US2451446A - Light-weight fiber containing product - Google Patents

Description

4indented Ocala 194s PATENT OFFICE LIGHT-WEIGHT FIBER CONTAINING PRODUCT 'Joseph R. Parsons, Chicago, Ill., assignor to United States Gypsum Company, Chicago, lll., a corporation of Illinois Application September 6, 1943, Serial No. 501,429

3 Claims.

The present invention relates to a process for the distribution of considerable quantities of finely divided fibrous material throughout a mass of either r ilnely comminuted material, (Q with a mass of sucl ma a w as et with a gtaggi fluid and then caused to ehardene or se One of the primary objects of the present invention concerns itself with the blending of relatively large quantities of fibers with a hardenable material such as a clay, cement, gypsum or the like, f'the dual pu''o'se o? dissi: u ng e said fibers therethrough, and also with a view to pr uc ng therefrom very light weight masses which do not exhibit any great tendency to slump either during drying, hardening, or firing. y

In other words, the present invention enables the production, from suitable materials, of extremely li ht weight products, which may be either organimoLiigganic, or may consist of a mixure of organic and morgan c materials. Exlcat ve o suc pro ucts are insulating blankets, insulating blocks, and sheets of organic material or of a mixture of organic or inorganic V materials, or of nnished boards or planks, and

emulsign with` fiber, either-"mtg or without se t or ardeni materials, w c will g '5'- extremel'y light in 4'wei'giit and which can be made with a minimum amount of iluid additions.

As a result of the practice of the present invention, the hitherto prolonged and expensive drying of the products is to a large extent obvi ated, or rendered very much less troublesome, by virtue of the fact that not so much initial moisture has been introduced as by the processes hitherto in'use.

The fundamental andv essential feature of the 'present invention resides in the discovery by the inventor that an emulsion, conijgainggmgaseous bubbles, may have distributed therethrouglfv evenly and uniformly, if desired, a large amount of brous or dry material, or both; and that the resulting mixture may be incorporated with large quantities of setting or hardenable materials under such conditions that the liber-emulsion mixture may become uniformly distributed through the large mass of setting or hardenable material. More specifically, the invention concerns itself with the manufacture of light weight insulating products made up of either a mentmgugg:

ffm -s (Cl. 10G- 88) 2 teria l@ non-setting material such as cla? or aoiin hici can 5e hardened by subsequen Eg, and a certain amount of fiber which, prior to the introduction thereof into'tlaseous emul- 5 sion, has been dried so that the ber will tend to absorb a considerable quantity of the liquid portions of the emulsion without, however, causing it to break. Consequently, the fibers are kept in a state of loose aggregation, the liber extend` ing in all three cubical dimensions, thus reinforcing the product and preventing it. from slumping or shrinking to any great extent during the drying operations.

For instance, a given amount of gauging V iluicl '15 o wa r may have added thereto certain her'- a ter more deinitely deilned surface-tension reducing agen? and colloidal material, wHereer s gaug ng fluid or water may whipped so as to incorporate therewith a large vo ume o 2g gaseous bubbles with the result that the initial vo ume o he liquid will -be greatly increased, for example, five-fold. 'I'hat is to say, starting, for instance, with 100 cubic centimeters of the emulsiiable material in the form of the liquid, this may, by suitable whipping, be converted into 500 cubic centimeters of a gaseous emulsion. It will be self-evident that there will be no increase in weight as` a result of such emulsiilcation. There will, however, result a very light weight gauging fluid which can be substituted almost volume for volume for an unemulsifled liquid.

Fibrous material may be blended with such an emulsionsowtat it will tend to become distribltdwabut and between the interfaces of the v gaseous bubbles and the liquid, thus. becoming oriented in all three cubical dimensions, but held `in position by the relative non-collapsibility of the said bubbles. This relative non-collapsibility of the bubbles can be secured by choosing suit- 40 able surface-tension reducing agents for the production o! tebiiles, ahsitable reinforcing colloids to prevent their collapse upon e a x "'tu-re-t'fl'rewith of the aforementioned mer-,ab-

sorptive fiber. After attaching themselves to e ers an filler particles, eventually the bubbles break, giving up their water which may be heid mechanically in the interstices of the bers or combined chemically therewith, producing hydrates.

