Document M4kM2QaGLvvwO81md5zOR41p9

FILE NAME: Keene (KNE) DATE: 1953 Mar 31 DOC#: KNE004 DOCUMENT DESCRIPTION: US Patent - Insulating Material Patented Mar. 31 1953 2,633,433 r re. UNITED STATES PATENT OFFICE Z.632,423 INSULATING MATERIAL Frederic* H. Hoflenfecrg, J r , VtyndmGor. Pa-, - sie n o r to E ild w in -H iB Com pany, T re n to n , -V J , ^ corporation of New Jersey * - No Brawno?. Application May Z, 1946, Serial No. 666^0" . ' 11 Claims. (CL 111--126) . The present invention relates to an inorganic m ter section end the resin nny even be sub stantially confined to the outer sections. bre insulating material of unusual and un The product may be precared by any process proved properties, and to a wet process pr0" in which a thermosetting resin and bentonite in during the same, and more particularly n 6 the presence of an aqueous medium is luccr- relates to an Insulating sheet material wmch is porated in inorganic fimous material, the fibres characterised by its fire-resistance. In addition, of which are interfelted in an aqueous suspension the invention relates ~o an aqueous resmous com thereof and in which the resin after its associa position which is available for use in the produc tion in the interfelted web is converted by heat tion c i inorganic fibrous Insulating material pcs- 10 to the infusible, insoluble stage. Since the ben water- and fire-resstnnt properties. tonite is incorporated in the inorganic hbroi One object of this invention is to provide an material in the presence of an aqueous mecium. inorganic fibre insulating material, which, while the water will swell the bentonite and the una, relatively light, possesses high flexural strength, product will contain bentonite in its swollen is waterproof, fireproof, and has high electrical 15 stare. ^ and thermal insulating values. In the preferred embodiment of the invention, Another object is to furnish an insulating ma the sheet of insulating material which is sub terial which possesses, in addition to other desir- jected to heat to convert the resin is formes &bl properties, Hre-resist3Xi.ce snd ii from an aqueous suspension of the fiorous ma- raised a t one portion to the combustion tem 20 terial by the use of a screen to remove water perature of the resin, will provide a barrier pre therefrom. Preferably, the thermosetting resin venting propagation of thermal cecomposmon in fijid bentonite. a.re mixed. "sritii tbe sus adjacent portions of tbe product. pension of the inorganic fibres, for example, in A further object is to provide an insulating the beater or the mixing cr agitating tank or the material comprising inorganic fibrous material, 23 head box, but if desired a soluble liquid resin a synthetic resin binder, 2n d bentonite, the latter * and the bentonite may be added to the inter ingredient imparting fire-resistance and other felted web, for example, to the wet fibre on the desirable properties to the product and wmea .sheet-producing screen or subsequently. If de product may be made by an economical and sired, instead of forming the interfelted web iicm commercially practical process. nn aqueous suspension by the use of a screen, a Still another object of the invention is to pro SO smaller amount of water may be employed and vide an insulating material in the production of tire resulting suspension may then be deposited which various types of thermosetting resins, in either continuous!;' cn a conveying system or cluding a soluble resin even in a very dilute solu batch-wise into forms. As will hereinafter ap tion, ma7 be used and in which the white wa.er pear, other additives, such as a supplemental may be utilized to make up new stock solutions. 35 fire-retardant, a de-foaming agent, a bentonite- StOl another coject is to provide a resinous viscosity reducing agent or both may advanta composition comprising a soluble thermnse.tmg geously be added at a suitable point in the process. resin in solution in an aqueous medium and a By inorganic fibres is meant what is generally fire-retardant in suspension therein, which com known in the industry as glass wool, mineral position is available for use in the production of 40 (rock or slag) wool, and asbestos fibres and all inti.bHnc material of improved properties. these will be referred to generally herein as fit-res. Other objects win be apparent from a con sideration of thi3 specification and the claims. Any one of these fibrous materials may be used advantageously in the process, the use of mineral The insulating material of the present in wool being generally preferred, and mixtures of vention comprises an ii.terfelted web of inor 4a any two or all of them In varying proportions ganic fibrous material and a synthetic resin in may be utilised. For example, portions of long- its insoluble, infusible stage and bentonite in corporated in said interfelted web, the resin and fibre asbestos, such as amosite, may be advantageo'isly mixed with glass wool or rock wool or bentonite providing water-resistance and firs- both, to provide additional strength to the resistance, respectively, to the pr.