petroleum refineries or in the chemical industry to transport corrosive fluids, it is essential that they be able to withstand high temperature flash fires at, for example, 1600 to 2000"F.

Simple and efficient means of protecting cables and pipes from high temperature fires for extended periods of time have not been altogether successful. Where the cable or pipe is wrapped or coated and exposed to the harsh environment of a chemical plant or to the outdoor weathering, asbestos wrappings and intumescent coatings have been found to deteriorate and lose their fire protective ability. Glass fibres when used for such applications have generally demonstrated a higher strength and durability over their asbestos counterparts. However, since many glass fibres melt at approximately 1000oF, they are not suitable protection against the high temperature flash fires which may occur in a petroleum refining plant.

Incorporation of high temperature fibres such as asbestos into a durable and weatherresistant coating such as described in U.S.

Patent 3 642 531 has given significant success in protecting against fire propagation. However, at temperatures of approximately 1600 to 2000"F, generally about 2 to 5 minutes is required for the cable to reach a 200"F critical temperature when coated with such an asbestos filled, organic coating. However, to allow adequate time for plant shutdown and isolation of the fire, times of 15 minutes to 20 minutes are desired.

Other schemes proposed for protecting cables for extended periods against high temperature fires have generally called for multiple layers for protection. For example, the prior art has taught a 4-layer coating which includes silicone rubber, glass cloth, and asbestos for the high temperature protection of an insulated conductor.

The present invention provides a fire protective insulating product which comprises a first, non-combustible, fibre glass layer, preferably having a thickness of at least 0.5 inch, and, bonded thereto. a second layer comprising from 3 to 750i by weight of a noncombustible fibrous material and from 5 to 97% by weight of a natural or synthetic resin binder, the second layer having a content of organically bound halogen atoms of more than 205r by weight.

The second layer preferably has a content of organically bound halogen atoms of from 25 to 754 by weight, advantageously from 30 to 70% by weight, the halogen atoms being provided by the resin(s), e.g. polyvinyl chloride or polyvinylidene chloride, or by one or more additives. e.g. a chlorinated hydrocarbon or by both the resin(s) and one or more additives.

The non-combustible fibrous material is preferably present in an amount of from 5 to 30cur by weight, based on the total weight of the second layer and the resin is preferably present in an amount of from 20 to 85 percent, on the same basis.

As will be appreciated from the following di.icusslon. the products of the present invention are capable of protecting articles such as pipes. conduits, cables and cable trays against flames of 1600 to 2000F for period of 15 minutes or more without substantially adding to their thickness. In addition they are easy to manufacture and apply and exhibit good durability and weatherability.

One form of fire protective product in accordance with the present invention will now be described, by way of example only, with reference to the accompanying draw ings, in which: Figure 1 is a fragmentary perspective view of an insulated electrical cable having wrapped thereabout the fire protective product of this invention; Figure 2 is a cross-section view taken on line 2-2 of Figure 1; and Figure 3 is a cross-sectional view of an electrical cable tray having the fire protective product of this invention applied thereabout.

Referring to Figures I and 2, the fire protective product of this invention, comprising an inner or first layer 1 and an outer or second layer 2 is shown wrapped about a conduit 3. The conduit 3 may be electrical insulation such as polyvinyl chloride in which case 4 will be an electrical conductor.

Alternatively, 3 may be a metallic electrical conduit containing an electrical cable or piping such as metallic or rigid polyvinyl chloride pipe through which corrosive or flammable fluids may flow.

Referring to Figure 3, the fire protective product of this invention, having an outer layer 6 and an inner layer 7 is wrapped about a cable tray 8 having a plurality of conductors 9 running through it. For maximum fire protection, the cables individually or collectively, may be wrapped with the fire protective product as well as the tray containing the plurality of such conductors. Also a double wrap of the fire protective product may be utilized to ensure complete coverage of the cable, pipe, or tray. Alternatively, a further wrapping of the material of the outer layer may be employed.

The inner layer of the fire protective product is preferably a flexible fibre glass blanket approximately r to one inch thick.

Such blankets are available, for example, from Pittsburgh Corning Corporation under the designation "Temp-Mat", which is a needled fibrous mat meeting Military Specification MIL-1-16411D. Type 11. To facilitate securing the fire protective product onto the pipe or cable, a pressure sensitive adhesive suitable for use in the manufacture of pressure sensitive tapes may be coated onto one surface of the glass fibre layer. Referring again to Figure 2, the surface to be'adhesive coated is that surface of layer I in contact with conduit 3.

