US2318574A - Cellular structural material and method of producing the same - Google Patents

Description

106. cowosmous,

COATING on PLASTiC Cross Reference Examine! 88 i irri rmaii' i i j 2,318,574

PATENT OFFICE-,7 fig, I 72,318,574 v Q 4 I t "CELLULAE STRUCTURAL MATERIAL AND- METHOD OF PRODUCING THE SAME I Hart'er, New York, N'. E, Charles L. Norton,

* Boston, Mass and Charles L. Norton, In, New

jf- York, N. Y.; assignors to The Babcock 8t Wilcox Company,'-Newark, N. 1., a. corporation of New g 4, NdDrawing. Application January 26, 1939-: I t h N 252,863 Q I ,.i i, 14CIaims. (Cl.106-;1vffrq J Our inventionrelatestoimprovements inmethquite satisfactory forfuse in a preformed foam" ods of manufacturing light-weight heat resistant proc ss. uch foaming agents have limited abil bodies having a high percentage f, interstitial ty to o m in t p s n e of a'mi t e of solid voids and adapted for useas thermal and sound materials h s required for end pr s of insulating structures, and more particularly to 5 the described charactenassuchmixtures'usually' methods of manufacturing products of the chanin l d S ting agents such as calcined gyp m acter described in which a solidifiable fluid mass r calciumtmaterials, since such materials tend is substantially increased in volume by being in'1-' to form insoluble calcium salts of the fatty acids pregnated with air or ig'as fill'ed void or b bbl of these agents. It has alsobeen'found that most prior to setting.- 7 of such foaming agents disadvantageously affect The products made in accordance with out-ine a on f t e setting agent in e s. with a ventiorr may be*cel1ular', permeable,'fibrous;'reo seq ent'w akeni s of the end p c fractory, oriow thermal conductivity, or of good Processes for manufacturing products u structural strength, or with more than one of l board, Sound i'BSIIIatOIS, e l insulators, thesecharacteristics. When the product is both and'refractories must permi 1 W 005i? quantity permeable and cellular, for example, it i p production to be commercially useful; therefore cially useful asa high grade sound -insulator. y improvements tending 'l p y. cheapeli o'l'h smethods of formin i s r bubbles m or reduce the manufacturing operations required olidiflgbl fluid e heretofore used or u areof substantialadvantage'in this field. I gested in manufacturing methods-or. the chaise go The general obie t invention is the pr terrdescribed can be classified as follows: Vision Of an improved-method 01 ma u actu i .--1' Airjet dispersionintothe a light-weight bodies of the character described). 2. Mechanical agitation of a mass containing which is 'l d i 1 W 0 q ntity commermucilaglnous ingredients, to hold'air bubbles en Cid-I p whichpermits 'a Solidifiable trapped fr m the surrounding atmosphere; I 5 fluid mass containing all of the materials required 3; Inclusion of material in the mass effecting a for e d'esirede'nd product to be foamed in a;

chemical reaction when wet to generate gas bubsinglebpel'ationi 7 bles; and' 1 The various features" of novelty which charac 4. Prefr 1 a stable tenacius f0 =19 t terize our invention are pointed out with particuseparately mixed 0 a 'larity in" the claims annexed to andforming a The first three n; require t solidifiable part of this specification. For a better underfluid mass to be of La sufiiciently h vy n tiif I standing of the invention, its operating advanency, i. e. high viscosity, to mechanically retain ages and specific object's attained by its use, ref

the bubbles'formed until the mass is molded and erence should be had to t e ac yi g deset. Such solidiflable fluid masses do not have a Seriptive matter in which we e described v foaming characteristic, i. e. the capacity when ous embodiments of our invention. i

of low Viscosity and given proper mechanical The best results are; obtained in accordance tation to form a stable structure under atmoswith out invention by employing all of the follow pheric conditio s containing widely. dispersed s fla cambinafio'm voids or bubbles. of the above methods pros 40 Firstly, in of p ndin upon a solidifiable duce substantially similar end products, although fluid mass 'of relatively high viscosityand no e preformed foam method is superior, in uni-v; foaming l fl i P forming a stable formity of dispersion, number and 're'gula'ble tenacious, foam u qi t mixing 'i 'with a of the bubbles produced. These advantages of idififl e d massgwe employ a low viscosity 1' the preformed foam method are however offset solidifiable fluid mass having a foaming oharac-'- from a commercial viewpoint by the lesser. num teristicy v scosity We have in mind such" be! of operating steps,' with consequent savings viscositles as would not permit bubble retention in labor and machineiypf the other methods of by the mass if any of'thefirst three bubble formbubble formation. v ingmeth'ods referred to above were used. With No way has beenfoundto produce'commercially suchvi'scosities the mass is more accurately chara'. satisfactory product of the describedcharactera'cterized as liquid rather than simply fluid by mechanically agitating a solidifiable fluid mass, or' flowabie. By using such solidifiable of heavy consistency containing a foaming agent. of low v'iscosities characterized by a very high per suchas soap. soap bark, saponin, flotation oils, or centage of water in the mixture, end products fatt id sulphonate's, which foaming agents are w a i er P t ge of voids are obtainable tum, -m, if;