-duct as wid 60 finished board. hereinafter be discussed. In one preferred embediment, the resin and bentonite are distributee In the case ci the use- of the glass or rock throughout the interfelted web substantially wool either long-fibre or loose wool, or what is known in the trade as granulated or nodulized uniform ly, but, if desired, the product may have ''ri irTi'+iCT -X --- 2,638,433 3 wool is prepared by nodufcring the wool an a rotary screen which also removes the major por tion of the shot, th at is the glass-like granules 4 bcsikm. It can be seen, therefore, th a t if any portion of the binder is raised to the combustion temperature of the resin, thermal decomposition of non-fiberized m aterial When long-fibre wool vein spread throughout the entire product unless is used, a large percentage of the slo t is ad some means is provided to prevent such action. vantageously removed in the process, icr ex The presence of the bentonite in the finished ample, by a riffie bos. The removal of the major product serves as the means for preventing the portion of the shot is Important since, obviously, propagation of thermal decomposition through substantial quantities of it will seriously alter the the product. Bentonite acts as an excellent fire- weight of the finished board without changing 10 retardant for all the various types of thermo the volume appreciably. setting resins that may be used in the production In the preferred embodiment of the invention, of the insulating material since the bentonite granulated or nodulized wool is employed since provides a mechanical barrier between the portion the finished product will have lower thermal con of the prodnet which has been raised to the com ductivity, lower density, greater strength, cud 15 bustion point of the resin and the adjacent por better handling properties, as compared to a tions. In the event the product is subjected to produet made from long-fibered wooL Mixtures a temperature sufficiently high to cause fusion of of long-fibered and nodulized wool may be used the bentonite, the fused bentonite then serves as if desired. the barrier. This condition occurs during the By "thermosetting resin" is meant any syn 20 application of the insulating material to a metal thetic resin in an initial stage of polymerization surface by metal pins, since in such a process the which is convertible by heat to the insoluble, in pins are arc-welded to the metal surface. Thus, fusible state. Such resins may be used in any if the material is ignited a t one portion, the com one of the three following forms: (1) as an aque bustion will not spread to other portions due to ous solution of a water-soluble liquid thermo 25 the barrier provided by the bentonite. setting resin; (2) as an aqueous emulsion of a The bentonite is used, in any particular case, water-insoluble thermosetting resin in liquid in an amount to provide the desired fire-resist form; and C?) as an aqueous dispersion of a ance to the product The amount employed will water-insoluble thermosetting resin in a dry be dependent on the quantity of resin in the powdered finely divided form. Mixtures thereof 30 product When optimum fire-resistance is de may also be used, if desired. The first two forms sired, the amount of bentonite will usually exceed contain liquid resins as distinguished from the the resin content; for example, with a product powdered resin o the third form. While any of the thermosetting resins, or mix containing 5% resin, about S% bentonite msy be present, whereas with a resin content of 3%, the tures thereof, may be employed, for example, phenol-formaldehyde, resorcinol-formaldehyde, bentonite content may only be about 5%. As previously stated, if desired, the fire- urea-formaldehyde, and furfural-formaldehyde, retardant characteristics of the bentemte may the use of a phenol-formaldehyde resin, that is be supplemented by the presence in the product a resin produced by reacting a phenol with a of another fire-retardant. While various chemi formaldehyde-yielding substance, is preferred. 