Depending upon the proportions used, various light weight products can be made, among which may be mentioned the following: gypsum board,

ustica acoustical plaster, insulating products, gypsum insulating ties, nailable gypsum boards, nailable cement boards, ceramic insulat- 3 ing brick, light-weight ceramic products, asphalt insulating products, roo; insulation, insulating blankets, insulating tiles, packing materials, and ber boards.

The relative density of the material is completely under the control of the operator and may be nodied by the kind of materials used.

One of the important features of the present invention resides in the broad discovery that a gauging uid which has been rendered s ecicall llglf r, or EasT'" n reucel in ensity Ey the inr'duction thereinto of gaseous bubbles, will vbehave, volume for volume, about the same as a plain liquid. In other words, if, for instance, a certain type of calcined gypsum would have a consistency, let us say, of 63 cubic centimeters (which means that 100 grams of the calcined gypsum requires 63 cubic centimeters or grams of water to produce a iowable slurry), this can be converted into a light-weight slurry by the addition of a Bregenerateq gaseous emulsion weighing approxima e y 20 grams, or t e gh -weight slurry made by the conventional method would now have a consistency of 83 cubic centimeters. That is to say, 63 cubic centimeters are used to gauge the calcined gypsum, and 20 cubic centimeters form the foam solution. However, by my method a light-weight slurry which is moldable could be made using a total of 50 cubic centimeters of uid, if the dry calcined gypsum were added to a light-weight gaseous emulsion; that is to say, actually 30 cubic centimeters less of uid would be usedY in niv process as compared to the conventional method of producing a light-weight slurry. This is a rather surprising discovery, for ordinarily one would certainly believe that the admixture of so small a quantity by weight of water with so large a quantity of a dry, waterabsorbing material such as gypsum, would cause a complete collapse of all of the bubbles in the emulsion, with the production oi a dry crumbly mass.

As a matter of fact, however, it appears that in the present case the bubbles act as a sort of a solution lubricant, which enables this relatively small amount, by weight, of 'water to wet all of the gypsum. Now, if to such an emulsion of aseous'bubbles in water there be rst ded a mm brous materials, and these be then mixed with tgyu it 'wm be found that the ilbers will be cai'lto all portions of the resulting mixture, becoming very unii'ormly distributed therethrough. If such a mass is then dried, it will form an extremely light 55 weight product, primarily by the presence of the large amount of brous material which will be found in the product distributed in all three cubical dimensions. Thereafter, the bers will be cemented to each other at all their points of 30 mutual contact,v thus preserving the open. porous nature of the resulting product. l lThe more'specic aspect of the present invention will now be described in connection with certain practical examples which are illustrative 65 oi' the invention, but are not intended to limit the same:

More specincally, as when' producing light weight insulating materials, the process involves the production of a stawbgwem b ollowed by the pora onw sa em sion of ibi-ous materials, such as lulosicgr minmiam after 1v c there ism e'd e mixture thus obtained a vhardenable substance, such as cement, tw! 75 l 4 iaririaceous products and the n a minimum amount of liquid relative to the amount of fibrous material subsequently to be incorporated, wherebfter the addition of thelilbrous material, such for example as neous cellulosic bers,

e o er wo l e l rous material 20 is added to the emulsion s6 that the nbers wil-1 tend to orient themselves in the interfacial walls of the therein dispersed bubbles, whereafter, by proper mixing, they eventually become substantially uniformly distributed through the emulsion, forming therewith a homogeneous mixture. The iibers absorb some of the liquid -of the emulsion thus rendering it thicker and more stable. If one were to allow such a mixture to dry, the fibers would form a very loose state of aggregation which would lack, however, any great degree of cohesion unless the emulsion had contained some adhesive material. For some purposes such a product might be sufilcient, particularly where rigidity is not essential. However. in the manuiacture of commercial products, where rigidity, or at least a state of adherent aggregation, is

' desirable, it is necessary to add to the fiber-emulgaseous emulsion,depending upon the size and type of ber or other additive employed. This can be 4accomplished by len ggtgaini 1- agents or by ncreas ugd y l tion o su i sin solution.

