AU522017B2 - Intumescable fire-retardant products - Google Patents

Description

Or 7 2UALU&W

ioMrNNESOTA MINING AND MANUFACTURING COMPANY

378 95/7# ot 3M Center, Saint Paul, 'Miri.nesota, 'Jnited Stats of America

hereby -pWy for the grant of 1i Patent for an invention entitled "INTUMESCABLE FIRE-RETARDANT PRCiA. )CTSI"

U lZ~S

Which isdscie in the mnpete 'Vecifiration. This -application is a Con on Application and is based on the appication nuhibeed 814, 493

for a patent or simil~r protection made in United States of America

on 11th July, 1977

C;C' C

CCC tu addreu for service is:

Care: SPR:USON FERGUSON PATENT ATORNEYS iCommon Seal of ESSO HOUSE, 1217 KENT STREET ofAN SYDNEY, NEW SOUTH WALES. MNSOTA NININ GADAUSTRALIA. U14k'ADI 3 hefeto af f i xed in 3 prestaneaD& 16th day of May 19 78

alter,", Ja ww t Sacro ary Snaueof Applicnt Robert Norn Wolfe Vs i at a Vio President

913.803

PATONTC ACT IM24S 0

0MARATIP441-W, 04PM Wl F A MNONTION APPLCAT NNF0APPY0 PATENT OF ADDMT I n suiprt of di. Conton AM~liation made for a Patent ptnfor an iowention entitled 389 7 "INTUMESCABLE FIRE-RETARDANT PRDUTS

Pu am me 1, Robert Norman Wolfe, diam Kma, Care of Minnesota Mining and Manufacturing 'Company :p1r- 3M Ce~nter, Saint Paul, Minnesota, United States of America do solemnly and siwv.rely declare as follows:

(or, in the case of an app~latiow~ by a body corporate) 1. 1am authorised by MINNESOTA MINING AND MANUFACTURING COMPANY the applicant for the patent P-IIN! t M~imic.- to make this declaration on its behalf.

[NO mintry and 2. The bAsic application as defined by Section 141 of the Act was made in 66b of bideap* coin ASlidr!"of United States of America on the w qvx 11th day of Jtily 19 77 by Jean I. Lodge a.4 legal representative of deceased inventor James R. Lodge and Joseph Graham

3.wamuuft~euW&4e--vw ti bsO v~kiaw (or where a person other thian the inventor is the aprlicant) NO sa "ad ad- 3. Joseph Craham, c/-iMinnesota Mining and Manufacturing Company, 3M Center, Saint Pauil, Minnes!Dta, United States of America, and James Robert Lodge, (dece'-seJ formerly of Minnesota Mining and Manufacturing Company, 3M Center, Saint Paul, Minnesota, United States of America

are4s the actual ',nv'tntosof the invention nd the facts oppi[Owhich' the applicant is/me entitled to make the application anc FoH9%wWa*, ft 0 Thb said Company is the ass' b the inventcr Joseph Graham and the assignee of Jean I. Lodge who is the legal representativ'-- of the deceascd inventor.

4. The basic application referred to in paragraph 2 of this Declartion wgis the first application made in a Conventiori country in respect of the invention the subject of the applicatio!. Pal Declared at Minnesota, this 16th -r Ia of May 1971 U.S.A. 4 JUt attire of Applint'Po Norman Wolfe anident Robert Norman Wolfe, Vice President

.113t803-

workers is to introuuce a layer of intuinescable particles e ~s into -the roofing, which, as stated in Doregan, U.S. Pat. II vin n

(12) AUSTRALIAN PATENT ABRIOGNEAT (19) AU (11) AU-81-37 895/78

(54) INTUMESCABLE FIRE-RETARDANT PRODUCTS (71) MINNESOTA MINING AND MANUFACTURING COMPANY (21) 37 895/78 522 017 (22) 10.7.78 (23) 10.7.78 (24) 11.7.77 (31) 814493 (32) 11.7.7) (33) US (43) 17.1.80 (44) 13.5.82 (51)2 EO4D 5/12 E04B 1/94 C09K 3/28 (72) JOSEPH GRAHAM AND JAMES ROBEPT LODGE (deceased) (74) SF (56) 32033/77 C09K, C08K, EO4B, B27K, C08G, B32B 18494/76 499 990 DO6N, DO6M, E04D, E04B 67174/74 486 174 19.61, 88.4

(57) Intumescatb' particles useful in roofing materials are also claimed.

Claim 1. Fire-retardant, intumescable roofing material comprising, in parallel layers, a roofing felt; at least one asphalt coating disposed above the felt; a layer of roofing granules partialUy embedded in the top asphalt coating in the roofing material; Rnd a layer of intumescable particles disposed within the roofing material, said particles having diameters of at least 25 micrJmeters and comprising, at least in a core of the particles, hydrated soluble silicate glass.

01 16*3

OF AIU E (P ~CeA@WEALT14 PATENTS ACT 195?-0 21 Form

OOMPLETE SPECIFIOATION, (OAIGINAL) FOR OFFICE USE:

3789 51 Class Int. Class Application NWomber Lodged

Complete Specification Lodged Accepted Pu'Ldished

§elctfe Art:

tWamevif Applicant MINNESOTA MINING AND MANUFACTURING C(VPANY

Aldress of Applicant 3M Center, -Saint Paul, Minnesota,. United States of Amer,,ca

Artual Inventors: JOSEPH GRAHAM and JAMES ROBERT LODGE (deceased)

Address for Sr i ce: Swruson Ferpomn, Paton Attonevs,

4-4;wree~rt, Sydnev, New Srjuth Wales, 200 Autrle U'

Ce4mp~et* Specification for the inventiom entitlecl t ITMSAL FIRE RET6.bANT PRIODUCTS"

The following -statement is a full description of this invention, iincluding the best method of performing It know to se/us paJtMUI 01 Appacan To: Robert Norman Wolfe Of Jatt Vic President

.r C S. \3 I913

INTUMESCABLE FIRE-RETARDANT PRODUCTS

Despite many efforts over the years, there has

never been a fire-retardant asphalt roofing material having

the same widespread acceptance as standard, non-fire-

retardant versions.