Where specific shapes are to be encased.

the fibre glass layer may take the form of a moulded fibre glass part. Although maximum fire protective properties are obtained when the inner layer is made up entirely of glass. mixing of the glass with a suitable moulding resin to form specific shapes also gives acceptable results.

Coated onto the glass layer I is a fire protective coating 2, for example a water based coating or an organic solvent based coating. The dried coating, which forms the outer layer of the fire retardant product of this invention contains from 3 to 75% by weight, preferably from 5 to 30%, of noncombustible fibres. The provision of asbestos fibres in the dried coating has been found to given excellent high temperature resistance for extended periods. However, other high temperature resistant inorganic fibres such as aluminum-silica refractory fibres, carbon, quartz, or fibrous talc, and high temperature resistant organic fibres such as nylon or phenolic fibres available from E.I. duPont de Nemours & Company under the trade designation "Nomex" (Trade Mark) and from Carborundum Company under the trade designation "Kynol" respectively, may be used in place of or in addition to asbestos.

These fibrous materials are noncombustible in that they do not support combustion and do not lose their fibrous integrity or reinforcing ability when exposed for a period of at least 15 minutes to temperatures of from 1600 to 2000 F.

Since neither glass fibres in the form of a mat or blanket of k to 1" thickness nor the resinous fire protective coating, when used alone, have been found to afford more than about 5 minutes protection against flames of 1600 to 1000"F, it has now been discovered that an unexpected and synergistic result is obtained by combining both layers into one fire protective product in that such high temperature flames may be withstood for periods of 20 minutes and more. Although the reason for this result is not fully understood, it is believed that the outer high temperature fire protective coating sufficiently dissipates the heat from the open flame and effectively minimizes the transfer of heat from the flame to the fibres so that the lower melting glass fibres of the inner layer are not subjected to temperatures sufficiently high to melt the glass until an extended period of time has elapsed. Because of the excellent insulating properties of the glass, the pipe or cable to be protected is accordingly maintained at a temperature below 200'F for an extended period of time. If however, glass insulation itself is used unprotected by an outer covering. it quickly melts in the presence of a high temperature flame, losing much of its heat insulating properties and in 2 minutes or even less the flame can impinge directly upon the inner cable or pipe.

On the other hand, when a fire protecting coating by itself is used, because of the necessity of formulating the coating with resins. plasticizers, and fillers to provide for durability weatherability, and ease of application (even though these materials have excellent self-extinguishing and fire protec tive properties) much of the heat insulating properties are lost. Thus, because of the lack of proper heat insulation, the time required for the inner conductor or pipe to reach a critical temperature where deterioration and melting may occur (which in the case of polyvinyl chloride is about 200"F) is as low as from 2 to 5 minutes.

The high temperature resistant fibres are dispersed in a suitable resinous binder which makes up from 5 to 97%, preferably from 20 to 85%, by weight of the second layer.

Selection of the binder will depend upon the environment to which it is exposed, the flexibility required, e.g. for wrapping, and the method by which it is to be applied.

Either solvent based resins or water based resin emulsions may be used for this purpose.

Where the glass fibre inner layer is coated with the fire protective composition and is then transported to the high fire hazard area for application onto cables or pipes, either solvent or water based resins may be used.

However, where it is desired first to wrap the cable or pipe with the inner glass layer and then to coat with the fire protective coating in order to produce the product of the present invention, the use of non-flammable water based resins for application in high fire hazard areas is desirable. Suitable resins which may be employed include polyvinyl acetate, GRS rubber, chlorinated rubber, natural rubber, methacrylate and acrylate resins, elastomeric polyurethanes, polyvinyl chloride, polyvinylidene chloride, vinyl chloride/vinylidene chloride copolymers, vinyl acetate/vinyl chloride copolymers, vinyl acetate/ethylene copolymers, epoxy resins, polystyrene and acrylonitrile/butadiene/styrene copolymers.

As essential characteristic of the fire protective coating which forms the second layer of the product of the present invention is that it comprises more than 20% by weight of organically bound halogen atoms which help impart flame retardancy or self-extinguishing properties to the coating. This organically bound halogen content may come from the resin binder, e.g. polyvinyl chloride or polyvinylidene chloride, but in many cases, it will be desirable to incorporate a further nonresinous material as a source of halogen.

Examples of such material, which are prefer- ably incorporated in amounts of up to 50% by weight, based on the total weight of the second layer are halogenated hydrocarbons, particularly chlorinated and brominated hy- drocarbons, the chlorinated hydrocarbons being generally preferred because of economic considerations. Examples of such halogenated hydrocarbons include chlorinated paraffin, such as that available from Diamond Shamrock Corporation under the trade name designation "Chlorowax 70" (Registered Trade Mark), which contains from 68 to 73 weight percent chlorine, chlorinated naphthalene, chlorinated terphenyl, mixtures of such materials, hexabromocyclodecane, tribromobenzene, polytetrafluoroethylene, chlorotrifluoroethylene and per chloropentacyclodecane. Other compounds which are suitable sources of organically bound halogen include decabromodiphenyloxide, tetrabromophthalic anhydride, tris(2,3-dibromopropyl)phosphate, trisbetachloroethyl phosphate, and chlorinated biphenyl.

The coating composition will also preferably include a plasticizer to provide the flexibility necessary for the wrapping of pipes and cables. The plasticizer should be compatible with the particular binder system and will usually be present in an amount of from 1.5 to 7.5 weight percent of the second layer.

Typical plasticizers include tris-fl-chloroe- thyl phosphate, a chlorinated biphenyl, butyl benzylphthalate, dibutyl phthalate, triscresyl phosphate, triphenyl phosphate, and cresyl diphenyl phosphate. It will be appreciated that the plasticizer may contribute at least partially to the content of organically bound halogen atoms.

Preferably. the outer fire protective coating also includes an antimony-containing compound such as antimony-trioxide. Generally from 0.5 to 20%, advantageously from 3 to 15%, of antimony-containing compound, preferably about 10%, may be incorporated into the outer layer. In combination with the organic halogen the antimony compound is believed to interfere with the normal combustion process so as to impart fire retardant properties.

In addition to the antimony compound, the outer layer may also contain various other inorganic fillers for colouring, weatherability and fire retardancy. The quantity of such fillers in the dried coating will generally range from 5 to 30%. Such fillers include, for example, hydrated alumina, calcium carbonate, zinc borate, titanium dioxide, vermiculite and asbestine, which is a mixture of talc and asbestos.

The following Examples illustrate the invention. the parts and percentages being by weight unless otherwise stated.

Example I A coating composition is prepared by mixing 88 parts of a 559 solids content aqueous emulsion of polyvinylidene chloride (73.14"r chlorine), 3 parts phenolic fibres, 3 parts of a chlorinated paraffin (50'r, chlorine). 3 parts antimony oxide and 3 parts hydrated alumina. The composition is prepared in a manner similar to that described in Example 1 of Patent 1 488 132.

The coating composition is applied to a inch fibre glass blanket to give a dry film thickness of about "inch. The dry coating comprises approximately 80% polyvinylidene chloride, 5% phenolic fibres, 5% chlorinated paraffin. 5% antimony oxide and 5% hydrated alumina. The calculated organicalls hound halogen content is 64.67 percent.

The two-layer material thus produced may successfully be employed to insulate electrical conduits.

Example 2 A coating composition is prepared in a manner similar to Example 1 but comprising 85.2 parts of a 522'o solids content aqueous polyvinyl chloride (56.73ass chlorine) emulsion, 3 parts of the chlorinated paraffin, 5.9 parts asbestos fibres and 5.9 parts antimony oxide. This is applied to a " fibre glass mat and dries to give a film comprising approximately 75% polyvinyl chloride, 5% chlorinated paraffin, 10% asbestos fibres and 10% antimony oxide. The calculated halogen content is 45.02 per cent.

The two-layer material thus produced may be employed to insulate a cable tray.

Example 3 A coating composition comprising 43.9 parts of a 55% solids content polyvinyl acetate emulsion, 8 parts of a chlorinated paraffin, 26.5 parts of decabromodiphenyl oxide (83.3% bromine), 8 parts asbestos fibres, 5.6 parts antimony oxide and 8 parts hydrated alumina is applied to a fibre glass mat and dries to give a coating comprising 30% polyvinyl acetate, 10% chlorinated paraffin, 33% decabromodiphenyl oxide, 10% asbestos fibres, 7% antimony oxide and 10% hydrated alumina.

The content of organically bound halogen is 32.5 percent.

The two-layer material may be used as in Example 1 or Example 2.

WHAT WE CLAIM IS: 1. A fire protective insulating product which comprises a first, non-combustible, fibre glass layer and, bonded thereto, a second layer comprising from 3 to 75% by weight of a noncombustible fibrous material and from 5 to 97% by weight of a natural or synthetic resin binder, the second layer having a content of organically bound halogen atoms of more than 20neo by weight.

2. A product as claimed in claim 1, wherein the second layer comprises from 20 to 85S by weight of the resin blinder.

3. A product as claimed in claim 1 or claim 2, wherein the resin binder is polyvinyl acetate, GRS rubber, chlorinated rubber, natural rubber, a methacrylate or acrylate resin, an elastomeric polyurethane, polyvinyl chloride, polyvinylidene chloride, a vinyl chloride/vinylidene chloride copolymer, a vinyl chloride/vinyl acetate copolymer, an ethylene/vinyl acetate copolymer, an epoxy resin, polystyrene or an acrylonitrile/butadiene/styrene copolymer.

4. A product as claimed in any one of claims I to 3. wherein the second layer also comprises a non-resinous material contain

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (32)

**WARNING** start of CLMS field may overlap end of DESC **. chloropentacyclodecane. Other compounds which are suitable sources of organically bound halogen include decabromodiphenyloxide, tetrabromophthalic anhydride, tris(2,3-dibromopropyl)phosphate, trisbetachloroethyl phosphate, and chlorinated biphenyl. The coating composition will also preferably include a plasticizer to provide the flexibility necessary for the wrapping of pipes and cables. The plasticizer should be compatible with the particular binder system and will usually be present in an amount of from 1.5 to 7.5 weight percent of the second layer. Typical plasticizers include tris-fl-chloroe- thyl phosphate, a chlorinated biphenyl, butyl benzylphthalate, dibutyl phthalate, triscresyl phosphate, triphenyl phosphate, and cresyl diphenyl phosphate. It will be appreciated that the plasticizer may contribute at least partially to the content of organically bound halogen atoms. Preferably. the outer fire protective coating also includes an antimony-containing compound such as antimony-trioxide. Generally from 0.5 to 20%, advantageously from 3 to 15%, of antimony-containing compound, preferably about 10%, may be incorporated into the outer layer. In combination with the organic halogen the antimony compound is believed to interfere with the normal combustion process so as to impart fire retardant properties. In addition to the antimony compound, the outer layer may also contain various other inorganic fillers for colouring, weatherability and fire retardancy. The quantity of such fillers in the dried coating will generally range from 5 to 30%. Such fillers include, for example, hydrated alumina, calcium carbonate, zinc borate, titanium dioxide, vermiculite and asbestine, which is a mixture of talc and asbestos. The following Examples illustrate the invention. the parts and percentages being by weight unless otherwise stated. Example I A coating composition is prepared by mixing 88 parts of a 559 solids content aqueous emulsion of polyvinylidene chloride (73.14"r chlorine), 3 parts phenolic fibres, 3 parts of a chlorinated paraffin (50'r, chlorine). 3 parts antimony oxide and 3 parts hydrated alumina. The composition is prepared in a manner similar to that described in Example 1 of Patent 1 488 132. The coating composition is applied to a inch fibre glass blanket to give a dry film thickness of about "inch. The dry coating comprises approximately 80% polyvinylidene chloride, 5% phenolic fibres, 5% chlorinated paraffin. 5% antimony oxide and 5% hydrated alumina. The calculated organicalls hound halogen content is 64.67 percent. The two-layer material thus produced may successfully be employed to insulate electrical conduits. Example 2 A coating composition is prepared in a manner similar to Example 1 but comprising 85.2 parts of a 522'o solids content aqueous polyvinyl chloride (56.73ass chlorine) emulsion, 3 parts of the chlorinated paraffin, 5.9 parts asbestos fibres and 5.9 parts antimony oxide. This is applied to a " fibre glass mat and dries to give a film comprising approximately 75% polyvinyl chloride, 5% chlorinated paraffin, 10% asbestos fibres and 10% antimony oxide. The calculated halogen content is 45.02 per cent. The two-layer material thus produced may be employed to insulate a cable tray. Example 3 A coating composition comprising 43.9 parts of a 55% solids content polyvinyl acetate emulsion, 8 parts of a chlorinated paraffin, 26.5 parts of decabromodiphenyl oxide (83.3% bromine), 8 parts asbestos fibres, 5.6 parts antimony oxide and 8 parts hydrated alumina is applied to a fibre glass mat and dries to give a coating comprising 30% polyvinyl acetate, 10% chlorinated paraffin, 33% decabromodiphenyl oxide, 10% asbestos fibres, 7% antimony oxide and 10% hydrated alumina. The content of organically bound halogen is 32.5 percent. The two-layer material may be used as in Example 1 or Example 2. WHAT WE CLAIM IS:

1. A fire protective insulating product which comprises a first, non-combustible, fibre glass layer and, bonded thereto, a second layer comprising from 3 to 75% by weight of a noncombustible fibrous material and from 5 to 97% by weight of a natural or synthetic resin binder, the second layer having a content of organically bound halogen atoms of more than 20neo by weight.

2. A product as claimed in claim 1, wherein the second layer comprises from 20 to 85S by weight of the resin blinder.

3. A product as claimed in claim 1 or claim 2, wherein the resin binder is polyvinyl acetate, GRS rubber, chlorinated rubber, natural rubber, a methacrylate or acrylate resin, an elastomeric polyurethane, polyvinyl chloride, polyvinylidene chloride, a vinyl chloride/vinylidene chloride copolymer, a vinyl chloride/vinyl acetate copolymer, an ethylene/vinyl acetate copolymer, an epoxy resin, polystyrene or an acrylonitrile/butadiene/styrene copolymer.

4. A product as claimed in any one of claims I to 3. wherein the second layer also comprises a non-resinous material contain

ing organically bound halogen.

5. A product as claimed in claim 4, wherein said non-resinous material is a halogenated hydrocarbon.

6. A product as claimed in claim 5, wherein said halogenated hydrocarbon is a chlorinated paraffin.

7. A product as claimed in claim 4, wherein said non-resinous material is decabromodiphenyl oxide, tetrabromophthalic anhydride, tris(2,3-dibromopropyl)phosphate, tris-betachloroethyl phosphate, a chlorinated biphenyl, or a mixture of any two or more of said compounds.

8. A product as claimed in any one of claims 1 to 5, wherein the second layer also comprises from 0.5 to 20% by weight of an antimony compound.

9. A product as claimed in claim 8, wherein the second layer also comprises from 3 to 15% by weight of an antimony compound.

10. A product as claimed in claim 8 or claim 9, wherein the antimony compound is antimony trioxide.

Il. A product as claimed in any one of claims I to 10, wherein the second layer comprises a plasticizer for the resin.

12. A product as claimed in claim 11, wherein the second layer comprises from 1.5 to 7.5% by weight of the plasticizer.

13. A product as claimed in claim 11 or claim 12, wherein the plasticizer is trisbetachloroethyl phosphate, a chlorinated biphenyl, butyl benzyl phthalate, dibutyl phthalate, tricresyl phosphate, triphenyl phosphate, or cresyldiphenyl phosphate.

14. A product as claimed in any one of claims I to 13. wherein the second layer comprises from 5 to 30gig by weight of noncombustible fibrous material.

15. A product as claimed in any one of claims I to 14, wherein the noncombustible fibrous material is inorganic.

16. A product as claimed in claim 15 wherein the non-combustible fibrous material is asbestos.

17. A product as claimed in claim 15, wherein the non-combustible fibrous material is an aluminium-silica refractory fibre, carbon, quartz or fibrous talc.

18. A product as claimed in any one of claims J to 4, wherein the non-combustible fibrous material is organic.

19. A product as claimed in claim 18, wherein the non-combustible fibrous material is nylon or a phenolic fibre.

20. A product as claimed in any one of claims I to 19. wherein the content of organically bound halogen atoms is from 25 to 7ride by weight.

21. A product as claimed in claim 20, wherein the content of organically bound halogen atoms is from 30 to 70% by weight.

22. A product as claimed in any one of claims 1 to 21, wherein the first layer has a thickness of at least 03 incIL

23. A product as claimed in any one of claims 1 to 22, wherein the first layer has a thickness of from 0.5 to 1.0 inch.

24. A product as claimed in any one of claims 1 to 23, wherein the first layer comprises a glass fibre mat or blanket.

25. A product as claimed in any one of claims 1 to 23, wherein the first layer comprises a fibre glass moulded part.

26. A product as claimed in any one of claims 1 to 25, wherein alayer of an adhesive is provided on the surface of the first layer remote from the second layer.

27. A product as claimed in any one of claims 1 to 26, which has been formed by coating a dispersion containing the ingredient of the second layer onto the fibre glass layer and subsequently drying said coating.

28. A product as claimed in claim 27, wherein the coating when dry has a thickness of approximately 1/16 inch.

29. A product as claimed in claim 1, substantially as described in any one of the Examples herein.

30. An article which is covered by a fire protective insulating product as claimed in any one of claims 1 to 29, the first layer being in contact with said article.

31. An article as claimed in claim 30, which is a pipe, a conduit, or cable or a cable tray.

32. An article as claimed in claim 30 or claim 31, which has also been provided with a further coating of the material of the second layer.