Applicant has found that he can produce adherent aggregates of fibrous material which weigh less than one pound per cubic foot and may be varied up to 45 pounds per cubic foot, depending upon the setting materials used and somewhat also upon the nature of the materials from which the emulsion is originally produced and also of course upon the nature and other physical prop-V y erties of the fibrous material employed.

Generally speaking, applicant's products in their more advantageous commercial aspects are l u Q OHS y* sstanceszewhich solutions also contain sorie surace-nens on depant in the nature of a soa or- 'one'imahy present day available u wetti It has been found that an of Idislrsed air bupblesin a bo n arc with water and which solution may either contain or have incorporated therewith some wetting agent such as saponin, soa resin soa or thetic organic wem 'ag'f t, or a Blend of such mateials may Egrea'w prepared, thus incorporating a. large volume of stable bubbles vin the liquid by the process of whip' ping the latter, very much' on the order in whlchcream or white of eggs are whipped. The effect is of course the entrapment in the fluid o! myriads of' small air bubbles. In general, the liner the bubbles the more desirable is the emulsion for the purposes of the present invention.

The invention vis however not limited to an emulsion prepared by mechanical agitation or whipping, as the bubbles may be incorporated with the liquid by means of fore 1 streams oilair lsmhglg into the liquid; preferably a f y ma; 3.,.; t: nor y the expedient o having present in the liq d as initially formed a component of an active mixture, where afterwards a second component is incorporated, which by reaction with the first component will liberate bubbles. Examples of such mixtures wo for instance, a starch solution containing for example saponinmor some other wetting agent,

also some sodium bicarbonate, whe'fti" the liquid may mixed w h a uminum sulfate or with an a i which will react with me bicarbonate through t e formation of a salt and the simultaneous development of carbon dioxide bubbles. Other means for creating u les woul be to have the solution alkaline and to add, for example, metallc aluminum in finely powdered form, or else to develo'pi Bubbles in the starch and wetting agent solution by incorporating a gxasvdeg velgpinggchemlcal such' as calcium carbide `and the In other words, the method of forming the gas emulsion is of no particular essence and applicant reserves to himself the right to produce the emulsion used in his process by any or the above indicated methods.

The QQZS. 115,66. in connection with the present nventlon may be of a mineral nature such as i er l ol, glass wool, rock wool and the like, or theynay be Q rgm'i'c in nate such as wool,

ai I cotton, wo or other forms of cellulose, or mixtures 01 ffs. eitherarsssinsi? 0r combinations oi these. For commerialpupbses. however, it has been found that ground wood, and particularly the bers produce y "animer-mill grinding of old paper such as newspaper and magazines, pr a fibrous am parcu ar e ectiveness in connection with the presen t invention. It appears that the gas bubbles in the emulsion act as a sort of solution lubricant for the low lensity fiber employed, thus causing th'e spreading of the :liber individually throughout the entire emulsion structure. Moreover, the emulsion itself contains a relatively large volume of gas as compared with the volume occupied by the water, so that only the surfaces of the bers are dampened. This prevents any -undesired weakening of the iibers, and at the same time produces a much stronger structure than could be obtained were the mixture made by suspending the fibers in the liquid prior to producing the gaseous bubbles therein. At the same time', some of the liquid is abstracted from the foam, thus rendering it stiller and more stable. y

In the present method of operation, no excess of water is used, thus necessitating but a mllmum of drying, 4and allowing the'use of a. wide variety of fibers. Moreover, the resulting inter? laced ber structure is held intact so that it is not A to use suction to remove the excess water when forming the insulating materials into their desired shape.