The prior efforts have taken several directions:

use of mineral fibers as a filler in the asphalt layers or

as a replacement fiber in the roofing felt for the purposes

of reducing combustible material and limiting flow and ex-

posure of aFphalt during a fire (see Fasold et al, U.S. Pat.

2,555,401; Tomlinson et al, U.S. Pat. 3,332,830; and

Schuetz, U.S. Pat. 3,369,956); inclusion of chemical fire- retardant agents in the roofing (see Tomlinson and Bierly,

U.S. Pat. 2,667,425); and/or use of extra or heavier layers

of roofing granules. Some of these approaches have pro-

''0 15 duced commercial roofing sufficiently fire-retardant to e

be rated Class A by Underwriter's Laboratory (in contrast

to the Class C rating of standard asphalt roofing); but

even those approaches are not the answer the art is seeking,

since they either greatly increase the cost of roofing,

20 require special manufacturing equipment or processes, or

provide only marginal fire protection. As an example of

the latter deficiency, some commercial roofing materials

with glass fiber felts pass Underwriter's Laboratory's

"burning brand" test on 3/4-inch-thick (2-centimeters-

thick) roof decks, but they will not pass the test on 3/8-

inch-thick (1-centimeter-thick) roof decks, which are now

approved for use in construction.

A diffetant approach tried by several prior

TO: Robert Norman Wolfe, Vice President

2 workers is to introduce a layer of intumescable particles

into the roofing, which, as stated in Donegan, U.S. Pat.

2,782,129, is intended to expand in the presence of a fire

to form "a fire resistant support or rigid sponge which

absorbs the asphalt, preventing flow and providing an ef-

fective fire barrier to the underlying roof." Donegan

suggests use of unexpanded vermiculite as the intumescable

material, disposed as a particulate layer between two layers

of asbestos-filled asphalt. Bick et al, U.S. Pat.

j:B 10 3,216,883, also suggests the use of vermiculite, either

unexpanded or partially expanded, in "built-up" roofing

(formed in place on a roof). Hinds, U.S. Pat. 3,365,322

(1968), cites disadvantages of vermiculite (it is expensive

and, because of its low weight, is difficult to incorporate

into roofing in uniform amounts), and suggests replacing

the vermiculite *ith mineral granules that carry an intu-

mescable coating of sodium silicate and borax.

None of these efforts with intumescable roofing

f. have been as effective as some of the other described ap.-

proaches. Roofing material as taught in K'nds was com-

merically sold for awhile, but without apparent success. Very little intumescence was provided by the coated

granules, and fire-resistance appeared to depend on

presence of asbestos fibers as a filler in the asphalt;

such a filled asphalt is difficult to apply by standard

coating equipment, is costly, and has toxicity and other

disadvantages. In addition, the coated mineral granules

were flood-coated into the roofing material at weights of

100 to 125 kilograms per 10-by-10-meter section of applied

UU.

roofing, adding to cost anO weight of the roofing. Also, the coating on the granules was soluble in water, and in the nearly

continuous flood-coated layer was especially susceptible to

leaching and consequent loss of intumescability.

Vermiculite as suggested by Donegan and Bick also

o-fers only low-volume intumescence; and vermiculite will not

intumesc until a fire has progressed sufficiently to create

high temperatures.

In brief, nothing in the known prior work with

iC intumescable roofing suggests that intumescence could be the

basis for an effective and economical fire-retardant asphalt

roofing.

In the broad form the present invention provides a fire-

retardant, intumescable roofing material comprising, in parellel

layers, a roofing felt; at least one asphalt coating disposed

above the felt; a layer of roofing granules partially embedded

in the top asphalt coating in the roofing material; and a layer

of intumescable particles disposed within the roofing material,

said particles having diameters of at least 25 micrometers and

comprising, at least in a 25-micrometer-diameter core of the

particles, hydrated soluble silicate glass.

In another form the present invention provides moisture

resistant particles useful for manufacturing the above roofing

material which particles comprise and at least

diameter core particle that comprises hydrated soluble :ilicate glass, and a protective moisture-resistant coating surrounding

the core particle; the protective coating including an ingredient ;i that is ionized in the presence of water to provide metal cation

Sapable of reacting with the silicate ion of the core particle 3f to form a reaction product that is less water-soluble than the

~~2ii (44

Also, the

in the nearly silicate glass of the particle, thereby limiting action of

tptible to water on the core particle.

In a preferred form the present invention also

Bick also provides moisture-resistant particles that intumesce in large

te will not volume when exposed to heat comprising core particles, at least

to create 90 volume-percent of which are between 0.1 and 2 millimeters in

diameter, which comprise hydrated sodium silicate glass having

k with a silicate-soda ratio of at least 2 to 1, heating to about 3000C., 4.4 4444c 4

uld be the 4'1* and a moisture-resistant protective coating surrounding the core J40X~ asphalt 44 44. particle and comprising a metal cation capable of reacting with 4r 44 4 the silicate ion of the core particle to form a reaction

provideis a fire- product less water-soluble than the silicate glass of the core

g, in parellel particle, thereby limiting action of water on the core particle.

ng disposed The roofing material, which is of the intumescable type,

Ily embedded offers an economic and effective fire-retardancy that promises a oi o B ani a layer widespread iitility for the :oofirg material. In basic sC

a 44

ing material, 44 44 constructions, the new roofing material can be like previous

rometers and intumescable roofing materials, i.e. it generally comprises a

Dre of the roofing felt; at least one asphalt coating above the felt; a

layer of roofing granulhs partially embedded in the top asphalt

wvides moisture coating on the roofing felt; and a layer of intumescable particles

jove roofing disposed within the roofing material so as to intumesce when the

nicrometer- roofing material is exposed to fire. Also, the intumescable

ible ,ilicate material in the new roofing material is hydrated soluble

surrounding silicate, which, as indicated above, has previously been used in

an ingredient fire-retardant roofing as a coating on mineral granules.

metal cation Notwithstanding such similarities, roofing ma-

)re particle

)le than the

3A

k. 44 44

o

17

al- hardens to a solid coating upon exposure as a thin coating de can 4- vAoarimiled environments. Also, the particles can be

S4

terial of the invention is effective where prior-art intu-

Mescable roofing has not been. A first difference over

prior-art intumescable roofing is that the intumescable

particles in roofing material of the invention comprise

hydrated soluble silicate at their core, rather than in a

peripheral coating as in the prior-art coated mineral

granules. Despite previous work in the art with hydrated

soluble silicate, there has never, so far as known, been a

commercially available hydrated soluble silicate in par-

ticulate form such as used in roofing material of the

invention, nor has such particulate hydrated soluble sili-

cate been suggested as an intumescable fire-retardant

additive. We have succeeded in providing a commercially

practicable method of manufacture of such particles (as

will be subsequently described), and have found that when

the particles are included as a layer in roofing material,

they provide a fire-retardancy far superior to that pro- vided in any previous intumescable roofing.

Another reason for the superior intumescence of

roofing material of the invention is the protection given

the hydrated soluble silicate glass particles against

attack by moisture. Moisture will leach away alkali metal

oxide from soluble silicate particles and take away their

ability to intumesce. Some protection against such attack

can be provided with extra-heavy layers of asphalt, extra-

high concentrations of intumescable particles, or construc-

tions in which the particles are sandwiched between imper-

meable films. The effectiveness of these procedures is

assisted by the concentrated nature of the intumescable vidual intumescable particle in roofing material of the invention intumesces in large volume, fewer particles need be used and the particles can be better surrounded and isolated by moisture-resistant structure.

However, the present invention achieves even

more effective moisture-protection with a novel hydrated

soluble silicate particle that carries a uniqg'e protective

coating. This protective coating includes an ingredient

S 10 that is ionized in the presence of water to provide metal

cation capable of reacting with the silicate ion of the

core particle. The reaction between the metal and silicate

ions forms a reaction product that is less vrater-soluble

than the core particle, whereby a protective layer is

formed around the particle. The protective coating is

regarded as having a self-healing function, in that any

openings which develop in the protective layer tend to be sealed, thereby limiting action of water on the core par-

ticles and maintaining the intumescent character of the

particles.

The protective coating is also a key to conven-

ient manufacture of the intumescable particles. Prior to the present invention, the art might have considered two

general kinds of method for manufacturing hydrated soluble

silicate particles: drying of commercially available

solutions of soluble silicates to a solid of the needed

water content; and hydration of commercially available

anhydrous soluble silicate material. Doth methods present

difficulties: the drying operation of the first method

7"

6

forms a film that retards evaporation and greatly lengthens

the process; and the hydration step in the second method

tends to form agglomerated glass-like material that is

difficult to comminute to needed sizes. Such difficulties

have now been overcome with the discovery that anhydrous

soluble silicate material, crushed to a desired particle

size, can be coated with the described protective coating

and then hydrated to the desired moisture content under the

heat and pressure of an autoclave, producing ready-to-use

non-agglomerated particles.

In a different manufacturing method, anhydrous

soluble silicate fines can be agglomerated to desired

particle sizes with liquid soluble silicate, coated with

the described protective coating, and Leated to form in-

tumescable hydrated soluble silicate particles (the heating

operation is understood as distributing water present in

the liquid soluble silicate throughout the particle to

make the particle intumescable). Particles formed from

agglomerated fines have the advantage that during intu-

mescence they tend to form a multicellular product, which

has greater crush strength.

A less desirable alternative for manufacturing

particles useful in the invention is to hydrate uncoated

anhydrous soluble silicate particles in a bed of inert

particles such as clay, A protective coating of the in-

vention can be applied to particles that have already been

hydrated, as well as to anhydrous particles.

Because of the moisture-resistant nature of

coated particles of the invention, together with their small size and high degree of intumescence, they can be conveniently and economically included in asphalt roofing materials without significant change of standard manufac- turing procedures. A rather low amount of the particles can be applied per unit area of the roofing material, and the particles can be cascaded directly onto ard partially embedded in asphalt coatings already incorporated into standard asphalt roofing materials.

The amount of intumescence exhibited by roofing

material of the invention can be controlled through se-

lection of the amount of intumascable particles. A rather

low amount of particles gives the roofing material a large

volume of intumescence and a high degree of fire-retardancy.

Roofing material of the invention passes Underwriter's

Laboratory's "burning brand" test on either 2-centimeter

or 1-centimeter-thick decks, and in fact, will pass a more

stringent laboratory test in which a Bunsen burner is

trained continuously for 30 minutes on a 15-by-15-centimeter

sample of applied roofing material overlapped in the

manner that roofing shingles are applied to a roof deck),

but laid over a piece of unsaturated organic felt paper

rather than a roof deck. In neither test does fire pene-

trate through he test sample.

Further, extende' tests of roofing material of

the invention at restricted test sites as well as acceler-

ated aging tests indicate that the described fire-

retardancy is retained over a useful lifetime for roofing.

The total combination of properties is a significant

advance in the roofing material art, and appuars to offer

i i.

I/

8

for the first time the potential for asphalt-saturated,

felt-basee roofing material to be offered in a form that

is both highly fire-retardant and economical.

Besides use in roofing material, coated particles

of the invention can be included in a wide range of ma-

terials ranging from solid foams to liquid coating

compositions. The moisture-resistance and highly intu-

mescent character of the particles make their use conven-

ient and effective, all at moderate cost.

IL' Some additional prior art background for the

prer'nt invention can be summarized as follows:

According to Vail, J. Soluble Silicates

(1952, Reinhold Publishing Company), Volume 2, page 481,

the United States patent literature on intumescence of

soluble silicates begins in 1883 with Kelly, U.S. Pat.

283,789, which teaches a cellular mass of expanded silicate

as a thermal insulation for fireproof safes. Arthur, U.S.

Pat. 1,041,565, issued in 1912, teaches a particulate

soluble silicate such as sodium or potassium silicate which

may be intumesced to form expanded or cellular particulate

material useful as thermal insulation.

The patent literature very early discusses ways

to insolubilize the soluble silicate glasses. Gesner, U.S.

Pat. 419,657, issued in 1890, teaches the treatment of

cellular silicate qlasses with chemical agents such as

calcium chloride; acids such as sulfuric or hydrochloric

acid; and soluble oxides and salt3 of metals other than

alkaline metals, including such oxides as barium or

-trcqntium hydroxide and such salts as calcium or barium

F

9 aturated, nitrite. Gesner also teaches that the cellular material form that may be made impervious to water by coating it with paraffin,

drying oils, asphalt, rubber and fused or dissolved insol- ted particles uble metallic soaps or oleates or stearates, and solutions ,ge of ma- of resins or gums. coating The Hinds patent mentioned above suggests that

[rly intu- the intumescable coated granules may be coated with asphalt use conven- emulsions, oils, silicones, or latex emulsions to prevent

water-absorption by the granules. I for the Another example of prior teachings as to use of

intumescable silicate materials for fire retardancy is .licates Vail's report (page 483) that wooden beams have been coated ,page 481, with heavy silicate solutions to reduce the hazard of f.re. icence of In a different kind of teaching, Cohen, U.S. Pat. J.S. Pat. 917,543 suggests the use of sodium silicate in roofing anded silicate material as an adhesive to bond a sheet of asbestos to a Arthur, U.S. sheet of organic fibers and form a fire and waterproof ticulate material. However, there is no suggestion that the sodium silicate which silicate be particulate or intmescable as in the case in r particulate our new roofing material.

Insofar as known, nothing in the prior art scusses ways teaches asphalt-saturated, felt-based roofing material Gesner, U.S. containing a layer of hydrated soluble '-ilicate pa.ticles atment of for fire-retardancy. Nor does the known prior art teach s such as particulate silicate glasses, not yet expanded but still ydrochloric intunwscable, and coated with a coating that protects and other than increases the expansibility of the particles during int;u- ium or mescence and makes possible their convenient manufacture. or barium Figure 1 is a sectional view through an illus- ri C-~ O

0 I) .o~

10 ular material trative roofing material 10 of the invention. The roofing it with paraffin, material 10 can be made as follows: A roofing felt paper issolved insol- 11 is saturated, and coated on its top surface to form a and solutions layer 12, with an asphaltic composition. Intumescable

soluble silicate particles 13 are cascaded onto the coated suggests that felt where they become partially embedded in the layer 12. ted with asphalt A layer 14 of asphaltic composition is then applied over ons to prevent the particles of the invention; and roofing granules 15 are

cascaded onto the layer 14, where they become partially s as to use of embedded. A back coating 16 of asphaltic composition is tardancy is applied to the bottom of the felt paper 11, and a dust have beev, coated coating 17 of mica or the like is applied to make the back hazard of fI-re. side of the material tack-free. Cohen, Pat. Figure 2 is a sectional view through a repre- in roofing sentative intumescent particle 19 of the invention, which asbestos to a comprises a core particle 20 and a protective coating 21 waterproof surrounding the particle. that the sodium Figure 3 is a graph shewing the amount of intu- in the case in mescence versus water content coated particles of the

invention and particles that are t.e same except for being prior art incoated. ig material Sodium silicates are preferred as the soluble =ate particles silicate glass in intumescable particles of the invention ior art teach because of their lower costs, but silicates formed from led but still other alkali metals may also be Jised, including, for protects and example, those formed from potassiun and lithium. The i during int- silicates used may also have different ratios of silica Smanufacture. to alkali-metal oxide, but silicates having a ratio above igh an illus- about 2 to 1 are preferred because they are less water- u 7! ri. The roofing 11 1 ing felt paper soluble than those of lesser ratios. ace to form a The intumescable particlee can range widely in ntuxnescable size, though as shown in Table I, volu-me of intumescence onto the coated varies with the size of the particles. As the particle size ni the layer 12. Table I. applied over Volubie Intumescence of Sodium Silicate Particles granules 15 are (Si0 2 Na20 ratio of 3.22, and hydrated with 13 percent water) m~e partially Particle Size Volume to which two-milliliter 'Omposition is Rneof-size Averagedlameter s~ileexjands and a dust

;o make the back 2000 2380 2200 200

840 2000 1400 200

)ughi a ropre- 590 840 710 175

ivention, which 15 420 590 500 175

.ve coating 21 297 420 350 160

176 297 230 125

amountt of int'l- 12S 176 150 110

krt~cles of the 88 127 105

xcept f or being 20 70 88 80

62 74 67

the soluble 44 552 53

the -invention Al 40 28 23

formed from ~20 14 3

ding, for 25 1l0 6 3

thium. The reported in the -table rises above minimal values, the~ volume

os of silica of intumesca~nce increases significantly; th3 reported par-

a raUio above ticles that average approximately 25 micrometers in aize

less water- intumesce over ten-fold, and the reported particles that

average approximately 100 micrometers, intumesce over forty- fold. Particles of the invention should intumesce at least four-fold and preferably at least forty-fold for most uses as a fire-retardant additive. For the highest volume- percent of intumescence, particles above about 300 micro- meters in diameter are preferably used (in giving values for maximum and minimum diameter, the values stated apply for only 90 volume-percent of the particles, since after a screening operation some of the remaining particles are outside the screen sizes). For the most satisfactory use in roofing material the particles should average less than

2 millimeters, and preferably less than 1 millimeter in

diameter. However, particles up to several centimeters in

diameter can also be used for special purposes.

The particles will intumesce in different amounts

depending on the amount of water present. Curve 1 in

Figure 3 is a graph of the intumescence at a typical

actuating temperature range about 200 to 300 0 C) for

coated sodium silicate particles generally of the type

described in Example 1 below, but with varying water con-

tent, and Curve 2 is a similar curve for uncoated particles.

(The curves show the volume in milliliters to which a 2-

milliliter sample expands.)

To obtain a useful amount of intumescence the

soluble silicate should generally include at least 3 per-

cent, and preferably at least 10 percent, water. Peak

intumescence for t'i illustrated sodium silicate occurs

at around 15 percent water. With greater amounts of water

beyond 15 percC.nt, intumesconce declines, though it will

occur for contents of water up to, and in fact beyond, the

16*3

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13 at least point (about 30 percent) at vihich the solubie silicate ost uses dissolves in water. Typically, no significant benefits are ume obtaintd by including mcre than 20 percent water. micro- Whereas the core particle in coatled particles of values the invention can he quite soluble in water, the protective d apply coating comprises iigqredients that have a low solubility, after a preferably a rooi-temperature solubility in water of less s are than 0.2 gram/cubic centimeter. However, even with this ory use low solubility, there is sufficient dissociation to provide ass than metal cations for self-healing reaction with silicate ion er in of the core particle. eters in The preferred pxot:,Bt i.a coating, providing the a ar longest-lastirng and most thoxouqgh. moisture protection, com- t amounts prises a 'etal salt of a 1ong-vhain fatty acid. Stearic in a~r

15 acid is the preferred long-cnain fatty acid but others, a aa al a, such as oleic or palmitic acid, can also be used., Also, 00 C) for a a.t aa

although calcium is a preferred metal, other metals, such type 4 a1 as the alkaline-earth metals barium and magnesium, and Br con- aluminum and zinc, can be used. ?articles. 20 In preferred coatings as just described, the best *4 a 2- a water-stability has been obtained when the coating includes

metal, in an ionizable compound, in excess of that needed the *4

for stoichiometric association wgith the anion of the long- 3 per- chain fatty acid. The excess metal of such metal-cation- ?eak a *,a a*

rich coatings can be provided, for example, as the hydrox- :curs o~as

ide, carbonate, chloride, or fluoride of the metal. Typi- )f water cally the exces -metal -providing ionizable compound, which will is desirably preseri in an amount accounting for at least nd, the _ne-half volume-percent of the protective coating, is more

-1 and

um

2 to 1, soluble than the metal salt of the long-chain fatty acid. Other water-insoluble components can be included in protective coatings of the invention, either as a sup- plement or as a substitute for the metal salt of a long- chain fatty acid. For example, organic polymeric films such as polyethylene, polypropylene, wax, epoxy resins, or urethane resins may be used. An ionizable ingredient pro- viding metal cation for reaction with silicate ion of the core particle should be included in such coatings to obtain the best water-stability. A further ingredient preferably included in pro- w tective coatings on particles of the inventi-on is silicone water-repel '.ent agents. A large list of such agents are known to repel moisture from a surface on which they are applied. Use of such a repellent coating has been found to add significantly to the moisture-resistance provided by the protective coating. The long-term stability of coate~d particles of the invention has been demonstrated both in extended aging

20 tests on test decks, and by accelerated laboratory tests in which the particles are totally immersed in water and their intumescability measured at various intervtals. In the

latter kind of testing, for example, sodium silicate par- On ticles as described in Example 1 below, after having been

O 25 immersed in water for 40 days, still exhibit useful intu- mescenice upon heating. When sodium silicate particles the

sww as those of Example 1, but without any protective coating, are subjected 01o the same test, they will not

intumesce at all after 1 3 days of exposure. Also, when

37,895/78

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acid. sodium silicate particles the sameas those of Ex.rTmple 1 acluded except coated with calcium ste~rate in which tLhe calcium a sup- and stearate are in stoichiometric proportions are subjected long- to the same testing, intumescence of the particles declines ilms such after 6 to 9 days to the level exhibited by particles of or Example 1 after 40 days of exposure. nt pro- The protective coating on coated particles can of the be applied by known coating procedures. For example, the o obtain core particles can be mixed with the coating material while

the latter is in a liquid form, e.g. by melting or dis- in pro- solving. The coating is then allowed to harden to a sub- ilicone stantially continuous film, as by cooling, drying or re- s are 00 0

09 4 acting. In one useful coating operation, the core par- y are 0 00 0 04

ticles are first coated with a liquefiable portion of the found 00 44 A

040a 15 coating e.g. melted stearic acid, oleic acid, which is vided by 4 40 0 liquid at room temperature; molten polymer such as poly- 0*o

0 44

04 ethylene; or a liquid uncured epoxy resin-hardener compo- *p 4* es of sition. Then, before the coating has cooled or hardened, d aging 0 0a other ingredients such as the metal-cation-supplying ingre- tests in 20 dient are added, as by mixing a powdered form of that in- y* 00 *4* 4 .nd their 0;

gredient and the coated core particles. For example, the powdered calcium hydroxide is conveniently mixed with par- e par- r* n 0 ticles that have been first coated with molten stearic a*

g been 00000. acid. After such mixing, the calcium hydroxide becomes intu- partially embedded in the stearic acid coating; the calcium 0 4*

:les the reacts with the stearic acid to form nearly insoluble cal- :dve cium stearate; and any unreacted calcium hydroxide remains not present in the layer to provide excess calcium cation for io,when a self-healing function.

S apable of reacting with the silicate ion of the core particle J to form a reaction product that is less water-soluble than the

3

16

Alternatively to the above procedure, metal-

cation-supplying ingredient such as calcium hydroxide can

be incorporated into other ingredients of the protective

coating, such as stearic acid, prior to coating of the core

particles. In the case of calcium hydroxide and stearic

acid, calcium stearate is produced during such a premixing

operation and must be melted before the core particles can

be coated.

As shown in Figure 1, the intumescable particles

in roofing material of the invention need not be closely

packed, since upon expansion they occupy a much arger

volume. Coated particles of the invention can generally be

included in an amount of no more than about 50, and more

commonly are included in nn _amount of no more than about

25, kilograms per 10-by-10-meter section of applied roofing

material. At least 5, and preferably at least 10, kilograms 4 9

of particles are generally used per 10-by-10-meter section.

Though generally embedded in an asphalt coating on the roof-

B. ing felt, the layer of particles may be disposed elsewhere

20 in the r',otng material, in the felt itself.

Besides utility in roofing material, coated par-

ticles of the invention are also useful as fire-retardant

additives in a variety of polymeric articles, including

rigid or flexible foams, molded or sheet articles, extruded

S 25 or cast films, elastomeric articles, etc. Such articles

may be made from polyurethanes, epoxy resins, polyesters,

etc. Also, the particles can be introduced into various

coating materials to form fire-retardant coatings; such

coating materials generally comprise a liquid vehicle that

Iue particle

dle than the

3A

i~n,

17 al- hardens to a solid coating upon exposure as a thin coating de can in predetermined environments. Also, the particles can be ctive added in a loose mixture with other powdered materials for the core fire-retardant purposes. In addition to protecting a sub- earic strate against fire, particles of the invention can perform emixing a heat insulating function; for example, a coating con- les can taining a layer of particles of the invention can be used

to protect steel beams from reaching temperatures during a irticles fire that would damage the beamr and cause them to sag. Losely Also, particles of the invention can be intumesced and :ger used for a variety of purposes; for example, particles can arally be be iutumesced at a building site and introduced into the I n i more walls or other structure of the building as thermal insu- about lation. d roofing The invention will be further illustrated by the kilograms pn~ following examples. U b, section. Example 1 the roof- One-hundred parts of anhydrous sodium silicate a~ a

lsewhere ol 4r glass particles having a SiO 2 :Na 2 O ratio of 3.22 and a u,

range in size from about 300 to 840 micrometers were heated ted par- 4 in an oven to 250 0 F (1200 After reaching that tempera- tardant ture, the particles were Jumped into a cement mixer and 2 uding parts of powdered stearic acid added, whereupon the stearic extruded acid melted and became coited on the particles. After the a) a tides mixing had continued for about 10 minutes, 2 parts of 444,

4a. esters, calrium hydroxide was added and the mixing continued for arious an -dditional 10 minutes. Next, 1 part of a silicone water such repellent (DC-772 sodium siliconate from Dow Corning) was cle that added and mixed in for 10 minutes.

Scoating 18 is can be The coated particles were discharged into trays -ials for to a bed depth of about 5 centimeters. The trays were Lg a sub- loosely fitted with aluminum foil lids and placed in an Ln perform autoclave where they were hydrated at a steam temperature con- of 285 0 F (140°C) for 2 hours. After removal from the auto- be used clave the particles were free-flowing, had a water content during a of 10 weight-percent, and expanded upon heating about sag. fold. Intumescence was measured by gradually pouring 2- I and milliliter-size samples into an aluminum pan heated by a icles can hot plate to a temperature above 400 0 F (205°C), whereupon ato the the particles immediately intumesced. The intumescent al insu- particles were then gathered and their volume measured in

a graduated cylinder. ed by the Particles of the example were incorporated into

a standard roofing material in the manner shown in Figure

1. The weight amount of the various layers was as follows: ilicate 4 U

layer 12, 100 kilograms; layer 13, 15 kilograms; and layer and a 14, 300 kilograms per 10-by-10-meter section of applied ere heated roofing. When the resulting roofing material was tested by tempera- the "burning brand" and more stringent laboratory tests er and 2 noted above, the fire did not burn through the test he stearic samples. After the Samples of the described roofing material were s of B QCCr placed olr roof decks in restricted test sites for five ued for .1*LI L years, and when removed from the deck showed no visible Q t cone water change and again passed the noted "burning brand" and more ing) was stringent laboratory tests.

Example 2 Example 1 was repeated in a larger batch size ditticulties: the drying operation of the first method

19

with a rotary autoclave. Instead of 2 parts of calcium

hydroxide, ]0 parts were used. The larger amount formed

a thicker coating on the particles and made them more free-

flowing without reducing intumescence.

Example 3

Example 1 was repeated except the silicone

water-repellent agent was omitted. When the resulting

particles were tested in the described accelerated aging

test, they exhibited useful intumescence after a

exposure.

Examples 4 and

Example 3 was repeated except that the stearic

acid was rep>.ced with either oleic acid (Example 3) or

palmitic acid (Example In the accelerated aging test

the calcium-oleate-treated particles had a useful life of

6 days in water, and tae calcium-palminate-treated particles

of 7 days.

Examples 6 8

Example 3 was repeated with sodium silicate par-

ticles except that the calcium hydroxide was replaced with

either aluminum hydroxide (Example magnesium hydroxide

(Example or barium hydroxide (Example In the ac-

celerated aging test, the aluminum-stearate-treated par-

ticles had a life of 6 days, and the barium-stearate-

treated particles of 9 days.

Examples 9 and

Example I was repeated except that the sodium

silicate particler were replaced in Example 9 with lithium

silicate (SiO2 :K 2 0 atio of 2.50) and in Example 10 with first method coated particles of the invention, together with their

20

calcium potassium silicate (SiOVY20 2 ratio'of 2.50). Upon heating

mt formed to about 200C, the particles intumesced many-fold.

.m more free- Example 11

Example 3 waz repeated except that 2 parts of

polyethylene low-density polyethylene powder replaced the

Licone stearic acid, and 2 parts of calcium hydroxide were used.

sulting In the accelerated aging test the coated particles had a

ited aging life of 6 days.

a 20-day Example 12

Sixty parts of particles of Example 3 were mixed

into 100 parts of a mixture of Parts A and B of precursors

ie Stearic. (available from Freeman Chemical Corporation, Port

?le 3) or Washington, Wisconsin) that form a pour-in-place, rigid

aging test urethane foam having a density of about 0.032 gram per

Eul life of 15 cubic centimeter. The mixture was poured into trays and

ated particles allowed to cure. After removal from the trays, the cured

samples were conditioned according to the specifications

outlined in Underwriter's Laboratory's tests for flam-

ilicate par- iability of plastic materials, and then subjected to the

aplaced with 20 horizontal burning test for classifying materials (Test No.

hydroxide 94 HEF) and the vertical burning test for classifying

In the ac- materials (Test No. 94 VE-O). In each test tie samples

sated par- passed the test.

earate- Exaple_ 13 Ten parts of particles of Example 3 were mixed

into a mixture of 100 parts polyol (TP740 commercially

he sodium available from Wyandotte Chemical Corporation) and 55 parts

with lithium of polyisocyanate (Mondur MRS commercially available from

le 10 with Mobay). The mixture was then catalyzed by adding 0.3 part with their 'ne totai combination of properties is a significant advance in the roofing material art, and appears to offer

21 Upon heating

fold. lead octoate. Samples were cured and conditioned according

to the specifications outlined in Underwriter's Laboratory's

tests for flammability of plastic materials, and then sub- parts of

eplaced the jected to the horizontal burning test for classifying ma-

5 terials (Test No. 94 HBF) and the vertical test for clas- were used. sifying materials (Test No. 94 VE-O). In each test the cles had a samples passed the test. Example 14

Uncoated sodium silicate particles (SiO 2 3 were mixed

f precursors 10 ratio of 3.22) ranging between 300 and 840 micrometers in

Port diameter and hydrated with a water content of about 14

percent were incorporated into roofing material as shown ce, rigid in Figure 1. Weights were as listed for the roofing mater- gram per ial described in Example 1, except that the layer of intu- trays and

,the cured 15 mescent particles 13 weighed 100 kilograms per 10-by-10-

meter section of applied roofing. After exposure on a test ifications deck for 3 years, the roofing material still exhibited or flam-

ted to the useful intumescence when exposed to a fire.

als (Test No. Example

sifying 20 One-hundred-sixty parts of anhydrous sodium

a samples silicate fines having a SiO2 :NaO0 ratio of 3.22 and a

particle size smaller than about 300 micrometers were

mixed in a Hobart mixer with 40 parts of liquid sodium

silicate having a silica-to-soda ratio of 3.22 and a water nere mixed 25 content of about 62 percent. Agglomerated particles were ?rcially formed and screened to leave particles in a size range of and 55 parts 300 to 840 micrometers. The particles were coated in the Llable from manner described in Example 1 with 2 parts stearic acid Lng 0.3 part and 5 parts calcium hydroxide, and then heated in an oven alkaline metals, including such oxides as barium or jars to offer atrcntlium hydroxide and such salts as caicim or barium

,d according -22

Labor atory I s for about 4 hours. The resulting particlies intumesce-d I then sub- about 50-fold when heated to 300*C. Lfying ma- Alternatively, the particles can be prepared by for cilas- coating the core particles only with calIcium hydroxide and test the 5 no stearic acid, although the particles are not as free- flowing during the hydrating opera,:ion.

io:Na 2 O ometers in bout 14 as shown ofing mater- er of intu-

re on a test hib ited

sodium and a s were sodiumf and a water idles were B range of ted in the ric acid Ln an oven ium or mescence and makes possible their convenient manufacture. Sor barium Figure 1 is a sectional view through an illus- mesced epared by oxide and as free-

17

t

I- U,,

Claims (1)

1. sriicates usea may ai-~u I= ±t manufacture. to alkali-metal oxide, but silicates having a ratio above

   'ugh an illus- ugh 2 to 1 are preferred because they are less water- an illu- about

   The claims defining the invention are as follows;

   1. Fire-retardant, intumescable roofing material

   comprising, in parallel layers, a roofing felt; at least one

   asphalt coating disposed above the felt; a layer of roofing

   granules partially embedded in the top asphalt coating in the

   roofing material; and a layer of intumescable particles disposed

   within the roofing material, said particles having diameters of

   at least 25 micrometers and comprising, at least in a

   meter-diameter core of the particles, hydrated soluble silicate

   glass.

   2. The roofing material of Claim 1 in which said

   layer of intumescable particles weighs between 5 and 50 kilo-

   grams per 10-by-10-meter section of applied roofing.

   3. The roofing material of Claim 1 in which said

   layer of intumescable particles weighs less than 25 kilograms

   per 10-0-meter section of aFrlied roofing. c ll 4. The/eaefi material of any one of Claims 1 to 3

   in which said particles are between abo 0.1 and 2 millimeters

   in diameter.

   The roofing material of any one of Claims 1 to 4

   in which said intumescable particles comprise sodium silicate

   having a silica-to-soda ratio of greater than 2 to 1.

   6. The roofing material of any one of Claims 1 to

   in which said intumescable particles carry a protective

   moisture-resistant coating, which includes an ingredient that

   is ionized in the presence of water to provide metal cation

   capable of reacting with the silicate ion of the core particle

   to form a reaction product less water-soluble than the silicate

   glass of the core particle, thereby limiting action of water on

   the core particle.

   ticles that average approximateLy g a ratio above intumesce over ten-fold, and the reported particles that e less water- average approximatelY 100 micrometers, intuxdesce over forty-

   I 2 0' -1

   as follows; 7. The roofing material oZ Claim 6 in which the pro- ing material tective coating c-rprises a metal salt of a long-chain fatty at least one acid. tr of roofing 8. The roofing material of Claim 7 in which the pro- coatinq in the tective coating further includes metal cation in excess of '3 ticles disposed that needed for stoichiometric association with t2h1 anion ring diameeters of of said salt. ;t in a 9. Moisture-resistant particles useful inter alia soluble silicate for manufacturing roofing material of C-aim 6 compr,.sing an at

   least 25-micrometer-diameter core particle that comprises n which said hydrated soluble silicate glass, and a protective moisture- and 50 k~io- resistant coating surrounding the core paiticle; the protective ing. coating including an ingredient that is ionized in the -n which said presence of watez to provide metal cation capable of reacting in 25 kilograms with the silicate ion of the core particle to form a reaction

   product that is less water-soluble than the silicate glass of )f Claims 1 to 3 the particle, thereby limiting action of water on the core ind 2 millimeters particle.

   Particles of Claim 9 in which the protective )f Claims 1 to 4 coating comprises a metal salt of a long-chain fatty acid 3odium silicare and metal cation in excess of that needed for stoichiometric 2 to 1. assoc:ation with the anion of said salt. )f Claims 1 to 11. Particles of Claims 9 or .1.0 in which the core rotective particle comprises smaller soltible silicate particles bonded Lngredient that together. metal cation 12. Particles of any one of aima 9 to 11 in wbich ie core particle at least 90 volume percent of the core particles are between than the silicate 0.1 and 2 millimeters in diameter. Ntion of water on 13. Moisture-resistant particles that intumesce in I, ,i large volume when exposed to heat comprising core particles, .F n at least 90 volume-percent of which are between about 0.1 and

   2 millimeters in diameter, which comprise hydrated sodium

   silicate glass having a/silicato oa ratio of at least 2 to 1, and which are capable of intumescing at least forty-fold upon

   heating to about 300 0 and a moisture-resistant protective

   coating surrounding the core particle and comprising a metal

   cation capable of reacting with the silicate ion of the core

   particle to form a reaction product less water-soluble than the silicate glass of the core particle, thereby limiting action of

   water on the core particle.

   14. The particles of Claim 13 in which a protective

   coating comprise a metal salt of a long-chain fatty acid.

   The particles of Claims 13 or 14 in which the

   core particle comprises smaller particles of sodium silicate

   bonded together.

   16. Roofing material comprising of roofing felt; at

   least one asphalt coating above the felt; a layer of roofing

   granules partially embedded in the top one of said asphalt

   coatings; and a layer of particles of any one of Claim 9 to 14

   disposed within the roofing material.

   17. A roofing material substantially as hereinbefore described with reference to the accompanying drawings.

   18. A roofing material substantially as hereinbefore

   described with reference to the examples.

   19. Moisture-resistant particles substantially as

   hereinbefore described with reference to the examples.

   DATED this NINETEENTH day of JANUARY, 1982 MINNESOTA MINING AND MANUFACTURING COMPANY

   Patent Attorneys for the Applicant

   SPRUSON FERGUSON

   L VA! ilI

   37, 895/ 78

   17

   ~250

   S so

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   "low

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