due to the greater dispersion of the solid particles in a low viscosity mass, resulting in lighter weight products.

Secondly, instead of using as the foaming agent soap, saponin, flotation oils, fatty acid sulphonates or the like, we employ a synthetic surface active chemical which is a non-soap which causes rapi we ing on of the solid particles in the mixture, which rapidly lowers the surface tension of the liquid, which is completely stable in the presence of alkaline compounds, such as lime or calcium hydroxide, and thus cannot interfere V with either the foaming action or with the subsequent setting action of the hydraulic binder, and V which also produces a bubble wall or film which is considerably stronger than those formed with foaming agents heretofore employed. With such V a foaming agent, the solidifiable fluid mass can be said to have the foaming characteristic heretofore mentioned. We have discovered that the class of synthetic surface active chemicals consisting of sulphonated fatty alcohols, and particularly those orm ng .a huric acid esters i. aWOSOzONa in var ous physical forms and concentrations, form highly suitable foaming agents with the fluidity and agitation conditions used. Suchsynthetic surfaceactive chemicals are sold commercially in the form of dry alkali metal salts gf the sulphonated fatty alcohols. We have found that tfiewy sodififn salt of the sul huric ester of Ian 1 alcohol sold as a detergent under the trade name ful5 hol is a highly effective foaming agent under the operating conditions contemplated. The formula for this is C12Hg O(SOa)Na. The foaming agent employed is preferably incorporated in the mix in dry form mixed with the dry materiaLbut could be incorporated in other ways. w A

'I'hirdly, a type of high speed mec l agcal agit a: tion of the low viscosi y so e fluid mass 18 -empleyed which results in .a rapid formation of bubbles of a tenacious minutely fine stable character. We have found that high capacity high speedmixers withthin bladed boaters, suchas used in the commercial production of mayonbperation. When a light-weight end product, such as insulating brick having a fired weight as low as 1 lb. per ,101 cu. in. (standard fire brick size) is desired,- the water and dry materials may be blended, either by a-HBing the dry materials to the water or vice versa, so longras the desired attained, and a uniform high speed agitation employed Preferably however, the dry materials are added to the water in view of the more rapid and uniform dispersion of the solid'particles into-the 'water thereby obtainable; while maintaining a high uniform rate of agitation. The total time required under commercial batch capacities for blending and agitating such mixtures in themixing chamber and draining the foamed material into molds has been found to be less than one minute; The blending and foaming operations described are equally applicable for useinacontmuousproces's. v

.When a heavier and stronger desired'requiring a proportion-of dry materials to water such as would materialh -,reducethe "foamingcharacteristic ofthe :mass,-it=has been found preferable to :substantially decrease the rate of agitation during the latterpart of the agitation period when the fluidity is lowest in order to minimize, the escape of bubbles from the mix and thus avoid reduction of thepercentage of voids therein. With all types of mixtures,

and imam is however, it is desirable to produge cavitation at the surface of e the foaming operatidrltthat. end the multipfiblades tithe beater are so situated relative to the sur- 5 face of the mass that they are repeatedly being transferred from the air to the mass carrying down into the mass small quantities of air which later are divided up into smaller bubbles. It is usually desirable to have the beater blades .totally immersed in the latter part of the agitating period. In no case is the agitation continued for a period beyond that which permits the mixture to be molded prior to setting.