The me or wetting agents employed variesvery widely an may co s of soa bark, rosin soaps other organic soaps or syntetlc wet' agents, or midx ures o these ma er s. v g-rea many of these are now available under various trade names, and are very well known inthe art. It should be noticed that in the present invention, after the gaseous emulsion has rst been prepared, the fibers are added dry, whereafter the 1 setting material is also added in the dry form.

' called The dry addition of the bers helps to absorb water from the gas emulsion.

As' specific examples of the production of various types of insulating materials, the following may be cited:

' Example I In this example the object is to prepare iVBitim/gteriaun the form of acoustical tile.

obviously also will inherently have heat-insuiatlng as well as sound-insulating properties. A dried product weighing about 24 pounds per cubic foot may be prepared by employing about cubic centimeters oi' a 2% ggution of a sothin-bodlln starch. This so ut on .prepared Bysuspening say 20 grams of the raw starch in 1000 cubic centimeters of water, and then bringing this mixture to the gelatinizing point of the starch, which is slightly below the boiling point of the water. To the s trllmsolution thus obtained, which is a fairly uid liiid;

But having a greater viscosity than water, there solution thus produced is violentlyiggguntil all of the liquid has been converte n o ascontaining emulsion and practically no liquid` tree of BuBBles remains. In other words, substantially the entire 1000 cubic centimeters of solution are converted into an emulsion. This will occupy a space from four to ilve times as great as that of the initial solution. There are then added, separately or in admfixture, the following amounts of iibr n ia to-wit, 50 grams 0f dry and 10 mms of d sulte paper ul' ground in a hammermili. THe incorporation of the emulsion and 4the fiber is accomplished by means of a commercial mixer which gradually folds the emulsion over and over as the liber is added so that a thorough incorporation of the fiber and the emulsion is obtained. As an alternative, a commercial mixing machine on the principle of an egg beater, preferably with a. revolving tank or bucket, may also be employed. In any event, the grams of liber are thoroughly incorporated with the emulsion until a substantially uniform mixture is obtained. Thereafter there are gradually sifted into the mixture about 850 grams of calcined sum. For this purpose applicant pife-rs-t use that particular 4type of low consistency gypsum which has become known in the industry under the general designation of alpha g um, and which is more fully described ln-t'e patent -to Rande] and Dailey No. 1,901,051.

There is also added, preferably in admixtureA with the alpha" gypsum, about l5 grams of an agzeierator such as terra alba. 'I'his terra alba. in the present case, r'Te e'rs to a finely ground nanecessary, as has been the case with the prior art, -75 ural gypsum, which is calcium sulfate vdihydra 7 The setting of the gypsum gives eventual stability to the product being made. However, before the gypsum has a chance to set, the mixture is formed into the desired shapes, such as plates, sheets or blocks, which can be accomplished by pouring the mixture into suitable molds which may be made of wood, metal, rubber, plastics or the like. It is possible-under these conditions to produce also various surface characteristics in the finished product and to give it the appearance of articial stone such for example as travertine. This may be done by providing the face of the mold with irregularly shaped particles of a resilient material such as rubber, hardened walter-insoluble gelatin. and the like, or with an ornamental shape. This technique-is well known in the stucco molding art. v.It will be noted that no attempt is made to remove water physically from the mixture. In other words, the 1000 parts of water which have been used to produce the emulsion are absorbed to a considerable extent by the 150 grams of ber and the 850 grams of the calcined gypsum. so that the entire mass,

upon the setting of the gypsum, solidies into a solid, which is very light in weight, weighing only about 24 to 30 pounds per cubic foot, after drying. .Af-ter setting has taken place, the product may be liberated from the mold anei allowed to dry either at room temperatur l or t slightv ppn-1 ra urs'," n even AIt will be self-evident that colorin matters may be added if desired to give the pruct a desired shade or tint.

Example II The invention may also be employed for the production of a very light weight wallboard having a gypsum core and covered by two sheets of heavy paper. In itself the manufacture of wallboard -is not new, and the present invention therefore relates only to such portion of the making of a gypsum wallboard as involves the preparation of the core material now to be described. 'I'his core material, prior to the setting .of the gypsum, is placed between two simultaneously advancing sheets of cover paper and allowed to set therebetween. This may be accomplished by means of the well known machines for the manufacture of gypsum -wallboax-d.

In order to illustrate the present phaseof the invention, there is submitted herewith a single sheet of drawings in which the gure is a cross section, on a greatly enlarged and exaggerated scale, of gypsum wallboard made in accordance with the present invention.

To prepare the core material one may proceed asfo'llows: 90 grams of a'thin-boiling-h are suspended in 1500 cubic ,centimeters of vgahas been hammermground as described in Example I. This nbrous mixture, that is, a total of 250 grams, is thor- 'ously blended with me emuisgnn, ma thereafter .T5

there is then added thereto '750 grams of ordinary calcinedggypsum, that is to say, calciumxciiv sulfate dneil,iysgrateg or, as it is also calle'dzmmstucco.. This may contain 25 grams of mmra v n the form of terra alba, as mentioned in connection with Example I.

After the gypsum and accelerator have been thoroughly incorporated with the emulsion, which may be accomplished in the space of a. few seconds, and which is preferably done in the present case just prior to the placing of -the core mixture between the brous cover sheets 2. 'the mixture is so placed and the process of making the wallboard continued in the usual fashion. After setting and drying, this will result in a wallboard which, for a thickness of 5", will weigh only vabout 600 pounds per 1000 square feet. The core 3 .containing the fibers and set gypsum is also shown in the drawing.

If the density of this material is calculated on the basis of pounds per cubic foot, it will be found to fall somewhere within the limits between 12 and 20 pounds. As compared with the wallboard cores previously made, this is exceedingly much lighter, as most of the so-called light-weight wallboards have weighed anywhere from 1400 to 1800 pounds per 1000 square feet, even on the basis. No wallboard of equivalent light weight has hitherto been proposed or described, and it n is one 'of the outstanding advantages of applicants invention to prepare such a light-weight wallboard and the like.

Example III bark, and the mixture stirred until the 'Soap ai' een completely dissolved. The mixtureis as then gaten until, by the incorporation of a sufncien am of air bubbles, a total volume of about four to six timel"original volume has been obtained.

It will be noticed that in this case the concentration of the primary starch solution is .somewhat greater as to its starch content and there- 4fore produces a thicker and even more stable emulsion. To the emulsion thus made there are added '120 grams of dg newspapgr which has been disintegratedorground in a hammermill. A-t the same 'time there are also incorporated 50 grams of a commercial as hal lulsion.

After the starch-'ges emulsion, ber, and `the asphalt emulsion have been blended so as to producea homogeneous mixture, .there are then rapidly added 180 grams of calcinedwgypsym, in this case preferably the alpha gypsumalrea'dy hereinabove fully descr'ib'flhismixture is then molded into shape, producing for instance bats from to 4" in thickness, depending upon the desire of the manufacturer; the mixture so made forming a ba-t which is suiliciently coherent'to permit handling without the necessity of using cover sheets thereon. However, it should be considered as within applican-ts invention to cover either 'one or both sides of these bats with paper cover sheets, and perhapsan impervious asphalted sheet on one side, and `a relatively thin-and perforated sheet of paper on the other. The bats Y mentioned, only a temporary set of the mass thus produced will have a density of as low as 4 occurs, but nal hardness is attained Iby poun-dsper cubic foot, and w-ill not support com- 1 M itable ceramic-ming temperature. bastion. They are nevertheless suiliciently selflar 'Wvbiswtlwisuch as coherent so as not to shrink or slump in drying. mineral wl, asbestos, or high-melting lass wool- This is the result of theI relatively small amount beenised-at? fibrous material, e rs of water used and therefore differentiates the will be burnt away, thus still further increasing present invention from what has preceded it. the porosity of the material.v

. The importanceof adding 4the l- Emmplev Y i I ggggggrgnust notbe overlooked. o,t irs l0 should preferably, but not necessarily, be er a A 4liant-weight insulating blanket, having coq- Vll uid-'absorbin nature so that as much sa possiderable rigidity, can be prepared in accordance sle of the lqid poion of the emulsion will with the following formula:

be absorbed, or adsorbed, by the bers. The ef- Parts by weight fect of this is greatly to stiflen the emulsion. The 1 Loosev mineral wool 165 stabilizing film surrounding the individual dis- Kraft ber (cellulosic) persed air or gas bubbles will, however, not be Soap bark v 3 destroyed', as there w-be a certain amount of Binder solution, containing 2% of thick-boilconcentration of the dissolved solidsof the emuling. and 1% of thin-boiling cooked sion. due to the liquid-absorption or adsorption 2 starches v d 425 of the fibers. Hence the bubbles will remain as 16% paraiiin suspension 25 globular aggregates that help to sustain the bers -In mducing this maten a1 the soa bark ifs djs* in their heterogeneous orientation in all three perged in the 425 parts of the bllder solution, cublcal dimensions, which counteracts slumping md the mixture is entirely converted into a gas of the mixture. If a'setting substance be pres- 25 emulsion Weighing about 4 pounds percubic ma?. ent, this, on setting, will then permanentlyx the mr the dry, bers l eral wool and: position of au the nd ingredients' As the free kraft) are slowly added; whereupon the wax susliquid disappears, either by combination with-the pension is added and the mixing conn n-mm2d for setting substance or by evaporation, or both, the `mime to insure uniformity. The .resulting interior space of the bubbles merges with the at- 30 mixture is then placed mbo m01 ds and allowed to mosphere. thus leaving the prgduct highly conharden therein afterwards. being dried. u de; nectedly porous, as distinguis ed from uncon' sired, the above material can be colorggbfor ex- .nected cellularlty. Thus while the bubbles form ample. a pmkish red by the Wpomtmn of :A ,f an aggregate during the formation of the mass about 4 parts by. weight of .imnxidg The te;

2f material they ummgtely disappear 35 sultingbats may, if desired, ere with cover Y Example IV sheets of yany desired kind.

Another ty-pe of light weight incombustible in- Example VI' sulating blanket o r bat may be made as follows: Under Some circumstances it may be desirable with 425 grams 0232@ containing 3% or 40 to have a non-uniform distribution of @bers in starch, 2% of powder `soap bark and 25 grams ...s e ma ....l,... M or a wax starch us ension all of which has been nog mixture' Th canwbe accompsherby Sing agitated until, by the incorporation of finely dl- .w

vi'dd' air bubbles it produces a volume eight to 55E-s Th E- e individual nodules, while they will .be-

ten times t e original volume I incorporate 35 45 come distributed in the bubbly mixture, will not rams o finel divided cellulose fibers, for in. MU `finance lrf bers and 165 grams of mineral rlgrdtif: xsi 1 Tg'lep Ilsberl' Tiggaggeeunsnn ture is concerned. As to relative quantities and )UCI slred thickness, up to practical limits of better 5o mode of operationExampl? Visagmde than 8 inches in height, either in separate units Example VII or in a continuous ribbon, thus forming a blanket A nght weight resilient insulating blanket may or hat of any desired width be produced from a aseou l sion of d The material then is dried and may be Cut t0 b 1o an size or shape suitable as rilock, bat or blanket m confiance with e fol ihsgi''ibnlr'cushioning material. The product thus produced may be made to have a density as Y COmmOn Wmbe (N17) Soap "grams" 8 low as one pound per cubic foot and possess inter N1 cm..- 250 herent halatelistics 0f resiliency and toughness This mixture is beaten into a gaseous emulsion wmen will permit it to be used and handled for so umu mest er th'mvater has disappeared. ordinary insulation purposes. While it is desir- There are then added able for some purposes to incorporate cellulosic 1j-mr, such espigas-.g or similar fibers, inderto pulp (dry) "grams-- 10 impart toughness 4to the resilient product, neverd add the pulp uniformly dispersed mm the gaseous theless, Very tisfacltly 111511115121118 afgis-1S 05 emulsion; whereupon there are added may be produc simp y us g inorg c rs, such as mineral wool, glass Wool, etc., Without the (ubber emulsion "gr 50 Y ol, or so-called gcranulated mineral t e nodules being -adde to t e gas emuladdition of any other liber. nd the mixture l or a short time to mak I also may incorporate other water roon it homogeneous. t hen molded without dlagents in the emulsion, which increase the water 70 tration and allowed to dry. resistance of the finished product. Stearates, g, The rubber emulsion itself contains about thetic resins 'of various types, rubbeglatte;w or ru of solids consisting of recla o bber dissolved rect ma' used. amoun o sodi bilde. Such emulsions;

In the case of clayv products as hereinabove of rubber are weown articles oi.' commerce. "f 4 o L n V l r' t y r o s the mixture dries, the rubber emulsion breaks and the particles of rubber serve as a cemen-ting agent to aillx the paper ilbers to each other at 'their points of contact.

The .present invention is of broad applicability, and is only to be limited in scope by the claims appearing below. Obvious modiiications of the invention and its applicability to the production of insulating structures of more complicated shape are of course to be considered within the scope oi' the invention. Furthermore, other cementitious materials such as fast setting cements, as for instance those of tha"Portland`cement type. or the use of other setting mariais, such as Sorrel ements, may be employed. In fact, any organic su tance which will readily mix with' the water present is to be considered as encompsed within the purview oi the invention. Moreover, the of other glgyable adhesive material., such asv@ lim e ers or example, met celluloseLpglyving] aco ol, casein, vegetab e .gro-min, 'wa er-sol s such as gum 1c. tragacanEEw. etc., are also to be considered as wimope oi the invention.

From the foregoing examples it will be selievident that a broad invention has been disclosed. However, in order to preserve a line of division between heavy products and light products, applicant has claimed the production oi' relatively heavy products, such as are devoid of ber, in

his co-pending application, Serial No. 501,428, illed of even date herewith.

Applicant claims:

v1. Process of producing semi-rigid insulating bats which comprises preparing a solution of a iarinaceous material and a surface-tension reducing agent in water, incorporating a large numresulting mixture .with an asphalt emulsion and with dry calcine'd gypsum, forming the nal mixture thus produced into the desired shape without the application of substantial pressure thereto. and drying the thus shaped product.

f 2. Process of producing light-weight porous inllulating material which comprises whipping an aqueous starch solution containing a surface tehsion depressant into a stiff gaseous emulsion, stirring dry water-absorbent bers into said emulsion, and distributing them therein, thereupon adding and thoroughly admixing dry powdered calcined gypsum with the thus prepared nbered emulsion, forming the resul-ting mixture into a predetermined shape, causing it to set up as the result of the hydration of said calcined gypsum, and drying the product thus obtained.

3. Process of producing light-weight porous insulating material which comprises the steps of preparing a solution of a water-soluble colloidal 'organic bonding agent and a surface tension reducing agent in water, incorporating with said solution a large number of small individual bubbles so as to form an emulsion, incorporating dry water-insoluble fibers with the emulsion thus produced, and then adding dry calcined gypsum to the resulting mixture and shaping the ilnal mixture into shape substantially without the application of pressure thereto, permitting said gypsum to set, and eventually removing any residual water by evaporation thereof.

JOSEPH R. PARSONS. f

REFERENCES CITED The following references are of record in the file of this patent: Y

UNITED STATES PATENTS Great Britain s -...r- 1941 y

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