40 cals having fire-retardant properties may be used Examples of the phenols are phenol, cresol, and with the bentonite, zinc ammonium phosphate xyleuol; and examples of formaldehyde-yielding has been found to be particularly effective. The substances are formaldehyde, paraformaldehyde, choice of the particular supplemental fire-retard and hexamethyl;etetramine. The usual ex ant employed will depend upon its ability to be tisenadetrhseorrmmopoldaisfiteicrs, shuycdhroacsa"rVboinns-oinl sroesluinb,l"e wrheiscihn 45 uwsietdh itnhethreedprro. ceasnsd wtoithboeutruentadienseidrabinle trheeactfiionn derived from pine-wood, containing phenol, alde ished material. Certain substances having fire- hyde and ether groups; "Liresinate," which is retardant properties are net available for use due merely an emulsion of the above described Vinsol to their reactivity with the resin, for example, rtheseinresininowuastceor,mapnodsittihone. like may be included in 50 nbiuntenbeotrwatiethmthaye lbiequuidserdeswinithduae tpoowitsderreeadctrivesitiyn Bentonite is a generic term covering colloidal with the latter. clays th at have an affinity for water and swell The proportions of inorganic fibre, resin, and in the presence thereof, and any of the various bentonite in the finished product may vary widely grades of bentonite, such as sodium-, potassium-, 55 but since these three ingredients are associated in calcium-, or magnesium-containing bentonites the presence of water, the relative amounts may be used in the production of the product of thereof will depend upca the particular type of the invention. Advantageously, a bentonite with process used in the preparation of the product a high water-absorptive capacity is employed and. Generally, the finished material will contain from pasrodstuactet di,n thae sbweonllteonnitsetawtei.ll Rbeegparredsleesnst oinf tthhee 60 aabboouutt 515%% ttoo aabboouutt 9370%% ooffintohregahneiact-fcibornev, efrrotemd type of resin employed, the presence of bentonite, resin, and from about 2% to about 25% of ben either alone or with ether fire retardants in the tonite. Insulating material having`particularly finished Insulating material serves to render the advantageous properties may contain from about product fire-resistant. 65 70% to about 97% of inorganic fibre, from about The resins used in this process, being of a com 1 % to about 10% of the heat-converted resin, and bustible nature, will undergo tbenn&i decomposi from about 2 , to about 13% of bentonite, for in tion when subjected to high temperatures, even stance. from 35% to 90% fibre, 4% to 6 % resin, when the resin Li incorporated with the inorganic and 6% to 3% bentonite. In a typical example, fibrous material in the finished product. The in 70 the insulating material contains 87% rock wool organic fibres in. the finished product form an fibre, 5% of a phenol-formaldehyde rosin con insulating blanket over the resin particles pre verted to its Infusible, insoluble state, and 8% of venting the heat of combustion from being dissi bentonite; in another example, the finished prod pated, and, due ".o the presence of the fibres, sir uct contained 22% of rock wool fiore. 3% cf a , - 1'i 1rw.v , - ' . \ Vt.u V. . K . v.v ... n*'i, -*, 1' *. .-.ijwcttvcrt.-vr phcnci-.fonrVsidebydi' rssfti, afitf -a,e3S,488 5 H ' 5% of bentonite. When a supplemental fire- tanite particles in suspension and 5% by weight retardant Is included In the product, the amount of resin solids in solution, after dfluticn with the thereof may vary from a very email amount, for water employed in the process, is desired, it is not example, a few tenths of a per cent up to 5% necessary to use an Initial resin solution having a or even more, based on the weight of the resin, 5 dflutability of a t least 14 to 1, but a solution of a and the amount employed in any particular case dilnt&bility ratio of less than 14 to 1 may be em . will be determined by the degree of supplemental ployed provided the dflutability ratio is greater "fire-retarding action desired. than about 4 to i. Thus, the bentonite will serve The insulating material of the present inven to convert a resin-precipitatable solution into & tion is characterized not only by fire-resistance 10 non-resia-precipicatable solution. ' .and wster-proofness, but also by high electrical It is to be understood that the resin content of and thermal insulation values. It is further the solution or suspension after the dilution by characterized by high flexural strength, sound the water in the process may vary widely, for absorbing properties, and resistance to Vibration- example, from about 1&% to about 20% by Referring to water-resistance, a sample of the 15 weight of resin solids, and that an initial resin insulating material of the invention was found solution to provide such resin content will be ' to have absorbed less than 6 % water in an atmos employed. This is also the case when a ream phere of 95% relative humidity at a temperature of 120* P. Even when the material was sub emulsion or dispersion is used. Likewise, the bentonite content of the resin- merged in cold, hot, or boiling water, it did not 20 water medium after the dilution by the water in deteriorate and after the wet insulating material the process may vary widely, for example, from was dried, the original strength was retatned. Tests of the product by the Columbia time-tem about 1% to IS% by weight of bentonite, and an initial amount of bentonite to provide such quan perature method, showed no evidence of burning. tity will be employed. The bentonite is prefer Furthermore, the product is characterized by its 25 ably moistened with sufficient water to swell it ease of handling and may be utilized with a before it is incorporated with the resin-water minimum of dusting and breakage and, there medium. When bentonite is employed in the fore, with practically no industrial health hazard. The product may, therefore, be used in any appli cation where such properties are desirable. The weight per cubic foot of the product may vary over a wide range, depending upon the proc ess steps employed in its production, as will here inafter be described, and usually the weight per upper portion of the range, for example, about o% and above, the viscosity of the medium is high 30 and, with relatively thick products, difficulty may be encountered in removing excess liquid from the interielted web when a screen is used in the formation thereof. In order to decrease the vis cosity of the medium, particularly when more cubic foot will be between about 6 and 25 pounds. 35 than about 6 % bentonite is present, it has been When the product is to be used as an insulating found that this may be accomplished by the in material for ships or in other applications where light weight product is desired, the weight per cubic foot is advantageously between about 6 and 10 pounds. As previously stated, various processes may be used in the preparation of the product, and the particular process depends on whether an aque ous solution, an emulsion, or a dispersion is initially employed. Furthermore, when an aque ous solution is employed, the process depends on whether the resin will remain In solution when the solution is brought into contact with the water employed in the process or whether the resin will precipitate under such conditions. These two types of initial aqueous solutions are termed "non- resin-precipitatable" and -``resinprecipitatable," respectively. When bentonite is include,! in the aqueous solution of the resin, the diiuiabllity of the solution without precipitation of the resin is markedly increased, so that a solu tion which Is normally resin-precipitatable may become upon the inclusion cl the bentonite the non-resin-precipitatable type. In a typical ease where it is desired to employ a non-rcsin-precipitatable solution and to pro vide a solution, after dilution with the water em ployed in the process, of 5% by weight of resin trVjiri*, an initial solution containing 70% resin solids and having a dfiutahility of at least 14 -(water) to 1 (solution) by weight Is employed. In a typical case where it is desired to employ a resin-precipita table solution and to provide a suspension containing 5% by weight of precipi tated resin solids after dilution with the water employed hi the process, an initial solution con taining 70% resin solids and having a dihstability of less than 14 (water) to 1 (solution) by Weight rt? need. Illustrative of the effect of bentonite, if a .spiution containing 5% to 10% by weight of ben- clusion in the resin-water medium of a small amount of a soluble polyphosphate; for example, sodium or potassium hexametaphosphate, tetra 40 phosphate, or pyrophosphate, sodium tetraphos phate being preferably employed. When a soluble polyphosphate is employed, some of it at least will be present in the finished heat-con verted product. The amount employed may vary 45 bfraosmedaofnewthteenwtheisgohft aofpetrhecebnet,ntuopnitote.3%Tohremporere ferred range 1s from about 0.5% to about 1.5%. Thus, in a typical case, where an 8% suspension .of bentonite (after dilution by the water in the 50 pprhoacteessw) aws apsreusseendt,, athned v1i%scoosfitysowdiausmretdeutrcaepdhaops proximately to that of a . 5% bentonite concen tration. In the case where the suspension of fibre, bentonite, and resin is sufficiently concen 55 trated so that It is not necessary to remove excess water by a screen, the use of a polyphosphate is usually not required since a high vis-rosity is an advantage. The process is preferably carried out by mix 60 oinrgganthice friebsrionusanmdattehreialbebnetfoonreitethwe itihntethrfeeltiend web is formed, and in this type of process, the non-resin-precipitating solution, the resin emul sion or resin dispersion may 1 added to the 65 beater, mixing, or agitating tank or head or de livery box to the screen used to form the web. If desired, instead of using a screen to form the web, a conveyor or stationary form may be em ployed. In this case, the use of granulated 70 mineral wool is advantageous. In the case a non-resin-precipltating solution, a resin-precipitating solution, or a resin emulsion .is used, the interfelted web after its formation, for instance, on the web-forming screen or after 75 removal therefrom either before or .after drying : 8,838,433 '" ' 3! ' 8 3*T be treated with an aqueous con- -the wet interielted web is placed upon, pallets -t&intag the resin and bentonite. Since the web which support it ha a fiat form and are designed la formed from a water-suspension of the inor to impart to the web a smooth fiat surface. The ganic fibrous material, it is a "water-laid web," pallets are placed on cars and Use cars in turn and as Is usual in water-laid webs the major por- z are placed in a drying tunnel. The drying tunnel ticn. of the fibers therein are oriented in a plane is usually kept at a temperature of between 250* substantially parallel to the plane of the web or F. and 550* F , a preferred range being between sheet. If the dried sheet is treated, it may or 300" F. to 350' F. At this temperature, the water may not be re-wet prior to the application of the is evaporated and the resin is converted to the resin-carrying medium, but, of course, it a pre- jo infusible, insoluble state. The length of !iw of dpitated resin is desired, the product must eon- heat-treatment is a function of the temperature tain sufficient water to cause a precipitation oi employed and usually requires three hours or the resin when a resin-precipitatable solution is more. employed. Furthermore, if desired, instead oi When the interielted web contains a resin treating the interielted web with an aqueous 55 which is soluble in the residual water associated medium containing both the resin and the bentonite, the bentonite may be incorporated with the web, there is a tendency during the dry ing cycle for such resin to migrate to the outer with the fibres prior to the interielting step or surface. This migration results in a product that subsequently thereto and after drying, the prod has a strong outer crust but a softer inner core. uct may be treated with an aqueous solution or emulsion, for example, by spraying, dipping, or ~ While such a product is a t times desirable, the passing the solution or emulsion through the use of bentonite has the further advantage, when product. a product having a substantially uniform distri When a resin-precipitatable solution is ap bution of resin is desired, since when using such plied to the interielted web, whether it be on soluble resin, the bentonite reduces the amount of the forming device or subsequently, the water " migration so that from a practical standpoint associated with the web and the displaced water very little occurs, although there usually is a is drawn through the web as filtrate. Sines the slight increase in resin concentration on the presence of the water in the web raises the outer surface. This slight increase is beneficial amount of water in the resin solution above the , 0 since it ties in the particles of fibre very com critical dilution ratio, the resin is precipitated pletely and provides a finished product which is from the solution and is dispersed throughout easier to handle. In fact, in cams where the the wet web. product has been cut to size before conversion of The interielted web of inorganic fibrous mate the resin, then the slight migration provides a rial, whether the resin be associated with the ^_ product in which the surfaces thereof including fibres prior to the formation of the web or there 35 the edges and ends are neatly sealed. after, is advantageously formed on the screen of Regardless 0/ the particular form of aqueous an Oliver filter or other type of revolving screen resin medium employed, it will be desirable to equipped with vacuum compartments,.but. if de sired, the web may be formed on the usual recirculate the water removed through the screen. This is particularly important when a cylinder type of paper machine or on the screen 0 non-resin-precipitating solution is employed of a Fourdrinier machine. Thereafter, the web since the resin ana bentonite content of the white is subjected to the action of a pressure roll or water remains substantially constant. Such a rolls in order to compact it to some extent and to solution is normally relatively unstable and there smooth the surface and, after the treatment with _ is a tendency for the resin upon standing to sepa the bentonite and resin as described, the inter rate irom the solution. The use of bentonite in feited web is dried and heated to convert the such a solution, however, makes it possible to resin to the insoluble, infusible state. In the obtain resin solutions stable over 2 period of preferred embodiment of the invention, the inter months and, in fact, the stability of such a solu- ielted web is formed b7 the process described in ticn increases upon aging. The stability im Patent Ko. 1,865,069, except when granulated or parted to such a solution by the bentonite, there nebulized wool is employed, the riffie box may be fore, makes it possible to recover and reuse the omitted. As stated, the use of pressure rolls is white water. recommended since they serve to establish the As stated previously, one object of the invention thickness of the product at a predetermined 55 is to provide a resinous composition comprising point. For example, in the preparation of a a soluble thermosetting resin in solution in an one inch board, the suction may be applied so that the stock will build up an interielted web of aqueous medium and bentan'te suspended there approximately one and one-eighth inches and by in, winen ccmpcmtioa is useable in the produc passing under the pressure rolls the thickness tion of insulating material. In making such a may be reduced to one inch. 50 composition, it is desirable to first suspend the When the stock solution delivered to the screen bentonite in water to swell it and than to incor contains the resin and bentonite, as well as the porate it with the resin solution. The concen inorganic fibrous material, the solution may foam trations of bentonite and resin in the solution may and, if this condition is encountered, a suitable correspond to those of the solution to be used in foam-reducing agent may be added. 60 the production of the insulating material such, The interfelt web is subsequently heated to dry for example, as these given above, but it is advan the web and convert the resin to the infusible, tage ms to make a core concentrated solution, insoluble state and the product may be cut to the for example, a solution containing from 20% to desired size, for example, by means of circular 50% of resin and from 10% to 40% at bentonite discs revolving a t high speed, either before or TO and then to dilate this solution at the time of after the drying and heat treatment. The in its use.. The presence oi the bentonite w ah'iiw terielted material may be heated by any suitable the resin as hereinbefore described. means and the temperature of the heat-treat Considerable modification is possible in. the ment will depend upon tire particular resin pres proportions of the constituents of the tncnigr<T.c ent. in the interielted structure. Advantageously, 75 material or the invention, as jvfii ns in th n .g ^ 9 of producing the same, without departing from the yamtial features of the invention. an intimate mixture o1f 0inorganic fibres selec^ted from the group consisting of glass wool, mineral wool and asbestos fibres and mixtures thereof, between about 2% and about 18% of bentonite, L A j T insulating material, c h a ra c te ted ter 5 between about 1% and about 10% of a synthetic high flexural strength, heat and d e c W . to- thermosetting condensation product selected Euteting values, fireproofness and ^ p r ^ n e c s , from the group consisting of phenol-formalde comprising in the form of an toterfelted web, an hyde, resorcinol-formaldehyde, urea-formalde jntiJMtemixture of inorganic fibres gected hyde and furfural-formaldehyde condensation the group consisting of glass wool, 10 products in the infusible, insoiuble state, and S d ssbwtos fibres and mixtures therec.. be zinc ammonium phosphate, said bentonite, sa.d tween about 2 % and about 18% of bentonUi and synthetic thermosetting condensation product between about 1% and about 10% of a synthetic and said zinc ammonium phosphate being m ol- thermosetting condensation product *tocted ularly interspersed with each other, at .east the from the group consisting of pbenol-iom_Jd_- IS major portion of said inorganic fibres being o - . reoremol-icxmaldetyde urea-fonna.de- ented in a plane substantially tode and furfural-formaldehyde condemation. plane of the lnterfelted weo, and said bentonite proiucts in the infusible, insoluble state, sard being present in an amount in excess of said syn bentonite and said synthetic thetic thermosetting condensation product. densation product being molecularly in^rsrxnsed 20 8 The product of claim 7 wherein the syn with each other, at least a ma<or p ^ o n e tj& ia thetic thermosetting condensation product is a inorganic fibres being oriented in a Pla^ e ^ s^ , " phenol-formaldehyde resin; and wherein the in tinny parallel to the plane of t h e web. organic fibres are granulated mineral wool fibres. and said bentonite being present in an amount m 9 The product of claim 1 wherein the toor* Scess of said synthetic thermosettmg conden- 25 garlic fibres are a mixture of asbestos fibres and Sa^ >T he^oduct of claim 1 wherein the syn mineral wool fibres. jo. The product of claim 1 wherein the inor thetic thermosetting condensation product is a ganic fibres are a mixture of asbestos fibres and phenol-formaldehyde resin. glass wool fibres. 3. i h e product of claim. 1 wherein the 30 l l . The product of claim 1 wherein the inor gsnic fibres are mineral wool Sbres. _ ganic fibres are a mixture of glass wool fibres 4. The product of maim 1 wherein p ie- syn ynrf mineral wool fibres. thetic thermosetting condensation product is a phenol-formaldehyde resin, and ^beram the in FREDERICK H. HOIiENBERG, J e. S Ja n ic fibres are granulated mineral w o o ltb r^ 35 5 An insulating material characterised by REFERENCES CITED high flexural strength, heat and to- The following references are of record in the SS Sd ulating values, fireproofness and file of this patent: ' comprising in the form of am toterfelted w e t e ^ intimate mixture of inorganic nbres 40 UNITED STATES PATENTS from the group consisting of glass wool, mm ^ 1 Number Name Mbestos fibres end mixtures thereof, between about 2% and about 18% of b ^to m te 300346 1,160,352 Carey -- _________ 24>1884 B&eheland ___ Nov. 16, 1915 between about 1% and about 10% of a syndetic 1,887,726 Weber -- ___ Nov. IE, 1932 thermosetting condensation 45 1,949,087 Squiers -----------------F-eh. 27,- 1934 from the group consisting of phenol-formalde- 1369.156 S cb u ttier------------------ Aug. 7, 1934 hvde resorcinol-formaldehyde, urea-formalde 2.011315 Seigle____________ Aug. 20, 193o hyde* and furfural-formaldehyde condensation 2,040,343 Victor et aL ------------May 12, 1936 products in the infusible, insoluble ' 2,101,449 P a r r y ________ Dec. 7, 1937 soluble alteall metal polyphosphate, said benton 50 2,122,514 ite and said synthetic thermosetting condensa 2,184,316 C rocher--- .----- July 5, 1928 P lum m er----------------Dsm 26,1939 tion product being molecuiarly interspers^i wTtii 2,155372 E hlers___ _____ _-- Mar. 26, 1940 each other, at least a major portion of id to 2321,420 Clarvoe et aL -------- Nov. 12,1940 organic fibres being oriented in a 2351336 S h ip p ______ _____ Aug. 5, 1941 tS ly parallel to the plane of the lnterfelted web. 55 2366,638 and saM bentonite being present in an amount 2398,295 H a u se r___ ______ -->ec. H y a tt_________ _-- Oct. 13, 1942 in excess of said synthetic thermosetting con 2319,033 Bernstein et aL ,, May 11, 1943 densation product. ,, __ 6. The product of claim 5 wherein jh e syn 2330306 Bernstein et aL 2335,113 . Bcxgin-----:-- _ Sept. 21,1943 ... Nov. 23,1943 thetic thermosetting condensation product is a 60 2,342 541 C a s s e l---------- _ Feb. 29, 1944 __Apr. 4, 1944 -phenol-formaldehyde resin; wherein the inor ganic fibres are mineral wool fibres, 2345366 2367,181 'Fiedler Bernstein et aL _Jan. 16,1945 the soluble polyphosphate is sodium tetraphos 2376395 Hood ,, May 22, 1945 2376,687 Goldstein et aL , __May 22, 1945 An insulating material, characterized by 65 2,376,688 high flexural strength, neat and electrical in 2385384 Goldstein et aL _ May 22, 1945 Schroy---------- __ Sept. 25,1945 sulating values, fireproofness a n d w atep rco fn e^ 2300,635 C o a rtrig tt----- _ Max. 14,1950 comprising, in the form of an lnterfelted web, 11 12 Patent No. 2,633,433 Cer,fiCaie of S e c t i o n * M a"c i M ' 1953 ^ and that t h e ^ r , speci?cation - a . ^ inter^ t e d ; column 8 V * same nja3- c o n f o ? l 7 fs P a ^ t should be r n ' ^ 6,} fo1 " ledand - aied ! | . *^<a? - -t * . [ seal] TOMAS f . j fD B P nr Sm,an' f Patents. Patented March 31, 1953 CertlScate * Correction s S Hmn <, hSne 51E, fo r ? p a . * f f i S a 8mce>ssa^ m is*take [seal] Thom as p in m p jrr Assistant Com ` ' m usionerof Patente. .......