- An improved light-weight refractory insulating brick suitable for temperatures up to 2000 F. andhaving good load carrying propertie has been made in accordance with our invention by first mixing the dry ingredients in the following proportions:

misery mixture was; .then blended with water in'a ratio of partsof Water to 12' parts of dry material by weight. The fluid mass was then mefor 1 periods of from thirty secoffds to three minutes until the mass was impregnated with bubbles to an-extent that the fired products-were found to have a'aporositybetween 80-90% 'by. volume. Prior to-setting, the mixture was run off. into moldswhich were stripped as soon as the material was "set hard enough to'handle. "The wet molded shapes were then fired; in a s'uitable kiln.'- The brick ternper-ature wasraised in 1.5 hours to 'atemperature 40 of 2200 I' a'nd athen heldat that temperature or ours.'*-Thekiln was operated an oxidizing atmosphere through'out. The brieks produced varied -in weight from l-lf5 lbs. for

standard size, with athermal conductivity epgroxlzimately one-sixth that of first quality fire ric :1

An insulating brick of substantially similar properties was produced'with' the following for- The formula distinguishes from thepiior forinula by .th' addition of asfi u amolintpfpin sawdust, which per-mites more "rapid cycle t b l dy In'sulatinglbricks or similar .pioperftiesfwre e1 0 ,formedg wiiph an additional 20% of rajy Geor" 1a kaolin substitutedfor the grog n the first formula. Otherre fractory materials, such as magi; esite', chrome-or nma'may be usedin lieu of kaolin In all of these bricks the-bulk of the voids was very fine and of'pr'actically unir n spersion, and generally, globular inform. flf'hese yolds in the finished product are. surrounded by a net work of indurated foran'iinoiis partitions of the solid material which support'the structure while rendering it pe meable to asught degree, and hence adapt it'for sound as well as a. COMPOSlTlUNs,- I

comma o isnc plaster ofQPa ris by weight, ndecfianicallyagitatingthesamefor aperiod-ot from 30; seco nds i5,

' 'nnn' utes depending uponwater-temperature con- II na oa nt t iap r o a m i b e entrapped.- I In no casehowever islithe beatin f continuedso Ilongthatthere wouldpeinsufilclent.

I fatty alcohol sulphate capable'of rapidly wetting time; tqspreadl t'he'material -toalthieknesgjgn about 0f1arrinch on building paper before set- I $1.118 urs... -t'ses s e t of il r i anarere is. then ad;i e ,-.in-. the .usual' mannen Hair or.

other fibrg s r3 13 rial-maybe added t -the-rnigrture, loreagitation if desired, cwhenfset the materialiseutintosheetsof suitabl -sna I nvent n ut he foregoing e e t Will- H be,- fou'nd' advantageous. t .,use water at fairly, elevated-temperatures, that is to say from Iv to 186} R, as nsucE .combinatipnsof'ingredients. the-use bf wallll water has been found to allow the. use; of smaller quantities g; thgjoaming ggentg i thanwhermw 1Q( F. is.. used. on seduentlyforqthe same .amoi int of the foaming. agent wantmrm. watch the volume. of the e nl ree eamd e n a h ie time,

intervaL I While the. manufacture: of seve'ral products in. 5'

firing the molded-productswhile containing substantially all of the watermresent aftermolding to a relatively high temperature during a relaaccordancewith our intention has been described, it isneyerth'eless tohe understood that, I

in. practicing the invention We may resort, to. modifications in bothmethod and product so;. long as the same are within the scope'of the ap-' pended claims definingthe invention. I .1

Weclaimz-v I I I 1 I r 1. The method of manufacturing light-weight insulating brick of high porosity which comprises forminga solidifiable mass of relatively low viscosity containing argillaceous material, plaster of. Paris, water equal to at least 70% of thetotah weight of the pther constituents, and an alkylsulphuric acid. ester foaming. agent capable of rapidly wetting out the solid materialin the mass,

lowering the surface tension of the water, and 50 stable in the presence of alkaline compounds,-

mechanically agitating the-mass at a relatively high speed until the mass is foamed into a stable structure of substantially increased volume, molding the mass before setting, and firing the molded bodies.

2. The method of manufacturing light-weight 7 non-metallic structural material of high porosity which comprises mechanically agitating asolidifiable fluid mass of relatively low viscosity 0011- taining argillaceousmaterial, plaster of- Paris, water equal. to at least.70%- of the total weight of the other constituents, and a small amount of out the solid material in the mass, lowering the 65 surface tension of the water, and stable in the process of alkaline compounds, until the mass is I foamed into a stable structure of substantially l 7 Cross Reierence Pine sawdust I 3 bustible organic material, andanalkyl. sulphuric acid esterstable in the presence of alkaline-compounds, with an amount of water equal to at least .70% of the total. weight of theother constituents.

toform a solidifi'able mass of relatively low fviscosity; and mechanically agitating the mass at a',

relatively; high speed for a] period "shorter than.

the setting period of. the mass anduntil the mass is foamed into a stable structure of substantially increased volume, molding the foamed mass be fore :setting' .and 1 then firing to refractcrines's.

