CA1066180A - Method of applying fire-retardant coating materials to a substrate having corners or other sharp edges - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Protecting a surface from fire and excessive heat by coating it with (1) a protective composition comprising an intumescent paint and glass fibers and (2) a protective layer comprising a flexible, surface-conformable fabric sheet (e.g., a textile fabric) having sufficient strength and permeability to unite with a paint applied therewith, and, optionally, an overcoating of intumescent paint.

Description

1066~80 BACKGROUND OF THE INVENTION
This invention relates to protecting surfaces, such as steel, wood, plastic, etc., from excessive heat and fire, and, particularly, to improving the fire-retardant ànd heat-~èsigtànt p~perties of p~ect~v~ e~tl~gg lhclud=
ing an intumescent paint.
It has previously been found that intumesce~t paints provide particularly effective fire-retardant and heat-resistant surface coatings. These intumescent paints usually contain a film-forming material, a carbonaceous material and a spumific agent and, upon exposure to elevated temperatures, puf~ up to protect the coated substrate. Improved fire-retardant and heat-resistant protective compositions have been prepared by combining a mass of glass fibers into an intumescent paint; advantageously, these fibers are precoated with a vinyl resin such as polyvinyl chloride. Even such compositions, however, will eventually break down after long exposure to elevated temperatures, particularly at corners, sharp edges, and other irregularly surfaced areas.
An object of the present invention is to provide an improved fire-retardant and heat-resistant protective coating.
Another object is to improve the effectiveness and durability of protective compositions including glass fibers and an intumescent paint, and particularly to reduce the tendency of such compositions to peel or crack at sharp edges.
Another object is to provide an improved method of applying such protective compositions to various surfaces, including steel, wood, and hardened plastics, which will increase the heat and fire-retardancy of these compositions over ~hat achieved with conventional coating procedures.

Thus, the invention in broad aspect provides an assembly comprising (A) a substrate having corners or other sharp edges, ~B) an intumescent coat-ing adherent to the substrate and deposited from a paint consisting essential-ly of a volatile liquid vehicle, 35-150 parts by weight of a resinous film-forming binder, 120-475 parts by weight of a solid spumific, and 2-30% by weight of glass fibers, based on the weight of the other ingredients, and (C) a flexible, permeable, conformable, incombustible fabric sheet bonded to the intumescent coating by the permeation and subsequent drying of the coating.
In a second broad aspect there is provided a process which comprises (A) applying to a substrate surface having corners or other sharp edges an intumescent paint in the average dry thickness of at least about 1/16 inch, said intumescent paint consisting essentially of a volatile liquid vehicle, 35-150 parts by weight of a resinous film-forming binder, 120-475 parts by weight of a solid spumific, and 2-30% by weight of glass fibers, based on the weight of the other ingredients, (B) applying over the paint a flexible, permeable, conformable, incombustible fabric sheet, and (C) allowing the paint to dry to adhere the intumescent composition to the substrate and to the fabric.
The coating may be dried either before or after applying the protective layer. In preferred embodiments, this protective layer may consist of an incombustible fabric, such as fiber glass cloth; a combustible fabric coated with an overcoating of intumescent paint; or an incombustible fabric coated with an overcoating of intumescent paint. The overcoating intumescent paint may, but need not also be combined with glass fibers.
Also, 10% or more of the fibers in the protective composition may be glass fibers precoated with polyvinyl choride.
Any of the known intumescent paints are suitable for use in the present invention. Among such paints are those described in United States Patents 2,452,054; 2,452,055; 2,523,626; 2,628,946; 2,702,283; 2,917,476;
30 2,956,037; 2,984,640; 3,037,951, and 3,284,216. In general, such intumescent paints include a volatile liquid vehicle or ` 5199-CAN

carrier in which the remaining ingredients are dissolved or dispersed and which evaporates as the paint dries, a film-forming material or binder, preferably a synthetic resinous binder, which serves to bond the remaining ingred-ients to each other and to the surface of the substrate when the paint is dry, and one or more spumific agents which react, upon heating to an elevated temperature of the order of 125 to 400C or even higher, with each other or with the binder or with some product evolved by heat-decomposi-tion from the binder to cause the mass of the dried paint layer to puff or swell up into a foam-like mass at least four times as thick as the original dried paint layer. The binder may be present as a preformed material or in the form of two or more separate ingredients which react with each other to form a resinous binder as the paint driés, such as a mixture of urea or thiourea or dicyandiamide or melamine with an aliphatic aldehyde (or source of aldehyde) such as formaldehyde or paraformaldehyde or trioxymethylene (or hexamethylene tetramine) or acetaldehyde or furfural.
Other binders which may be used either alone or in combin-ation with the foregoing include drying oils; alkyd resins;
cellulose derivatives such as esters or ethers, e.g., cellulose acetate or butyrate, ethyl cellulose, or hydroxy-ethyl cellulose; sodium carboxymethyl cellulose; starch; a chloride-containing organic polymer such as chlorinated rubber, rubber hydrochloride, polymers and copolymers of vinyl chloride or of vinylidene chloride, e.g., polyvinyl chloride, copolymers of vinyl chloride with vinyl acetate, polyvinylidene chloride, copolymers of vinylidene chloride with vinyl cloride or vinyl acetate, polychloroprene; epoxy resins; and other similar materials. The spumific agent 519 9eCAN
~066180 may be dicyandiamide or melamine pyrophosphate, mono- or di-ammonium phosphate, phosphoric acid, guanyl urea phosphate, ammonium sulfate, sulfamic acid, ammonium sulfamate, ammonium bromide, sodium tungstate, boric acid, sodium borate, poly-ph~spho~ylam~de, and wa~er-insoluble me~aphosphates such as those of sodium, potassium, calcium, or zinc. Melamine pyrophosphate, dicyandiamide, and polyphosphorylamide are particularly preferred.
The volatile liquid vehicle or carrier may be water or an organic liquid such as a hydrocarbon, alcohol, ketone, ether, chlorinated hydrocarbon, etc. The precise identity of the liquid vehicle selected will depend upon its suit-ability for use with the particular binder, spumific agent, and other ingredients present. The vehicle preferably is inert chemically to the remaining ingredients.
Other optional ingredients which may be present in such intumescent paints include carbohydrates, such as starch, and similar materials which are not necessarily film-forming but which are carbonaceous and serve to enhance the effect of the spumific agent, such as a polyhydroxy alcohol, e.g., pentaerythritol, sorbitol, mannitol, dipenta-erythritol, tripentaerythritol, and other similar saturated open-chain polyhydroxy alcohols containing from five to fifteen carbon atoms and from 4 to 8 hydroxyl groups.
Plasticizers for the film-forming binder may also be present in order to increase the film-forming tendencies and to soften the resultant film.
Pigments, fillers, dyes, stabilizers and other conven-tional paint ingredients may also be present as desired, subject to the limitation that excessive quantitles of pigments or fillers tend to cancel out the desirable effects -- , 5199-CAN

of the glass fibers. Surface active agents or wetting agents may also be present, particularly when the vehicle is water, in order to promote dispersing of the remaining ingredients in the vehicle. Chlorinated organic materials which decompose to liberate hydrogen chloride when heated to temperatures of the order of 125 to 400C or even higher may also be present, as for example chlorinated bi- or tri-phenyl or chlorinated paraffin waxes. Chlorine-contain-ing binders, when present, may decompose in the same fashion.
A non-film-forming aldehyde resin in finely divided partic-ulate form, such as urea-formaldehyde or melamine-formalde-hyde resins, which is insoluble in the vehicle and in the other ingredients present, may also be present.
The relative proportions of the ingredients present in addition to the inorganic fibrous material in the in-tumescent paint may vary over a wide range. Best results are generally obtained when the proportions in parts by weight are within the following ranges:
Film-forming material or binder----------- 35 to 150 Spumific----------------------------------120 to 475 Carbonaceous materials, whether or not they are film-forming, when present in addition 'co other film-forming materials, are preferably present in the range from 40 to 250 parts by weight while chlorinated material (non-film-forming) when present in addition to other film-forming materials is preferably in the range from 70 to 220 parts by weight.
The amount of liquid vehicle or carrier may vary over a wide range depending upon the desired mode of application of the paint, the nature of the surface or substrate to it is to be applied, and the nature and quantity of any optional ingredients which are present. The finely divided 1~366180 non-film-forming aldehyde resin, when present, may be used in the same range of proportions as the carbonaceous material.
The several ingredients are normally dissolved or dispersed in the volatile liquid vehicle or carrier, to provide a liquid paint or coating composition which is adapted to be spread or applied to the surface of the substrate to be protected in any conventional manner, as by brushing, roller applying, spraying, etc. The relative proportions of solid ingredients and liquid vehicle or carrier employed will be largely a matter of choice and will depend at least in part upon the mode of application of the composition to the substrate.
Protective compositions including an intumescent paint and glass fibers are described in United States Patent No. 3,284,216. The intumescent paint consists essentially of a volatile liquid vehicle, 35 to 150 parts by weight of a resinous film-forming binder, and 120 to 475 parts by weight of a solid spumific agent which when heated to an elevated temperature of the order of 125C to 400C or even higher causes dried film of the paint to increase in thickness at least four times. In the protective composition, there is mixed into the paint from 2 to 30% by weight ~exclusive of organic coating on the fibers), based on the remaining paint ingredients, of glass fibers, generally from one-tenth inch to as much as six inches or more in length, those from one-quarter to one inch in length being preferred as giving optimum results. The individual fibers may be dispersed in discrete form or as a randomly oriented mass throughout the mass of the composition, or yarns of about the same length composed of several individual fibers may be dispersed in the composition.
For use in the present invention, the glass fibers may r- - 7 -~.

1066~80 be provided by mineral wool ~commercially available as e.g., "Blowing Wool", "Pouring Wool", "Thermafiher* Spray Wool", "Spintex*", "Banrock*") containing glass fibers and, often, also "shot", or glass fragments. Where the protect-ive composition is to be sprayed by a nozzle, to avoid clogging the shot should preferably be refined out of the glass wool.
Excellent results have been obtained with commercially available refined mineral wools such as with Superglas* 1000 and Superglas* 1500 having a fiber diameter of 3 to 5 microns; these fibers are readily wetted with aqueous solutions and do not adsorb liquids. However, similar results may be obtained by refining or otherwise removing the "shot" from raw mineral wool.
Glass fibers having larger diameters, up to 100 to 200 microns or even more, may also be used. Glass fibers precoated with a vinyl resin such as poly-vinyl chloride or the like (Fiberglas screen yarn) in order to facilitate the dispersion of the fibers in the composition and to ensure that the composition may be readily sprayable in conventional spray equipment may also be used. The amount of vinyl resin coating on the fibers may range upwardly of 100% by weight of the inorganic portion. Usually, in compositions includ-ing coated fibers, at least about 1% of the total glass fiber weight thereof is coated fibers. Uncoated fiber glass may also be used although, where the protective composition is to be applied by spraying, the amount of uncoated fiber glass should not exceed about 1/2% by weight of the remaining paint ingredients.
The total glass fiber weight ~not including the weight of any coating on the fibers) may range up to about 30% by weight of the remainder of the composition, including vehicle, without seriously impeding the spray-ing characteristics of *Trademark the mix. Even higher proportions of fibers may be employed if specially designed spray equipment is available or if the composition is applied to the surface to be protected by some other method, as for example by trowelling. When the total glass fiber weight (exclusive of any fiber coating) amounts to less than about 2~ of the weight of the remainder of the composition, it has little effect on the properties of the composition. Optimum effectiveness is obtained with compositions in which the bare glass fiber amounts to 8%
to 25% by weight of the remainder of the composition, includ-ing solvents. Asbestos or ceramic fibers are not equivalent to glass fibers in the present invention and do not, by themselves, produce the improved results of the present invention. However, a limited ~uantity of asbestos or ; ceramic fibers, as well as of other inorganic fillers such as clay, may be present in addition to glass fibers; in some cases their presence may be desirable to provide for optimum spraying characteristics of the paint. As the amount of asbestos or ceramic fibers present is increased they have a deleterious effect which tends to cancel out the beneficial effect of the glass fibers. In general, the amount of conventional asbestos or ceramic fibers or of other inorganic fillers should not exceed about 80% by weight of the glass fibers present (exclusive of the weight of any coating on the fibers) for best results.
After drying by evaporation of the volatile solvents, the bare weight of the glass fibers amounts to about 16%
to 50% by weight of the remainder of the protective composi-tion (i.e., of the remaining solids content), preferably 30~ to 40% by weight.

;6~80 The fabric sheet employed may be itself either combustible or non-combustible. It may be lightweight, and, where woven, of a relatively open weave. Since the fabric sheet is most advantageously utilized at corners and other sharp edges, it should be flexible and conformable to such edges.
Moreover, the fabric must be sufficiently permeable to receive a paint applied on either side, so as to unite with that paint, yet strong enough to become wetted with the paint without tearing, shredding, disintegrating or otherwise losing its fabric structure.
A preferred non-combustible material is a relatively open weave fiber glass cloth. However, combustible natural or synthetic fabrics may be used, including cotton cloth and certain oiled cloths ~such as "WALLTEX" *, a material including canvas and a number of baked-on oil coatings manufactured by Columbus Coated Fabrics Corp., Columbus, Ohio). Preferably, the fabric should have a small charring tendency, since charring weakens the fabric strength and hence weakens its reinforcing qualities. The strength of these fabrics (and hence also the~r resistance to shredding or tearing under elevated temperatures) may be further improved by applying a resinous coating to the fabric fibers.
Where a combustible fabric is employed, this fabric must be further coated with a fire-retardant and heat-resistant coating, such as an intumescent paint as described above, or a protective composition including an intumescent paint and glass fibers, some or all of which may be vinyl coated depending on the desired aesthetic appearance of the final surface coating. Preferably, however, even incombustible fabrics are thus coated, to provide a stronger, more uniform fire-retardant and heat-resistant coat-ing. The fabric is united with either the underlying composition ~if wet when fabric is applied) or *Trademark 1066~80 with the overcoating by seepage of liquids from the protective composition or intumescent paint into the fabric, later drying of the composition or paint thus uniting the fabric therewith.
Where only corners or edges are to be covered, a suffi-e~ v~ p ~ fabric should be e~p~oyed so tha~ the é~a~si~
of the intumescent paint of the underlying pxotective com-position layer, will not cause that layer to shed the fabric.
Preferably, at least about a 6 inch wide sheet of fabric is used to cover a corner or edge, 3 inches overlapping on each side of the corner. Where overall fabric protection is deslred because of the extreme conditions of contemplated use for the underlying surface, or, for decorative purposes such as achieving a smooth, wallpaper-like coating, the entire surface is covered, over the protective composition including an intumescent paint and glass fibers, with fabric, the underlying composition allo~ed to dry, and the fabric covered with an overcoating of an intumescent paint, which need not be combined with glass fibers, and for smooth coatings, is not so combined. However, fabric may be applied to either a wet or a dry protective composition (wet compositions, of course, aiding application), and the overcoating paint applied either before or after drying of the base protective compo-sition.
For sufficiently lengthy protection of the surfaces against temperatures which may exceed 1800F, at least about a 1/16 inch layer (dry thickness) of protective composition should be applied to the surface to be protected beneath the fabric; a dried layer of about 3/8 inch is an effective practical depth, affording maximum protection without employ-ing an excess of the protective composition.

~66~80 Other objects, features, and advantages of the present invention will appear from the following specific examples, which are not intended as a limitation on the scope of the invention.

Example 1 A lO inch steel I beam was prepared in accordance with the ASTM E-119-58 procedure, which tests the deflection of steel beams under an applied load. For the present exampleJ a temperature of 1000F was taken to be the temperature at which this steel beam would deflect. Thermocouples were attached to three locations in the steel beam sample to give an average temperature, and another thermocouple was inserted in a furnace (the furnace being also as prescribed by ASTM E-119-38).
This steel sample A was covered with about 3/8 inch of dried protective composition having the following ingredients of parts by weight:
Parts Chlorinated Rubber 15 Aromatic hydrocarbon solvent (Amsco*D) 85 Dipentaerythritol (carbonaceous) 9 Melamine pyrophosphate (spumific)30 Glass fibers (refined mineral wool) 9 A second steel sample B was prepared, with identically attached thermocouples, and coated also with 3/8 inch of the above protective composition. However, this paint was overlayered with an open weave fiber glass cloth while wet and allowed to dry; a further overcoating of an intumescent paint having the following composition in parts by weight, was then applied:

*Trademark ~ , ~066180 Parts Chlorinated Rubber 15 Aromatic hydrocarbon solvent (Amsco* D) 85 Dipentaerythritol (carbonaceous) 9 Melamine pyrophosphate ~spumific) 30 The steel samples were then heated and the temperatures recorded by the thermocouples at suitable intervals. The following results were obtained:

Temperature of Furnace Temperature of Sample B
Time Temperature Sample A (fiber glass cloth) (Mins.) F F F

1580 860* 340 1610 over 1000 370 *Coating fell of the steel at this point.
Example 2 Two steel samples identical to those described in ~066180 Example 1 were prepared. Sample C was coated with a 3/8 inch layer of a protective composition such as described in Example 1 except that instead of 9 parts glass fibers, there were used 4.5 parts glass fibers (refined mineral wool) and 4. 5 parts o~ O .1 to 1. 0 lnch long glass flbers precoated with polyvinyl chloride to assume a rod-like structure (Fiberglas screen yarn).
Sample D was coated with a 3/8 inch layer of the same protective composition and with open weave fiber glass cloth, and was overcoated with the intumescent paint described in Example 1. The samples were heated and temperatures measured at 5 minute intervals, as described in Example 1. The results are summarized below:

Temperature of FurnaceTemperature of Sample D
TimeTemperatureSample C (fiber glass cloth) (Mins.) F F ~ F

.. ...

50 i660 510 420 30 100 1820 950* 680 -~66~80 *At about 103 minutes, the steel reached 980, and heating was ceased.
A comparison of Examples 1 and 2 shows that although protective compositions including an intumescent paint and ~nco~ted glass fibers ~refined mineral wool) make far poorer fire-retardant coatings than protective compositions contain-ing some vinyl coated glass fibers (compare Sample A and Sample C), yet when identical layers of these two protective compositions were overlayered with fiber glass cloth and coated with an intumescent paint, the fire-retardant properties of the resultant multi-layered protective coatings were markedly similar (compare Sample B and Sample D).

Example 3 Three steel samples E, F, G, such as described in Example l,-were prepared and all were covered with a 3/8 inch layer of the protective composition described in Example

2. Samples F and G were also covered with a layer of fabric, and an overcoating of the intumescent paint described in Examples 1 and 2. The fabric was "WALLTEX" (a fabric wall covering consisting of canvas and a number of baked-on oil coatings, manufactured by Columbus Coated Fabrics Corp., Columbus, Ohio) in Sample F and woven cotton cloth in Sample G. The results are summarized below:

10661~30 Temp. of Temp. of Furnace Temp. of Sample F Sample G
Time Temp. Sample E ("WALLTEX") (cotton cloth) (Mins.) F F F F

_ 100 1820 950* 750 780 *At about 103 minutes the steel reached 980; and heating was stopped.
Other embodiments will occur to those skilled in the art and are within the following claims.

Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An assembly comprising (A) a substrate having corners or other sharp edges, (B) an intumescent coating adherent to the substrate and deposited from a paint consisting essentially of a volatile liquid vehicle, 35-150 parts by weight of a resinous film-forming binder, 120-475 parts by weight of a solid spumific, and 2-30% by weight of glass fibers, based on the weight of the other ingredients, and (C) a flexible, permeable, conform-able, incombustible fabric sheet bonded to the intumescent coating by the permeation and subsequent drying of the coating.

2. The assembly of claim 1 wherein said intumescent coating covers at least three inches on each side of a corner or other sharp edges.

3. The assembly of claim 1 wherein the side of the fabric sheet opposite the glass fiber-filled coating is integrally bonded with a second intumescent coating by the permeation and drying of the coating, the second intumescent coating being deposited from a paint consisting essentially of a volatile liquid vehicle, 35-150 parts by weight of a resinous film-forming binder, and 120-475 parts by weight of a solid spumific.

4. The assembly of claim 2 wherein the side of the fabric sheet opposite the glass fiber-filled coating is integrally bonded with a second intumescent coating by the permeation and drying of the coating, the second intumescent coating being deposited from a paint consisting essentially of a volatile liquid vehicle, 35-150 parts by weight of a resinous film-forming binder, and 120-475 parts by weight of a solid spumific.

5. The assembly of claim 3 or 4 wherein the fabric sheet is woven glass fiber cloth.

6. The assembly of claim 3 or 4 wherein, in each of the paints, the binder is chlorinated rubber and the spumific is melamine pyrophosphate.

7. The assembly of claim 3 or 4 wherein each intumescent paint also includes 40-250 parts by weight of dipentaerythritol.

8. The assembly of claim 3 or 4 wherein at least some of the glass fibers are coated with polyvinyl chloride.

9. The assembly of claim 3 or 4 wherein the second intumescent coating also includes 2-30% by weight of glass fibers, based on the weight of the other ingredients.

10. A process which comprises (A) applying to a substrate surface having corners or other sharp edges an intumescent paint in the average dry thickness of at least about 1/16 inch, said intumescent paint consisting essentially of a volatile liquid vehicle, 35-150 parts by weight of a resinous film-forming binder, 120-475 parts by weight of a solid spumific, and 2-30% by weight of glass fibers, based on the weight of the other ingredients, (B) applying over the paint a flexible, permeable, conformable, incombustible fabric sheet, and (C) allowing the paint to dry to adhere the intumescent composition to the substrate and to the fabric.

11. The process of claim 10 wherein the intumescent paint is applied so as to cover at least three inches on each side of a corner or other sharp edge.

12. The process of claim 10 wherein the exposed side of the fabric sheet is coated with a second intumescent paint consisting essentially of a volatile liquid vehicle, 35-150 parts by weight of a resinous film-forming binder, and 120-475 parts by weight of a solid spumific.

13. The process of claim 11 wherein the exposed side of the fabric sheet is coated with a second intumescent paint consisting essentially of a volatile liquid vehicle, 35-150 parts by weight of a resinous film-forming binder, and 120-475 parts by weight of a solid spumific.

14. The process of claim 12 or 13 wherein the fabric sheet is woven glass fiber cloth.

15. The process of claim 12 or 13 wherein at least some of the glass fibers are coated with polyvinyl chloride.

16. The process of claim 12 or 13 wherein the second intumescent paint also includes 2-30% by weight of glass fibers, based on the weight of the other ingredients.