4; The method; or manufacturing insulating mixing operation; mechanically agitating the mass at-a relatively-high speedduring the mixing operation-until-the-massis foamed into a stablestructuresof-substantially increased volume, 'decreasing therate of agitation as the viscosity-of the mass increases, molding the mass before's'et tingyand thenfiring-the molded bodies. if a 1 5. The: method of making a light-weight in sulating .brickmfzhighfporosity which comprises blending, a. dry mixture of arglllaceo'us material; plaster of, Parisj'wood flour; and an alkyl sulnhuric acid ester foaming agent, with sufficient warm-watentnform a solidifiable mass of relativelyhigh'fluidity-while mechanically agitating!- I the" formingma s untila foamed stable structure of :substantially'; increased volume. is-formed,

molding the foamedmassbefore setting, and then tively short burning cycle.

I 6. A structural burned-ceramic product formed. by. burning a-molded foamed water mixture of -argillaceousmaterial. calcined gypsum and a laurylalcohol sulphate having after burning a.-

density less than 25 lbs. per cubic foot.

7. A burnt ceramic cellular product formed by burning a foamed molded mixture of the approximate proportionsr- I Raw Georgia kaolin Plaster of Paris Grog or grindings from pre-- viously burned brick of the same character Alkyl sulphuric acid ester;

% by weight. 30% by weight.

20% by Weight.

burnin afoamed' molded mixture ofthe approximate proportions;

Raw Georgia kaolin. 53% by weight.

Plaster of Paris 33% by weight. Grog or grindings from pre- I viously burned brick of the same character 9% by weight. 4% by weight,

I Alkyl sulphuric acid ester foaming agent a; of 1% by weight. Water I 10 parts to 12 parts I g of dry mix by weight.

0 law txam 9. Acellular unburned produot formed'liy settlnga foamed mixture of the approximate proportions: j 1 Plaster oiPrisg;14;3 pe ts't e hp'.

Alkyl sulphuric xa'zcid feste foaming egent w of 1 :159 weight v, V of the plaster fof l, ,Paris. water u n"; 10 parts by ei utg;

10,. The method ol' making a. light-weight insulating refrectorybrlck which comprises blending a dry mixture of argillaceous material, plaster of Paris, andan alkyl sulphuric acid ester foaming agent, with water-equel :to at least -70% of the total weight of the other-constituents to fifirl'ntaming substantially alhbf-the water-present during them'olding operation by'subjecti'ng the products to a relatively high tem erature. i

12. As a new artlcle'o'f manufacture, a 'burht ceramic; cellularproduct formed by burning a foamed molded shape formed from a mix'ture of di'y meteria'ls'inludmge. c'ei'amierefx actory material, 'plastef'fof Paris ehd finely divided combustlble br'ga'nic' matel'iL'L- the rehfactory materiel over' 5( and the hydrauliclsettlng agent being 0v"'e'r 20% by weight of the'dry material,

' a small amount ofen alkyl sulphurie acid ester while meohanicallyagltatm'g the mass 11mm foamed stablestriicture of substantially increased volume isformed, molding the foamed mass-be fore setting, and then sublectlngthe' molded pied ucts while containing substantially Ill-bribe water present'after molding to a. relatively-high temperature.

11. The method ormskin e-lluuweighmn-' sulating refractory briek'whieh coziipfl'se'sblend ing a dry mixtureof-er'gillaceous-materiaL'iblaster of Paris, a finely -v divided combustible oYganic material, and awsulphonated fatty-alcohol Ioam ing went, with water equal to atleastflfi'it of the total weight of the other oonstltueuts-to l'oi'm a solidiflable mass of relatively high-fluidity while mechanically-agitating the massuhtll'a foamed stable structure of substantially increased volume is formed,.molding thefoamed mass'befdfe set and thenfirin'g thfineldecfbroducts' set suficlently to permit heridlir' g and wh'llebbir foe'mihgegeut and wate' equal to 25.1; least 70% 61 the total weight of the other constituents. u

-13.','As"a'n ew article of manu acture, an in roamed gliuxture oi eeramie refractpry matei'iel,

a quifiksetulig enu-mots mdterial, sawdust,"

an aim sulphurio' agii t'ljester reaming Ei ent, and

.935 amount of waiter etiliel to over "50% the we! Weight the other eonstituents 6: the inixtire, 531d having uft er being fired 's'qellular box-bus stable ihdurated structure weighir 'gles's than 25 15s? pelfcubic fofi' a-r'i'd "a thermal -condueti 'vlty approximately one'siigth 1 at pf fii'st quality firebnck.

yeigh less than 25 lbs. per c'ubib' rm.

- emerge jL. hem-01s, .13.

seem: